Perturbed autophagy and DNA repair converge to promote neurodegeneration in amyotrophic lateral sclerosis and dementia Brain (IF 10.292) Pub Date : 2018-03-23 Callum Walker, Sherif F El-Khamisy
Maintaining genomic stability constitutes a major challenge facing cells. DNA breaks can arise from direct oxidative damage to the DNA backbone, the inappropriate activities of endogenous enzymes such as DNA topoisomerases, or due to transcriptionally-derived RNA/DNA hybrids (R-loops). The progressive accumulation of DNA breaks has been linked to several neurological disorders. Recently, however, several independent studies have implicated nuclear and mitochondrial genomic instability, perturbed co-transcriptional processing, and impaired cellular clearance pathways as causal and intertwined mechanisms underpinning neurodegeneration. Here, we discuss this emerging paradigm in the context of amyotrophic lateral sclerosis and frontotemporal dementia, and outline how this knowledge paves the way to novel therapeutic interventions.
Data-driven models of dominantly-inherited Alzheimer’s disease progression Brain (IF 10.292) Pub Date : 2018-03-22 Neil P Oxtoby, Alexandra L Young, David M Cash, Tammie L S Benzinger, Anne M Fagan, John C Morris, Randall J Bateman, Nick C Fox, Jonathan M Schott, Daniel C Alexander
Dominantly-inherited Alzheimer’s disease is widely hoped to hold the key to developing interventions for sporadic late onset Alzheimer’s disease. We use emerging techniques in generative data-driven disease progression modelling to characterize dominantly-inherited Alzheimer’s disease progression with unprecedented resolution, and without relying upon familial estimates of years until symptom onset. We retrospectively analysed biomarker data from the sixth data freeze of the Dominantly Inherited Alzheimer Network observational study, including measures of amyloid proteins and neurofibrillary tangles in the brain, regional brain volumes and cortical thicknesses, brain glucose hypometabolism, and cognitive performance from the Mini-Mental State Examination (all adjusted for age, years of education, sex, and head size, as appropriate). Data included 338 participants with known mutation status (211 mutation carriers in three subtypes: 163 PSEN1, 17 PSEN2, and 31 APP) and a baseline visit (age 19–66; up to four visits each, 1.1 ± 1.9 years in duration; spanning 30 years before, to 21 years after, parental age of symptom onset). We used an event-based model to estimate sequences of biomarker changes from baseline data across disease subtypes (mutation groups), and a differential equation model to estimate biomarker trajectories from longitudinal data (up to 66 mutation carriers, all subtypes combined). The two models concur that biomarker abnormality proceeds as follows: amyloid deposition in cortical then subcortical regions (∼24 ± 11 years before onset); phosphorylated tau (17 ± 8 years), tau and amyloid-β changes in cerebrospinal fluid; neurodegeneration first in the putamen and nucleus accumbens (up to 6 ± 2 years); then cognitive decline (7 ± 6 years), cerebral hypometabolism (4 ± 4 years), and further regional neurodegeneration. Our models predicted symptom onset more accurately than predictions that used familial estimates: root mean squared error of 1.35 years versus 5.54 years. The models reveal hidden detail on dominantly-inherited Alzheimer’s disease progression, as well as providing data-driven systems for fine-grained patient staging and prediction of symptom onset with great potential utility in clinical trials.
Mutant LRRK2 mediates peripheral and central immune responses leading to neurodegeneration in vivo Brain (IF 10.292) Pub Date : 2018-03-21 Elena Kozina, Shankar Sadasivan, Yun Jiao, Yuchen Dou, Zhijun Ma, Haiyan Tan, Kiran Kodali, Timothy Shaw, Junmin Peng, Richard J Smeyne
Missense mutations in the leucine rich repeat kinase 2 (LRRK2) gene result in late-onset Parkinson’s disease. The incomplete penetrance of LRRK2 mutations in humans and LRRK2 murine models of Parkinson’s disease suggests that the disease may result from a complex interplay of genetic predispositions and persistent exogenous insults. Since neuroinflammation is commonly associated with the pathogenesis of Parkinson’s disease, we examine a potential role of mutant LRRK2 in regulation of the immune response and inflammatory signalling in vivo. Here, we show that mice overexpressing human pathogenic LRRK2 mutations, but not wild-type mice or mice overexpressing human wild-type LRRK2 exhibit long-term lipopolysaccharide-induced nigral neuronal loss. This neurodegeneration is accompanied by an exacerbated neuroinflammation in the brain. The increased immune response in the brain of mutant mice subsequently has an effect on neurons by inducing intraneuronal LRRK2 upregulation. However, the enhanced neuroinflammation is unlikely to be triggered by dysfunctional microglia or infiltrated T cells and/or monocytes, but by peripheral circulating inflammatory molecules. Analysis of cytokine kinetics and inflammatory pathways in the peripheral immune cells demonstrates that LRRK2 mutation alters type II interferon immune response, suggesting that this increased neuroinflammatory response may arise outside the central nervous system. Overall, this study suggests that peripheral immune signalling plays an unexpected—but important—role in the regulation of neurodegeneration in LRRK2-associated Parkinson’s disease, and provides new targets for interfering with the onset and progression of the disease.
Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson’s disease Brain (IF 10.292) Pub Date : 2018-03-21 Jonathan Schulz, Gennaro Pagano, Juan Alberto Fernández Bonfante, Heather Wilson, Marios Politis
Currently, no reliable predictors of cognitive impairment in Parkinson’s disease exist. We hypothesized that microstructural changes at grey matter T1-weighted MRI and diffusion tensor imaging in the cholinergic system nuclei and associated limbic pathways underlie cognitive impairment in Parkinson’s disease. We performed a cross-sectional comparison between patients with Parkinson’s disease with and without cognitive impairment. We also performed a longitudinal 36-month follow-up study of cognitively intact Parkinson’s disease patients, comparing patients who remained cognitively intact to those who developed cognitive impairment. Patients with Parkinson’s disease with cognitive impairment showed lower grey matter volume and increased mean diffusivity in the nucleus basalis of Meynert, compared to patients with Parkinson’s disease without cognitive impairment. These results were confirmed both with region of interest and voxel-based analyses, and after partial volume correction. Lower grey matter volume and increased mean diffusivity in the nucleus basalis of Meynert was predictive for developing cognitive impairment in cognitively intact patients with Parkinson’s disease, independent of other clinical and non-clinical markers of the disease. Structural and microstructural alterations in entorhinal cortex, amygdala, hippocampus, insula, and thalamus were not predictive for developing cognitive impairment in Parkinson’s disease. Our findings provide evidence that degeneration of the nucleus basalis of Meynert precedes and predicts the onset of cognitive impairment, and might be used in a clinical setting as a reliable biomarker to stratify patients at higher risk of cognitive decline.
Characterization of EEG signals revealing covert cognition in the injured brain Brain (IF 10.292) Pub Date : 2018-03-19 William H Curley, Peter B Forgacs, Henning U Voss, Mary M Conte, Nicholas D Schiff
Patients with severe brain injury are difficult to assess and frequently subject to misdiagnosis. ‘Cognitive motor dissociation’ is a term used to describe a subset of such patients with preserved cognition as detected with neuroimaging methods but not evident in behavioural assessments. Unlike the locked-in state, cognitive motor dissociation after severe brain injury is prominently marked by concomitant injuries across the cerebrum in addition to limited or no motoric function. In the present study, we sought to characterize the EEG signals used as indicators of cognition in patients with disorders of consciousness and examine their reliability for potential future use to re-establish communication. We compared EEG-based assessments to the results of using similar methods with functional MRI. Using power spectral density analysis to detect EEG evidence of task performance (Two Group Test, P ≤ 0.05, with false discovery rate correction), we found evidence of the capacity to follow commands in 21 of 28 patients with severe brain injury and all 15 healthy individuals studied. We found substantial variability in the temporal and spatial characteristics of significant EEG signals among the patients in contrast to only modest variation in these domains across healthy controls; the majority of healthy controls showed suppression of either 8–12 Hz ‘alpha’ or 13–40 Hz ‘beta’ power during task performance, or both. Nine of the 21 patients with EEG evidence of command-following also demonstrated functional MRI evidence of command-following. Nine of the patients with command-following capacity demonstrated by EEG showed no behavioural evidence of a communication channel as detected by a standardized behavioural assessment, the Coma Recovery Scale – Revised. We further examined the potential contributions of fluctuations in arousal that appeared to co-vary with some patients’ ability to reliably generate EEG signals in response to command. Five of nine patients with statistically indeterminate responses to one task tested showed a positive response after accounting for variations in overall background state (as visualized in the qualitative shape of the power spectrum) and grouping of trial runs with similar background state characteristics. Our findings reveal signal variations of EEG responses in patients with severe brain injuries and provide insight into the underlying physiology of cognitive motor dissociation. These results can help guide future efforts aimed at re-establishment of communication in such patients who will need customization for brain–computer interfaces.
TDP-43 regulates the alternative splicing of hnRNP A1 to yield an aggregation-prone variant in amyotrophic lateral sclerosis Brain (IF 10.292) Pub Date : 2018-03-19 Jade-Emmanuelle Deshaies, Lulzim Shkreta, Alexander J Moszczynski, Hadjara Sidibé, Sabrina Semmler, Aurélien Fouillen, Estelle R Bennett, Uriya Bekenstein, Laurie Destroismaisons, Johanne Toutant, Quentin Delmotte, Kathryn Volkening, Stéphanie Stabile, Anaïs Aulas, Yousra Khalfallah, Hermona Soreq, Antonio Nanci, Michael J Strong, Benoit Chabot, Christine Vande Velde
The RNA binding proteins TDP-43 (encoded by TARDBP) and hnRNP A1 (HNRNPA1) are each mutated in certain amyotrophic lateral sclerosis cases and are often mislocalized in cytoplasmic aggregates within motor neurons of affected patients. Cytoplasmic inclusions of TDP-43, which are accompanied by a depletion of nuclear TDP-43, are observed in most amyotrophic lateral sclerosis cases and nearly half of frontotemporal dementia cases. Here, we report that TDP-43 binds HNRNPA1 pre-mRNA and modulates its splicing, and that depletion of nuclear TDP-43 results in increased inclusion of a cassette exon in the HNRNPA1 transcript, and consequently elevated protein levels of an isoform containing an elongated prion-like domain, referred to as hnRNP A1B. Combined in vivo and in vitro approaches demonstrated greater fibrillization propensity for hnRNP A1B, which drives protein aggregation and is toxic to cells. Moreover, amyotrophic lateral sclerosis patients with documented TDP-43 pathology showed neuronal hnRNP A1B cytoplasmic accumulation, indicating that TDP-43 mislocalization may contribute to neuronal vulnerability and loss via altered HNRNPA1 pre-mRNA splicing and function. Given that TDP-43 and hnRNP A1 each bind, and thus modulate, a third of the transcriptome, our data suggest a much broader disruption in RNA metabolism than previously considered.
Corrigendum Brain (IF 10.292) Pub Date : 2018-03-15
Patricia Rodriguez-Rodriguez, Anna Sandebring-Matton, Paula Merino-Serrais, Cristina Parrado-Fernandez, Alberto Rabano, Bengt Winblad, Jesús Ávila, Isidre Ferrer, Angel Cedazo-Minguez. Tau hyperphosphorylation induces oligomeric insulin accumulation and insulin resistance in neurons. Brain 2017; 140: 3269–3285; 10.1093/brain/awx256.
Disrupted dynamic network reconfiguration of the language system in temporal lobe epilepsy Brain (IF 10.292) Pub Date : 2018-03-15 Xiaosong He, Danielle S Bassett, Ganne Chaitanya, Michael R Sperling, Lauren Kozlowski, Joseph I Tracy
Temporal lobe epilepsy tends to reshape the language system causing maladaptive reorganization that can be characterized by task-based functional MRI, and eventually can contribute to surgical decision making processes. However, the dynamic interacting nature of the brain as a complex system is often neglected, with many studies treating the language system as a static monolithic structure. Here, we demonstrate that as a specialized and integrated system, the language network is inherently dynamic, characterized by rich patterns of regional interactions, whose transient dynamics are disrupted in patients with temporal lobe epilepsy. Specifically, we applied tools from dynamic network neuroscience to functional MRI data collected from 50 temporal lobe epilepsy patients and 30 matched healthy controls during performance of a verbal fluency task, as well as during rest. By assigning 16 language-related regions into four subsystems (i.e. bilateral frontal and temporal), we observed regional specialization in both the probability of transient interactions and the frequency of such changes, in both healthy controls and patients during task performance but not rest. Furthermore, we found that both left and right temporal lobe epilepsy patients displayed reduced interactions within the left frontal ‘core’ subsystem compared to the healthy controls, while left temporal lobe epilepsy patients were unique in showing enhanced interactions between the left frontal ‘core’ and the right temporal subsystems. Also, both patient groups displayed reduced flexibility in the transient interactions of the left temporal and right frontal subsystems, which formed the ‘periphery’ of the language network. Importantly, such group differences were again evident only during task condition. Lastly, through random forest regression, we showed that dynamic reconfiguration of the language system tracks individual differences in verbal fluency with superior prediction accuracy compared to traditional activation-based static measures. Our results suggest dynamic network measures may be an effective biomarker for detecting the language dysfunction associated with neurological diseases such as temporal lobe epilepsy, specifying both the type of neuronal communications that are missing in these patients and those that are potentially added but maladaptive. Further advancements along these lines, transforming how we characterize and map language networks in the brain, have a high probability of altering clinical decision making in neurosurgical centres.
PRRT2 controls neuronal excitability by negatively modulating Na+ channel 1.2/1.6 activity Brain (IF 10.292) Pub Date : 2018-03-15 Floriana Fruscione, Pierluigi Valente, Bruno Sterlini, Alessandra Romei, Simona Baldassari, Manuela Fadda, Cosimo Prestigio, Giorgia Giansante, Jacopo Sartorelli, Pia Rossi, Alicia Rubio, Antonio Gambardella, Thierry Nieus, Vania Broccoli, Anna Fassio, Pietro Baldelli, Anna Corradi, Federico Zara, Fabio Benfenati
Proline-rich transmembrane protein 2 (PRRT2) is the causative gene for a heterogeneous group of familial paroxysmal neurological disorders that include seizures with onset in the first year of life (benign familial infantile seizures), paroxysmal kinesigenic dyskinesia or a combination of both. Most of the PRRT2 mutations are loss-of-function leading to haploinsufficiency and 80% of the patients carry the same frameshift mutation (c.649dupC; p.Arg217Profs*8), which leads to a premature stop codon. To model the disease and dissect the physiological role of PRRT2, we studied the phenotype of neurons differentiated from induced pluripotent stem cells from previously described heterozygous and homozygous siblings carrying the c.649dupC mutation. Single-cell patch-clamp experiments on induced pluripotent stem cell-derived neurons from homozygous patients showed increased Na+ currents that were fully rescued by expression of wild-type PRRT2. Closely similar electrophysiological features were observed in primary neurons obtained from the recently characterized PRRT2 knockout mouse. This phenotype was associated with an increased length of the axon initial segment and with markedly augmented spontaneous and evoked firing and bursting activities evaluated, at the network level, by multi-electrode array electrophysiology. Using HEK-293 cells stably expressing Nav channel subtypes, we demonstrated that the expression of PRRT2 decreases the membrane exposure and Na+ current of Nav1.2/Nav1.6, but not Nav1.1, channels. Moreover, PRRT2 directly interacted with Nav1.2/Nav1.6 channels and induced a negative shift in the voltage-dependence of inactivation and a slow-down in the recovery from inactivation. In addition, by co-immunoprecipitation assays, we showed that the PRRT2-Nav interaction also occurs in brain tissue. The study demonstrates that the lack of PRRT2 leads to a hyperactivity of voltage-dependent Na+ channels in homozygous PRRT2 knockout human and mouse neurons and that, in addition to the reported synaptic functions, PRRT2 is an important negative modulator of Nav1.2 and Nav1.6 channels. Given the predominant paroxysmal character of PRRT2-linked diseases, the disturbance in cellular excitability by lack of negative modulation of Na+ channels appears as the key pathogenetic mechanism.
Reply: Noisy but not placebo: defining metrics for effects of neurofeedback Brain (IF 10.292) Pub Date : 2018-03-13 Manuel Schabus
Noisy but not placebo: defining metrics for effects of neurofeedback Brain (IF 10.292) Pub Date : 2018-03-13 Matthias Witte, Silvia Erika Kober, Guilherme Wood
A neurocomputational account of reward and novelty processing and effects of psychostimulants in attention deficit hyperactivity disorder Brain (IF 10.292) Pub Date : 2018-03-13 Arjun Sethi, Valerie Voon, Hugo D Critchley, Mara Cercignani, Neil A Harrison
Computational models of reinforcement learning have helped dissect discrete components of reward-related function and characterize neurocognitive deficits in psychiatric illnesses. Stimulus novelty biases decision-making, even when unrelated to choice outcome, acting as if possessing intrinsic reward value to guide decisions toward uncertain options. Heightened novelty seeking is characteristic of attention deficit hyperactivity disorder, yet how this influences reward-related decision-making is computationally encoded, or is altered by stimulant medication, is currently uncertain. Here we used an established reinforcement-learning task to model effects of novelty on reward-related behaviour during functional MRI in 30 adults with attention deficit hyperactivity disorder and 30 age-, sex- and IQ-matched control subjects. Each participant was tested on two separate occasions, once ON and once OFF stimulant medication. OFF medication, patients with attention deficit hyperactivity disorder showed significantly impaired task performance (P = 0.027), and greater selection of novel options (P = 0.004). Moreover, persistence in selecting novel options predicted impaired task performance (P = 0.025). These behavioural deficits were accompanied by a significantly lower learning rate (P = 0.011) and heightened novelty signalling within the substantia nigra/ventral tegmental area (family-wise error corrected P < 0.05). Compared to effects in controls, stimulant medication improved attention deficit hyperactivity disorder participants’ overall task performance (P = 0.011), increased reward-learning rates (P = 0.046) and enhanced their ability to differentiate optimal from non-optimal novel choices (P = 0.032). It also reduced substantia nigra/ventral tegmental area responses to novelty. Preliminary cross-sectional evidence additionally suggested an association between long-term stimulant treatment and a reduction in the rewarding value of novelty. These data suggest that aberrant substantia nigra/ventral tegmental area novelty processing plays an important role in the suboptimal reward-related decision-making characteristic of attention deficit hyperactivity disorder. Compared to effects in controls, abnormalities in novelty processing and reward-related learning were improved by stimulant medication, suggesting that they may be disorder-specific targets for the pharmacological management of attention deficit hyperactivity disorder symptoms.
CaMKII-dependent endoplasmic reticulum fission by whisker stimulation and during cortical spreading depolarization Brain (IF 10.292) Pub Date : 2018-03-12 Krzysztof Kucharz, Martin Lauritzen
Cortical spreading depolarization waves, the cause underlying migraine aura, are also the markers and mechanism of pathology in the acutely injured human brain. Propagation of spreading depolarization wave uniquely depends on the interaction between presynaptic and postsynaptic glutamate N-methyl-d-aspartate receptors (NMDARs). In the normally perfused brain, even a single wave causes a massive depolarization of neurons and glia, which results in transient loss of neuronal function and depression of the ongoing electrocorticographic activity. Endoplasmic reticulum is the cellular organelle of particular importance for modulation of neurotransmission. Neuronal endoplasmic reticulum structure is assumed to be persistently continuous in neurons, but is rapidly lost within 1 to 2 min of global cerebral ischaemia, i.e. the organelle disintegrates by fission. This phenomenon appears to be timed with the cardiac arrest-induced cortical spreading depolarizations, rather than ensuing cell death. To what extent NMDAR-dependent processes may trigger neuronal endoplasmic reticulum fission and whether fission is reversible in the normally perfused brain is unknown. We used two-photon microscopy to examine neuronal endoplasmic reticulum structural dynamics during whisker stimulation and cortical spreading depolarizations in vivo. Somatosensory stimulation triggered loss of endoplasmic reticulum continuity, a likely outcome of constriction and fission, in dendritic spines within less than 10 s of stimulation, which was spontaneously reversible and recovery to normal took 5 min. The endoplasmic reticulum fission was inhibited by blockade of NMDAR and Ca2+/calmodulin-dependent protein kinase II (CaMKII) activated downstream of the NMDARs, whereas inhibition of guanosine triphosphate hydrolases hindered regain of endoplasmic reticulum continuity, i.e. fusion. In contrast to somatosensory stimulation, endoplasmic reticulum fission during spreading depolarization was widespread and present in dendrites and spines, and was preceded by dramatic rise in intracellular Ca2+. The endoplasmic reticulum fission during spreading depolarization was more persistent, as 1 h after the depolarization cortical neurons still exhibited loss of endoplasmic reticulum continuity. Notably, endoplasmic reticulum fission was accompanied with loss of electrocorticographic activity, whereas subsequent regain of synaptic function paralleled the organelle fusion. Furthermore, blocking CaMKII activity partly rescued endoplasmic reticulum fission and markedly shortened the recovery time of brain spontaneous activity. Thus, prevention of endoplasmic reticulum fission with CaMKII inhibitors may be a novel strategy to rescue brain function in patients with migraine and a promising therapeutic avenue in the acutely injured brain.
Optical coherence tomography in autosomal recessive spastic ataxia of Charlevoix-Saguenay Brain (IF 10.292) Pub Date : 2018-03-12 Michael H Parkinson, Ana P Bartmann, Lisa M S Clayton, Suran Nethisinghe, Rolph Pfundt, J Paul Chapple, Mary M Reilly, Hadi Manji, Nicholas J Wood, Fion Bremner, Paola Giunti
Autosomal recessive spastic ataxia of Charlevoix-Saguenay is a rare neurodegenerative disorder caused by mutations in the SACS gene. Thickened retinal nerve fibres visible on fundoscopy have previously been described in these patients; however, thickening of the retinal nerve fibre layer as demonstrated by optical coherence tomography appears to be a more sensitive and specific feature. To test this observation, we assessed 292 individuals (191 patients with ataxia and 101 control subjects) by peripapillary time-domain optical coherence tomography. The patients included 146 with a genetic diagnosis of ataxia (17 autosomal spastic ataxia of Charlevoix-Saguenay, 59 Friedreich’s ataxia, 53 spinocerebellar ataxias, 17 other genetically confirmed ataxias) and 45 with cerebellar ataxia of unknown cause. The controls included 13 asymptomatic heterozygotes for SACS mutations and 88 unaffected controls. The cases with autosomal recessive spastic ataxia of Charlevoix-Saguenay included 11 previously unpublished SACS mutations, of which seven were nonsense and four missense mutations. Most patients were visually asymptomatic and had no previous history of ophthalmic complaints and normal or near normal visual test results. None had visual symptoms directly attributable to the retinal changes. Twelve of the 17 cases (70.6%) had thickened retinal nerve fibres visible on fundoscopy. All patients with autosomal recessive spastic ataxia of Charlevoix-Saguenay had thickening of the peripapillary retinal nerve fibre layer on optical coherence tomography, whereas all the remaining cases and controls except one showed normal or reduced average peripapillary retinal nerve fibre layer thickness on optical coherence tomography. We propose a cut-off value of 119 µm in average peripapillary retinal nerve fibre layer thickness, which provides a sensitivity of 100% and specificity of 99.4% amongst patients affected with ataxia. This is the largest cohort of patients with this condition to undergo systematic evaluation by optical coherence tomography. This is a useful tool in identifying cases of autosomal recessive spastic ataxia of Charlevoix-Saguenay from other causes of ataxia. Visualization of thickened retinal fibres by direct fundoscopy is less sensitive. We therefore advocate the use of this technique in the assessment of possible cases of this condition.
KEAP1 inhibition is neuroprotective and suppresses the development of epilepsy Brain (IF 10.292) Pub Date : 2018-03-12 Tawfeeq Shekh-Ahmad, Ramona Eckel, Sharadha Dayalan Naidu, Maureen Higgins, Masayuki Yamamoto, Albena T Dinkova-Kostova, Stjepana Kovac, Andrey Y Abramov, Matthew C Walker
Hippocampal sclerosis is a common acquired disease that is a major cause of drug-resistant epilepsy. A mechanism that has been proposed to lead from brain insult to hippocampal sclerosis is the excessive generation of reactive oxygen species, and consequent mitochondrial failure. Here we use a novel strategy to increase endogenous antioxidant defences using RTA 408, which we show activates nuclear factor erythroid 2-related factor 2 (Nrf2, encoded by NFE2L2) through inhibition of kelch like ECH associated protein 1 (KEAP1) through its primary sensor C151. Activation of Nrf2 with RTA 408 inhibited reactive oxygen species production, mitochondrial depolarization and cell death in an in vitro model of seizure-like activity. RTA 408 given after status epilepticus in vivo increased ATP, prevented neuronal death, and dramatically reduced (by 94%) the frequency of late spontaneous seizures for at least 4 months following status epilepticus. Thus, acute KEAP1 inhibition following status epilepticus exerts a neuroprotective and disease-modifying effect, supporting the hypothesis that reactive oxygen species generation is a key event in the development of epilepsy.
Longitudinal tau PET in ageing and Alzheimer’s disease Brain (IF 10.292) Pub Date : 2018-03-12 Clifford R Jack, Heather J Wiste, Christopher G Schwarz, Val J Lowe, Matthew L Senjem, Prashanthi Vemuri, Stephen D Weigand, Terry M Therneau, Dave S Knopman, Jeffrey L Gunter, David T Jones, Jonathan Graff-Radford, Kejal Kantarci, Rosebud O Roberts, Michelle M Mielke, Mary M Machulda, Ronald C Petersen
Our objective was to compare different whole-brain and region-specific measurements of within-person change on serial tau PET and evaluate its utility for clinical trials. We studied 126 individuals: 59 cognitively unimpaired with normal amyloid, 37 cognitively unimpaired with abnormal amyloid, and 30 cognitively impaired with an amnestic phenotype and abnormal amyloid. All had baseline amyloid PET and two tau PET, MRI, and clinical assessments. We compared the topography across all cortical regions of interest of tau PET accumulation rates and the rates of four different whole-brain or region-specific meta-regions of interest among the three clinical groups. We computed sample size estimates for change in tau PET, cortical volume, and memory/mental status indices for use as outcome measures in clinical trials. The cognitively unimpaired normal amyloid group had no observable tau accumulation throughout the brain. Tau accumulation rates in cognitively unimpaired abnormal amyloid were low [0.006 standardized uptake value ratio (SUVR), 0.5%, per year] but greater than rates in the cognitively unimpaired normal amyloid group in the basal and mid-temporal, retrosplenial, posterior cingulate, and entorhinal regions of interest. Thus, the earliest elevation in accumulation rates was widespread and not confined to the entorhinal cortex. Tau accumulation rates in the cognitively impaired abnormal amyloid group were 0.053 SUVR (3%) per year and greater than rates in cognitively unimpaired abnormal amyloid in all cortical areas except medial temporal. Rates of accumulation in the four meta-regions of interest differed but only slightly from one another. Among all tau PET meta-regions of interest, sample size estimates were smallest for a temporal lobe composite within cognitively unimpaired abnormal amyloid and for the late Alzheimer’s disease meta-region of interest within cognitively impaired abnormal amyloid. The ordering of the sample size estimates by outcome measure was MRI < tau PET < cognitive measures. At a group-wise level, observable rates of short-term serial tau accumulation were only seen in the presence of abnormal amyloid. As disease progressed to clinically symptomatic stages (cognitively impaired abnormal amyloid), observable rates of tau accumulation were seen uniformly throughout the brain providing evidence that tau does not accumulate in one area at a time or in start-stop, stepwise sequence. The information captured by rate measures in different meta-regions of interest, even those with little topographic overlap, was similar. The implication is that rate measurements from simple meta-regions of interest, without the need for Braak-like staging, may be sufficient to capture progressive within-person accumulation of pathologic tau. Tau PET SUVR measures should be an efficient outcome measure in disease-modifying clinical trials.
FDG-PET in tau-negative amnestic dementia resembles that of autopsy-proven hippocampal sclerosis Brain (IF 10.292) Pub Date : 2018-03-12 Hugo Botha, William G Mantyh, Melissa E Murray, David S Knopman, Scott A Przybelski, Heather J Wiste, Jonathan Graff-Radford, Keith A Josephs, Christopher G Schwarz, Walter K Kremers, Bradley F Boeve, Ronald C Petersen, Mary M Machulda, Joseph E Parisi, Dennis W Dickson, Val Lowe, Clifford R Jack, David T Jones
Predicting underlying pathology based on clinical presentation has historically proven difficult, especially in older cohorts. Age-related hippocampal sclerosis may account for a significant proportion of elderly participants with amnestic dementia. Advances in molecular neuroimaging have allowed for detailed biomarker-based phenotyping, but in the absence of antemortem markers of hippocampal sclerosis, cases of mixed pathology remain problematic. We evaluated the utility of 18F-FDG-PET to differentiate flortaucipir tau PET negative from flortaucipir positive amnestic mild cognitive impairment and dementia and used an autopsy confirmed cohort to test the hypothesis that hippocampal sclerosis might account for the observed pattern. We identified impaired participants (Clinical Dementia Rating > 0) with amnestic presentations ≥ 75 years who had MRI and PET imaging with 18F-FDG (glucose metabolism), Pittsburgh compound B (amyloid) and flortaucipir (tau) performed within a year of cognitive assessment. These were stratified into amyloid positive/negative and tau positive/negative according to the A/T/N classification scheme. Our sample included 15 amyloid and tau-positive participants, and nine tau-negative participants (five of whom were amyloid-positive). For the autopsy cohort, sequential cases with antemortem 18F-FDG-PET were screened and those with TDP-43-negative Alzheimer’s disease (10 cases) and TDP-43-positive hippocampal sclerosis (eight cases) were included. We compared each group to controls and to each other in a voxel-based analysis, and supplemented this with a region of interest-based analysis comparing medial to inferior temporal metabolism. Tau-positive and negative cases did not differ on neuropsychological testing or structural magnetic resonance biomarkers. Tau-negative cases had focal medial temporal and posterior cingulate/retrosplenial hypometabolism regardless of amyloid status, whereas tau-positive cases had additional lateral parietal and inferior temporal involvement. The inferior/medial temporal metabolism ratio was significantly different between the groups with the tau-negative group having a higher ratio. In the autopsy series, hippocampal sclerosis cases had greater medial temporal hypometabolism than Alzheimer’s disease cases, who had more parietal and lateral/inferior temporal hypometabolism. Again, the ratio between temporal regions of interest differed significantly between groups. Two of the tau-negative patients, both of whom had an elevated inferior/medial temporal ratio, came to autopsy during the study and were found to have hippocampal sclerosis. Our finding that tau-negative amnestic mild cognitive impairment and dementia is associated with focal medial temporal and posterior cingulate hypometabolism extends prior reports in amyloid-negative cases. The inferior/medial temporal metabolism ratio can help identify tau-negative cases of amnestic dementia and may serve as a biomarker for hippocampal sclerosis.
Protein instability, haploinsufficiency, and cortical hyper-excitability underlie STXBP1 encephalopathy Brain (IF 10.292) Pub Date : 2018-03-12 Jovana Kovačević, Gregoire Maroteaux, Desiree Schut, Maarten Loos, Mohit Dubey, Julika Pitsch, Esther Remmelink, Bastijn Koopmans, James Crowley, L Niels Cornelisse, Patrick F Sullivan, Susanne Schoch, Ruud F Toonen, Oliver Stiedl, Matthijs Verhage
De novo heterozygous mutations in STXBP1/Munc18-1 cause early infantile epileptic encephalopathies (EIEE4, OMIM #612164) characterized by infantile epilepsy, developmental delay, intellectual disability, and can include autistic features. We characterized the cellular deficits for an allelic series of seven STXBP1 mutations and developed four mouse models that recapitulate the abnormal EEG activity and cognitive aspects of human STXBP1-encephalopathy. Disease-causing STXBP1 variants supported synaptic transmission to a variable extent on a null background, but had no effect when overexpressed on a heterozygous background. All disease variants had severely decreased protein levels. Together, these cellular studies suggest that impaired protein stability and STXBP1 haploinsufficiency explain STXBP1-encephalopathy and that, therefore, Stxbp1+/− mice provide a valid mouse model. Simultaneous video and EEG recordings revealed that Stxbp1+/− mice with different genomic backgrounds recapitulate the seizure/spasm phenotype observed in humans, characterized by myoclonic jerks and spike-wave discharges that were suppressed by the antiepileptic drug levetiracetam. Mice heterozygous for Stxbp1 in GABAergic neurons only, showed impaired viability, 50% died within 2–3 weeks, and the rest showed stronger epileptic activity. c-Fos staining implicated neocortical areas, but not other brain regions, as the seizure foci. Stxbp1+/− mice showed impaired cognitive performance, hyperactivity and anxiety-like behaviour, without altered social behaviour. Taken together, these data demonstrate the construct, face and predictive validity of Stxbp1+/− mice and point to protein instability, haploinsufficiency and imbalanced excitation in neocortex, as the underlying mechanism of STXBP1-encephalopathy. The mouse models reported here are valid models for development of therapeutic interventions targeting STXBP1-encephalopathy.
The striatal kinase DCLK3 produces neuroprotection against mutant huntingtin Brain (IF 10.292) Pub Date : 2018-03-09 Laurie Galvan, Laetitia Francelle, Marie-Claude Gaillard, Lucie de Longprez, Maria-Angeles Carrillo-de Sauvage, Géraldine Liot, Karine Cambon, Lev Stimmer, Sophie Luccantoni, Julien Flament, Julien Valette, Michel de Chaldée, Gwenaelle Auregan, Martine Guillermier, Charlène Joséphine, Fanny Petit, Caroline Jan, Margot Jarrige, Noëlle Dufour, Gilles Bonvento, Sandrine Humbert, Frédéric Saudou, Philippe Hantraye, Karine Merienne, Alexis-Pierre Bemelmans, Anselme L. Perrier, Nicole Déglon, Emmanuel Brouillet
The neurobiological functions of a number of kinases expressed in the brain are unknown. Here, we report new findings on DCLK3 (doublecortin like kinase 3), which is preferentially expressed in neurons in the striatum and dentate gyrus. Its function has never been investigated. DCLK3 expression is markedly reduced in Huntington’s disease. Recent data obtained in studies related to cancer suggest DCLK3 could have an anti-apoptotic effect. Thus, we hypothesized that early loss of DCLK3 in Huntington’s disease may render striatal neurons more susceptible to mutant huntingtin (mHtt). We discovered that DCLK3 silencing in the striatum of mice exacerbated the toxicity of an N-terminal fragment of mHtt. Conversely, overexpression of DCLK3 reduced neurodegeneration produced by mHtt. DCLK3 also produced beneficial effects on motor symptoms in a knock-in mouse model of Huntington’s disease. Using different mutants of DCLK3, we found that the kinase activity of the protein plays a key role in neuroprotection. To investigate the potential mechanisms underlying DCLK3 effects, we studied the transcriptional changes produced by the kinase domain in human striatal neurons in culture. Results show that DCLK3 regulates in a kinase-dependent manner the expression of many genes involved in transcription regulation and nucleosome/chromatin remodelling. Consistent with this, histological evaluation showed DCLK3 is present in the nucleus of striatal neurons and, protein-protein interaction experiments suggested that the kinase domain interacts with zinc finger proteins, including the transcriptional activator adaptor TADA3, a core component of the Spt-ada-Gcn5 acetyltransferase (SAGA) complex which links histone acetylation to the transcription machinery. Our novel findings suggest that the presence of DCLK3 in striatal neurons may play a key role in transcription regulation and chromatin remodelling in these brain cells, and show that reduced expression of the kinase in Huntington’s disease could render the striatum highly vulnerable to neurodegeneration.
Artificial limb representation in amputees Brain (IF 10.292) Pub Date : 2018-03-09 Fiona M Z van den Heiligenberg, Tanya Orlov, Scott N Macdonald, Eugene P Duff, David Henderson Slater, Christian F Beckmann, Heidi Johansen-Berg, Jody C Culham, Tamar R Makin
The human brain contains multiple hand-selective areas, in both the sensorimotor and visual systems. Could our brain repurpose neural resources, originally developed for supporting hand function, to represent and control artificial limbs? We studied individuals with congenital or acquired hand-loss (hereafter one-handers) using functional MRI. We show that the more one-handers use an artificial limb (prosthesis) in their everyday life, the stronger visual hand-selective areas in the lateral occipitotemporal cortex respond to prosthesis images. This was found even when one-handers were presented with images of active prostheses that share the functionality of the hand but not necessarily its visual features (e.g. a ‘hook’ prosthesis). Further, we show that daily prosthesis usage determines large-scale inter-network communication across hand-selective areas. This was demonstrated by increased resting state functional connectivity between visual and sensorimotor hand-selective areas, proportional to the intensiveness of everyday prosthesis usage. Further analysis revealed a 3-fold coupling between prosthesis activity, visuomotor connectivity and usage, suggesting a possible role for the motor system in shaping use-dependent representation in visual hand-selective areas, and/or vice versa. Moreover, able-bodied control participants who routinely observe prosthesis usage (albeit less intensively than the prosthesis users) showed significantly weaker associations between degree of prosthesis observation and visual cortex activity or connectivity. Together, our findings suggest that altered daily motor behaviour facilitates prosthesis-related visual processing and shapes communication across hand-selective areas. This neurophysiological substrate for prosthesis embodiment may inspire rehabilitation approaches to improve usage of existing substitutionary devices and aid implementation of future assistive and augmentative technologies.
Corrigendum Brain (IF 10.292) Pub Date : 2018-03-08
Ortal Barel, May Christine V. Malicdan, Bruria Ben-Zeev, Judith Kandel, Hadass Pri-Chen, Joshi Stephen, Inês G. Castro, Jeremy Metz, Osama Atawa, Sharon Moshkovitz, Esther Ganelin, Iris Barshack, Sylvie Polak-Charcon, Dvora Nass, Dina Marek-Yagel, Ninette Amariglio, Nechama Shalva, Thierry Vilboux, Carlos Ferreira, Ben Pode-Shakked, Gali Heimer, Chen Hoffmann, Tal Yardeni, Andreea Nissenkorn, Camila Avivi, Eran Eyal, Nitzan Kol, Efrat Glick Saar, Douglas C. Wallace, William A. Gahl, Gideon Rechavi, Michael Schrader, David M. Eckmann, Yair Anikster. Deleterious variants in TRAK1 disrupt mitochondrial movement and cause fatal encephalopathy. Brain 2017; 140: 568–81; 10.1093/brain/awx002.
Preferential degradation of cognitive networks differentiates Alzheimer’s disease from ageing Brain (IF 10.292) Pub Date : 2018-03-07 Jasmeer P Chhatwal, Aaron P Schultz, Keith A Johnson, Trey Hedden, Sehily Jaimes, Tammie L S Benzinger, Clifford Jack, Beau M Ances, John M Ringman, Daniel S Marcus, Bernardino Ghetti, Martin R Farlow, Adrian Danek, Johannes Levin, Igor Yakushev, Christoph Laske, Robert A Koeppe, Douglas R Galasko, Chengjie Xiong, Colin L Masters, Peter R Schofield, Kirsi M Kinnunen, Stephen Salloway, Ralph N Martins, Eric McDade, Nigel J Cairns, Virginia D Buckles, John C Morris, Randall Bateman, Reisa A Sperling
Converging evidence from structural, metabolic and functional connectivity MRI suggests that neurodegenerative diseases, such as Alzheimer’s disease, target specific neural networks. However, age-related network changes commonly co-occur with neuropathological cascades, limiting efforts to disentangle disease-specific alterations in network function from those associated with normal ageing. Here we elucidate the differential effects of ageing and Alzheimer’s disease pathology through simultaneous analyses of two functional connectivity MRI datasets: (i) young participants harbouring highly-penetrant mutations leading to autosomal-dominant Alzheimer’s disease from the Dominantly Inherited Alzheimer’s Network (DIAN), an Alzheimer’s disease cohort in which age-related comorbidities are minimal and likelihood of progression along an Alzheimer’s disease trajectory is extremely high; and (ii) young and elderly participants from the Harvard Aging Brain Study, a cohort in which imaging biomarkers of amyloid burden and neurodegeneration can be used to disambiguate ageing alone from preclinical Alzheimer’s disease. Consonant with prior reports, we observed the preferential degradation of cognitive (especially the default and dorsal attention networks) over motor and sensory networks in early autosomal-dominant Alzheimer’s disease, and found that this distinctive degradation pattern was magnified in more advanced stages of disease. Importantly, a nascent form of the pattern observed across the autosomal-dominant Alzheimer’s disease spectrum was also detectable in clinically normal elderly with clear biomarker evidence of Alzheimer’s disease pathology (preclinical Alzheimer’s disease). At the more granular level of individual connections between node pairs, we observed that connections within cognitive networks were preferentially targeted in Alzheimer’s disease (with between network connections relatively spared), and that connections between positively coupled nodes (correlations) were preferentially degraded as compared to connections between negatively coupled nodes (anti-correlations). In contrast, ageing in the absence of Alzheimer’s disease biomarkers was characterized by a far less network-specific degradation across cognitive and sensory networks, of between- and within-network connections, and of connections between positively and negatively coupled nodes. We go on to demonstrate that formalizing the differential patterns of network degradation in ageing and Alzheimer’s disease may have the practical benefit of yielding connectivity measurements that highlight early Alzheimer’s disease-related connectivity changes over those due to age-related processes. Together, the contrasting patterns of connectivity in Alzheimer’s disease and ageing add to prior work arguing against Alzheimer’s disease as a form of accelerated ageing, and suggest multi-network composite functional connectivity MRI metrics may be useful in the detection of early Alzheimer’s disease-specific alterations co-occurring with age-related connectivity changes. More broadly, our findings are consistent with a specific pattern of network degradation associated with the spreading of Alzheimer’s disease pathology within targeted neural networks.
RSRC1 mutation affects intellect and behaviour through aberrant splicing and transcription, downregulating IGFBP3 Brain (IF 10.292) Pub Date : 2018-03-07 Yonatan Perez, Shay Menascu, Idan Cohen, Rotem Kadir, Omer Basha, Zamir Shorer, Hila Romi, Gal Meiri, Tatiana Rabinski, Rivka Ofir, Esti Yeger-Lotem, Ohad S Birk
RSRC1, whose polymorphism is associated with altered brain function in schizophrenia, is a member of the serine and arginine rich-related protein family. Through homozygosity mapping and whole exome sequencing we show that RSRC1 mutation causes an autosomal recessive syndrome of intellectual disability, aberrant behaviour, hypotonia and mild facial dysmorphism with normal brain MRI. Further, we show that RSRC1 is ubiquitously expressed, and that the RSRC1 mutation triggers nonsense-mediated mRNA decay of the RSRC1 transcript in patients’ fibroblasts. Short hairpin RNA (shRNA)-mediated lentiviral silencing and overexpression of RSRC1 in SH-SY5Y cells demonstrated that RSRC1 has a role in alternative splicing and transcription regulation. Transcriptome profiling of RSRC1-silenced cells unravelled specific differentially expressed genes previously associated with intellectual disability, hypotonia and schizophrenia, relevant to the disease phenotype. Protein-protein interaction network modelling suggested possible intermediate interactions by which RSRC1 affects gene-specific differential expression. Patient-derived induced pluripotent stem cells, differentiated into neural progenitor cells, showed expression dynamics similar to the RSRC1-silenced SH-SY5Y model. Notably, patient neural progenitor cells had 9.6-fold downregulated expression of IGFBP3, whose brain expression is affected by MECP2, aberrant in Rett syndrome. Interestingly, Igfbp3-null mice have behavioural impairment, abnormal synaptic function and monoaminergic neurotransmission, likely correlating with the disease phenotype.
Electromagnetic signatures of the preclinical and prodromal stages of Alzheimer’s disease Brain (IF 10.292) Pub Date : 2018-03-07 Akinori Nakamura, Pablo Cuesta, Alberto Fernández, Yutaka Arahata, Kaori Iwata, Izumi Kuratsubo, Masahiko Bundo, Hideyuki Hattori, Takashi Sakurai, Koji Fukuda, Yukihiko Washimi, Hidetoshi Endo, Akinori Takeda, Kersten Diers, Ricardo Bajo, Fernando Maestú, Kengo Ito, Takashi Kato
Biomarkers useful for the predementia stages of Alzheimer’s disease are needed. Electroencephalography and magnetoencephalography (MEG) are expected to provide potential biomarker candidates for evaluating the predementia stages of Alzheimer’s disease. However, the physiological relevance of EEG/MEG signal changes and their role in pathophysiological processes such as amyloid-β deposition and neurodegeneration need to be elucidated. We evaluated 28 individuals with mild cognitive impairment and 38 cognitively normal individuals, all of whom were further classified into amyloid-β-positive mild cognitive impairment (n = 17, mean age 74.7 ± 5.4 years, nine males), amyloid-β-negative mild cognitive impairment (n = 11, mean age 73.8 ± 8.8 years, eight males), amyloid-β-positive cognitively normal (n = 13, mean age 71.8 ± 4.4 years, seven males), and amyloid-β-negative cognitively normal (n = 25, mean age 72.5 ± 3.4 years, 11 males) individuals using Pittsburgh compound B-PET. We measured resting state MEG for 5 min with the eyes closed, and investigated regional spectral patterns of MEG signals using atlas-based region of interest analysis. Then, the relevance of the regional spectral patterns and their associations with pathophysiological backgrounds were analysed by integrating information from Pittsburgh compound B-PET, fluorodeoxyglucose-PET, structural MRI, and cognitive tests. The results demonstrated that regional spectral patterns of resting state activity could be separated into several types of MEG signatures as follows: (i) the effects of amyloid-β deposition were expressed as the alpha band power augmentation in medial frontal areas; (ii) the delta band power increase in the same region was associated with disease progression within the Alzheimer’s disease continuum and was correlated with entorhinal atrophy and an Alzheimer’s disease-like regional decrease in glucose metabolism; and (iii) the global theta power augmentation, which was previously considered to be an Alzheimer’s disease-related EEG/MEG signature, was associated with general cognitive decline and hippocampal atrophy, but was not specific to Alzheimer’s disease because these changes could be observed in the absence of amyloid-β deposition. The results suggest that these MEG signatures may be useful as unique biomarkers for the predementia stages of Alzheimer’s disease.
Reply: Towards personalized therapy for multiple sclerosis: limitations of observational data Brain (IF 10.292) Pub Date : 2018-03-03 Tomas Kalincik
Towards personalized therapy for multiple sclerosis: limitations of observational data Brain (IF 10.292) Pub Date : 2018-03-03 Ewout W Steyerberg, Brian Claggett
Editorial Brain (IF 10.292) Pub Date : 2018-02-27 Dimitri M Kullmann
In this issue of Brain David Brenner and colleagues report a hot-spot of mutations in the kinesin family gene KIF5A causing familial amyotrophic lateral sclerosis, adding to the existing genetic evidence implicating altered cytoskeletal function and intracellular transport in this disease. Two other papers broaden the range of manifestations of genetic disorders involving glutamate receptors. Juliette Piard, George Umanah, Frederike Harms and co-workers identify a mutation in the AAA+ family ATPase Thorase, encoded by ATAD1, which leads to lethal encephalopathy and arthrogryposis, while Andrew Fry, Katherine Fawcett and colleagues report an association between de novo mutations of GRIN1, which codes for the GluN1 subunit of NMDA receptors, and extensive bilateral polymicrogyria, with several probands presenting with developmental delay, microcephaly, visual impairment or refractory epilepsy....
Polymicrogyria and GRIN1 mutations: altered connections, altered excitability Brain (IF 10.292) Pub Date : 2018-02-27 Peter B Crino
This scientific commentary refers to ‘De novo mutations in GRIN1 cause extensive bilateral polymicrogyria’, by Fry et al. (doi:10.1093/brain/awx358).
Cognitive ageing and Alzheimer’s disease: the cholinergic system redux Brain (IF 10.292) Pub Date : 2018-02-27 David L Sultzer
This scientific commentary refers to ‘Effect of cholinergic treatment depends on cholinergic integrity in early Alzheimer’s disease’, by Richter et al. (doi:10.1093/brain/awx356).
Why not try harder? Computational approach to motivation deficits in neuro-psychiatric diseases Brain (IF 10.292) Pub Date : 2017-11-29 Mathias Pessiglione, Fabien Vinckier, Sébastien Bouret, Jean Daunizeau, Raphaël Le Bouc
Motivation deficits, such as apathy, are pervasive in both neurological and psychiatric diseases. Even when they are not the core symptom, they reduce quality of life, compromise functional outcome and increase the burden for caregivers. They are currently assessed with clinical scales that do not give any mechanistic insight susceptible to guide therapeutic intervention. Here, we present another approach that consists of phenotyping the behaviour of patients in motivation tests, using computational models. These formal models impose a precise and operational definition of motivation that is embedded in decision theory. Motivation can be defined as the function that orients and activates the behaviour according to two attributes: a content (the goal) and a quantity (the goal value). Decision theory offers a way to quantify motivation, as the cost that patients would accept to endure in order to get the benefit of achieving their goal. We then review basic and clinical studies that have investigated the trade-off between the expected cost entailed by potential actions and the expected benefit associated with potential rewards. These studies have shown that the trade-off between effort and reward involves specific cortical, subcortical and neuromodulatory systems, such that it may be shifted in particular clinical conditions, and reinstated by appropriate treatments. Finally, we emphasize the promises of computational phenotyping for clinical purposes. Ideally, there would be a one-to-one mapping between specific neural components and distinct computational variables and processes of the decision model. Thus, fitting computational models to patients’ behaviour would allow inferring of the dysfunctional mechanism in both cognitive terms (e.g. hyposensitivity to reward) and neural terms (e.g. lack of dopamine). This computational approach may therefore not only give insight into the motivation deficit but also help personalize treatment.
A homozygous ATAD1 mutation impairs postsynaptic AMPA receptor trafficking and causes a lethal encephalopathy Brain (IF 10.292) Pub Date : 2018-01-30 Juliette Piard, George K Essien Umanah, Frederike L Harms, Leire Abalde-Atristain, Daniel Amram, Melissa Chang, Rong Chen, Malik Alawi, Vincenzo Salpietro, Mark I Rees, Seo-Kyung Chung, Henry Houlden, Alain Verloes, Ted M Dawson, Valina L Dawson, Lionel Van Maldergem, Kerstin Kutsche
Members of the AAA+ superfamily of ATPases are involved in the unfolding of proteins and disassembly of protein complexes and aggregates. ATAD1 encoding the ATPase family, AAA+ domain containing 1-protein Thorase plays an important role in the function and integrity of mitochondria and peroxisomes. Postsynaptically, Thorase controls the internalization of excitatory, glutamatergic AMPA receptors by disassembling complexes between the AMPA receptor-binding protein, GRIP1, and the AMPA receptor subunit GluA2. Using whole-exome sequencing, we identified a homozygous frameshift mutation in the last exon of ATAD1 [c.1070_1071delAT; p.(His357Argfs*15)] in three siblings who presented with a severe, lethal encephalopathy associated with stiffness and arthrogryposis. Biochemical and cellular analyses show that the C-terminal end of Thorase mutant gained a novel function that strongly impacts its oligomeric state, reduces stability or expression of a set of Golgi, peroxisomal and mitochondrial proteins and affects disassembly of GluA2 and Thorase oligomer complexes. Atad1−/− neurons expressing Thorase mutantHis357Argfs*15 display reduced amount of GluA2 at the cell surface suggesting that the Thorase mutant may inhibit the recycling back and/or reinsertion of AMPA receptors to the plasma membrane. Taken together, our molecular and functional analyses identify an activating ATAD1 mutation as a new cause of severe encephalopathy and congenital stiffness.
SCO2 mutations cause early-onset axonal Charcot-Marie-Tooth disease associated with cellular copper deficiency Brain (IF 10.292) Pub Date : 2018-01-16 Adriana P Rebelo, Dimah Saade, Claudia V Pereira, Amjad Farooq, Tyler C Huff, Lisa Abreu, Carlos T Moraes, Diana Mnatsakanova, Kathy Mathews, Hua Yang, Eric A Schon, Stephan Zuchner, Michael E Shy
Recessive mutations in the mitochondrial copper-binding protein SCO2, cytochrome c oxidase (COX) assembly protein, have been reported in several cases with fatal infantile cardioencephalomyopathy with COX deficiency. Significantly expanding the known phenotypic spectrum, we identified compound heterozygous variants in SCO2 in two unrelated patients with axonal polyneuropathy, also known as Charcot-Marie-Tooth disease type 4. Different from previously described cases, our patients developed predominantly motor neuropathy, they survived infancy, and they have not yet developed the cardiomyopathy that causes death in early infancy in reported patients. Both of our patients harbour missense mutations near the conserved copper-binding motif (CXXXC), including the common pathogenic variant E140K and a novel change D135G. In addition, each patient carries a second mutation located at the same loop region, resulting in compound heterozygote changes E140K/P169T and D135G/R171Q. Patient fibroblasts showed reduced levels of SCO2, decreased copper levels and COX deficiency. Given that another Charcot-Marie-Tooth disease gene, ATP7A, is a known copper transporter, our findings further underline the relevance of copper metabolism in Charcot-Marie-Tooth disease.
HDAC6 is a therapeutic target in mutant GARS-induced Charcot-Marie-Tooth disease Brain (IF 10.292) Pub Date : 2018-02-05 Veronick Benoy, Lawrence Van Helleputte, Robert Prior, Constantin d’Ydewalle, Wanda Haeck, Natasja Geens, Wendy Scheveneels, Begga Schevenels, M Zameel Cader, Kevin Talbot, Alan P Kozikowski, Pieter Vanden Berghe, Philip Van Damme, Wim Robberecht, Ludo Van Den Bosch
Peripheral nerve axons require a well-organized axonal microtubule network for efficient transport to ensure the constant crosstalk between soma and synapse. Mutations in more than 80 different genes cause Charcot-Marie-Tooth disease, which is the most common inherited disorder affecting peripheral nerves. This genetic heterogeneity has hampered the development of therapeutics for Charcot-Marie-Tooth disease. The aim of this study was to explore whether histone deacetylase 6 (HDAC6) can serve as a therapeutic target focusing on the mutant glycyl-tRNA synthetase (GlyRS/GARS)-induced peripheral neuropathy. Peripheral nerves and dorsal root ganglia from the C201R mutant Gars mouse model showed reduced acetylated α-tubulin levels. In primary dorsal root ganglion neurons, mutant GlyRS affected neurite length and disrupted normal mitochondrial transport. We demonstrated that GlyRS co-immunoprecipitated with HDAC6 and that this interaction was blocked by tubastatin A, a selective inhibitor of the deacetylating function of HDAC6. Moreover, HDAC6 inhibition restored mitochondrial axonal transport in mutant GlyRS-expressing neurons. Systemic delivery of a specific HDAC6 inhibitor increased α-tubulin acetylation in peripheral nerves and partially restored nerve conduction and motor behaviour in mutant Gars mice. Our study demonstrates that α-tubulin deacetylation and disrupted axonal transport may represent a common pathogenic mechanism underlying Charcot-Marie-Tooth disease and it broadens the therapeutic potential of selective HDAC6 inhibition to other genetic forms of axonal Charcot-Marie-Tooth disease.
Hot-spot KIF5A mutations cause familial ALS Brain (IF 10.292) Pub Date : 2018-01-12 David Brenner, Rüstem Yilmaz, Kathrin Müller, Torsten Grehl, Susanne Petri, Thomas Meyer, Julian Grosskreutz, Patrick Weydt, Wolfgang Ruf, Christoph Neuwirth, Markus Weber, Susana Pinto, Kristl G Claeys, Berthold Schrank, Berit Jordan, Antje Knehr, Kornelia Günther, Annemarie Hübers, Daniel Zeller, Christian Kubisch, Sibylle Jablonka, Michael Sendtner, Thomas Klopstock, Mamede de Carvalho, Anne Sperfeld, Guntram Borck, Alexander E Volk, Johannes Dorst, Joachim Weis, Markus Otto, Joachim Schuster, Kelly Del Tredici, Heiko Braak, Karin M Danzer, Axel Freischmidt, Thomas Meitinger, Tim M Strom, Albert C Ludolph, Peter M Andersen, Jochen H Weishaupt, Ute Weyen, Andreas Hermann, Tim Hagenacker, Jan Christoph Koch, Paul Lingor, Bettina Göricke, Stephan Zierz, Petra Baum, Joachim Wolf, Andrea Winkler, Peter Young, Ulrich Bogdahn, Johannes Prudlo, Jan Kassubek.
Heterozygous missense mutations in the N-terminal motor or coiled-coil domains of the kinesin family member 5A (KIF5A) gene cause monogenic spastic paraplegia (HSP10) and Charcot-Marie-Tooth disease type 2 (CMT2). Moreover, heterozygous de novo frame-shift mutations in the C-terminal domain of KIF5A are associated with neonatal intractable myoclonus, a neurodevelopmental syndrome. These findings, together with the observation that many of the disease genes associated with amyotrophic lateral sclerosis disrupt cytoskeletal function and intracellular transport, led us to hypothesize that mutations in KIF5A are also a cause of amyotrophic lateral sclerosis. Using whole exome sequencing followed by rare variant analysis of 426 patients with familial amyotrophic lateral sclerosis and 6137 control subjects, we detected an enrichment of KIF5A splice-site mutations in amyotrophic lateral sclerosis (2/426 compared to 0/6137 in controls; P = 4.2 × 10−3), both located in a hot-spot in the C-terminus of the protein and predicted to affect splicing exon 27. We additionally show co-segregation with amyotrophic lateral sclerosis of two canonical splice-site mutations in two families. Investigation of lymphoblast cell lines from patients with KIF5A splice-site mutations revealed the loss of mutant RNA expression and suggested haploinsufficiency as the most probable underlying molecular mechanism. Furthermore, mRNA sequencing of a rare non-synonymous missense mutation (predicting p.Arg1007Gly) located in the C-terminus of the protein shortly upstream of the splice donor of exon 27 revealed defective KIF5A pre-mRNA splicing in respective patient-derived cell lines owing to abrogation of the donor site. Finally, the non-synonymous single nucleotide variant rs113247976 (minor allele frequency = 1.00% in controls, n = 6137), also located in the C-terminal region [p.(Pro986Leu) in exon 26], was significantly enriched in familial amyotrophic lateral sclerosis patients (minor allele frequency = 3.40%; P = 1.28 × 10−7). Our study demonstrates that mutations located specifically in a C-terminal hotspot of KIF5A can cause a classical amyotrophic lateral sclerosis phenotype, and underline the involvement of intracellular transport processes in amyotrophic lateral sclerosis pathogenesis.
De novo mutations in GRIN1 cause extensive bilateral polymicrogyria Brain (IF 10.292) Pub Date : 2018-01-22 Andrew E Fry, Katherine A Fawcett, Nathanel Zelnik, Hongjie Yuan, Belinda A N Thompson, Lilach Shemer-Meiri, Thomas D Cushion, Hood Mugalaasi, David Sims, Neil Stoodley, Seo-Kyung Chung, Mark I Rees, Chirag V Patel, Louise A Brueton, Valérie Layet, Fabienne Giuliano, Michael P Kerr, Ehud Banne, Vardiella Meiner, Tally Lerman-Sagie, Katherine L Helbig, Laura H Kofman, Kristin M Knight, Wenjuan Chen, Varun Kannan, Chun Hu, Hirofumi Kusumoto, Jin Zhang, Sharon A Swanger, Gil H Shaulsky, Ghayda M Mirzaa, Alison M Muir, Heather C Mefford, William B Dobyns, Amanda B Mackenzie, Jonathan G L Mullins, Johannes R Lemke, Nadia Bahi-Buisson, Stephen F Traynelis, Heledd F Iago, Daniela T Pilz
See Crino (doi:10.1093/brain/awy047) for a scientific commentary on this article.
Stereotyped high-frequency oscillations discriminate seizure onset zones and critical functional cortex in focal epilepsy Brain (IF 10.292) Pub Date : 2018-01-30 Su Liu, Candan Gurses, Zhiyi Sha, Michael M Quach, Altay Sencer, Nerses Bebek, Daniel J Curry, Sujit Prabhu, Sudhakar Tummala, Thomas R Henry, Nuri F Ince
High-frequency oscillations in local field potentials recorded with intracranial EEG are putative biomarkers of seizure onset zones in epileptic brain. However, localized 80–500 Hz oscillations can also be recorded from normal and non-epileptic cerebral structures. When defined only by rate or frequency, physiological high-frequency oscillations are indistinguishable from pathological ones, which limit their application in epilepsy presurgical planning. We hypothesized that pathological high-frequency oscillations occur in a repetitive fashion with a similar waveform morphology that specifically indicates seizure onset zones. We investigated the waveform patterns of automatically detected high-frequency oscillations in 13 epilepsy patients and five control subjects, with an average of 73 subdural and intracerebral electrodes recorded per patient. The repetitive oscillatory waveforms were identified by using a pipeline of unsupervised machine learning techniques and were then correlated with independently clinician-defined seizure onset zones. Consistently in all patients, the stereotypical high-frequency oscillations with the highest degree of waveform similarity were localized within the seizure onset zones only, whereas the channels generating high-frequency oscillations embedded in random waveforms were found in the functional regions independent from the epileptogenic locations. The repetitive waveform pattern was more evident in fast ripples compared to ripples, suggesting a potential association between waveform repetition and the underlying pathological network. Our findings provided a new tool for the interpretation of pathological high-frequency oscillations that can be efficiently applied to distinguish seizure onset zones from functionally important sites, which is a critical step towards the translation of these signature events into valid clinical biomarkers.
Spike-related haemodynamic responses overlap with high frequency oscillations in patients with focal epilepsy Brain (IF 10.292) Pub Date : 2018-01-18 Karina A González Otárula, Hui Ming Khoo, Nicolás von Ellenrieder, Jeffery A Hall, François Dubeau, Jean Gotman
Simultaneous scalp EEG/functional MRI measures non-invasively haemodynamic responses to interictal epileptic discharges, which are related to the epileptogenic zone. High frequency oscillations are also an excellent indicator of this zone, but are primarily recorded from intracerebral EEG. We studied the spatial overlap of these two important markers in patients with drug-resistant epilepsy to assess if their combination could help better define the extent of the epileptogenic zone. We included patients who underwent EEG-functional MRI and later intracerebral EEG. Based on intracerebral EEG findings, we separated patients with unifocal seizures from patients with multifocal or unknown onset seizures. Haemodynamic t-maps were coregistered with the intracerebral electrode positions. Each EEG channel was classified as pertaining to one of the following categories: primary haemodynamic cluster (maximum t-value), secondary cluster (t-value > 90% of the primary cluster) or outside the primary and secondary clusters. We marked high frequency oscillations (ripples: 80–250 Hz; fast ripples: 250–500 Hz) during 1 h of slow wave sleep, and compared their rates in each haemodynamic category. After classifying channels as high- or low-rate, the proportion of high-rate channels within the primary or primary plus secondary clusters was compared to the proportion expected by chance. Twenty-five patients, 11 with unifocal and 14 with multifocal/unknown seizure onsets, were studied. We found a significantly higher median high frequency oscillation rate in the primary cluster compared to secondary cluster and outside these two clusters for the unifocal group (P < 0.0001), but not for the multifocal/unknown group. For the unifocal group, the number of high-rate channels within the primary or primary plus secondary clusters was significantly higher than expected by chance. This held only for the high-ripple-rate channels in the multifocal/unknown group. At the patient level, most patients (18/25, or 72%) had at least one high-rate channel within a primary cluster. In patients with unifocal epilepsy, the maximum haemodynamic response (primary cluster) related to scalp interictal discharges overlaps with the tissue generating high frequency oscillations at high rates. If intracranial EEG is warranted, this response should be explored. As a tentative clinical use of the combination of these techniques we propose that higher high frequency oscillation rates inside than outside the maximum response indicates that the patient has indeed a focal epileptogenic zone demarcated by this response, whereas similar rates inside and outside may indicate a widespread epileptogenic zone or an epileptogenic zone not covered by the implantation.
A novel metabolism-based phenotypic drug discovery platform in zebrafish uncovers HDACs 1 and 3 as a potential combined anti-seizure drug target Brain (IF 10.292) Pub Date : 2018-01-24 Kingsley Ibhazehiebo, Cezar Gavrilovici, Cristiane L de la Hoz, Shun-Chieh Ma, Renata Rehak, Gaurav Kaushik, Paola L Meza Santoscoy, Lucas Scott, Nandan Nath, Do-Young Kim, Jong M Rho, Deborah M Kurrasch
Despite the development of newer anti-seizure medications over the past 50 years, 30–40% of patients with epilepsy remain refractory to treatment. One explanation for this lack of progress is that the current screening process is largely biased towards transmembrane channels and receptors, and ignores intracellular proteins and enzymes that might serve as efficacious molecular targets. Here, we report the development of a novel drug screening platform that harnesses the power of zebrafish genetics and combines it with in vivo bioenergetics screening assays to uncover therapeutic agents that improve mitochondrial health in diseased animals. By screening commercially available chemical libraries of approved drugs, for which the molecular targets and pathways are well characterized, we were able to reverse-identify the proteins targeted by efficacious compounds and confirm the physiological roles that they play by utilizing other pharmacological ligands. Indeed, using an 870-compound screen in kcna1-morpholino epileptic zebrafish larvae, we uncovered vorinostat (Zolinza™; suberanilohydroxamic acid, SAHA) as a potent anti-seizure agent. We further demonstrated that vorinostat decreased average daily seizures by ∼60% in epileptic Kcna1-null mice using video-EEG recordings. Given that vorinostat is a broad histone deacetylase (HDAC) inhibitor, we then delineated a specific subset of HDACs, namely HDACs 1 and 3, as potential drug targets for future screening. In summary, we have developed a novel phenotypic, metabolism-based experimental therapeutics platform that can be used to identify new molecular targets for future drug discovery in epilepsy.
Characteristics and mechanism of apogeotropic central positional nystagmus Brain (IF 10.292) Pub Date : 2018-01-24 Jeong-Yoon Choi, Stefan Glasauer, Ji Hyun Kim, David S Zee, Ji-Soo Kim
Here we characterize persistent apogeotropic type of central positional nystagmus, and compare it with the apogeotropic nystagmus of benign paroxysmal positional vertigo involving the lateral canal. Nystagmus was recorded in 27 patients with apogeotropic type of central positional nystagmus (22 with unilateral and five with diffuse cerebellar lesions) and 20 patients with apogeotropic nystagmus of benign paroxysmal positional vertigo. They were tested while sitting, while supine with the head straight back, and in the right and left ear-down positions. The intensity of spontaneous nystagmus was similar while sitting and supine in apogeotropic type of central positional nystagmus, but greater when supine in apogeotropic nystagmus of benign paroxysmal positional vertigo. In central positional nystagmus, when due to a focal pathology, the lesions mostly overlapped in the vestibulocerebellum (nodulus, uvula, and tonsil). We suggest a mechanism for apogeotropic type of central positional nystagmus based on the location of lesions and a model that uses the velocity-storage mechanism. During both tilt and translation, the otolith organs can relay the same gravito-inertial acceleration signal. This inherent ambiguity can be resolved by a ‘tilt-estimator circuit’ in which information from the semicircular canals about head rotation is combined with otolith information about linear acceleration through the velocity-storage mechanism. An example of how this mechanism works in normal subjects is the sustained horizontal nystagmus that is produced when a normal subject is rotated at a constant speed around an axis that is tilted away from the true vertical (off-vertical axis rotation). We propose that when the tilt-estimator circuit malfunctions, for example, with lesions in the vestibulocerebellum, the estimate of the direction of gravity is erroneously biased away from true vertical. If the bias is toward the nose, when the head is turned to the side while supine, there will be sustained, unwanted, horizontal positional nystagmus (apogeotropic type of central positional nystagmus) because of an inappropriate feedback signal indicating that the head is rotating when it is not.
Migraine with visual aura associated with thicker visual cortex Brain (IF 10.292) Pub Date : 2018-01-18 David Gaist, Anders Hougaard, Ellen Garde, Nina Linde Reislev, Rikke Wiwie, Pernille Iversen, Camilla Gøbel Madsen, Morten Blaabjerg, Helle Hvilsted Nielsen, Thomas Krøigård, Kamilla Østergaard, Kirsten Ohm Kyvik, Jacob Hjelmborg, Kristoffer Madsen, Hartwig Roman Siebner, Messoud Ashina
Until recent years it was believed that migraine with aura was a disorder causing intermittent neurological symptoms, with no impact on brain structure. However, recent MRI studies have reported increased cortical thickness of visual and somatosensory areas in patients with migraine with aura, suggesting that such structural alterations were either due to increased neuronal density in the areas involved, or a result of multiple episodes of cortical spreading depression as part of aura attacks. Subsequent studies have yielded conflicting results, possibly due to methodological reasons, e.g. small number of subjects. In this cross-sectional study, we recruited females aged 30–60 years from the nationwide Danish Twin Registry. Brain MRI of females with migraine with aura (patients), their co-twins, and unrelated migraine-free twins (controls) were performed at a single centre and assessed for cortical thickness in predefined cortical areas (V1, V2, V3A, MT, somatosensory cortex), blinded to headache diagnoses. The difference in cortical thickness between patients and controls adjusted for age, and other potential confounders was assessed. Comparisons of twin pairs discordant for migraine with aura were also performed. Comparisons were based on 166 patients, 30 co-twins, and 137 controls. Compared with controls, patients had a thicker cortex in areas V2 [adjusted mean difference 0.032 mm (95% confidence interval 0.003 to 0.061), V3A [adjusted mean difference 0.037 mm (95% confidence interval 0.008 to 0.067)], while differences in the remaining areas examined were not statistically significant [adjusted mean difference (95% confidence interval): V1 0.022 (−0.007 to 0.052); MT: 0.018 (−0.011 to 0.047); somatosensory cortex: 0.020 (−0.009 to 0.049)]. We found no association between the regions of interest and active migraine, or number of lifetime aura attacks. Migraine with aura discordant twin pairs (n = 30) only differed in mean thickness of V2 (0.039 mm, 95% CI 0.005 to 0.074). In conclusion, females with migraine with aura have a thicker cortex corresponding to visual areas and our results indicate this may be an inherent trait rather than a result of repeated aura attacks.
Multiple sclerosis risk variants alter expression of co-stimulatory genes in B cells Brain (IF 10.292) Pub Date : 2018-01-18 Ide Smets, Barnaby Fiddes, Josselyn E Garcia-Perez, Di He, Klara Mallants, Wenjia Liao, James Dooley, George Wang, Stephanie Humblet-Baron, Bénédicte Dubois, Alastair Compston, Joanne Jones, Alasdair Coles, Adrian Liston, Maria Ban, An Goris, Stephen Sawcer
The increasing evidence supporting a role for B cells in the pathogenesis of multiple sclerosis prompted us to investigate the influence of known susceptibility variants on the surface expression of co-stimulatory molecules in these cells. Using flow cytometry we measured surface expression of CD40 and CD86 in B cells from 68 patients and 162 healthy controls that were genotyped for the multiple sclerosis associated single nucleotide polymorphisms (SNPs) rs4810485, which maps within the CD40 gene, and rs9282641, which maps within the CD86 gene. We found that carrying the risk allele rs4810485*T lowered the cell-surface expression of CD40 in all tested B cell subtypes (in total B cells P ≤ 5.10 × 10−5 in patients and ≤4.09 × 10−6 in controls), while carrying the risk allele rs9282641*G increased the expression of CD86, with this effect primarily seen in the naïve B cell subset (P = 0.048 in patients and 5.38 × 10−5 in controls). In concordance with these results, analysis of RNA expression demonstrated that the risk allele rs4810485*T resulted in lower total CD40 expression (P = 0.057) but with an increased proportion of alternative splice-forms leading to decoy receptors (P = 4.00 × 10−7). Finally, we also observed that the risk allele rs4810485*T was associated with decreased levels of interleukin-10 (P = 0.020), which is considered to have an immunoregulatory function downstream of CD40. Given the importance of these co-stimulatory molecules in determining the immune reaction that appears in response to antigen our data suggest that B cells might have an important antigen presentation and immunoregulatory role in the pathogenesis of multiple sclerosis.
Dopaminergic abnormalities following traumatic brain injury Brain (IF 10.292) Pub Date : 2018-01-17 Peter O Jenkins, Sara De Simoni, Niall J Bourke, Jessica Fleminger, Gregory Scott, David J Towey, William Svensson, Sameer Khan, Maneesh Patel, Richard Greenwood, James H Cole, David J Sharp
Traumatic brain injury can reduce striatal dopamine levels. The cause of this is uncertain, but is likely to be related to damage to the nigrostriatal system. We investigated the pattern of striatal dopamine abnormalities using 123I-Ioflupane single-photon emission computed tomography (SPECT) scans and their relationship to nigrostriatal damage and clinical features. We studied 42 moderate–severe traumatic brain injury patients with cognitive impairments but no motor parkinsonism signs and 20 healthy controls. 123I-Ioflupane scanning was used to assess dopamine transporter levels. Clinical scan reports were compared to quantitative dopamine transporter results. Advanced MRI methods were used to assess the nigrostriatal system, including the area through which the nigrostriatal projections pass as defined from high-resolution Human Connectome data. Detailed clinical and neuropsychological assessments were performed. Around 20% of our moderate–severe patients had clear evidence of reduced specific binding ratios for the dopamine transporter in the striatum measured using 123I-Ioflupane SPECT. The caudate was affected more consistently than other striatal regions. Dopamine transporter abnormalities were associated with reduced substantia nigra volume. In addition, diffusion MRI provided evidence of damage to the regions through which the nigrostriatal tract passes, particularly the area traversed by dopaminergic projections to the caudate. Only a small percentage of patients had evidence of macroscopic lesions in the striatum and there was no relationship between presence of lesions and dopamine transporter specific binding ratio abnormalities. There was also no relationship between reduced volume in the striatal subregions and reduced dopamine transporter specific binding ratios. Patients with low caudate dopamine transporter specific binding ratios show impaired processing speed and executive dysfunction compared to patients with normal levels. Taken together, our results suggest that the dopaminergic system is affected by a moderate–severe traumatic brain injury in a significant proportion of patients, even in the absence of clinical motor parkinsonism. Reduced dopamine transporter levels are most commonly seen in the caudate and this is likely to reflect the pattern of nigrostriatal tract damage produced by axonal injury and associated midbrain damage.
Progression of tremor in early stages of Parkinson’s disease: a clinical and neuroimaging study Brain (IF 10.292) Pub Date : 2018-01-22 Jacopo Pasquini, Roberto Ceravolo, Zahi Qamhawi, Jee-Young Lee, Günther Deuschl, David James Brooks, Ubaldo Bonuccelli, Nicola Pavese
See Jankovic (doi:10.1093/brain/awx361) for a scientific commentary on this article.
Spatial patterns of progressive brain volume loss after moderate-severe traumatic brain injury Brain (IF 10.292) Pub Date : 2018-01-04 James H Cole, Amy Jolly, Sara de Simoni, Niall Bourke, Maneesh C Patel, Gregory Scott, David J Sharp
Traumatic brain injury leads to significant loss of brain volume, which continues into the chronic stage. This can be sensitively measured using volumetric analysis of MRI. Here we: (i) investigated longitudinal patterns of brain atrophy; (ii) tested whether atrophy is greatest in sulcal cortical regions; and (iii) showed how atrophy could be used to power intervention trials aimed at slowing neurodegeneration. In 61 patients with moderate-severe traumatic brain injury (mean age = 41.55 years ± 12.77) and 32 healthy controls (mean age = 34.22 years ± 10.29), cross-sectional and longitudinal (1-year follow-up) brain structure was assessed using voxel-based morphometry on T1-weighted scans. Longitudinal brain volume changes were characterized using a novel neuroimaging analysis pipeline that generates a Jacobian determinant metric, reflecting spatial warping between baseline and follow-up scans. Jacobian determinant values were summarized regionally and compared with clinical and neuropsychological measures. Patients with traumatic brain injury showed lower grey and white matter volume in multiple brain regions compared to controls at baseline. Atrophy over 1 year was pronounced following traumatic brain injury. Patients with traumatic brain injury lost a mean (± standard deviation) of 1.55% ± 2.19 of grey matter volume per year, 1.49% ± 2.20 of white matter volume or 1.51% ± 1.60 of whole brain volume. Healthy controls lost 0.55% ± 1.13 of grey matter volume and gained 0.26% ± 1.11 of white matter volume; equating to a 0.22% ± 0.83 reduction in whole brain volume. Atrophy was greatest in white matter, where the majority (84%) of regions were affected. This effect was independent of and substantially greater than that of ageing. Increased atrophy was also seen in cortical sulci compared to gyri. There was no relationship between atrophy and time since injury or age at baseline. Atrophy rates were related to memory performance at the end of the follow-up period, as well as to changes in memory performance, prior to multiple comparison correction. In conclusion, traumatic brain injury results in progressive loss of brain tissue volume, which continues for many years post-injury. Atrophy is most prominent in the white matter, but is also more pronounced in cortical sulci compared to gyri. These findings suggest the Jacobian determinant provides a method of quantifying brain atrophy following a traumatic brain injury and is informative in determining the long-term neurodegenerative effects after injury. Power calculations indicate that Jacobian determinant images are an efficient surrogate marker in clinical trials of neuroprotective therapeutics.
Evidence for a subcortical origin of mirror movements after stroke: a longitudinal study Brain (IF 10.292) Pub Date : 2018-01-31 Naveed Ejaz, Jing Xu, Meret Branscheidt, Benjamin Hertler, Heidi Schambra, Mario Widmer, Andreia V. Faria, Michelle D. Harran, Juan C. Cortes, Nathan Kim, Pablo A. Celnik, Tomoko Kitago, Andreas R. Luft, John W. Krakauer, Jörn Diedrichsen
Following a stroke, mirror movements are unintended movements that appear in the non-paretic hand when the paretic hand voluntarily moves. Mirror movements have previously been linked to overactivation of sensorimotor areas in the non-lesioned hemisphere. In this study, we hypothesized that mirror movements might instead have a subcortical origin, and are the by-product of subcortical motor pathways upregulating their contributions to the paretic hand. To test this idea, we first characterized the time course of mirroring in 53 first-time stroke patients, and compared it to the time course of activities in sensorimotor areas of the lesioned and non-lesioned hemispheres (measured using functional MRI). Mirroring in the non-paretic hand was exaggerated early after stroke (Week 2), but progressively diminished over the year with a time course that parallelled individuation deficits in the paretic hand. We found no evidence of cortical overactivation that could explain the time course changes in behaviour, contrary to the cortical model of mirroring. Consistent with a subcortical origin of mirroring, we predicted that subcortical contributions should broadly recruit fingers in the non-paretic hand, reflecting the limited capacity of subcortical pathways in providing individuated finger control. We therefore characterized finger recruitment patterns in the non-paretic hand during mirroring. During mirroring, non-paretic fingers were broadly recruited, with mirrored forces in homologous fingers being only slightly larger (1.76 times) than those in non-homologous fingers. Throughout recovery, the pattern of finger recruitment during mirroring for patients looked like a scaled version of the corresponding control mirroring pattern, suggesting that the system that is responsible for mirroring in controls is upregulated after stroke. Together, our results suggest that post-stroke mirror movements in the non-paretic hand, like enslaved movements in the paretic hand, are caused by the upregulation of a bilaterally organized subcortical system.
Anatomy of aphasia revisited Brain (IF 10.292) Pub Date : 2018-01-17 Julius Fridriksson, Dirk-Bart den Ouden, Argye E Hillis, Gregory Hickok, Chris Rorden, Alexandra Basilakos, Grigori Yourganov, Leonardo Bonilha
In most cases, aphasia is caused by strokes involving the left hemisphere, with more extensive damage typically being associated with more severe aphasia. The classical model of aphasia commonly adhered to in the Western world is the Wernicke-Lichtheim model. The model has been in existence for over a century, and classification of aphasic symptomatology continues to rely on it. However, far more detailed models of speech and language localization in the brain have been formulated. In this regard, the dual stream model of cortical brain organization proposed by Hickok and Poeppel is particularly influential. Their model describes two processing routes, a dorsal stream and a ventral stream, that roughly support speech production and speech comprehension, respectively, in normal subjects. Despite the strong influence of the dual stream model in current neuropsychological research, there has been relatively limited focus on explaining aphasic symptoms in the context of this model. Given that the dual stream model represents a more nuanced picture of cortical speech and language organization, cortical damage that causes aphasic impairment should map clearly onto the dual processing streams. Here, we present a follow-up study to our previous work that used lesion data to reveal the anatomical boundaries of the dorsal and ventral streams supporting speech and language processing. Specifically, by emphasizing clinical measures, we examine the effect of cortical damage and disconnection involving the dorsal and ventral streams on aphasic impairment. The results reveal that measures of motor speech impairment mostly involve damage to the dorsal stream, whereas measures of impaired speech comprehension are more strongly associated with ventral stream involvement. Equally important, many clinical tests that target behaviours such as naming, speech repetition, or grammatical processing rely on interactions between the two streams. This latter finding explains why patients with seemingly disparate lesion locations often experience similar impairments on given subtests. Namely, these individuals’ cortical damage, although dissimilar, affects a broad cortical network that plays a role in carrying out a given speech or language task. The current data suggest this is a more accurate characterization than ascribing specific lesion locations as responsible for specific language deficits.
A method for inferring regional origins of neurodegeneration Brain (IF 10.292) Pub Date : 2018-02-02 Justin Torok, Pedro D Maia, Fon Powell, Sneha Pandya, Ashish Raj
Alzheimer’s disease, the most common form of dementia, is characterized by the emergence and spread of senile plaques and neurofibrillary tangles, causing widespread neurodegeneration. Though the progression of Alzheimer’s disease is considered to be stereotyped, the significant variability within clinical populations obscures this interpretation on the individual level. Of particular clinical importance is understanding where exactly pathology, e.g. tau, emerges in each patient and how the incipient atrophy pattern relates to future spread of disease. Here we demonstrate a newly developed graph theoretical method of inferring prior disease states in patients with Alzheimer’s disease and mild cognitive impairment using an established network diffusion model and an L1-penalized optimization algorithm. Although the ‘seeds’ of origin using our inference method successfully reproduce known trends in Alzheimer’s disease staging on a population level, we observed that the high degree of heterogeneity between patients at baseline is also reflected in their seeds. Additionally, the individualized seeds are significantly more predictive of future atrophy than a single seed placed at the hippocampus. Our findings illustrate that understanding where disease originates in individuals is critical to determining how it progresses and that our method allows us to infer early stages of disease from atrophy patterns observed at diagnosis.
Predicting progression from normal cognition to mild cognitive impairment for individuals at 5 years Brain (IF 10.292) Pub Date : 2018-01-19 Marilyn Albert, Yuxin Zhu, Abhay Moghekar, Susumu Mori, Michael I Miller, Anja Soldan, Corinne Pettigrew, Ola Selnes, Shanshan Li, Mei-Cheng Wang
Recent evidence indicates that measures from cerebrospinal fluid, MRI scans and cognitive testing obtained from cognitively normal individuals can be used to predict likelihood of progression to mild cognitive impairment several years later, for groups of individuals. However, it remains unclear whether these measures are useful for predicting likelihood of progression for an individual. The increasing focus on early intervention in clinical trials for Alzheimer’s disease emphasizes the importance of improving the ability to identify which cognitively normal individuals are more likely to progress over time, thus allowing researchers to efficiently screen participants, as well as determine the efficacy of any treatment intervention. The goal of this study was to determine which measures, obtained when individuals were cognitively normal, predict on an individual basis, the onset of clinical symptoms associated with a diagnosis of mild cognitive impairment due to Alzheimer’s disease. Cognitively normal participants (n = 224, mean baseline age = 57 years) were evaluated with a range of measures, including: cerebrospinal fluid amyloid-β and phosphorylated-tau, hippocampal and entorhinal cortex volume, cognitive tests scores and APOE genotype. They were then followed to determine which individuals developed mild cognitive impairment over time (mean follow-up = 11 years). The primary outcome was progression from normal cognition to the onset of clinical symptoms of mild cognitive impairment due to Alzheimer’s disease at 5 years post-baseline. Time-dependent receiver operating characteristic analyses examined the sensitivity and specificity of individual measures, and combinations of measures, as predictors of the outcome. Six measures, in combination, were the most parsimonious predictors of transition to mild cognitive impairment 5 years after baseline (area under the curve = 0.85; sensitivity = 0.80, specificity = 0.75). The addition of variables from each domain significantly improved the accuracy of prediction. The incremental accuracy of prediction achieved by adding individual measures or sets of measures successively to one another was also examined, as might be done when enrolling individuals in a clinical trial. The results indicate that biomarkers obtained when individuals are cognitively normal can be used to predict which individuals are likely to develop clinical symptoms at 5 years post-baseline. As a number of the measures included in the study could also be used as subject selection criteria in a clinical trial, the findings also provide information about measures that would be useful for screening in a clinical trial aimed at individuals with preclinical Alzheimer’s disease.
Fibre-specific white matter reductions in Alzheimer’s disease and mild cognitive impairment Brain (IF 10.292) Pub Date : 2018-01-04 Remika Mito, David Raffelt, Thijs Dhollander, David N Vaughan, J-Donald Tournier, Olivier Salvado, Amy Brodtmann, Christopher C Rowe, Victor L Villemagne, Alan Connelly
Alzheimer’s disease is increasingly considered a large-scale network disconnection syndrome, associated with progressive aggregation of pathological proteins, cortical atrophy, and functional disconnections between brain regions. These pathological changes are posited to arise in a stereotypical spatiotemporal manner, targeting intrinsic networks in the brain, most notably the default mode network. While this network-specific disruption has been thoroughly studied with functional neuroimaging, changes to specific white matter fibre pathways within the brain’s structural networks have not been closely investigated, largely due to the challenges of modelling complex white matter structure. Here, we applied a novel technique known as ‘fixel-based analysis’ to comprehensively investigate fibre tract-specific differences at a within-voxel level (called ‘fixels’) to assess potential axonal loss in subjects with Alzheimer’s disease and mild cognitive impairment. We hypothesized that patients with Alzheimer’s disease would exhibit extensive degeneration across key fibre pathways connecting default network nodes, while patients with mild cognitive impairment would exhibit selective degeneration within fibre pathways connecting regions previously identified as functionally implicated early in Alzheimer’s disease. Diffusion MRI data from Alzheimer’s disease (n = 49), mild cognitive impairment (n = 33), and healthy elderly control subjects (n = 95) were obtained from the Australian Imaging, Biomarkers and Lifestyle study of ageing. We assessed microstructural differences in fibre density, and macrostructural differences in fibre bundle morphology using fixel-based analysis. Whole-brain analysis was performed to compare groups across all white matter fixels. Subsequently, we performed a tract of interest analysis comparing fibre density and cross-section across 11 selected white matter tracts, to investigate potentially subtle degeneration within fibre pathways in mild cognitive impairment, initially by clinical diagnosis alone, and then by including amyloid status (i.e. a positive or negative amyloid PET scan). Our whole-brain analysis revealed significant white matter loss manifesting both microstructurally and macrostructurally in Alzheimer’s disease patients, evident in specific fibre pathways associated with default mode network nodes. Reductions in fibre density and cross-section in mild cognitive impairment patients were only exhibited within the posterior cingulum when statistical analyses were limited to tracts of interest. Interestingly, these degenerative changes did not appear to be associated with high amyloid accumulation, given that amyloid-negative, but not positive, mild cognitive impairment subjects exhibited subtle focal left posterior cingulum deficits. The findings of this study demonstrated a stereotypical distribution of white matter degeneration in patients with Alzheimer’s disease, which was in line with canonical findings from other imaging modalities, and with a network-based conceptualization of the disease.
Effect of cholinergic treatment depends on cholinergic integrity in early Alzheimer’s disease Brain (IF 10.292) Pub Date : 2018-01-04 Nils Richter, Nora Beckers, Oezguer A Onur, Markus Dietlein, Marc Tittgemeyer, Lutz Kracht, Bernd Neumaier, Gereon R Fink, Juraj Kukolja
See Sultzer (doi:10.1093/brain/awy040) for a scientific commentary on this article.
MicroRNA132 associated multimodal neuroimaging patterns in unmedicated major depressive disorder Brain (IF 10.292) Pub Date : 2018-02-02 Shile Qi, Xiao Yang, Liansheng Zhao, Vince D. Calhoun, Nora Perrone-Bizzozero, Shengfeng Liu, Rongtao Jiang, Tianzi Jiang, Jing Sui, Xiaohong Ma
There is compelling evidence that epigenetic factors contribute to the manifestation of depression, in which microRNA132 (miR-132) is suggested to play a pivotal role in the pathogenesis and neuronal mechanisms underlying the symptoms of depression. Additionally, several depression-associated genes [MECP2, ARHGAP32 (p250GAP), CREB, and period genes] were experimentally validated as miR-132 targets. However, most studies regarding miR-132 in major depressive disorder are based on post-mortem, animal models or genetic comparisons. This work will be the first attempt to investigate how miR-132 dysregulation may impact covariation of multimodal brain imaging data in 81 unmedicated major depressive patients and 123 demographically-matched healthy controls, as well as in a medication-naïve subset of major depressive patients. MiR-132 values in blood (patients > controls) was used as a prior reference to guide fusion of three MRI features: fractional amplitude of low frequency fluctuations, grey matter volume, and fractional anisotropy. The multimodal components correlated with miR-132 also show significant group difference in loadings. Results indicate that (i) higher miR-132 levels in major depressive disorder are associated with both lower fractional amplitude of low frequency fluctuations and lower grey matter volume in fronto-limbic network; and (ii) the identified brain regions linked with increased miR-132 levels were also associated with poorer cognitive performance in attention and executive function. Using a data-driven, supervised-learning method, we determined that miR-132 dysregulation in major depressive disorder is associated with multi-facets of brain function and structure in fronto-limbic network (the key network for emotional regulation and memory), which deepens our understanding of how miR-132 dysregulation in major depressive disorders contribute to the loss of specific brain areas and is linked to relevant cognitive impairments.
Cerebral pneumography and the 20th century localization of brain tumours Brain (IF 10.292) Pub Date : 2018-02-06 Bart Lutters, Peter J Koehler
In 1918, the American neurosurgeon Walter Dandy (1886–1946) first described the injection of air into the cerebral ventricles as an aid to clinical diagnostics (Dandy, 1918). By revealing alterations in the shape, size or position of the ventricles on the radiogram, ventriculography provided a valuable tool to indirectly predict the presence and localization of brain tumours. The following year, Dandy introduced a method for the ‘intraspinous’ injection of air, pneumoencephalography, which allowed for the radiological visualization of tumour-induced changes of both the ventricular system and the cerebral subarachnoid space (Dandy, 1919). With the invention of ventriculography and pneumoencephalography—jointly referred to as cerebral pneumography—Dandy laid the groundwork for subsequent methods...
Unifying control over the body: consciousness and cross-cueing in split-brain patients Brain (IF 10.292) Pub Date : 2018-01-16 Lukas J Volz, Steven A Hillyard, Michael B Miller, Michael S Gazzaniga
No evidence for rare TRAP1 mutations influencing the risk of idiopathic Parkinson’s disease Brain (IF 10.292) Pub Date : 2018-01-24 Johannes J Gaare, Gonzalo S Nido, Paweł Sztromwasser, Per M Knappskog, Olav Dahl, Morten Lund-Johansen, Guido Alves, Ole-Bjørn Tysnes, Stefan Johansson, Kristoffer Haugarvoll, Charalampos Tzoulis
Reply: No evidence for rare TRAP1 mutations influencing the risk of idiopathic Parkinson’s disease Brain (IF 10.292) Pub Date : 2018-01-24 Julia C Fitzgerald, Alexander Zimprich, Dheeraj Reddy Bobbili, Manu Sharma, Patrick May, Rejko Krüger
High-dose spaced theta-burst TMS as a rapid-acting antidepressant in highly refractory depression Brain (IF 10.292) Pub Date : 2018-02-05 Nolan R Williams, Keith D Sudheimer, Brandon S Bentzley, Jaspreet Pannu, Katy H Stimpson, Dalton Duvio, Kirsten Cherian, Jessica Hawkins, Kristen H Scherrer, Benjamin Vyssoki, Danielle DeSouza, Kristin S Raj, Jennifer Keller, Alan F Schatzberg
Reply: High-dose spaced theta-burst TMS as a rapid-acting antidepressant in highly refractory depression Brain (IF 10.292) Pub Date : 2018-02-05 Cheng-Ta Li, Tung-Ping Su
‘All disease begins in the gut’: was Hippocrates right? Brain (IF 10.292) Pub Date : 2018-02-12 Louisa Lyon
When Mark Kahn and his team needed to transfer their mice to a new facility, they were worried that the move might disrupt their experiments. The group had been working with models of cerebral cavernous malformations—collections of enlarged and abnormally shaped capillaries that are vulnerable to haemorrhage, giving rise to seizures and stroke. In the old facility, mice with specific mutations had reliably developed lesions similar to the pathology seen in humans. So, when this phenotype suddenly disappeared following the move to the new facility, the group initially thought their fears had been realized. ‘But then came a piece of serendipity’, says Kahn, who is based at the University of Pennsylvania. ‘A small number of the mice developed a peritoneal abscess … And those animals were...
Erratum Brain (IF 10.292) Pub Date : 2017-12-09
Martina Minnerop, Delia Kurzwelly, Holger Wagner, Anne S. Soehn, Jennifer Reichbauer, Feifei Tao, et al. Hypomorphic mutations in POLR3A are a frequent cause of sporadic and recessive spastic ataxia. Brain 2017; 140: 1561–1578, https://doi.org/10.1093/brain/awx095.
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