ReviewParsing the Network Mechanisms of Electroconvulsive Therapy
Section snippets
Hippocampal Plasticity After ECT: Epiphenomenon or Core Mechanism?
Increased hippocampal gray matter after ECT is robust and highly replicated across independent MRI studies (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29) and meta-/mega-analyses (30, 31, 32, 33,35), with larger effect sizes compared with other brain structures (35). Neuroimaging studies have also noted changes in hippocampal function using blood oxygen level–dependent and arterial spin-labeled fMRI, PET, and SPECT (45,47,63,64), as well as changes in metabolites with magnetic
Relevance of Seizure Physiology
ECT and other seizure therapies are unique among brain stimulation treatments, because in addition to the exogenous electrical (or other) stimulus, they activate a kind of endogenous stimulus, a generalized tonic-clonic (convulsive) seizure. Thus, each ECT session involves a cascade of neurofunctional events, beginning with general anesthesia, application of the electrical stimulus, the initiation, generalization, and termination of the seizure, and ending with postictal recovery. Each of these
Network Model of Seizure Therapy
The neurobiology of depression is widely thought to involve circuit-level dysfunction in corticolimbic networks, including structures such as the hippocampus and amygdala (52,53). Based on the neuroimaging evidence discussed here, we propose that seizure therapies improve symptoms by correcting or resetting this dysfunction, through the action of cerebellar-thalamo-cortical circuits on these dysfunctional corticolimbic circuits (Figure 4). During seizure initiation, the electrical stimulus
Conclusions
In this review, we have discussed evidence suggesting that subregional changes within MTL and associated cortical-limbic networks could be core mechanisms of successful antidepressant response to ECT (46, 47, 48,92). We also discussed evidence that networks relevant to seizure physiology could be important to ECT outcomes, particularly networks involving the thalamus and cerebellum (45,56,99,135). Despite the questions that remain, it is notable and potentially significant that such a
Acknowledgments and Disclosures
This work was supported by the National Institutes of Health (Grant Nos. R01MH092301 and U01MH110008 [to KLN and RE], R03MH121769 [to AML], K24MH102743 [to KLN], and K99MH119314 [to BW]), Muriel Harris Chair (Geriatric Psychiatry) (to RE), Brain and Behavior Research Foundation including 2015 & 2020 Young Investigator award (to AML), and 2018 Young Investigator award (to BW).
The authors report no biomedical financial interests or potential conflicts of interest.
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2023, Progress in Brain ResearchAttenuated interoceptive processing in individuals with major depressive disorder and high repetitive negative thinking
2022, Journal of Psychiatric ResearchCitation Excerpt :Current efforts seeking to target circumscribed brain circuits purported to underlie depression as a full syndrome have met with relatively disappointing results, including failed randomized, double-blind clinical trials of deep-brain stimulation (Dougherty, 2018). However, approaches involving the careful parsing of depression symptom dimensions and the neural circuits subserving them may hold promise as an intermediate step in developing new antidepressant techniques (Conroy and Holtzheimer, 2021; Leaver et al., 2022). Repetitive negative thinking (RNT) is a transdiagnostic manifestation commonly referred to as rumination in MDD, and it displays trait-like characteristics, contributing to poor outcomes in this disorder (Ehring and Watkins, 2008).
Nodal degree changes induced by electroconvulsive therapy in major depressive disorder: Evidence in two independent cohorts
2022, Journal of Affective DisordersCitation Excerpt :Recent neuroimaging studies have documented dysregulated brain networks are recognized as important mediators of MDD, including the affective network (AN), the default mode network (DMN), and frontoparietal network (FPN), which involved in emotional processing and top-down cognitive and emotional regulation processes (Brakowski et al., 2017; Kaiser et al., 2015; Mulders et al., 2015). Correspondingly, modulation of various cerebral networks were observed during ECT (Leaver et al., 2021a; Wang et al., 2018; Zhang et al., 2020). Leaver et al. tracked changes in separate hippocampal subregions and hippocampal networks linked with antidepressant response of ECT (Leaver et al., 2021b).