Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Brief Communication
  • Published:

Deep brain optogenetics without intracranial surgery

Abstract

Achieving temporally precise, noninvasive control over specific neural cell types in the deep brain would advance the study of nervous system function. Here we use the potent channelrhodopsin ChRmine to achieve transcranial photoactivation of defined neural circuits, including midbrain and brainstem structures, at unprecedented depths of up to 7 mm with millisecond precision. Using systemic viral delivery of ChRmine, we demonstrate behavioral modulation without surgery, enabling implant-free deep brain optogenetics.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Deep transcranial photoactivation.
Fig. 2: Towards deep transcranial optogenetics without cranial surgery.

Similar content being viewed by others

Data availability

The data that support the findings of this study are available upon reasonable request.

Code availability

Analysis code will be made available upon reasonable request.

References

  1. Won, S. M., Song, E., Reeder, J. T. & Rogers, J. A. Emerging modalities and implantable technologies for neuromodulation. Cell 181, 115–135 (2020).

    Article  CAS  Google Scholar 

  2. Cagnan, H., Denison, T., McIntyre, C. & Brown, P. Emerging technologies for improved deep brain stimulation. Nat. Biotechnol. 37, 1024–1033 (2019).

    Article  CAS  Google Scholar 

  3. Dayan, E., Censor, N., Buch, E. R., Sandrini, M. & Cohen, L. G. Noninvasive brain stimulation: from physiology to network dynamics and back. Nat. Neurosci. 16, 838–844 (2013).

    Article  CAS  Google Scholar 

  4. Tye, K. M. & Deisseroth, K. Optogenetic investigation of neural circuits underlying brain disease in animal models. Nat. Rev. Neurosci. 13, 251–266 (2012).

    Article  CAS  Google Scholar 

  5. Yizhar, O., Fenno, L. E., Davidson, T. J., Mogri, M. & Deisseroth, K. Optogenetics in neural systems. Neuron 71, 9–34 (2011).

    Article  CAS  Google Scholar 

  6. Deisseroth, K. & Hegemann, P. The form and function of channelrhodopsin. Science 357, eaan5544 (2017).

    Article  Google Scholar 

  7. Chen, R., Canales, A. & Anikeeva, P. Neural recording and modulation technologies. Nat. Rev. Mater. 2, 16093 (2017).

    Article  CAS  Google Scholar 

  8. Gradinaru, V. et al. Targeting and readout strategies for fast optical neural control in vitro and in vivo. J. Neurosci. 27, 14231–14238 (2007).

    Article  CAS  Google Scholar 

  9. Lin, J. Y., Knutsen, P. M., Muller, A., Kleinfeld, D. & Tsien, R. Y. ReaChR: a red-shifted variant of channelrhodopsin enables deep transcranial optogenetic excitation. Nat. Neurosci. 16, 1499–1508 (2013).

    Article  CAS  Google Scholar 

  10. Bedbrook, C. N. et al. Machine learning-guided channelrhodopsin engineering enables minimally invasive optogenetics. Nat. Methods 16, 1176–1184 (2019).

    Article  CAS  Google Scholar 

  11. Zhang, F. et al. Red-shifted optogenetic excitation: a tool for fast neural control derived from Volvox carteri. Nat. Neurosci. 11, 631 (2008).

    Article  Google Scholar 

  12. Gong, X. et al. An ultra-sensitive step-function opsin for minimally invasive optogenetic stimulation in mice and macaques. Neuron 107, 38–51 (2020).

    Article  CAS  Google Scholar 

  13. Marshel, J. H. et al. Cortical layer–specific critical dynamics triggering perception. Science 365, eaaw5202 (2019).

    Article  CAS  Google Scholar 

  14. Rajasethupathy, P. et al. Projections from neocortex mediate top-down control of memory retrieval. Nature 526, 653–659 (2015).

    Article  CAS  Google Scholar 

  15. Stujenske, JosephM., Spellman, T. & Gordon, JoshuaA. Modeling the spatiotemporal dynamics of light and heat propagation for in vivo optogenetics. Cell Rep. 12, 525–534 (2015).

    Article  CAS  Google Scholar 

  16. Owen, S. F., Liu, M. H. & Kreitzer, A. C. Thermal constraints on in vivo optogenetic manipulations. Nat. Neurosci. 22, 1061–1065 (2019).

    Article  CAS  Google Scholar 

  17. Tsai, H.-C. et al. Phasic firing in dopaminergic neurons is sufficient for behavioral conditioning. Science 324, 1080–1084 (2009).

    Article  CAS  Google Scholar 

  18. Berényi, A., Belluscio, M., Mao, D. & Buzsáki, G. Closed-loop control of epilepsy by transcranial electrical stimulation. Science 337, 735–737 (2012).

    Article  Google Scholar 

  19. Krook-Magnuson, E., Armstrong, C., Oijala, M. & Soltesz, I. On-demand optogenetic control of spontaneous seizures in temporal lobe epilepsy. Nat. Commun. 4, 1376 (2013).

    Article  Google Scholar 

  20. Vormstein-Schneider, D. C. et al. Viral manipulation of functionally distinct neurons from mice to humans. Nat. Neurosci. https://doi.org/10.1038/s41593-020-0692-9 (2020).

  21. Cho, K. K. et al. Gamma rhythms link prefrontal interneuron dysfunction with cognitive inflexibility in Dlx5/6+/− mice. Neuron 85, 1332–1343 (2015).

    Article  CAS  Google Scholar 

  22. Chan, K. Y. et al. Engineered AAVs for efficient noninvasive gene delivery to the central and peripheral nervous systems. Nat. Neurosci. 20, 1172 (2017).

    Article  CAS  Google Scholar 

  23. Walsh, J. J. et al. 5-HT release in nucleus accumbens rescues social deficits in mouse autism model. Nature 560, 589–594 (2018).

    Article  CAS  Google Scholar 

  24. Matthews, G. A. et al. Dorsal raphe dopamine neurons represent the experience of social isolation. Cell 164, 617–631 (2016).

    Article  CAS  Google Scholar 

  25. Armstrong, C., Krook-Magnuson, E., Oijala, M. & Soltesz, I. Closed-loop optogenetic intervention in mice. Nat. Protoc. 8, 1475–1493 (2013).

    Article  CAS  Google Scholar 

  26. Choi, H. M. et al. Third-generation in situ hybridization chain reaction: multiplexed, quantitative, sensitive, versatile, robust. Development 145, dev165753 (2018).

    Article  Google Scholar 

Download references

Acknowledgements

We thank C. Bedbrook, M. Lovett-Barron and L. Tan for feedback on the manuscript and the entire Deisseroth laboratory for advice and discussions. We also thank T. Gschwind for assistance with EEG analysis. This research was supported by grants from the NIH, NSF, Gatsby, Fresenius, Wiegers, Grosfeld and NOMIS Foundations (to K.D.); a Walter V. and Idun Berry Postdoctoral Fellowship, and grant K99 DA050662 (to F.G.); a NARSAD Young Investigator Grant (to R.C. and to F.G.); grant F32 NS106764 (to Q.A.N.); grants R01 NS112518 and R01 NS104071 and the University of Minnesota’s MnDRIVE (Minnesota’s Discovery, Research and Innovation Economy) initiative (to E.K.-M.); and grant NS94668 (to I.S.).

Author information

Authors and Affiliations

Authors

Contributions

R.C. and K.D. designed the experiments and wrote the paper with comments from all other authors. F.G. performed electrophysiology experiments and analysis. R.C. and Q.A.N. performed closed-loop EEG and optogenetic experiments and analysis with input from E.K.-M. and I.S. R.C., F.G., Q.A.N., S.P., S.H.K., M.R. and B.H. performed animal surgeries, behavior, behavioral analysis and histology. Y.S.K. performed patch clamp recordings and analysis. C.R. designed and generated constructs for viruses. K.D. supervised all aspects of the work.

Corresponding author

Correspondence to Karl Deisseroth.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Extracellular electrophysiological characterization of transcranial deep brain optogenetics at different photostimulation parameters in mice.

a, Confocal image of representative neurons in the VTA expressing either soma-localized (Kv2.1) or non-localized ChRmine-oScarlet. Scale bar: 100 µm. b, Representative peristimulus time histogram of transcranial light-evoked spikes at different pulse widths. Light-responsive single-unit neural recordings at different pulse widths plotted as: probability of one or more evoked spikes (c), number of spikes per pulse (d), and latency to the first spike (e) (n = 7 units from 2 mice; one-way ANOVA with Bonferroni post hoc tests: F(3,24) = 22.51, P = 0.0000004 (c); F(3,22)=2.10, P= 0.13 (d); and F(3,22) = 9.30, P = 0.0004 (e). Note two neurons exhibited no spike response at 1-ms pulse width and therefore do not have an associated latency or spike count at this pulse width). f, Representative peristimulus time histogram of transcranial light-evoked spikes at different frequencies. Light-responsive single-unit neural recordings at different frequencies plotted as: probability of one or more evoked spikes (g), number of spikes per pulse (h), and latency to the first spike (i) (n = 7 from 2 mice; one-way ANOVA with Bonferroni post hoc tests: F(3,24) = 6.31, P = 0.003 (g); F(3,24) = 2.82, P = 0.06 (h); and F(3,24)=0.52, P = 0.67 (i)). j, Representative raster plot and peristimulus time histogram of transcranial light-evoked spikes at low light power (40 mW mm-2, 100 ms duration). Light-responsive single-unit neural recordings at different irradiance (I) with an extended pulse width of 100 ms plotted as: probability of one or more evoked spikes (k), number of spikes per pulse (l), and latency to the first spike (m) (n = 12 units from 2 mice; one-way ANOVA with Bonferroni post hoc tests: (k) F(5,66) = 10.46, P = 0.0000002 (l) F(5,56) = 2.81, P = 0.02, and (m) F(5,56 ) = 14.08, P = 0.000000006. Note six (4 mW mm-2) and four (12 mW mm-2) neurons exhibited no spike response and therefore do not have an associated latency or spike count at these irradiances). n, Latency to first spike determined from patch recordings of cultured hippocampal neurons at low irradiance exhibiting increased time to fire action potentials with decreasing photon density (n = 5 neurons, one-way ANOVA with Bonferroni post hoc tests: F(2,12) = 36, P = 0.03). Light-responsive single-unit neural recordings at different irradiance for ChRmine-expressing neurons with (nonstriped) or without (striped) the Kv2.1 peptide tag:probability of one or more evoked spikes (o), number of spikes per pulse (p), and latency to the first spike (q) (n = 7 units from 2 mice (ChRmine) and n = 7 units from 2 mice (ChRmine-Kv2.1); two-way ANOVA with Bonferroni post hoc tests: ChRmine-Kv2.1 vs ChRmine (o) F(1,48)=0.02, P=0.88, (p) F(1,43)=0.08, P=0.78, and (q) F(1,43)=0.42, P=0.52). No differences in the ability to photoactivate neurons with or without the Kv2.1 tag was observed. In be, 635 nm light was delivered at 10 Hz and 800 mW mm-2 light power at different pulse width. In fi, 635 nm light was delivered at 800 mW mm-2 mW light power with 5-ms pulse width at different frequencies. In jm, 635 nm light was delivered at 1 Hz with 100 ms pulse at different irradiance. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; NS, not significant. Data are mean ± sem.

Extended Data Fig. 2 ChRmine photoactivatable up to 7 mm from the skull.

a, Schematic of experiment for extracellular recording in anesthetized rats. b, Confocal image of a coronal slice from rat depicting DAPI-stained cells (blue) and soma-localized ChRmine-oScarlet-Kv2.1 (red) expression in neurons at 6 mm (left) and 7 mm (right). Inset: expanded view of neurons expressing ChRmine. Scale bar: 1 mm, (inset) 100 µm. c, d, Example voltage trace of light-evoked activity in response to 5-ms pulse width of light delivered at 10 Hz with a 635 nm laser at 800 mW mm-2. Light-responsive single-unit neural recordings at 6 mm plotted as: probability of one or more evoked spikes (e), number of spikes per pulse (f), and latency to the first spike (g) (n = 15 units from 2 rats). Light-responsive single-unit neural recordings at 7 mm plotted as: probability of one or more evoked spikes (h), number of spikes per pulse (i), and latency to the first spike (j) (n = 6 units from 2 rats). In eg and hj, 635 nm light was delivered at 1 Hz with a pulse width of 100 ms at different irradiance (I). At 400 mW mm-2, these conditions resulted in a spike probability of 0.96 with an average spike latency of 27 ± 6 ms and a spike count of 3.7 ± 0.6 recorded at 6 mm in depth, and a spike probability of 0.97 with an average spike latency of 39 ± 7 ms and a spike count of 3 ± 0.6 at 7 mm in depth. At the same conditions, no light-evoked activity was recorded at 8 mm deep across 2 rats. Data are mean ± sem.

Extended Data Fig. 3 ChRmine enabled transcranial deep brain optogenetics at light powers that elicit minimal tissue heating.

a, Light transmission profile through brain tissue from a 400-µm 0.39 NA optical fiber calculated from Monte Carlo simulations of photon propagation. b, Calculated maximum temperature change associated with a 635 nm laser delivered at various light powers and frequencies with a pulse width of 5 ms. Note conditions used for transcranial optogenetics in mice (800 mW mm-2 and up to 10% duty cycle) resulted in minimal tissue heating at steady state (~0.3 °C, gray dashed line). c, Calculated maximum temperature change associated with a 635 nm laser delivered at various light powers as a function of continuous irradiation time. Note conditions used for transcranial optogenetics in rats (400 mW mm-2 with 100-ms pulse width at 1 Hz) resulted in minimal tissue heating at steady state (~0.4 °C, gray dashed line). d, Modeled temperature distribution in brain tissue at steady state for 635 nm light delivered at 800 mW mm-2, 20 Hz, 5-ms pulse width. e, Calculated maximum temperature change for various laser parameters used for transcranial optogenetics applied for 10 s (see Supplementary Table 2 for summary of parameters). Note stimulation conditions for ChRmine (red) heat tissue less than range reported to have nonspecific temperature effects on behavior (green, 532 nm 222 mW mm-2). Percentage of Iba+ microglia (f) and GFAP+ astrocytes (g) among DAPI-labeled cells within 200 µm of fiber optic source on the photostimulated (ipsilateral, red) or non-photostimulated (contralateral, gray) side. 635 nm light was delivered at 20 Hz with 5 ms pulse at different light powers (800, 3200, and 6400 mW mm-2) for 1 hour. Animals were perfused 24 hours after photostimulation. No glial accumulation was evident at 800 mW mm-2 and 10% duty cycle conditions (n = 3 mice; two-sided paired t-test, *P = 0.03; **P = 0.005; NS, not significant). h, Representative confocal image depicting a coronal slice treated at 6400 mW mm-2 exhibiting tissue lesioning on the ipsilateral side. i, Representative confocal images with indicated side of photostimulation and irradiance. Scale bar: 100 µm. Data are mean ± sem.

Extended Data Fig. 4 Evaluation of long-term expression of ChRmine at 7 months.

a, DAT-Cre mice following 7 months of ChRmine-oScarlet expression were subjected to a real-time place preference test with stimulation parameters at 800 mW mm-2, 500 ms ON/OFF at 20 Hz with 5-ms pulse width (5% duty cycle) (n = 5 mice; two-sided paired t-test, P = 0.003). b, Representative images of cFos expression with (bottom) or without (top) stimulation. Scale bar: 100 µm. c, Percentage of cFos+ cells among DAPI-labeled cells in the VTA. Mice were sacrificed 90 minutes following 10 minutes of transcranial photostimulation at 0 or 800 mW mm-2 laser delivered at 20 Hz and 5-ms pulse width (n = 3 per group; two-sided unpaired t-test, P = 0.001). d, Representative confocal image of neurons in the VTA expressing ChRmine-oScarlet (red fluorescent protein (FP)), stained with DAPI (blue, separate channel not shown), Iba1+ microglia (magenta), and GFAP+ astrocytes (white) used to assess glia distribution within the injection (ipsilateral) and contralateral side. Scale bar: 1 mm and 100 µm. Percentage of astrocytes (e) and microglia (f) among DAPI-labeled cells. No statistical difference in glial accumulation was observed in the VTA with (ipsilateral) or without (contralateral) local ChRmine expression (n = 3 per group; two-sided unpaired t-test, P = 0.38 (e and f)). **P < 0.01; NS, not significant. Data are mean ± sem.

Extended Data Fig. 5 Transcranial photoactivation of ChRmine enabled functional control of dopaminergic neurons.

DAT-Cre mice with ChRmine-oScarlet expression in dopaminergic neurons were subjected to a real-time place preference test. Percent of time spent on the stimulation side receiving transcranial photostimulation with the following parameters: a, tonic (1 Hz) or phasic (20 Hz) stimulation delivered at 800 mW mm-2 and 5-ms pulse width; b, with and without stimulation at 40 mW mm-2 delivered at 5 Hz with 100-ms pulse width (n=5 mice; two-sided paired t-test, P = 0.018 (a); P = 0.023 (b)). c, DAT-Cre mice expressing bReaChES did not exhibit place preference even at irradiance (I) of 3200 mW mm-2, 500 ms ON/OFF, 20 Hz and 5-ms pulse width (n = 4 mice (bReaChES), n = 6 mice (ChRmine); one-way repeated-measure ANOVA: F(4,12)=1.15, P = 0.38 (bReaChES) and two-sided paired t-test (ChRmine), P = 0.02). d, Representative confocal images of neurons in the VTA expressing red fluorescent protein and/or the indicated opsin (red) stained with DAPI (blue) and cFos (white). Scale bar: 100 µm. e, Percentage of cFos+ cells among DAPI-labeled cells in the VTA following 10 minutes of transcranial photostimulation at 20 Hz and 800 mWmm-2 with 5-ms pulse width. Animals were sacrificed after 90 minutes (n = 4 per group; one-way ANOVA with Bonferroni post hoc tests: F(3,12) = 14.24, P = 0.0003). *P < 0.05; **P < 0.01; NS, not significant. Data are mean ± sem.

Extended Data Fig. 6 Evaluation of cell type specificity for seizure inhibition.

Representative confocal image of the hippocampus depicting ChRmine-YFP (white) neurons co-stained with DAPI (blue), the vesicular GABA transporter VGAT (cyan), and parvalbumin PV (magenta) regulated by either the E2 enhancer derived from the Scna1 gene (a) or the Dlx5/6 enhancer (b). Scale bar: 1 mm and (expanded view) 100 µm. White arrows point to YFP+/VGAT+/PV+ neurons while proximal ‘*’ indicate YFP+/VGAT+/PV- neurons. Pie chart depicts quantification of YFP+ cells regulated by the E2 (a) or Dlx5/6 (b) enhancer that are either eYFP+/VGAT+/PV+ (magenta), eYFP+/VGAT+/PV- (cyan), or eYFP+/VGAT-/PV- (grey). Note all PV+ neurons were also VGAT+ and that a subset of YFP+ neurons (3% (E2) and 10% (Dlx5/6)) were not labeled by the VGAT GABAergic marker. A total of 302 and 227 neurons were counted from 3 (E2) and 4 (Dlx5/6) mice respectively. c, Comparison of mean seizure distribution without light stimulation showed comparable seizure duration across cohorts (n = 4 per group; one-way ANOVA: F(2,9)=0.56, P = 0.59). Data are mean ± sem. Box plot of each animal from E2::ChRmine-eYFP (d), Dlx5/6::ChRmine-eYFP (e) and Dlx5/6::eYFP (f) cohorts depicting seizure duration from trigger with (filled) and without (not filled) light treatment (n = 4 mice per group; two-sided Mann-Whitney U Test). Each box denotes lower (25%) and upper (75%) quartile with median (line) and mean (square) and whiskers depict the 10-90% range for all measured seizures. *P < 0.05; **P < 0.01; ***P < 0.01; ****P < 0.0001; NS, not significant.

Extended Data Fig. 7 Effects of brain-noninvasive transcranial activation of 5-HT neurons on novelty preference, anxiety-related behaviors, and induction of the neural activity marker cFos.

a, Mice were assessed for novelty preference by quantifying ratio of time spent in the chamber containing a novel object relative to time spent in the empty chamber with and without photostimulation for YFP (gray) and ChRmine-eYFP (red) mice. Stimulation does not alter novel object interaction (n = 8 mice; two-sided paired t-test). b, Mice were assessed for anxiety-related behavior with a 15 min open field test, where the first and last 5 min block were not paired with light stimulation (OFF), while the middle 5 min was paired with 635 nm stimulation (800 mW mm-2, 20 Hz, 5-ms pulse width repeated in 10 s intervals). Stimulation does not alter anxiety-behavior based on time spent in the center of the arena. (n = 8 mice; repeated-measure one-way ANOVA: F(2,14) = 2.23, P = 0.15 (eYFP) and F(2,14) = 0.05, P = 0.83 (ChRmine-eYFP)). c, Example path-tracing of a 5-HT ChRmine-YFP mouse during the 3 5-min blocks of the 15 min long open field test. Tracks are color coded for velocity (v). d, Representative confocal image of ChRmine-YFP neurons (white) in the raphe stained for cFos (magenta) by in situ hybridization and DAPI (blue). White arrows point to example YFP+/cFos+ neurons. Scale bar: 100 µm and (expanded view) 10 µm. e, Percentage of cFos+ cells among DAPI-labeled cells in the raphe following 10 min of transcranial photostimulation at 20 Hz and 800 mW mm-2 with 5-ms pulse width. (n = 4 per group; one-way ANOVA: F(1,6)=16, P = 0.007). **P < 0.01; NS, not significant. Data are mean ± sem.

Extended Data Fig. 8 Comparison of expression level and photoactivity of ChRmine-expressing neurons targeted by intracranial or retro-orbital delivery.

a, Confocal images of Purkinje neurons expressing eYFP (white) co-labeled with in situ hybridization for ChRmine mRNA (magenta). Neurons were targeted by AAVPHP.eB-L7::ChRmine-p2a-eYFP by direct or retro-orbital injection. Scale bar: 100 µm. Box plot of mean intensity signal from individual neurons for (b) eYFP and (c) ChRmine mRNA (n = 2 mice, 60 neurons per group; two-sided unpaired t-test, P = 6.7e-10 (eYFP), 5.2e-10 (ChRmine mRNA)). The mean signal of neurons targeted by retro-orbital injection was 42% (eYFP) and 34% (ChRmine mRNA) relative to the signal from direct injection, indicative of the lower multiplicity of infection. Each box denotes lower (25%) and upper (75%) quartile with median (line) and mean (square) and whiskers depict the 10-90% range for neurons quantified. In vivo extracellular recordings at 3 mm from skull following transcranial stimulation from neurons expressing ChRmine targeted by intracranial (not filled) or retro-orbital (gray) injections plotted as: probability of one or more evoked spikes (d); number of spikes per pulse (e); and latency to the first spike (f) across the population of neurons as a function of irradiance (I) delivered at 10 Hz with 5-ms pulse width. No statistically significant difference was observed in single-unit response between the viral delivery methods (n = 9 units from 2 mice (intracranial) and n = 10 units from 2 mice (retro-orbital); two-way ANOVA with Bonferroni post hoc tests: intracranial vs. retro-orbital F(1,85) = 0.002, P = 0.96 (d); F(1,83) = 0.05, P = 0.82 (e); and F(1,83) = 0.65, P = 0.42 (f). Note one neuron in each group exhibited no spike response at 80 mW mm-2 and as such has no corresponding spike count or latency at this irradiance). ****P < 0.0001; NS, not significant. Data are mean ± sem.

Supplementary information

Supplementary Information

Supplementary Note 1 and Tables 1 and 2.

Reporting Summary

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Chen, R., Gore, F., Nguyen, QA. et al. Deep brain optogenetics without intracranial surgery. Nat Biotechnol 39, 161–164 (2021). https://doi.org/10.1038/s41587-020-0679-9

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41587-020-0679-9

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing