Acknowledgement
The authors are grateful to Dr Jung Kim for her helpful comments and review of the manuscript. The authors would also like to thank Yury Gerasimenko, Jonathon Hodes, Joel Burdick, Claudia Angeli, Yangsheng Chen, Christie Ferreira, Andrea Willhite, Enrico Rejc and Robert G Grossman.
Financial & competing interests disclosure
The authors have received funding from the NIBIB (grant number: NIBIB 5R01EB7615), the Christopher and Dana Reeve Foundation ES1-2011(SH) and the NINDS R01 NS062009. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
No writing assistance was utilized in the production of this manuscript.