As I have followed the story of bacteriorhodopsin - the biological computer that never happened - for many years now, I was very pleased to learn that somebody found something very clever to do with this and similar microbial opsins. Specifically, the recently developed methodology of "optogenetics" involves expressing microbial light-responsive ion channels or pumps in neurons, meaning that one can activate or inactivate these neurons by shining light of a certain wavelength onto them.
Stanford researcher and practicing psychiatrist Karl Deisseroth, who invented the method and pioneered its use, is keen to apply it directly to psychiatric questions. Others think a few fundamental things need to be sorted out first. Read more about all this in my feature, which is out in today's issue of Current Biology:
Shining new light on the brain
Current Biology, Volume 21, Issue 20, R831-R833, 25 October 2011
Summary and free access to PDF file