Most compelling, however, are experiments that have demonstrated te relevance of optogenetics to both basic science and medicine. At the Society for Neuroscience meeting in Chicago last October, Michael Häusser of University College London reported on an optogenetics experiment that showed how 100 neurons could trigger a memory stored in a much larger ensemble of about 100,000 neurons, suggesting how the technique may be used to understand memory formation.
Last spring Deisseroth’s group published an optogenetics study that helped to elucidate the workings of deep-brain stimulation, which uses electrodes implanted deep in the brain to alleviate the abnormal movements of Parkinson’s disease. The experiment called into question the leading theory of how the technology works—activation of an area called the subthalamic nucleus. Instead the electrodes appear to exert their effects on nerve fibers that reach the subthalamic nucleus from the motor cortex and perhaps other areas. The finding has already led to a better understanding of how to deploy deep-brain electrodes. Given its fine-tuned specificity, optoelectronics might eventually replace deep-brain stimulation.
Although optogenetic control of human behavior may be years away, Deisseroth comments that the longer-range implications of the technology must be considered: “I’m not writing ethics papers, but I think about these issues every day, what it might mean to gain understanding and control over what is a desire, what is a need, what is hope.”
Note: this story was originally printed with the title "A Light in the Brain"