So cool, the how and the why of controlling neurons with light. First, the why. Current methods lack precision:
Drugs and implanted electrodes can influence the brain, but they are terribly imprecise: Drugs flood the brain and affect many types of neurons indiscriminately. Electrodes activate every neuron around them.
This is bad for researchers, because practically every square millimeter of the brain contains a mess of different kinds of neurons, each specialized for a particular task. Drugs and electricity set off cascades of unwanted neural activity. Side effects.
It’s bad for patients, too. Cochlear implants, which let the deaf hear by shocking the auditory nerves, produce fuzzy sound because the electricity spreads beyond the neurons it’s aimed at. Deep brain stimulators for Parkinson’s patients allow them to walk and speak but may cause seizures and muscle weakness. Electroshock can help depression but often results in memory loss.
But if you can shine a light on just the section of the brain you want to fire (or not fire) you can get great precision. Of course, neurons are not light sensitive. At all. The solution? Insert genes from plants, which ARE light sensitive, into the neurons. How to do that is yet another cool thing, as is the potential Parkinson’s treatment, but I’ll leave that for the article.
