Issue link: http://cp.revolio.com/i/1161
23 WWW.HPLusmAGAzINe.COm and photosynthesis. In a neuron, that activation fi res the cell. The second is from an archaeon, a salt-based extremophile, which responds to yellow light by pumping chloride ions. In a brain cell, that means not fi ring at all. To get the genes in place, Deisseroth's team opens up the skull and uses a pipette to apply a non- reproducing adenovirus to the desired brain area. The virus is genetically confi gured to inject both genes into a single cell type. The single cell will take both genes. After the "light switch" genes are in place, those brain cells are now light sensitive and a 50 micrometer fi ber optic cable is fed to the area. In this way, they can target very specifi c deep brain structures, areas currently too deep and fragile for most psychosurgery. Once the researcher attaches the other end of the cable to a laser, he or she has absolute and fl awless control over that group of neurons: blue light on, yellow light off. Dr. Deisseroth is a psychiatrist as well as bioengineer, and he envisions using optogenetics in place of DBs's not-so-deep cousin, Vagus Nerve stimulation. much like DBs, VNs uses an electrode to treat depression and epilepsy but targets where the vagus nerve passes through the neck rather than deep in the brain. It can still cause problems in many patients — sleep apnea, throat pain, coughing, and voice changes are the main complaints. Deisseroth believes optogenetics might be a way of reducing the side effects of VNs by targeting the treatments, rather than just shocking the neck region. All this points to easier and more effective neural control. We're still far from knowing which cells do what, and further from orchestrating treatments and enhancements for specifi c conditions. But for the fi rst time we can map and build useful handles on the very things that make us ourselves. Quinn Norton covers science, technology, law and whatever else gets her attention. she lives in Washington D.C. and is most easily reachable at quinn@quinnnorton.com