A second major focus is on devising ways of targeting important subtypes of neurons for expression of transgenes in the brains of animals that have not been genetically modified, with the eventual goal of allowing the use of our novel techniques in human patients. Therapies such as deep brain stimulation (DBS) can be life-changing for patients suffering from diseases such as Parkinson’s Disease, but it relies on nonspecific electrical stimulation of all neurons and processes within the vicinity of the electrode, often causing severe deleterious side effects. Neuroscience is far ahead of neurology in the precision with which neuronal populations can be stimulated: in the last decade, neuroscience has been revolutionized by the invention of “optogenetics”, or the control of neurons using light alone by means of special genes encoding “opsins” that can be expressed in the neurons to be controlled. Optogenetics is only useful, however, when the opsins can be specifically expressed in functionally meaningful groups of neurons, instead of nonspecifically within all types of neurons in a given part of the brain. Because the best current way of restricting opsin expression to specific neuron types is to use genetically modified rats and mice, this requirement has meant that optogenetics has so far been used almost exclusively in rodents, and has not been available for therapeutic purposes in human patients at all. We are currently engineering systems for targeting specific, functionally meaningful, and clinically important neuronal subtypes for expression of optogenetic genes. Our hope is that this will result in a new paradigm for targeted optogenetic deep brain stimulation in human patients.”
