A precise and minimally invasive approach to optogenetics in the awake primate

Optogenetics has proven to be a powerful tool for understanding the function of specific cell types and circuits within the central nervous system and establishing a causal link between their activity and behavior. Its application in non-human primates has been slow to develop. One challenge has been the damage caused by transdural delivery of viruses and light to the brain. Here, we report optogenetic activation of neuronal responses in the alert and behaving monkey after replacement of the native dura with a transparent artificial dura. This approach enables the use of fine glass micropipettes to inject virus with minimal damage and transdural illumination, obviating the damage that would otherwise occur as a result of lowering optical fibers into the brain. It also permits visualization of the underlying cortical micro-vasculature, which has proven to be helpful in targeting electrodes and laser illumination to the virus location. This approach promises to greatly assist in the dissection of cortical circuits underlying visual perception and behavior.