Sohal et al recently developed an optogenetic technique to express a microbial opsin (Natronomonas pharaonis halorhodopsin; eNpRH) in parvalbumin neurons of mice to elucidate their role in neocortical processing. After flashes of yellow light were administered in vivo to inhibit the parvalbumin neurons, gamma oscillation power diminished 20 +/4%. Further tests with in vitro cortical slices confirmed the functional synergy of parvalbumin neurons with gamma oscillations. This synergy could amplify signals correpsonding to various focal stimuli, helping the transfer of information between brain circuits. Chalk up another impressive piece of work for Deisseroth’s lab.
Sohal VS, et al. Parvalbumin neurons and gamma rhythms enhance cortical circuit performance. Nature 459, 698-702. doi:10.1038/nature07991.