👉🏻Optogenetics – the use of 👉🏻optically-activated proteins👈🏻 to 👉🏻control 👉🏻neuronal function – is a recent development in neuroscience methodology. Optogenetic techniques provide a means of 👉🏻activating or 👉🏻inhibiting distinct populations of 👉🏻neurons with an unprecedented degree of spatial, temporal, and neurochemical precision. Channelrhodopsin-2 (ChR2), an algal protein👈🏻 from Chlamydomonas reinhardtii, is a 👉🏻light-activated cation channel capable of inducing👈🏻👉🏻 depolarization and 👉🏻action potentials in neurons.