Figure 1. Overview of methods to optically stimulate neuronal populations.

A, single‐photon uncaging indiscriminately activates multiple populations of neurons within the local network. Firing (red trace) is induced in all neurons within the spatial extent of the light beam. B, two‐photon uncaging selectively activates individual neurons with single cell resolution. Firing (red trace) can be induced in target cells, but not adjacent neurons. C, single‐photon optogenetics selectively activates multiple neurons within the local network. Firing (red trace) is induced in all neurons within the spatial extent of the light beam so long as they express the construct encoding the optogenetic actuator. D, two‐photon optogenetics selectively activates individual neurons with single cell resolution. Firing (red trace) can be induced in the target cell, but not adjacent neurons, so long as target neurons express the construct encoding the optogenetic actuator.