The most commonly used ion channel for stimulation in optogenetics is Channelrhodopsin-2. Neurons are triggered in the same way (by moving ions from outside the cell to the inside). Once a certain number of positive ions have crossed the cell membrane, a threshold is reached which causes the neuron to fire.

Optogenetics enables manipulation of biological processes with light at high spatio-temporal resolution to control the behavior of cells, networks, or even whole animals.