Abstract
The neuronal circuits in the brain of animals consist of diverse types of neurons that are interconnected
with each other at synaptic sites. Electrical stimulation has been conventionally used for the direct
stimulation of neurons in neurophysiological studies, although the limited spatial and temporal precision
inherent in the method has left neuroscientists eager for alternatives. The advent of single-component
light-activated cation channels from unicellular green algae, channelrhodopsins, has opened new
opportunities in neuroscience for the temporally and spatially precise control of neurons with light. The
experimental utility of the photostimulation method, which is called optogenetics, would revolutionize
basic neuroscience and the gene therapy of such neuronal disorders as Parkinson’s disease,
neuropsychiatric diseases, and vision malfunctions.
