Optogenetics is a rapidly developing new technique that combines optical methods with techniques that are used in molecular biology. It can be used for monitoring various optical processes in cells and controlling their activity using light. The technique is based on bacterial opsin expression in mammalian neurons. In this review, the use of optogenetics for controlling the activity of specific neuronal populations in different regions of the human brain is considered in detail. The paper also presents information on light-sensitive proteins, genetically encoded optical instruments, and their use for activation or inhibition of neurons and investigation of the causal relationship between neural networks and pathological symptoms.