Optogenetics in psychiatric diseases

•Optogenetics allows manipulation of neuronal circuits using unprecedented specificity and temporal resolution.•Optogenetics has identified networks in structures that play opposite roles in behavior such as reinforcement and aversion.•Opsin targeting to neurons using retrogradely transported viral vectors reveals new circuits regulating anxiety and depression.•Real-time readout technologies may set the stage for precise closed-circuit control and therapeutic intervention in human disease.

Optogenetic tools have revolutionized the field of neuroscience, and brought the study of neural circuits to a higher level. Optogenetics has significantly improved our understanding not only of the neuronal connections and function of the healthy brain, but also of the neuronal changes that lead to psychiatric disorders. In this review, we summarize recent optogenetic studies that explored different brain circuits involved in natural behaviors, such as sleep and arousal, reward, fear, and social and aggressive behavior. In addition, we describe how alterations in these circuits may lead to psychiatric disorders such as addiction, anxiety, depression, or schizophrenia.