Tasks for inhibitory interneurons in intact brain circuits

•Inhibition secures transient autonomy of principal cells.•Inhibitory interneurons are the backbone of brain oscillations.•Optogenetics-assisted tagging of interneuron subtypes improves correlative studies.•Cell-type specific manipulations clarify the roles of interneurons in computation.

Synaptic inhibition, brought about by a rich variety of interneuron types, counters excitation, modulates the gain, timing, tuning, bursting properties of principal cell firing, and exerts selective filtering of synaptic excitation. At the network level, it allows for coordinating transient interactions among the principal cells to form cooperative assemblies for efficient transmission of information and routing of excitatory activity across networks, typically in the form of brain oscillations. Recent techniques based on targeted expression of neuronal activity modulators, such as optogenetics, allow physiological identification and perturbation of specific interneuron subtypes in the intact brain. Combined with large-scale recordings or imaging techniques, these approaches facilitate our understanding of the multiple roles of inhibitory interneurons in shaping circuit functions.This article is part of the Special Issue entitled 'GABAergic Signaling in Health and Disease'.