Snapshots of the Brain in Action: Local Circuit Operations through the Lens of γ Oscillations

gamma oscillations (20-80 Hz) are associated with sensory processing, cognition, and memory, and focused attention in animals and humans. gamma activity can arise from several neural mechanisms in the cortex and hippocampus and can vary across circuits, behavioral states, and developmental stages. gamma oscillations are nonstationary, typically occurring in short bouts, and the peak frequency of this rhythm is modulated by stimulus parameters. In addition, the participation of excitatory and inhibitory neurons in the gamma rhythm varies across local circuits and conditions, particularly in the cortex. Although these dynamics present a challenge to interpreting the functional role of gamma oscillations, these patterns of activity emerge from synaptic interactions among excitatory and inhibitory neurons and thus provide important insight into local circuit operations.