Rapid Rebalancing of Excitation and Inhibition by Cortical Circuitry.

Excitation is balanced by inhibition to cortical neurons across a wide range of conditions. To understand how this relationship is maintained, we broadly suppressed the activity of parvalbumin-expressing (PV) inhibitory neurons and asked how this affected the balance of excitation and inhibition throughout auditory cortex. Activating archaerhodopsin in PV neurons effectively suppressed them in layer 4.

A guide to in vivo single-unit recording from optogenetically identified cortical inhibitory interneurons.

A major challenge in neurophysiology has been to characterize the response properties and function of the numerous inhibitory cell types in the cerebral cortex. We here share our strategy for obtaining stable, well-isolated single-unit recordings from identified inhibitory interneurons in the anesthetized mouse cortex using a method developed by Lima and colleagues. Recordings are performed in mice expressing Channelrhodopsin-2 (ChR2) in specific neuronal subpopulations.

Perceptual gap detection is mediated by gap termination responses in auditory cortex.

Background: Understanding speech in the presence of background noise often becomes increasingly difficult with age. These age-related speech processing deficits reflect impairments in temporal acuity. Gap detection is a model for temporal acuity in speech processing in which a gap inserted in white noise acts as a cue that attenuates subsequent startle responses.

Parvalbumin-expressing inhibitory interneurons in auditory cortex are well-tuned for frequency.

In the auditory cortex, synaptic inhibition is known to be involved in shaping receptive fields, enhancing temporal precision, and regulating gain. Cortical inhibition is provided by local GABAergic interneurons, which comprise 10-20% of the cortical population and can be separated into numerous subclasses. The morphological and physiological diversity of interneurons suggests that these different subclasses have unique roles in sound processing; however, these roles are yet unknown.