GABAergic inhibition shapes the response properties of nearly every neuron in the auditory cortex, either directly (through synaptic inhibition onto th examined neuron) or indirectly (by inhibiting the excitatory cells that synapse onto it). This inhibition is generated by the roughly 20% of cortical neurons that are GABAergic. These neurons fall into multiple classes with distinct anatomical, chemical, and biophysical specializations, enabling intricate and precise modulation of cortical function. A full account of how the different types of inhibitory neurons shape cortical processing of sounds has yet to be generated, but will require A) that we understand the sensory or behavioral conditions in which each type is activated, and B) that we understand how their activation affects information processing in their direct targets and in the network overall. The goal of this proposal is to testin awake mice whether parvalbumin (PV) and somatostatin (SST) neurons, the two most numerous types of cortical inhibitory neuron, contribute differentially to auditory processing, in the context of two main questions about their function: 1) whether their effect is selective to non primary inputs or is similar across all parts of a neuron's receptive field, and 2) to what extent they mediate the effects of acoustic context on neural responses.
Both normal aging and mild hearing loss are associated with profound changes in processing of temporal and spectral context. The associated difficulties with speech comprehension lead to social isolation and significant decreases in quality of life. This work will allow us to relate low-level changes in intracortical inhibition to the high-level changes in perception and behavior observed in aging and disease, which will guide development of clinically useful manipulations to restore lost auditory processing capabilities.