Neural Circuits for Selective Auditory Filtering

To facilitate sensory processing in complex environments, the brain can selectively filter auditory input to enhance neural responses to relevant sounds and suppress responses to background distractors. Neural correlates of selective filtering have been observed in auditory cortex (AC), but the underlying neural circuitry has not yet been identified. A synthesis of existing results and our preliminary data suggests that selective auditory filtering arises through interactions between AC and two thalamic structures: the medial geniculate body (MGB), which sends direct excitatory input to AC and receives direct excitatory feedback from AC, and the thalamic reticular nucleus (TRN), which relays indirect inhibitory feedback from AC to MGB. In this proposal, we outline a plan to answer three key questions related to selective filtering: Q1: Are selective spectral and temporal filtering evident in the auditory thalamus? Q2: How do thalamocortical interactions contribute to spectral and temporal filtering? Q3: How does attention modulate spectral and temporal filtering? The proposed experiments will lead to significant advances in our knowledge of the general mechanisms that underlie active sensory processing in all mammals, while also helping build toward a detailed understanding of the neural circuitry that allows humans to understand speech in noisy environments.