A chief goal of sensory neuroscience is to understand how neural activity forms perception and guides behavior in awake, behaving subjects. A main component of sensory processing in awake animals involves the filtering of sensory information based upon behavioral context. The first goal of this proposal is to use neural recordings from the olfactory bulbs of awake, behaving mice to ascertain the degree of behavioral filtering present in the early stages of the olfactory system. The second goal is to examine the roles that feedback centrifugal projections from the cortex play in controlling this filtering. The second goal will be achieved using viral transduction of light-activated proteins to selectively block feedback from the olfactory (piriform) cortex during olfactory-based behaviors in mice. The olfactory system has been chosen for these studies based upon its clear ethological relevance for mice, as well as its well-defined corticofugal feedback from the piriform cortex to the olfactory bulb. Since these olfactory feedback projections resemble cortico-thalamic feedback seen in other sensory systems, our studies will be applicable to general mechanisms of sensory filtering across modalities, and will have particular relevance to disorders that impact sensory filtering, such as schizophrenia and autism spectrum disorders. PUBLIC HEALTH RELEVANCE: The studies within this proposal will investigate the role that behavioral context plays in sensory filtering, as well as possible neural mechanisms through which this filtering occurs. These studies will have applicability to psychiatric disorders that involve deficits in sensory filtering, such as schizophrenia and autism spectrum disorders.