Population Coding of Species-Specific Vocalizations

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DESCRIPTION (provided by applicant): The ability of the auditory cortex to identify and extract relevant communication sounds in an acoustic environment that contains other irrelevant sounds is known as auditory scene analysis. This ability is important for any robust communication system that operates in a realistic environment. The goal of this application is to examine a possible mechanism by which auditory scene analysis is performed. This possible mechanism is the synchronous activity of neurons, which may facilitate the separation of vocalizations from other sounds. A large body of evidence indicates that synchronous neuronal activity is a general feature of cortical and thalamic networks. The functional role of this activity is still largely unknown, however. These findings have led to the hypothesis that synchronous activity reflects the grouping of distributed neuronal activities into a common representation of integrated stimulus features. This hypothesis predicts that synchronous interactions should occur between neurons located in multiple cortical areas. The objective of the proposed research is to expand our under-standing of synchronization in the auditory cortex. To achieve this goal, we will investigate the occurrence, proper ties, and stimulus dependence of temporal correlations of neuronal activity occurring simultaneously within and between auditory areas A1, R, and AL of marmoset auditory cortex. Simultaneous recordings will be made from each of the three auditory cortical areas while the marmoset vocally interacts with its peers in an unconstrained manner. This will permit an assessment of inter-areal synchrony, its temporal dynamics, and stimulus conditions under which it is expressed. A multichannel wireless system will be built to enable the process of recording and analyzing the activity of distributed groups of neurons in unrestrained animals. This will provide a powerful tool that will be used to trace neural pathways that process species-specific vocalizations. This will allow data to be recorded as animals naturally interact with each other, which is not possible with restrained animals. An additional benefit of the system is that is will provide a method of studying higher cortical areas where the optimal stimuli are not known a priori.