Spectro-temporal Plasticity in Primary Auditory Cortex

University Of Maryland College Pk Campus, College Park MD

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Abstract

DESCRIPTION (provided by applicant): It is well established that auditory experience can cause significant and continuous reorganization and receptive field plasticity in the primary auditory cortex (AI). The exact form of this plasticity depends on the details of the behavioral context, and of the spectral and temporal cues in the acoustic stimuli. Recent findings indicate further that neuronal responses in AI of awake behaving animals reflect motor, attention, and reward dimensions, rather than simply encoding the acoustic features of the stimuli. This is consistent with findings in other neural systems and supports the hypothesis that auditory cortical cells may undergo rapid, short-term, and context-dependent changes of their receptive field properties when an animal is engaged in different auditory behavioral tasks. This kind of plasticity would likely involve a selective functional reconfiguring of the underlying cortical circuitry to sculpt the most effective receptive field for accomplishing the auditory task. The proposed research explores this hypothesis in combined physiological/behavioral experiments in which spectroternporal receptive fields (STRFs) will be rapidly and comprehensively characterized simultaneous with the animal behavior. The experiments also contrast STRF plasticity in a single cell across different auditory tasks employing various acoustic signals with controlled spectral and temporal features. These unique capabilities are made possible by the development of new ripple stimuli to engage the animal behaviorally while rapidly measuring its cortical STRFs, and versatile response indicators that are sensitive barometers of how behavior affects a cell's responsiveness. The overall goal of the proposed study is to test whether it is possible, under the same reference-target discrimination paradigm, to induce rapid STRF plasticity along specific temporal or spectral dimensions by choosing the appropriate cues in the acoustic target. All experiments follow the same behavioral procedure in which reference signals are broadband, temporally and spectrally rich stimuli that also serve during physiological experiments to characterize the STRF of the cell under study. By contrast, the target provides the discrimination signal. It varies from one experiment to the other with distinctive features that can be (AIM I) purely temporal, (AIM II) purely spectral, or (AIM III) combined spectrotemporal.