The neostriatum and related parts of the basal ganglia contain functional channels that separately process prefrontal, limbic, oculomotor, and sensorimotor information received from the cerebral cortex. Although the specific cortical areas that activate each functional channel are different, each channel contains the same basic input-output pattern of connections. By using cutaneous stimuli to activate corticostriatal projections from somatosensory cortex, we can characterize the pattern recognition properties of neostriatal neurons and determine how neural activity in the sensorimotor channel is coordinated during sensory stimulation. Hence, this paradigm presents a unique opportunity for understanding the rules that govern the dynamic operation of corticostriatal circuits across all functional channels because there are no accepted methods for directly activating limbic or prefrontal channels in a controlled, naturalistic manner. The anatomic and physiologic properties of the neostriatum represent a significant issue in contemporary neuroscience because this brain region has been implicated in Parkinson's disease, Huntington's chorea, Tourette's syndrome, and schizophrenia. In this project we will use anterograde tracing methods to test the hypothesis that corresponding representations in the primary and secondary somatosensory cortical areas send convergent projections to the neostriatum. We will also use retrograde tracing techniques to verify previous results indicating that corticostriatal projections from somatosensory cortex have an anisostropic organization. We will also compare corticostriatal and corticopontine projections to determine if the corticopontine projections follow the same principles of organization that have been identified in the corticostriatal system (ie. Principles of Cortical Proximity, Somatotopic Homology, and Behavioral Cooperativity). Finally, we will record neuronal activity in multiple parts of the cerebral cortex and neostriatum so that we may analyze neuronal interactions between the cortex and neostriatum. These physiology studies will determine whether a primary function of neostriatal neurons is to detect synchronized activity among functionally-related cortical areas.
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