Somatosensory Cortical Influences on Subcortical Processing

The basal ganglia and pontocerebellar systems are both involved in sensorimotor and cognitive behaviors. While it is often difficult to activate cognitive processes in animals in a controlled manner, the somatosensory system and its targets are easily activated by controlled stimulation. Hence, the structural and functional principles that govern sensory integration in these brain regions are likely to apply to the integration of cognitive information as well. Using the somatosensory system as a model system, we plan to analyze and compare the integration of cortical inputs in both the neostriatum and the pons. The potential clinical importance of this work is underscored by the fact that the basal ganglia have been implicated in several neurologic disorders including Parkinson's disease, Huntington's chorea, and Tourette's syndrome, while the pontocerebellar system is associated with several clinical sensorimotor problems. This project has four aims: Aim 1. Support or refute the hypothesis that bilateral corticostriatal and corticopontine overlap is greatest for projections from Ml sites representing proximal body parts that are bilaterally coordinated. Aim 2. Support or refute the hypothesis that corticopontine projections from SI and SI I enable more integration than corticostriatal projections from the same sites or than projections from SI and ML Aim 3. Support or refute the hypothesis that neostriatal neurons discharge mainly when they receive synchronous inputs from related (ie., interconnected) cortical areas in somatosensory cortex. Aim 4. Support or refute the hypothesis that stimulus-induced neuronal activity in SI barrel cortex and the pons are more strongly correlated than stimulus-induced activity in SI cortex and the neostriatum.