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Krasnow Institute > Monday Seminars > Abstracts How do we know when we move? -The role of Werner M. Graf Department of Physiology and Biophysics, Howard Medical School The posterior parietal cortex functions as an interface between sensory and motor cortices and is involved in the formation of motor plans and extrapersonal space representation. The ventral and medial intraparietal areas (VIP, MIP) receive significant vestibular input. Many neurons respond to horizontal rotation, and are strongly influenced by active head movement signals. Signal analysis suggests a putative role of this area in the discrimination of active and passive head movements. Retrograde transneuronal transfer of rabies virus was used to reveal the source of polysynaptic input to VIP/MIP after injection at sites of maximal vestibular responses. Conventional tracer results show that thalamic input to MIP/VIP is derived mainly from rostrodorsal portions of the pulvinar complex. These, in turn, are receiving input from the vestibular nuclei (VN) bilaterally, mainly contralaterally (in vestibulo-spinal and vestibulo-ocular domains), especially in the contralateral medial VN and the N. prepositus hypoglossi (putative source of eye position signals). In addition to vestibular cortex input, areas VIP/MIP receive input directly from vestibular end organs via ascending disynaptic pathways. Thus, VIP/MIP can be regarded as vestibular cortical areas and are thought to play a role in planning and processing of self-motion detection and eye-head-arm-hand movement control.
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