The neural circuits underlying normal spatial vision and attentive sensorimotor behavior of primates have been most intensively studied in macaque monkeys. Both electrophysiological and anatomical studies have highlighted the importance of the posterior parietal cortex for the integration of neural signals from different sensory modalities and its use for guiding and controlling action in space. In the monkey, a highly modular structural and functional specialization has been demonstrated within this part of the brain. One such functionally specialized area is the ventral intraparietal area (VIP) located in the fundus of the intraparietal sulcus (IPS). I will review a number of recent studies where we have shown that area VIP contains many neurons that show multisensory directionally selective discharges, i.e. these neurons respond to moving visual, tactile, vestibular or auditory stimuli. The functional properties imply that area VIP is involved in the encoding of self- and/or object motion in near-extrapersonal space. In addition, many VIP neurons also encode sensory information from different modalities in a common, probably head-centered, frame of reference. Although many specific human behaviors necessitate the convergence and integration of information conveyed through anatomically distinct sensory pathways, to date little is known about polymodal motion processing and integration in humans. To test for equivalencies between macaques and humans, we used functional MRI in normal human subjects while presenting moving visual, tactile, or auditory stimuli. Our functional imaging data reveal a network of cortical areas that respond to multisensory stimuli conveying motion information. One of these regions of activation is located in the depth of human IPS. Accordingly, we suggest that this area constitutes the human equivalent of monkey area VIP.
University of Manchester (2010) Proc Physiol Soc 19, SA69
Research Symposium: Multisensory navigation in primates
F. Bremmer1
1. Dept. Neurophysics, Philipps-University Marburg, Marburg, Germany.
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Where applicable, experiments conform with Society ethical requirements.