Skilled interaction with objects in peripersonal space during visual navigation, object acquisition and manipulation (e.g., eating), and object avoidance is crucial in everyday life, not the least to avoid damage to the face and head. These abilities are impaired after parietal strokes that cause neglect. The goal of this investigation is to map the location and internal organization of parietal, temporal, and frontal cortical areas involved in combining visual and somatosensory information in peripersonal space. Studies in several areas in non-human primates including the ventral intraparietal area (VIP), area 7b, and the precentral polysensory zone (PZ) have shown that they contain multisensory neurons. In the case of VIP, neurons have aligned visual and somatosensory receptive fields on the face and upper body. VIP can be thought of as a parietal face area alongside the better known temporal lobe face areas involved in face recognition. The visual receptive fields of some VIP neurons shift relative to the retina in order to maintain responsiveness to the same part of visual space defined with respect to the head, suggesting that VIP uses a head-centered coordinate system. Neurons in VIP respond vigorously to optical flow stimuli like those produced by object movement and self-movement through complex environment (e.g., expansion).
Our first aim i s to retinotopically map the three multisensory areas. This extends our previous work mapping early and intermediate visual areas.
Our second aim i s to map the internal structure of the somatosensory responses in these areas using phase-encoded spatial air-puff stimuli on the face, neck, shoulders, and arms, to determine how stimuli from visual and somatosensory modalities interact, and to determine if the visual maps in human VIP, as well as 7b and PZ are head-centered.
The third aim i s to see whether these multisensory areas respond when subjects simply imagine navigating through familiar environments or imagine objects (e.g., a bee) approaching their face.
The fourth aim i s to determine to what extent these same areas automatically participate in cognitive tasks involving metaphorical ego or object movements in ordinary sentences such as, """"""""We are coming up on the holidays"""""""" or """"""""Thanksgiving is approaching"""""""".
The head contains the brain and key sense organs that must be protected in everyday encounters with objects, some of which need to be avoided and others of which need to be approached and sometimes eaten. These abilities are impaired in several different brain diseases.
This research aims to understand how visual and touch information is combined and processed during near-face encounters with moving objects.
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