| Abstract No.: | B-D2132 |
| Country: | Canada |
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| Title: | EYE POSITION MODULATION OF A TACTILE STIMULUS WITHIN POSTERIOR PARIETAL CORTEX USING FMRI |
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| Authors/Affiliations: | 3 Khalid Tahir*; 1 Aidan Thompson; 1 Teser Wong Wong; 4 Shima Ovaysikia; 2 Joseph DeSouza; 1 Denise Henriques;
1 Center for Vision Research, Kinesiology and Health Science, York University; 2 Psych Dept, Center for Vision Research, York University; 3 Psych Dept, York University; 4 Pysch Dept, Center for Vision Research, York University, Toronto, ON, Canada
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| Content: | Objective: The representation of a spatially constant world in the face of ever-changing stimuli on the retina is a curious phenomenon. One of the ways consistency can be achieved is through cortical remapping of the environment. The posterior parietal cortex (PPC) has been a focus of study, and has been found to be responsible for remapping visual stimuli.
Materials and Methods: We use functional magnetic resonance imaging to find modulation of activity by eye position in the PPC with a tactile stimulus in eight subjects. Two alternating puffs of air were applied to the back of the right hand as it rests on the midline at a rate of 2Hz, while subjects fixate to the right or left of midline for 8 seconds at a time. Results: Air puffs of the right hand result in activation of the left post central gyrus in the primary somatosensory cortex. An ipsilateral effect is observed in the right cortical hemisphere; a volume of interest (VOI) analysis showed a greater number of voxels are active in the right PPC for puffing on the hand with gaze to the right than puffing on the hand while gazing left.
Conclusion: This study shows that the PPC codes tactile stimuli in a similar manner as visual stimuli relative to gaze, and that this activity is modulated across the midline of the body as a function of gaze direction.
Funded by NSERC to JFXD, CIHR to DYPH, CIHR Training Grant in Vision Health Research to AAT
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