| Abstract No.: | C-D3133 |
| Country: | Canada |
| | |
| Title: | IS THERE AN EYE POSITION SIGNAL IN THE HUMAN SOMATOSENSORY CORTEX USING FMRI? |
| | |
| Authors/Affiliations: | 4 Khalid Tahir*; 1 Shima Ovaysikia; 2 Denise Henriques; 3 Joseph DeSouza;
1 Center for Vision Research, York University, Toronto, ON, Canada; 2 Kinesiology and Health Science, Center for Vision Research, York University; 3 Psych Dept, Center for Vision Research, York University, Toronto, ON, Canada; 4 Psych Dept, York University, Toronto, ON, Canada
|
| | |
| Content: | Objective: It is commonly assumed that saccade generation does not rely on proprioception, or muscle feedback. However, a proprioceptive eye position signal (Wang et al, 2007) and mid-flight compensation of perturbed saccades have been found in monkey (Goossens & Van Opstal, 2000). Wang and colleagues (2007) found that in the monkey the representation of eye position was near cells with a tactile representation of the contralateral brow. This area of the primate somatosensory cortex was indeed small, a 4mm by 4mm space within the recording chamber. Thus, an active mechanism for saccade control requires neural input in the form of feedback from the eye muscles to the brain, however to our knowledge, such an eye position signal has not been found in human somatosensory cortex. We attempted to activate this somatosensory representation of the area around the eyes by having subjects make a blinking movement.
Materials and Methods: Using functional magnetic resonance imaging (fMRI), we sought to find a somatosensory component of a blinking signal with a blocked design. Subjects completed 8-s blocks of visually evoked voluntary blinks at a rate of 1Hz while looking to the left or right of midline, alternated with 8-s fixation control blocks. Results: We mapped the somatosensory cortex of subjects, and a blinking signal is found in the post central gyrus in 4 of 8 subjects. During blinking trials, other active areas include the inferior parietal lobule (BA 40), cingulate gyrus (BA 24), and cuneus (BA 18). Preliminary findings in 1 of 4 subjects show an eye position signal.
Conclusion: The signal in somatosensory cortex may show that humans have access to an eye position signal, a necessary component of an active mechanism, and has significant implications in understanding the mechanisms for making eye movements.
Funded by NSERC to JFXD, CIHR to DYPH |
| | |
| Back |
|
