Neuroscience 2005 Abstract
| Presentation Number: | 619.18 |
|---|---|
| Abstract Title: | Spatially asymmetric fMRI response to moving patterns: perceptual correlate reveals a trailing-edge-specific process. |
| Authors: |
Whitney, D.*1,2
; Goltz, H. C.1
; Bressler, D.3
1Center for Mind & Brain, Univ. of California, Davis, CA 2Department of Psychology, Univ. of California, Davis, CA 3ON, 202 Cousteau Pl, Suite 201, 95616, |
| Primary Theme and Topics |
Sensory and Motor Systems - Vision -- Processing of visual motion |
| Secondary Theme and Topics | Cognition and Behavior<br />- Human Cognition, Behavior, and Anatomy<br />-- Perception and imagery |
| Session: |
619. Motion Processing III Poster |
| Presentation Time: | Tuesday, November 15, 2005 9:00 AM-10:00 AM |
| Location: | Washington Convention Center - Hall A-C, Board # Q3 |
| Keywords: | Visual Perception, Visual Motion, Visual Cortex, FMRI |
A number of recent studies have shown that early visual areas have a spatially asymmetric response to visual motion: there is a stronger fMRI response at the origin of motion or trailing edge of a moving pattern (Whitney, et al., Science, 2003; Koyama, et al., SfN, 2003). Some studies reported that the effect is significant but small (Liu, et al., SfN, 2004; Ashida & Smith, VSS, 2005); the increased response at the trailing edge of the moving pattern corresponds to a 1-2 mm shift in the location of that edge. However, the size and nature of the effect is difficult to interpret since no experiment has systematically examined how the spatially inhomogeneous response correlates to perception. To address this question, we used a spatial correlation technique (similar to Haxby, et al., 2001), which provides a more precise estimate of the perceptual correlate of this activity. We presented Gabor patterns (with stationary envelopes) containing a carrier that could drift toward or away from the fovea. In separate localizer runs, we presented the same Gabors in counterphase flicker (no net motion) at five different eccentricities. The variation in the spatial correlation of responses to the localizer Gabors allowed us to resolve Gabors that were physically separated by less than 1 degree of visual angle. More importantly, we spatially correlated the flickering Gabors that were physically displaced with those containing a drifting carrier and found that the response to the drifting Gabors was equivalent to a shift in the centroid and a skew in the contrast of the Gabor’s gaussian envelope. This is consistent with a directionally selective deblurring mechanism that operates specifically at the trailing edges of moving patterns (Burr, et al., 1986; Whitney, et al., 2003).
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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