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David Arnoldussen, Jeroen Goossens, AV van den Berg; Where two eyes are better than one for processing heading. Journal of Vision 2012;12(9):751. doi: 10.1167/12.9.751.
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© ARVO (1962-2015); The Authors (2016-present)
Optic flow contributes importantly to visual navigation and perception of depth relations. So much so, that stereoscopic processing is often ignored in optic flow research although the natural stimulus consists of stereoscopic flow. Here we ask which parts of human visual cortex respond differently to monocular and binocular flow-signals. We investigated BOLD responses while subjects were exposed to wide-field (120x90 deg) presentation of the stimulus. Scanning was performed on a Siemens 3T (resolution 2.0 mm isovoxel, 32 slices, TR: 2000 ms, TE: 28 ms). To distinguish contributions of binocular summation and stereoscopic processing we presented in addition to monocular and stereoscopic also a 'synoptic' condition, in which both eyes were stimulated with identical patterns of flow on the retinae. We simulated forward motion (.25 m/s) through a 3D cloud (depth: 5m) of 300 points (150 dark and 150 light) on a grey background. To compare responses to self-motion patterns and to speed-matched incoherently moving dots, we rotated each motion vector by a random angle in the image plane (angular range dA: 0, 30, or 60 deg; lifetime: 1 s). We found clear differences between monocular and binocular conditions in several optic flow responsive areas: V3A, V6, MT+, VIP, and p2v. We found a large response increment to turbulent stereo flow in all motion-responsive areas and a specific response increment to forward motion (dA = 0) in p2v and VIP. These findings point to a widespread interaction between stereo information and local-motion in human cortex and a specific interaction of self-motion stimuli and stereo information in higher motion-areas p2v and VIP.
Meeting abstract presented at VSS 2012
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