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Suzanne P. McKee, Anthony M. Norcia; Dynamic topography of the response to monocular and binocular misalignment. Journal of Vision 2002;2(7):290. doi: 10.1167/2.7.290.
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© ARVO (1962-2015); The Authors (2016-present)
We mapped the global evoked response to monocularly- and binocularly-viewed contour misalignment, using a Geodesic Sensor Net equipped with 128 electrodes that completely blanketed the scalp. The monocular stimulus consisted of randomly-spaced vertical bars each containing multiple segments that were repetitively aligned and misaligned at a rate of 1 Hz. We paired the oscillating bars in one eye with static vertical bars in the other eye; the static bars were either straight or had large fixed offsets corresponding to the oscillating segments in the other eye. When fused binocularly, the observer saw rows of bar segments oscillating in depth interspersed with static segments. The Sensor Net measurements to the monocular oscillation showed a large response near the occipital pole, peaking at about 160 msec after the break in alignment. Over time, this monocular response spread to adjacent electrodes in front of and lateral to the occipital pole, so that by 250 msec after misalignment, activity was visible over two thirds of the scalp. When the monocular oscillating bars were paired with the static straight bars (creating a small disparity), the early occipital response was nearly identical to the monocular response. However, the late response in the lateral and frontal electrodes was greatly diminished. Binocular pairing with the offset static bars (creating a large disparity) virtually abolished the late response, leaving the early occipital response almost unchanged. While contour misalignment affects many cortical regions, the response to a disparate target is brief and confined to early visual areas. Movies of the development of the monocular and binocular responses will be shown.
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