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Martin Szinte, Mark Wexler, Patrick Cavanagh; Temporal dynamics of remapping captured by peri-saccadic motion trace. Journal of Vision 2010;10(7):158. doi: 10.1167/10.7.158.
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© ARVO (1962-2015); The Authors (2016-present)
Whenever an eye movement is made, several visual areas (e.g., LIP, FEF, CS) help maintain visual stability by shifting the activation for currently attended targets to the locations these targets will have after a saccade. The temporal dynamics of this anticipatory activation, known as remapping, can be visualized with a continuous motion stimulus that begins before and ends after the saccade. We asked participants to make horizontal saccades following the fixation point as it jumped 15 deg to the left or to the right. A red square moved vertically at 50 deg/sec covering 25 deg midway between the first and second fixation point locations. The motion began 50 msec before the fixation point shifted and about 200 msec before the saccade onset. Even though the motion of the red square was vertical, participants reported that it appeared separated in two pieces, with the second part being displaced in the direction of the saccade. Using this procedure, we first evaluate the amount of displacement of the second part of the motion trace compared to the first part. Then we used this amount to null the effect and find the moment at which this error of remapping occurred. The magnitude of the trace offset around the time of the saccade was about 15-20% of the saccade amplitude, and this offset appeared in a temporal window about 30 msec to 70 msec after the saccade onset. The displacement of the pre-saccadic relative to post-saccadic motion trace suggests that the remapping overcompensates for the saccade vector. Moreover, the visibility of the pre-saccadic trace after the saccade is a novel demonstration of spatiotopic visual persistence; visual because monitor persistence would not show a break between the pre- and post-saccadic portions of the trace
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