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Stanley Komban, Jianzhong Jin, Yushi Wang, Reza Lashgari, Jens Kremkow, Jose-Manuel Alonso, Qasim Zaidi; Perceptual consequences of temporal differences in ON and OFF channels. Journal of Vision 2013;13(9):1022. doi: 10.1167/13.9.1022.
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© ARVO (1962-2015); The Authors (2016-present)
The time course of visual responses is thought to play a major role in visual processing. For example, X and Y thalamic cells in the cat (M and P cells in the primate) have different temporal properties and are presumed to serve different functions. In contrast to X and Y visual pathways, ON and OFF pathways were originally thought to differ only in contrast polarity. However, using multi-unit recordings from cortical neurons in layer 4 we found that response latency to dark is shorter than light stimuli. Besides latency difference, we also found that ON and OFF responses are biphasic in nature and that the rebounds are stronger in ON than OFF responses. To evaluate the perceptual consequence of a latency difference we presented two square targets as dark/light pairs on either sides of a central fixation spot. 3 observers were instructed to report the location of the target that appeared first and the proportion of correct responses were calculated for different inter-target onset delays. Observers showed consistent temporal advantage for dark targets when presented on a uniform noise background. To measure the effect of rebound on perception, we used a two interval forced choice paradigm to present two successive spatially overlapping targets of like polarity in a randomly chosen interval. 3 observers were asked to report the interval in which they saw a flicker. The inter-target interval to perceive a flicker at 75% threshold performance was significantly lower for dark targets than light targets consistent with the physiological finding. We thus demonstrate using psychophysics, the functional correlates of latency and rebound differences observed in the neural responses to increments and decrements.
Meeting abstract presented at VSS 2013
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