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Daniel Tso, Ronald Miller, Momotaz Begum; Neuronal responses underlying shifts in interocular balance induced by short-term deprivation in adult macaque visual cortex. Journal of Vision 2017;17(10):576. doi: 10.1167/17.10.576.
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Psychophysical studies and functional optical imaging experiments in V1 have shown that short-term monocular deprivation (STMD, depriving one eye for 1-3 hours, either total occlusion or pattern deprivation) disrupts interocular balance. In such studies, the relative contribution of the deprived eye was surprisingly elevated for more than an hour after deprivation. We have now conducted multi-electrode recordings in macaque V1 before, during and after STMD. The single-unit recordings revealed several different types of cell responses. Of a sample of 32 neurons, 40% exhibited increased relative strength of the deprived eye input after STMD, 28% strongly so (MD index > 0.25) whereas only 6% exhibited a strong relative shift favoring the non-deprived eye (MDI < -0.25). The strongest MDI increases were observed in cells where its non-dominant eye was deprived. The relative strengthening of the deprived eye was due to either a strengthening of the response to the deprived eye, or a weakening of the non-deprived eye, or both. Our previous STMD optical imaging uncovered a marked weakening of the non-deprived eye during the deprivation period that only reversed with the ending of the deprivation of the other eye. Similarly, 66% of the recorded cell sample also exhibited a marked weakening of responses to the non-deprived eye during the deprivation period. It cannot be explained by adaptation or fatigue in the eye or cortex since the weakening reverses with the ending of deprivation of the other eye. A minority (16%) of cells demonstrated responses more consistent with the classical relative weakening of the deprived eye. Overall, the results show V1 cell response behaviors that likely constitute components of the shifts in interocular balance induced by STMD observed in the imaging studies and psychophysically. The findings suggest a dynamic binocular mechanism for regulating interocular balance that involves the neurons in V1.
Meeting abstract presented at VSS 2017
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