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Selene Schintu, Michael Freedberg, Zaynah Alam, Eric Wassermann, Sarah Shomstein; Prismatic Adaptation Boosts Feedback-Based Learning. Journal of Vision 2017;17(10):1304. doi: 10.1167/17.10.1304.
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© ARVO (1962-2015); The Authors (2016-present)
Visuospatial cognition has an inherent spatial bias. Notably, the individual differences in the direction and magnitude of this bias are associated with the asymmetric pattern of binding of dopamine D2/3 receptors, as well as with dopamine system genes. Recent data also indicate that the hemispheric asymmetry of dopamine signaling is related to the propensity to learn from positive vs. negative feedback: High D2 receptor binding in the left hemisphere is associated with preference for rewarding events. Prismatic adaptation is a simple sensorimotor technique able to modulate visuospatial cognition according to the direction of the deviation. Left deviating prisms are hypothesized to induce a rightward bias in healthy subjects by inhibiting the posterior parietal cortex opposite to the prismatic deviation, via ipsilateral cerebellum, and releasing the contralateral hemisphere from interhemispheric inhibition. However, despite years of research, agreement on the exact mechanism of prismatic adaptation has not been reached. We hypothesize that left-deviating prism adaptation would decrease learning with negative feedback and increase learning with positive feedback. Healthy volunteers performed a two-choice feedback probabilistic classification task, which allows comparison of reward and punishment sensitivity, before and after adaptation to left prisms. On each trial, participants viewed one of four unrelated images, two belonging to a reward-learning condition and two to a punishment-learning condition, such that each category contained one rewarded and one punished stimulus. Correct trials yielded points in the reward condition, whereas incorrect trials decreased participants' score in the punishment condition. The rate of spontaneous blinking was recorded as an indirect measure of dopamine activity. Consistent with the hypothesis, preliminary results show an increase in learning rate only for positively reinforced items. These results suggest that prismatic adaptation acts asymmetrically on the dopamine system.
Meeting abstract presented at VSS 2017
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