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Philip Spinelli, Bingqing Wang, Tatiana Pasternak; Rapid loss of information about motion direction but not about its location during memory- guided comparison tasks. Journal of Vision 2013;13(9):368. doi: 10.1167/13.9.368.
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© ARVO (1962-2015); The Authors (2016-present)
In everyday perceptual experience stimulus features and their locations are largely inseparable. Indeed, during memory for motion tasks the information about location is preserved along with motion direction (Zaksas et al, 2001; Ong et al, 2009). Despite the documented link between processes underlying retention of features and their locations, little is known about the mechanisms underlying this link. We recently developed a behavioral paradigm that allows direct comparison between the ability to retain motion direction and its location. In the memory for direction task, subjects compare two moving stimuli, S1 and S2, separated by a memory delay and report whether they move in the same or in different directions. In the memory for location task, the two stimuli appear at the same or at different locations and subjects report whether the two locations are the same or different. In both tasks, the precision with which the information is retained is measured by varying the difference between S1 and S2. We trained a monkey on the two tasks and directly compared difference thresholds for direction and location. Both types of thresholds were measured with a 3[sup]o[/sup] moving random-dot stimuli (10[sup]o[/sup]/s) presented at the same eccentricity (7[sup]o[/sup]) over a range of delays separating S1 and S2 (0.75-3sec). The data revealed striking differences in the ability to retain the two types of information, with memory for location persisting with little or no deterioration and memory for direction decaying much more rapidly (tau=2.5s). These results suggest that the two types of information are likely to be mediated and maintained by different neuronal mechanisms, the notion supported by the difference in the nature of delay activity recorded in the prefrontal cortex during memory for location tasks (Funahashi et al, 1989) and during tasks requiring memory for motion (Hussar & Pasternak, 2012).
Meeting abstract presented at VSS 2013
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