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Neuroscience Brown Bag Series

Thursday, October 05, 2017,
  • Location: Wilson Hall
  • Room: 316

Kaleb Lowe

Department of Psychology

Vanderbilt University

Stimulus-Response Mapping, Cue Congruency, and Cheating Monkeys

 

Cortical area frontal eye field (FEF) is intimately involved in the control of eye movements. Some FEF neurons respond to visual stimulation, some respond before eye movements, and some do both. In visual search, FEF neurons discriminate whether a search target is in or out of their receptive fields, but the heterogeneity of FEF responses raises a question: is the neural activity discriminating the location of the target related to the location of the target or the end of the saccade? In this talk, I will present a variant of a visual search task that incorporates an additional stimulus-response mapping stage that disentangles these two factors. The Schall Lab has previously used this task (Sato & Schall 2003), but here we expand it by introducing cue congruency manipulations. So far we have trained one subject on this task, with set sizes of 4 and 6 stimuli. On the surface he appears to have learned the task; with set size 4 he achieves ~80% accuracy on pro-saccade trials and ~50% accuracy on anti-saccade trials, both above chance level performance of 25%. However, analyses of cue-congruent, cue-incongruent, and cue-neutral task performance suggest that he may have adopted a sub-optimal strategy. Through behavioral results and patterns of errors, I will highlight the differences between this strategy and the intended strategy and begin a broader discussion regarding the difficulties of training non-verbal animals in cognitive tasks. Time permitting, I will end by presenting preliminary single-unit responses. The nature of these responses are indicative of the subject’s sub-optimal strategy, but still reveal important principles of the cortical control of eye movements.