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Neuroscience Brown Bag Series

Thursday, October 11, 2018,

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  • Location: Wilson Hall • 111 21St Ave S • Nashville, TN 37240
  • Room: 316

Thomas Reppert, PhD & Jeffrey Schall, PhD with data from Richard P. Heitz

Department of Psychology

Vanderbilt University

"Proactive control and performance monitoring of speed-accuracy tradeoff by supplementary eye field"

Classic analysis of the speed-accuracy tradeoff pits speed against accuracy. Importantly, the notion of accuracy is typically one of choice accuracy or movement accuracy (e.g., endpoint error relative to stimulus). While these errors in decision accuracy are prevalent, so too are errors in decision timing. As speed constraints are strengthened, the likelihood of a mis-timed response increases. We applied response timing constraints on macaque monkeys as they performed a visual search task for a shape singleton amongst distractors. The monkeys naturally preferred quick responding, accepting more choice inaccuracies for greater rate of responding. When slow responding was imposed by task constraints, rate of choice errors decreased, but rate of timing errors increased. That is, the monkeys’ propensity for quick responding was evident as rate of response timing errors rose markedly with change in task cue constraints. We recorded from SEF neurons while the monkeys performed speed-accuracy tradeoff of a visual search task. We found that SEF baseline activity was equivalent across Fast and Accurate conditions and was a strong predictor of response time. Visual response magnitude, but not latency, varied across Fast and Accurate conditions. The changes in visual response magnitude were evident within a single trial after a task condition switch, from Fast to Accurate or vice versa. On Fast trials, SEF neurons signaled response choice errors after the erred response; on Accurate trials, neurons signaled negative reward prediction error at the time of expected reward. These results suggest that medial pre-frontal cortex plays a pivotal role in proactive control and performance monitoring of speed-accuracy tradeoff.