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Reppert, T.

Publications and source records attributed to Reppert, T..

2 recordsLinked to original sources

Neural Mechanisms for Executive Control of Speed-Accuracy Tradeoff

The balance of speed with accuracy requires error detection and performance adaptation. To date, neural concomitants of these processes have been investigated only with noninvasive measures. To provide the first neurophysiological description, macaque monkeys performed visual search under cued speed accuracy tradeoff (SAT). Monkeys changed SAT emphasis immediately after a cued switch while neuron discharges were sampled in medial frontal cortex area supplementary eye field (SEF). A multiplicity of SEF neurons signaled production of choice errors and timing errors. Modulation of SEF activity after choice errors predicted production of un-rewarded corrective saccades. Modulation of activity after timing errors signaled reward prediction error. Adaptation of performance during SAT of visual search was accomplished through pronounced changes in neural state from before search array presentation until after reward delivery. These results contextualize previous findings using noninvasive measures, complement neurophysiological findings in visuomotor structures, endorse the role of medial frontal cortex as a critic relative to the actor instantiated in visuomotor structures, and extend our understanding of the distributed neural mechanisms of SAT.\n\nHIGHLIGHTSO_LIMedial frontal cortex enables post-error adjustment during SAT\nC_LIO_LIChoice and timing errors were signaled by partially overlapping neural pools\nC_LIO_LIMedial frontal cortex can proactively modulate visuomotor processes\nC_LIO_LIMedial frontal cortex is to visuomotor circuits as critic to actor\nC_LI

neuroscience↗

Neural mechanisms of speed-accuracy tradeoff of visual search: Saccade vigor, targeting errors, superior colliculus and frontal eye field

Balancing the speed-accuracy tradeoff (SAT) is necessary for successful behavior. Using a visual search task with interleaved cues emphasizing speed or accuracy, we recently reported diverse contributions of frontal eye field (FEF) neurons instantiating salience evidence and response preparation. Here we report replication of visual search SAT performance in two macaque monkeys, new information about variation of saccade dynamics with SAT, extension of the neurophysiological investigation to describe processes in the superior colliculus, and description of the origin of search errors in this task. Saccade vigor varied idiosyncratically across SAT conditions and monkeys, but tended to decrease with response time. As observed in the FEF, speed-accuracy tradeoff was accomplished through several distinct adjustments in the superior colliculus. Visually-responsive neurons modulated baseline firing rate and the time course of salience evidence. Unlike FEF, the magnitude of visual responses in SC did not vary across SAT conditions, but the time to locate the target was longer in Accurate as compared to Fast trials. Also unlike FEF, the activity of SC movement neurons when saccades were initiated was equivalent in Fast and Accurate trials. Search errors occurred when visual salience neurons in FEF and SC treated distractors as targets, even in the Accurate condition. Saccade-related neural activity in SC but less FEF varied with saccade peak velocity. These results extend our understanding of the cortical and subcortical contributions to SAT.\n\nSignificance statementNeurophysiological mechanisms of speed-accuracy tradeoff (SAT) have only recently been investigated. This paper reports the first replication of SAT performance in nonhuman primates, the first report of variation of saccade dynamics with SAT, the first description of superior colliculus contributions to SAT, and the first description of the origin of errors during SAT. These results inform and constrain new models of distributed decision-making.

neuroscience↗