Lateralized readiness potentials reveal properties of a neural mechanism for implementing a decision threshold

Abstract

Many perceptual decision making models posit that participants accumulate noisy evidence over time to improve the accuracy of their decisions, and that in free response tasks, participants respond when the accumulated evidence reaches a decision threshold. Research on the neural correlates of these models' components focuses primarily on evidence accumulation. Far less attention has been paid to the neural correlates of decision thresholds, reflecting the final commitment to a decision. Inspired by a model of bistable neural activity that implements a decision threshold, we reinterpret human lateralized readiness potentials (LRPs) as reflecting the crossing of a decision threshold. Interestingly, this threshold crossing preserves signatures of a drift-diffusion process of evidence accumulation that feeds in to the threshold mechanism. We show that, as our model predicts, LRP amplitudes and growth rates recorded while participants performed a motion discrimination task correlate with individual differences in behaviorally-estimated prior beliefs, decision thresholds and evidence accumulation rates. As such LRPs provide a useful measure to test dynamical models of both evidence accumulation and decision commitment processes non-invasively.

Publisher

Public Library of Science

Publication Date

1-1-2014

Publication Title

PLoS ONE

Department

Neuroscience

Document Type

Article

DOI

https://dx.doi.org/10.1371/journal.pone.0090943

Keywords

Reaction-time tasks, Dorsolateral prefrontal cortex, Perceptual decision, Electrophysiological evidence, Prior probability, Diffusion-model, Choice tasks, Human brain, Reward rate

Language

English

Format

text

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