title: Cortical delta activity reflects reward prediction error and related behavioral adjustments, but at different times.
abstract: Recent work has suggested that reward prediction errors elicit a positive voltage deflection in the scalp-recorded electroencephalogram (EEG); an event sometimes termed a reward positivity. However, a strong test of this proposed relationship remains to be defined. Other important questions remain unaddressed: such as the role of the reward positivity in predicting future behavioral adjustments that maximize reward. To answer these questions, a three-armed bandit task was used to investigate the role of positive prediction errors during trial-by-trial exploration and task-set based exploitation. The feedback-locked reward positivity was characterized by delta band activities, and these related EEG features scaled with the degree of a computationally derived positive prediction error. However, these phenomena were also dissociated: the computational model predicted exploitative action selection and related response time speeding whereas the feedback-locked EEG features did not. Compellingly, delta band dynamics time-locked to the subsequent bandit (the P3) successfully predicted these behaviors. These bandit-locked findings included an enhanced parietal to motor cortex delta phase lag that correlated with the degree of response time speeding, suggesting a mechanistic role for delta band activities in motivating action selection. This dissociation in feedback vs. bandit locked EEG signals is interpreted as a differentiation in hierarchically distinct types of prediction error, yielding novel predictions about these dissociable delta band phenomena during reinforcement learning and decision making.
authors: Department of Psychology, University of New Mexico, Logan Hall, 1 University of New Mexico, MSC03 2220, Albuquerque, NM 87131 USA. Electronic address: jcavanagh@unm.edu.
authors: James F
authors: JF
authors: Cavanagh
mesh_terms: D001519:Behavior / Q000502:physiology*; D002540:Cerebral Cortex / Q000502:physiology*; D003700:Delta Rhythm / Q000502:physiology*; D004569:Electroencephalography; D000066498:Emotional Adjustment / Q000502:physiology*; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology; D008297:Male; D015233:Models, Statistical; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012201:Reward; D055815:Young Adult
keywords: Decision making; Delta; Hierarchy; Prediction error; Reinforcement learning; Reward positivity