title: Withholding a Reward-driven Action: Studies of the Rise and Fall of Motor Activation and the Effect of Cognitive Depletion.
abstract: Controlling an inappropriate response tendency in the face of a reward-predicting stimulus likely depends on the strength of the reward-driven activation, the strength of a putative top-down control process, and their relative timing. We developed a rewarded go/no-go paradigm to investigate such dynamics. Participants made rapid responses (on go trials) to high versus low reward-predicting stimuli and sometimes had to withhold responding (on no-go trials) in the face of the same stimuli. Behaviorally, for high versus low reward stimuli, responses were faster on go trials, and there were more errors of commission on no-go trials. We used single-pulse TMS to map out the corticospinal excitability dynamics, especially on no-go trials where control is needed. For successful no-go trials, there was an early rise in motor activation that was then sharply reduced beneath baseline. This activation-reduction pattern was more pronounced for high- versus low-reward trials and in individuals with greater motivational drive for reward. A follow-on experiment showed that, when participants were fatigued by an effortful task, they made more errors on no-go trials for high versus low reward stimuli. Together, these studies show that, when a response is inappropriate, reward-predicting stimuli induce early motor activation, followed by a top-down effortful control process (which we interpret as response suppression) that depends on the strength of the preceding activation. Our findings provide novel information about the activation-suppression dynamics during control over reward-driven actions, and they illustrate how fatigue or depletion leads to control failures in the face of reward.
authors.affiliation: University of California, San Diego.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Freeman
authors.affiliation: University of California, San Diego.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Aron
mesh_terms: D001921:Brain / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D004576:Electromyography; D019054:Evoked Potentials, Motor; D005260:Female; D006225:Hand / Q000502:physiology; D006801:Humans; D007175:Impulsive Behavior / Q000502:physiology; D007266:Inhibition, Psychological; D008297:Male; D009042:Motivation / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology*; D011930:Reaction Time; D012201:Reward; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult