Effects of motivation on behavior and brain activity during performance of a cognitive control task

 

Hannah S. Locke and Todd S. Braver
Psychology Department, Washington University, St. Louis, MO USA

 

Does motivation impact cognition by modulating activity in brain regions sensitive to reward and penalty, through direct task-processing pathways, or through higher-level cognitive control structures? The current study addressed this question by providing motivational incentives (performance-dependent monetary rewards and penalties) while participants engaged in a highly decomposable cognitive control task: a Go/No-Go variant of the AX-CPT. Sixteen participants underwent fMRI scans while performing the task under three blocked conditions: baseline, reward-motivated, and penalty-motivated. The reward-motivated condition provided monetary bonuses for fast and correct responses on Go trials, the penalty-motivated condition subtracted money for errors committed on No-Go trials, and the baseline condition had no monetary incentives. A mixed state-item design enabled extraction of both sustained and transient neural activity associated with motivation condition. Behavioral data showed that these conditions were effective at adjusting performance, with reward significantly decreasing overall RT, and penalty resulting in fewer No-Go errors. Neuroimaging data indicated that the reward-motivated condition was associated with a sustained increase in activity in a wide-spread network that included right lateral PFC. Additionally, reward-motivation led to transient increases in activity for all trial types within medial occipitoparietal cortex and the basal ganglia. Activity in these latter regions was directly linked with trial performance, such that faster responses (i.e., increased reward likelihood) were associated with greater activation. These results suggest that motivational incentives may modulate processing and performance through a distributed set of neural mechanisms, including sustained attention (right PFC), cue-based reward expectation (basal ganglia) and transient visual discrimination (occipitoparietal cortex).