Individual differences in relative left frontal cortical activity and willingness to expend effort for reward

Selective impairment of reward motivation is a feature of several psychiatric disorders, particularly depression. Individual differences in reward motivation also exist in the healthy population and indices of such differences may serve as pre-clinical markers for those at risk of developing psychopathology. Greater left, relative to right, frontal cortical asymmetry (LFA) in the alpha band of an electroencephalogram is one such marker, however, little work has sought to link LFA with behavioural indices of approach motivation. The present study examines LFA in relation to a behavioural measure of approach motivation, the Effort Expenditure for Rewards Task (EEfRT; Treadway, Buckholtz, Schwartzman, Lambert, & Zald, 2009). Nineteen participants (55% female) completed the EEfRT – a cost-benefit decision-making task, in which participants must decide between high-effort, high-reward, and low-effort, low-reward tasks, under varying levels of likelihood of reward delivery - and subsequently underwent an EEG recording, from which LFA was calculated using power spectral analysis. Psychometric measures of reward responsivity were also completed. Analyses suggested the existence of a moderate, though non-significant relationship between individual differences in LFA and willingness to expend effort for reward on the EEfRT, such that greater resting LFA was associated with greater willingness to pursue larger rewards, especially under conditions of uncertain reward delivery. Implications of the results are discussed in relation to issues of heterogeneity in measurement and classification of trait markers and processes mitigating cost-benefit decision-making in the pursuit of rewards. Copyright © 2015 Published by Elsevier Ltd.