Worth the ‘EEfRT’? The Effort Expenditure for Rewards Task as an Objective Measure of Motivation and Anhedonia

Background: Of the putative psychopathological endophenotypes in major depressive disorder (MDD), the anhedonic subtype is particularly well supported. Anhedonia is generally assumed to reflect aberrant motivation and reward responsivity. However, research has been limited by a lack of objective measures of reward motivation. We present the Effort-Expenditure for Rewards Task (EEfRT or ‘‘effort’’), a novel behavioral paradigm as a means of exploring effort-based decision-making in humans. Using the EEfRT, we test the hypothesis that effort-based decision-making is related to trait anhedonia. Methods/Results: 61 undergraduate students participated in the experiment. Subjects completed self-report measures of mood and trait anhedonia, and completed the EEfRT. Across multiple analyses, we found a significant inverse relationship between anhedonia and willingness to expend effort for rewards. Conclusions: These findings suggest that anhedonia is specifically associated with decreased motivation for rewards, and provide initial validation for the EEfRT as a laboratory-based behavioral measure of reward motivation and effort-base

Early processing of emotional faces in a Go/NoGo task: lack of N170 right-hemispheric specialisation in children with major depression

Emotionally biased information processing towards sad and away from happy information characterises individuals with major depression. To learn more about the nature of these dysfunctional modulations, developmental and neural aspects of emotional face processing have to be considered. By combining measures of performance (attention control, inhibition) in an emotional Go/NoGo task with an event-related potential (ERP) of early face processing (N170), we obtained a multifaceted picture of emotional face processing in a sample of children and adolescents (11-14 years) with major depression (MDD, n = 26) and healthy controls (CTRL, n = 26). Subjects had to respond to emotional faces (fearful, happy or sad) and withhold their response to calm faces or vice versa. Children of the MDD group displayed shorter N170 latencies than children of the CTRL group. Typical right lateralisation of the N170 was observed for all faces in the CTRL but not for happy and calm faces in the MDD group. However, the MDD group did not differ in their behavioural reaction to emotional faces, and effects of interference by emotional information on the reaction to calm faces in this group were notably mild. Although we could not find a typical pattern of emotional bias, the results suggest that alterations in face processing of children with major depression can be seen at early stages of face perception indexed by the N170. The findings call for longitudinal examinations considering effects of development in children with major depression as well as associations to later stages of processing