Characterization of reward and effort mechanisms in apathy

Publication date: Available online 18 April 2014 Source:Journal of Physiology-Paris Author(s): Valerie Bonnelle , Kai-Riin Veromann , Stephanie Burnett Heyes , Elena Lo Sterzo , Sanjay Manohar , Masud Husain Apathy is a common but poorly understood condition with a wide societal impact observed in several brain disorders as well as, to some extent, in the normal population. Hence the need for better characterization of the underlying mechanisms. The processes by which individuals decide to attribute physical effort to obtain rewards might be particularly relevant to relate to apathy traits. Here, we designed two paradigms to assess individual differences in physical effort production and effort-based decision-making and their relation to apathy in healthy people. Apathy scores were measured using a modified version of the Lille Apathy Rating Scale, suitable for use in a non-clinical population. In the first study, apathy scores were correlated with the degree to which stake (reward on offer) and difficulty level impacts on physical effort production. Individuals with relatively high apathy traits showed an increased modulation of effort while more motivated individuals generally exerted greater force across different levels of stake. To clarify the underlying mechanisms for this behavior, we designed a second task that allows independent titration of stake and effort levels for which subjects are willing to engage in an effortful response to obtain a reward. Our res...

Source: Journal of Physiology Paris - October 12, 2014 Category: Physiology Source Type: research