Neurobiology and pharmacology of activational and effort-related aspects of motivation: rodent studies

Behavioral activation and exertion of effort are fundamental aspects of motivation. Exertion of effort enables organisms to overcome obstacles that separate them from significant stimuli. Moreover, organisms must frequently make effort-related decisions involving assessments of the relative benefits of available stimuli versus the costs of obtaining them. Effort-based decision making is studied using tasks that offer choices between high effort options leading to more highly valued reinforcers versus low effort/low reward options. These tasks have been used to study the involvement of neural systems, including mesolimbic dopamine and related circuits, in effort-related aspects of motivation. Recently, this research has led to the development of rodent pharmacological models of motivational symptoms that are seen in people with various psychiatric and neurological disorders.