Event-related Fmri of Reward Related Brain Activity in Children and Adolescents

Abstract:
Reward related neural systems have been implicated in the pathology of mood disorders. Single cell recordings in non-human primates have identified areas with increased dopaminergic neural activity as a function of reward. Recent studies using event-related functional Magnetic Resonance Imaging (fMRI) in adults have concurred by identifying increased blood flow to the caudate, ventral striatum, and orbitofrontal cortex during reward paradigms. The goals of the current study are to further characterize reward related activity using fMRI and investigate children and adolescents in a study that examines risk factors for anxiety and depression. Participants were 15 subjects aged 9-16 years that played a guessing game in which correct responses earned a monetary reward. Regions and time-courses of reward related activity were similar to that found in adults with strong activity in the caudate that was differentially sustained for rewarding trials versus punishing trials. An analysis to examine reward expectancy revealed greater sustained activity in the ventral striatum and orbitofrontal cortex when expectation was high versus low. These results support event-related fMRI as a tool for understanding reward systems and establish the plausibility of using fMRI in children. We will also inspect preliminary data from a sample of children and adolescents who are currently, or at risk of becoming, depressed.