Experience-dependent changes in human brain activation during contingency learning

Successful adaption requires learning to respond appropriately to cues associated with response-reinforcer contingencies. In this investigation, we used functional magnetic resonance imaging to characterize changes in frontal and limbic activation associated with learning under a positive reinforcement contingency. Imaging analyses identified linear and nonlinear changes in brain activation across nine reinforcement trials when response accuracy and reaction times were stable. The development of contingency control was generally associated with linear increases or inverted-U shaped changes in activation in superior, medial and orbitofrontal (OFC) regions, amygdala, insula and the medial temporal lobe. Linear decreases and U-shaped changes in activation were generally observed in parietal, occipital and cerebellar regions. Results highlighting linear increases in activation in superior, medial and OFC regions suggest involvement in the development of contingency control, even when behavior is stable. Results also highlighted a positive correlation between changes in OFC activation and amygdala activation. However, inspection of the correspondence between group changes and individual subject changes in OFC, amygdala and insula activation revealed that approximately half of subjects exhibited changes resembling group changes and the strength of the OFC-amygdala relationship varied markedly between subjects. Such disparities highlight a unique opportunity for exploring individual differences in regional sensitivity to contingency as well as improving experimental preparations to better highlight and control the effects of extraneous variables.