Neural Correlates of Human Associative Learning

Lesion studies in animals have associated the amygdala mainly with aversive conditioning, both cued and contextual. However, neurophysiological studies indicate that the amygdala has a role in the processing of positive emotions in some kinds of stimulus-reward learning. The aim of the current study was to extend these findings to humans. Functional magnetic resonance imaging was applied to investigate the neural basis of aversive and appetitive conditioning. In the first study, aversive electrical shocks were delivered as either cue or context related. The second study integrated appetitive and aversive conditioning using electric shocks as aversive and monetary rewards as appetitive reinforcers. Differential responses in the amygdala were observed during both cue and contextual conditioning, whereas context conditioning additionally recruited the hippocampus. Amygdala activity was higher for reinforced acoustic stimuli. The findings underline the importance of the amygdala in associative learning, irrespective of the stimulus valence and stimulus type.