Dopamine transmission in the amygdala modulates surprise in an aversive blocking paradigm.

Learning about predictive relationships depends on surprise. For example, in Kamin's blocking paradigm learning about the association between one stimulus (X) and a footshock is attenuated when X→footshock training occurs in the presence of a good predictor (A) of that footshock. Establishing the neural processes that underlie this effect has generated considerable interest in recent years. Here, an infusion of the dopamine antagonist cis-(z)-Flupenthixol into the amygdala prior to compound (AX) conditioning attenuated the blocking effect, but had no effect on controls. This effect of dopamine antagonism in the amygdala immediately prior to compound conditioning was obtained irrespective of whether infusions occurred prior to the first, second or both compound conditioning trials. These results provide evidence for the involvement of amygdaloid dopamine in regulating surprise in fear and therefore predictive learning via a direct outcome processing mechanism.