Catecholamines and aversive learning: a review.

Experimental evidence is reviewed for the implication in aversive learning of the catecholamines, in particular noradrenaline and dopamine and the pituitary-adrenocortical system, in particular adrenocorticotrophic hormone and corticosterone. Depending on task difficulty peripheral neural noradrenaline may be an important factor in aversive learning whereas brain catecholamines are important regardless of task difficulty. The adrenocortical system, as indexed by plasma levels of corticosterone, is also implicated in complex aversive tasks. To date, no convincing empirical evidence exists for a link mechanism between the brain catecholamine system and the adrenocortical system following aversive learning. Earlier behavior theories of aversive learning are reformulated in the light of more recent findings on neuroregulation.