Probabilistic contingency learning with limbic or prefrontal damage

A fundamental capacity of the human brain is to learn relations (contingenc ies) between environmental stimuli and the consequences of their occurrence . Some contingencies are probabilistic; that is, they predict an event in s ome situations but not in all. Animal studies suggest that damage to limbic structures or the prefrontal cortex may disturb probabilistic learning. Th e authors studied the learning of probabilistic contingencies in amnesic pa tients with limbic lesions, patients with prefrontal cortex damage, and hea lthy controls. Across 120 trials, participants teamed contingent relations between spatial sequences and a button press. Amnesic patients had learning comparable to that of control subjects but failed to indicate what they ha d learned. Across the last 60 trials, amnesic patients and control subjects learned to avoid a noncontingent choice better than frontal patients. Thes e results indicate that probabilistic learning does not depend on the brain structures supporting declarative memory.