Three groups of rats, one with amygdala lesions, one with hippocampal lesions and a control group were trained on a brightness discrimination task under one of three different conditions, enhancement of the negative cue, enhancement of the positive cue or a non-enhanced condition. Animals with amygdala lesions showed retarded learning compared with normal animals and those with hippocampal lesions under the positive cue enhancement condition. Under the negative cue enhancement condition animals with hipocampal lesions were significantly handicapped compared with the other two groups. Results are discussed in relation to the Douglas and Pribram concept of a reciprocal linking of the amygdala and hippocampal systems in discrimination learning with the amygdala functioning as a reinforce register system and the hippocampus as an error evaluation system.