DRL performance, extinction, and secondary reinforcement: role of appetitive value of food in mice with septal lesions.

Normal mice and mice with septal lesions were trained on a differential-reinforcement-for-low-rates-of-responding (DRL 8-sec) schedule for the reinforcement varying in incentive value. Dilution of diet increased the number of reinforcements received by mice with septal lesions. In Experiments 2 and 3 the effects of septal lesions on resistance to extinction and continuous reinforcement training and the strength of secondary reinforcement were investigated. Changes in reinforcement value modified the septal lesion effects in both cases. All three experiments demonstrated the alteration of the septal lesion effect through a change in the appetitive value of the reinforcement. The results suggest that one of the mechanisms by which septal lesions impair DRL performance is an enhancement of reinforcing properties of food.