Effects of septal lesions on responding for delayed brain stimulation reinforcement

Rats with medial septal lesions were unable to learn in a situation where lateral hypothalamic stimulation reinforcement was delayed for 10 sec following each response. Rats with lateral septal lesions and rats with no lesions were able to learn under these conditions. All subjects in all groups exhibited high rates of responding for stimulation delivered concurrently with the response. The data suggest that a fiber system (possibly adrenergic) ascending from lateral hypothalamus through the medial septal area is involved in the mediation of brain stimulation reinforcement of complex tasks; and that some other neural mechanism which mediates the reinforcement of simple tasks must also exist.