Continuous reinforcement of responding for water in rats with medial or dorsolateral septal lesions: Effect of deprivation level

Abstract

The purpose of the present study was to examine differential effects of medial and dorsolateral septal lesions and level of water deprivation on lever pressing for water using a continuous reinforcement schedule. Five levels of water deprivation were used: 0, 6, 12, 24, and 48 hr. In addition to lever presses for water, responses on a second lever which were reinforced by onset of the cue lights above this lever and the amount of time the rat spent in the part of the cage where there were no levers were also recorded. The results showed that rats with dorsolateral, but not medial, septal lesions were significantly hypoactive when little deprived. These rats had reduced water-reinforced lever-press response rates when the level of deprivation was either 6 or 12 hr; they had reduced rates of sensory-reinforced (light-onset) responses and spent less time in the part of the cage most distant from the levers. Neither of the groups differed in ad libitum water intake. It is concluded that rats with dorsolateral, but not medial, septal lesions are hypomotivated when the level of water deprivation is low.