Polydipsia induced by a schedule of brain stimulation reinforcement

Rats pressed a lever for a signaled brain stimulation reinforcement on either fixed-interval or fixed-ratio schedules. Both schedules induced polydipsia, with a median water intake of 22.5 ml (about four times the control level) in 3-hr sessions. The stimulation did not directly elicit drinking or other behaviors. In a second experiment, two out of four rats became polydipsic during extinction following a continuous schedule of brain stimulation reinforcement. The results were compared with previous attempts to induce polydipsia with a schedule of brain stimulation reinforcement and were discussed in terms of polydipsia as a model of human “compulsive” behaviors.