Instrumental Learning of Urine Formation by Rats; Changes in Renal Blood Flow
This chapter aims to show whether or not the volume of urine formed by rats, and attendant changes in glomerular filtration and renal blood flow, could be increased or decreased, respectively, by instrumental learning. Rats paralyzed by curare and maintained on artificial respiration were rewarded by electrical stimulation of the medial forebrain bundle for changes in the rate of urine formation. Rewarding half of the rats, selected at random, in the main experiment for increasing and the other half for decreasing their rates of urine formation controlled for any unconditioned or progressive effects of the electrical stimulation of the lateral hypothalamus used as a reward. In classical conditioning, the reinforcement must be a stimulus that has the unconditioned ability to elicit the specific response to be conditioned. In instrumental learning the reinforcement, usually called a reward, does not need to be able to elicit the response to be learned; it has the property of strengthening any immediately preceding response.