Rats with electrodes in the lateral hypothalamus, which elicit both self-stimulation and drinking, were presented with quinine solutions, saccharine solutions, and water while self-stimulating. Quinine significantly reduced the volume ingested during electrically-induced drinking, whereas saccharin increased the volume; a significant decrease in concurrent self-stimulation rate accompanied electrically-induced drinking of quinine solution and a significant increase accompanied ingestion of saccharine solution. An experiment to study the effects of no water, water, and saccharin on self-stimulation rate revealed a significant increase while Ss were drinking water and an additional increase when Ss were drinking saccharine solution.Satiated rats with electrodes terminating in a small region of the lateral hypothalamus will self-stimulate and drink water (Mogenson & Stevenson, 1966. The electrical stimulation reinforces lever presses and, because of the unique locus of stimulation, it also induces the animal to drink. From Pfaffmann (1960) it is thought that the "affective consequences of sensory stimulation [p. 265]" are mediated by the visceral brain. Sweet taste, which produces positive affect, and bitter taste, which produces negative affect, should influence the integrative systems in the visceral brain concerned with intracranial stimulation (ICS) and drinking behavior. In order to investigate this possibility, saccharin or quinine were added to the water ingested during ICS. METHOD SubjectsMale Wistar rats, 3-5 mo. of age and weighing 450-575 gm., were housed in individual wire mesh cages in a controlled environment of 40%1 The authors wish to thank J. A. F. Stevenson for critically reading the manuscript and providing valuable comments. Thanks are also extended to M. Dinning for her technical assistance.

Two groups of rats, 'shifted' (32-4% sucrose) and 'unshifted' (4-4% sucrose), were given access to sucrose solutions for 5 min/day for 10 days. On day 11, shifted animals had access to a devalued incentive (4% sucrose) and subgroups of each group received doses of amisulpride (10 or 60 mg/kg, i.p.) or its vehicle before a 10-min access period to sucrose solutions. Lick frequency was measured both pre- and post-shift. A high dose of amisulpride reduced successive negative contrast (SNC) after a brief period of exposure to the devalued stimulus, whereas a low dose had no effect. The acute effects of high doses of amisulpride seem to act on contrast effects in a similar way to anxiolytic compounds such as the benzodiazepine, chlordiazepoxide.

Rats on a 23-hr food and water deprivation schedule were tested for preference between lever pressing for electrical stimulation of the lateral hypothalamus and liquid rewards, which varied in taste and caloric content. Preference for self-stimulation diminished as the alternative liquid became more palatable: with a saccharineglucose solution as the alternative the animals showed an equal preference for hypothalamic stimulation and the liquid reward. In longer 6-hr tests, rats deprived of water for 24 and 48 hr initially showed a preference for self-stimulation over water but eventually satisfied their water deficit by pressing for water. Neglect of physiological needs during self-stimulation appears to be more a function of the alternatives available and the length of the test session than intrinsic properties of the brain stimulation.