Showing papers by "Harvey J. Grill published in 1982"

Contribution of the rat's neocortex to ingestive control: I. Latent learning for the taste of sodium chloride.

Abstract: Neocortical mechanisms do not directly contribute to the execution of taste discrimination, sodium appetite, or the acquisition of a taste aversion in the rat. Examination of previous studies led to the question of whether some permanent ingestive control deficit would be revealed if elements of these experimental paradigms were combined. A latent learning paradigm for the taste of salt was applied to decorticate rats. The ability of decorticate rats to associate how they obtained the taste of NaCl when sodium replete was assessed by examining bar presses during extinction when sodium depleted. Intact rats exposed to 4-6 hr of NaCl taste training retained the association after decortication; decorticate rats exposed to the same training acquired the association. What was most striking was that decorticate rats exposed to as little as 2 min of NaCl taste training demonstrated the ability to associate bar pressing with NaCl by their resistance to extinction. The association was specific to NaCl training; training with distilled water or KCl did not yield resistance to extinction during sodium depletion. Subcortical structures are therefore adequate for latent learning involving NaCl taste. Conversely, data of other investigators have revealed that the neocortex is required for the retention of taste aversion learning for the same taste.

Brain-Stem Control of Ingestive Behavior

Abstract: Hunger is a psychological construct, usually operationally defined as being directly proportional to hours of food deprivation (Silverstone, 1976), but assumed to be a neurophysiological reality. As with most psychological constructs, however, the neural substrates representing hunger have yielded slowly to neurophysiological analysis. This resistance to reductionistic assaults stems from oversimplifying the problem in the first place, and then trying to locate the oversimplification within the brain. Although neither oversimplification has been eliminated, both are now recognized, and this recognition has diverted scientific energy from the frontal assault on the hypothalamus initiated in Ranson’s laboratory and led by John Brobeck and his colleagues almost 40 years ago (Brobeck, Tepperman, & Long, 1943; Anand & Brobeck, 1951; Hetherington & Ranson, 1940) into subsidiary investigations aimed at deciphering hunger variables and integrating psychological concepts into neurophysiological analysis.