Substitution and Caloric Regulation in a Closed Economy

Abstract

Three experiments were conducted to study the effect of an imperfect substitute for food on demand for food in a closed economy. In Experiments 1 and 2, rats pressed a lever for their entire daily food ration, and a fixed ratio of presses was required for each food pellet. In both experiments, the fixed ratio was held constant during a daily session but was increased between sessions. The fixed ratio was increased over a series of daily sessions once in the absence of concurrently available sucrose and again when sucrose pellets were freely available. For both series, increases in the fixed ratio reduced food intake, but body weight was reduced only in the no-sucrose condition. In the sucrose condition, body weight and total caloric intake (sucrose plus food) were relatively unaffected by increases in the fixed ratio. At all fixed ratios, food intake was proportionally reduced by the intake of sucrose. In Experiment 3, monkeys obtained food or saccharin by pressing keys; the fixed ratio of presses per food pellet was increased once when tap water was each monkey's only source of fluid, again when each monkey's water was sweetened with saccharin, and a third time when each monkey had concurrent access to the saccharin solution and plain water. Increases in the fixed ratio, but not the intake of the saccharin solution, reduced each monkey's food intake. Because neither rats' sucrose nor monkeys' saccharin intakes affected the slope of the respective demand curves for food, monkeys and rats increased their daily output of presses and thereby defended their daily intake of those complementary elements of food. However, sucrose reduced rats' food intake. The relative constancy of body weight and total caloric intake in the sucrose condition is consistent with the possibility that rats tended to regulate caloric intake.

Secondary Hypoxemia Exacerbates the Reduction of Visual Discrimination Accuracy and Neuronal Cell Density in the Dorsal Lateral Geniculate Nucleus Resulting from Fluid Percussion Injury

“…However, mean intake for group SH was significantly larger than the mean intakes for groups IH and IN from day 15 though day 22. Since rats in the present study might have attempted to maintain a constant daily food intake (Bauman, 1991(Bauman, , 1996, this significant increase in intake in the light period might explain the consistently reduced mean intake of group SH in the dark period from day 15 through day 22.…”

“…As a consequence, the unchanged dLG in the contralateral hemisphere and perhaps regenerative sprouting (Cheng and Povlishock, 1986) might have supported relearning of the visual discrimination. The secondary and conceivably related reason is that, in contrast to the previous laboratory studies of the neurologica l, behavioral, and mnemonic deficits that result from traumatic brain injury, the present procedure required rats to repeatedly execute the visual discrimination for access to their entire daily food intake (Bauman, 1991;Bauman et al, 1996). As a consequence, repeated practice could have greatly supported relearning of the discrimination.…”

Relative Reinforcing Strength of ThreeN-Methyl-d-Aspartate Antagonists with Different Onsets of Action

“…As ratios increased above this value, rates declined again. The low rates occurring with low fixed ratio values have been observed in situations where reinforcers other than drug are available (Hursh, 1984;Hursh et al, 1988;Bauman et al, 1996). These low rates may be due primarily to the rate-decreasing effects of accumulated reinforcers (e.g., satiation).…”

Supply of a Nondrug Substitute Reduces Escalated Heroin Consumption

“…For instance, Hursh et al, 1988 observed that the demand for food is initially inelastic with increasing response requirements (ie food consumption decreases less than price increases) and then becomes elastic above a specific response requirement (ie food consumption decreases more than price increases). Importantly, the demand for food is influenced by the availability of substitutes for food (eg Lea and Roper, 1977;Bauman et al, 1996;Collier and Johnson, 2000). For instance, Lea and Roper (1977) showed in a two-compartment operant chamber that food consumption in one chamber was more sensitive to increases in response requirement when food was available in the other chamber.…”