Effects of hunger state on within-session response decreases under CRF schedule

Feeding behavior of rats within a single session can he well described as a linear equation of the cumulative amount of food intake. This study investigates the effect of hunger state on the parameters of the equation. Rats pressed a lever to obtain food pellets under a continuous reinforcement schedule. Response rates were regressed to the cumulative amount of intake. Two different manipulations of hunger (food deprivation duration and prefeeding) systematically altered a parameter that represented the amount of food required to terminate a meal. The amount of prefeeding was directly reflected in that parameter. Another manipulation that did not affect hunger (varying the duration of a press required to produce food) did not alter that parameter. These results suggest the parameter (the x-axis intercepts of regression lines) could be a good measure of hunger state. (C) 2000 Academic Press.