Interpretation of sham feeding data: curve-shift studies

Abstract

We explored the possibility that quantitative analysis of the relationship between sucrose concentration and sham intake differentiated how various treatments affected the intake of sweet solutions. Rats were sham fed sucrose solutions varying in concentration from 0.03125 to 1.5 M. Under different treatment conditions, intake concentration functions were generated that plotted amount sham fed against sucrose concentration. Sucrose concentration that yielded 50% maximal sham intake were calculated to indicate the position of the concentration-intake function on the x-axis. Quinine adulteration of sucrose solutions and injection of 0.5 mg/kg i.p. of the dopamine antagonist pimozide reduced sham intake and shifted the concentration-intake function to the right. Lithium chloride (60 mg/kg i.p.) injected 30 min before sham feeding, a reduction of food deprivation from 18 to 6 h before sham feeding, and 6 micrograms/kg cholecystokinin octapeptide reduced sham intake equivalent amounts but did not shift the concentration-intake functions along the x-axis. The data indicate that of several factors that reduce sham feeding, only some also shift the position of concentration-intake curves, and these curve shifts may identify intake changes mediated by alterations in the processing of the taste input.

The mechanics of reinforcement

“…The expansion of a to include satiation is detailed in Killeen (1995). Changes in arousal as animals satiate can be predicted as a function of time in session, by including as parameters the effects ofthe amount or quality of an incentive (see, e.g., Weingarten, Duong, & Elston, 1996), the hunger drive, the initial deprivation level, and the threshold level of motivation that is required for responding to be initiated. Figure 4 illustrates the manner in which the response rate changes within sessions as a function ofdifferent reinforcer types and amounts.…”

Assessment of the motivation to use artificial sweetener among individuals with an eating disorder

“…Among laboratory animals, increased appetitive responding toward various drugs of abuse has repeatedly been demonstrated in chronically food-restricted animals (Cabeza de Vaca & Carr, 1998), as has been speculated to put food-restricted people at risk of binge eating episodes (Carr, 2016). In the animal model of sham feeding, reducing the duration of food deprivation limits the duration of intake, supporting a relationship at least between short-term food restriction and drive for sweet reward (Weingarten, Duong, & Elston, 1996). …”