Effects of food restriction on the conditioned reinforcing properties of an opioid-associated stimulus.

Food restriction promotes drug self-administration; however, the effects of food restriction on the conditioned reinforcing properties of drug-associated stimuli are less clear. We tested the extent to which food restriction modified the conditioned reinforcing properties of a remifentanil-associated stimulus following conditioning with 3.2 or 1.

Effects of dose on acquisition and persistence of a new response for a remifentanil-associated stimulus.

Previous research demonstrated that a remifentanil-associated stimulus facilitated the acquisition of a previously unlearned response; however, it is unclear how long a remifentanil-associated stimulus maintains conditioned reinforcing properties under conditions of daily testing. To address this gap, we exposed adult male rats to response-independent stimulus presentations and deliveries of remifentanil (1.0, 3.

Comparison of potentially real versus hypothetical food outcomes in delay and probability discounting tasks.

Much of the research on human delay and probability discounting involves the use of hypothetical outcomes, in which participants indicate preferences for outcomes but do not receive them. Research generally shows that hypothetical and potentially real outcomes are discounted at similar rates. One study, however, shows that potentially real cigarettes are discounted more steeply than hypothetical cigarettes in smokers, calling into question the generality of the finding that potentially real and hypothetical money are discounted at similar rates.

Effects of a cafeteria diet on delay discounting in adolescent and adult rats: Alterations on dopaminergic sensitivity.

Diet-induced obesity is a laboratory procedure in which nonhuman animals are chronically exposed to a high-fat, high-sugar diet (i.e. cafeteria diet), which results in weight gain, altered sensitivity to reward, and alterations in the dopamine D system.

High-fat diet alters weight, caloric intake, and haloperidol sensitivity in the context of effort-based responding.

High-fat (HF) diets result in weight gain, hyperphagia, and reduced dopamine D2 signaling; however, these findings have been obtained only under free-feeding conditions. This study tested the extent to which HF diet affects effort-dependent food procurement and the extent to which dopamine signaling is involved. Male Sprague-Dawley rats consumed either a HF (n=20) or a standard-chow (n=20) diet.

The utility of behavioral economics in expanding the free-feed model of obesity.

Animal models of obesity are numerous and diverse in terms of identifying specific neural and peripheral mechanisms related to obesity; however, they are limited when it comes to behavior. The standard behavioral measure of food intake in most animal models occurs in a free-feeding environment. While easy and cost-effective for the researcher, the free-feeding environment omits some of the most important features of obesity-related food consumption-namely, properties of food availability, such as effort and delay to obtaining food.