Social skill deficits remain a defining feature of autism. One method to explain social behavior in autism is to explore specific antecedent-response relations. People with autism do not attend to social cues as readily as their typically developing peers thereby missing important cues that guide behavior during social interactions. The current study explored how children with autism learn antecedent-response relations using social and nonsocial stimuli as cues for reinforcement. A computerized task comprised pictures of social and non-social stimuli were presented on a computer screen. Participants were asked to respond to each picture by pressing a button if they thought pressing the button in the presence of the picture would earn them a reinforcer or to withhold pressing if they thought the picture would not earn them a reinforcer. Neither typically-developing children nor children diagnosed with ASD were able to reliably discriminate pictures. Developmental implications of these findings are discussed. / October 2015

Food restriction has been shown to affect responding for reward and has been manipulated to devalue reward. Reward density has been shown to alter responding in both first-order schedules and chain schedules. Devaluation has differential effects in first-order schedules and the links of chain schedules. The objective of the current study was to analyze the reward devaluation effect in a two-link chain schedule by manipulating food restriction and reward density in the proximal link; these variables had previously not been studied systematically. The chain schedule required rats to lever press according to a random interval 120-s schedule to turn on a light conditioned stimulus (CS). In the presence of the CS rats were rewarded for pulling a chain; the chain was active on a variable ratio (VR) 5 schedule of reinforcement for some rats, while the chain was on continuous reinforcement (CRF) for the other rats. Food restriction protocols were either 1-hr daily free feeding (1-hr feeding) or a daily ration to maintain weight at 80% of free feed controls (ration). Devaluing the CS while in the isolated proximal link was done by exposing trained rats to sessions of chain pulling in the presence of the CS but withholding reward. In subsequent lever press sessions without the CS, decreased responding was seen in rats that had undergone the devaluation procedure, but only in rats on the 1-hr feeding protocol. This devaluation effect was found in both the CRF and VR 5 schedules. Subsequent tests of lever pressing for the CS also revealed decreased responding. Post-test CS discrimination sessions demonstrated CS devaluation that has not been demonstrated previously. These results demonstrate that the isolated devaluation of the proximal link in a heterogeneous two-link chain schedule can result in decreased responding in the isolated first link. This effect is dependent on sufficient food restriction and demonstrates a measurable devaluation effect which is independent of the reward being present. This study also demonstrated that isolated devaluation of the second link can be subsequently measured in a post-test CS discrimination re-acquisition session regardless of food restriction, which had no significant effect in the session. The devaluation effect has not been demonstrated in a re-acquisition session before, rather responding in previous re-acquisition sessions were only affected by food restriction. / Thesis (Master, Psychology) -- Queen's University, 2007-09-11 11:49:20.814

Cannabinoid agonists, including marijuana containing delta-9-tetrahydrocannabinol (THC), are found rewarding by humans. In addition to human self-reports and experimental studies that show marijuana is rewarding, contributions from preclinical studies also have implicated cannabinoid receptors in reward-motivated behavior. One way to assess these preclinical effects of cannabinoids is intracranial self-stimulation (ICSS), where an animal performs a response to receive electrical stimulation of a specific brain area or circuit known to be involved in reward. Drugs of abuse, such as psychomotor stimulants, facilitate responding for ICSS. While a few studies have shown facilitating effects of cannabinoids in rats, several have shown the opposite effect, and no studies so far have evaluated cannabinoids in mouse ICSS. Furthermore there are no studies evaluating specific inhibitors of endocannabinoid catabolic enzymes in ICSS in any species. In these studies we assessed the cannabinoid agonist THC, as well as the fatty acid amide hydrolase (FAAH) inhibitor, PF-3845, the monoacylglycerol lipase (MAGL) inhibitor JZL184, and the combined FAAH/MAGL inhibitor SA-57 in ICSS of the medial forebrain bundle in C57BL/6 mice. Additionally, we assessed the psychomotor stimulant cocaine as a positive control to facilitate ICSS. These studies were complimented with spontaneous locomotor activity and food-maintained operant experiments to assess the sensitivity of ICSS to cannabinoids. Additionally, brain endocannabinoid levels were measured in brain regions associated with the mesolimbic system after enzyme inhibitor treatments. THC, JZL184, and SA-57 all produced time-dependent reductions in ICSS that were mediated through CB1 receptors, as they were blocked by pre-treatment with the CB1 antagonist rimonabant, but not with the CB2 antagonist SR144528. PF-3845 also reduced ICSS, but did so independent of CB1 and CB2 receptors, and only with one dose (30.0 mg/kg) that has not been assessed previously in vivo. We showed that ICSS was more sensitive to the rate-reducing effects of cannabinoids than other measures of behavior with motor components including spontaneous locomotor activity and operant nose-poking for food, and that the reduction of ICSS produced by both JZL184 and SA-57 is accompanied by increases in 2-AG in mesolimbic brain areas. Thus, cannabinoids do not facilitate ICSS in C57BL/6 mice over a range of doses and pre-treatment times, similar to most studies with rats. These data suggest that cannabinoids may produce rewarding effects through non-mesolimbic areas of the brain.

Motivating individuals with autism can be challenging for clinicians and educators seeking to increase skills or decrease problem behaviors. Even when highly preferred reinforcers have been identified, they tend to lose their effectiveness over time. Over the years, several strategies have been developed to maintain the effectiveness of reinforcers. Reinforcer variation has been demonstrated to attenuate decreases in responding associated with repeated exposure to a single reinforcer. Another strategy that has been used to help maintain responding is allowing an individual a choice among reinforcers. Several researchers have suggested that providing choice among several reinforcers may produce the same effects on responding as reinforcer variation. Although these two procedures have been shown to maintain motivation in individuals with autism, they have not been systematically compared and evaluated against each other. In this study, we evaluated the effects of reinforcer variation as compared to reinforcer choice.