Differential effects of social and novelty enrichment on individual differences in impulsivity and behavioral flexibility

Abstract

Early life experience profoundly impacts behavior and cognitive functions in rats. The present study investigated how the presence of conspecifics and/or novel objects, could independently influence individual differences in impulsivity and behavioral flexibility. Twenty-four rats were reared in an isolated condition, an isolated condition with a novel object, a pair-housed social condition, or a pair-housed social condition with a novel object. The rats were then tested on an impulsive choice task, a behavioral flexibility task, and an impulsive action task. Novelty enrichment produced an overall increase in impulsive choice, while social enrichment decreased impulsive choice in the absence of novelty enrichment and also produced an overall increase in impulsive action. In the behavioral flexibility task, social enrichment increased regressive errors, whereas both social and novelty enrichment reduced never reinforced errors. Individual differences analyses indicated a significant relationship between performance in the behavioral flexibility and impulsive action tasks, which may reflect a common psychological correlate of action inhibition. Moreover, there was a relationship between delay sensitivity in the impulsive choice task and performance on the DRL and behavioral flexibility tasks, suggesting a dual role for timing and inhibitory processes in driving the interrelationship between these tasks. Overall, these results indicate that social and novelty enrichment produce distinct effects on impulsivity and adaptability, suggesting the need to parse out the different elements of enrichment in future studies. Further research is warranted to better understand how individual differences in sensitivity to enrichment affect individuals’ interactions with and the resulting consequences of the rearing environment.

An automated home-cage-based 5-choice serial reaction time task for rapid assessment of attention and impulsivity in rats

“…A potential caveat of the SP-5-CSRTT is that rats were housed individually in CombiCages. Social isolation in rats can lead to increased stress levels and altered neuroendocrine state, particularly during early weaning (Serra et al 2000; Weiss et al 2004; Weintraub et al 2010), which has been found to impact executive functions in rats (Kirkpatrick et al 2013; Wang et al 2017). Notably, these effects are most pronounced when social isolation occurs following early weaning, for instance starting at postnatal day 21.…”

Dietary effects on the determinants of food choice: Impulsive choice, discrimination, incentive motivation, preference, and liking in male rats

“…impulsive choice delay task followed by the time discrimination task or impulsive choice magnitude task followed by the reward magnitude discrimination task). Between the impulsive choice and the discrimination tasks, a buffer task was administered to reduce side biases and carry-over effects (Wang, Marshall, & Kirkpatrick, 2017). After the first set of impulsive choice and discrimination tasks, the rats completed another buffer task and the lever assignments were switched before beginning the next set of impulsive choice and discrimination tasks to minimize carryover effects.…”

“…Buffer task.-A modification of the lever press training was used in between each task to minimize side biases and the carryover effects from one task to another. Wang et al (2017) found that the buffer task minimized cross-task interference and eliminated side biases. The first session delivered FR1 → RR3 → RR5 schedules from lever press training where each schedule was trained for one block with 20 reinforcers earned on each lever, constituting three blocks in total.…”

Enhancing cognition through pharmacological and environmental interventions: Examples from preclinical models of neurodevelopmental disorders

“…Finally, the effects of social versus the non-social (novelty, exercise, etc.) components of enrichment are also dissociable by several measures including brain weight that is more responsive to environment complexity than social conditions (Rosenzweig et al, 1978), and differential effects on impulsivity, behavioral flexibility, and memory (Prado Lima et al, 2018;Wang et al, 2017).…”