Although sensation seeking or novelty seeking is a reliable predictor of drug use in humans, individual differences in free-choice novelty seeking in animal models have generally failed to predict drug use. In the current article, hierarchical multiple regression analyses were used on data collected from a large sample of rats. Rats were screened on measures of inescapable and free-choice novelty tests and then were trained to lever press for sucrose or intravenous amphetamine. Although scores from the inescapable novelty test weakly predicted responding for amphetamine, the addition of free-choice novelty preference scores into the regression analyses significantly improved the predictive models. These results indicate that, similar to evidence in humans, individual differences in novelty seeking may be able to predict drug use in rats.

These results suggest that environmental enrichment during development reduces the stimulant effect of nicotine.

Rats reared in an IC show greater proclivity to respond operantly for 10% ethanol compared with rats raised in either SC or EC (which did not differ from each other). These findings agree with a number of studies that have shown isolate reared animals to consume greater amounts of ethanol compared with their socially reared counterparts yet contrast some studies showing EC animals consume greater amounts of ethanol than IC rats. The current findings illustrate that rearing environment also plays an important role in an animal's proclivity to respond for ethanol.

The Basso, Beattie and Bresnahan (BBB) locomotor rating scale is widely used to test behavioral consequences of spinal cord injury (SCI) to the rat. Sensitivity of this rating scale can differentiate hind limb locomotor skills over a wide range of injury severities. While the 21-point BBB scale is ordinal in nature, the present discussion recommends the use of parametric statistics to evaluate the locomotor results. Specifically, it defines appropriate statistical analysis of these data in order to facilitate interpretation of results between laboratories and to provide a common methodology for the correct interpretation of SCI behavioral data.

Previous research has indicated that rearing in an enriched environment may promote self-control in an impulsive choice task. To further assess the effects of rearing environment on impulsivity, 2 experiments examined locomotor activity, impulsive action, impulsive choice, and different aspects of reward sensitivity and discrimination. In Experiment 1, rats reared in isolated or enriched conditions were tested on an impulsive choice procedure with a smaller-sooner versus a larger-later reward, revealing that the isolated rats valued the smaller-sooner reward more than the enriched rats. A subsequent reward challenge was presented in which the delay to the 2 rewards was the same but the magnitude difference remained. The enriched rats did not choose the larger reward as often as the isolated rats, reflecting poorer reward discrimination. Impulsive action was assessed using a differential-reinforcement-of-low-rate task, which revealed deficits in the enriched rats. In Experiment 2, rats reared in isolated, standard, or enriched conditions were tested on reward contrast and reward magnitude sensitivity procedures. The rats were presented with 2 levers that delivered different magnitudes of food on variable interval 30-s schedules. Across all tests, the enriched and social rats displayed more generalized responding to the small-reward lever, but a similar response to the large-reward lever, compared with the isolated rats. This confirmed the results of Experiment 1, indicating poorer reward discrimination in the enriched condition compared with the isolated condition. The results suggest that enrichment may moderate reward generalization/discrimination processes through alterations in incentive motivational processes.