Abstract:

Attentional set-shifting task (AST) is a newly developed rodent-based model that can be used to specifically evaluate cortically-mediated cognitive flexibility. The AST has been increasingly used to investigate the neural basis underlying cognitive flexibility and related disorders. In the present study, we investigated the effects of strain and testing protocol on cognitive function by comparing the performance during different cognitive stages in the AST, between Sprague-Dawley (SD) and Wistar rats, and between a seven-stage and five-stage AST. Our data showed differences in cortically-mediated cognitive function between SD and Wistar rats when they were tested in both seven-stage and five-stage AST. In general, Wistar rats exhibited better performance in each stage of the AST compared with SD rats. Especially in the reversal learning (RL) stage, Wistar rats required fewer trials to reach the criterion and lower error rates compared with SD rats, suggesting better cognitive flexibility in strategy shifting. In contrast, the reactive pattern between different cognitive stages (simple discrimination, SD; compound discrimination, CD; intra-dimensional shifting, IDS; reversal learning, RL; extra-dimensional shifting, EDS) in the AST did not significantly differ by strain or testing protocol. Theoretically, there is a general response pattern across these cognitive stages, namely, more trials to reach criterion and/or higher error rates are generally seen during higher complexity learning stages (i.e. RL and EDS) than in simpler learning stages (i.e. SD and CD), which is a prerequisite for the interpretation of performance in the RL and EDS in terms of strategy and attentional set-shifting. Consistent with this, we found that both SD and Wistar rats required more trials to reach criterion and showed higher error rates during RL and/or EDS stages than other stages in both the five-stage and seven-stage AST, demonstrating a stable reactive pattern of set establishment and set shifting in the AST. These results suggest that there are strain differences in cortically-mediated cognitive flexibility in rats, and constructive relationship across different cognitive components in the AST is stable across rat strain and testing protocol. These findings extend the extant knowledge of the AST model and provide a behavioral basis for the selection of experimental animal and testing protocols for the AST in further studies.

Key words: cognitive flexibility, attentional set-shifting, strain differences, reversal learning, extradimensional shifting