Assessment of intradimensional/extradimensional attentional set-shifting in rats

Abstract

The rat intradimensional/extradimensional (ID/ED) task, first described by Birrell and Brown 18 years ago, has become the predominant means by which attentional set-shifting is investigated in rodents: the use of rats in the task has been described in over 135 publications by researchers from nearly 90 universities and pharmaceutical companies. There is variation in the protocols used by different groups, including differences in apparatus, stimuli (both stimulus dimensions and exemplars within), and also the methodology. Nevertheless, most of these variations seem to be of little consequence: there is remarkable similarity in the profile of published data, with consistency of learning rates and in the size and reliability of the set-shifting and reversal 'costs'. However, we suspect that there may be inconsistent data that is unpublished or perhaps 'failed experiments' that may have been caused by unintended deviations from effective protocols. The purpose of this review is to describe our approach and the rationale behind certain aspects of the protocol, including common pitfalls that are encountered when establishing an effective local protocol.

Selective attention in rat visual category learning

“…An alternative interpretation of the GCM analysis is that because the attention weights to the relevant dimension were not 1.0, attention was not truly selective, and rats were therefore using the procedural system to solve the RB task. This alternative interpretation seems unlikely because there is abundant evidence for PFC-mediated selective attention in rats, supporting our view that RB learning in rats can be supported by selective attention to the relevant dimension (Ostlund 2005;Wit 2006;Marquis et al 2007;Ragozzino 2007;Yoon et al 2008;Tait et al 2014Tait et al , 2018. We therefore propose that rats have the basic attentional mechanism of the declarative system, but this mechanism is not as elaborated as the primate system, which includes rapid rule identification and rule utilization.…”

Chemogenetics reveal an anterior cingulate-thalamic pathway for attending to task-relevant information

“…For example, comparing the performance of the EGFP groups across Experiments 1 and 2, there was no difference in the magnitude of the key shift-cost measure. Furthermore, the profile of task performance of the EGFP groups in the current experiments closely match those of controls groups previously reported by both our and other groups (Chase et al, 2012;Lindgren et al, 2013;Wright et al, 2015;Powell et al, 2017;Tait et al, 2018). The unique learning profile of the experimental groups (impaired ID but facilitated ED shift performance) is similarly difficult to reconcile with an account framed in terms of off-target effects of the ligand.…”

More rapid reversal learning following overtraining in the rat is evidence that behavioural and cognitive flexibility are dissociable

“…They quickly learn to discriminate between bowls which differ by at least two stimulus attributes (or dimensions), either odor (scent added to the bowl) or haptic (the digging media) cues, but only one of which is correlated with reward. We have previously undertaken an analysis of the performance of 375 intact rats (control groups tested in 22 different experiments, by different experimenters, over 18 years) and confirmed that the odor and haptic dimensions are both learned very rapidly [33]. Although rapid learning implies this is an 'easy' task for the rat, the initial probability of responding to the relevant stimulus attribute is chance.…”

“…A second advantage is that because the rat learns the discrimination in a small number of trials, the number of over-training trials required for an ORE should also be small. We know from previous work [33] that an attentional set typically forms within 30 trials of performing successive discriminations, suggesting that, if the ORE is an attentional phenomenon, 30 additional trials should be sufficient to generate it in a bowl-digging context. We know that rats will continue to perform bowl-digging discriminations and consume the food bait (pieces of cereal) for well over 100 discrete trials in a single testing session, so this number of over-training trials, additional to the 30 or so trials of the test discriminations, is comfortably within the satiety limit.…”

“…Twenty-two female Lister hooded rats (bred in-house; University of St Andrews, from Charles River stock), were housed in pairs in 40 x 23 x 19 cm plastic cages. This was a convenience sample of female rats, but previous studies have reported that there is not a sex difference in normal rats tested in the ID/ED bowldigging paradigm, which includes reversal learning [33][34][35][36]. Therefore, there is good reason to suppose that these results would generalize to male rats.…”