Considerable evidence suggests that the learning and performance of instrumental actions depend on activity in basal ganglia circuitry; however, these two functions have generally been considered independently. Whereas research investigating the associative mechanisms underlying instrumental conditioning has identified critical cortical and limbic input pathways to the dorsal striatum, the performance of instrumental actions has largely been attributed to activity in the dorsal striatal output pathways, with direct and indirect pathway projection neurons mediating action initiation, perseveration and cessation. Here, we discuss evidence that the dorsal striatal input and basal ganglia output pathways mediate the learning and performance of instrumental actions, respectively, with the dorsal striatum functioning as a transition point. From this perspective, the issue of how multiple striatal inputs are integrated at the level of the dorsal striatum and converted into relatively restricted outputs becomes one of critical significance for understanding how learning is translated into action. So too does the question of how learning signals are modulated by recent experience. We propose that this occurs through recurrent corticostriatothalamic feedback circuits that serve to integrate performance signals by updating ongoing action-related learning.

The posterior dorsomedial striatum (pDMS) is necessary for goal-directed action; however, the role of the direct (dSPN) and indirect (iSPN) spiny projection neurons in the pDMS in such actions remains unclear. In this series of experiments, we examined the role of pDMS SPNs in goal-directed action in rats and found that whereas dSPNs were critical for goal-directed learning and for energizing the learned response, iSPNs were involved in updating that learning to support response flexibility. Instrumental training elevated expression of the plasticity marker Zif268 in dSPNs only, and chemogenetic suppression of dSPN activity during training prevented goal-directed learning. Unilateral optogenetic inhibition of dSPNs induced an ipsilateral response bias in goal-directed action performance. In contrast, although initial goal-directed learning was unaffected by iSPN manipulations, optogenetic inhibition of iSPNs, but not dSPNs, impaired the updating of this learning and attenuated response flexibility after changes in the action-outcome contingency.

Neuropsychiatric research has utilized cognitive testing in rodents to improve our understanding of cognitive deficits and for preclinical drug development. However, more sophisticated cognitive tasks have not been as widely exploited due to low throughput and the extensive training time required. We developed a modified signal detection task (SDT) based on the growing body of literature aimed at improving cognitive testing in rodents. This study directly compares performance on the modified SDT with a traditional test for measuring attention, the 5-choice serial reaction time task (5CSRTT). Adult male Sprague-Dawley rats were trained on either the 5CSRTT or the SDT. Briefly, the 5CSRTT required rodents to pay attention to a spatial array of five apertures and respond with a nose poke when an aperture was illuminated. The SDT required the rat to attend to a light panel and respond either left or right to indicate the presence of a signal. In addition, modifications were made to the reward delivery, timing, control of body positioning, and the self-initiation of trials. It was found that less training time was required for the SDT, with both sessions to criteria and daily session duration significantly reduced. Rats performed with a high level of accuracy (>87%) on both tasks, however omissions were far more frequent on the 5CSRTT. The signal duration was reduced on both tasks as a manipulation of task difficulty relevant to attention and a similar pattern of decreasing accuracy was observed on both tasks. These results demonstrate some of the advantages of the SDT over the traditional 5CSRTT as being higher throughput with reduced training time, fewer omission responses and their body position was controlled at stimulus onset. In addition, rats performing the SDT had comparable high levels of accuracy. These results highlight the differences and similarities between the 5CSRTT and a modified SDT as tools for assessing attention in preclinical animal models.

Developmental vitamin D (DVD) deficiency is a plausible risk factor for schizophrenia that has been associated with behavioural alterations including disruptions in latent inhibition and response inhibition. The rodent gambling task (rGT) assesses risk-based decision-making, which is a key cognitive deficit observed in schizophrenia patients. The primary aim of this study was to examine risk-based decision-making in DVD-deficient and control rats on the rGT. We also evaluated the performance of female Sprague-Dawley rats on the rGT for the first time. Adult male and female Sprague-Dawley rats from control and vitamin D deficient dams were trained to perform the rGT in standard operant chambers and their performance and choice-preferences were assessed. Female rats were significantly faster to reach rGT training criteria compared with male rats and DVD-deficient rats were faster to reach training criteria than control animals. After reaching stable performance on the rGT DVD-deficient and control rats showed a significant preference for the optimal choice-option in the rGT, but there were no significant effects of sex or diet on these responses. DVD deficiency did not alter the decision-making processes on the rGT because no significant changes in choice-preferences were evident. This is the first study to demonstrate that once established, the performance of females is comparable to male Sprague-Dawley rats on the rGT.