David S Tait

Publications (3)11.34 Total impact

• Article: Lesions of the orbital prefrontal cortex impair the formation of attentional set in rats.

  E Alexander Chase, David S Tait, Verity J Brown
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  ABSTRACT: In rats, reversal learning impairments are commonly reported after lesions of the orbital prefrontal cortex (OFC), in contrast to the effect of lesions of the medial prefrontal cortex, which impair attentional set-shifting. Comparable dissociations have also been reported in humans, monkeys and mice. However, these two manifestations of behavioural flexibility may share common cognitive processes. The present study tested the hypothesis that lesions of the OFC (an area that integrates expected and actual outcomes to signal which cues in the environment predict reward) would impair the formation of attentional set as well as impairing reversal learning. We compared the performance of lesioned and control rats on two set-shifting tasks. The first task we used, 'the 4ID task', had no reversal stages, but multiple intradimensional acquisitions before the extradimensional shift stage, to assess set-formation as well as set-shifting. The second task was the standard intradimensional/extradimensional '7-stage task', which includes reversal learning stages after each compound acquisition. Compared with controls, lesioned rats were slower to form attentional set on the 4ID task. When they did form a set, they required more trials to complete the extradimensional shift stage. On the 7-stage task, we replicated our previous finding of impaired reversal learning and reduced shift-costs. We interpret these findings as reflecting a single deficit in identifying relevant cues after unexpected outcomes, which supports recent models of OFC function. Our findings challenge the assumption that the contribution of the OFC to behavioural flexibility is limited to reversal learning.
  European Journal of Neuroscience 06/2012; 36(3):2368-75. · 3.63 Impact Factor
• Article: Lesions of the dorsal noradrenergic bundle impair attentional set-shifting in the rat.

  David S Tait, Verity J Brown, Anja Farovik, David E Theobald, Jeffrey W Dalley, Trevor W Robbins
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  ABSTRACT: Rats with medial prefrontal cortex (mPFC) lesions are impaired in attentional set-shifting, when it is required to shift to a previously irrelevant perceptual dimension. The main source of noradrenergic input to the mPFC is from the locus coeruleus via the dorsal noradrenergic ascending bundle (DNAB). This study examined the effects of selective cortical noradrenaline depletion following 6-hydroxydopamine-induced lesions of the DNAB on attentional set-shifting and other aspects of discrimination learning and performance. Rats learned to dig in baited bowls, and then acquired discriminations based on one of two aspects of a bowl--odour or digging medium. The task tested acquisition of novel discriminations (both intra- and extra-dimensional) and reversal learning when contingencies were reversed with the same stimuli. At the conclusion of testing, the DNAB-lesioned rats were shown to have a selective depletion of noradrenaline of approximately 70% within the mPFC (cingulate and prelimbic cortex subregions), with no other significant changes in dopamine or 5-hydroxytryptamine. Rats required more trials to learn new discriminations when attentional shifting was required [extra-dimensional (ED)-shift]. Rats with dorsal noradrenergic ascending bundle (DNAB) lesions were impaired in novel acquisitions when an ED-shift was required, but were unimpaired in reversal learning and other aspects of discrimination learning, relative to controls. These data are consistent with other evidence implicating noradrenaline (NA) in attentional set-shifting, and contrast with effects of manipulations of 5-hydroxytryptamine (5-HT) and acetylcholine within the medial prefrontal cortex (mPFC). The findings are also relevant to recent theorizing about the functions of the coeruleo-cortical noradrenergic system.
  European Journal of Neuroscience 07/2007; 25(12):3719-24. · 3.63 Impact Factor
• Article: 5-HT6 receptor antagonists improve performance in an attentional set shifting task in rats.

  Paula D Hatcher, Verity J Brown, David S Tait, Simon Bate, Philip Overend, Jim J Hagan, Declan N C Jones
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  ABSTRACT: Performance on the Wisconsin Card Sorting Test (WCST), which requires patients to 'shift attention' between stimulus dimensions (sorting categories), is impaired in diseases such as schizophrenia. The rat attentional set shifting task is an analogue of the WCST. Given that 5-HT(6) receptor antagonists improve cognitive performance and influence cortical neurochemistry in rats, the present study investigated the effects of 5-HT(6) receptor antagonists upon attentional set shifting in rats. Rats were tested in this paradigm following sub-chronic SB-399885-T or SB-271046-A (both 10 mg kg(-1) bid, p.o. for 8 days prior to testing and either 4 or 2 h prior to testing on day 9, respectively). Rats were trained to dig in baited bowls for a food reward and to discriminate based on odour or digging media (Habituation, day 8). In a single session (day 9), rats performed a series of discriminations, including reversals (REV), intra-dimensional (ID) and extra-dimensional (ED) shifts. Neither compound altered performance during Habituation. On the test day, both SB-399885-T and SB-271046-A reduced the total trials to reach criterion and the total errors made when data were collapsed across all discriminations (P<0.05-0.01). Further, both compounds significantly reduced the trials to criterion for REV-1 (P<0.05-0.01) and abolished the ID/ED shift. SB-399885-T, but not SB-271046-A, reduced trials required to complete the ED shift (P<0.05) and the number of errors made during completion of the ID (P<0.05) and ED shifts (P<0.01). 5-HT(6) receptor antagonists improved performance in the attentional set shifting task and may have therapeutic potential in the treatment of disorders where cognitive deficits are a feature, including schizophrenia.
  Psychopharmacologia 09/2005; 181(2):253-9. · 4.08 Impact Factor