Lesions of the dorsal noradrenergic bundle impair attentional set-shifting in the rat

David Scott Tait, Verity Joy Brown, A. Farovik, D. E. Theobald, J. W. Dalley, T. W. Robbins

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126 Citations (Scopus)

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 similar to 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.

Original languageEnglish
Pages (from-to)3719-3724
Number of pages6
JournalEuropean Journal of Neuroscience
Volume25
Issue number12
DOIs
Publication statusPublished - Jun 2007

Keywords

  • 6-OHDA
  • attentional set-shifting
  • noradrenaline
  • prefrontal cortex
  • rat
  • MEDIAL PREFRONTAL CORTEX
  • LOCUS-COERULEUS
  • SELECTIVE ATTENTION
  • DOPAMINE RELEASE
  • FRONTAL-CORTEX
  • EXTRACELLULAR DOPAMINE
  • BEHAVIORAL FLEXIBILITY
  • COGNITIVE PERFORMANCE
  • SEROTONIN DEPLETION
  • CEREBRAL-CORTEX

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