The present thesis investigates the role of the prefrontal cortex and cholinergic modulation in attentional performance, and to a lesser extent, inhibitory response control, in rats. A greater understanding of these functions is important for the effective treatment of attentional and impulsive control deficits, present in a range of neuropsychiatric disorders. For this field to progress, the assessment of attentional performance in a similar manner across humans and animals is crucial. In the present thesis, attentional performance was assessed on the novel, touchscreen-based rodent continuous performance task (rCPT), which assesses sustained, focused attention in essentially an identical manner to CPTs commonly used in the clinic. Findings were compared to performance on the well-characterised 5-choice serial reaction time task (5-CSRTT), which assesses sustained, spatial divided attention and shares some, but not all characteristics of CPTs. The series of experiments described in this thesis contributes to the understanding of the role of the prefrontal cortex and cholinergic modulation in attentional performance; they also highlight differences between the two tasks in behaviour, brain functions and networks. Excitotoxic lesions of the medial prefrontal cortex (mPFC) and a range of cholinergic systemic pharmacology validated the role of the prefrontal cortex and cholinergic modulation in rCPT performance. A chemogenetic study also validated the role of the ascending cholinergic basal forebrain system in 5-CSRTT performance. These findings support 1. the idea of the relationship between cholinergic system activation and attentional performance to resemble an ‘inverted-U’ shaped function; 2. a double dissociation of mPFC sub-regions on attentional performance, in which the prelimbic cortex (PL) appears to play a role in rCPT performance, compared with a role of the anterior cingulate cortex (ACC) in 5-CSRTT performance; and 3. a role of ascending cholinergic projections from the basal forebrain to the ACC in 5-CSRTT performance. These findings also establish the development of a successful flanker distractor probe in rodents on the rCPT. This thesis concludes with an important comparison of the attentional and impulsivity measures in the rCPT compared to the 5-CSRTT, to help provide guidelines as to which task is most appropriate to use for particular research questions.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:744672 |
| Date | January 2018 |
| Creators | Fisher, Beth Mary |
| Contributors | Bussey, Tim |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.repository.cam.ac.uk/handle/1810/274607 |
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