St Andrews Research Repository

St Andrews University Home
View Item 
  •   St Andrews Research Repository
  • Psychology & Neuroscience (School of)
  • Psychology & Neuroscience
  • Psychology & Neuroscience Theses
  • View Item
  •   St Andrews Research Repository
  • Psychology & Neuroscience (School of)
  • Psychology & Neuroscience
  • Psychology & Neuroscience Theses
  • View Item
  •   St Andrews Research Repository
  • Psychology & Neuroscience (School of)
  • Psychology & Neuroscience
  • Psychology & Neuroscience Theses
  • View Item
  • Login
JavaScript is disabled for your browser. Some features of this site may not work without it.

Linking actions to outcomes : the role of the posterior pedunculopontine tegmental nucleus in instrumental learning

Thumbnail
View/Open
DuncanMacLarenPhDThesis.pdf (6.129Mb)
Date
01/11/2012
Author
MacLaren, Duncan A. A.
Supervisor
Winn, Philip
Funder
Wellcome Trust
University of St Andrews. School of Psychology
Keywords
Pedunculopontine
Learning
Action-outcome
Cholinergic
Dtx-UII
Basal ganglia
Metadata
Show full item record
Altmetrics Handle Statistics
Abstract
Located in the mesopontine tegmentum, the pedunculopontine tegmental nucleus (PPTg) is comprised principally of glutamatergic, cholinergic and GABAergic neurons. In addition to being fully integrated into basal ganglia, PPTg projects to thalamus and motor output sites in the brainstem. Previous studies have shown a range of behavioural changes after PPTg manipulation. Prominent amongst these is an apparent deficit in the ability to learn the consequences of actions. PPTg is divisible into a posterior component (pPPTg) in receipt of rapid polymodal sensory input and projecting into VTA/SNc dopamine neurons and an anterior component (aPPTg) in receipt of basal ganglia outflow and projecting into SNc and lower brainstem structures. The research described here assesses the role of the pPPTg in instrumental learning. Using a contingency degradation paradigm, it was shown that inactivation of the pPPTg (by muscimol microinfusion) specifically blocked the updating of associations between actions and outcomes, without the affecting the ability to re-execute previously learned instrumental actions. Selective bilateral destruction of pPPTg cholinergic neurons (with the fusion toxin diphtheria toxin – urotensin II [Dtx-UII]) resulted in >90% loss of pPPTg cholinergic neurons. These lesions produced no detectable changes on any measured aspect of an instrumental learning task consisting of various fixed and variable ratio schedules of reinforcement and extinction. Subsequent experiments found that the same selective cholinergic pPPTg lesions also produced no changes in the locomotor response to nicotine or rate of nicotine sensitisation. These results are the first to demonstrate a brainstem role in action-outcome learning. Results support the view that PPTg performs a ‘first pass’ analysis on incoming sensory data and interfaces salient aspects of this with appropriate basal ganglia and brainstem circuitry, with glutamatergic pPPTg projections sending an essential signal and cholinergic projections performing as part of a wider modulatory system.
Type
Thesis, PhD Doctor of Philosophy
Collections
  • Psychology & Neuroscience Theses
URI
http://hdl.handle.net/10023/3183

Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Advanced Search

Browse

All of RepositoryCommunities & CollectionsBy Issue DateNamesTitlesSubjectsClassificationTypeFunderThis CollectionBy Issue DateNamesTitlesSubjectsClassificationTypeFunder

My Account

Login

Open Access

To find out how you can benefit from open access to research, see our library web pages and Open Access blog. For open access help contact: openaccess@st-andrews.ac.uk.

Accessibility

Read our Accessibility statement.

How to submit research papers

The full text of research papers can be submitted to the repository via Pure, the University's research information system. For help see our guide: How to deposit in Pure.

Electronic thesis deposit

Help with deposit.

Repository help

For repository help contact: Digital-Repository@st-andrews.ac.uk.

Give Feedback

Cookie policy

This site may use cookies. Please see Terms and Conditions.

Usage statistics

COUNTER-compliant statistics on downloads from the repository are available from the IRUS-UK Service. Contact us for information.

© University of St Andrews Library

University of St Andrews is a charity registered in Scotland, No SC013532.

  • Facebook
  • Twitter