The National University of Ireland An Examination of Hippocampal and Prefrontal Contributions to Spatial Learning and Memory using Immediate Early Gene Imaging Francesca R Farina, B.A. (Hons) Thesis submitted to the Department of Psychology, Faculty of Science and Engineering, in fulfilment of the requirements for the degree of Doctor of Philosophy, National University of Ireland, Maynooth October 2015 Head of Department: Dr Andrew Coogan Research Supervisor: Dr Seán Commins Table of Contents Table of Contents ......................................................................................................... ii Acknowledgements ...................................................................................................... v Publications and Published Abstracts from this Thesis .............................................. vi Summary .................................................................................................................... vii Chapter 1: Literature Review ................................................................ 1 1.1. Memory and navigation ................................................................................. 2 1.2. Theories of navigation ................................................................................... 2 1.3. The Morris water maze task........................................................................... 9 1.4. Brain regions involved in spatial learning and memory .............................. 11 1.4.1. Hippocampal formation ........................................................................ 12 1.4.2. Medial prefrontal cortex ........................................................................ 21 1.4.3. Connectivity between brain regions ...................................................... 27 1.5. Mechanisms underlying memory formation ................................................ 29 1.5.1. NMDA receptors ................................................................................... 32 1.5.2. AMPA and kainate receptors ................................................................ 35 1.6. Immediate Early Gene Imaging ................................................................... 37 1.6.1. Zif268 .................................................................................................... 38 1.6.2. c-Fos ...................................................................................................... 39 1.6.3. IEGs in learning and memory ............................................................... 40 1.7. Objectives of this thesis ............................................................................... 42 Chapter 2: General Methods ............................................................... 46 2.1. Subjects ........................................................................................................ 47 2.2. Morris water maze apparatus ....................................................................... 47 2.3. Morris water maze procedure ...................................................................... 49 2.3.1. Acquisition. ........................................................................................... 49 2.3.2. Recall..................................................................................................... 50 2.4. Drug administration ..................................................................................... 51 2.5. Tissue preservation ...................................................................................... 52 2.6. Immunohistochemistry ................................................................................ 52 2.7. Regions of interest ....................................................................................... 53 2.8. IEG quantification........................................................................................ 55 2.9. Statistical analysis ........................................................................................ 56 ii 2.10. Ethical considerations ................................................................................ 57 Chapter 3: An In-depth Behavioural Investigation of Cue Salience and Training Length in Allocentric Spatial Strategy Use ................. 58 3.1. Introduction .................................................................................................. 60 3.2. Experiment 1 ................................................................................................ 65 3.2.1. Method .................................................................................................. 65 3.2.2. Acquisition results ................................................................................. 68 3.2.3. Recall results ......................................................................................... 71 3.2.4. Discussion ............................................................................................. 75 3.3. Experiment 2 ................................................................................................ 77 3.3.1. Method .................................................................................................. 77 3.3.2. Acquisition results ................................................................................. 78 3.3.3. Recall results ......................................................................................... 80 3.3.4. Discussion ............................................................................................. 82 3.4. Experiment 3 ................................................................................................ 84 3.4.1. Method .................................................................................................. 84 3.4.2. Acquisition results ................................................................................. 85 3.4.3. Recall results ......................................................................................... 87 3.4.4. Discussion ............................................................................................. 91 3.5. Experiment 4 ................................................................................................ 93 3.5.1. Method .................................................................................................. 93 3.5.2. Acquisition results ................................................................................. 94 3.5.3. Recall results ......................................................................................... 96 3.5.4. Discussion ........................................................................................... 100 3.6. General discussion ..................................................................................... 102 Chapter 4: Examining the Effects of Glutamate Receptor Blockade on Spatial Learning and Immediate Early Gene Expression in the Hippocampus and Prefrontal Cortex ................................................ 108 4.1. Introduction ................................................................................................ 110 4.2. Experiment 1 .............................................................................................. 115 4.2.1. Method. ............................................................................................... 115 4.2.2. Results ................................................................................................. 117 4.2.3. Discussion ........................................................................................... 125 4.3. Experiment 2 .............................................................................................. 126 4.3.1. Method. ............................................................................................... 126 iii 4.3.2. Behavioural results. ............................................................................. 129 4.3.3. IEG results. .......................................................................................... 137 4.3.5. Discussion ........................................................................................... 148 4.4. General discussion ..................................................................................... 150 Chapter 5: Investigating the Neural Correlates of Spatial and Non- Spatial Memory Retrieval over Time Using Immediate Early Gene Imaging ................................................................................................. 155 5.1. Introduction ................................................................................................ 157 5.2. Experiment 1 .............................................................................................. 162 5.2.1. Method ................................................................................................ 162 5.2.2. Behavioural results .............................................................................. 167 5.2.3. IEG results. .......................................................................................... 175 5.2.4. Correlations with behaviour. ............................................................... 189 5.2.5. Discussion ........................................................................................... 192 5.3. Experiment 2 .............................................................................................. 198 5.3.1. Method ................................................................................................ 199 5.3.2. Behavioural results