Cognitive Roles of Anterior and Posterior Pedunculopontine Tegmentum Subregions

.............................................................................................................................. ii List of Abbreviations ......................................................................................................... iii Acknowledgments .............................................................................................................. iv Table of Contents ................................................................................................................ v List of Tables .................................................................................................................... vii List of Figures .................................................................................................................. viii Chapter 1 ............................................................................................................................. 1 1 The Pedunculopontine Tegmentum (PPT) ..................................................................... 1 1.1 Cell Biology ............................................................................................................ 1 1.2 Connectivity ............................................................................................................ 3 1.3 PPT Function .......................................................................................................... 7 1.4 Role in Thalamocortical Systems ........................................................................... 9 1.5 Role in Prepulse Inhibition ................................................................................... 10 1.6 Role in Striatal Reinforcement Learning .............................................................. 15 1.7 Objectives, Hypotheses, and Approach ................................................................ 22 Chapter 2 ........................................................................................................................... 23 2 Methods ........................................................................................................................ 23 2.1 Animals: Housing and Handling ........................................................................... 23 2.2 Stereotaxic Surgery ............................................................................................... 23 2.3 Behavioral Paradigms ........................................................................................... 25 2.4 Data Analysis ........................................................................................................ 27 2.5 Histology ............................................................................................................... 29 Chapter 3 ........................................................................................................................... 31 3 Results .......................................................................................................................... 31 vi 3.1 Lesion Analysis: Post-Surgery Spontaneous Turning Behavior and Histological Quantification ....................................................................................................... 31 3.2 Locomotor Data: Ambulatory Distance and Average Velocity ............................ 36 3.3 Startle Amplitude .................................................................................................. 40 3.4 Short-term Habituation ......................................................................................... 44 3.5 Long-term Habituation .......................................................................................... 46 3.6 Prepulse Inhibition ................................................................................................ 48 3.7 Morris Water Maze ............................................................................................... 51 Chapter 4 ........................................................................................................................... 56 4 Discussion .................................................................................................................... 56 4.1 Methodological Issues .......................................................................................... 56 4.2 Locomotor Activity ............................................................................................... 59 4.3 Amplitude and Habituation of the Startle Response ............................................. 59 4.4 Prepulse Inhibition of the Startle Response .......................................................... 61 4.5 Morris Water Maze ............................................................................................... 63 Chapter 5 ........................................................................................................................... 65 5 Conclusions .................................................................................................................. 65 References ......................................................................................................................... 66 Appendices ........................................................................................................................ 88 Curriculum Vitae .............................................................................................................. 90