Neural Correlates of Spontaneous BOLD Fluctuations: A Simultaneous LFP-fMRI Investigation In The Non-human Primate

.............................................................................................................................. ii Acknowledgments .............................................................................................................. iv Table of Contents ............................................................................................................... vi List of Figures .................................................................................................................. viii List of Appendices ............................................................................................................... x List of Abbreviations and Symbols .................................................................................... xi 1 Introduction ..................................................................................................................... 1 1.1 Resting-state functional Magnetic Resonance Imaging in the Clinical Realm ....... 1 1.2 How fMRI Works .................................................................................................... 2 1.3 Resting-State fMRI .................................................................................................. 6 1.3.1 Resting-State Functional Connectivity ........................................................ 7 1.3.2 Structural vs Functional Connectivity ......................................................... 8 1.4 fMRI-based Approaches for Identifying Spatial Patterns ....................................... 9 1.5 Contribution of Electrophysiology to fMRI .......................................................... 10 1.6 HRF Models for fMRI Data Analysis ................................................................... 11 1.7 Neural Basis of BOLD fMRI ................................................................................ 12 1.7.1 Single-Unit Recordings ............................................................................. 14 1.7.2 Multi-Unit Recordings ............................................................................... 14 1.7.3 Local Field Potentials ................................................................................ 15 1.7.4 BOLD Signal Is A Reflection of Synaptic Activity .................................. 16 1.7.5 How to Study Local Field Potentials ......................................................... 18 1.8 Microcircuitry Differences across the Cortex ....................................................... 18 1.9 Human and Monkey Brain Similarities ................................................................. 20 1.10 Neural Correlates of Resting-state BOLD fMRI .................................................. 21 vii 1.11 Rationale and Hypothesis of the Current Study ................................................... 24 2 Methods ........................................................................................................................ 26 2.1 Animal Implantation .............................................................................................. 26 2.2 Animal Preparation ................................................................................................ 28 2.3 MRI Acquisition .................................................................................................... 29 2.4 LFP Acquisition ..................................................................................................... 30 2.5 Image Preprocessing .............................................................................................. 32 2.6 BOLD-fMRI Analysis ........................................................................................... 33 2.7 LFP Analysis ......................................................................................................... 35 3 Results ........................................................................................................................... 38 3.1 BOLD Seed-Based Analysis ................................................................................. 38 3.2 LFP-BOLD Correlation ......................................................................................... 40 3.2.1 LFP-BOLD Correlation within Averaged BOLD Networks ..................... 40 3.2.2 LFP-BOLD Correlation within Individual ROIs ....................................... 43 3.3 Effect of HRF Variation on LFP-BOLD Correlation ............................................ 45 3.4 Electrophysiological BLP Regression Analysis .................................................... 53 4 Discussion and Conclusions ......................................................................................... 58 4.1 LFP-BOLD Correlation ......................................................................................... 58 4.2 Effect of HRF Variation on LFP-BOLD Correlation ............................................ 61 4.3 Resting-State fMRI Confounds ............................................................................. 62 4.4 Effect of Anesthetics on Brain Functional Architecture ....................................... 64 4.5 Conclusions ........................................................................................................... 64 References ......................................................................................................................... 67 Appendix A ....................................................................................................................... 85 Curriculum Vitae ............................................................................................................... 86