| The spontaneous low frequency (<0.1 Hz) fluctuations in blood-oxygenation-level-dependent (BOLD) signal, as measured by resting state functional magnetic resonance imaging (rsMRI), has been suggested to reflect the brain's physiological electrical activity. However, the precise physiological oscillations underlying the spontaneous BOLD fluctuations are not understood, emphasizing the critical need for well-controlled animal models to investigate these phenomena. Conflicting data has demonstrated a positive correlation independently between BOLD fluctuations and both, the low frequency and high frequency local field potential (LFP) physiological oscillations. Due to methodological limitations, these studies failed to manipulate the LFP-BOLD correlation in a simultaneous manner impeding the identification of the major electrophysiological driving force of the BOLD oscillations. Here we modulated the low frequency LFP signal in the rat striatum by unilateral, intra-ventral tegmental area (VTA) injection of RS-alpha-amino-3-hydroxy-5-methyl-4-is-oxazolepropionic acid (AMPA), an AMPA receptor agonists, simultaneously with BOLD functional magnetic resonance imaging (fMRI) acquisition in a newly developed simultaneous acquisition animal model. The experiments discussed in this dissertation show that the low frequency delta rhythm LFP signal underlies the observed BOLD functional connectivity. |
