The overall aim of this proposal is to establish the relationships between changes in BOLD signals obtained with functional magnetic resonance imaging (fMR) and changes in activity of neurons during the same cognitive measures, at the same sites, in the same subjects in human association cortex. The proposal utilizes a unique clinical opportunity, patients undergoing surgery for epilepsy with a technique where they are awake under local anesthesia for a portion of the operation. In that context we have previously recorded neuronal activity, both action potentials (AP) and overlying electroencephalogram (ECoG) from lateral temporal association cortex during recent verbal memory, finding that a substantial proportion of neurons changed the frequency of AP activity with that task. Both the fMR literature and our preliminary fMR data show fMR changes in lateral temporal cortex with recent memory measures. Having developed a recent verbal memory measure suitable for both fMR and intraoperative recording, we propose investigating the spatial and temporal relation between AP, local field potential (LFP), ECoG and fMR. Hypotheses to be tested include a closer relation between fMR and LFP than AP activity, based on findings reported from nonhuman studies, and specificity of fMR changes to sites with sustained patterns of AP activity during memory. These studies provide a unique window into how neural activity is reflected in changes in BOLD fMR during higher-level cognitive measures.
