CBF, BOLD, CBV and CMRO₂ FMRI at 500-Ms Temporal Resolution

Q. Shen, H. Ren, T. Q. Duong Yerkes Primate Research Center, Emory Unviersity, Atlanta, GA, United States Introduction The intricate neural-vascular coupling associated with changes in neural activity forms the basis for many modern neuroimaging modalities. However, the temporal dynamics of the stimulus-evoked CBF and CBV responses and the resulting BOLD signals remain poorly understood and somewhat controversial. In this study, we further investigated the CBF, BOLD, CBV and CMRO2 fMRI dynamics at high temporal resolution (500 ms) in a single setting. fMRI percent changes, onset times, time to peaks and post-stimulus undershoot were analyzed for the entire forepaw somatosensory cortices and for three operationally defined layers (Layer I-III, IV-V, and VI) within the forepaw somatosensory cortices. Although fMRI does not have sufficient spatial resolution to resolve different vascular compartments, the temporal latencies of the BOLD, CBF and CBV fMRI signals could shred lights on the fMRI signal sources and their spatial specificity.