Spatial specificity of CBV and BOLD fMRI in monkey striate cortex at 4.7T and 7T

Introduction High resolution fMRI allows us to determine more accurately the origins of the fMRI signal. This has shown that even at high field, the GE-BOLD signal has still a large vascular contribution [1]. Alternative methods like SEand monocrystalline iron oxide nanocolloid (MION)-based methods have been shown to be spatially more specific than conventional BOLD, and are able to reveal functional subunits in the cortex [2-6]. Here we compare the specificity of BOLD and CBV fMRI methods in the macaque; its striate cortex shows very obvious laminar structure in anatomical images, allowing accurate determination of the precise location of the fMRI activation.