However, recent developments in ultra-high field functional MRI (fMRI) make it feasible to examine the blood oxygen level dependent (BOLD) signal from cortical and subcortical regions with sub-millimeter resolution. With such resolution, cortical layers can be resolved reasonably, although some amount of partial voluming still exists. In addition, reliable methods have been developed to obtain cortical parcellation in the native space of individual subjects [8–12]. In the recent past, laminar fMRI studies have investigated the spatial sensitivity of high-field fMRI to the neuronal response at the sub-millimeter level [12–21], primarily using activation paradigms [13, 15, 18, 19, 21–23]. The sensitivity of laminar fMRI has enabled us to understand the columnar profile of cortical activation at a finer spatial scale in the cerebral cortex. However, these investigations were only in the context of laminar fMRI activation (not resting state) within specific brain regions for specific stimuli (example: primary visual cortex with visual stimuli). In addition, previous results were most often achieved with partial brain coverage at ultra-high fields (7 T for humans and > 7 T in case of animal studies) unlike whole brain coverage used in conventional resting state fMRI studies.
