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Abstract

Though functional MRI (fMRI) has been routinely used to map global brain function noninvasively, the direct and distinct vascular reflect of fMRI signal has seldom been identified from MRI images composed of large brain voxels. In contrast to conventional fMRI studies based on smoothened brain voxel clusters, we are seeing through the large voxel to directly decipher the contribution from distinct vascular components to fMRI signal. The individual arterioles and venules penetrating cortices were directly mapped based on the blood in-flow effect and fast T2* decay of the de-oxygenated blood. Distinct blood-oxygen level dependent (BOLD) and cerebral blood volume (CBV) fMRI signal was detected on individual venules and arterioles with 100ms sampling rate. This fast sampling rate allows us to identify the activity-evoked hemodynamic signal propagation through cerebrovasculature in the deep cortical layer of the somatosensory cortex. This technical improvement makes fMRI more suitable for mechanistic studies on neurovascular coupling in both normal and diseased states.