Laminar specificity of the SE-fMRI signal in monkey striate visual cortex
Goense J, Logothetis N
Max-Planck Institute for Biological Cybernetics
To relate fMRI signals to the underlying neural events, it is necessary to achieve a spatial resolution and specificity that permits visualization of the cortical functional units, e.g. cortical columns or laminae. Because the resolution of GE-fMRI is determined by intracortical veins and therefore limited, we used SE-fMRI, which is weighted towards capillaries, to obtain specific BOLD responses. SE-EPI however is also sensitive to the venous fraction, potentially limiting spatial resolution. By decreasing the EPI acquisition window, we obtained highly specific functional activation. Activation was predominantly located in layer IV, while activation around surface vessels varied with acquisition window length.