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Abstract

Functional MR imaging in monkeys promises a bridge between brain research in humans and the large body of systems neuroscience work in animals. Prerequisite for successful interspecies-comparisons, however, is a profound understanding of the neural events underlying the hemodynamic responses. Combined physiology and neuroimaging experiments made the first step in this direction by examining directly the relationship of cell activity to the BOLD signal [1]. The tight coupling between regional neural activity and blood flow, however, suggests that perfusion-based MRI may improve even further the electrophysiological investigations of the neurovascular coupling, as perfusion imaging measures cerebral blood flow (CBF) directly at the capillary level. Moreover, CBF changes and interleaved-acquired BOLD data can be
combined to compute changes in oxygen consumption rate.
Obtaining functional CBF maps with high spatial resolution is challenging, because the CBF signal is intrinsically low and the signal-to-noise ratio is critical. Here we report the first high-resolution CBF maps that were obtained with voxel sizes as small as 0.5 x 0.5 x 3 mm3 in the Macaca mulatta. High sensitivity was achieved by using a high magnetic field scanner and custom-made RF combination-coil designs. CBF maps and functional CBF data were acquired and compared with BOLD data in the macaque primary visual
cortex.