From BOLD Contrast to Imaging Human Brain Function

Abstract

The authors of this chapter are together responsible for one of the efforts that introduced functional brain imaging with magnetic resonance (fMRI) in experiments that were carried out in the Center for Magnetic Resonance Research (CMRR), University of Minnesota. This effort came about because of the early experiments started by one of us (S. Ogawa) in the rodent brain with a small animal magnetic resonance (MR) instrument, aimed at uncovering signal components that could reflect the physiological condition of the brain, leading to the introduction of the blood oxygenation level-dependent (BOLD) contrast. This effort coincided with a programmatic development that the other of us (K. Ugurbil) was pursuing at the University of Minnesota at about the same time that culminated in the establishment of a high magnetic field (4 Tesla) instrument in ~1990 for MR imaging and spectroscopy studies in humans. Concepts of BOLD contrast linking MR image intensities to deoxyhemoglobin content was then applied in the human brain at 4 Tesla in CMRR, leading to one of the first demonstrations of functional imaging in the human brain. The experiments in Minnesota was carried out by a small team that included the direct participation of the two authors of this chapter; the effort was impeded quite a bit by the fact that 4 Tesla was a new platform and many sequences and hardware had to be developed in-house. We were, however, rewarded with high resolution functional images that that followed contours of the cortical ribbon and initiated the development of even higher magnetic fields for functional brain imaging.