Rosen is the senior author on two seminal papers in the development of
functional MRI. He was one of John (Jack) Belliveau's thesis advisers when Belliveau – a Harvard graduate student working in the NMR Center (now the Martinos Center) at
Massachusetts General Hospital – performed his early experiments using MRI to reveal regional activity in the brain. Using an MR technique he had developed to track blood flow ("dynamic susceptibility contrast") he imaged the visual cortex of volunteers during periods of both rest and activation. By subtracting one image from the other, he then demonstrated differences in MR signal between the two.
Science recognized the significance of this work as the first demonstration of functional MRI in the human brain. It published Belliveau's report in November 1991 – with Rosen as the senior author – and featured one of his images on the cover. The study opened the door to functional imaging the brain with MRI, but because the approach required the use of an intravenous
contrast agent it was not suitable for wide application in humans. To address this limitation,
Kenneth Kwong, a postdoctoral fellow in the NMR Center, developed a means to measure endogenous signals based on blood oxygenation using gradient echo imaging. He successfully demonstrated the technique in May 1991 and a report of the findings was published in 1992 in the
Proceedings of the National Academy of Sciences of the United States of America. == Research Activities ==