Intrinsic signal changes accompanying sensory stimulation: functional brain mapping with magnetic resonance imaging.
We report that visual stimulation produces an easily detectable (5-20%) transient increase in the intensity of water proton magnetic resonance signals in human primary visual cortex in gradient echo images at 4-T magnetic-field strength. The observed changes predominantly occur in areas containing gray matter and can be used to produce high-spatial-resolution functional brain maps in humans. Reducing the image-acquisition echo time from 40 msec to 8 msec reduces the amplitude of the fractional signal change, suggesting that it is produced by a change in apparent transverse relaxation time T*2. The amplitude, sign, and echo-time dependence of these intrinsic signal changes are consistent with the idea that neural activation increases regional cerebral blood flow and concomitantly increases venous-blood oxygenation.
Ogawa
S
S
Biological Computation Research Department, AT&T Bell Laboratories, Murray Hill, NJ 07974.
Tank
D W
DW
Menon
R
R
Ellermann
J M
JM
Kim
S G
SG
Merkle
H
H
Ugurbil
K
K
D001923:Brain Chemistry; D001931:Brain Mapping; D006801:Humans; D008027:Light; D008279:Magnetic Resonance Imaging; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D014867:Water / Q000737:chemistry
D014867:Water