Is There a Different Type of MR-Contrast in the Early Phase of Functional Activation?
Conventional functional MR is based on the BOLD-mechanism (1), according to which local hyperperfusion following cortical activation leads to an increase in the oxyhemoglobin concentration of the activated areas, which can be observed by susceptibility sensitive MR imaging techniques such as echo planar imaging (2) or gradient echo imaging with long echo times (3).
KeywordsInitial Drop Intrinsic Signal Stimulation Cycle Laxation Time Amplitude Effect
Unable to display preview. Download preview PDF.
- 2.K.K. Kwong, J.W. Belliveau, D.A. Chesler, I.E. Goldberg, R.M. Weisskoff, B.P. Poncelet, D.N. Kennedy, B.E. Hoppel, M.S. Cohen, R. Turner, H.M. Cheng, T.J. Brady and B.R. Rosen: Dynamic magnetic resonance imaging of human brain activity during primary sensory stimulation. Proc. Natl. Acad. Sci USA 89 (1992) 5675–5679.ADSCrossRefGoogle Scholar
- 6.R.D. Frostig, E.E. Lieke, D.Y. Ts’o, A. Grinvald. Cortical functional architecture and local coupling between neuronal activity and the microcirculation revealed by in vivo high-resolution optical imaging of intrinsic signals. Proc. Natl. Acad. Sci. USA 87, 6082–6086 (1990).ADSCrossRefGoogle Scholar
- 11.L.B. Cohen. Changes in neuron structure during action potential propagation and synaptic transmission. Physiol. Rev. 53, 373–418 (1973).Google Scholar
- 12.R.S. Menon, X. Hu, P. Andersen, K. Ugurbil, S. Ogawa. Cerebral Oxy/Deoxy Hemoglobin Changes During Neural Activation: MRI Timecourse Correlates to Optical Reflectance Measurements. Proc.2nd Meeting Soc.of Magnetic Resonance, San Francisco, p.68 (1994).Google Scholar