Direct and fast detection of neuronal activation in the human brain with diffusion MRI.
Using MRI, we found that a slowly diffusing water pool was expanding (1.7 +/- 0.3%) upon activation on the human visual cortex at the detriment of a faster diffusing pool. The time course of this water phase transition preceded the activation-triggered vascular response detected by usual functional MRI by several seconds. The observed changes in water diffusion likely reflect early biophysical events that take place in the activated cells, such as cell swelling and membrane expansion. Although the exact mechanisms remain to clarify, access to such an early and direct physiological marker of cortical activation with MRI will provide opportunities for functional neuroimaging of the human brain.
Le Bihan
Denis
D
Human Brain Research Center, Kyoto University Graduate School of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan. lebihan@shfj.cea.fr
Urayama
Shin-ichi
S
Aso
Toshihiko
T
Hanakawa
Takashi
T
Fukuyama
Hidenao
H
D000328:Adult; D001703:Biophysics / Q000379:methods; D001921:Brain / Q000033:anatomy & histology* / Q000473:pathology*; D001931:Brain Mapping; D002462:Cell Membrane / Q000378:metabolism; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D015233:Models, Statistical; D009474:Neurons / Q000378:metabolism*; D013997:Time Factors; D014793:Visual Cortex