R.Allen Waggoner1, Keiji Tanaka1, Kang Cheng1,2
1Laboratory for Cognitive Brain
Mapping, RIKEN-BSI, Wako-shi,
Recent DfMRI studies preformed at 3T have observed an increase in the fractional BOLD signal change with increasing b value during functional stimulation. The origin of this effect remains controversial with both cell swelling and vascular sources being offered as explanations. If this effect is truly due to cell swelling, increasing the static magnetic field will not alter the effect. We present DfMRI results obtained at 4T which shows a constant BOLD signal change with increasing b value. This result is consistent with a vascular source for a varying DfMRI response with diffusion weighting seen at 3T.