Nyoman D. Kurniawan1, John Power2, Natalie Alexopoulos1, Donald J. Maillet3, Michael Vogel1, Ian M. Brereton1, David C. Reutens1
1Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia; 2Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia; 3Centre for Advanced Imaging, University of Queensland, Brisbane, Australia
Diffusion-weighted FMRI (DFMRI) was suggested to provide a more direct measurement of neuronal activation (Le Bihan et al., 2006). DFMRI methods are thought to reflect cell swelling and a reduction in extracellular space accompanying the influx of water and ions in active neurons. However, there is some evidence that in vivo DFMRI signals may be contaminated by haemodynamic/BOLD effects and thus put doubts about the significance and origin of the DFMRI signal. In this study, we aimed to verify the origin of DFMRI signal In Vitro using perfused brain slices free from haemodynamic effects. We found that DFMRI could detect activation signal in the absence of hemodynamic effects. In hippocampal slices, K+ stimulation induced changes in DFMRI signal with a similar spatial distribution and time course to that observed with fluorescence microscopy.