Comparisons of Diffusion-Weighted and BOLD FMRI Signals in the Rat Somatosensory Cortex.

Tomokazu Tsurugizawa¹, Luisa Ciobanu¹, Denis Le Bihan¹

Diffusion-weighted functional MRI (DfMRI) has been shown to be sensitive to neural activation in the human brain. In this study, I compared the DfMRI (b=10, 250, and 1800) and BOLD signal changes in rat somatosensory cortex under hyperoxia without neuronal stimulation and forepaw electrical stimulation. The amplitude of the high b-value DfMRI (b=1800) signal was lower than those of BOLD signal during hyperoxia. During the forepaw stimulation, early return-to-baseline of the high b-value DfMRI response was observed compared to BOLD response. These results show that the BOLD and DfMRI signal point out different mechanisms.