Diffusion
fMRI (DfMRI) has been shown to reflect neuronal activation more directly than
BOLD fMRI, showing neuronal responses even when neurovascular coupling is
abolished. We compared resting state ADC and BOLD fMRI time courses under
different anesthesia conditions. While BOLD fMRI showed a widespread signal increase
with isofluorane and a decrease with medetomidine, the ADC increased
significantly with both agents in specific regions, notably in the wakefulness/sleep network. The
amount of ADC increase was correlated with the dose of anesthetic agent, suggesting the
suitability of DfMRI to investigate brain resting state or pharmacological
challenges quantitatively and without vascular confounding effects.
