title: Comparison of diffusion-weighted fMRI and BOLD fMRI responses in a verbal working memory task.
abstract: Diffusion-weighted functional MRI (DfMRI) has been reported to have a different response pattern in the visual cortex than that of BOLD-fMRI. Especially, the DfMRI signal shows a constantly faster response at both onset and offset of the stimulus, suggesting that the DfMRI signal might be more directly linked to neuronal events than the hemodynamic response. However, because the DfMRI response also contains a residual sensitivity to BOLD this hypothesis has been challenged. Using a verbal working memory task we show that the DfMRI time-course features are preserved outside visual cortices, but also less liable to between-subject/between-regional variation than the BOLD response. The overall findings not only support the feasibility of DfMRI as an approach for functional brain imaging, but also strengthen the uniqueness of the DfMRI signal origin.
authors.affiliation: Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan. toaso@kuhp.kyoto-u.ac.jp
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Aso
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Urayama
authors.forename: Hidenao
authors.initials: H
authors.lastname: Fukuyama
authors.forename: Denis
authors.initials: D
authors.lastname: Le Bihan
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000502:physiology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008570:Memory, Short-Term / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013647:Task Performance and Analysis; D014706:Verbal Learning / Q000502:physiology*