Mapping functionally related regions of brain with functional connectivity MR imaging.

TLDR

Functional connectivity MRI (fcMRI) detects synchronous low‑frequency blood‑flow fluctuations during rest, while task‑based fMRI maps regions whose blood flow increases in synchrony with task performance. The study aimed to test whether resting‑state fcMRI maps, derived from low‑frequency synchrony, can identify the same brain regions that are activated during sensorimotor, visual, language, and auditory tasks. Four volunteers underwent simultaneous task‑activation fMRI and resting‑state fcMRI; a seed ROI from maximal task activation was correlated with all voxels, decomposed into frequency components, and the resulting fcMRI maps were compared to task fMRI maps. The fcMRI maps produced clusters that closely matched task‑fMRI activations, with dominant frequencies below 0.1 Hz, demonstrating that synchronous slow fluctuations can identify functionally related regions across sensorimotor, language, and visual cortices.

Abstract

In subjects who are performing no prescribed cognitive task, functional connectivity mapped with MR imaging (fcMRI) shows regions with synchronous fluctuations of cerebral blood flow. When specific tasks are performed, functional MR imaging (fMRI) can map locations in which regional cerebral blood flow increases synchronously with the performance of the task. We tested the hypothesis that fcMRI maps, based on the synchrony of low-frequency blood flow fluctuations, identify brain regions that show activation on fMRI maps of sensorimotor, visual, language, and auditory tasks.In four volunteers, task-activation fMRI and functional connectivity (resting-state) fcMRI data were acquired. A small region of interest (in an area that showed maximal task activation) was chosen, and the correlation coefficient of the corresponding resting-state signal with the signal of all other voxels in the resting data set was calculated. The correlation coefficient was decomposed into frequency components and its distribution determined for each fcMRI map. The fcMRI maps were compared with the fMRI maps.For each task, fcMRI maps based on one to four seed voxel(s) produced clusters of voxels in regions of eloquent cortex. For each fMRI map a closely corresponding fcMRI map was obtained. The frequencies that predominated in the cross-correlation coefficients for the functionally related regions were below 0.1 Hz.Functionally related brain regions can be identified by means of their synchronous slow fluctuations in signal intensity. Such blood flow synchrony can be detected in sensorimotor areas, expressive and receptive language regions, and the visual cortex by fcMRI. Regions identified by the slow synchronous fluctuations are similar to those activated by motor, language, or visual tasks.