Changes in Functional Connectivity of Default Mode Network with Auditory and Right Frontoparietal Networks in Post-Stroke Aphasia.

Changes in Functional Connectivity of Default Mode Network with Auditory and Right Frontoparietal Networks in Post-Stroke Aphasia.

Brain Connect. 2016 Aug 10;

Authors: Balaev V, Petruchevsky A, Martynova O

Abstract
To evaluate the influence of post-stroke aphasia on the functional association of widespread largescale neuronal networks, we analyzed functional connectivity between resting state brain networks (RSNs) in aphasic patients (N = 15) and in healthy volunteers (N = 17) of the same age using resting state fMRI. As a result, six RSNs were isolated and cross-correlation matrices were computed for their time courses. Aphasic patients showed decreased correlations between posterior part of the default mode (pDMN) and both auditory (AUD) and right frontoparietal (RFP) networks. Additionally, we calculated regions of interest based functional connectivity (ROI-FC), gray and white matter volumes in the ROIs overlapping with pDMN, AUD and RFP. ROI-FC analysis showed decreased FC between the right pars triangularis and both right middle frontal and right superior frontal gyri. The decreased pDMN-RFP connectivity in patients is likely to reflect changes in FC of these nodes. The lesion in the regions overlapping with pDMN and AUD networks lead to the significantly decreased pDMN-AUD connectivity. Our results suggest that abnormal functional connectivity in stroke patients may reflect the impairment of activity not only in the regions directly affected by stroke lesion in the left hemisphere, but also in the homotopic regions of the intact right hemisphere. The increase of gray and white matter volume in the right supramarginal gyrus, the functional hub of pDMN, AUD and RFP networks, correlated with less speech impairment. This increase might reflect a right hemisphere neuroplasticity process to compensate the impaired function of the homotopic region of LFP, pDMN and AUD in the left hemisphere. The presented results contribute to the hypothesized compensative role of the transfer of attention and executive functions from the damaged areas in the left hemisphere to the right homotopic areas, accompanied by more preserved language skills at the chronic stroke stage.

PMID: 27506234 [PubMed - as supplied by publisher]

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