Contrasting Evolutionary Patterns of Functional Connectivity in Sensorimotor and Cognitive Regions after Stroke

Abstract

The human brain is a highly connected and integrated system. Local stroke lesions can evoke reorganization in multiple functional networks. However, the temporally-evolving patterns in different functional networks after stroke remain unclear. Here, we aimed to investigate the dynamic evolutionary patterns of functional connectivity density (FCD) and strength (FCS) of the brain after subcortical stroke involving in the motor pathways. Eight male patients with left subcortical infarctions were longitudinally examined at five time points within a year. Voxel-wise FCD analysis was used to identify brain regions with significant dynamic changes. The temporally-evolving patterns in FCD and FCS in these regions were analyzed by a mixed-effects model. Associations between these measures and clinical variables were also explored in stroke patients. Voxel-wise analysis revealed dynamic FCD changes only in the sensorimotor and cognitive regions after stroke. FCD and FCS in the sensorimotor regions decreased initially, as compared to controls, remaining at lower levels for months, and finally returned to normal levels. In contrast, FCD and FCS in the cognitive regions increased initially, remaining at higher levels for months, and finally returned to normal levels. Most of these measures were correlated with patients’ motor scores. These findings suggest a network-specific dynamic functional reorganization after stroke. Besides the sensorimotor regions, the spared cognitive regions may also play an important role in stroke recovery.

Homotopic Connectivity in Early Pontine Infarction Predicts Late Motor Recovery

“…Actually, patterns of FC changes in cognitive areas presented in our work were consistent with previous longitudinal studies. Enhanced FC alterations associated with cognitive function could appear immediately after stroke onset and remain at high levels for weeks or months, even in patients with recovered motor function ( 8 , 36 ). These changes may indicate a neural mechanism of long-term cognitive compensation for motor dysfunction.…”

Altered intra‐ and inter‐network functional coupling of resting‐state networks associated with motor dysfunction in stroke

“…Therefore, a growing number of studies are employing this technique to map the spatio‐temporal covariance structure of networks of spontaneous brain activity to investigate the reorganization of motor function following stroke (Golestani, Tymchuk, Demchuk, Goodyear, & Group, ; Wang et al, ; Yin et al, ). Many resting‐state studies have accordingly shown the altered functional connectivity of both sensorimotor and higher order cognitive control regions (Liu, Tian, Qin, Li, & Yu, ; Park et al, ; Zhao et al, ). In addition, many previous studies that described tasks and seed‐based FC engaged more than basic sensorimotor processes, such as the abnormal activation or FC in temporal and occipital regions (Park et al, ; Ward et al, ; Zhao et al, ).…”

Functional network connectivity is altered in patients with upper limb somatosensory impairments in the acute phase post stroke: A cross-sectional study

“…In literature, decreased interhemispheric functional connectivity is described in rats and humans after stroke to be associated with impaired sensorimotor function [ 6 , 47 , 50 , 52 ], and our study adds to this concept for the domain of arm and hand somatosensory deficits. Carter et al [ 48 ] presented an association between a disruption in interhemispheric functional connectivity of the sensorimotor network and upper extremity motor impairments in the acute phase post stroke.…”

“…Our results extend these prior findings by showing that already at one week after stroke, the extent of altered (reduced) inter-hemispheric functional connectivity of the somatosensory network is associated with more severe impairments in somatosensory function. Together, these observations highlight the behavioural relevance of the integrity of resting-state inter-hemispheric connectivity for both motor and somatosensory function and therefore provide further support to the notion that assessments of restorations/normalizations of these altered interhemispheric connectivity patterns may form a reliable index for evaluating the effectiveness of rehabilitation therapies at the neural level [ 6 , 17 , 52 ].…”