Frequency-specific alterations of regional homogeneity in subcortical stroke patients with different outcomes in hand function

Abstract

Emerging evidence has suggested that abnormalities in regional spontaneous brain activity following stroke may be detected by intrinsic low-frequency oscillations (LFO) in resting-state functional MRI (R-fMRI). However, the relationship between hand function outcomes following stroke and local LFO synchronization in different frequency bands is poorly understood. In this study, we performed R-fMRI to examine the regional homogeneity (ReHo) at three different frequency bands (slow-5: .01-.027 Hz; slow-4: .027-.08 Hz; and typical band: .01-.1 Hz) in 26 stroke patients with completely paralyzed hands (CPH) and 26 matched patients with partially paralyzed hands (PPH). Compared to the PPH group, decreased ReHo in the bilateral cerebellum posterior lobes and the contralesional cerebellum anterior lobe was observed in the slow-5 band and the slow-4 band in the CPH group, respectively. The mean ReHo values in these regions were positively correlated with the Fugl-Meyer assessment (FMA) scores. In contrast, increased ReHo in the contralesional supplementary motor area and the contralesional superior temporal gyrus was observed in the slow-4 band and the slow-5 band, respectively. The mean ReHo values in these regions were negatively correlated with the FMA scores. Importantly, significant interactions were identified between the frequency bands and the subgroups of patients in the contralesional precentral gyrus and middle frontal gyrus. These findings indicate that frequency-dependent R-fMRI patterns may serve as potential biomarkers of the neural substrates associated with hand function outcomes following stroke.

Keywords: completely paralyzed hands; frequency-dependent; partially paralyzed hands; regional homogeneity; resting-state fMRI; stroke.

Figure 1

Lesion overlapped across the 26 PPH patients (the first raw), 26 CPH patients (the second raw) and total patients (the third raw). Color bar indicates the number of subjects having lesions in each voxel [Color figure can be viewed at http://wileyonlinelibrary.com]

Figure 2

Subgroup differences in ReHo in the full band (a) and specific frequency bands (b). Cold and hot colors indicate regions showing lower and higher ReHo in the CPH vs. PPH groups, respectively. Threshold of ReHo: p < .05 (corrected). SMA = supplementary motor area; PCu = precuneus; STG = superior temporal gyrus; CPL = cerebellum posterior lobe; CAL: cerebellum anterior lobe; L = left; R = right [Color figure can be viewed at http://wileyonlinelibrary.com]

Figure 3

Interaction effect between the frequency band (slow‐4 and slow‐5) and the group (CPH and PPH) on ReHo. Repeated‐measures anova (p < .05, corrected). T value bar is shown on the right. L = left; R = right; MFG = middle frontal gyrus; PreCG = precentral gyrus [Color figure can be viewed at http://wileyonlinelibrary.com]

Figure 4

Changes in ReHo between the patient group and the HC group in three different FBs. Hot colors indicate regions showing higher ReHo in the patient group than in the HC group. Threshold of ReHo: p < .05 (corrected). L = left; R = right [Color figure can be viewed at http://wileyonlinelibrary.com]

Figure 5

(a) Shows significant correlations between the mean ReHo with between‐subgroup differences and the FMA scores, (b) shows the corresponding brain regions, and (c) displays the between‐subgroup differences in the three different frequency bands. SMA_R = right supplementary motor area; STG_R = right superior temporal gyrus; CPL_R = right cerebellum posterior lobe; CPL_L = left cerebellum posterior lobe; CAL_R = right cerebellum anterior lobe; L = left; S = superior; P = posterior. ** Represents p value < .01 [Color figure can be viewed at http://wileyonlinelibrary.com]