The topology of resting-state functional networks in the brain after an ischemic stroke / 中华物理医学与康复杂志

ABSTRACT

Objective:To explore any changes in the topology of the brain′s resting-state functional networks after an ischemic stroke causing cognitive impairment (iPSCI) and their relationship with the impairment.Methods:Twenty-one patients with impaired cognition after a stroke were recruited into an iPSCI group, and 21 healthy counterparts matched in gender, age and the education level formed the control (HC) group. Three-dimensional T1-weighted anatomical images and resting state functional magnetic resonance images of all of the subjects were collected and any differences in brain network topology were analyzed using graph theory. The degree of centrality (DC), between centrality (BC) and the global topological properties of each brain region were compared using independent-sample t-tests. Spearman correlation coefficients were computed to analyze the significance of any correlation between topology differences and Montreal Cognitive Assessment Scale (MoCA) or Mini-Mental Status Examination (MMSE) scores.Results:Compared with the HC group, a significant DC increase was observed in the orbital part of the right of middle frontal gyrus (ORBmid.R), the right hippocampus (HIP.R), and the right thalamus (THA.R). There was a significant decrease in the left Rolandic operculum (ROL.L), the left postcentral gyrus (PoCG.L), the left supramarginal gyrus (SMG.L), the left angular gyrus (ANG.L), the left and right caudate nucleus (CAU.L and CAU.R), the putamen of the left lenticular nucleus (PUT.L), the left Heschl gyrus (HES.L), the left superior temporal gyrus (STG.L), and the temporal pole of the left superior temporal gyrus (TPOsup.L). Compared with the HC group, the brain regions of the iPSCI group in which the BC had increased significantly were the orbital part of the left middle frontal gyrus (ORBmid.L), the left cuneus (CUN.L), and the right precuneus (PCUN.R). DC was significantly decreased in the left caudate nucleus (CAU.L), the left temporal pole of the superior temporal gyrus (TPOsup.L), and the left of inferior temporal gyrus (ITG.L). Compared with the HC group, the area under the receiver operating curve (AUC) of the shortest path length (Lp) and the normalized Lp (λ) of the iPSCI group increased significantly, and the AUC of the normalized clustering coefficient (γ) and small-worldness (σ) decreased significantly. The DCs of the ROL.L, PoCG.L, CAU.L, HES.L, STG.L and TPOsup.L regions showed moderate positive correlation with the MoCA and MMSE scores ( r>0.4), as did the BC of the CAU.L and TPOsup.L regions ( r>0.4). Conclusions:Cognitive impairment is mainly associated with decreased nodal properties in the brain regions related to language and in the caudate nucleus. The topology of the frontal lobe, hippocampus, thalamus, striatum and default networks may self-repair after an iPSCI. The brain′s functional network after an iPSCI still has small-world properties, but with low efficiency and high cost.