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Objective:To explore the characteristics of functional connectivity (FC) and regional spontaneous brain activity in patients in a minimally-conscious state (MCS).Methods:Resting-state functional near-infrared spectroscopy (rs-fNIRS) was used. Ten minimally-conscious patients were studied along with 12 healthy counterparts as healthy controls (HC). Five minutes of rs-fNIRS data were recorded from each subject and FC and the fractional amplitude of low-frequency fluctuations (fALFFs) of 53 channels were computed using the NIRS-KIT toolbox. The results were compared between the two groups.Results:Compared with the HC group, a significant decrease was observed in the average FC strength of seventeen channel pairs after false discovery rate (FDR) correction. Most were in the right and left frontal pole, as well as the dorsolateral prefrontal lobe. Compared with the HC group, the average fALFF values of Broca′s area (channel 2), the premotor cortex and the supplementary motor cortex (channels 4, 10, and 40), the dorsolateral prefrontal lobe (channels 6, 11, 25, 39), the eye motor area of the frontal lobe (channel 12) and the frontal pole (channels 23, 27, 36) were significantly greater in the MCS group. The fluctuations of the frontal pole (channel 19) were significantly less (after FDR correction).Conclusion:In an MCS spontaneous neural activity is over-active in the prefrontal lobe and some speech- and motor-related brain regions, and coordination of the internal prefrontal functional network is disordered.
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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.
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Objective:To compare the effect of age and gender on mastication efficiency between healthy volunteers and dysphagic stroke survivors and to document any correlation of mastication efficiency with mandible movements.Methods:Thirty-two stroke survivors with dysphagia and 84 healthy volunteers were asked to chew two-color gum. Their chewing efficiency was indicated by the degree of color mixing after chewing (SDHue). The SDHue value was evaluated using ViewGum software. The healthy volunteers were further divided into an age 20-40 years group, a 41-60 years group and an over-60 group. The SDHue values were compared among the 3 groups. The SDHue values were correlated with clinical mandibule movement scores.Results:Among the healthy volunteers, those older than 60 years had significantly higher SDHue values on average than those between 20 and 40 years. However, no significant gender difference was observed. The dysphagic stroke survivors had, on average, significantly higher SDHue results than the healthy volunteers, and those results were positively correlated with their mandible movement scores.Conclusions:Mastication efficiency tends to be age-related but not gender-related. Among those with post-stroke dysphagia mandible movement is positively correlated with mastication efficiency.