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. Swallowing dysfunction is intractable after acute stroke. Our understanding of the alterations in neural networks of patients with neurogenic dysphagia is still developing.
. The aim was to investigate cerebral cortical functional connectivity and subcortical structural connectivity related to swallowing in unilateral hemispheric stroke patients...
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The right inferior frontal cortex (rIFC) is frequently activated during executive control tasks. Whereas the function of the dorsal portion of rIFC, more precisely the inferior frontal junction (rIFJ), is convergingly assigned to the attention system, the functional key role of the ventral portion, i.e., the inferior frontal gyrus (rIFG), is hither...
Mirror visual feedback (MVF) has been shown to increase the excitability of the primary motor cortex (M1) during asynchronous bimanual movement. However, the functional networks underlying this process remain unclear. We recruited 16 healthy volunteers to perform asynchronous bimanual movement, that is, their left hand performed partial range of mo...
Citations
... After an acute stroke, dysphagia might occur due to loss of functional connectivity in the swallowing network. [3] Post-stroke dysphagia affects approximately 37% to 78% of patients [4,5]. Dysphagia is a condition in which food or liquid cannot be safely and effectively passed from the mouth to the stomach. ...
Stroke is the leading cause of death and disability among adults. The incidence of stroke per 100, 000 patient-years was 2875. As many as 37% to 78% of patients with acute strokes suffer dysphagia. Dysphagia can easily lead to inhalation pneumonia, dehydration, malnutrition, and other serious complications, affecting the quality of life of stroke patients and increasing their mortality. Effective prevention and treatment of post-stroke dysphagia are of great significance to improving the prognosis and quality of life of patients. Some studies have shown that Pharyngeal cavity electrical stimulation-assisted swallowing (PCES-assisted swallowing) has a positive effect on patients with post-stroke dysphagia. This study will evaluate the effects of PCES-assisted swallowing on post-stroke dysphagia, including swallowing function, withdrawal rate of nasal feeding tubes, duration of hospitalization, and so on. Randomized controlled trials (RCTs) of PCES-assisted swallowing in the treatment of post-stroke dysphagia were searched in eight databases, including Cochrane Library, Embase, PubMed, Web of Science, Chinese Biomedical Literature Database, VIP Information Resource System, CNKI, and Wanfang Medical Science. The retrieval time was from the database establishment to June 2022. Rayyan was used to screen the retrieved literature risk of bias for included studies and was calculated using ROB2.0. The RevMan 5.3 software was used for the meta-analysis with the standard mean difference (SMD) and 95% confidence interval (CI). The model type was a random effect model, The risk ratio (RR) was used as the effect size for the two categorical variables. The swallowing function scores, withdrawal rate of nasal feeding tubes, and Length of stay (LOS) of the intervention and control groups were extracted, and the results of the meta-analysis were presented using a forest plot. Six studies from 2010 to 2018 with a total of 341 people were included in the meta-analysis. All studies reported quantitative outcome measures for the severity of dysphagia, and some reported the withdrawal rate of nasal feeding tubes, LOS, and penetration-aspiration-scale (PAS). The overall swallowing function of the PCES group was better than that of the control group (SMD = − 0.20, 95%CI − 0.38 to − 0.03, P = 0.02). In terms of the severity of dysphagia, there was a statistically significant difference in the Dysphagia Severity Rating scale (DSRS) between the Pharyngeal cavity electrical stimulation (PCES) group and the control group (SMD = − 0.24, 95%CI − 0.48 to 0, P = 0.05). The PCES group nasal feeding withdrawal rate of nasal feeding tubes was higher than the control group (RR = 2.88, 95% CI 1.15 to 7.26, P = 0.02). There was no significant difference in the LOS between the PCES group and the control group (SMD = − 0.19, 95%CI − 0.44 to 0.07, P = 0.15). This systematic review and meta-analysis provide reasonably reliable evidence that PCES-assisted swallowing can improve nasogastric feeding swallowing function and the withdrawal rate of nasal feeding tubes in patients with post-stroke dysphagia. However, the evidence for reducing oral feeding, aspiration, and length of hospitalization stay is lacking, and further studies are needed.
... Such approaches might shed light on the hierarchical and functional implications of RSN circuits 49,50,52,53 . Recent results have highlighted the importance of white matter structural disconnections in the disruption of functional connectivity 53 , and this disruption has been linked to behavioural and cognitive dysfunction 54,55 . Therefore, being able to identify these RSN white matter "highways" would propel our understanding of disconnection symptoms, improve recovery prognostics, and inform preoperative brain surgery planning 56 . ...
Over the past two decades, the study of resting-state functional magnetic resonance imaging has revealed that functional connectivity within and between networks is linked to cognitive states and pathologies. However, the white matter connections supporting this connectivity remain only partially described. We developed a method to jointly map the white and grey matter contributing to each resting-state network (RSN). Using the Human Connectome Project, we generated an atlas of 30 RSNs. The method also highlighted the overlap between networks, which revealed that most of the brain’s white matter (89%) is shared between multiple RSNs, with 16% shared by at least 7 RSNs. These overlaps, especially the existence of regions shared by numerous networks, suggest that white matter lesions in these areas might strongly impact the communication within networks. We provide an atlas and an open-source software to explore the joint contribution of white and grey matter to RSNs and facilitate the study of the impact of white matter damage to these networks. In a first application of the software with clinical data, we were able to link stroke patients and impacted RSNs, showing that their symptoms aligned well with the estimated functions of the networks.
... Previous functional and structural connectivity analysis showed that dysphagia patients have disrupted functional connectivity in the sensorimotor-insula-putamen circuits, and structural disconnection in left-to-right supplementary motor areas and in the corticospinal tract [36]. Our study showed that more lesions in the four supratentorial areas: the inferior part of the precentral gyrus, lenticular nucleus, caudate head, and anterior insular cortex, are associated with longer duration to rate 7 points or above at FILS (Fig. 5). ...
This study aimed to identify the neuroanatomical predictors of oropharyngeal dysphagia and tube dependency in patients with supratentorial or infratentorial ischemic strokes. Patients with acute ischemic stroke were enrolled and were classified into 3 groups: right supratentorial (n = 61), left supratentorial (n = 89), and infratentorial stroke (n = 50). Dysphagia was evaluated by a modified water swallowing test and the Food Intake LEVEL Scale to evaluate oropharyngeal dysphagia and tube dependency, respectively. As two dysphagia parameters, we evaluated the durations from onset of stroke to (1) success in the modified water swallowing test and to (2) rating 7 points or above on the Food Intake LEVEL Scale: patients regained sufficient oral intake and were not tube-dependent. Voxel-based lesion-symptom mapping analysis was performed for a spatially normalized lesion map of magnetic resonance imaging to explore the anatomies that are associated with the two dysphagia parameters for each stroke group. The right precentral gyrus and parts of the internal capsule are associated with oropharyngeal dysphagia. The four supratentorial areas are associated with tube dependency. The dorsal upper medulla is associated with both oropharyngeal dysphagia and tube dependency. These results suggest that supratentorial stroke patients can be tube-dependent due to an impaired anticipatory phase of ingestion. The simultaneous damage in the four supratentorial areas: the inferior part of the precentral gyrus, lenticular nucleus, caudate head, and anterior insular cortex, predicts tube dependency. In contrast, infratentorial stroke patients can be tube-dependent due to oropharyngeal dysphagia caused by lesions in the dorsal upper medulla, damaging the swallowing-related nucleus.
... , postcentral gyrus(Li et al., 2009), supplementary motor areas(Zhang et al., 2022), cerebellar hemispheres(Malandraki et al., 2011;Li et al., 2014a;Jiao et al., 2020;Lin et al., 2021), cerebellar earth (Jiao et al., 2020), cingulate gyrus(Li et al., 2009;Momosaki et al., 2012;Long et al., 2019;Lin et al., 2021;Zhang et al., 2022), insula(Li et al., 2009(Li et al., , 2014aMalandraki et al., 2011;Long et al., 2019), thalamus(Zhang et al., 2022), caudate nucleus(Jiao et al., 2020), lentiform nucleus(Jiao et al., 2020;Zhang et al., 2022), superior frontal gyrus (Jiao et al., 2020), inferior frontal gyrus(Jiao et al., 2020;Zhang et al., 2022), visual centers, and primary auditory cortex(Long et al., 2019). Hypoactivation brain regions included precentral gyrus(Long et al., 2019;Lin et al., ...
... , postcentral gyrus(Li et al., 2009), supplementary motor areas(Zhang et al., 2022), cerebellar hemispheres(Malandraki et al., 2011;Li et al., 2014a;Jiao et al., 2020;Lin et al., 2021), cerebellar earth (Jiao et al., 2020), cingulate gyrus(Li et al., 2009;Momosaki et al., 2012;Long et al., 2019;Lin et al., 2021;Zhang et al., 2022), insula(Li et al., 2009(Li et al., , 2014aMalandraki et al., 2011;Long et al., 2019), thalamus(Zhang et al., 2022), caudate nucleus(Jiao et al., 2020), lentiform nucleus(Jiao et al., 2020;Zhang et al., 2022), superior frontal gyrus (Jiao et al., 2020), inferior frontal gyrus(Jiao et al., 2020;Zhang et al., 2022), visual centers, and primary auditory cortex(Long et al., 2019). Hypoactivation brain regions included precentral gyrus(Long et al., 2019;Lin et al., ...
... 2021), postcentral gyrus(Long et al., 2019;Lin et al., 2021), parietal lobe(Jiao et al., 2020;Lin et al., 2021;Li et al., 2022), occipital lobe(Lin et al., 2021), frontal lobe(Lin et al., 2021), insula(Li et al., 2009;Osawa et al., 2013;Long et al., 2019), cuneus(Osawa et al., 2013), cingulate gyrus(Li et al., 2009;Osawa et al., 2013), superior temporal gyrus(Lin et al., 2021;Li et al., 2022), middle temporal gyrus, inferior temporal gyrus(Jiao et al., 2020;Li et al., 2022), orbital gyrus (Jiao et al., 2020), hippocampus(Jiao et al., 2020), and thalamus(Li et al., 2009(Li et al., , 2014a(Li et al., ,b, 2022Momosaki et al., 2012;Lin et al., 2021), caudate nucleus(Lin et al., 2021), cisternal nucleus(Long et al., 2019), medulla oblongata(Lin et al., 2021), pons(Lin et al., 2021), and posterior cerebellar lobe ...
Objectives
Dysphagia is a major cause of stroke infection and death, and identification of structural and functional brain area changes associated with post-stroke dysphagia (PSD) can help in early screening and clinical intervention. Studies on PSD have reported numerous structural lesions and functional abnormalities in brain regions, and a systematic review is lacking. We aimed to integrate several neuroimaging studies to summarize the empirical evidence of neurological changes leading to PSD.
Methods
We conducted a systematic review of studies that used structural neuroimaging and functional neuroimaging approaches to explore structural and functional brain regions associated with swallowing after stroke, with additional evidence using a live activation likelihood estimation (ALE) approach.
Results
A total of 35 studies were included, including 20 studies with structural neuroimaging analysis, 14 studies with functional neuroimaging analysis and one study reporting results for both. The overall results suggest that structural lesions and functional abnormalities in the sensorimotor cortex, insula, cerebellum, cingulate gyrus, thalamus, basal ganglia, and associated white matter connections in individuals with stroke may contribute to dysphagia, and the ALE analysis provides additional evidence for structural lesions in the right lentiform nucleus and right thalamus and functional abnormalities in the left thalamus.
Conclusion
Our findings suggest that PSD is associated with neurological changes in brain regions such as sensorimotor cortex, insula, cerebellum, cingulate gyrus, thalamus, basal ganglia, and associated white matter connections. Adequate understanding of the mechanisms of neural changes in the post-stroke swallowing network may assist in clinical diagnosis and provide ideas for the development of new interventions in clinical practice.
... 60 Taken together, we speculate that the increased FC between ipsilesional IPL and M1 before intervention in our study could be part of a compensatory strategy that Enhanced FCs from the putamen to primary motor regions has been reported in patients with Parkinson's disease 64 and stroke. 65 A resting-state FC study revealed that the increased FC from the contralesional thalamus in patients with supratentorial stroke compared with healthy individuals and was correlated positively with motor improvement at 6-month follow-up. 66 Besides static FC analysis, the dynamic approach of FC analysis found that the variability of the connectivity between the ipsilesional sensorimotor cortex and putamen could discriminate patients with different levels of motor function. ...
Background
Motor imagery training (MIT) has been widely used to improve hemiplegic upper limb function in stroke rehabilitation. The effectiveness of MIT is associated with the functional neuroplasticity of the motor network. Currently, brain activation and connectivity changes related to the motor recovery process after MIT are not well understood.
Aim: We aimed to investigate the neural mechanisms of MIT in stroke rehabilitation through a longitudinal intervention study design with task‐based functional magnetic resonance imaging (fMRI) analysis.
Methods
We recruited 39 stroke patients with moderate to severe upper limb motor impairment and randomly assigned them to either the MIT or control groups. Patients in the MIT group received 4 weeks of MIT therapy plus conventional rehabilitation, while the control group only received conventional rehabilitation. The assessment of Fugl‐Meyer Upper Limb Scale (FM‐UL) and Barthel Index (BI), and fMRI scanning using a passive hand movement task were conducted on all patients before and after treatment. The changes in brain activation and functional connectivity (FC) were analyzed. Pearson's correlation analysis was conducted to evaluate the association between neural functional changes and motor improvement.
Results
The MIT group achieved higher improvements in FM‐UL and BI relative to the control group after the treatment. Passive movement of the affected hand evoked an abnormal bilateral activation pattern in both groups before intervention. A significant Group × Time interaction was found in the contralesional S1 and ipsilesional M1, showing a decrease of activation after intervention specifically in the MIT group, which was negatively correlated with the FM‐UL improvement. FC analysis of the ipsilesional M1 displayed the motor network reorganization within the ipsilesional hemisphere, which correlated with the motor score changes.
Conclusions
MIT could help decrease the compensatory activation at both hemispheres and reshape the FC within the ipsilesional hemisphere along with functional recovery in stroke patients.
... In patients with decreased FC between executive control, sensorimotor, and visuospatial networks, overall post-stroke functions have been found to be impaired (Almeida et al., 2017). Dysphagia in hemispheric stroke patients has been related to dysfunctional connectivity among large-scale brain networks in the sensorimotor-insula-putamen circuits and bilateral brain regions related to swallowing (Li et al., 2014). ...
Patients with infratentorial stroke (IS) exhibit more severe dysphagia and a higher risk of aspiration than patients with supratentorial stroke. Nevertheless, a large proportion of patients with IS regain swallowing function within 6 months; however, the neural mechanism for this recovery remains unclear. We aimed to investigate possible neuroplastic changes involved using functional magnetic resonance imaging (fMRI) and their relation to swallowing function. We assessed 21 patients with IS (mean age: 59.9 ± 11.1 years) exhibiting dysphagia in the subacute phase and 21 healthy controls (mean age: 57.1 ± 7.8 years). Patient evaluations were based on the functional oral intake scale (FOIS), videofluoroscopic swallow study (VFSS), and fMRI. Temporal swallowing measures and the penetration-aspiration scale (PAS) were obtained using VFSS. Whole-brain-medulla resting-state functional connectivity (rsFC) was calculated and compared between patients and healthy controls. The rsFCs were also correlated with functional measures within the patient group. In patients with IS, whole-brain-medulla rsFCs were significantly higher in the precuneus, the left and right precentral gyrus, and the right supplementary motor area compared to those in healthy controls (P < 0.001, family-wise error-corrected cluster-level P < 0.05). The rsFCs to the medulla for the left (r = -0.507, P = 0.027) and right side (r = -0.503, P = 0.028) precentral gyrus were negatively correlated with the PAS. The rsFC between the left (r = 0.470, P = 0.042) and right (r = 0.459, P = 0.048) precentral gyrus to the medulla was positively correlated with upper esophageal sphincter opening durations (UOD). In addition, PAS was also correlated with UOD (r = -0.638, P = 0.003) whereas the laryngeal closure duration was correlated with the hyoid bone movement duration (r = 0.550, P = 0.015). Patients with IS exhibited overall modulation of cortical-medulla connectivity during the subacute phase. Patients with higher connectivities showed better swallowing performance. These findings support that there is cortical involvement in swallowing regulation after IS and can aid in determining potential treatment targets for dysphagia.
... We now intended to investigate the relevance of the integrity of swallowingrelated callosal fibers for partially restituted swallowing function in the same group of patients. A recent review concerning the role of white matter in the neural control of swallowing (Alvar et al., 2021) identified two studies of the corpus callosum's role in swallowing impairment, both of which used only lesion mapping, with no individual quantification of white matter fibers (Li et al., 2014;Mourão et al., 2017). In a prior characterization of somatotopic fibers interconnecting the two hemispheres via the corpus callosum, we described a method that we believe allows for more exact quantification of these fibers, at least in the case of M1 (Domin and Lotze, 2019). ...
... This had to be done as there is a lack of data on somatosensory representation of the interconnecting callosal tracts involved in swallowing function itself. Prior studies investigating the role of the corpus callosum in swallowing impairment (Li et al., 2014;Mourão et al., 2017) only used lesion mapping, with no individual quantification of white matter fibers. Therefore, the elaborate approach used in this study is of great importance to the research field relating to biomarkers for dysphagia following brain damage (Alvar et al., 2021). ...
Sensorimotor representations of swallowing in pre- and postcentral gyri of both cerebral hemispheres are interconnected by callosal tracts. We were interested in (1) the callosal location of fibers interconnecting the precentral gyri (with the primary motor cortex; M1) and the postcentral gyri (with the primary somatosensory cortex; S1) relevant for swallowing, and (2) the importance of their integrity given the challenges of swallowing compliance after recovery of dysphagia following stroke. We investigated 17 patients who had almost recovered from dysphagia in the chronic stage following stroke and age-matched and gender-matched healthy controls. We assessed their swallowing compliance, investigating swallowing of a predefined bolus in one swallowing movement in response to a ‘go’ signal when in a lying position. A somatotopic representation of swallowing was mapped for the pre- and postcentral gyrus, and callosal tract location between these regions was compared to results for healthy participants. We applied multi-directional diffusion-weighted imaging of the brain in patients and matched controls to calculate fractional anisotropy (FA) as a tract integrity marker for M1/S1 callosal fibers. Firstly, interconnecting callosal tract maps were well spatially separated for M1 and S1, but were overlapped for somatotopic differentiation within M1 and S1 in healthy participants’ data (HCP: head/face representation; in house dataset: fMRI-swallowing representation in healthy volunteers). Secondly, the FA for both callosal tracts, connecting M1 and S1 swallowing representations, were decreased for patients when compared to healthy volunteers. Thirdly, integrity of callosal fibers interconnecting S1 swallowing representation sites was associated with effective swallowing compliance. We conclude that somatosensory interaction between hemispheres is important for effective swallowing in the case of a demanding task undertaken by stroke survivors with good swallowing outcome from dysphagia.
... Experimental evidence has demonstrated that white matter areas, including the pyramidal tract, internal capsule, corona radiata, superior longitudinal fasciculus, external capsule, and corpus callosum, are commonly implicated in swallowing control (Alvar et al., 2021). Moreover, cerebral ischaemia usually results in damage to white matter regions, especially the corpus callosum and the optic tract (Li et al., 2014a). Rodents subjected to cerebral hypoperfusion showed disintegration of the white matter tracts, as indicated by neuroinflammation, loss of oligodendrocytes, attenuation of myelin density, and structural derangement at the nodes of Ranvier (Choi et al., 2016). ...
... A systematic review revealed that white matter damage can be directly tied to swallowing deficits after ischemic stroke (Alvar et al., 2021). In a clinical study, Li et al. (2014a) found that the mean fractional anisotropy of the white matter tract was significantly reduced in patients with middle artery infarction and dysphagia. A retrospective analysis suggested that white matter lesion observed on brain magnetic resonance imaging scans was an independent factor affecting various swallowing parameters; specifically, prolonged oral transit time and penetration were predicted by the severity of the white matter lesion (Moon et al., 2017). ...
Background
Clinical and animal studies have shown that transcutaneous auricular vagus nerve stimulation (ta-VNS) exerts neuroprotection following cerebral ischemia. Studies have revealed that white matter damage after ischemia is related to swallowing defects, and the degree of white matter damage is related to the severity of dysphagia. However, the effect of ta-VNS on dysphagia symptoms and white matter damage in dysphagic animals after an ischemic stroke has not been investigated.
Methods
Middle cerebral artery occlusion (MCAO) rats were randomly divided into the sham, control and vagus nerve stimulation (VNS) group, which subsequently received ta-VNS for 3 weeks. The swallowing reflex was measured once weekly by electromyography (EMG). White matter remyelination, volume, angiogenesis and the inflammatory response in the white matter were assessed by electron microscopy, immunohistochemistry, stereology, enzyme-linked immunosorbent assay (ELISA) and Western blotting.
Results
ta-VNS significantly increased the number of swallows within 20 s and reduced the onset latency to the first swallow. ta-VNS significantly improved remyelination but did not alleviate white matter shrinkage after MCAO. Stereology revealed that ta-VNS significantly increased the density of capillaries and increased vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF2) expression in the white matter. ta-VNS significantly alleviated the increase inTLR4, MyD88, phosphorylated MAPK and NF-κB protein levels and suppressed the expression of the proinflammatory factors IL-1β and TNF-α.
Conclusion
These results indicated ta-VNS slightly improved dysphagia symptoms after ischemic stroke, possibly by increasing remyelination, inducing angiogenesis, and inhibiting the inflammatory response in the white matter of cerebral ischaemia model rats, implying that ta-VNS may be an effective therapeutic strategy for the treatment of dysphagia after ischemic stroke.
... Studies have shown that the cortical swallowing network involves several dispersed brain regions, including the primary sensorimotor cortex, insular lobe, frontal operculum, cingulate gyrus, temporal lobe, subcortical structure, cerebellum, etc. (16). These brain regions with tight functional connections regulate swallowing function together (17,18). In our study, compared with the nATM group, the ATM group had functional connectivity changes in the precentral gyrus, postcentral gyrus, frontal operculum, cingulate gyrus, temporal lobe, and cerebellum etc. ...
Objective
The independent component analysis (ICA) was applied to explore the correlation between clinical manifestation and the functional connectivity changes of the sensorimotor network (SMN) and left frontoparietal network (LFPN) in patients with acute thyrotoxic myopathy (ATM), which was expected to provide a functional imaging basis for the exploration of the pathophysiological mechanism of ATM.
Methods
13 ATM patients (ATM) and 12 non-ATM patients (nATM) who met the diagnostic and inclusion criteria were enrolled. Their resting-state brain function images were obtained with resting-state functional magnetic resonance imaging (rs-fMRI). GIFT software was used for independent component analysis to obtain the brain regions with SMN and LFPN changes. The correlation between the functional connectivity of these brain regions and clinical indicators was calculated.
Results
The SMN functional connectivity of ATM patients was increased at the posterior lobe of cerebellum, anterior lobe of cerebellum, right superior temporal gyrus, left cingulate gyrus, left precuneus, and left postcentral gyrus compared with that of nATM patients. However, it was decreased at the occipital lobe, right dorsolateral superior frontal gyrus, paracentral lobule, angular gyrus, and superior parietal gyrus (FDR correction, P<0.05). The LFPN functional connectivity of ATM patients was increased at the posterior lobe of cerebellum, middle temporal gyrus, inferior temporal gyrus, and right cingulate gyrus compared with that of nATM patients; but was decreased at frontal lobe, parahippocampal gyrus, precentral gyrus and postcentral gyrus (FDR correction, P<0.05) Correlation analysis results showed that the enhancement of SMN functional connection at right superior temporal gyrus was significantly negatively correlated with the free thyroxine level, and the decrease of SMN functional connectivity at occipital lobe was significantly positively correlated to the thyroid stimulating hormone level. The SMN and LFPN functional connectivity changes in other brain regions were not found to be significantly correlated with thyroid function parameters.
Conclusion
The bulbar paralysis (such as dysphagia, dysarthria) in ATM patients may be related to the functional connectivity changes of resting-state SMN and LFPN. The fMRI is expected to be one of the objective imaging indicators for the early clinical intervention of ATM patients.
... Such approaches might shed light on the hierarchical and functional implications of RSN circuits (46)(47)(48)(49). Recent results have highlighted the importance of white matter structural disconnections in the disruption of functional connectivity (49), and this disruption has been linked to behavioural and cognitive dysfunction (50,51). Therefore, being able to identify these RSN white matter "highways" would propel our understanding of disconnection symptoms, improve recovery prognostics, and inform preoperative brain surgery planning (52). ...
Over the past two decades, the study of resting-state functional magnetic resonance imaging (fMRI) has revealed the existence of multiple brain areas displaying synchronous functional blood oxygen level-dependent signals (BOLD)-resting-state networks (RSNs). The variation in functional connectivity between the different areas of a resting-state network or between multiple networks, have been extensively studied and linked to cognitive states and pathologies. However, the white matter connections supporting each network remain only partially described. In this work, we developed a data-driven method to systematically map the white and grey matter contributing to resting-state networks. Using the Human Connectome Project, we generated an atlas of 30 resting-state networks, each with two maps: white matter and grey matter. By integrating structural and functional neuroimaging data, this method builds an atlas that unlocks the joint anatomical exploration of white and grey matter to resting-state networks. The method also allows highlighting the overlap between networks, which revealed that most (89%) of the brain's white matter is shared amongst multiple networks, with 16% shared by at least 7 resting-state networks. These overlaps, especially the existence of regions shared by numerous networks, suggest that white matter lesions in these areas might strongly impact the correlations and the communication within resting-state networks.
