Abstract:Amyotrophic Lateral Sclerosis (ALS) is one of the most severe neurodegenerative diseases, which is known to affect upper and lower motor neurons. In contrast to the classical tenet that ALS represents the outcome of extensive and progressive impairment of a fixed set of motor connections, recent neuroimaging findings suggest that the disease spreads along vast non-motor connections. Here, we hypothesised that functional network topology is perturbed in ALS, and that this reorganization is associated with disab… Show more
“…Moreover, with regard to the identification of potential correlations between measures of network reorganization and disability scores in patients with ALS, a recent resting-state EEG analysis revealed that some network metrics-such as the degree distribution (k), the leaf fraction (fraction of nodes with degree 1), and the tree hierarchy-were significantly different in a cohort of ALS patients compared to healthy controls. 76 Interestingly, those measures were also shown to be linearly related to disability score.…”
Section: Insights From Rs-fmri and Multimodal Studiesmentioning
confidence: 97%
“…Thus, these results seem to confirm the hypothesis that high time resolution techniques, such as MEG, might be able to capture alterations of brain functional activity also in the preclinical stage of disease. Moreover, with regard to the identification of potential correlations between measures of network reorganization and disability scores in patients with ALS, a recent resting-state EEG analysis revealed that some network metrics—such as the degree distribution ( k ), the leaf fraction (fraction of nodes with degree 1), and the tree hierarchy—were significantly different in a cohort of ALS patients compared to healthy controls 76 . Interestingly, those measures were also shown to be linearly related to disability score.Figure 4Patterns of event-related desynchronization in ALS patients compared to healthy controls during swallowing.…”
Section: Connectivity and Brain Network Changes In The Als–ftld Contimentioning
Brain imaging techniques, especially those based on magnetic resonance imaging (MRI) and magnetoencephalography (MEG), have been increasingly applied to study multiple large-scale distributed brain networks in healthy people and neurological patients. With regard to neurodegenerative disorders, amyotrophic lateral sclerosis (ALS), clinically characterized by the predominant loss of motor neurons and progressive weakness of voluntary muscles, and frontotemporal lobar degeneration (FTLD), the second most common early-onset dementia, have been proven to share several clinical, neuropathological, genetic, and neuroimaging features. Specifically, overlapping or mildly diverging brain structural and functional connectivity patterns, mostly evaluated by advanced MRI techniques-such as diffusion tensor and resting-state functional MRI (DT-MRI, RS-fMRI)-have been described comparing several ALS and FTLD populations. Moreover, though only pioneering, promising clues on connectivity patterns in the ALS-FTLD continuum may derive from MEG investigations. We will herein overview the current state of knowledge concerning the most advanced neuroimaging findings associated with clinical and genetic patterns of neurodegeneration across the ALS-FTLD continuum, underlying the possibility that network-based approaches may be useful to develop novel biomarkers of disease for adequately designing and monitoring more appropriate treatment strategies.
“…Moreover, with regard to the identification of potential correlations between measures of network reorganization and disability scores in patients with ALS, a recent resting-state EEG analysis revealed that some network metrics-such as the degree distribution (k), the leaf fraction (fraction of nodes with degree 1), and the tree hierarchy-were significantly different in a cohort of ALS patients compared to healthy controls. 76 Interestingly, those measures were also shown to be linearly related to disability score.…”
Section: Insights From Rs-fmri and Multimodal Studiesmentioning
confidence: 97%
“…Thus, these results seem to confirm the hypothesis that high time resolution techniques, such as MEG, might be able to capture alterations of brain functional activity also in the preclinical stage of disease. Moreover, with regard to the identification of potential correlations between measures of network reorganization and disability scores in patients with ALS, a recent resting-state EEG analysis revealed that some network metrics—such as the degree distribution ( k ), the leaf fraction (fraction of nodes with degree 1), and the tree hierarchy—were significantly different in a cohort of ALS patients compared to healthy controls 76 . Interestingly, those measures were also shown to be linearly related to disability score.Figure 4Patterns of event-related desynchronization in ALS patients compared to healthy controls during swallowing.…”
Section: Connectivity and Brain Network Changes In The Als–ftld Contimentioning
Brain imaging techniques, especially those based on magnetic resonance imaging (MRI) and magnetoencephalography (MEG), have been increasingly applied to study multiple large-scale distributed brain networks in healthy people and neurological patients. With regard to neurodegenerative disorders, amyotrophic lateral sclerosis (ALS), clinically characterized by the predominant loss of motor neurons and progressive weakness of voluntary muscles, and frontotemporal lobar degeneration (FTLD), the second most common early-onset dementia, have been proven to share several clinical, neuropathological, genetic, and neuroimaging features. Specifically, overlapping or mildly diverging brain structural and functional connectivity patterns, mostly evaluated by advanced MRI techniques-such as diffusion tensor and resting-state functional MRI (DT-MRI, RS-fMRI)-have been described comparing several ALS and FTLD populations. Moreover, though only pioneering, promising clues on connectivity patterns in the ALS-FTLD continuum may derive from MEG investigations. We will herein overview the current state of knowledge concerning the most advanced neuroimaging findings associated with clinical and genetic patterns of neurodegeneration across the ALS-FTLD continuum, underlying the possibility that network-based approaches may be useful to develop novel biomarkers of disease for adequately designing and monitoring more appropriate treatment strategies.
“…Network structures can also be summarized using graph theory metrics, this was explored in sensor-space in 21 patients, demonstrating a more “de-centralised” organization (149). The connectivity metric chosen in this study was phase-based, thus insensitive to any group differences in spectral power, and furthermore was significantly correlated with disability between individuals.…”
Advances in neuroimaging, complementing histopathological insights, have established a multi-system involvement of cerebral networks beyond the traditional neuromuscular pathological view of amyotrophic lateral sclerosis (ALS). The development of effective disease-modifying therapy remains a priority and this will be facilitated by improved biomarkers of motor system integrity against which to assess the efficacy of candidate drugs. Functional MRI (FMRI) is an established measure of both cerebral activity and connectivity, but there is an increasing recognition of neuronal oscillations in facilitating long-distance communication across the cortical surface. Such dynamic synchronization vastly expands the connectivity foundations defined by traditional neuronal architecture. This review considers the unique pathogenic insights afforded by the capture of cerebral disease activity in ALS using FMRI and encephalography.
“…Recent EEG studies have also described FC increases, 12 alongside global reorganization of inferred cortical network topology. 13 Magnetoencephalography (MEG) extends the localization capabilities of noninvasive neurophysiology, 14 negating dispersive effects of skull and scalp. The temporal resolution of MEG offers advantages, relevant in the assessment of dynamic cognitive processes, such as movement preparation, clinically affected by neurodegeneration.…”
ObjectiveWe sought to assess cortical function in amyotrophic lateral sclerosis (ALS) using noninvasive neural signal recording.MethodsResting-state magnetoencephalography was used to measure power fluctuations in neuronal oscillations from distributed cortical parcels in 24 patients with ALS and 24 healthy controls. A further 9 patients with primary lateral sclerosis and a group of 15 asymptomatic carriers of genetic mutations associated with ALS were also studied.ResultsIncreased functional connectivity, particularly from the posterior cingulate cortex, was demonstrated in both patient groups compared to healthy controls. Directionally similar patterns were also evident in the asymptomatic genetic mutation carrier group.ConclusionIncreased cortical functional connectivity elevation is a quantitative marker that reflects ALS pathology across its clinical spectrum, and may develop during the presymptomatic period. The amelioration of pathologic magnetoencephalography signals might be a marker sensitive enough to provide proof-of-principle in the development of future neuroprotective therapeutics.
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