Alzheimer’s disease (AD) is typically associated with an impairment of brain networks and global ... more Alzheimer’s disease (AD) is typically associated with an impairment of brain networks and global cognitive function in aging. In this vein, the present study tested the hypothesis that the functional coupling of resting cortical electroencephalographic (EEG) rhythms is progressively abnormal in amnesic mild cognitive impairment (MCI) and AD subjects. Eyes-closed resting EEG data were recorded (10–20 system) in 33 mild AD, 52 amnesic MCI, and 47 normal elderly subjects (Nold). EEG rhythms of interest were delta (2–4 Hz), theta (4–8 Hz), alpha1 (8–10 Hz), alpha2 (10–13 Hz), beta1 (13–20 Hz), beta2 (20–30 Hz), and gamma (30–40 Hz). The global functional coupling of the EEG rhythms was indexed by means of spectral coherence for all combinations of electrode pairs (i.e., total coherence). The main results showed that the total coherence of delta rhythms was higher in the AD than the MCI group. It was also higher in the MCI than the Nold group. Furthermore, the delta total coherence was negatively correlated with global cognition (Mini Mental State Examination score) across the Nold, MCI, and AD subjects. Finally, the alpha1 total coherence was lower in the AD group than in the MCI and Nold groups. These results suggest that in the AD process an impairment of brain networks and global cognition is associated with a frequency-specific modulation of the global functional coupling of resting EEG rhythms.
It has been reported that GSM electromagnetic fields (GSM-EMFs) of mobile phones modulate--after ... more It has been reported that GSM electromagnetic fields (GSM-EMFs) of mobile phones modulate--after a prolonged exposure--inter-hemispheric synchronization of temporal and frontal resting electroencephalographic (EEG) rhythms in normal young subjects [Vecchio et al., 2007]. Here we tested the hypothesis that this effect can vary on physiological aging as a sign of changes in the functional organization of cortical neural synchronization. Eyes-closed resting EEG data were recorded in 16 healthy elderly subjects and 5 young subjects in the two conditions of the previous reference study. The GSM device was turned on (45 min) in one condition and was turned off (45 min) in the other condition. Spectral coherence evaluated the inter-hemispheric synchronization of EEG rhythms at the following bands: delta (about 2-4 Hz), theta (about 4-6 Hz), alpha 1 (about 6-8 Hz), alpha 2 (about 8-10 Hz), and alpha 3 (about 10-12 Hz). The aging effects were investigated comparing the inter-hemispheric EEG coherence in the elderly subjects vs. a young group formed by 15 young subjects (10 young subjects of the reference study; Vecchio et al., 2007). Compared with the young subjects, the elderly subjects showed a statistically significant (p<0.001) increment of the inter-hemispheric coherence of frontal and temporal alpha rhythms (about 8-12 Hz) during the GSM condition. These results suggest that GSM-EMFs of a mobile phone affect inter-hemispheric synchronization of the dominant (alpha) EEG rhythms as a function of the physiological aging. This study provides further evidence that physiological aging is related to changes in the functional organization of cortical neural synchronization.
In eight normal rubjects instructed to perform selfpaced brisk right middle finger extension, sou... more In eight normal rubjects instructed to perform selfpaced brisk right middle finger extension, source location of the averaged potential associated with the beginning and the execution of voluntary movement (Motor Potential) was calculated using different mathematical source and head models and minimization strategies. Electroencephalogram was recorded by 28 Ag- AgCl scalp electrodes positioned according to expanded 10-20 system. Source location
In the present study a modern high resolution electroencephalography (EEG) technique was used to ... more In the present study a modern high resolution electroencephalography (EEG) technique was used to investigate the dynamic functional topography of human cortical activity related to simple unilateral internally triggered finger movements. The sensorimotor area (M1-S1) contralateral to the movement as well as the supplementary motor area (SMA) and to a lesser extent the ipsilateral M1-S1 were active during the preparation and execution of these movements. These findings suggest that both hemispheres may cooperate in both planning and production of simple unilateral volitional acts.
BackgroundGraph theory models a network by its nodes and connections. “Degree” hubs reflect node ... more BackgroundGraph theory models a network by its nodes and connections. “Degree” hubs reflect node centrality, while “connector” hubs are those linked to several clusters of nodes. Here we compared hubs modelled from measures of interdependencies of between‐electrode resting‐state eyes‐closed electroencephalography (rsEEG) rhythms in normal old (Nold) and Alzheimer’s disease dementia (ADD) participants. As ADD is considered as a “network disease” and is typically associated with abnormal rsEEG delta (< 4 Hz) and alpha rhythms (8‐12 Hz) over associative posterior areas, we predicted abnormal posterior hubs from measures of interdependencies of those rhythms in ADD as compared to Nold participants.MethodTo report robust results, we measured interdependencies of rsEEG rhythms from delta to gamma bands (2‐40 Hz) by both bivariate linear lagged connectivity and multivariate (directional) isolated lagged effective coherence. Furthermore, we used three different definitions of “connector” hub.ResultConvergent results showed that in both Nold and ADD groups, there were significant parietal “degree” and “connector” hubs derived from alpha rhythms. These hubs had a prominent outward “directionality” in the two groups, but that “directionality” was lower in ADD than Nold participants (Figure 1).ConclusionIndependent methodologies and hub definitions suggest that ADD patients may be characterized by low outward “directionality” of topologically partially resilient parietal “degree” and “connector” hubs derived from rsEEG alpha rhythms. Combined use of independent methodologies in rsEEG studies may produce robust results in clinical applications in ADD patients.
Cortical network modularity underpins cognitive functions, so we hypothesized its progressive der... more Cortical network modularity underpins cognitive functions, so we hypothesized its progressive derangement along the course of frontotemporal (FTD) and Alzheimer's (AD) dementing diseases. EEG was recorded in 18 FTD, 18 AD, and 20 healthy controls (HC). In the FTD and AD patients, the EEG recordings were performed at the prodromal stage of dementia, at the onset of dementia, and three years after the onset of dementia. HC underwent three EEG recordings at 2-3-year time interval. Information flows underlying EEG activity recorded at electrode pairs were estimated by means of Mutual Information (MI) analysis. The functional organization of the cortical network was modelled by means of the Graph theory analysis on MI adjacency matrices. Graph theory analysis showed that the main hub of HC (Parietal area) was lost in FTD patients at onset of dementia, substituted by provincial hubs in frontal leads. No changes in global network organization were found in AD. Despite a progressive cognitive impairment during the FTD and AD progression, only the FTD patients showed a derangement in the cortical network modularity, possibly due to dysfunctions in frontal functional connectivity.
Alzheimer’s disease (AD) is typically associated with an impairment of brain networks and global ... more Alzheimer’s disease (AD) is typically associated with an impairment of brain networks and global cognitive function in aging. In this vein, the present study tested the hypothesis that the functional coupling of resting cortical electroencephalographic (EEG) rhythms is progressively abnormal in amnesic mild cognitive impairment (MCI) and AD subjects. Eyes-closed resting EEG data were recorded (10–20 system) in 33 mild AD, 52 amnesic MCI, and 47 normal elderly subjects (Nold). EEG rhythms of interest were delta (2–4 Hz), theta (4–8 Hz), alpha1 (8–10 Hz), alpha2 (10–13 Hz), beta1 (13–20 Hz), beta2 (20–30 Hz), and gamma (30–40 Hz). The global functional coupling of the EEG rhythms was indexed by means of spectral coherence for all combinations of electrode pairs (i.e., total coherence). The main results showed that the total coherence of delta rhythms was higher in the AD than the MCI group. It was also higher in the MCI than the Nold group. Furthermore, the delta total coherence was negatively correlated with global cognition (Mini Mental State Examination score) across the Nold, MCI, and AD subjects. Finally, the alpha1 total coherence was lower in the AD group than in the MCI and Nold groups. These results suggest that in the AD process an impairment of brain networks and global cognition is associated with a frequency-specific modulation of the global functional coupling of resting EEG rhythms.
It has been reported that GSM electromagnetic fields (GSM-EMFs) of mobile phones modulate--after ... more It has been reported that GSM electromagnetic fields (GSM-EMFs) of mobile phones modulate--after a prolonged exposure--inter-hemispheric synchronization of temporal and frontal resting electroencephalographic (EEG) rhythms in normal young subjects [Vecchio et al., 2007]. Here we tested the hypothesis that this effect can vary on physiological aging as a sign of changes in the functional organization of cortical neural synchronization. Eyes-closed resting EEG data were recorded in 16 healthy elderly subjects and 5 young subjects in the two conditions of the previous reference study. The GSM device was turned on (45 min) in one condition and was turned off (45 min) in the other condition. Spectral coherence evaluated the inter-hemispheric synchronization of EEG rhythms at the following bands: delta (about 2-4 Hz), theta (about 4-6 Hz), alpha 1 (about 6-8 Hz), alpha 2 (about 8-10 Hz), and alpha 3 (about 10-12 Hz). The aging effects were investigated comparing the inter-hemispheric EEG coherence in the elderly subjects vs. a young group formed by 15 young subjects (10 young subjects of the reference study; Vecchio et al., 2007). Compared with the young subjects, the elderly subjects showed a statistically significant (p<0.001) increment of the inter-hemispheric coherence of frontal and temporal alpha rhythms (about 8-12 Hz) during the GSM condition. These results suggest that GSM-EMFs of a mobile phone affect inter-hemispheric synchronization of the dominant (alpha) EEG rhythms as a function of the physiological aging. This study provides further evidence that physiological aging is related to changes in the functional organization of cortical neural synchronization.
In eight normal rubjects instructed to perform selfpaced brisk right middle finger extension, sou... more In eight normal rubjects instructed to perform selfpaced brisk right middle finger extension, source location of the averaged potential associated with the beginning and the execution of voluntary movement (Motor Potential) was calculated using different mathematical source and head models and minimization strategies. Electroencephalogram was recorded by 28 Ag- AgCl scalp electrodes positioned according to expanded 10-20 system. Source location
In the present study a modern high resolution electroencephalography (EEG) technique was used to ... more In the present study a modern high resolution electroencephalography (EEG) technique was used to investigate the dynamic functional topography of human cortical activity related to simple unilateral internally triggered finger movements. The sensorimotor area (M1-S1) contralateral to the movement as well as the supplementary motor area (SMA) and to a lesser extent the ipsilateral M1-S1 were active during the preparation and execution of these movements. These findings suggest that both hemispheres may cooperate in both planning and production of simple unilateral volitional acts.
BackgroundGraph theory models a network by its nodes and connections. “Degree” hubs reflect node ... more BackgroundGraph theory models a network by its nodes and connections. “Degree” hubs reflect node centrality, while “connector” hubs are those linked to several clusters of nodes. Here we compared hubs modelled from measures of interdependencies of between‐electrode resting‐state eyes‐closed electroencephalography (rsEEG) rhythms in normal old (Nold) and Alzheimer’s disease dementia (ADD) participants. As ADD is considered as a “network disease” and is typically associated with abnormal rsEEG delta (< 4 Hz) and alpha rhythms (8‐12 Hz) over associative posterior areas, we predicted abnormal posterior hubs from measures of interdependencies of those rhythms in ADD as compared to Nold participants.MethodTo report robust results, we measured interdependencies of rsEEG rhythms from delta to gamma bands (2‐40 Hz) by both bivariate linear lagged connectivity and multivariate (directional) isolated lagged effective coherence. Furthermore, we used three different definitions of “connector” hub.ResultConvergent results showed that in both Nold and ADD groups, there were significant parietal “degree” and “connector” hubs derived from alpha rhythms. These hubs had a prominent outward “directionality” in the two groups, but that “directionality” was lower in ADD than Nold participants (Figure 1).ConclusionIndependent methodologies and hub definitions suggest that ADD patients may be characterized by low outward “directionality” of topologically partially resilient parietal “degree” and “connector” hubs derived from rsEEG alpha rhythms. Combined use of independent methodologies in rsEEG studies may produce robust results in clinical applications in ADD patients.
Cortical network modularity underpins cognitive functions, so we hypothesized its progressive der... more Cortical network modularity underpins cognitive functions, so we hypothesized its progressive derangement along the course of frontotemporal (FTD) and Alzheimer's (AD) dementing diseases. EEG was recorded in 18 FTD, 18 AD, and 20 healthy controls (HC). In the FTD and AD patients, the EEG recordings were performed at the prodromal stage of dementia, at the onset of dementia, and three years after the onset of dementia. HC underwent three EEG recordings at 2-3-year time interval. Information flows underlying EEG activity recorded at electrode pairs were estimated by means of Mutual Information (MI) analysis. The functional organization of the cortical network was modelled by means of the Graph theory analysis on MI adjacency matrices. Graph theory analysis showed that the main hub of HC (Parietal area) was lost in FTD patients at onset of dementia, substituted by provincial hubs in frontal leads. No changes in global network organization were found in AD. Despite a progressive cognitive impairment during the FTD and AD progression, only the FTD patients showed a derangement in the cortical network modularity, possibly due to dysfunctions in frontal functional connectivity.
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