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ID 126 – Cortical connectivity and lesion volumes correlation in acute stroke patients: A study via graph theory from EEG data
Abstracts / Clinical Neurophysiology 127 (2016) e18–e132
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ID 126 – Cortical connectivity and lesion volumes correlation in acute stroke patients: A study via graph theory from EEG data— F. Vecchio a, P. Caliandro b, F. Miraglia a, F. Piludu c, C. Iacovelli b, G. Lacidogna b, G. Reale b, C. Colosimo d, P.M. Rossini a,b (a Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy, b Institute of Neurology, Dept. Geriatrics, Neuroscience & Orthopedics, Catholic University, Policlinic A. Gemelli Rome, Italy, c IRCCS Centro Neurolesi Bonino Pulejo, Messina, Italy, d Dept. Radiologys, Catholic University, Policlinic A. Gemelli Rome, Italy)
the theta band, but statistically significant only in left hemisphere stroke patients. Conclusions: After an acute stroke, brain cortex rearranges its network connections diffusely, in a frequency-dependent modality in order to face the new anatomical and functional condition. Modifications in distinct frequencies suggests that the network remodelling occurs with different modalities. Key message: Stroke-related brain network reorganization could reflect a not negligible adaptive process.
Objective: Functional connectivity is essential for brain functions. Focal brain lesions could have important remote effects on the functions of distant brain regions even if outside the damaged area. Network dysfunction may contribute to neurological deficits observed for example after stroke. We explored how functional network characteristics, measured via EEG recordings, correlate with the lesion volume on MRI. Methods: Graph characteristics of EEG data of 30 stroke patients in the acute stage (no more than 5 days after the event), were examined. EEG connectivity analysis was performed using eLORETA in both affected and unaffected hemispheres. Lesional volume were evaluated by MRI. Results: Considering all subjects as a group, in the stroke hemisphere both Path length and Clustering positively correlate with lesion volume in delta and theta bands and negatively in alpha1 band. Evaluating the contralateral hemisphere, no significant correlation was observed. Conclusions: Lesion volume correlates with a progressive reduction of brain interconnection as provided by the proportional increment of connectivity in low frequency and reduction in higher frequency bands. Key message: These results support the study of EEG via graph theory parameters for assessing the connectivity characteristics of brain networks in stroke suggesting a possible implications also in their prognosis.
doi:10.1016/j.clinph.2015.11.424
doi:10.1016/j.clinph.2015.11.423
ID 127 – Small world characteristics of cortical connectivity in acute stroke—P. Caliandro a, F. Vecchio b, F. Miraglia b, C. Iacovelli a, G. Della Marca a, G. Lacidogna a, G. Reale a, N. Di Giannantoni a, L. Padua a, P.M. Rossini a,b (a Institute of Neurology, Dept. Geriatrics, Neuroscience & Orthopedics, Catholic University, Policlinic A. Gemelli Rome, Italy, b Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy)
ID 129 – EEG characteristics in ‘‘eyes open” vs ‘‘eyes closed” conditions: Small world network architecture in healthy aging and age-related brain degeneration—F. Miraglia a, F. Vecchio a, P.M. Rossini a,b (a Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy, b Institute of Neurology, Dept. Geriatrics, Neuroscience & Orthopedics, Catholic University, Policlinic A. Gemelli Rome, Italy) Objective: Applying graph theory, we investigated how cortical sources small worldness (SW) of resting EEG in eyes-closed/open (EC/EO) differs in mild cognitive impairment (MCI) and Alzheimer’s disease (AD) subjects respect to normal elderly (Nold). Methods: EEG were recorded in 30 Nold, 30 MCI, 30 AD during EC and EO. Undirected and weighted cortical brain network was built to evaluate graph core measures. eLORETA lagged linear connectivity was used to weight the network. Results: In Nold, EO condition presented more random network (higher SW) in alpha bands and more regular organization (lower SW) in beta2 and gamma bands. In MCI, SW trend was the same, except for delta and theta bands with more ordered organization. AD showed similar trend of Nold, but with less fluctuations between the conditions. Furthermore, in both conditions, MCI SW architecture presented midway properties between AD and Nold. In low frequencies, Nold showed more random network organization, while SW parameter displayed a more ordered architecture with disease progression. Conclusions: Small world properties had different patterns in pathological aging in open eyes, with different trends in EEG frequency bands. Key message: Graph theory provides an excellent tool to characterize neuronal network capacities from coupling parameters of timevarying signals. doi:10.1016/j.clinph.2015.11.425
Objective: After cerebral ischemia, disruption and subsequent reorganization of functional connections occur both locally and remote to the lesion. Recently, brain complexity has been described using the graph theory, an elegant approach which depicts important properties of complex systems by quantifying topologies of network representations. We tested whether ischemic stroke may determine changes in smallworldness of cortical networks as measured by cortical sources of EEG. Methods: Graph characteristics of EEG of 30 consecutive stroke patients in acute stage (no more than 5 days after the event) were examined. Connectivity analysis was performed using eLORETA in both hemispheres. Results: Network rearrangements are mainly detected in delta, theta and alpha bands. Similar findings were observed in both hemispheres regardless the side of ischemic lesion: bilaterally decreased smallworldness in the delta band; similar modification observed in
ID 227 – Evidence-based modelling of nociceptive laser-evoked potentials—C. Bradley, C. Perchet, H. Bastuji, L. Garcia-Larrea (NEUROPAIN – Centre de Recherche en Neurosciences de Lyon, University Claude Bernard Lyon 1, Lyon, France) To this day, source modelling of EEG responses to nociceptive stimulation has relied on interplay between physiological hypotheses and pure mathematical estimates. Here, we propose to refine the models by integrating current knowledge in multi-modal brain imaging (fMRI and intracranial EEG) into nociceptive EEG responses modelling.
e125
ID 126 – Cortical connectivity and lesion volumes correlation in acute stroke patients: A study via graph theory from EEG data— F. Vecchio a, P. Caliandro b, F. Miraglia a, F. Piludu c, C. Iacovelli b, G. Lacidogna b, G. Reale b, C. Colosimo d, P.M. Rossini a,b (a Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy, b Institute of Neurology, Dept. Geriatrics, Neuroscience & Orthopedics, Catholic University, Policlinic A. Gemelli Rome, Italy, c IRCCS Centro Neurolesi Bonino Pulejo, Messina, Italy, d Dept. Radiologys, Catholic University, Policlinic A. Gemelli Rome, Italy)
the theta band, but statistically significant only in left hemisphere stroke patients. Conclusions: After an acute stroke, brain cortex rearranges its network connections diffusely, in a frequency-dependent modality in order to face the new anatomical and functional condition. Modifications in distinct frequencies suggests that the network remodelling occurs with different modalities. Key message: Stroke-related brain network reorganization could reflect a not negligible adaptive process.
Objective: Functional connectivity is essential for brain functions. Focal brain lesions could have important remote effects on the functions of distant brain regions even if outside the damaged area. Network dysfunction may contribute to neurological deficits observed for example after stroke. We explored how functional network characteristics, measured via EEG recordings, correlate with the lesion volume on MRI. Methods: Graph characteristics of EEG data of 30 stroke patients in the acute stage (no more than 5 days after the event), were examined. EEG connectivity analysis was performed using eLORETA in both affected and unaffected hemispheres. Lesional volume were evaluated by MRI. Results: Considering all subjects as a group, in the stroke hemisphere both Path length and Clustering positively correlate with lesion volume in delta and theta bands and negatively in alpha1 band. Evaluating the contralateral hemisphere, no significant correlation was observed. Conclusions: Lesion volume correlates with a progressive reduction of brain interconnection as provided by the proportional increment of connectivity in low frequency and reduction in higher frequency bands. Key message: These results support the study of EEG via graph theory parameters for assessing the connectivity characteristics of brain networks in stroke suggesting a possible implications also in their prognosis.
doi:10.1016/j.clinph.2015.11.424
doi:10.1016/j.clinph.2015.11.423
ID 127 – Small world characteristics of cortical connectivity in acute stroke—P. Caliandro a, F. Vecchio b, F. Miraglia b, C. Iacovelli a, G. Della Marca a, G. Lacidogna a, G. Reale a, N. Di Giannantoni a, L. Padua a, P.M. Rossini a,b (a Institute of Neurology, Dept. Geriatrics, Neuroscience & Orthopedics, Catholic University, Policlinic A. Gemelli Rome, Italy, b Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy)
ID 129 – EEG characteristics in ‘‘eyes open” vs ‘‘eyes closed” conditions: Small world network architecture in healthy aging and age-related brain degeneration—F. Miraglia a, F. Vecchio a, P.M. Rossini a,b (a Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy, b Institute of Neurology, Dept. Geriatrics, Neuroscience & Orthopedics, Catholic University, Policlinic A. Gemelli Rome, Italy) Objective: Applying graph theory, we investigated how cortical sources small worldness (SW) of resting EEG in eyes-closed/open (EC/EO) differs in mild cognitive impairment (MCI) and Alzheimer’s disease (AD) subjects respect to normal elderly (Nold). Methods: EEG were recorded in 30 Nold, 30 MCI, 30 AD during EC and EO. Undirected and weighted cortical brain network was built to evaluate graph core measures. eLORETA lagged linear connectivity was used to weight the network. Results: In Nold, EO condition presented more random network (higher SW) in alpha bands and more regular organization (lower SW) in beta2 and gamma bands. In MCI, SW trend was the same, except for delta and theta bands with more ordered organization. AD showed similar trend of Nold, but with less fluctuations between the conditions. Furthermore, in both conditions, MCI SW architecture presented midway properties between AD and Nold. In low frequencies, Nold showed more random network organization, while SW parameter displayed a more ordered architecture with disease progression. Conclusions: Small world properties had different patterns in pathological aging in open eyes, with different trends in EEG frequency bands. Key message: Graph theory provides an excellent tool to characterize neuronal network capacities from coupling parameters of timevarying signals. doi:10.1016/j.clinph.2015.11.425
Objective: After cerebral ischemia, disruption and subsequent reorganization of functional connections occur both locally and remote to the lesion. Recently, brain complexity has been described using the graph theory, an elegant approach which depicts important properties of complex systems by quantifying topologies of network representations. We tested whether ischemic stroke may determine changes in smallworldness of cortical networks as measured by cortical sources of EEG. Methods: Graph characteristics of EEG of 30 consecutive stroke patients in acute stage (no more than 5 days after the event) were examined. Connectivity analysis was performed using eLORETA in both hemispheres. Results: Network rearrangements are mainly detected in delta, theta and alpha bands. Similar findings were observed in both hemispheres regardless the side of ischemic lesion: bilaterally decreased smallworldness in the delta band; similar modification observed in
ID 227 – Evidence-based modelling of nociceptive laser-evoked potentials—C. Bradley, C. Perchet, H. Bastuji, L. Garcia-Larrea (NEUROPAIN – Centre de Recherche en Neurosciences de Lyon, University Claude Bernard Lyon 1, Lyon, France) To this day, source modelling of EEG responses to nociceptive stimulation has relied on interplay between physiological hypotheses and pure mathematical estimates. Here, we propose to refine the models by integrating current knowledge in multi-modal brain imaging (fMRI and intracranial EEG) into nociceptive EEG responses modelling.