Fabrizio Vecchio1, Francesca Miraglia2, Giuseppe Curcio3, Giacomo Della Marca4, Catello Vollono4, Edoardo Mazzucchi4, Placido Bramanti5, Paolo Maria Rossini6. 1. Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy. Electronic address: fabrizio.vecchio@uniroma1.it. 2. Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy. 3. Department of Life, Health and Environmental Sciences, L'Aquila, Italy. 4. Institute of Neurology, Department of Geriatrics, Neuroscience and Orthopedics, Catholic University, Policlinic A. Gemelli, Rome, Italy. 5. IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy. 6. Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy; Institute of Neurology, Department of Geriatrics, Neuroscience and Orthopedics, Catholic University, Policlinic A. Gemelli, Rome, Italy.
Abstract
OBJECTIVE: It is believed that effective connectivity and optimal network structure are essential for proper information processing in the brain. Indeed, functional abnormalities of the brain are found to be associated with pathological changes in connectivity and network structures. The aim of the present study was to explore the interictal network properties of EEG signals from temporal lobe structures in the context of fronto-temporal lobe epilepsy. METHODS: To complete this aim, the graph characteristics of the EEG data of 17 patients suffering from focal epilepsy of the fronto-temporal type, recorded during interictal periods, were examined and compared in terms of the affected versus the unaffected hemispheres. EEG connectivity analysis was performed using eLORETA software in 15 fronto-temporal regions (Brodmann Areas BAs 8, 9, 10, 11, 20, 21, 22, 37, 38, 41, 42, 44, 45, 46, 47) on both affected and unaffected hemispheres. RESULTS: The evaluation of the graph analysis parameters, such as 'global' (characteristic path length) and 'local' connectivity (clustering coefficient) showed a statistically significant interaction among side (affected and unaffected hemisphere) and Band (delta, theta, alpha, beta, gamma). Duncan post hoc testing showed an increase of the path length in the alpha band in the affected hemisphere with respect to the unaffected one, as evaluated by an inter-hemispheric marker. The affected hemisphere also showed higher values of local connectivity in the alpha band. In general, an increase of local and global graph theory parameters in the alpha band was found in the affected hemisphere. It was also demonstrated that these effects were more evident in drug-free patients than in those undergoing pharmacological therapy. CONCLUSIONS: The increased measures in the affected hemisphere of both functional local segregation and global integration could result from the combination of overlapping mechanisms, including reactive neuroplastic changes seeking to maintain constant integration and segregation properties. SIGNIFICANCE: This reactive neuroplastic mechanism seeking to maintain constant integration and segregation properties seems to be more evident in the absence of antiepileptic treatment.
OBJECTIVE: It is believed that effective connectivity and optimal network structure are essential for proper information processing in the brain. Indeed, functional abnormalities of the brain are found to be associated with pathological changes in connectivity and network structures. The aim of the present study was to explore the interictal network properties of EEG signals from temporal lobe structures in the context of fronto-temporal lobe epilepsy. METHODS: To complete this aim, the graph characteristics of the EEG data of 17 patients suffering from focal epilepsy of the fronto-temporal type, recorded during interictal periods, were examined and compared in terms of the affected versus the unaffected hemispheres. EEG connectivity analysis was performed using eLORETA software in 15 fronto-temporal regions (Brodmann Areas BAs 8, 9, 10, 11, 20, 21, 22, 37, 38, 41, 42, 44, 45, 46, 47) on both affected and unaffected hemispheres. RESULTS: The evaluation of the graph analysis parameters, such as 'global' (characteristic path length) and 'local' connectivity (clustering coefficient) showed a statistically significant interaction among side (affected and unaffected hemisphere) and Band (delta, theta, alpha, beta, gamma). Duncan post hoc testing showed an increase of the path length in the alpha band in the affected hemisphere with respect to the unaffected one, as evaluated by an inter-hemispheric marker. The affected hemisphere also showed higher values of local connectivity in the alpha band. In general, an increase of local and global graph theory parameters in the alpha band was found in the affected hemisphere. It was also demonstrated that these effects were more evident in drug-free patients than in those undergoing pharmacological therapy. CONCLUSIONS: The increased measures in the affected hemisphere of both functional local segregation and global integration could result from the combination of overlapping mechanisms, including reactive neuroplastic changes seeking to maintain constant integration and segregation properties. SIGNIFICANCE: This reactive neuroplastic mechanism seeking to maintain constant integration and segregation properties seems to be more evident in the absence of antiepileptic treatment.
Authors: Giovanni Assenza; Mario Tombini; Jacopo Lanzone; Lorenzo Ricci; Vincenzo Di Lazzaro; Sara Casciato; Alessandra Morano; Anna Teresa Giallonardo; Carlo Di Bonaventura; Ettore Beghi; Edoardo Ferlazzo; Sara Gasparini; Loretta Giuliano; Francesco Pisani; Paolo Benna; Francesca Bisulli; Fabrizio A De Falco; Silvana Franceschetti; Angela La Neve; Stefano Meletti; Barbara Mostacci; Ferdinando Sartucci; Pasquale Striano; Flavio Villani; Umberto Aguglia; Giuliano Avanzini; Vincenzo Belcastro; Amedeo Bianchi; Vittoria Cianci; Angelo Labate; Adriana Magaudda; Roberto Michelucci; Annapia Verri; Gaetano Zaccara; Vincenzo Pizza; Paolo Tinuper; Giancarlo Di Gennaro Journal: Neurol Sci Date: 2020-06-10 Impact factor: 3.307