title: Cortical brain connectivity evaluated by graph theory in dementia: a correlation study between functional and structural data.
abstract: A relatively new approach to brain function in neuroscience is the "functional connectivity", namely the synchrony in time of activity in anatomically-distinct but functionally-collaborating brain regions. On the other hand, diffusion tensor imaging (DTI) is a recently developed magnetic resonance imaging (MRI)-based technique with the capability to detect brain structural connection with fractional anisotropy (FA) identification. FA decrease has been observed in the corpus callosum of subjects with Alzheimer's disease (AD) and mild cognitive impairment (MCI, an AD prodromal stage). Corpus callosum splenium DTI abnormalities are thought to be associated with functional disconnections among cortical areas. This study aimed to investigate possible correlations between structural damage, measured by MRI-DTI, and functional abnormalities of brain integration, measured by characteristic path length detected in resting state EEG source activity (40 participants: 9 healthy controls, 10 MCI, 10 mild AD, 11 moderate AD). For each subject, undirected and weighted brain network was built to evaluate graph core measures. eLORETA lagged linear connectivity values were used as weight of the edges of the network. Results showed that callosal FA reduction is associated to a loss of brain interhemispheric functional connectivity characterized by increased delta and decreased alpha path length. These findings suggest that "global" (average network shortest path length representing an index of how efficient is the information transfer between two parts of the network) functional measure can reflect the reduction of fiber connecting the two hemispheres as revealed by DTI analysis and also anticipate in time this structural loss.
authors.affiliation: Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Vecchio
authors.affiliation: Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Miraglia
authors.affiliation: Department of Life, Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Curcio
authors.affiliation: Dementia Unit, Neurology, Università Campus Bio-Medico di Roma, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Altavilla
authors.affiliation: Dementia Unit, Neurology, Università Campus Bio-Medico di Roma, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Scrascia
authors.affiliation: Dementia Unit, Neurology, Università Campus Bio-Medico di Roma, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Giambattistelli
authors.affiliation: Radiology Unit, Università Campus Bio-Medico di Roma, Italy.
authors.forename: Carlo Cosimo
authors.initials: CC
authors.lastname: Quattrocchi
authors.affiliation: IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy.
authors.forename: Placido
authors.initials: P
authors.lastname: Bramanti
authors.affiliation: Dementia Unit, Neurology, Università Campus Bio-Medico di Roma, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Vernieri
authors.affiliation: Brain Connectivity Laboratory, IRCCS San Raffaele Pisana, Rome, Italy Institute of Neurology, Dept. Geriatrics, Neuroscience & Orthopedics, Catholic University, Policlinic A. Gemelli Rome, Italy.
authors.forename: Paolo Maria
authors.initials: PM
authors.lastname: Rossini
mesh_terms: D016880:Anisotropy; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000473:pathology* / Q000503:physiopathology*; D060825:Cognitive Dysfunction; D003704:Dementia / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008609:Mental Status Schedule; D009415:Nerve Net / Q000473:pathology*; D013223:Statistics as Topic
keywords: Alzheimer's disease; EEG; delta and alpha bands; diffusion tensor imaging; functional connectivity; graph theory; mild cognitive impairment; sLORETA/eLORETA