Inter-hemispheric functional connectivity changes with corpus callosum morphology in multiple sclerosis.
Multiple sclerosis (MS) affects myelin sheaths within the central nervous system, concurring to cause brain atrophy and neurodegeneration as well as gradual functional disconnections. To explore early signs of altered connectivity in MS from a structural and functional perspective, the morphology of corpus callosum (CC) was correlated with a dynamic inter-hemispheric connectivity index. Twenty mildly disabled patients affected by a relapsing-remitting (RR) form of MS (EDSS⩽3.5) and 15 healthy subjects underwent structural MRI to measure CC thickness over 100 sections and electroencephalography to assess a spectral coherence index between primary regions devoted to hand control, at rest and during an isometric handgrip. In patients, an overall CC atrophy was associated with increased lesion load. A less efficacious inter-hemispheric coherence (IHCoh) during movement was associated with CC atrophy in sections interconnecting homologous primary motor areas (anterior mid-body). In healthy controls, less efficacious IHCoh at rest was associated with a thinner CC splenium. Our data suggest that in mildly disabled RR-MS patients a covert impairment may be detected in the correlation between the structural (CC thickness) and functional (IHCoh) measures of homologous networks, whereas these two counterparts do not yet differ individually from controls.
Laboratory of Electrophysiology for Translational neuroScience (LET'S), ISTC, Consiglio Nazionale delle Ricerche, 'S. Giovanni Calibita' Fatebenefratelli Hospital, Rome I-00186, Italy; Department of Clinical Neuroscience, AFaR, 'San Giovanni Calibita' Fatebenefratelli Hospital, Rome I-00186, Italy. Electronic address: giancarlo.zito@afar.it.
G
G
Zito
Laboratory of Neuro Imaging, Department of Neurology, University of California, Los Angeles, School of Medicine, Los Angeles, CA 90095-7334, USA.
E
E
Luders
Laboratory of Electrophysiology for Translational neuroScience (LET'S), ISTC, Consiglio Nazionale delle Ricerche, 'S. Giovanni Calibita' Fatebenefratelli Hospital, Rome I-00186, Italy; Department of Clinical Neuroscience, AFaR, 'San Giovanni Calibita' Fatebenefratelli Hospital, Rome I-00186, Italy.
L
L
Tomasevic
Department of Clinical Neuroscience, AFaR, 'San Giovanni Calibita' Fatebenefratelli Hospital, Rome I-00186, Italy.
D
D
Lupoi
Laboratory of Neuro Imaging, Department of Neurology, University of California, Los Angeles, School of Medicine, Los Angeles, CA 90095-7334, USA.
A W
AW
Toga
Laboratory of Neuro Imaging, Department of Neurology, University of California, Los Angeles, School of Medicine, Los Angeles, CA 90095-7334, USA.
P M
PM
Thompson
Department of Imaging, IRCCS San Raffale Pisana, Rome I-00163, Italy; Institute of Neurology, Università Cattolica del Sacro Cuore, Rome I-00168, Italy.
P M
PM
Rossini
Department of Clinical Neuroscience, AFaR, 'San Giovanni Calibita' Fatebenefratelli Hospital, Rome I-00186, Italy.
M M
MM
Filippi
Laboratory of Electrophysiology for Translational neuroScience (LET'S), ISTC, Consiglio Nazionale delle Ricerche, 'S. Giovanni Calibita' Fatebenefratelli Hospital, Rome I-00186, Italy; Department of Imaging, IRCCS San Raffale Pisana, Rome I-00163, Italy.
F
F
Tecchio
D000328:Adult; D003337:Corpus Callosum / Q000473:pathology* / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D018737:Hand Strength; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000473:pathology* / Q000503:physiopathology*
corpus callosum; electroencephalography/event-related potentials (EEG/ERPs); inter-hemispheric coherence; relapsing-remitting multiple sclerosis (RRMS); sensorimotor control; structural magnetic resonance imaging