title: Altered functional connectivity networks in acallosal and socially impaired BTBR mice.
abstract: Agenesis of the corpus callosum (AgCC) is a congenital condition associated with wide-ranging emotional and social impairments often overlapping with the diagnostic criteria for autism. Mapping functional connectivity in the acallosal brain can help identify neural correlates of the deficits associated with this condition, and elucidate how congenital white matter alterations shape the topology of large-scale functional networks. By using resting-state BOLD functional magnetic resonance imaging (rsfMRI), here we show that acallosal BTBR T+tpr3tf/J (BTBR) mice, an idiopathic model of autism, exhibit impaired intra-hemispheric connectivity in fronto-cortical, but not in posterior sensory cortical areas. We also document profoundly altered subcortical and intra-hemispheric connectivity networks, with evidence of marked fronto-thalamic and striatal disconnectivity, along with aberrant spatial extension and strength of ipsilateral and local connectivity. Importantly, inter-hemispheric tracing of monosynaptic connections in the primary visual cortex using recombinant rabies virus confirmed the absence of direct homotopic pathways between posterior cortical areas of BTBR mice, suggesting a polysynaptic origin for the synchronous rsfMRI signal observed in these regions. Collectively, the observed long-range connectivity impairments recapitulate hallmark neuroimaging findings in autism, and are consistent with the behavioral phenotype of BTBR mice. In contrast to recent rsfMRI studies in high functioning AgCC individuals, the profound fronto-cortical and subcortical disconnectivity mapped suggest that compensatory mechanism may not necessarily restore the full connectional topology of the brain, resulting in residual connectivity alterations that serve as plausible substrates for the cognitive and emotional deficits often associated with AgCC.
authors.affiliation: Center for Neuroscience and Cognitive Systems @ UniTn, Istituto Italiano di Tecnologia, 38068, Rovereto, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Sforazzini
authors.affiliation: Center for Neuroscience and Cognitive Systems @ UniTn, Istituto Italiano di Tecnologia, 38068, Rovereto, Italy.|Department of Biology, Unit of Cell and Developmental Biology, University of Pisa, Pisa, Italy.
authors.forename: Alice
authors.initials: A
authors.lastname: Bertero
authors.affiliation: Istituto Italiano di Tecnologia, Pavis Lab, Genoa, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Dodero
authors.affiliation: Center for Neuroscience and Cognitive Systems @ UniTn, Istituto Italiano di Tecnologia, 38068, Rovereto, Italy.
authors.forename: Gergely
authors.initials: G
authors.lastname: David
authors.affiliation: Center for Neuroscience and Cognitive Systems @ UniTn, Istituto Italiano di Tecnologia, 38068, Rovereto, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Galbusera
authors.affiliation: Neurotoxicology and Neuroendocrinology Section, Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Scattoni
authors.affiliation: Center for Neuroscience and Cognitive Systems @ UniTn, Istituto Italiano di Tecnologia, 38068, Rovereto, Italy.|Department of Biology, Unit of Cell and Developmental Biology, University of Pisa, Pisa, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Pasqualetti
authors.affiliation: Center for Neuroscience and Cognitive Systems @ UniTn, Istituto Italiano di Tecnologia, 38068, Rovereto, Italy. alessandro.gozzi@iit.it.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Gozzi
mesh_terms: D061085:Agenesis of Corpus Callosum / Q000503:physiopathology; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D063132:Connectome / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D019579:Neocortex / Q000473:pathology; D009415:Nerve Net / Q000503:physiopathology; D059906:Neuroimaging / Q000379:methods; D012919:Social Behavior; D013788:Thalamus / Q000473:pathology; D014793:Visual Cortex / Q000503:physiopathology
keywords: Autism; BTBR; Connectivity; Corpus callosum; Mouse retrograde tracing; fMRI