title: Intrinsic connectivity identifies the hippocampus as a main crossroad between Alzheimer's and semantic dementia-targeted networks.
abstract: Alzheimer's disease (AD) and semantic dementia (SD) are both characterized by severe atrophy in the hippocampus, a brain region underlying episodic memory; paradoxically, episodic memory is relatively preserved in SD. Here, we used intrinsic connectivity analyses and showed that the brain networks differentially vulnerable to each disease converge to the hippocampus in the healthy brain. As neurodegeneration is thought to spread within preexisting networks, the common hippocampal atrophy in both diseases is likely due to its location at the crossroad between both vulnerable networks. Yet, we showed that in the normal brain, these networks harbor different functions, with episodic memory relying on the AD-vulnerable network only. Overall, disease-associated cognitive deficits seem to reflect the disruption of targeted networks more than atrophy in specific brain regions: in AD, over hippocampal atrophy, episodic memory deficits are likely due to disconnection within a memory-related network.
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU de Caen, U1077, 14000 Caen, France. Electronic address: lajoie@cyceron.fr.
authors.forename: Renaud
authors.initials: R
authors.lastname: La Joie
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU de Caen, U1077, 14000 Caen, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Landeau
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU de Caen, U1077, 14000 Caen, France.
authors.forename: Audrey
authors.initials: A
authors.lastname: Perrotin
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU de Caen, U1077, 14000 Caen, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Bejanin
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU de Caen, U1077, 14000 Caen, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Egret
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU de Caen, U1077, 14000 Caen, France.
authors.forename: Alice
authors.initials: A
authors.lastname: Pélerin
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU de Caen, U1077, 14000 Caen, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Mézenge
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU Pontchaillou, Service de Neurologie, 35000 Rennes, France.
authors.forename: Serge
authors.initials: S
authors.lastname: Belliard
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU de Caen, Service de Neurologie, 14000 Caen, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: de La Sayette
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU de Caen, U1077, 14000 Caen, France.
authors.forename: Francis
authors.initials: F
authors.lastname: Eustache
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU de Caen, U1077, 14000 Caen, France.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Desgranges
authors.affiliation: INSERM U1077, 14000 Caen, France; Université de Caen Basse-Normandie, UMR-S1077, 14000 Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, 14000 Caen, France; CHU de Caen, U1077, 14000 Caen, France.
authors.forename: Gaël
authors.initials: G
authors.lastname: Chételat
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000473:pathology* / Q000503:physiopathology; D001284:Atrophy; D001931:Brain Mapping / Q000379:methods; D003071:Cognition; D005260:Female; D057180:Frontotemporal Dementia / Q000473:pathology* / Q000503:physiopathology; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D009415:Nerve Net / Q000473:pathology* / Q000503:physiopathology; D009483:Neuropsychological Tests