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Neuron. 2014 Mar 19;81(6):1417-1428. doi: 10.1016/j.neuron.2014.01.026.

Intrinsic connectivity identifies the hippocampus as a main crossroad between Alzheimer's and semantic dementia-targeted networks.

Author information

1
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.
2
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.
3
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.
4
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.

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.

PMID:
24656258
DOI:
10.1016/j.neuron.2014.01.026
[Indexed for MEDLINE]
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