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

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


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / pathology*
  • Alzheimer Disease / physiopathology
  • Atrophy
  • Brain Mapping / methods
  • Cognition
  • Female
  • Frontotemporal Dementia / pathology*
  • Frontotemporal Dementia / physiopathology
  • Hippocampus / pathology*
  • Hippocampus / physiopathology
  • Humans
  • Male
  • Memory / physiology
  • Middle Aged
  • Nerve Net / pathology*
  • Nerve Net / physiopathology
  • Neuropsychological Tests