Distinct cortical anatomy linked to subregions of the medial temporal lobe revealed by intrinsic functional connectivity

J Neurophysiol. 2008 Jul;100(1):129-39. doi: 10.1152/jn.00077.2008. Epub 2008 Apr 2.

Abstract

The hippocampus and adjacent cortical structures in the medial temporal lobe (MTL) contribute to memory through interactions with distributed brain areas. Studies of monkey and rodent anatomy suggest that parallel pathways converge on distinct subregions of the MTL. To explore the cortical areas linked to subregions of the MTL in humans, we examined cortico-cortical and hippocampal-cortical correlations using high-resolution, functional connectivity analysis in 100 individuals. MTL seed regions extended along the anterior to posterior axis and included hippocampus and adjacent structures. Results revealed two separate brain pathways that correlated with distinct subregions within the MTL. The body of the hippocampus and posterior parahippocampal cortex correlated with lateral parietal cortex, regions along the posterior midline including posterior cingulate and retrosplenial cortex, and ventral medial prefrontal cortex. By contrast, anterior hippocampus and the perirhinal/entorhinal cortices correlated with distinct regions in the lateral temporal cortex extending into the temporal pole. The present results are largely consistent with known connectivity in the monkey and provide a novel task-independent dissociation of the parallel pathways supporting the MTL memory system in humans. The cortical pathways include regions that have undergone considerable areal expansion in humans, providing insight into how the MTL memory system has evolved to support a diverse array of cognitive domains.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Brain Mapping*
  • Female
  • Hippocampus / blood supply
  • Hippocampus / physiology
  • Humans
  • Image Processing, Computer-Assisted / methods
  • Magnetic Resonance Imaging / methods
  • Male
  • Nerve Net / blood supply
  • Nerve Net / physiology*
  • Neural Pathways / blood supply
  • Neural Pathways / physiology*
  • Oxygen / blood
  • Parahippocampal Gyrus / blood supply
  • Parahippocampal Gyrus / physiology
  • Photic Stimulation / methods
  • Psychophysics
  • Temporal Lobe / blood supply
  • Temporal Lobe / physiology*

Substances

  • Oxygen