Enhanced activity during associative encoding in the affected hippocampus in right temporal lobe epilepsy patients

Brain Res. 2009 Nov 10:1297:112-7. doi: 10.1016/j.brainres.2009.08.036. Epub 2009 Aug 21.

Abstract

Mnestic deficits represent the core cognitive impairment of patients with temporal lobe epilepsy (TLE), irrespective of the existence of overt morphological lesions. Compared to controls, patients with symptomatic TLE show altered functional activation patterns in fMRI studies on memory processes. But, so far, such studies have rarely investigated patients with temporal lobe epilepsy of unknown cause. Therefore, in the current study, a small sample of 6 right TLE patients with normal structural MRIs was compared to controls with respect to brain activity during encoding of face-name associations using fMRI. Compared to controls, patients retrieved fewer face-name associations correctly, but showed significantly greater activation of the affected hippocampus for successfully encoded stimuli. Therefore, higher hippocampal activation seems necessary for successful encoding of associations in patients compared to controls. But, this process is not entirely successful since the patients cannot achieve the same performance as controls. In conclusion, the hyperactivation of the hippocampus might represent a compensational but inefficient process.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / physiology
  • Adolescent
  • Adult
  • Association Learning / physiology*
  • Brain Mapping
  • Epilepsy, Temporal Lobe / physiopathology*
  • Epilepsy, Temporal Lobe / psychology
  • Evoked Potentials / physiology*
  • Face / physiology
  • Female
  • Functional Laterality / physiology*
  • Hippocampus / anatomy & histology
  • Hippocampus / physiopathology*
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Memory / physiology
  • Memory Disorders / diagnosis
  • Memory Disorders / pathology
  • Memory Disorders / physiopathology
  • Middle Aged
  • Neuronal Plasticity / physiology
  • Neuropsychological Tests
  • Pattern Recognition, Visual / physiology
  • Photic Stimulation
  • Symbolism*
  • Verbal Behavior / physiology
  • Young Adult