Differential effect of side of temporal lobe epilepsy on lateralization of hippocampal, temporolateral, and inferior frontal activation patterns during a verbal episodic memory task

Epilepsy Behav. 2008 Apr;12(3):382-7. doi: 10.1016/j.yebeh.2007.11.003. Epub 2007 Dec 26.


The encoding of verbal stimuli elicits left-lateralized activation patterns within the medial temporal lobes in healthy adults. In our study, patients with left- and right-sided temporal lobe epilepsy (LTLE, RTLE) were investigated during the encoding and retrieval of word-pair associates using functional magnetic resonance imaging. Functional asymmetry of activation patterns in hippocampal, inferior frontal, and temporolateral neocortical areas associated with language functions was analyzed. Hippocampal activation patterns in patients with LTLE were more right-lateralized than those in patients with RTLE (P<0.05). There were no group differences with respect to lateralization in frontal or temporolateral regions of interest (ROIs). For both groups, frontal cortical activation patterns were significantly more left-lateralized than hippocampal patterns (P<0.05). For patients with LTLE, there was a strong trend toward a difference in functional asymmetry between the temporolateral and hippocampal ROIs (P=0.059). A graded effect of epileptic activity on laterality of the different regional activation patterns is discussed.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Cerebral Cortex / blood supply
  • Cerebral Cortex / physiopathology*
  • Child
  • Epilepsy, Temporal Lobe / pathology*
  • Epilepsy, Temporal Lobe / physiopathology
  • Female
  • Frontal Lobe / blood supply
  • Frontal Lobe / physiopathology
  • Functional Laterality / physiology*
  • Hippocampus / blood supply
  • Hippocampus / physiopathology
  • Humans
  • Magnetic Resonance Imaging / methods
  • Male
  • Memory / physiology*
  • Middle Aged
  • Neuropsychological Tests
  • Numerical Analysis, Computer-Assisted
  • Oxygen / blood
  • Temporal Lobe / blood supply
  • Temporal Lobe / physiopathology
  • Verbal Learning / physiology*


  • Oxygen