One declarative memory system or two? The relationship between episodic and semantic memory in children with temporal lobe epilepsy

Neuropsychology. 2011 Sep;25(5):634-44. doi: 10.1037/a0023770.

Abstract

Objective: This study explored verbal semantic and episodic memory in children with unilateral temporal lobe epilepsy to determine whether they had impairments in both or only 1 aspect of memory, and to examine relations between performance in the 2 domains.

Method: Sixty-six children and adolescents (37 with seizures of left temporal lobe onset, 29 with right-sided onset) were given 4 tasks assessing different aspects of semantic memory (picture naming, fluency, knowledge of facts, knowledge of word meanings) and 2 episodic memory tasks (story recall, word list recall).

Results: High rates of impairments were observed across tasks, and no differences were found related to the laterality of the seizures. Individual patient analyses showed that there was a double dissociation between the 2 aspects of memory in that some children were impaired on episodic but not semantic memory, whereas others showed intact episodic but impaired semantic memory.

Conclusions: This double dissociation suggests that these 2 memory systems may develop independently in the context of temporal lobe pathology, perhaps related to differential effects of dysfunction in the lateral and mesial temporal lobe structures.

MeSH terms

  • Adolescent
  • Child
  • Epilepsy, Temporal Lobe / complications*
  • Epilepsy, Temporal Lobe / pathology
  • Epilepsy, Temporal Lobe / physiopathology
  • Functional Laterality
  • Humans
  • Memory / classification
  • Memory Disorders / classification*
  • Memory Disorders / complications
  • Memory Disorders / pathology
  • Memory, Episodic*
  • Mental Recall*
  • Principal Component Analysis
  • Semantics
  • Temporal Lobe / pathology
  • Temporal Lobe / physiopathology*
  • Verbal Learning