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A Dissociation between Implicit and Explicit Verbal Memory in Left Temporal Lobe Epilepsy
Author(s) -
Del Vecchio Nicole,
Liporace Joyce,
Nei Maromi,
Sperling Michael,
Tracy Joseph
Publication year - 2004
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/j.0013-9580.2004.28903.x
Subject(s) - automaticity , temporal lobe , recall , dissociation (chemistry) , implicit memory , psychology , explicit memory , verbal memory , epilepsy , audiology , cognitive psychology , cognition , neuroscience , episodic memory , medicine , chemistry
Summary: Purpose: Temporal lobe epilepsy patients are well known to present deficits on explicit verbal memory procedures (e.g., recall, recognition). The integrity of implicit memory procedures in these patients is not established. Previous studies in this area used implicit memory measures contaminated by the effects of explicit memory. Methods: We examined the integrity of verbal implicit and explicit memory in left temporal lobe epilepsy (LTLE) patients and hypothesized that a clear dissociation in performance would be found with a relative preservation of implicit memory. TLE patients (n = 15) and age‐ and education‐matched healthy normal patients (n = 15) were shown a 40‐word study list, followed by a test phase requiring completion of word stems based on the study words or new/unseen words. Experimental conditions involved instructions to provide either the old (study) words or novel/nonlist words when completing the stem. Measures of automaticity and recollection provided uncontaminated indices of implicit and explicit memory, respectively. Results: The data showed a significant difference (p < 0.001) between the patients (Recollection, 0.12; SD, 0.18) and controls (0.50, SD, 0.15) on the measure of explicit memory. In contrast, the patients (Automaticity, 0.51; SD, 0.11) and controls (0.45, SD, 0.18) performed similarly on the implicit memory measure, with patient scores clearly at normative levels based on other Process Dissociation Procedure data. Conclusions: The data demonstrate the integrity of implicit memory in LTLE patients. Finding a dissociation between the two forms of verbal memory in LTLE patients provides evidence that they rely on different neuroanatomic systems.