Abstracts

RATIONALE: The goal of the present study was to examine word priming and the use of syllabic search procedures in French speaking epileptic patients with unilateral hippocampal sclerosis. A word stem completion initially designed by Peretz et al (1998) was used to investigate both the presence of indirect memory and the effect of syllabic structure in the completion of stems with primed and unprimed words.
METHODS: Two experiments involving different groups of patients with right (RHA) or left (LHA) hippocampal atrophy as well as normal control (NC) subjects were carried out by using different versions of word stem completion tasks.
RESULTS: Both experiments showed that unilateral hippocampal lesion does not preclude the expression of priming. Moreover, the results showed that LHA patients fail to demonstrate an effect of the syllabic structure in the completion of primed words in both experiments, despite similar levels of priming scores. This data contrasts with the use of syllabic search procedure in word stem completion demonstrated in NC as well as in RHA subjects in experiment 2. This deficit cannot be attributed to an impaired retrieval from the word lexicon since the use of syllabic search strategy has been observed in the completion of unprimed words in all groups.
CONCLUSIONS: The data reported in these two experiments illustrate a dissociation in LHA subjects in the nature of their lexical search when word retrieval depends on prior presentation or not. This result seems to indicate an involvement of left hippocampal structures in implicit retrieval of words.