Bilateral inferior frontal language-related activation correlates with verbal recall in patients with left temporal lobe epilepsy and typical language distribution

Abstract

Language fMRI has been used in the presurgical evaluation of drug-resistant temporal lobe epilepsy patients. Previous studies have demonstrated that left temporal lobe epilepsy (LTLE) patients with atypical language lateralization are at lower risk of postsurgical verbal memory decline, hypothesizing co-occurrence of verbal memory and language reorganization presurgically. Furthermore, it has been proposed that the recruitment of right frontal language-related areas is associated with the preservation of verbal memory performance in these patients. However, less is known about the correlation between these functions specifically in LTLE patients with left language dominance, although they are more prone to postsurgical verbal memory decline. The aim of the present study was to investigate whether the relationship between verbal memory scores and frontal language activation is also observed in LTLE patients with typical language dominance. Eighteen healthy controls, 12 right temporal lobe epilepsy patients and 12 LTLE patients with typical language distribution as assessed by an fMRI verbal fluency task were selected. Verbal memory scores were obtained from the patients’ neuropsychological presurgical evaluation. Our results showed a positive correlation between verbal recall and activation of bilateral inferior frontal areas in LTLE patients. These results support the hypothesis of a link between language representation in inferior frontal areas and hippocampal functioning, and indicate that both hemispheres are related to the preservation of verbal memory in patients with hippocampal damage and typical language dominance.