Slide Slam G13
Lexical retrieval in naming and spontaneous discourse in temporal lobe epilepsy
Anna Yurchenko1,2, Alexander Golovteev2, Dinara Sharafutdinova1; 1National Research University Higher School of Economics, Moscow, Russia, 2Epilepsy Center, Moscow, Russia
Introduction: Previous research, that assessed noun and verb production, showed that individuals with temporal lobe epilepsy (TLE) have difficulties with language production at the single word level, whereas spontaneous speech typically remained unattended. The goal of our study was to additionally investigate the lexical characteristics of fluent discourse (lexical diversity) in individuals with left and right TLE as compared to healthy Russian speakers. Methods: 26 individuals with left TLE (17 females, mean age = 29.2, SD = 5.6, mean years of education = 13.7, SD = 2.4), 26 individuals with right TLE (13 females, mean age = 28.5, SD = 5.6, mean years of education = 13.7, SD = 3.3), and 26 healthy Russian speakers (16 females, mean age = 31.5, SD = 9.5, mean years of education = 15, SD = 1.9) were enrolled in the study. During the discourse production task, participants were asked to create a story based on a complex picture representing a situation. Noun and verb production was assessed using object and action naming tests. The data analysis included linear regression modeling with group, education, and clinical parameters as independent factors. Dependent measures were the length and Measure of Lexical Diversity in Text (MLTD) for the discourse and percent of correct answers for the naming tests. Results: As compared to the healthy controls, individuals with left and right TLE showed lower MLTD-values (49.7 in left TLE vs. 65.6 in healthy controls, 56.3 in right TLE vs. 65.6 in healthy controls; adjusted r-squared = 0.09, p = 0.012), whereas no difference was observed in the length of the discourse. In both groups of individuals with TLE, performance was also impaired on object (87.5% in left TLE vs. 97.6% in healthy controls, 91.6% in right TLE vs. 97.6% in healthy controls; adjusted r-squared = 0.27, p < 0.001) and action (90.4% in left TLE vs. 97.8% in healthy controls, 92.7% in right TLE vs. 97.8% in healthy controls; adjusted r-squared = 0.18, p < 0.001) naming. No differences were observed between the individuals with left and right TLE in any of the tasks. Conclusion: Our naming tests results are in line with previous studies demonstrating impaired single word production in individuals with left and right TLE. In addition, we observed decreased lexical diversity in spontaneous discourse, irrespective of the lateralization of the epileptogenic focus. We suggest that the reduced performance on both language levels reflects difficulties with lexical retrieval and/or reduced vocabulary size.