Exploration of hemispheric specialization and lexico-semantic processing in unilateral temporal lobe epilepsy with verbal fluency tasks

• Published in: Neuropsychologia 2001-01, Vol.39 (6), p.635-642
• Main Authors: N'Kaoua, Bernard, Lespinet, Véronique, Barsse, Alice, Rougier, Alain, Claverie, Bernard
• Format: Article
• Language: English
• Subjects: Adult; Adult and adolescent clinical studies; Biological and medical sciences; Epilepsy, Temporal Lobe - physiopathology; Female; Functional Laterality - physiology; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Humans; Language Tests; Male; Medical sciences; Nervous system (semeiology, syndromes); Neurology; Organic mental disorders. Neuropsychology; Phonetic and semantic processing; Phonetics; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Reaction Time; Semantics; Unilateral temporal epilepsy; Verbal Behavior; Verbal fluency tasks; Vocabulary
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/S0028-3932(00)00139-1

Verbal production has been shown to rely on both hemispheres differentially. To determine how lateralized brain lesions affect the generation of isolated words, we evaluated three subject groups: normal controls ( n=22), and patients with right ( n=23), and left ( n=22) non-operated temporal lobe epilepsy (TLE) using three verbal fluency tasks (letter, phonetic, semantic). LTLE patients produced fewer words than controls in the phonetic, letter, semantic conditions, whereas RTLE patients were only impaired in the semantic task. Hence, there would be a hemispheric specialization in language where phonetic processing involves mostly the left temporal lobe and semantic aspects of production involve both temporal lobes. And, in order to study disruption of semantic lexicon involved in supermarket fluency (to name things which can be bought in a supermarket), specific indicators Tröster et al., (1998) [Tröster AI, Fields JA, Testa JA, Paul RH, Blanco CR, Hames KA, Salmon DP, Beatty WW. Cortical and subcortical influences on clustering and switching in the preformance of verbal fluency Tasks, Neuropaychologia 1998;36:295–304.] were exploited. Our results indicated that TLE groups made fewer category shifts than controls. Also, RTLE patients used labels more frequently and produced fewer exemplars. Results show the specificity of processing according to cue, and suggest that the semantic fluency deficits due to TLE be primarily due to an alteration of the mental lexicon.