Neuroanatomical correlates of disproportionate damage of lexical–semantic categories in epilepsy of the medial temporal lobe

Psycholinguistic research on temporal lobe epilepsy has identified deficits in lexical access to stored word knowledge, often showing difficulties with impaired naming, impaired verbal fluency, and slower processing time in semantic category decision tasks. This study presents the neuroanatomical correlates of dissociative lexical–semantic impairments in medial temporal lobe epilepsy in both dominant and non–dominant hemispheres. Clinical subjects demonstrated the same accuracy in lexical–semantic processing tasks as healthy participants, but significantly slower lexical–semantic processing compared to the control group. Further analysis showed that a lesion in the medial temporal lobe of the dominant hemisphere caused category–specific deficits, while a lesion in the non–dominant temporal lobe did not cause impairments. The results suggest that epilepsy of the medial temporal lobe can cause impaired lexical–semantic access, leading to disproportionate damage to certain lexical–semantic categories. The confirmed assumptions of this research are consistent with neuroanatomical models that show that hemispheric differences in the epileptic focus can affect the processing of certain lexical–semantic categories, disrupt certain lexical–semantic categories, and influence the reorganization of the language system.