Comprehension and production of nouns and verbs in temporal lobe epilepsy.

Previous research on linguistic performance at the single-word level in patients with temporal lobe epilepsy (TLE) has mostly been limited to the comprehension and production of nouns, and findings have been inconsistent. Results are likewise limited and controversial regarding the lateralization of the epileptogenic focus. The present study investigates comprehension and production of nouns and verbs in patients with left and right TLE (12 in each group). We designed a comprehension (word-picture matching) test and a production (naming) test, matched on a range of psycholinguistic parameters for the two word classes. The results showed impaired verb comprehension in patients with left TLE and impaired noun and verb production in both groups of patients compared to the control group. Patients with left and right TLE differed significantly on verb comprehension and noun production, whereas verb production was equally impaired in the two groups of patients. These findings suggest difficulties with single-word processing in patients with both left and right TLE, which are more prominent for verbs than for nouns in patients with left TLE. The verb production (action naming) test turned out to be the most effective tool for assessing linguistic difficulties at the single-word level in patients with TLE.