Abstracts

Rationale: The semantic system is the repository of general knowledge used by many cognitive processes including language, memory, and problem solving. Temporal lobe epilepsy has shown to disrupt the function of the semantic system. The integrity of the semantic system is commonly assessed with naming and category fluency paradigms. Naming tests use both common nouns (e.g., Boston Naming Test) and proper nouns (e.g., Famous Faces); whereas, verbal fluency assessment has generally restricted to generation of words in common noun category (e.g., animals, fruits/vegetables). The objective of the current study is to investigate the sensitivity of common noun and proper noun category fluency tasks using a standardized neuropsychological instrument. We hypothesized that sensitivity of proper noun category fluency would be equivalent to a common noun category fluency. Methods: Participants were epilepsy patients with an electrographically demonstrated unilateral temporal lobe seizure focus (19 right, 22 left). Subjects were right-handed, primary English speakers, age 17 or above and had a full scale IQ above 70. There was no significant difference between the groups with regard to age, education, gender, or age of seizure onset. Delis-Kaplan Executive Function System (DKEFS) Semantic Fluency subtest was administered as part of a pre-surgical comprehensive neuropsychological evaluation. DKEFS semantic fluency subtest measures category fluency for common nouns (animals) and proper nouns (boy’s names). Results: Common noun category fluency was worse in left temporal lobe patients (F=4.296, p<.05) compared to right temporal lobe patients. However, there was no significant difference in proper noun category fluency between the two groups (F=.099, ns). The DKEFS category fluency combines the two list scores to provide a semantic fluency index. The combined semantic fluency index did not significantly differ between the two groups (F=2.023, ns). Conclusions: These findings support that verbal fluency of common noun categories, such as animals, is a sensitive measure of assessing semantic fluency disruption in temporal lobe epilepsy. Interestingly, proper noun fluency did not have the same ability to differentiate between left and right temporal lobe seizure focus. This may be associated to the specific task demand (i.e., a generic category of proper nouns) rather than due to insensitivity of proper nouns. Further study with other categories of proper nouns as well as more specific categories (e.g., names of celebrities, names of family members, city names, etc.) is indicated. Notably, the findings also suggest that the combined semantic fluency index, which is most frequently used in a clinical assessment, was not as sensitive as using the performance on animal fluency alone.