Abstracts

Rationale: Numerous studies have shown that left anterior temporal lobectomy (ATL) is associated with changes in visual object naming (e.g., Hermann et al., 1999). In contrast, few studies have examined the effects of left ATL on changes in auditory definition naming or on category specific definition naming (living vs nonliving or common vs proper noun naming). According to prior claims that the left temporal pole is specialized for retrieval of unique entity concepts, one might expect proper noun naming to be most sensitive to decline with left ATL. The present study examines both visual object and auditory definition naming declines in a large group of patients tested before and after left ATL. Hypothesis:  Declines will occur in both visual object and auditory definition naming in keeping with previous research, with the greatest decline in auditory definition naming for proper nouns. Methods: Participants were 52 left temporal lobe epilepsy patients tested prior to and six months following left ATL with the Boston Naming Test (BNT) and the Auditory Definition Naming (ADN) Test (Hammeke, Kortenkamp, Binder, 2005). Visual object naming involves naming in response to a visual line drawing. Auditory definition naming requires naming in response to a verbal description (e.g., "jewelry for the finger"). Categories for ADN included common living (CL) (e.g., snail), common nonliving (CN) (e.g., ring), unique living (UL) (e.g., Obama), and unique nonliving (UN) (e.g., Greece). Repeated measures ANOVA was conducted to examine the effects of surgery on performance, with follow-up analyses to elucidate the significant main and interaction effects. To examine simple effects, change scores were calculated by subtracting the pre- from the post-operative raw score, and mean percent change scores were calculated by dividing the change score by the pre-operative raw score.  Results: Repeated measures ANOVA showed a significant main effect of surgery on performance (p=.0001). Significant declines were observed across both naming tasks and all categories (p<.05). A significant interaction was seen between time (pre- to post-operative) and condition (ADN category). Paired t-tests showed significantly greater decline for the proper living (UL) category (mean -18.9%) relative to all other categories (all ps<.001) with no significant difference among the remaining categories (figure). BNT percent change (mean -17.7%) was significantly greater (p<.0001) than all ADN categories except proper living nouns. Conclusions: Left ATL results in significant declines for both visual object and auditory definition naming. Definition naming declines were much greater for proper living (famous people) concepts than for proper nonliving (place name) concepts, suggesting that the deficit is not specific to unique entity concepts per se. This pattern suggests instead that the left ATL plays a central role in storing knowledge about specific people, consistent with claims for a role of the temporal pole in processing social concepts and faces.  The proposed role of the anterior ventral visual system in visual naming over auditory naming may explain the decline on BNT. Funding: NINDS RO1 NS35929