Abstracts

Cortical stimulation studies indicate considerable inter-individual variability in the location and number of visual naming sites in the left (language dominant) perisylvian region. Some of this variability has been shown to be attributable to gender, level of language proficiency, intelligence, and degree of language lateralization. Aside from gender, the general pattern is that lower level of functioning (i.e., lower IQ, less proficient language in bilingualism) is associated with more extensive naming areas. As some studies show that patients with MTS perform more poorly on naming tests, we hypothesized that MTS patients would exhibit a greater number or more widespread location of both auditory and visual naming sites. Subjects were 36 left TLE patients (10 MTS, 26 nonMTS) who underwent pre-resection cortical language mapping (17 intraoperative, 19 extraoperative) with visual and auditory naming tasks. A mean of 22 sites per patient were tested (range: 8-46), depending on time constraints (intraoperative) or extent of implantation (extraoperative). Independent samples t tests were used to compare the number of auditory and visual naming sites identified in MTS vs. nonMTS patients, and to compare these groups with respect to preoperative auditory and visual naming scores, IQ, age at surgery and age of seizure onset. Fisher[apos]s exact test was used to assess gender distribution between groups. Pearson correlations were used to assess the relation between number of naming sites and subjective word finding difficulty. Both MTS and nonMTS patients exhibited auditory naming sites anterior to visual naming sites (auditory naming was also disrupted at most [ldquo]visual[rdquo] naming sites), consistent with previous findings. Additionally, both groups showed similar topographical patterns overall, with most positive naming sites scattered along the superior and middle temporal gyri. Although the number of visual naming sites was comparable between groups (MTS: mean = 1.9, SD = 1.4; nonMTS: mean = 1.0, SD = 1.4; p = .12), a significantly greater number of auditory naming sites were identified in MTS (mean = 1.7, SD = 1.2) than in nonMTS patients (mean = .52, SD = .82; p = .002). There were no significant group differences in preoperative auditory or visual naming performance, age at surgery, age of seizure onset, IQ, or gender. Number of auditory, but not visual, naming sites correlated significantly with subjective word finding difficulty (r = .39, p = .02). The overall location of naming sites and number of visual naming sites were similar between groups; however, MTS patients, as a group, exhibited a greater number of auditory naming sites. As there were no differences between MTS and nonMTS patients in naming performance, perhaps, more cortex might be needed to support a comparable level of performance in the MTS group. The involvement of more cortical sites might also be related to the subjective sense of increased level of effort. (Supported by NIH R01NS35140.)