Abstracts

Rationale: Results from stimulation-based language mapping suggest considerable inter-individual variability in the number of naming sites identified in the left (language dominant) perisylvian region. Some of this variability has been shown to be related to patient characteristics, including level of language proficiency, intelligence, degree of language lateralization, presence of medial temporal sclerosis (MTS) and presence of space-occupying lesions. Findings suggest that relatively disadvantaged groups (i.e., MTS, less proficient language in bilingualism) tend to exhibit spatially, more extensive naming areas. Given this pattern, together with well established findings of reduced naming ability with increasing age, we hypothesized that increasing age would be associated with a greater number of naming sites. Methods: Subjects were 42 pharmacologically intractable, left (language dominant) TLE patients (mean age = 31.6, SD = 12.4; range = 8 - 64) who underwent pre-resection cortical language mapping 15 intraoperative, 27 extraoperative) utilizing visual and auditory naming tasks. A mean of 26 cortical sites per patient was tested (range: 15-55), depending on time constraints (intraoperative) or extent of implantation (extraoperative). Prior to stimulation mapping, 36 patients underwent extensive preoperative assessment of naming including Columbia Auditory and Visual Naming, and Boston Naming tests. Pearson correlations were used to assess the relation between chronological age and number of auditory and visual naming sites, and to determine whether number of naming sites was related to other, potentially relevant, patient variables, including age of seizure onset, intelligence, education level, and preoperative naming performance. Results: Consistent with our hypothesis, increasing age was associated with a greater number of visual naming sites (r = .46, P = .002); however, only a weak relation was found between age and number of auditory naming sites (r = .28, P = .08). Number of naming sites was not correlated with age of seizure onset, education, or IQ. Consistent with previously reported patterns, a greater number of auditory naming sites was associated with poorer preoperative auditory naming accuracy scores (r = -.39, P = .02). Number of visual naming sites did not correlate with naming performance. Conclusions: Results suggest that number of visual naming sites increases with increasing age. Given the absence of a correlation between age and naming performance in this sample, perhaps a broader cortical region is required to maintain naming abilities with increasing age. An alternative explanation might be that an increase in positive naming sites may represent greater susceptibility to naming disruption with age.