Localization of cortical dysfunction based on auditory and visual naming performance.

Abstract

Naming is generally considered a left-hemisphere function without precise localization. However, recent cortical stimulation studies demonstrate a modality-related anatomical dissociation, in that anterior temporal stimulation disrupts auditory description naming ("auditory naming") but not visual object naming ("visual naming"), whereas posterior temporal stimulation disrupts naming on both tasks. We hypothesized that patients with anterior temporal abnormalities would exhibit impaired auditory naming, yet normal range visual naming, whereas patients with posterior temporal abnormalities would exhibit impaired performance on both tasks. Thirty-four patients with documented anterior temporal abnormalities and 14 patients with documented posterior temporal abnormalities received both naming tests. As hypothesized, patients with anterior temporal abnormalities demonstrated impaired auditory naming, yet normal range visual naming performance. Patients with posterior temporal abnormalities were impaired in visual naming; however, auditory naming scores were intact. Although these group patterns were statistically significant, on an individual basis, auditory-visual naming asymmetries better predicted whether individual patients had anterior or posterior temporal abnormalities. These behavioral findings are generally consistent with stimulation results, suggesting that modality specificity is inherent in the organization of language, with predictable neuroanatomical correlates. Results also carry clinical implications regarding localizing dysfunction, identifying and characterizing naming deficits, and potentially, in treating neurologically based language disorders.