Vol. 14, No. 4
On the Role of the Anterior Superior Temporal Lobe in Language Processing: Hints from Functional Neuroimaging Studies
Joint Doctoral Program in Language and Communicative Disorders, SDSU & UCSD
A number of functional neuroimaging studies have reported activation in the left anterior superior temporal lobe (aSTL), encompassing the cortex of the anterior superior temporal gyrus and sulcus, in response to various linguistic stimuli. In this paper, I review these studies in order to explore the possible contribution of the aSTL to language processing. A specialization of the aSTL for sentence processing is unlikely, as activation in this area is not only elicited by sentences, but also by words, syllables, and even nonlinguistic auditory stimuli. It seems, however, that the aSTL responds more strongly to sentences than to other speech stimuli, and that the anterior superior temporal sulcus in particular is more responsive to speech than to other types of sound. As an alternative to a language-specific account, I suggest that the aSTL can be regarded as sensory association cortex that underlies the analysis of complex acoustic features, especially those that are typical for speech. The efficient completion of this sensory analysis is particularly critical when stimulus complexity and processing demands increase. Consequently, the amount of aSTL activation grows, as more difficult tasks have to be performed on auditory or linguistic stimuli.