Are the ventral anterior temporal lobes involved in accessing conceptual knowledge during spoken word production? fMRI evidence from auditory naming

Abstract

There is ongoing debate about the role of ventral anterior temporal lobe (vATL) regions in the initial stages of production, particularly in accessing conceptual knowledge, with most evidence coming from visual naming tasks. Here, we investigated whether these regions are engaged during naming from different types of auditory stimuli. Twenty-five participants completed an fMRI experiment involving two naming tasks: auditory sentence definition (e.g., The yellow part of an egg) and nonverbal environmental sound (e.g., a sheep bleating). Our overall aim was to identify brain regions that are commonly activated across both naming tasks as well as those showing task-specific activations. With regards to the vATL's role, we hypothesised that these regions would show common activation across naming tasks, consistent with their proposed role in crossmodal conceptual processing, one of the first processing stages for retrieving a word based on an external input. Left-lateralized activation common to both tasks was observed in posterior fusiform gyrus, superior temporal gyrus and sulcus, inferior and superior frontal gyrus, and subcortical and cerebellar regions. Significant activation was observed in the bilateral vATLs only during naming to definitions, despite tSNR being equivalent across tasks. Our findings indicate that environmental sounds do not activate the vATL to the same extent as auditory definitions, placing constraints on the crossmodal nature of semantic representations in these regions.