Both the Middle Temporal Gyrus and the Ventral Anterior Temporal Area Are Crucial for Multimodal Semantic Processing: Distortion-corrected fMRI Evidence for a Double Gradient of Information Convergence in the Temporal Lobes

TLDR

Contemporary semantic memory theories posit that concepts arise from integrating information across distinct sensory and verbal modalities. This study examined the neural basis of that multimodal convergence. Using distortion‑corrected fMRI and a semantic association task, the authors compared activation patterns for verbal and nonverbal versions of the same task to test whether the middle temporal gyrus and ventral anterior temporal lobe serve as convergence sites. Results showed that both MTG and vATL were co‑activated for word and picture semantic tasks, with ROI analyses revealing lateral and longitudinal axes of convergence within the temporal lobe.

Abstract

Abstract Most contemporary theories of semantic memory assume that concepts are formed from the distillation of information arising in distinct sensory and verbal modalities. The neural basis of this distillation or convergence of information was the focus of this study. Specifically, we explored two commonly posed hypotheses: (a) that the human middle temporal gyrus (MTG) provides a crucial semantic interface given the fact that it interposes auditory and visual processing streams and (b) that the anterior temporal region—especially its ventral surface (vATL)—provides a critical region for the multimodal integration of information. By utilizing distortion-corrected fMRI and an established semantic association assessment (commonly used in neuropsychological investigations), we compared the activation patterns observed for both the verbal and nonverbal versions of the same task. The results are consistent with the two hypotheses simultaneously: Both MTG and vATL are activated in common for word and picture semantic processing. Additional planned, ROI analyses show that this result follows from two principal axes of convergence in the temporal lobe: both lateral (toward MTG) and longitudinal (toward the anterior temporal lobe).