Congruent brain signatures specific to speech sounds in fronto-temporal cortex during language production and understanding.
In this fMRI study we investigated whether language production and understanding recruit the same phoneme-specific networks. We did so by comparing the brains response to different phoneme categories in minimal pairs: Bilabial-initial words (e.g., monkey) were contrasted to alveolar-initial words (e.g., donkey) in 37 participants performing both language production and comprehension tasks. Region-of-Interest analyses showed that the same sensorimotor networks were activated across the language modalities. In motor regions, word production and comprehension elicited the same phoneme-specific topographical activity patterns, with stronger haemodynamic activations for alveolar-initial words in the tongue cortex and stronger activations for bilabial-initial words in the lip cortex. In the posterior and middle superior temporal cortex, production and comprehension likewise resulted in similar activity patterns, with enhanced activations to alveolar-compared to bilabial-initial words. These results disagree with the classical separation between language production and understanding in neurobiological models of language, and instead advocate for a cortical organization where the same phoneme-specific acoustic-and-articulatory representations carry production and comprehension.