Human precentral gyrus neurons link speech sequences from listening to speaking

Speech perception and production are interconnected processes, but the underlying neural mechanisms remain unclear. We investigated this relationship by recording large-scale single-neuron activity in the human brain during a delayed sentence repetition task. Contrary to the traditional view that the precentral gyrus is solely responsible for motor execution, we found that neurons there encoded activity across all task phases of listening, delay, initiation, and speaking. Notably, we discovered "mirror" neurons that activated transiently after hearing and before producing specific speech sounds, and "bridge" neurons that maintained activity between the same speech elements during listening and speaking. Population analysis revealed distinct latent components for each task phase and persistent dynamics for specific sentences. Overall, this study provides novel insights into the neuronal basis of speech processing, emphasizing the intricate interplay between perception, production, and verbal working memory.