Brain cells map the building blocks of speech

A Nature study used temporarily implanted brain electrodes in epilepsy patients to observe real-time single-neuron activity in the frontotemporal cortex as people spoke. It found specialized neurons that encode parts of speech and semantics or syntax, with many neurons firing just before specific components (e.g., nouns) are spoken. The left hemisphere showed greater involvement, and the researchers noted that both brain activity and large-language models track the sentence context up to about five preceding words to shape the next word—supporting a modular view of language built from neuronal building blocks.