This study uses ultrahigh-density Neuropixels recordings in humans to identify neurons in the language-dominant prefrontal cortex that encode detailed information about the phonetic arrangement and composition of planned words during speech production. These neurons represent the order and structure of articulatory events before utterance, reflecting syllabic segmentation. They accurately predict phonetic, syllabic, and morphological components of upcoming words and exhibit a temporally ordered dynamic. The findings reveal a structured organization and encoding cascade of phonetic representations by prefrontal neurons, demonstrating a cellular process supporting speech production and distinguishing between speech production and perception.

Arjun R. Khanna, William Muñoz, Young Joon Kim, Yoav Kfir, Angelique C. Paulk, Mohsen Jamali, Jing Cai, Martina L. Mustroph, Irene Caprara, Richard Hardstone, Mackenna Mejdell, Domokos Meszéna, Abigail Zuckerman, Jeffrey Schweitzer, Sydney Cash, Ziv M. Williams