From Thought to Action: How a Hierarchy of Neural Dynamics Supports Language Production

TL;DR

This study uses MEG and EEG to reveal a hierarchical neural dynamic in the brain during language production, showing how different linguistic levels are sequentially activated and maintained over time.

Contribution

It provides the first detailed neurophysiological evidence supporting hierarchical models of language production using non-invasive brain imaging.

Findings

Neural activity shows sequential activation of linguistic levels

Neural representations are maintained over long periods within each level

Supports hierarchical neural coding in language production

Abstract

Humans effortlessly communicate their thoughts through intricate sequences of motor actions. Yet, the neural processes that coordinate language production remain largely unknown, in part because speech artifacts limit the use of neuroimaging. To elucidate the unfolding of language production in the brain, we investigate with magnetoencephalography (MEG) and electroencephalography (EEG) the neurophysiological activity of 35 skilled typists, while they typed sentences on a keyboard. This approach confirms the hierarchical predictions of linguistic theories: the neural activity preceding the production of each word is marked by the sequential rise and fall of context-, word-, syllable-, and letter-level representations. Remarkably, each of these neural representations is maintained over long time periods within each level of the language hierarchy. This phenomenon results in a superposition of successive representations that is supported by a hierarchy of dynamic neural codes. Overall, these findings provide a precise computational breakdown of the neural dynamics that coordinate the production of language in the human brain.