Emergence of Language in the Developing Brain

TL;DR

This study investigates how language representations develop in the human brain from childhood to adulthood using neural recordings and compares these developmental patterns with large language models, revealing parallels in language acquisition.

Contribution

It demonstrates that language representations evolve with age in the brain and that large language models can spontaneously capture adult-like neural representations.

Findings

Language features are represented across the cortex from age 2.

Slower word-level representations emerge in older individuals.

Large language models develop representations similar to adult brain patterns.

Abstract

A few million words suffice for children to acquire language. Yet, the brain mechanisms underlying this unique ability remain poorly understood. To address this issue, we investigate neural activity recorded from over 7,400 electrodes implanted in the brains of 46 children, teenagers, and adults for epilepsy monitoring, as they listened to an audiobook version of "The Little Prince". We then train neural encoding and decoding models using representations, derived either from linguistic theory or from large language models, to map the location, dynamics and development of the language hierarchy in the brain. We find that a broad range of linguistic features is robustly represented across the cortex, even in 2-5-year-olds. Crucially, these representations evolve with age: while fast phonetic features are already present in the superior temporal gyrus of the youngest individuals, slower word-level representations only emerge in the associative cortices of older individuals. Remarkably, this neuro-developmental trajectory is spontaneously captured by large language models: with training, these AI models learned representations that can only be identified in the adult human brain. Together, these findings reveal the maturation of language representations in the developing brain and show that modern AI systems provide a promising tool to model the neural bases of language acquisition.