Scientists discover how the brain…

Houston, TX - Jun 9, 2026

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Researchers at Baylor College of Medicine have uncovered a fundamental principle underlying how the human brain processes meaning across multiple languages. In a new study published in Cell, scientists recorded the activity of individual neurons in the human hippocampus and found that bilingual people appear to organize concepts in a shared neural structure - even when speaking entirely different languages.

The findings provide one of the most detailed looks yet at how the brain supports bilingualism and may help explain how people can effortlessly translate thoughts between languages without confusing them.

The Baylor investigators studied four fully bilingual English-Spanish speakers undergoing neurosurgical procedures for epilepsy treatment. Using ultra-high-resolution recording technologies, including microelectrodes and Neuropixels probes, the researchers measured the activity of hundreds of individual neurons in the hippocampus while participants listened to stories, read phrases aloud and engaged in spontaneous conversations in both English and Spanish.

The team discovered that although most individual neurons responded differently in English versus Spanish, the overall geometric organization of meaning in the brain remained remarkably consistent across languages. Words with related meanings, such as "cat" and "dog," occupied similar relative positions in neural space regardless of whether they were heard in English or Spanish.

"Our findings suggest that the brain may store meaning in a language-independent format," said Dr. Sameer Sheth, professor of neurosurgery, McNair Scholar and Cullen Foundation endowed chair at Baylor College of Medicine and co-senior author of the study. "Different languages appear to access a shared conceptual map rather than creating entirely separate representations of the world."

The researchers describe this phenomenon as a "shared semantic geometry." Instead of using identical neurons for each language, the brain appears to preserve the relationships between concepts across languages while allowing each language to use its own neural "readout axes."

"This helps explain how bilingual people can switch between languages so fluidly," said Dr. Benjamin Hayden, professor of neurosurgery and McNair Scholar at Baylor and co-senior author of the study. "The brain seems to maintain a common internal structure for meaning while simultaneously keeping languages distinct enough to avoid interference."

The work also revealed a small group of neurons that responded similarly to translation-equivalent words such as "earth" and "tierra." The researchers termed these "cross-language neurons." However, these cells alone could not explain bilingual language processing. Even when those neurons were removed from analyses, the broader shared neural geometry remained intact.

The findings suggest that translation is not driven primarily by specialized "dictionary neurons," but instead emerges from coordinated activity across large neural populations.

Sheth explained the results with this piano analogy: "If each neuron were a piano key, then hearing the same phrase in different languages is like playing the same song in different musical keys. The two renditions of the song require depressing different piano keys, but the relative pattern between the successive notes is the same in the two versions, as one is a transposition of the other. In the same way, the activity of any single neuron differs when one is listening to the same phrase in different languages, but the pattern of activity ('geometry') across the population of neurons is the same."

"Our results show that bilingual meaning is an emergent property of neural populations," said lead author Xinyuan Yan, postdoctoral scholar. "The brain does not appear to rely on one-to-one translation cells. Instead, it preserves patterns of relationships among concepts across languages."

To analyze the neural data, the researchers compared human brain activity to multilingual artificial intelligence language models, including multilingual BERT (mBERT). They found striking similarities between the geometry of semantic representations in the hippocampus and the internal organization of modern AI systems trained on multiple languages.

"Large language models and the human brain may be converging on similar computational solutions for representing meaning," Hayden said. "That does not mean AI works exactly like the brain, but it suggests there may be universal principles for organizing knowledge."

The hippocampus, a structure traditionally associated with memory, historically has not been considered a major language region because it is difficult to study using standard brain imaging techniques. However, recent work from the same research group has increasingly implicated the hippocampus in representing the meanings of words and concepts.

The new study extends those findings by showing that hippocampal neurons organize meaning in a way that transcends any single language.

Beyond advancing basic neuroscience, the findings eventually could influence the development of brain-computer interfaces, language rehabilitation therapies, and future AI systems designed to communicate more naturally with humans.

The researchers caution that the study involved only four participants, all of whom were English-Spanish bilinguals undergoing epilepsy treatment. "The next question is whether this shared geometry is something we're born with or something that emerges as we learn a second language - and whether it looks the same for languages as different from each other as, say, English and Mandarin," said Yan. Future studies will be needed to determine whether the same neural principles apply to other languages and larger populations.

Still, the results provide an unprecedented glimpse into one of the defining features of human cognition: the ability to express the same thought in multiple languages.

"Humans can seamlessly translate ideas between languages because the brain appears to preserve the structure of meaning itself," said Sheth, who also is director of the Gordon and Mary Cain Pediatric Neurology Research Foundation Labs at Texas Children's Hospital. "What changes is not the underlying concept, but the neural pathway used to express it."

This project was funded in part by the National Institutes of Health BRAIN Initiative (U01 NS121472), the McNair Foundation, and the Gordon and Mary Cain Pediatric Neurology Research Foundation.