What happens in the human brain just before a word is spoken? | Gdańsk University of Technology

In a fraction of a second before we recall a word, even one as simple as ‘apple’ or ‘house’, highly complex cognitive processes take place in the brain. This is when different areas of the brain work together to locate and reconstruct the correct information. This process involves combining scattered fragments of memory, such as the meaning of a word, its sound or associations, into a single coherent whole. This makes it possible to quickly and effectively recall a specific memory or concept.

“In our new study, just published in Nature Communications, we show how the partial integration of information affects memory and cognitive functions. Thanks to remarkable recordings from inside a living human brain, we are beginning to understand exactly how this communication takes place on a large scale,” said Michał Kucewicz, PhD, DSc, Professor at Gdańsk Tech and Head of the Brain and Mind Electrophysiology Laboratory at the Gdańsk Tech BioTechMed Centre.

The team focused on people with drug-resistant epilepsy. Electrodes were implanted in the patients to locate the sources of their seizures, which provided a unique opportunity to record brain activity during everyday mental tasks.

During the study, patients performed memory tasks using simple nouns.

“The data reveal something remarkable: fast brain waves (known as high-frequency oscillations, or HFOs) appear simultaneously in the sensory and associational areas of the brain when memories are encoded and recalled,” explained Prof. Kucewicz.

Our researchers have observed that recalling even the simplest word is not merely a small, local event, but a global phenomenon. When reproducing information, synchronised activity occurs across approximately half of all recorded brain areas. This synchronised brain activity links sensory areas, such as vision, with higher-order cognitive areas across all five lobes of the cerebral cortex.

What is more, when recalling a word spontaneously, the likelihood of these coordinated bursts occurring rises sharply around 300 milliseconds before the person begins to speak, peaking just before they start to utter the word. It is like watching the brain preparing to share a thought.

Neural connections in the brain are triggered in an ordered, cascading sequence, with one network activating another – as the brain decodes a word and the associated concepts. This cascade of global brain synchronisation may be the mechanism that triggers successive concepts in the course of thinking or the stream of consciousness.

The research described in the article is the result of the HFO-MEMO project, funded by an Opus LAP grant from the National Science Centre awarded to Michał Kucewicz, PhD, DSc, in collaboration with researchers from the Wrocław Medical University and St. Anne's University Hospital in Brno.

The co-authors of the paper are researchers from the Department of Multimedia Systems at Gdańsk Tech: Prof. Andrzej Czyżewski; Michał Kucewicz, PhD, DSc, Professor at Gdańsk Tech; Jesus Garcia-Salinas, PhD; and doctoral students Sathwik Prathapagiri and Marina Skierkowska (Galanina).

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About Nature Communications

Nature Communications is the flagship open-access journal of the Nature Publishing Group, a peer-reviewed British science weekly founded in 1869 by Norman Lockyer, currently published by Springer Nature. It publishes groundbreaking research covering all fields of the natural sciences, and its articles are among the most highly cited papers in the world. Similar to Nature itself or its American counterpart, Science, the journal ranks among the leading journals with the highest impact factor.