Brain “punctuation” discovery: memory of experiences in ripple segments

Scientists determine the key mechanisms of human memory formation by studying brain waves called ripples, which organizes different information episodes. Researchers at the University of Barcelona tracked these high-frequency electrical oscillations in patients watching the BBC Sherlock, revealing how the brain and how memory is stored in real time during continuous experiences.

The study, published in Nature Communications, shows for the first time in humans how ripples-type brain waves coordinate memory encoding. These brief bursts of neural activity, like punctuation, help the ongoing experiences of the brain segments become different and memorable plots.

How ripple organize memory

“These segments mark the meaning of the brain closing an episode in memory and starting recording another episode and starting recording another show,” explains Lluís Fuentemilla, principal investigator at the Institute of Neuroscience, University of Barcelona. “For example, when you do something and receive a call or a doorbell ring, the brain finds that changes occur during the experience, and uses these events as if they were punctuation marks, the full stop in the sentence.”

The researchers monitored the brain activity of ten epilepsy patients who were implanted with electrodes for clinical reasons. When the participants watched the Sherlock episode for 50 minutes, the sensor tracked the ripples—the oscillation lasted about 38 milliseconds, at a frequency of about 90 Hz—about five times per minute in different brain regions.

Revealing two-part memory system

The study found complex coordination between brain regions during memory formation:

• Hippocampus Activities: As the scene changes, ripples on the event boundary increase
• Cortical activity: Ripples occur more in ongoing events rather than in transition
• Temporal cortex: Higher chain rate predicts what events later remember
• Cross-brain coordination: Different regions show complementary timing patterns

The pattern, the researchers said, suggests that the brain region “seems to be a band.” Cortical regions actively process ongoing information, while hippocampus intervenes in the scene “packaging and consolidating” memory changes.

Beyond the laboratory environment

Previous studies have identified ripples in animals, especially mice, but human studies are limited to artificial laboratory tasks. This study breaks a new foundation by studying ripples by reflecting scene changes in real life experiences while naturalistic observations of complex narratives.

Subsequently, participants successfully recalled about 41% of the movie events and maintained the correct sequence order. Importantly, only ripples in the temporal cortex (a region involved in the processing of subjects and people) predict which activities participants will remember later.

Clinical significance

These findings can change understanding of memory disorders and treatments. “To date, when faced with amnesia problems, we consider attention deficits or difficulties in obtaining information,” the researchers noted. “Our results suggest that in these segmentation signals, the way information is structured in the brain may also fail.”

The study opens up possibilities for therapeutic interventions that consider the possibility of how information is organized at the brain level. For older people who exhibit memory disorders, presenting clear pause information between events may promote appropriate coding and storage rather than cognitive pacing, but because structured performance is consistent with the brain’s natural segmentation process.

These insights deepen our understanding of how memory is organized in the human brain and address new avenues for memory-related diseases through natural episodic markers targeting the brain.

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