How your brain subconsciously recognizes everyday patterns: Insights into automatic thought processes

How your brain subconsciously recognizes everyday patterns: Insights into automatic thought processes

The human brain constantly recognizes patterns in everyday experiences, and it can do this without conscious thinking, like a study 1 shows. This research analyzed the neural activity of people who had electrodes implanted in their brains for medical reasons.

The study shows that neurons in key brain regions combine information about what is happening and when it is happening. This allows the brain to recognize the patterns of events over time. This helps the brain predict upcoming events, the authors say. The results were published today in the journalNaturepublished.

“The brain does a lot of things that we are not aware of,” explains Edvard Moser, a neuroscientist at the Norwegian University of Science and Technology in Trondheim. “This is no exception.”

An excess of data

To understand the world around us, the brain must process a flood of information: what is happening, where it is happening, and when it is happening. The study authors wanted to examine how the brain organizes this information over time - a crucial step in Learning and memory.

The research team studied 17 People with epilepsy who were preparing for surgical treatment. These electrodes allowed the authors to directly record the activity of individual neurons in multiple brain regions.

These regions included the Hippocampus and the entorhinal cortex, those on memory and the navigation are involved. These areas contain time and place cells, which act as the body's internal clock and GPS system by encoding time and locations. “All external information that enters our brain must be filtered through this system,” says Itzhak Fried, study co-author and neurologist at the University of California, Los Angeles.

Parade of faces

To prepare for the main experiment, the researchers showed each participant a variety of images of faces. For each participant, the scientists identified six Faces that strongly activated a single neuron in the participant's brain. For example, a participant might have a 'man in sunglasses' neuron as well as a 'woman in hat' neuron and four others, each preferring a particular face.

The team arranged each participant's six pictures in a triangle, with one picture on each corner and another picture on each side. Each image was connected by lines that crossed the sides of the triangle and its interior.

In an experimental trial, participants viewed a series of facial images. A simple rule dictated the order of the images: each face was followed by another face connected to it in a triangle (see 'Pattern Recognition'). For example, if the first face was the one at the bottom left corner of the triangle, the second face would be one of its two immediate neighbors: the face at the center of the base of the triangle or the face at the center of the left side of the triangle. The experimenters did not disclose this rule to the participants. In addition, participants were distracted by being asked questions about the content of the images during each trial.

During the experiment, neurons in each participant's hippocampus and entorhinal cortex gradually began to respond not only to the presented face, but also to faces directly connected to it in the triangle. When participants were asked if they had noticed a pattern in the order of the images, they said they had not. Nevertheless, their brain cells learned the pattern, showing that the brain can recognize patterns without conscious awareness. In the breaks between trials, the participants' 'face' neurons played back what they had learned and went through the patterns independently without being stimulated.

"This is something that is not explicit, but implicit. And the brain essentially detects it very quickly, and we can observe these changes in individual cells," says Fried.

Future-oriented neurons

The authors found that the neurons could also anticipate which images would appear next. This suggests that the brain learns to predict future events based on learned patterns.

“The fact that this happens without external incentives is really interesting,” says Matt Jones, a neuroscientist at the University of Bristol, UK. “Many of the results are remarkably consistent with predictions from rodent research and highlight how hippocampal circuits have evolved to structure our cognitive maps,” he adds.

Understanding how the brain organizes information about sequences of events could have important clinical applications. For example, you could Memory Enhancement Therapies aim to promote specific neural patterns that represent important memories, explains Fried. "It's ultimately about connecting things together in time. That's really the essence of memory."

1. Tacikowski, P., Calendar, G., Ciliberti, D. & Fried, I. Nature https://doi.org/10.1038/s41586-024-07973-1 (2024).

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