The human brain works backwards to recover memories.



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When we remember a past event, the human brain reconstructs that experience in reverse order, according to a new study at the University of Birmingham.

Understanding more precisely how the brain retrieves information could help us better badess the reliability of eyewitness testimony, for example, crime scenes, where people can often remember the general "essence" of an event, but remember details specific visuals less reliably.

The study, published in Communications of nature, was performed by researchers at the Center for Human Brain Health, which reconstructed the process of memory recovery, using techniques of brain decoding. These techniques make it possible to track when, in time, a single memory in the brain is being reactivated.

They discovered that, when retrieving information about a visual object, the brain focuses first on the central meaning, recovering the "essence", and only later recalls more specific details.

This contrasts sharply with how the brain processes images when it first encounters them. When we initially see a complex object, the first thing we notice are the visual details (patterns and colors). The abstract and meaningful information that tells us the nature of the object we are seeing, be it a dog, a guitar or a cup, for example, comes later.

"We know that our memories are not exact replicas of the things we originally experienced," says Juan Linde Domingo, lead author of the study. "Memory is a reconstructive process, biased by personal knowledge and visions of the world, sometimes we even remember events that never really happened, but exactly how memories are reconstructed in the brain, step by step, currently not well understood" .

During the study, participants saw images of specific objects and then learned to badociate each image with a single reminder word, for example, the word & # 39; rotate & # 39; or & # 39; throw away & # 39; Later, the participants were presented with the reminder word and asked to reconstruct the badociated image in as much detail as possible.

Brain activity was recorded throughout the task using 128 electrodes connected to the scalp, which allowed researchers to observe changes in brain patterns with millisecond accuracy. Finally, the researchers trained a computer algorithm to decode what type of image the participant was recovering at different points in the task.

"We were able to show that the participants were retrieving abstract information at a higher level, as if they were thinking of an animal or an inanimate object, shortly after hearing the reminder word," explains Maria Wimber, the study's lead author. .

"Only later did they retrieve the specific details, for example, if they had been looking at a colored object or a black and white outline."

"If our memories prioritize conceptual information, this also has consequences on how our memories change when we recover them repeatedly," Linde Domingo adds.

"It suggests that they will become more abstract and more meaningful with each recovery, although our memories seem to appear in our inner eye as vivid images, they are not mere snapshots of the past, but reconstructed and skewed representations."

Follow-up studies should check whether this inverted reconstruction cascade is "connected" in the brain. If so, the sequence of reconstruction should remain stable under different conditions, even when a person, for example, consciously concentrates his attention on specific details during learning.

Currently, the team is also studying in more detail how and where the brain reconstructs the most complex memories. Once the route of memory recovery in the healthy brain is established, researchers can also begin to badyze how it is altered in healthy aging, or how this route could contribute to the general generalization of memories in diseases such as Post-traumatic stress disorder.


Why do two people see the same thing but have different memories?


More information:
Linde-Domingo and Wimber et al (2019) & # 39; Evidence that the flow of neuronal information is reversed between the perception of the object and the reconstruction of the object of memory & # 39; Communications of nature

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The human brain works backwards to recover memories (2019, January 14)
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