Black-capped Chickadee (Poecil atricapillus) This small passerine bird from North America, which lives in deciduous and mixed forests, has an extraordinary memory that allows it to remember thousands of food locations to help it survive the winter. Now, scientists Columbia University Zuckerman Institute for Mind, Brain, and Behavior have discovered how Gala is able to remember so many details. They memorize the location of each food item using brain cell activity similar to a barcode.
Chetty other. We propose that animals recall episodic memories by reactivating barcodes in the hippocampus.Image credit: Chetty other., doi: 10.1016/j.cell.2024.02.032.
“We found that each memory is tagged with a unique pattern of activity in the hippocampus, the part of the brain that stores memories,” said Dr. Dmitry Aronov, senior author of the study.
“We called these patterns 'barcodes' because they are very specific labels for individual memories. For example, the barcodes of two different caches are Even if two caches are next to each other, there is no correlation.
“There are a number of human discoveries that perfectly match the barcode mechanism,” added Dr. Selman Chetty, lead author of the study.
Scientists have known for decades that the brain's hippocampus is necessary for episodic memories, but understanding exactly how those memories are encoded has been much more difficult. was.
Part of the reason is that it's often difficult to know what animals remember at any given time.
To get around this problem in the new study, Dr. Aronoff and colleagues turned to the black-capped chickadee.
Researchers found that chickadees provide a unique opportunity to study episodic memory because they hide food and then have to remember to come back to retrieve it later.
“Each cache is a clear, obvious, easily observable moment in which a new memory is formed,” Dr. Aronoff said.
“By focusing on these special moments, we were able to identify patterns of memory-related activity that we had not noticed before.”
The researchers needed to design an arena that could automatically track the detailed behavior of the gulls as they hide and retrieve food.
They also needed to develop techniques to make large-scale, high-density neural recordings inside the birds' brains as they move freely.
Their brain recordings during caching revealed very sparse and transient barcode-like firing patterns across hippocampal neurons. Each barcode contains only about 7% of the cells in the hippocampus.
“When a bird creates a cache, about 7% of its neurons respond to that cache. When the bird creates another cache, another group of 7% of its neurons responds,” Dr. Aronoff said. Ta.
These neural barcodes occurred simultaneously with the conventional activity of neurons in the brain that are triggered in response to specific locations, aptly called place cells.
Interestingly, however, there were no similarities in the episodic memory barcodes of cache locations close to each other.
“It was widely thought that place cells change when animals form new memories,” Dr. Aronoff says.
“For example, placement cell firings may increase or decrease near the cache location.”
“This was a common hypothesis, but our data did not support it.”
“Place cells do not represent information about caches; rather, they appear to remain relatively stable as the chickadees cache and retrieve food from the environment.”
“Instead, episodic memory is represented by additional activity patterns, or barcodes, that coexist with place cells.”
The authors liken the newly discovered hippocampal barcode to a computer hash code, a pattern that is assigned as a unique identifier to different events.
They suggest that barcode-like patterns may be a mechanism for the rapid formation and storage of many non-interfering memories.
“Perhaps the biggest unanswered question is whether and how the brain uses barcodes to prompt behavior,” Dr. Aronoff said.
“For example, it's not clear whether chickadees activate barcodes and use their memory of food-caching events when deciding where to go next.”
“We plan to address these questions in future studies through more complex settings in the laboratory, recording brain activity while the birds choose which food stores to visit.”
“If you plan on retrieving cached items before you actually retrieve them, that's to be expected,” Dr. Chetty said.
“We wanted to identify the moments when a bird is thinking about a location but haven't gotten there yet, and see if activating the barcode might move the bird to the cache. thinking about.”
“We also want to know whether the barcoding tactics they discovered in chickadees are widely used among other animals, including humans. It might help clarify the core.”
“When you think about how people define themselves, who they think they are, their sense of self, episodic memories of specific events are central to that. That's what we're trying to understand. That is what we are doing.”
a paper The survey results were published in a magazine cell.
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Selman N. Chetty other. Barcoding of episodic memory in the hippocampus of food-storing birds. cell, published online March 29, 2024. doi: 10.1016/j.cell.2024.02.032
Source: www.sci.news
