Black-capped chickadees (Poecile atricapillus), small North American passerine birds that live in deciduous and mixed forests, have extraordinary memories that can recall the locations of thousands of morsels of food to help them survive the winter. Now, scientists at Columbia University’s Zuckerman Mind Brain Behavior Institute have discovered how the chickadees can remember so many details: they memorize each food location using brain cell activity akin to a barcode.
“We find that each memory is tagged with a unique pattern of activity in the hippocampus, the part of the brain that stores memories,” said Dr. Dmitriy Aronov, senior author of the study.
“We called these patterns ‘barcodes’ because they are extremely specific labels of individual memories — for example, barcodes of two different caches are uncorrelated even if those two caches are right next to each other.”
“There are many findings in humans that are totally consistent with a barcode mechanism,” added Dr. Selmaan Chettih, first author of the study.
Scientists have known for decades that the hippocampus of the brain is required for episodic memory, but it had been much harder to understand exactly how those memories were encoded.
That’s in part because it’s hard to know in most cases what an animal might be remembering at a particular time.
To get around this problem in the new study, Dr. Aronov and his colleagues looked to chickadees.
They realized chickadees offered a unique opportunity to study episodic memories because the birds cache food items and then must remember to go back for them later.
“Each cache is a well-defined, overt, and easily observable moment in time during which a new memory is formed,” Dr. Aronov said.
“By focusing on these special moments in time, we were able to identify patterns of memory-related activity that had not been noticed before.”
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