Solving an “amnesia” algorithm reveals clues as to how we learn

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Irvine, California, July 6, 2022 – Discovery of how algorithms can learn and retain information more effectively offers a possible understanding of the brain’s ability to absorb new knowledge. The findings of researchers at the University of California, Irvine School of Biological Sciences could help combat cognitive impairments and improve technology. Their study appears in Proceedings of the National Academy of Sciences.

(Link to the open access study: https://www.pnas.org/doi/suppl/10.1073/pnas.2115229119)

The scientists focused on artificial neural networks, known as ANNs, which are algorithms designed to copy the behavior of brain neurons. Like human minds, ANNs can absorb and classify vast amounts of information. Unlike our brains, however, ANNs tend to forget what they already know when fresh knowledge is introduced too quickly, a phenomenon known as catastrophic forgetfulness.

Researchers have long theorized that our ability to learn new concepts stems from the interaction between the brain’s hippocampus and the neocortex. The hippocampus captures fresh information and replays it during rest and sleep. The new cortex captures the new material and revises its existing knowledge so that it can interlace, or layer, the fresh material into similar categories developed from the past.

However, there was some question about this process, considering the excessive time it would take the brain to sort through all the mass of information it gathered during life. This flaw could explain why ANNs lose long-term knowledge when absorbing new data too quickly.

Traditionally, the solution used in in-depth machine learning has been to retrain the network on the entire set of past data, whether or not it was closely related to the new information, a very time-consuming process. The UCI scientists decided to examine the matter in more depth and made a remarkable discovery.

“We found that when ANNs intertwined a much smaller subset of old information, including primarily things that were similar to the new knowledge they had acquired, they learned it without forgetting what they already knew,” said a graduate student. Rajat Saxena, the first author of the paper. . Saxena led the project with assistance from Justin Shobe, an assistant project scientist. Both members of the laboratory of Bruce McNaughton, Distinguished Professor of Neurobiology & Behavior.

“It allowed ANNs to take up-to-date information very effectively, without having to review everything they had previously acquired,” Saxena said. “These findings suggest a brain mechanism for why experts on something can learn new things in that area much faster than non-experts. If the brain already has a cognitive framework related to the new information, the new material can be absorbed faster because changes are needed only in the part of the network of the brain that encodes the faction. ”

The discovery has the potential to address cognitive problems, according to McNaughton. “Understanding the mechanisms behind learning is essential to progress,” he said. “It gives us insights into what happens when brains don’t function as well as they should. We could develop training strategies for people with memory problems of aging or those with brain damage. It could also lead to the ability to manipulate brain circuits so that people can overcome these deficits. ”

The findings offer possibilities also for making algorithms in machines such as medical diagnostic equipment, autonomous cars and many others more accurate and efficient.

Funding for the research was provided by Defense Advanced Research Projects Agency Grant in support of basic research of potential benefit to humanity and by the National Institutes of Health.

About the University of California, Irvine: Founded in 1965, UCI is a member of the prestigious Association of American Universities and is ranked among the top 10 public universities in the nation by American News and World Report. The campus has produced five Nobel laureates and is known for its academic achievement, premier research, innovation and ant mascot. Led by Chancellor Howard Gillman, UCI has more than 36,000 students and offers 224 degree programs. It is located in one of the most secure and economically vibrant communities in the world and is Orange County’s second largest employer, contributing $ 7 billion annually to the local economy and $ 8 billion statewide. For more about UCI, visit www.uci.edu.

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