Solving ‘amnesia’ algorithm reveals clues to how we learn

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Irvine, California, July 6, 2022 — A discovery about how algorithms can learn and remember information more efficiently may provide insight into the brain’s ability to absorb new knowledge. The findings of researchers at the University of California, Irvine School of Biological Sciences may help fight cognitive impairment 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, algorithms designed to mimic the behavior of brain neurons. Like the human mind, ANNs can absorb and classify vast amounts of information. Unlike our brains, however, ANNs tend to forget what they already know when new knowledge is introduced too quickly, a phenomenon known as catastrophic forgetting.

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 records and repeats new information during rest and sleep. The neocortex grabs the new material and assesses its existing knowledge so that it can interweave or layer the fresh material into similar categories developed from the past.

However, there are some doubts about this process, given the inordinate amount of time it would take the brain to sort through the entire wealth of information it has accumulated over its lifetime. This pitfall could explain why ANNs lose long-term knowledge when they absorb new data too quickly.

Traditionally, the solution used in deep machine learning to retrain the network on the entire set of data from the past, whether closely related to the new information, was a very time-consuming process. The UCI scientists decided to investigate the matter further and made a remarkable discovery.

“We found that when ANNs inserted a much smaller subset of old information, including mostly items similar to the new knowledge they were acquiring, they learned it without forgetting what they already knew,” said graduate student Rajat Saxena, the first author of the article. † Saxena led the project with help from Justin Shobe, an assistant project scientist. Both members of the lab of Bruce McNaughton, Distinguished Professor of Neurobiology and Behavior.

“It allowed ANNs to absorb new information very efficiently, without having to review everything they had previously collected,” Saxena said. “These findings suggest a brain mechanism why experts in something can learn new things in that area much faster than non-experts. If the brain already has a cognitive framework regarding the new information, the new material can be absorbed more quickly because there are only changes are needed in the part of the brain network that encodes the expert knowledge.”

According to McNaughton, the discovery offers opportunities to address cognitive problems. “Understanding the mechanisms behind learning is essential to progress,” he said. “It gives us insight into what happens when the brain doesn’t work the way it should. We could develop training strategies for people with memory problems due to aging or people with brain damage. It could also lead to the ability to manipulate brain circuits so that humans can overcome these deficits.”

The findings also provide opportunities to make algorithms in machines such as medical diagnostic equipment, autonomous cars and many others more accurate and efficient.

Funding for the research was provided by a Defense Advanced Research Projects Agency Grant to support 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 in the top 10 public universities in the country by US news and world report† The campus has produced five Nobel laureates and is known for its academic achievements, top-notch research, innovation and anteater mascot. Under the leadership of Chancellor Howard Gillman, UCI has more than 36,000 students and offers 224 degree programs. Located in one of the world’s safest and most economically vibrant communities, it is Orange County’s second largest employer, contributing $7 billion annually to the local economy and $8 billion statewide. For more information about UCI, visit www.uci.edu

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