UCI team uncovers key brain mechanism for timely organization of memories

For the first time in science, researchers at the University of California, Irvine have discovered the basic mechanism by which the hippocampus of the brain organizes memories into sequences and how this mechanism is used to plan future behaviors

Combining electrophysiological recording techniques in rodents with statistical machine-learning analysis of large amounts of data, UCI researchers found evidence of advances in hippocampal networks encoding and preserving experience to aid decision-making

"Our brains are very good at recording the timing of specific experiences or events

The project took more than three years to complete and involved the experimental and data analysis phases

"I think the analogy is computing," Fortin said

Measurements of neuronal activity and inactivity are obtained over minutes at millisecond intervals, presenting a dynamic picture of brain function

"When you're thinking about something, it moves quickly," he said

Fortin has long known that readings of activity in the hippocampus yield a wealth of raw data

“The neuroscience problems we had in the lab at the time were simply too advanced for our statistical knowledge

"These emerging neuroscience studies rely on data science methods because their data are complex," said senior co-author Babak Shahbaba, a Chancellor's Fellow and professor of statistics at UCI

He noted that when neurons encode information such as memories, scientists can learn about this process by examining the patterns of peak activity of all recorded neurons, collectively referred to as a ensemble

"We found that we could view these neural patterns as images, which opened up our ability to apply deep machine learning methods," Shahbaba said

In this way, the researchers were able to decode the firing of neurons to obtain information

"We know what the signature of odor B looks like, just as we know the signature of odors A, C and D," Fortin said

The tools and methods developed in this project can be applied to many problems, and Fortin may extend his research to other areas of the brain, Shahbaba said

This study is an example of the convergence of research power at institutions such as UCI

He added, "Through this collaboration, we are training the next generation of scientists with the skills needed to conduct interdisciplinary research
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Fortin and Shahbaba worked on the project with Pierre Baldi, Distinguished Professor of Computer Science at UCI; Lingge Li, PhD in Statistics at UCI in 2020; Forest Agostinelli, PhD in Computer Science at UCI in 2019 and now an assistant professor at the University of South Carolina ; UCI neurobiology and behavior doctoral students Mansi Saraf and Keiland Cooper; UCLA statistics doctoral student Derenik Haghverdian; and UC Irvine postdoctoral program scientist Gabriel Elias
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Funding was provided by the National Institutes of Health, the National Science Foundation, and the Whitehall Foundation
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About UC Irvine: Founded in 1965, UC Irvine is the youngest member of the prestigious Association of American Universities and is rated by US News & World Report The top ten public universities in the United States
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The campus has produced 5 Nobel Prize winners and is known for its academic achievement, research excellence, innovation and the Anteater mascot
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Under the leadership of Chancellor Howard Gilman, UCI has more than 36,000 students and offers 224 degree programs
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Located in one of the safest and most economically active communities in the world, it is Orange County's largest employer, contributing $7 billion annually to the local economy and $8 billion to the state
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For more information about UCI, visit
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article title

Hippocampal ensembles represent sequential relationships among an extended sequence of nonspatial events