Nav: Home

Scientists reveal how the brain maintains useful memories

February 14, 2017

Researchers from the University of Toronto, Canada, have discovered a reason why we often struggle to remember the smaller details of past experiences.

Writing in the journal eLife, the team found that there are specific groups of neurons in the medial prefrontal cortex (mPFC) of a rat's brain - the region most associated with long-term memory. These neurons develop codes to help store relevant, general information from multiple experiences while, over time, losing the more irrelevant, minor details unique to each experience.

The findings provide new insight into how the brain collects and stores useful knowledge about the world that can be adapted and applied to new experiences.

"Memories of recent experiences are rich in incidental detail but, with time, the brain is thought to extract important information that is common across various past experiences," says Kaori Takehara-Nishiuchi, senior author and Associate Professor of Psychology at the University of Toronto. "We predicted that groups of neurons in the mPFC build representations of this information over the period when long-term memory consolidation is known to take place, and that this information has a larger representation in the brain than the smaller details."

To test their prediction, the team studied how two different memories with overlapping associative features are coded by neuron groups in the mPFC of rat brains, and how these codes change over time.

Rats were given two experiences with an interval between each: one involving a light and tone stimulus, and the other involving a physical stimulus. This gave them two memories that shared a common stimulus relationship. The scientists then tracked the neuron activity in the animals' brains from the first day of learning to four weeks following their experiences.

"This experiment revealed that groups of neurons in the mPFC initially encode both the unique and shared features of the stimuli in a similar way," says first author Mark Morrissey, formerly a graduate researcher at the University of Toronto. "However, over the course of a month, the coding becomes more sensitive to the shared features and less sensitive to the unique features, which become lost."

Further experiments also revealed that the brain can adapt the general knowledge gained from multiple experiences immediately to a new situation.

"This goes some way to answering the long-standing question of whether the formation of generalised memory is simply a result of the brain's network 'forgetting' incidental features," Morrissey explains. "On the contrary, we show that groups of neurons develop coding to store shared information from different experiences while, seemingly independently, losing selectivity for irrelevant details."

Morrissey adds that the unique coding property of the mPFC identified in the study may support its role in the formation, maintenance, and updating of associative knowledge structures that help support flexible and adaptive behaviour in rats and other animals.
-end-
Reference

The paper 'Generalizable knowledge outweighs incidental details in prefrontal ensemble code over time' can be freely accessed online at http://dx.doi.org/10.7554/eLife.22177. Contents, including text, figures, and data, are free to reuse under a CC BY 4.0 license.

Media contact

Emily Packer, eLife
e.packer@elifesciences.org
01223 855373

About eLife

eLife is a unique collaboration between the funders and practitioners of research to improve the way important research is selected, presented, and shared. eLife publishes outstanding works across the life sciences and biomedicine -- from basic biological research to applied, translational, and clinical studies. All papers are selected by active scientists in the research community. Decisions and responses are agreed by the reviewers and consolidated by the Reviewing Editor into a single, clear set of instructions for authors, removing the need for laborious cycles of revision and allowing authors to publish their findings quickly. eLife is supported by the Howard Hughes Medical Institute, the Max Planck Society, and the Wellcome Trust. Learn more at elifesciences.org.

eLife

Related Neurons Articles:

New tool to identify and control neurons
One of the big challenges in the Neuroscience field is to understand how connections and communications trigger our behavior.
Neurons that regenerate, neurons that die
In a new study published in Neuron, investigators report on a transcription factor that they have found that can help certain neurons regenerate, while simultaneously killing others.
How neurons use crowdsourcing to make decisions
When many individual neurons collect data, how do they reach a unanimous decision?
Neurons can learn temporal patterns
Individual neurons can learn not only single responses to a particular signal, but also a series of reactions at precisely timed intervals.
A turbo engine for tracing neurons
Putting a turbo engine into an old car gives it an entirely new life -- suddenly it can go further, faster.
Brain neurons help keep track of time
Turning the theory of how the human brain perceives time on its head, a novel analysis in mice reveals that dopamine neuron activity plays a key role in judgment of time, slowing down the internal clock.
During infancy, neurons are still finding their places
Researchers have identified a large population of previously unrecognized young neurons that migrate in the human brain during the first few months of life, contributing to the expansion of the frontal lobe, a region important for social behavior and executive function.
How many types of neurons are there in the brain?
For decades, scientists have struggled to develop a comprehensive census of cell types in the brain.
Molecular body guards for neurons
In the brain, patterns of neural activity are perfectly balanced.
Engineering researchers use laser to 'weld' neurons
University of Alberta researchers have developed a method of connecting neurons, using ultrashort laser pulses -- a breakthrough technique that opens the door to new medical research and treatment opportunities.

Related Neurons Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".