How memories remain stable without interference

How do our memories remain so clear and distinct from each other? The process that makes this possible has been a mystery, but a team of researchers led by the University of Bristol has now discovered a learning mechanism that stabilizes memories and reduces interference between them. 

The breakthrough study will also provide new insight into how humans form expectations and make accurate predictions about what could happen in future.

Memories are created as the connections between neurons are strengthened. These changes excite neighboring nerve cells in the hippocampus, a region of the brain that is critical for memory formation. However, this stimulation must be countered by inhibitory connections that dampen nerve cell activity in order to maintain healthy brain function. 

The inhibitory connections between nerve cells had not been previously investigated for their potential role in memory formation. For the very first time, the researchers demonstrated that these connections can also be strengthened. 

In collaboration with computational neuroscientists at Imperial College London, the experts found that inhibitory connections between nerve cells play an important role in stabilizing memories.

Based on computational modeling, the team also demonstrated that inhibitory learning enables the hippocampus to prevent information from interfering with and disrupting memories.

“We were all really excited when we discovered these two types of inhibitory neurons could alter their connections and partake in learning,” said study first author Dr. Matt Udakis. “It provides an explanation for what we all know to be true; that memories do not disappear as soon as we encounter a new experience. These new findings will help us understand why that is.”

“The computer modeling gave us important new insight into how inhibitory learning enables memories to be stable over time and not be susceptible to interference. That’s really important as it has previously been unclear how separate memories can remain precise and robust.”

The research was funded by the UKRI’s Biotechnology and Biological Sciences Research Council, which has awarded the teams additional funding to develop this research and test their predictions.

“Memories form the basis of our expectations about future events and enable us to make more accurate predictions. What the brain is constantly doing is matching our expectations to reality, finding out where mismatches occur, and using this information to determine what we need to learn,” said study senior author Professor Jack Mellor.

“We believe what we have discovered plays a crucial role in assessing how accurate our predictions are and therefore what is important new information. In the current climate, our ability to manage our expectations and make accurate predictions has never been more important.”

The study is published in the journal Nature Communications.

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By Chrissy Sexton, Earth.com Staff Writer