Research unravels what makes memories so detailed and enduring

September 08, 2020

In years to come, our personal memories of the COVID-19 pandemic are likely to be etched in our minds with precision and clarity, distinct from other memories of 2020. The process which makes this possible has eluded scientists for many decades, but research led by the University of Bristol has made a breakthrough in understanding how memories can be so distinct and long-lasting without getting muddled up.

The study, published in Nature Communications, describes a newly discovered mechanism of learning in the brain shown to stabilise memories and reduce interference between them. Its findings also provide new insight into how humans form expectations and make accurate predictions about what could happen in future.

Memories are created when the connections between the nerve cells which send and receive signals from the brain are made stronger. This process has long been associated with changes to connections that excite neighbouring nerve cells in the hippocampus, a region of the brain crucial for memory formation.

These excitatory connections must be balanced with inhibitory connections, which dampen nerve cell activity, for healthy brain function. The role of changes to inhibitory connection strength had not previously been considered and the researchers found that inhibitory connections between nerve cells, known as neurons, can similarly be strengthened.

Working together with computational neuroscientists at Imperial College London, the researchers showed how this allows the stabilisation of memory representations.

Their findings uncover for the first time how two different types of inhibitory connections (from parvalbumin and somatostatin expressing neurons) can also vary and increase their strength, just like excitatory connections. Moreover, computational modelling demonstrated this inhibitory learning enables the hippocampus to stabilise changes to excitatory connection strength, which prevents interfering information from disrupting memories.

First author Dr Matt Udakis, Research Associate at the School of Physiology, Pharmacology and Neuroscience, said: "We were all really excited when we discovered these two types of inhibitory neurons could alter their connections and partake in learning.

""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 modelling 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 further funding to develop this research and test their predictions from these findings by measuring the stability of memory representations.

Senior author Professor Jack Mellor, Professor in Neuroscience at the Centre for Synaptic Plasticity, said: "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.

"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."

"This is also a great example of how research at the interface of two different disciplines can deliver exciting science with truly new insights. Memory researchers within Bristol Neuroscience form one of the largest communities of memory-focussed research in the UK spanning a broad range of expertise and approaches. It was a great opportunity to work together and start to answer these big questions, which neuroscientists have been grappling with for decades and have wide-reaching implications."
-end-
Paper

'Interneuron-specific plasticity at parvalbumin and somatostatin inhibitory synapses onto CA1 pyramidal neurons shapes hippocampal output' by Matt Udakis, Victor Pedrosa, Sophie Chamberlain, Claudia Clopath and Jack Mellor in Nature Communications

University of Bristol

Related Neurons Articles from Brightsurf:

Paying attention to the neurons behind our alertness
The neurons of layer 6 - the deepest layer of the cortex - were examined by researchers from the Okinawa Institute of Science and Technology Graduate University to uncover how they react to sensory stimulation in different behavioral states.

Trying to listen to the signal from neurons
Toyohashi University of Technology has developed a coaxial cable-inspired needle-electrode.

A mechanical way to stimulate neurons
Magnetic nanodiscs can be activated by an external magnetic field, providing a research tool for studying neural responses.

Extraordinary regeneration of neurons in zebrafish
Biologists from the University of Bayreuth have discovered a uniquely rapid form of regeneration in injured neurons and their function in the central nervous system of zebrafish.

Dopamine neurons mull over your options
Researchers at the University of Tsukuba have found that dopamine neurons in the brain can represent the decision-making process when making economic choices.

Neurons thrive even when malnourished
When animal, insect or human embryos grow in a malnourished environment, their developing nervous systems get first pick of any available nutrients so that new neurons can be made.

The first 3D map of the heart's neurons
An interdisciplinary research team establishes a new technological pipeline to build a 3D map of the neurons in the heart, revealing foundational insight into their role in heart attacks and other cardiac conditions.

Mapping the neurons of the rat heart in 3D
A team of researchers has developed a virtual 3D heart, digitally showcasing the heart's unique network of neurons for the first time.

How to put neurons into cages
Football-shaped microscale cages have been created using special laser technologies.

A molecule that directs neurons
A research team coordinated by the University of Trento studied a mass of brain cells, the habenula, linked to disorders like autism, schizophrenia and depression.

Read More: Neurons News and Neurons Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.