New study suggests an unconventional way for memories to form

September 8, 2017 by Bob Yirka, Medical Xpress report
Credit: Wikimedia Commons

(Medical Xpress)—A team of researchers working at Howard Hughes Medical Institute has found possible evidence of a way for memories to form that differs from conventional theory. In their paper published in the journal Science, the team describes their theory, the biophysical model they built and what their findings suggest about the way some memories may form. Julija Krupic with University College London offers a Perspective piece on the study in the same issue and gives some background on memory research in general.

After many years of research, brain scientists have come to some degree of consensus about how the brain forms memories—as Krupic notes, it happens as a result of the creation of neural networks that are strengthened when neurons in the network cause or contribute to activity occurring in a connected neuron—the idea has become known as the Hebbian learning rule. Under the rule, memories are formed due to activities that occur very closely in time, allowing the neurons time to build stronger bonds for those events that are more memorable.

The theory also embraces the idea of plasticity—the network must changeable in order for a memory to strengthen. The theory further suggests that memories are added to or recalled by neurons firing in quick succession in short bursts of activity, a process called long-term potentiation (LTP). In this new effort, the researchers suggest there might be a different type of memory processing that happens over longer periods of time. Such memories, they suggest, could help with remembering events as a sequence, rather than just as snapshots. They call this new memory mechanism behavioral time scale synaptic plasticity (BTSP).

The new suggests that there need not be a relationship between interconnected during sequential formation to maintain associations that can be long-lasting—instead, place fields are involved. To test the plausibility of their ideas, the researchers built a biophysical model based on what might happen with place fields during times when a mouse is moving faster versus slower—it showed the idea to be plausible. A BTSP mechanism, Krupic notes, could lead to over-representation of places that are important to a mouse—such as the steps required to get to a good food source, allowing it to find such a source when snapshot types of memories alone will not suffice.

Explore further: Laser used to reawaken lost memories in mice with Alzheimer's disease

More information: Katie C. Bittner et al. Behavioral time scale synaptic plasticity underlies CA1 place fields, Science (2017). DOI: 10.1126/science.aan3846

Abstract
Learning is primarily mediated by activity-dependent modifications of synaptic strength within neuronal circuits. We discovered that place fields in hippocampal area CA1 are produced by a synaptic potentiation notably different from Hebbian plasticity. Place fields could be produced in vivo in a single trial by potentiation of input that arrived seconds before and after complex spiking. The potentiated synaptic input was not initially coincident with action potentials or depolarization. This rule, named behavioral time scale synaptic plasticity, abruptly modifies inputs that were neither causal nor close in time to postsynaptic activation. In slices, five pairings of subthreshold presynaptic activity and calcium (Ca2+) plateau potentials produced a large potentiation with an asymmetric seconds-long time course. This plasticity efficiently stores entire behavioral sequences within synaptic weights to produce predictive place cell activity.

Related Stories

Laser used to reawaken lost memories in mice with Alzheimer's disease

July 26, 2017
(Medical Xpress)—A team of researchers at Columbia University has found that applying a laser to the part of a mouse brain used for memory storage caused the mice to recall memories lost due to a mouse version of Alzheimer's ...

Modeling memory in the brain

May 18, 2015
Scientists at EPFL have uncovered mathematical equations behind the way the brain forms – and even loses – memories.

Neuroscientists call for more comprehensive view of how brain forms memories

July 5, 2017
Neuroscientists from the University of Chicago argue that research on how memories form in the brain should consider activity of groups of brain cells working together, not just the connections between them.

Research team may have observed building blocks of memories in the brain

September 20, 2016
(Medical Xpress)—A team of researchers working at Aix-Marseille University in France has observed what they believe are the building blocks of memories in a mouse brain. In their paper published in the journal Science, ...

Study sheds new light on the formation of emotional fear memories

December 8, 2014
Everyday events are easy to forget, but unpleasant ones can remain engraved in the brain. A new study published in the Proceedings of the National Academy of Sciences identifies a neural mechanism through which unpleasant ...

Watching a memory form: Sea slug study reveals novel memory mechanism

November 5, 2015
Neuroscientists at Rosalind Franklin University of Medicine and Science have discovered that some neurons are joiners—seemingly eager to link-up with networks in which learning is taking place.

Recommended for you

New neuron-like cells allow investigation into synthesis of vital cellular components

January 22, 2018
Neuron-like cells created from a readily available cell line have allowed researchers to investigate how the human brain makes a metabolic building block essential for the survival of all living organisms. A team led by researchers ...

Finding unravels nature of cognitive inflexibility in fragile X syndrome

January 22, 2018
Mice with the genetic defect that causes fragile X syndrome (FXS) learn and remember normally, but show an inability to learn new information that contradicts what they initially learned, shows a new study by a team of neuroscientists. ...

Epilepsy linked to brain volume and thickness differences

January 22, 2018
Epilepsy is associated with thickness and volume differences in the grey matter of several brain regions, according to new research led by UCL and the Keck School of Medicine of USC.

Research reveals atomic-level changes in ALS-linked protein

January 18, 2018
For the first time, researchers have described atom-by-atom changes in a family of proteins linked to amyotrophic lateral sclerosis (ALS), a group of brain disorders known as frontotemporal dementia and degenerative diseases ...

Fragile X finding shows normal neurons that interact poorly

January 18, 2018
Neurons in mice afflicted with the genetic defect that causes Fragile X syndrome (FXS) appear similar to those in healthy mice, but these neurons fail to interact normally, resulting in the long-known cognitive impairments, ...

How your brain remembers what you had for dinner last night

January 17, 2018
Confirming earlier computational models, researchers at University of California San Diego and UC San Diego School of Medicine, with colleagues in Arizona and Louisiana, report that episodic memories are encoded in the hippocampus ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

gghartmail
not rated yet Sep 08, 2017
Forming memories? This sounds like muscle memory. True memories are the millions of fine analog particulars of data: is that address 1.1.21 or 1.1.12. Music code, colors, computer code, mathematics, language, grammar, the millions of fine brush strokes or pencil marks in artwork, the detailed schematics of architectural drawing. All of these finely detailed shapes, sounds, symbols, colors, smells, tastes, etc are what memory is. How does a neuron distinguish these differences?
Anyone have a clue? Thanks.
Sassen
not rated yet Sep 09, 2017
80% of our brain is involved with movement and muscles.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.