Nav: Home

New system for forming memories

January 12, 2017

Until now, the hippocampus was considered the most important brain region for forming and recalling memory, with other regions only contributing as subordinates. But a study published today in Science finds that a brain region called entorhinal cortex plays a new and independent role in memory. A team of researchers led by Jozsef Csicsvari, Professor at the Institute of Science and Technology Austria (IST Austria), showed that, in rats, the entorhinal cortex replays memories of movement independent of input from the hippocampus.

"Until now, the entorhinal cortex has been considered subservient to the hippocampus in both memory formation and recall. But we show that the medial entorhinal cortex can replay the firing pattern associated with moving in a maze independent of the hippocampus. The entorhinal cortex could be a new system for memory formation that works in parallel to the hippocampus", Jozsef Csicsvari explains.

When a spatial memory is formed, cells in the medial entorhinal cortex (MEC), especially grid cells, act like a navigational system. They provide the hippocampus with information on where an animal is and give cues as to how far and in what direction the animal has moved. Rats encode location and movement by forming networks of neurons in the hippocampus that fire together. When a memory is recalled for memory stabilization, the MEC has been considered as secondary to the hippocampus. In the hippocampus, such recall occurs during the so-called "sharp wave/ripples", when neuronal networks fire in a highly synchronized way. According to the view prevailing until now, the hippocampus is the initiator of this replay and coordinates memory consolidation, while the MEC is just a relay post that spreads the message to other brain areas.

To ask whether replay also occurs in the MEC, the researchers studied memory recall in rats moving in a maze. They showed that neurons in the superficial layers of the medial entorhinal cortex (sMEC), a part of MEC that sends input to the hippocampus and contain the grid cells, fire during the memory task and encode routes as bursts of firing. Surprisingly, the authors find that replay firing in the sMEC is not accompanied by replay firing in the hippocampus. During both sleep and waking periods, the sMEC triggers its own replay and initiates recall and consolidation independent of the hippocampus. Joseph O'Neill, first author and postdoc in the group of Jozsef Csicsvari, explains how these results change the way we see memory formation: "The hippocampus alone does not dominate how memories are formed and recalled. Instead, the entorhinal cortex and the hippocampus are probably two systems for memory formation and recall. Despite being interrelated, the two regions may work in parallel. They may recruit different pathways and play different roles in memory."
-end-


Institute of Science and Technology Austria

Related Memory Articles:

How long does memory last? For shape memory alloys, the longer the better
Scientists captured live action details of the phase transitions of shape memory alloys, giving them a better idea how to improve their properties for applications.
Seeing it both ways: Visual perspective in memory
Think of a memory from your childhood. Are you seeing the memory through your own eyes, or can you see yourself, while viewing that child as if you were an observer?
A NEAT discovery about memory
UAB researchers say over expression of NEAT1, an noncoding RNA, appears to diminish the ability of older brains to form memories.
Molecular memory can be used to increase the memory capacity of hard disks
Researchers at the University of Jyväskylä have taken part in an international British-Finnish-Chinese collaboration where the first molecule capable of remembering the direction of a magnetic above liquid nitrogen temperatures has been prepared and characterized.
Memory transferred between snails
Memories can be transferred between organisms by extracting ribonucleic acid (RNA) from a trained animal and injecting it into an untrained animal, as demonstrated in a study of sea snails published in eNeuro.
An immunological memory in the brain
Inflammatory reactions can change the brain's immune cells in the long term -- meaning that these cells have an 'immunological memory.' This memory may influence the progression of neurological disorders that occur later in life, and is therefore a previously unknown factor that could influence the severity of these diseases.
Anxiety can help your memory
Anxiety can help people to remember things, a study from the University of Waterloo has found.
Pores with a memory
Whether for separation processes, photovoltaics, catalysis, or electronics, porous polymer membranes are needed in many fields.
Memory gene goes viral
Two independent teams of scientists from the University of Utah and the University of Massachusetts Medical School have discovered that a gene crucial for learning, called Arc, can send its genetic material from one neuron to another by employing a strategy commonly used by viruses.
Neurobiology: The chemistry of memory
Learning requires the chemical adaptation of individual synapses. Researchers have now revealed the impact of an RNA-binding protein that is intimately involved in this process on learning and memory formation and learning processes.
More Memory News and Memory Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#542 Climate Doomsday
Have you heard? Climate change. We did it. And it's bad. It's going to be worse. We are already suffering the effects of it in many ways. How should we TALK about the dangers we are facing, though? Should we get people good and scared? Or give them hope? Or both? Host Bethany Brookshire talks with David Wallace-Wells and Sheril Kirschenbaum to find out. This episode is hosted by Bethany Brookshire, science writer from Science News. Related links: Why Climate Disasters Might Not Boost Public Engagement on Climate Change on The New York Times by Andrew Revkin The other kind...
Now Playing: Radiolab

Breaking Bongo
Deep fake videos have the potential to make it impossible to sort fact from fiction. And some have argued that this blackhole of doubt will eventually send truth itself into a death spiral. But a series of recent events in the small African nation of Gabon suggest it's already happening.  Today, we follow a ragtag group of freedom fighters as they troll Gabon's president - Ali Bongo - from afar. Using tweets, videos and the uncertainty they can carry, these insurgents test the limits of using truth to create political change and, confusingly, force us to ask: Can fake news be used for good? This episode was reported and produced by Simon Adler. Support Radiolab today at Radiolab.org/donate.