Stopping the brain's memory circuits from overheatingMay 03, 2017
The highly interconnected zones of the brain's hippocampus mediate spatial and episodic memory, but to keep memories organized they need the right balance of exciting and calming input. A part of the hippocampus called CA2 has been found to be responsible for this regulation, preventing the local brain circuits from becoming hyperactive. In the absence of CA2 activity, mice experience epilepsy-like activity, a sign that this area is essential for regulating the balance of excitation and inhibition in the brain. A silenced CA2 region has broader implications for information processing in hippocampal circuits, according to a new study from the RIKEN Brain Science Institute (BSI) in Japan and the Université Paris Descartes.
RIKEN BSI team leader Thomas McHugh and colleagues studied mice that had either temporary or permanent CA2 impairment. As they reported on May 3rd in the journal Neuron, CA2 is responsible for maintaining inhibition throughout its connected network.
Investigating the connections from CA2 to hippocampal neighbors CA1 and CA3, the researchers found that optogenetic stimulation there translated into a suppression of signaling in the network, especially in CA3. They further probed this inhibition by shutting down signaling from CA2 with a nerve toxin, which resulted in a 'hyperexcitable' network state within CA3.
These observations, which were made in brain slices, were replicated and expanded in behaving mice. During exploration of open areas and tracks, mice with silenced CA2 activity displayed increases in local field potentials, the summed electric current from a larger group of neurons in the hippocampus. McHugh's research group has previously reported how this kind of brain wave activity organizes spatial coding in the hippocampus. This time they found that large increases in the power of the slow-wave activity of 4-12 Hz, dubbed the theta band, along with bursts of high-frequency oscillations, were spatially triggered. "These episodes of hyperexcitability lasted one or two seconds and were tied to specific locations visited by the mice," said McHugh.
In resting or immobile mice, however, the researchers observed something quite different: short, frequent, large-amplitude voltage spikes reminiscent of epileptic brain activity. "Normal ripple waves across the hippocampus appear to be substituted by these epileptiform-like discharges that originate in CA3, which becomes highly excitable without CA2 gating its activity," observed McHugh. These mice were also more susceptible to seizures induced by an injected neurotoxin compared to control mice.
CA2 thus appears to be a vital part of controlling the spread of excitatory neural activity in the hippocampus, potentially preventing it from entering a state of pathological spiking. Further study is needed to determine how this affects navigation and memory in mice, however. "The hippocampus encodes place, and we saw a subtle shift in the spatial organization of pyramidal cells spiking in the face of CA2 inhibition. We still need to explore how timing and strength of inputs in this degraded network manifests in these interesting changes," said McHugh.
Boehringer R, Polygalov D, Huang AJY, Middleton SJ, Robert V, Wintzer ME, Piskorowski RA, Chevaleyre V, McHugh TJ (2017) Chronic loss of CA2 transmission leads to hippocampal hyperexcitability. Neuron, doi: 10.106/j.neuron.2017.04.14.
Related Memory Articles:
A quick glance at any social media platform will tell you that people love taking photos of their experiences -- whether they're lying on the beach, touring a museum, or just waiting in line at the grocery store.
Research from Katherine Duncan at the University of Toronto suggests we may have to rethink how we improve memory.
The ability to remember sounds, and manipulate them in our minds, is incredibly important to our daily lives -- without it we would not be able to understand a sentence, or do simple arithmetic.
In the battle of the sexes, women have long claimed that they can remember things better and longer than men can.
A collaboration between Universitat Autònoma de Barcelona and Harvard University pioneers the increase of memory using optogenetics in mice in Spain.
Peppermint tea can improve long-term and working memory and in healthy adults.
MIT study finds bursts of neural activity as the brain holds information in mind, overturns a long-held model.
For over forty years, neuro-scientists have been interested in the biological mechanisms underlying the storage of the information that our brain records every day.
Why is it that some people have richly detailed recollection of past experiences (episodic memory), while others tend to remember just the facts without details (semantic memory)?
Neuroscientists at Rosalind Franklin University of Medicine and Science have discovered a novel mechanism for memory formation.
Related Memory Reading:
Unlimited Memory: How to Use Advanced Learning Strategies to Learn Faster, Remember More and be More Productive
by Kevin Horsley (Author)
Kevin Horsley Broke a World Memory Record in 2013...
And You're About to Learn How to Use His Memory Strategies to Learn Faster, Be More Productive and Achieve More Success
Most people never tap into 10% of their potential for memory. In this book, you're about to learn:
How the World's Top Memory Experts Concentrate and Remember Any Information at Will, and How You Can Too
Do you ever feel like you're too busy, too stressed or just too distracted to concentrate and get work done? In Unlimited Memory, you'll learn how the world's best memory masters... View Details
Memory Rescue: Supercharge Your Brain, Reverse Memory Loss, and Remember What Matters Most
by Dr. Daniel G. Amen (Author)
A proven program from #1 New York Times bestselling author and brain researcher Dr. Daniel Amen to help you change your brain and improve your memory today!
Brain imaging research demonstrates that memory loss actually starts in the brain decades before you have any symptoms. Learn the actions you can take to help not just prevent memory loss later in life . . . but to begin restoring the memory you may have already lost.
Expert physician Dr. Amen reveals how a multipronged strategy―including dietary changes, physical and mental exercises, and spiritual... View Details
by Alan Baddeley (Author), Michael W. Eysenck (Author), Michael C. Anderson (Author)
This best-selling textbook presents a comprehensive and accessible overview of the study of memory. Written by three of the world’s leading researchers in the field, it contains everything the student needs to know about the scientific approach to memory and its applications.
Each chapter of the book is written by one of the three authors, an approach which takes full advantage of their individual expertise and style, creating a more personal and accessible text. This enhances students’ enjoyment of the book, allowing them to share the authors’ own fascination with human... View Details
In Pursuit of Memory: The Fight Against Alzheimer's
by Joseph Jebelli (Author)
For readers of Atul Gawande, Siddhartha Mukherjee, and Henry Marsh, a riveting, gorgeously written biography of one of history's most fascinating and confounding diseases--Alzheimer's--from its discovery more than 100 years ago to today's race towards a cure.
SHORTLISTED FOR THE ROYAL SOCIETY SCIENCE BOOK PRIZE 2017
Named "Science Book of the Month" by Bookseller
Alzheimer's is the great global epidemic of our time, affecting millions worldwide -- there are more than 5 million people diagnosed in the US alone. And as our population ages, scientists... View Details
The Memory Book: The Classic Guide to Improving Your Memory at Work, at School, and at Play
by Harry Lorayne (Author), Jerry Lucas (Author)
Unleash the hidden power of your mind through Harry Lorayne and Jerry Lucas's simple, fail-safe memory system, and you can become more effective, more imaginative, and more powerful, at work, at school, in sports and play. Discover how easy it is to: file phone numbers, data, figures, and appointments right in your head; learn foreign words and phrases with ease; read with speed--and greater understanding; shine in the classroom--and shorten study hours; dominate social situations, and more.
From the Paperback edition. View Details
In Search of Memory: The Emergence of a New Science of Mind
by Eric R. Kandel (Author)
“A stunning book.”―Oliver SacksMemory binds our mental life together. We are who we are in large part because of what we learn and remember. But how does the brain create memories? Nobel Prize winner Eric R. Kandel intertwines the intellectual history of the powerful new science of the mind―a combination of cognitive psychology, neuroscience, and molecular biology―with his own personal quest to understand memory. A deft mixture of memoir and history, modern biology and behavior, In Search of Memory brings readers from Kandel's childhood in... View Details
The Memory Illusion: Remembering, Forgetting, and the Science of False Memory
by Dr. Julia Shaw (Author)
Memories make us who we are—yet the truth is they are far from being the accurate record we like to think they are. We can all admit to occasional memory lapses, but what if we have the potential for more profound errors of memory, even verging on outright fabrication and self-deception? Forensic psychologist and memory expert Dr. Julia Shaw uses the latest research to show the astonishing variety of ways in which our brains can be led astray. She shows why we can misappropriate other people's memories, believing them to be our own. She explains how police officers can imprison an innocent... View Details
Moonwalking with Einstein: The Art and Science of Remembering Everything
by Joshua Foer (Author)
The blockbuster phenomenon that charts an amazing journey of the mind while revolutionizing our concept of memory
An instant bestseller that is poised to become a classic, Moonwalking with Einstein recounts Joshua Foer's yearlong quest to improve his memory under the tutelage of top "mental athletes." He draws on cutting-edge research, a surprising cultural history of remembering, and venerable tricks of the mentalist's trade to transform our understanding of human memory. From the United States Memory Championship to deep within the author's own mind, this is an... View Details
Memories: From Moscow to the Black Sea (New York Review Books Classics)
by Teffi (Author), Robert Chandler (Translator), Anne Marie Jackson (Translator), Elizabeth Chandler (Translator), Irina Steinberg (Translator), Edythe Haber (Translator)
Considered Teffi’s single greatest work, Memories: From Moscow to the Black Sea is a deeply personal account of the author’s last months in Russia and Ukraine, suffused with her acute awareness of the political currents churning around her, many of which have now resurfaced.
In 1918, in the immediate aftermath of the Russian Revolution, Teffi, whose stories and journalism had made her a celebrity in Moscow, was invited to read from her work in Ukraine. She accepted the invitation eagerly, though she had every intention of returning home. As it happened, her trip ended four... View Details
Memories, Dreams, Reflections
by C. G. Jung (Author), Aniela Jaffe (Editor), Clara Winston (Editor), Richard Winston (Editor)
An eye-opening biography of one of the most influential psychiatrists of the modern age, drawing from his lectures, conversations, and own writings.
In the spring of 1957, when he was eighty-one years old, Carl Gustav Jung undertook the telling of his life story. Memories, Dreams, Reflections is that book, composed of conversations with his colleague and friend Aniela Jaffé, as well as chapters written in his own hand, and other materials. Jung continued to work on the final stages of the manuscript until shortly before his death on June 6, 1961, making this a uniquely... View Details