UT Southwestern researchers discover brain's memory 'buffer' in single cells

January 26, 2009

Individual nerve cells in the front part of the brain can hold traces of memories on their own for as long as a minute and possibly longer, researchers at UT Southwestern Medical Center have found.

The study, available online and appearing in the February issue of Nature Neuroscience, is the first to identify the specific signal that establishes nonpermanent cellular memory and reveals how the brain holds temporary information. It has implications for addiction, attention disorders and stress-related memory loss, said Dr. Don Cooper, assistant professor of psychiatry at UT Southwestern and senior author of the study conducted in mice.

Researchers have known that permanent memories are stored when the excitatory amino acid glutamate activates ion channels on nerve cells in the brain to reorganize and strengthen the cells' connections with one another. But this process takes minutes to hours to turn on and off and is too slow to buffer, or temporarily hold, rapidly incoming information.

The researchers found that rapid-fire inputs less than a second long initiate a cellular memory process in single cells lasting as long as minute, a process called metabotropic glutamate transmission. This transmission in the most highly evolved brain region holds moment-to-moment information.

These cellular findings have implications for how the human brain stores rapidly changing information, like the temporary memory a card shark uses when counting cards in a game of Black Jack and, as casinos have figured out, it is the memory that is most sensitive to the disruptive effects of alcohol and noisy distractions, Dr. Cooper said.

"It's more like RAM [random access memory] on a computer than memory stored on a disk," Dr. Cooper said. "The memory on the disk is more permanent and you can go back and access the same information repeatedly. RAM memory is rewritable temporary storage that allows multitasking."

The researchers identified in mice a specific metabotropic glutamate receptor called mGluR5 that, when turned on, starts a signaling cascade using calcium to hold a memory trace. This fast, short-term memory process happens inside individual cells; with long-term memory, additional proteins cause slow reorganization between cells in a network to establish a permanent memory.

Researchers examined brain cells from mice using nanoscale electrodes to measure the memory formation process.

To further understand how this short-term memory process relates to addiction, researchers applied the neurochemical dopamine to the memory buffer nerve cells. Dopamine is normally needed at an optimal level for an individual to focus attention and engage in fast decision-making memory, but drugs of abuse overload the brain with a surge of dopamine. In the study, researchers found that an experimental drug that activates a specific type of dopamine receptor "focused" the nerve cells, making the memory trace less susceptible to distraction.

When researchers employed an animal model of drug addiction using cocaine, they also found that repeated exposure to addictive levels of cocaine reduced memory trace activation in the memory buffer cells. When researchers then activated dopamine signaling in the "addicted" animals, essentially adding more dopamine to their systems, no focusing effect was observed.

"This makes sense because we know from human and animal models of addiction, when a decision using working memory has to be made, brain imaging shows a deficit in the same area of the brain we looked at," Dr. Cooper said. "It all fits together."

Researchers next plan to identify the ion channel responsible for holding and regenerating a memory trace. Their goal is to develop new pharmacological and genetic tools that will allow them to manipulate and possibly expand decision-making memory capacity.

"If we can identify and manipulate the molecular components of memory, we can develop drugs that boost the ability to maintain this memory trace to hopefully allow a person to complete tasks without being distracted," Dr. Cooper said. "For the person addicted to drugs, we could strengthen this part of the brain involved with decision-making, allowing them to ignore impulses and weigh negative consequences of their behavior before they abuse drugs."

Other researchers from UT Southwestern involved in the study in Dr. Cooper's laboratory were Dr. Fang-Min Lu, assistant instructor of psychiatry; Melissa Fowler, a graduate student in psychiatry; Christopher Phillips, a medical student; and Emin Ozkan, student research assistant in physiology. Lead author Kyriaki Sidiropoulou from Rosalind Franklin University of Medicine and Science's Chicago Medical School and researchers from Ohio State University also participated in the study.

The study was funded by the National Institute on Drug Abuse; National Alliance for Research on Schizophrenia and Depression; the Alexander S. Onassis Public Benefit Foundation; and the Department of Veterans Affairs.

UT Southwestern Medical Center

---

---

	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.
	Assimilative Memory, Or, How To Attend And Never Forget by Alphonse Loisette (Author) This is a reproduction of a book published before 1923. This book may have occasional imperfections such as missing or blurred pages, poor pictures, errant marks, etc. that were either part of the original artifact, or were introduced by the scanning process. We believe this work is culturally important, and despite the imperfections, have elected to bring it back into print as part of our continuing commitment to the preservation of printed works worldwide. We appreciate your understanding of the imperfections in the preservation process, and hope you enjoy this valuable book. ...
	Your Memory : How It Works and How to Improve It by Kenneth L. Higbee (Author) Do you want to stop forgetting appointments, birthdays, and other important dates? Work more efficiently at your job? Study less and get better grades? Remember the names and faces of people you meet? The good news is that it's all possible. Your Memory will help to expand your memory abilities beyond what you thought possible. Dr. Higbee reveals how simple techniques, like the Link, Loci, Peg, and Phonetic systems, can be incorporated into your everyday life and how you can also use these techniques to learn foreign languages faster than you thought possible, remember details you would have otherwise forgotten, and overcome general absentmindedness. Higbee also includes sections on aging and memory and the latest information on the use of mnemonics.
	Memory by Alan Baddeley (Author), Michael W. Eysenck (Author), Michael C. Anderson (Author) People seem to be intrigued by memory, and by its sometimes spectacular failure in (for example) people with amnesia. However, students of memory sometimes fail to retain this fascination. The reason is clear: in order to study memory we must carry out carefully-designed experiments, which can seem boring even when they are exciting science. Fortunately, we now know enough about memory to relate laboratory studies to the world beyond. In other words, our scientific knowledge of memory and how it works can help us to explain those aspects of memory that most people find of greatest interest. This book presents a thorough, accessible and appealing overview of the field, written with students in mind, by some of the world's leading researchers. It starts with a brief overview and...
	The Manual- A guide to the Ultimate Study Method (USM); covering Speed Reading, Super Memory, Laser Concentration, Rapid Mental Arithmetic and the Ultimate Study Method (USM) “The Manual” is the ultimate guide to Speed Reading, Super Memory, Laser Concentration, Rapid mental arithmetic and Optimal learning strategies. Some of the specific implementations and examples presented have not been documented in print before. The techniques discussed are the culmination of decades of practical experience combined with the latest scientific research, as well as time-tested methods. The system described herewith will allow the practitioner to: • Read faster with higher comprehension • Remember any type of information instantly • Store information in long term memory • Enhance concentration and focus • Access deeper levels of mind • Induce relaxation • Rapidly perform complex mental arithmetic • Master...
	Memory Improvement: How To Improve Your Memory In Just 30 Days by Laurenzana Press * Have you ever walked into a room and couldn't remember what you went there for? * Have you ever grasped the hand of a potential client and then when the handshake broke, the name seemed to disappear from your memory? * Or have you ever left a prospect or an important meeting and as you drove away remembered a key point that you should have shared with them? The problem is NOT with your memory. The problem is with the "Filing System" your brain currently uses to store and retrieve memory items. Change the filing system and you'll double and even triple your memory comprehension. Two-time USA Memory Champion Ron White will teach you the same 2,000-year-old memory method that he has already taught thousands to: * Give presentations...
	In Search of Memory: The Emergence of a New Science of Mind by Eric R. Kandel (Author) “A stunning book.”—Oliver SacksCharting the intellectual history of the emerging biology of mind, Eric R. Kandel illuminates how behavioral psychology, cognitive psychology, neuroscience, and molecular biology have converged into a powerful new science of mind. This science now provides nuanced insights into normal mental functioning and disease, and simultaneously opens pathways to more effective healing. Driven by vibrant curiosity, Kandel’s personal quest to understand memory is threaded throughout this absorbing history. Beginning with his childhood in Nazi-occupied Vienna, In Search of Memory chronicles Kandel’s outstanding career from his initial fascination with history and psychoanalysis to his groundbreaking work on the biological process of memory, which...
	Memory (Vorkosigan Saga) Forced to abandon his undercover role as leader of the Dendarii Mercenaries, Miles Vorkosigan persuades Emperor Gregor to appoint him Imperial Auditor so he can penetrate Barrayar’s intelligence and security operations (ImpSec). Simon Illyan, head of ImpSec and Miles’ former boss, is failing physically and mentally, and Miles sets out to find out why -- and who, if anyone, is behind Illyan’s rapid decline. Library Journal calls Miles “one of the genre’s most enterprising and engaging heroes”. A Hugo and Nebula Award finalist. "Not only does Ms. Bujold thoroughly entertain us with Miles' Machiavellian adventures, she also brings just the right touch of vulnerability to his gallant spirit." - Rave Reviews “Bujold continues to prove what marvels...
	Mind Maps: Quicker Notes, Better Memory, and Improved Learning by SelfMadeEasy.com Mind Mapping is a note taking system which allows you to take better, faster, and more efficient notes. In conventional note-taking, you write down information line by line. With Mind Maps, you organize the information more in the form of a diagram, starting with a central key idea drawn in the center of the paper. In addition to enhancing your note taking skills, Mind Maps help you improve your studying, writing, presenting, brainstorming, and creative skills. It is one of the best note taking skills anyone can learn.
	Ageless Memory: The Memory Expert's Prescription for a Razor-Sharp Mind by Harry Lorayne (Author) The world's foremost memory expert—and mega-bestselling author—proves that memory CAN get better with age! Diet and exercise are great, but what good is a healthy body if you don't have the mental capabilities to go with it? Harry Lorayne, who is now 83 years old, has been honing and teaching his foolproof system for sharpening the mind, improving concentration, and attaining a truly "superpower" memory for more than 40 years. Ageless Memory is the culmination of this memory expert's life's work. Specifically geared to our needs as we age, his unique memory system can be put into practice immediately—for a better memory the very same day you open the book and start to read! Completely practical and easy to use, readers learn to: Recall names and faces, even years...