 |
|
New understanding of basic units of memory
September 20, 2007DURHAM, N.C. - A molecular "recycling plant" permits nerve cells in the brain to carry out two seemingly contradictory functions - changeable enough to record new experiences, yet permanent enough to maintain these memories over time.
The discovery of this molecular recycling plant, detailed in a study appearing early online Sept. 19 in the journal Neuron, provides new insights into how the basic units of learning and memory function. Individual memories are "burned onto" hundreds of receptors that are constantly in motion around nerve synapses - gaps between individual nerve cells crucial for signals to travel throughout the brain.
According to the study's leader, Duke University Medical Center neurobiologist Michael Ehlers, M.D., Ph.D., these receptors are constantly moving around the synapse and often times they disappear or escape. Ehlers discovered that a specific set of molecules catch these elusive receptors, take them to the recycling plant where they are reprocessed and returned to the synapse intact.
"These receptors constantly escape the synapse and are in a perpetual state of recycling," said Ehlers, who is also a Howard Hughes Medical Institute investigator. "This process occurs on a time scale of minutes or hours, so the acquisition of new neurotransmitter receptors and their recycling is an on-going process. Memory loss may result from receptors escaping from the synapse."
All this activity takes place on millions of tiny "nubs," or protrusions in the synapses known as dendritic spines. The recycling plants are located within the body of these dendritic spines.
"We believe that the existence of this recycling ability explains in part how individual dendritic spines retain their unique identity amidst this constant molecular turnover," Ehlers said. "The system is simultaneously dynamic and stable."
While these findings should be able to help neurobiologists as they attempt to understand the molecular foundations of learning and memory, Ehlers believes that this knowledge could also be helpful in explaining what happens in certain neurological disorders, such as Alzheimer's disease, schizophrenia, or learning disorders like autism.
For example, it appears that in animal models of the early phases of Alzheimer's disease, often before any symptoms become apparent, the dendritic spines gradually lose their ability to transport and recycle the receptors.
"If the receptors don't get recycled, you see a gradual loss of synaptic function that is associated with reduced cognitive ability," Ehlers said. "These dendritic spines are where learning and memories reside. These are the basic units of memory."
Duke University Medical Center
"These receptors constantly escape the synapse and are in a perpetual state of recycling," said Ehlers, who is also a Howard Hughes Medical Institute investigator. "This process occurs on a time scale of minutes or hours, so the acquisition of new neurotransmitter receptors and their recycling is an on-going process. Memory loss may result from receptors escaping from the synapse."
All this activity takes place on millions of tiny "nubs," or protrusions in the synapses known as dendritic spines. The recycling plants are located within the body of these dendritic spines.
"We believe that the existence of this recycling ability explains in part how individual dendritic spines retain their unique identity amidst this constant molecular turnover," Ehlers said. "The system is simultaneously dynamic and stable."
While these findings should be able to help neurobiologists as they attempt to understand the molecular foundations of learning and memory, Ehlers believes that this knowledge could also be helpful in explaining what happens in certain neurological disorders, such as Alzheimer's disease, schizophrenia, or learning disorders like autism.
For example, it appears that in animal models of the early phases of Alzheimer's disease, often before any symptoms become apparent, the dendritic spines gradually lose their ability to transport and recycle the receptors.
"If the receptors don't get recycled, you see a gradual loss of synaptic function that is associated with reduced cognitive ability," Ehlers said. "These dendritic spines are where learning and memories reside. These are the basic units of memory."
Duke University Medical Center
Dendritic Spines Current Events and Dendritic Spines News RSSAPP -- Good, bad or both?
New data about amyloid precursor protein, or APP, a protein implicated in development of Alzheimer's disease, suggests it also may have a positive role -- directly affecting learning and memory during brain development.
Traffic jam in brain causes schizophrenia symptoms
Schizophrenia waits silently until a seemingly normal child becomes a teenager or young adult. Then it swoops down and derails a young life.
Building memories with actin
Memories aren't made of actin filaments. But their assembly is crucial for long-term potentiation (LTP), an increase in synapse sensitivity that researchers think helps to lay down memories.
CSHL researchers unravel how a protein helps nerve cells recycle synaptic vesicles
Brain cells, or neurons, transmit electrical signals efficiently only when they recycle tiny cellular sacs that store signaling chemicals called neurotransmitters.
Protein linked to mental retardation controls synapse maturation, plasticity, CSHL team finds
A team of neuroscientists at Cold Spring Harbor Laboratory (CSHL) has demonstrated the mechanism by which a signaling protein found throughout the brain controls the maturation and strength of excitatory synapses, the tiny gaps across which the majority of neurons communicate.
New insight into Alzheimer's disease pathology
An Alzheimer's-related protein helps form and maintain nerve cell connections, according to a study published in the May 4 print issue of the Journal of Cell Biology and online at www.jcb.org.
UCR researchers propose minocycline as a promising drug for patients with Fragile X syndrome
A UC Riverside-led team of biomedical scientists has found that a readily available drug called minocycline, used widely to treat acne and skin infections, can be used to treat Fragile X syndrome, the most common inherited cause of mental impairment and the most common cause of autism.
The first autism disease genes
The autistic disorder was first described, more than sixty years ago, by Dr. Leo Kanner of the Johns Hopkins Hospital (USA), who created the new label 'early infantile autism'.
Stopping a receptor called 'nogo' boosts the synapses
New findings about a protein called the nogo receptor are offering fresh ways to think about keeping the brain sharp.
Short-term stress can affect learning and memory
Short-term stress lasting as little as a few hours can impair brain-cell communication in areas associated with learning and memory, University of California, Irvine researchers have found.
More Dendritic Spines Current Events and Dendritic Spines News Articles
|
Dendritic Spines by Rafael Yuste (Author) Most neurons in the brain are covered by dendritic spines, small protrusions that arise from dendrites, covering them like leaves on a tree. But a hundred and twenty years after spines were first described by Ramón y Cajal, their function is still unclear. Dozens of different functions have been proposed, from Cajal's idea that they enhance neuronal interconnectivity to hypotheses that spines serve as plasticity machines, neuroprotective devices, or even digital logic elements. In Dendritic Spines, leading neurobiologist Rafael Yuste attempts to solve the "spine problem," searching for the fundamental function of spines. He does this by examining many aspects of spine biology that have fascinated him over the years, including their structure, development, motility, plasticity,... | |
 |
A Proteomic Approach on Synapse Formation: Molecular Mechanisms of EphrinB Signaling in Dendritic Spine Formation by Stefan Weinges (Author) Synapses are essential for the brain's normal function such as the brain's ability to transfer, process and store information. Synapses are thus constantly generated and degraded. To form a new synapse, hair-like filaments on opposing nerve cells differentiate into mushroom-like dendritic spines. Information transfer between nerve cells is then possible through these spines. However, the mechanisms that control this conversion of a thin filament into a functional dendritic spine have until now remained a mystery. Stefan Weinges has now succeeded in unravelling one of these complex mechanisms and identified the molecular players involved in synapse formation using a novel proteomic approach. To achieve this, he concentrated his investigations on a specific group of receptors and their... |
 |
Structural Plasticity of Dendritic Spines: A Computational Study by Muhammad Dur-e-Ahmad (Author) The geometry of a dendritic spine influences the dynamics of calcium in the spine and is regulated during synaptic plasticity. For instance, a moderate rise in calcium can cause elongation, while a very large increase in calcium causes fast shrinkage and the eventual collapse of a spine. In this book, we presented computational models for the calcium mediated spine-stem restructuring. This expansion and shrinkage depends on the frequency of the synaptic input to a spine as well as the activation of the calcium channels located on the spine head membrane. We are using computational studies to investigate the changes in spine density and structure for a variety of synaptic inputs of different frequencies. In particular, we are using the models to investigate... |
|
Motherhood and the hormones of pregnancy modify concentrations of hippocampal neuronal dendritic spines [An article from: Hormones and Behavior] by C.H. Kinsley (Author), R. Trainer (Author), G. Stafisso-Sandoz (Author), Quad (Author) This digital document is a journal article from Hormones and Behavior, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: Short-term fluctuations in steroid hormones such as estradiol (E"2) and progesterone (P) can affect the concentration of hippocampal dendritic spines in adult, cycling nulliparous female rats. Pregnancy is characterized by a significantly longer duration of substantially elevated E"2 and P compared to the estrous cycle. Thus, even greater changes than those reported during estrus may be evident. In two experiments, we examined the extent to which reproductive and hormonal state altered the concentration of apical... | |
![Dissociation between extension of the sensitive period for avian vocal learning and dendritic spine loss in the song nucleus lMAN [An article from: Neurobiology of Learning and Memory]](http://ecx.images-amazon.com/images/I/51T0MTGZBVL._SL160_.jpg) |
Dissociation between extension of the sensitive period for avian vocal learning and dendritic spine loss in the song nucleus lMAN [An article from: Neurobiology of Learning and Memory] by J.E. Heinrich (Author), K.W. Nordeen (Author), E.J. Nordeen (Author) This digital document is a journal article from Neurobiology of Learning and Memory, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: Several instances of early learning coincide with significant rearrangements of neural connections in regions contributing to these behaviors. In fact developmentally restricted learning may be constrained temporally by the opportunity for experience to selectively maintain appropriate synapses amidst the elimination of exuberant connections. Consistent with this notion, during the normal sensitive period for vocal learning in zebra finches (Taenopygia guttata), there is a decline in the density of... |
 |
Dendritic Spines: Biochemistry, Modeling and Properties (Neuroscience Research Progress) by Louis R. Baylog (Editor) A dendritic spine (or spine) is a small membranous protrusion from a neuron's dendrite that typically receives input from a single synapse of an axon. Dendritic spines serve as a storage site for synaptic strength and help transmit electrical signals to the neuron's cell body. Most spines have a bulbous head (the spine head), and a thin neck that connects the head of the spine to the shaft of the dendrite. The dendrites of a single neuron can contain from thousands up to a few hundred thousand spines. In addition to spines providing an anatomical substrate for memory storage and synaptic transmission, they may also serve to increase the number of possible contacts between neurons. This book presents new information in this area of research. |
|
|
Significant life events and the shape of memories to come: A hypothesis [An article from: Neurobiology of Learning and Memory] by T.J. Shors (Author) This digital document is a journal article from Neurobiology of Learning and Memory, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: Much has been said about how significant life events modulate our response to stimuli that are integral to those events. However, we know less about the more general consequences of these events, that is, how they affect subsequent learning abilities that are seemingly irrelevant to the initial event. Here, it is proposed that significant life events, most often stressful in nature, alter future learned responses by inducing nonspecific and persistent changes in neuroanatomical structures. These... |
|
|
Fragile X mental retardation protein levels increase following complex environment exposure in rat brain regions undergoing active synaptogenesis [An article from: Neurobiology of Learning and Memory] by S.A. Irwin (Author), C.A. Christmon (Author), A.W. Grossman (Author), Galvez (Author) This digital document is a journal article from Neurobiology of Learning and Memory, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: Fragile X mental retardation protein (FMRP), which is absent in fragile X syndrome, is synthesized in vitro in response to neurotransmitter activation. Humans and mice lacking FMRP exhibit abnormal dendritic spine development, suggesting that this protein plays an important role in synaptic plasticity. Previously, our laboratory demonstrated increased FMRP immunoreactivity in visual cortex of rats exposed to complex environments (EC) and in motor cortex of rats trained on motor-skill tasks compared... |
|
Pharmacology of Psychotomimetic and Psychotherapeutic Drugs. Annals of the New York Academy of Sciences Volume 66 Article 3 by Seymour, ed Kety (Author) |
| © 2009 BrightSurf.com |