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Baby neurons glue new memories

New findings suggest a hypothesis for a much-debated question in neuroscience : what exactly is the role of new neurons born in the adult human brain? These brain cells may help link memories of events that occurred within a week or two of each other, a paper published in Neuron reports. "It's really novel, and I think it's quite informative," said behavioral neuroscientist linkurl:Andrea Chiba;http://neurograd.ucsd.edu/faculty/detail.php?id=21 of the University of California, San Diego, who w

By | January 28, 2009

New findings suggest a hypothesis for a much-debated question in neuroscience : what exactly is the role of new neurons born in the adult human brain? These brain cells may help link memories of events that occurred within a week or two of each other, a paper published in Neuron reports. "It's really novel, and I think it's quite informative," said behavioral neuroscientist linkurl:Andrea Chiba;http://neurograd.ucsd.edu/faculty/detail.php?id=21 of the University of California, San Diego, who was not involved in the work. linkurl:Fred Gage;http://www.salk.edu/faculty/faculty_details.php?id=23, a neuroscientist at the Salk Institute in La Jolla, Calif., published a linkurl:controversial study;http://www.ncbi.nlm.nih.gov/pubmed/9547229?ordinalpos=60&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSumin in 1998 identifying the formation of new neurons in the adult hippocampus, a brain region associated with memory. Til then, neuroscience dogma had held that humans are born with all of the neurons they will ever have. But the function of these newly formed cells has never been identified. In the current study, Gage and his colleagues built a computational model to capture how neurons form, make connections, and integrate into existing brain circuitry. The team modeled the dentate gyrus, the area of the hippocampus where these cells are generated, as a network with multiple layers of different types of cells, only one of which can grow new brain cells. When a neuron fires, it sends information to other neurons in the circuit, which also fire if they receive enough stimulation. New neurons take fewer input signals from other cells to fire. Over time, each cell's firing pattern comes to reflect the inputs they receive, Gage said. Researchers have proposed many theories to explain the role of young neurons in the dentate gyrus, but this one is the first to convincingly bring together neurophysiological properties and knowledge about the structure and anatomy of hippocampal tissue, Chiba said. New neurons are hyper-excitable, firing at the slightest stimuli and forming connections with each other; more mature nerve cells, on the other hand, are more discriminating. This hair-trigger response allows newborn brain cells to link events and memories that happen around the same time, a phenomenon called pattern integration, Gage said. Mature cells, by contrast, help pick out differences between separate events. After about a week or two, the young brain cells mature, join established neural circuitry and become less excitable. Yet clusters of neurons that "grew up" around the same time still retain the memories forged in their youth. So when you remember your high school prom, the neurons that were newly formed at that time fire, also bringing back memories of final exams from the week after. Memories of college and high school graduation, by contrast, will feel distinct, because the neurons that store each of those memories were born and matured at different times. The next step, said Chiba, is to test the model's hypothesis in mice and rats. By labeling newly formed brain cells with a fluorescent marker molecule, researchers can track how neurogenesis affects the animals' ability to perform pattern integration tasks, Gage said. Diseases such as Huntington's and Alzheimer's also have a side effect of reducing the formation of new neurons, so understanding adult neurogenesis could help researchers devise new therapies, he added.
**__Related stories:__***linkurl: Growing a new antidepressant;http://www.the-scientist.com/article/display/52980/
[1st April 2007]*linkurl: Neurogenesis happens in humans, too;http://www.the-scientist.com/news/display/52849/
[15th February 2007]*linkurl: Signaling neurogenesis;http://www.the-scientist.com/article/display/53906/
[1st December 2007]
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Avatar of: OLE ISACSON

OLE ISACSON

Posts: 1

January 28, 2009

This article in The Scientist states: ?So when you remember your high school prom, the neurons that were newly formed at that time fire, also bringing back memories of final exams from the week after. Memories of college and high school graduation, by contrast, will feel distinct, because the neurons that store each of those memories were born and matured at different times.? \n\nUnfortunately, the above interpretation of adult hippocampal function from continued neurogenesis, is exactly wrong. The above statement is a confusion inadvertently created by the adult neurogenesis field in the public. One wishes more clarity: -- It is the ever changing small ?hippocampus? brain region, with it?s organizing of sensory inputs and by its outputs, that creates the memory paths and learning related processes primarily in the surrounding vast adult cerebral cortex of the brain. The cells in the huge expanse of the adult cerebral cortex were not born at the ?high-school graduation? and so they do not remember things because they were all born around that time. Instead, such cerebral cortex brain cells are activated to store longer-term memory from hippocampal connections and signals, but they were born much earlier. \n\nIn addition, the well-known findings of ?excitability? or better receptive fields of newborn neurons in the hippocampus is similar in principle to the findings in the olfactory bulb, where newborn neurons also show better responses than mature neurons (1-5). The interpretation is the same: newborn neurons, in receiving some order of organized sensory information, are more capable of receiving and forwarding (than older hippocampal neurons) the information to other more permanent neurons in the brain. The would make sense: -- The biological expense of continuously building in new neurons into the relatively small hippocampus or the olfactory bulb would give the entire brain function a boost for sensory based learning and to store long-term memories elsewhere ? not a permanent memory trace within the hippocampus itself.\n\nReferences:\n\n1. Schmidt-Hieber, C., Jonas, P. & Bischofberger, J. Enhanced synaptic plasticity in newly generated granule cells of the adult hippocampus. Nature 429, 184?187 (2004).\n2. Snyder, J. S., Kee, N. & Wojtowicz, J. M. Effects of adult neurogenesis on synaptic plasticity in the rat DG. J. Neurophysiol. 85, 2423?2431 (2001).\n3. Wang, S., Scott, B. W. & Wojtowicz, J. M. Heterogenous properties of dentate granule neurons in the adult rat. J. Neurobiol. 42, 248?257 (2000).\n4. Magavi, S.S.P. et al. (2005) Adult-born and preexisting olfactory granule neurons undergo distinct experience-dependent modification of their olfactory responses in vivo. J. Neurosci. 25, 10729?10739\n

January 28, 2009

Brain line of palm print called head line separated from life line indicates an increased activity of neurons by genetic inheritance.If a branch is sent to Jupiter mount ,the best efficiency is indicated.The double head line indicating the duality character of feminine like poetic romantic ,imaginative faculty is indicated by the lower line and practically a male domination is inherited by the upper line which may be found to be noticed due to new born neuron glue which was observed in the case of Count Loiuse Hamon ,cheiro ,the the great palmist .\nIn one of typical cases lunar rays are guiding for a duality character one man lived as a man for first fouteen lunar days and lived as a woman on the second 14 lunar days an interesting neuron shifted oscillation indicating strange quark dynamics of neurons.\nNeuron behaviour is delayed by the interactive Rahu and kethu as per our research activity carried out at oxford astro genetics dept.\nOptic lattices interefered for asymptotic free ejections :\nA very important conclusion has been arrived at by Oxford astro physics ?Hubble nanotech group in understanding the asymptotic freedom vanishing at +/-1 realised at infinite distance by applying mathematical theory on asymptotic freedom in space domains in understanding evolution of shadow concave down and concave down projections out of solar and lunar rays that take part in delayed neuron behavior which may give a clue on strange asymptotic freedom and ejections inherited by the oscillation optical lattices as Rahu and Kethu for chandrayan observation.This theory may please be put on record as 2009 astronomy contributions by the team of KNSK Engineering college nano tech group ,Anna University. member S.Nandakumar along with Hon.Roger davies ,oxford astro physics group under Hubble-nasa collaboration.\nThanking you \nSankara velayudhan Nandakumar

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