Penelitian begini sekarang ini lazimnya dibikin oleh orang kafir, di negeri
kafir dan bukan di Kairo atau di Jeddah..
Orang Islam sih lebih asyik zikir dan tunggang tunggik lima kali seharai atau
saling berbunuhan karena alasan agama?? ..
Islam itu, saya bilagn dan saya ulang adalahl aknat buat ummat manusia,a rtinya
buat orang islamsendiri.
Scientists Identify Machinery That Helps Make Memories
ScienceDaily (Nov. 1, 2008) — A major puzzle for neurobiologists is how the
brain can modify one microscopic connection, or synapse, at a time in a brain
cell and not affect the thousands of other connections nearby. Plasticity, the
ability of the brain to precisely rearrange the connections between its nerve
cells, is the framework for learning and forming memories.
Duke University Medical Center researchers have identified a missing-link
molecule that helps to explain the process of plasticity and could lead to
The discovery of a molecule that moves new receptors to the synapse so that the
neuron (nerve cell) can respond more strongly helps to explain several
observations about plasticity, said Michael Ehlers, M.D., Ph.D., a Duke
professor of neurobiology and senior author of the study published in the Oct.
31 issue of Cell. "This may be a general delivery system in the brain and in
other types of cells, and could have significance for all cell signaling."
Ehlers said this could be a general way for all cells to locally modify their
membranes with receptors, a process critical for many activities -- cell
signaling, tumor formation and tissue development.
"Part of plasticity involves getting receptors to the synaptic connections of
nerve cells," Ehlers said. "The movement of neurotransmitter (chemical)
receptors occurs through little packages that deliver molecules to the synapse
when new memories form. What we have discovered is the molecular motor that
moves these packages when synapses are active."
When neurons fire at the same time, their connections strengthen and a person
can associate certain features. "Once you have heard someone's name, seen his
face, where he was standing, all these features can be bound into a unified
packet of information – a percept – and at a very cellular level this occurs by
strengthening synaptic connections between co-active neurons," said Ehlers, who
is also a Howard Hughes Medical Investigator.
To learn and make new associations, the brain alters the strengths of the
synapses' electrical inputs onto cells that compute these features. Scientists
studied the hippocampus, where memories form, but this machinery could operate
in other brain areas.
"One of earliest changes in Alzheimer's disease is synapse dysfunction, so this
molecule might be a new target for that disease," he said. "Abnormal movement
of receptors may be implicated in brain development, in autism." He said the
molecule potentially is involved "in the abnormal electrical activity of
epilepsy and the overactive brain pathways of addiction."
In a series of biochemistry and microscopic imaging experiments, Ehlers and
colleagues found that the myosin Vb (five-b) molecule in hippocampal neurons
responded to a flow of calcium ions from the synaptic space by popping up and
into action. One end of the myosin is attached the meshlike actin filaments so
it can "walk" to the end of the nerve cells where receptors are. On its other
end, it tows an endosome, a packet that contains new receptors.
"These endosomes are like little memories waiting to happen," Ehlers said.
"They are reservoirs of neurotransmitter receptors that brain cells deploy to
add more receptors to a particular synapse. More receptors equals stronger
Electrical impulses cause one nerve cell to dump its neurotransmitter, in this
case, glutamate, into the small space between neurons (the synapse), which
activates neurotransmitter receptors on the receiving side. These are ion
channels that open in response to neurotransmitter and generate the electrical
When the scientists blocked myosin in single cells, this stopped the addition
of new receptors and prevented electrical impulses from getting stronger,
showing that myosin is essential to enhancing nerve cell connections.
"This is a very basic cellular mechanism of brain plasticity. It is likely
fundamental to brain development and disease," Ehlers said. "The myosin Vb
molecule gives us a new way to think about designing therapies for treating
memory loss, psychiatric disease and brain development."
Other authors included Zhiping Wang and Ian G. Davidson of the Duke Department
of Neurobiology and the Howard Hughes Medical Institute (HHMI); Jeffrey G.
Edwards, Nathan Riley and Julie A. Kauer of the Department of Molecular
Pharmacology, Physiology, and Biotechnology at Brown University; D. William
Provance Jr., Ryan Karcher and John A. Mercer of the McLaughlin Research
Institute in Great Falls, Montana; and Xiang-dong Li and Mitsuo Ikebe of the
Department of Physiology, University of Massachusetts Medical School. The work
was supported by grants from the National Institutes of Health and the HHMI.
Adapted from materials provided by Duke University Medical Center.
Need to cite this story in your essay, paper, or report? Use one of the
Duke University Medical Center (2008, November 1). Scientists Identify
Machinery That Helps Make Memories. ScienceDaily. Retrieved November 2, 2008,
from http://www.sciencedaily.com /releases/2008/10/081030123821.htm
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