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[TD][h2]Accepted Model for Brain Signaling Flawed.[/h2][B]A new study out January 10 in the journal Science turns two decades of understanding about how brain cells communicate on its head. The study demonstrates that the tripartite synapse -- a model long accepted by the scientific community and one in which multiple cells collaborate to move signals in the central nervous system -- does not exist in the adult brain.[/B][/TD]
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[TD][QUOTE][IMG]http://images.sciencedaily.com/2013/01/130110142125.jpg[/IMG][/QUOTE][/TD]
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[TD]"Our findings demonstrate that the tripartite synaptic model is incorrect," said Maiken Nedergaard, M.D., D.M.Sc., lead author of the study and co-director of the University of Rochester Medical Center (URMC) Center for Translational Neuromedicine. "This concept does not represent the process for transmitting signals between neurons in the brain beyond the developmental stage."
The central nervous system is home to many different cells. While neurons tend to garner the most attention, it is only recently that the function of the brain's other cells have been fully appreciated. Glial cells known as astrocytes, for example, had long been considered mainly the "glue" that helps hold all the other cells in the central nervous system in place. Scientists now understand that that these cells are essential to maintaining a healthy environment in the brain by helping carry out functions such as removing waste.
"Neurons are like a racing car," said Nedergaard. "While the driver gets all the credit, there are often 20 people behind the scenes that are optimizing his or her success."
However, when it comes to moving signals between neurons in the brain it turns out that the scientists may have vastly exaggerated the role of the astrocyte.
Neurons are connected to each other via axons or "arms" that extend from the cell's main body. Communication between neighboring neurons takes place where axons meet other nerve cells -- called a synaptic juncture -- when an electrical charge causes chemicals called neurotransmitters or glutamate to be released by one cell and "read" by receptors on the surface of the opposite. The two cells do not actually touch, so the chemicals messages must pass through a gap in the synaptic juncture. The space around this gap is insulated by astrocytes.
Under the tripartite synapse model, both astrocytes and neurons were believed to play a role in the "conversation" between cells. This understanding was largely based on animal models which showed active receptors and neurotransmission between not only the nerve cells but also the nearby astrocytes.
Specifically, a key neurotransmission receptor called metabotropic glutamate receptor 5 (mGluR5) was observed to be present and active in astrocytes at the synaptic juncture. It was also observed that when the mGluR5 receptor was activated, the astrocytes would release chemical transmitters that were in turn read by the nerve cells. These findings led to the conclusion that astrocytes must in some manner modulate the signaling process between brain cells.
While this model has held sway for decades, scientists have long been frustrated by their inability to influence this process by targeting it with drugs.
"If this concept was correct, it should have given rise to a clinical trial by now," said Nedergaard. "It has not, which tells us that with so many labs work on this for 20 years that there must be something wrong."
One of the barriers to understanding precise mechanics of passing signals from one neuron to another has been the inability to observe this process in the adult brain. The tripartite synapse model was based -- in part -- by examining the activity in the brains of very young rodents. Adult rodents could not be similarly studied because the synapses in the brain would die before they could be fully analyzed. This ultimately led to the presumption that the signaling process that was witnessed in the young brain carried over to adulthood.
Collaborating with researchers at the University of Rochester's Institute of Optics, Nedergaard and her team developed a new 2-photon microscope that enables researchers to observe glia activity in the living brain. Using both this method and by analyzing the gene and protein expression in the brain the researchers discovered that the mGluR5 largely disappear in the glial cells of adult mice meaning that these cells do not directly respond to synaptic neuronal signalling, thus calling into question the concepts that drive most of ongoing research in the field.
"The process of neuron-glial transmission as conceived by the tripartite synapse model appears to just be a simplistic signaling pathway that 'teaches' the synapse how to behave," said Nedergaard. "Once the brain matures, it goes away."[/TD]
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[TD][B]Journal: [/B] Wei Sun, et al. Glutamate-Dependent Neuroglial Calcium Signaling Differs Between Young and Adult Brain. Science, 11 January 2013: Vol. 339 no. 6116 pp. 197-200 DOI: [URL]http://dx.doi.org/10.1126/science.1226740[/URL][/TD]
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[TD][B]SOURCE: [/B] [URL]http://www.sciencedaily.com/releases/2013/01/130110142125.htm[/URL][/TD]
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Holy SHIT
oh shit
[quote]does not exist in the adult brain.[/quote]
Everything I've ever been taught about how the brain works is now worthless
Cool, I hope this leads to all new sorts of stuff
Fascinating; but then how does the adult brain really work?
[QUOTE=ironman17;39172198]Fascinating; but then how does the adult brain really work?[/QUOTE]
Mass effect fields.
[quote]The tripartite synapse model was based -- in part -- by examining the activity in the brains of very young rodents. Adult rodents could not be similarly studied because the synapses in the brain would die before they could be fully analyzed. This ultimately led to the presumption that the signaling process that was witnessed in the young brain carried over to adulthood.[/quote]
That's the exact same mistake Galen made with the gorilla jaw. You'd have thought we'd learn from past mistakes.
On a more upbeat note, could this be why adults lose the neuro-plasticity that children have? And could we perhaps recover it?
This is what's amazing about science. Always finding out new things, even if you realize that you were wrong for 20 years.
[QUOTE=ironman17;39172198]Fascinating; but then how does the adult brain really work?[/QUOTE]
magic
[QUOTE=ironman17;39172198]Fascinating; but then how does the adult brain really work?[/QUOTE]It doesn't, it only works because you think it works.
[QUOTE=ExplodingGuy;39172674]It doesn't, it only works because you think it works.[/QUOTE]
So if you stop thinking, it stops working...
Wait a second.
It's probably organic transistors or something; I'm sure there was also a chemical element with ions being transferred, but I don't know jackshit about brain science, apart from the fact it can't exert directed kinetic forces.
Everything I thought was [i]wrong[/i].
I remember school trying to tell me that weed would cause some of these to stop being receptive or some shit and inhibit sensations during sex
While this flips our understanding on its head, this could lead to some amazing clinical drugs (amnesiacs, memory enhancers, etc). I may be blatantly wrong, but it sounds to me like a newer, more thorough understanding of the adult brain can mean major improvements in neuroscience.
Hours of work and revision in college useless from this point forward in my life.
Let's cut to the important part; does this mean I get like, five more points tacked onto my Bio final exam?
My guess is that while the brain is young and creating it's structures, it's constantly taking cues from the environment as to how to develop. Once it reaches a certain age, new neural connections and pathways are still made, but in a continued pattern based on biological history rather than outside stimuli. The neurotransmitters may only be valuable to the development of aspects of the developing brain, which might explain why antidepressants and various drugs are so dangerous to adolescents and young adults.
It isn't saying neurons and chemical synapses are wrong, its just saying that astrocytes don't directly participate in neurotransmission in adults, which is only part of the 'accepted model'. This is all interesting and important, of course, but it isn't saying the whole model is wrong and I feel that most of you are interpreting it that way.
[QUOTE=QwertySecond;39172473]That's the exact same mistake Galen made with the gorilla jaw. [B]You'd have thought we'd learn from past mistakes.[/B]
On a more upbeat note, could this be why adults lose the neuro-plasticity that children have? And could we perhaps recover it?[/QUOTE]
It said in the article at the time there was no way to observe adult neurons because they would die to quickly.
The only way to further understand what we know is to challenge it. And sometimes, assumptions must be made. However there should have been more emphasis on it being a theory, because I was constantly taught it as if it was 100% true.
[editline]10th January 2013[/editline]
[QUOTE=nessman;39173007]I remember school trying to tell me that weed would cause some of these to stop being receptive or some shit and inhibit sensations during sex[/QUOTE]
I believe what you're talking about is dopamine over-stimulation.
How the fuck would weed do that
[QUOTE=ironman17;39172198]Fascinating; but then how does the adult brain really work?[/QUOTE]
carbon nanotubes
Good thing I didn't learn anything in Psychology class :v:
How will this effect that whole "X amount of years until we replicate the brain" thing?
[QUOTE=ironman17;39172708]I don't know jackshit about brain science, apart from the fact it can't exert directed kinetic forces.[/QUOTE]
[B][I]YET[/I][/B]
[QUOTE='[LOA] SonofBrim;39173025']While this flips our understanding on its head, this could lead to some amazing clinical drugs (amnesiacs, memory enhancers, etc). I may be blatantly wrong, but it sounds to me like a newer, more thorough understanding of the adult brain can mean major improvements in neuroscience.[/QUOTE]
i don't see why you're getting agrees when you basically made the most redundant statement ever.
"a newer, more thorough understanding of the adult brain can mean major improvements in neuroscience."
translated:
"major improvements in neuroscience can mean major improvements in neuroscience."
:v:
what an amazing discovery
[QUOTE=ExplodingGuy;39172674]It doesn't, it only works because you think it works.[/QUOTE]
Much like Ork weaponry from 40k? :v:
[QUOTE=yawmwen;39177075]i don't see why you're getting agrees when you basically made the most redundant statement ever.
"a newer, more thorough understanding of the adult brain can mean major improvements in neuroscience."
translated:
"major improvements in neuroscience can mean major improvements in neuroscience."
:v:[/QUOTE]
*Application and use of neuroscience, I apologize for any confusion. Although when you put it that way, improvements in neuroscience does in fact mean improvements in neuroscience, hense the agrees. :v:
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