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Use All Your Brain, Not Only Neurons?
SEWilco writes: "Iowa State researchers found evidence that glial cells communicate in the brain. Previously it was thought that the neurons were active, but glial cells were only structural and nourishment objects. Apparently glial cells can influence neighboring neurons at least through glutamate signals. Details in the Proceedings of the National Academy of Sciences. Maybe we still have a little more to learn about biology." I know, it's my second 'science question' headline of the day, but heck, most science headlines should end with a question mark.
Chmrr,
The material that covers the axons of the neurons is myelin, not glial cells (see http://www.dictionary.com/cgi -bin/dict.pl?term=myelin.
Myelin allows the chemical-electrical transmission to happen in a more "productive" manner. Faster and better neurotransmissions from one neuron to the next.
Glial cells are the support structure, but myelin is separate. Glial cells are not neurons. I guess now their finding that Glial cells do more than just support and can influence neurons cells in certain ways. If you ask me this isn't that extrodinary, because the more glial cells you have around the neurons, the better off things are so its obvious the glial cells influence neurons in some way. I guess we're just getting more knowledgable about how.
Maybe by the time I get this post in someone will have explained it better but I'll add my 2 cents anyways and expand on Chmrr's explanation. The computer mouse analogy works well. The mouse is a neuron. The big plasic chunk is the body of the neuron, and the tail is the axon. On the body are little strands which extend out to "touch" the axons of other neurons. When the neuron gets enough impulses from other neurons through the little strands (called dendrites) the neuron body fires a charge down the axon (mouse cord) off to one other neuron.
If the head had grown up attached to a body, the basic thought patterns and capacities would be similar, though would change in ways similar to those who grow up normal, then become quadraplegic through accident. A head in a jar (BIV for you h.p.o readers) raised that way would likely think in very different ways, though.
" I'd like to know if there's evidence that glial cells also have functional calcium uptake pumps and if their level of calcium fluctuates with blood level or remains constant..."
Glial cell (C6 glioma) calcium levels fluctuate with that of the external medium. Changes of a few mM produce cytosolic changes on the order of 10's of nM (J. Phyiol. several years ago). In vivo...who knows?
"While this is interesting news, it's certainly not true that we ever thought of glia as (in the
words of the press release) "little more than glue." "......
Before 1950, some researchers confused the extracellular space in the brain with glial cells. The 'space' was actually cellular.
Unfortunately, glial electrophysiological characteristics did not, do not, lend themselves to sustained, fundable study. i.e., where's that action potential? This glial cell calcium story, and the many other glial calcium studies, may help change some perceptions.
I agree with you: current thinking is astrocytes are good for you when you're developing your brain (providing pathways to guide neurons to 'final' destinations) but 'bad', if you're an adult who has a penetrating nerve-killing injury.
Its true, he had twice as many glial cells, and at the time of his death, nobody knew why or if it had an impact on his intelligence.
This should not be that sensationalistic. There has been speculation for quite some time now that glial cells do more than "hold stuff together"
The major functions of glial cells have long been known to be "supportive" of the communication functions of neurons. To accomplish this, there are several types of glial cells in the central neurvous system (CNS). Some of them (Oligodendrocytes in the CNS and Schwann Cells in the peripheral nervous system (PNS) form myelin sheaths, which are insulative wrappings around axons that allow the axons to conduct information more rapidly and in isolation from each other to prevent cross talk. Other types of glial cells regulate the composition of extracellular fluids, assist neurons in metabolic activities, and participate in various humoral functions within the CNS.
In development, glial cells provide critical support functions for neurons such as guiding developing neurons to the right places in the brain and at the right time as well as functioning as a storehouse for neurotransmitter precursors and energy reserves for active neurons.
It has long been known that glial cells regulate the amount of neurotransmitter in the synapse by uptake of neurotransmitter and buffering of Calcium in the synapse as well which is critically important to synaptic release. Signaling in the CNS could certainly be influenced by the speed at which available neurotransmitter is taken up and also calcium. Many glial cells also have receptors for neurotransmitters and may play a role in the co-incident release of various traditional and non-traditional neurotransmitters or neuromodulators.
It should also be noted that glial cells also play a very intimate role in the recycling of neurotransmitters such as glutamate, where they convert glutamate into other metabolites that neurons can use for metabolism or neurotransmission. This too can influence cell state and thus signalling.
Finally there is some limited evidence on the electron microscopic level that there are actual synapses on neurons from glia. If true this indicates a more direct and speedy communication between glial cells and neurons.
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It has been speculated that quantum computing effects may occur in the brain. However, as I understand it, the current conventional wisdom is that such effects are minimal at best, and do not impact on the overall result of brain function.
Unfortunately, we will never know until we take a very smart person and run their brain through a particle accelerator and watch the effect as it smashes into a solid block of steel. Any volunteers?
Aah, change is good. -- Rafiki
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Thanks for the interesting reply. Of course it was foolish of me to say that we never thought of glia as inert...
current thinking is astrocytes are good for you when you're developing your brain (providing pathways to guide neurons to 'final' destinations) but 'bad', if you're an adult who has a penetrating nerve-killing injury.
Funny how often we have to fight against the fruits of evolution when trying to do unreasonable things like transplant organs, travel in microgravity, and live 140 years...
- Michael Cohn
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Hmm, most Neural Network models are based around a series of interconnected neurons. I wonder what impact this new discovery might have on them - maybe with glial cells modelled in software, and some hairy mathematics, our neural nets might become more powerful?
How do we get these glial cells to communicate with the airport antennas on my new G4 Cube so I can use my brain as a processor?
Does it occur to anyone that neural scientists are making too many assumptions?
For years I heard that the brain *never* regenerates cells. The brain cells that you're born with are the only ones you will ever get. Now, it is known that is completely wrong. The brain does have the ability to regenerate brain cells that are lost. I was always skeptical and I was not surprised that the brain happens to do what every organ in the body already does. I think it would be quite remarkable if the brain was unique in that way.
Now we find out that cells which the common wisdom classified as stuctural members turn out to actually have some communications functions built into them. I remember reading about this years ago, and I was skeptical about that too. At the very least, the structural cells would have *some* impact on neural activity, and therefore must be considered as part of the computational structure of the brain.
I'm not sure where it's coming from though. Neural science draws from other disciplines, including psychology and medicine. One could argue that both of those subjects are still in the process of hacking their way out of their unscientific origins. I wonder if the half-completed scientific revolution in those subjects is hindering progress in understanding the brain.
To be fair, artificial inteligence is also a contributer to neural science which is probably even farther in the dark ages than either psychology or medicine.
Disclaimer: my wife is a psychologist. My comments are not meant as flamage, so if you're getting mad, contact me so I can clarify what I mean.
If tits were wings it'd be flying around.
The article makes it sound like everything is in black & white. Those of us who are more experienced biologists know that it's really a gray matter.
I need a TiVo for my car. Pause live traffic now.
It should be noted that all cells communicate with nearby cells. This is an important part of our ontogeny (growth), and function. Therefore it's rather obvious that neurons communicate with glia cells at least somehow.
It should be noted that the glia cells do not necessarily perform any neural computation:
"Pathophysiological" means "unnatural". Anyhow, it might be just signaling that guides how the neurons or glia cells grow (during our ontogeny or afterwards). The changes in activation of the nearby neurons might be just a side effect, although it would nevertheless affect their computations, if the glutamate is actually released at postnatal (after birth) age (I understood that this is not known).- A novice artificial neural networks researcher who knows only very very little about neurobiology
I get it. It's the electromagnetic radiation from the hardware, that stimulates the glial cells, leading to a cascade of neuronal responses, fomenting the neuromuscular chain reaction that culminates in hitting the BID button on E-bay. No wonder the economists couldn't figure it out. They only assume rational utility maximizers.
Offered by physicist Penrose who says "I'm too stupid to figure out the complexity of the brain, so I'll confound things with mumbo-jumbo physics".
Do you think that a head in a jar would think in the same was [sic] as when it was attached to the rest of the body?
The short answer is yes. If the brain is still intact and provided with the proper nutrients, oxygen, etc. it should function no differently then before.
The lack of a body will mean the lack of any stimuli from the body. Thus the brain's 'intuitive senses' (i.e. 'gut feel') will no longer have any effect on the output of such a brain.
This seems similar to someone losing their hearing or sight. They still think the same way they just don't have as much input to use to think with.
Thus the correct way to think about a head in a jar is as a severely handicapped individual. And no doubt the personality of that brain would change over time. (But that's true of all brains.)
Since you said head in a jar I assume you mean that the eyes, ears, nose, mouth are still intact and functioning. If not, then we have the absense of these inputs, but the brain would still function the same way. But it would have no input to operate on. Sensory deprivation studies have shown that brains will create their own inputs, aka hallucinations. The person associated with that brain, experiencing massive sensory loss would probably go insane.
Steve M
Probably in a few years scientists will find that intestinal cilia are used as well...
That's why so many people have shit for brains.
The experiment involved artificially increasing levels of calcium in astrocytes (a type of glial cell) while monitoring adjacent neurons for signs of response to released neurotransmitters. Since the levels of calcium required were comparable to those found in the natural environment, the researchers concluded that glial cells may control neurotransmitter balance in the brain as well. I'd like to know if there's evidence that glial cells also have functional calcium uptake pumps, and if their level of calcium fluctuates with blood level or remains constant. Unfortunately, reading the full article requires a paid subscription...
While this is interesting news, it's certainly not true that we ever thought of glia as (in the words of the press release) "little more than glue." Glial cells produce the myelin sheathing that allows motor signals to travel rapidly from the brain to the extremities, and their signals are important to laying down the organization of different areas in the early months of brain development. They're also an important adversary when it comes to repairing nerve damage in the periphery. Severed nerves actually try to grow back along their established pathways, but the glial cells poison them (presumably to prevent inappropriate overgrowth). Learning to inhibit this process may be the key to restoring limbs that are paralyzed.
- Michael Cohn
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Go ahead, blame me... I voted for Nader!
I thought this looked familiar.
Murphy TH; Blatter LA; Wier WG; Baraban JM.
Rapid communication between neurons and astrocytes in primary cortical cultures.
Journal of Neuroscience, 1993 Jun, 13(6):2672-9.
Or, as Francis Crick puts it, the body is the mind. Any mind/body duality is more religious hocus-pocus than actual fact. Do you think that a head in a jar would think in the same was as when it was attached to the rest of the body?
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