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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.
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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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.
It's not really thought that the brain uses quantum computing, but rather massively parallel computing to do its work. This is that tactic taken by researchers of chemical computers. This doesn't really change the idea. What it does mean is two things that I see:
All in all, this is pretty cool, although it might not mean anything. Just because you can get the cells to trigger neurons by making thenm release calcium doesn't mean they do this normally. All cells have calcium ions in them, the question is do the glial cells release them under normal conditions? That's what really needs to be investigated at this point.
"I may not have morals, but I have standards." - Marcin
"I may not have morals, but I have standards."
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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