Posted on 03/08/2007 9:40:58 AM PST by LibWhacker
Danish scientists challenge the accepted scientific views of how nerves function and of how anesthetics work. Their research suggests that action of nerves is based on sound pulses and that anesthetics inhibit their transmission.
Every medical and biological textbook says that nerves function by sending electrical impulses along their length. "But for us as physicists, this cannot be the explanation. The physical laws of thermodynamics tell us that electrical impulses must produce heat as they travel along the nerve, but experiments find that no such heat is produced," says associate professor Thomas Heimburg from the Niels Bohr Institute at Copenhagen University.
Image: shows a biological membrane at its melting point. The green molecules are liquid, and the red are solid. Molecules of anesthetic reduce the number of red areas so that the sound pulse can no longer transport its signal. The nerve is anesthetized.
He received his Ph.D. from the Max Planck Institute in Göttingen, Germany, where biologists and physicists often work together – at most institutions these disciplines are worlds apart. Thomas Heimburg is an expert in biophysics, and when he came to Copenhagen, he met professor Andrew D. Jackson, who is an expert in theoretical physics. They decided to work together in order to study the basic mechanisms which govern the way nerves work.
Physics explains biology
Nerves are 'wrapped' in a membrane composed of lipids and proteins. According to the traditional explanation of molecular biology, a pulse is sent from one end of the nerve to the other with the help of electrically charged salts that pass through ion channels in the membrane. It has taken many years to understand this complicated process, and a number of the scientists involved in the task have been awarded the Nobel Prize for their efforts. But – according to the physicists – the fact that the nerve pulse does not produce heat contradicts the molecular biological theory of an electrical impulse produced by chemical processes. Instead, nerve pulses can be explained much more simply as a mechanical pulse according to the two physicists. And such a pulse could be sound. Normally, sound propagates as a wave that spreads out and becomes weaker and weaker. If, however, the medium in which the sound propagates has the right properties, it is possible to create localized sound pulses, known as "solitons", which propagate without spreading and without changing their shape or losing their strength.
The membrane of the nerve is composed of lipids, a material that is similar to olive oil. This material can change its state from liquid to solid with temperature. The freezing point of water can be lowered by the addition of salt. Likewise, molecules that dissolve in membranes can lower the freezing point of membranes. The scientists found that the nerve membrane has a freezing point, which is precisely suited to the propagation of these concentrated sound pulses. Their theoretical calculations lead them to the same conclusion: Nerve pulses are sound pulses.
Anesthetized by sound
How can one anesthetize a nerve so that feel ceases and it is possible to operate on a patient without pain? It has been known for more than 100 years that substances like ether, laughing gas, chloroform, procaine and the noble gas xenon can serve as anesthetics. The molecules of these substances have very different sizes and chemical properties, but experience shows that their doses are strictly determined by their solubility in olive oil. Current expertise is so advanced that it is possible to calculate precisely how much of a given material is required for the patient. In spite of this, no one knows precisely how anesthetics work. How are the nerves "turned off"? Starting from their theory that nerve signals are sound pulses, Thomas Heimburg and Andrew D. Jackson turned their attention to anesthesia. The chemical properties of anesthetics are all so different, but their effects are all the same - curious!
But the curious turned out to be simple. If a nerve is to be able to transport sound pulses and send signals along the nerve, its membrane must have the property that its melting point is sufficiently close to body temperature and responds appropriately to changes in pressure. The effect of anesthetics is simply to change the melting point – and when the melting point has been changed, sound pulses cannot propagate. The nerve is put on stand-by, and neither nerve pulses nor sensations are transmitted. The patient is anesthetized and feels nothing.
Source: University of Copenhagen
Source of sound pulses? Frequency? Have they been measured? Can we make our own and interfere with them? So many questions!
O-O-O-O-M-M-M-M-H-H
Well that explains why loud Hip-Hop cars in traffic gets on my nerves............
All science is physics.
Makes one wonder if screaming when in pain might be a way the body tries to mitigate the pain by overriding the "sound waves" in the nerve paths.
Thanks. Very interesting!
"Extraordinary claims require extraordinary proof."
Until then, this article is probably BS.
Maybe this will help to explain why the sound of Shrillery's voice makes me feel actual physical pain -- she must be able to activate my nerves and influence the sound that is transmitted through them!
Maybe something like this could prove useful against the enemy in battle? In addition to helping "us" understand anesthetics, it could help us figure out new ways to induce pain in the enemy at a distance.
bttt
Sounds like they haven't actually proved this. It occured to me that the lack of heat could also be explained if it turned out that nerves are actually superconductors.
I'm not a physicist and I didn't stay at a Holiday Inn Express last night, but isn't my explanation as feasible as theirs? (Just trying to stir the pot!)
It should be relatively simple to test nerves for minute pressure changes in response to stimuli, shouldn't it? This theory appears to be relatively simple to confirm, to my non-scientific mind.
What?
A SCIENTIST, huh? Doesn't he know that sound waves produce heat too as they travel through a substance?
This statement is, unfortunately, usually made to stop discussion of a proposition that the speaker disagrees with. That means the speaker believes he has some prior knowledge about the proposition that he regards as strong evidence and does not want to hear anything to the contrary. I concede that not all propositions start with maximum entropy priors. So in this case, the speaker believes he has some special knowledge about the prior probability of the truth of the proposition.
But even with such special knowledge the "extraordinary claims" language is deeply imprecise.
From a Bayesian perspective, which admits prior probabilities, even a very strong and spiked prior probability for the truth of a proposition like "nerve impulses are transmitted electrically," changes VERY quickly with contrary evidence, given even one new fact. So if, for example, there is no evidence of the heat that ought to be given off via electrical transmission, that is a very significant contrary fact and the posterior probability distribution after that fact changes the strong prior very significantly.
So "extraordinary proof" is almost a silly concept here. Of course, you want the contrary "fact" to be replicated. But once replicated, according to normal scientific standards (not double-dawg-dare extraordinary standards), that single fact changes the posterior probability profoundly.
The other evidence cited in the article, that is, the lipid solubility and it's correlation with the anesthetic properties of different molecules, is not a contrary fact--it's an alternate explanation for an observed phenomenon (nerve transmission). The existence of an alternate explanation would not change the posterior as much as a contrary fact. The existence of a viable, alternative explanation does, however shift the posterior probability.
So my point is, the "extraordinary claims" language is quite sloppy and really should play no role in scientific discussion. It's a rhetorical point to close-off inquiry, not a scientific point.
"Extraordinary claims require extraordinary proof."
Do you believe in God, Heaven and/or an afterlife?
Just askin'... ;)
All physics is math.
"It's a rhetorical point to close-off inquiry, not a scientific point."
hmmmmm ...
reminds me of the global warming non-debate.
Me too.
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