The common view that nerves transmit impulses through electricity is wrong and they really transmit sound, according to a team of Danish scientists.

The Copenhagen University researchers argue that biology and medical textbooks that say nerves relay electrical impulses from the brain to the rest of the body are incorrect.

"For us as physicists, this cannot be the explanation," said Thomas Heimburg, an associate professor at the university's Niels Bohr Institute. "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."

Heimburg, an expert in biophysics who received his PhD from the Max Planck Institute in Goettingen, Germany — where biologists and physicists often work together in a rare arrangement — developed the theory with Copenhagen University's Andrew Jackson, an expert in theoretical physics.

According to the traditional explanation of molecular biology, an electrical pulse is sent from one end of the nerve to the other with the help of electrically charged salts that pass through ion channels and a membrane that sheathes the nerves. That membrane is made of lipids and proteins.

Heimburg and Jackson theorize that sound propagation is a much more likely explanation. Although sound waves usually weaken as they spread out, a medium with the right physical properties could create a special kind of sound pulse or "soliton" that can propagate without spreading or losing strength.

Read more: http://www.cbc.ca/technology/story/2007/03/09/science-nervessound-20070309.html

I really hate crap like this. Theoretical physicists who think they know more than any other type of scientist simply because they are …. (gasp and awe) ..... physicists! :eek: This is just another instance of people trying to generate some media buzz over nothing.

Heimburg and Jackson theorize that sound propagation is a much more likely explanation.
It’s not a “much more likely” explanation at all. Not even slightly. :bugeye:

Propagation of membrane potentials by salutatory conduction along axons (ie. electrical nerve impulses) is confirmed countless times every day all over the world via the endless scientific experiments and medical procedures that are based on that theory. Every level of biology (from the genetic level to the biochemical level to the cellular level to the whole organism level) confirms the electrical impulse theory.

And here’s the clincher…

Although sound waves usually weaken as they spread out, a medium with the right physical properties could create a special kind of sound pulse or "soliton" that can propagate without spreading or losing strength.
Oh I see. So in order to substantiate their unproven idea that nerve impulses are actually sound and not electrical in nature, they are invoking an unknown and theoretical set of physiological conditions that must be present in order for their theory to be correct! What absurd circular logic. :rolleyes:

Interesting stuff. It looks like Dr Heimburg has been researching this for a few years. It will be extremely interesting if his ideas lead to improvements in anaesthetic research.

Interesting stuff. It looks like Dr Heimburg has been researching this for a few years. It will be extremely interesting if his ideas lead to improvements in anaesthetic research.Glad to see you back here active. Perhaps you were in hospital with head injury?:confused:

Herk Rock is 110% correct. It is relatively simple to stick micro electrodes into axon and see the -70mV "resting potential" or observe that the concentration of Na+ ions has been reduced compared to the electrolyte outside.

When this neutral sound wave (a soliton of course) comes to a given point on the axon there is a sudden influx of the Na+ to the interior of the axon and often a slight "over shoot" to a few mV positive. The soliton wave can not pass again until the "sodium pump" restores the negative resting potential in the interior by pumping the Na+ back out (called the refractory period).

I wonder why the axon is refractory for a period in that no new soliton wave can travel down it?:rolleyes:

Take two asperin, get some more rest, and your brain should recover. - I sure hope so. - You are one of the best thinking and the hardest working posters here.

BTW I think Herk was excessively kind to those idiots. - I bet they do not even know that the first ELECTRICAL oscilloscope was invented two guys trying to measure the speed of those "soliton waves":(

It's already known how nerves work. These Danish scientists are wrong.
"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."Maybe because it's not so much an electrical current as it is a change in voltage. The heat produced would be so very small that they probably just failed to measure it correctly.

According to the traditional explanation of molecular biology, an electrical pulse is sent from one end of the nerve to the other with the help of electrically charged salts that pass through ion channels and a membrane that sheathes the nerves. That membrane is made of lipids and proteins.Yes. The traditional explanation has been proven and observed time and time again.

If it actually were sound instead of electrical potential, then why do anaesthetics such as benzocaine, which work by blocking the sodium channels , work the way they do? The whole purpose of the sodium channel is to regulate the voltage through ions.

Don't draw conclusions from the media article. I don't think it's an accurate representation of the work it's reporting on... at least, I can't reconcile it with the literature published by Thomas Heinberg.

This article seems to be the seminal work: On soliton propagation in biomembranes and nerves (http://www.pnas.org/cgi/reprint/0503823102v1)
More recent papers can be found here: Membrane Biophysics Group, Neils Bohr Institute, University of Copenhagen (http://membranes.nbi.dk/)

According to my limited understanding, they do not deny that electrical impulses are involved in nerve transmission. They do claim that they have suggestive evidence that solitons (structured sound waves) could be involved.

As far as i can tell, it's good science. They've followed through on some interesting observations and produced a testable novel theory.

It seems to me if this were true if a human were ever to encounter a specific frequency of sound, all their nerves would start firing at once causing a seizure of some sort.

BTW I think Herk was excessively kind to those idiots.
Well, I think it’s a bit harsh to label them as idiots. :)

And Pete makes a very good point – science journalism is frequently poor and seldom accurately reflects the science that is being reported. It's definitely a trap to judge science based on its media coverage.

It glanced at the PNAS paper that Pete identified as (apparently) the “seminal” on the subject. I have a neuroscience background but for the most part it was unintelligible to me. The subject matter is biophysics which mostly bears no resemblance to “wet” biology. It’s all a bunch of mathematical analyses of isolated lipids in non-physiological conditions, and purely theoretical extrapolations to living organisms. I couldn’t recognize anything that related to in vivo biology.

My overall impression is that it's just a whole lot of hand waving.

The subject matter is biophysics which mostly bears no resemblance to “wet” biology.
I find this slightly harsh. From my experience (I have an ongoing colloboration with one lab) biophysics experiments are not that different from biological ones. There is a difference in interpretation, though. The physicists usually try to derive a mathematical model from the measurements and often check these with theoretical physicists. While one could argue that biological systems are too complicated and so forth, however, I found some models quite helpful.

That being said, I cannot assess the relevance of the paper from the first glance, either...

My overall impression is that it's just a whole lot of hand waving.Do you think the handwaving is transverse or longitudinal?:)

Do you think the handwaving is transverse or longitudinal?:)Does not matter so long as it is shape preserving.

More seriously, perhaps I was too harsh, based on only a press report, without reading more than post 1's:

"...According to the traditional explanation of molecular biology, an electrical pulse is sent from one end of the nerve to the other with the help of electrically charged salts that pass through ion channels and a membrane that sheathes the nerves. That membrane is made of lipids and proteins.
Heimburg and Jackson theorize that sound propagation is a much more likely explanation. ..."

This seems to be stating something truely idiotic. Nerve impulses, are electric depolarization waves. They do have a "soliton constant shape" but so do many waves that have small dispersion, for example, the analogue voice signal in the elephone company's wires.

Hold the presses:
Billy T announces that the copper wires of telephone company are carrying "soliton sound waves" and that is a "much more likely explanation " than the conventional POV that they are electrical signals!:rolleyes:

Plus if nerve cells used sound waves wouldnt our reflexes be much much slower than they currently are considering sound moves a lot slower then electricity?