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Scientists Say Nerves Use Sound, Not Electricity
gazzarda writes "The CBC is reporting that a team of Danish scientists are claiming that nerve impulses are transmitted by sound and not electricity. 'The common view that nerves transmit impulses through electricity is wrong and that 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.'"
IAAANS (I am also a neuroscientist) and I'm with you on this. TFA sounds pretty crackpot to me. If they really had strong evidence for this it would be published in Nature, not Biophysical Journal.
NO CARRIER
On further review, it seems that the CBC article is total crap, but that the original paper isn't that far off the deep end. I admit that I don't know enough to really follow or critique the research, but it doesn't seem to be the crackpot theory that TFA implies. Nowhere, for example, does that paper say that nerves don't use electricity. In fact, the paper refers to "solitons" as a piezo-electric effect. They are merely proposing a new mechanism on top of previous theories, not trying to completely throw out all neuroscience to date.
To recap: Completely bogus headline, based on a completely bogus bit of popular science reporting, which itself is based on a possibly intriguing (but tentative) bit of original research. Nothing to see here.
I will say that their physics seems reasonable - one should understand that when we say "sound" there can be several meanings to that word. In the article, they are talking about piezo-electric pulses which I can visualise as a pressure wave that creates voltages between synapses (forgive me if I'm murdering the biology here ;-)). Imagine your usual piezo-crystal (a simple example is the one in a wristwatch) that vibrates (pressure waves) when a voltage is applied. Well, the reverse can also happen (this is used in some species of microphones). The way I visualize their model is that a piezo-electric soliton (if I remember my group theory, it's a sort of a quantized sound wave which persists without being destroyed by background noise because it has a topological quantum number asociated with it) travels between synapses leading to a voltage between them. Now, the pressure wave exists in the surrounding medium, which contains the ions in solution. So, at the most one can interpret these findings to mean that neural conduction is more like current in a superconducting wire than electroplating :D. This is the essence of their transport theory (as I understand it).
Another thing to note is that the article is not written as a maverick physicist would. It is written in a way that only a proper experimental physicist would - theory -> prediction -> experiment -> comparison. And the thing they are evaluating is actually the effect of anasthetics on neural transport. So, they are simply not claiming stuff as the news site falsely overhypes. I for one find this article fascinating even though biophysics is not my field.
I don't see how this translates to the sensationalist headline (although it's not the poster's fault, the linked site is a Canadian news site. The fact that it's Canadian is irrelevant :D, but the fact that it's a news site is rather telling. Also, they couldn't reach the authors for comments, which probably explains the awkward spin on the research.
IAAANS (I am also a neuroscientist) and I'm with you on this. TFA sounds pretty crackpot to me. If they really had strong evidence for this it would be published in Nature, not Biophysical Journal.
I'm afraid Nature is rather conservative in that respect and their editorial policy is at least partly based on maintaining or raising their impact factor (it is a highly profitable publication after all). The only way they can do that is by ensuring that only articles that are likely to be frequently cited in the future are published (that's the critical number that figures in the calculation of impact factor). As a result, the argument that any ground-breaking research would be automatically published in Nature is simply not true. Quite the contrary in fact. Now, before people mistake this for flamebait :P, I'm simply saying that Nature prefers the "wait-and-watch" routine, sorta like the Nobel committee, which is notorious for awarding A. Einstein with the prize for the photoelectric effect and not special or general relativity :P. I'm sure Nature will publish these guys a few years down the road after they have garnered enough of a reputation (IF they are correct that is!).
I was just trying to point out the decisions involved in publishing with Nature. If people want to publish something quickly that will spur interest and spawn more research in that particular area, they do NOT publish in Nature; rather they would publish in a more "everyday" journal like Biophys. A Nature publication (unless you research frogs; for some reason frogs are hot in NATURE =D) is sorta like a fine wine. You just can't afford to waste time on it everyday ;). Plus, its rather dishearten
IAAP (I am a physicist) and an electical current is the movement of electrical charge. Consequently your "electrochemical state changes that propagate along nerve axons" are in fact electrical currents in the strictest sense of the word. When we have moving charge we have a current end of discussion.
The fact the propagation speed is much lower than when the electrical charge is an electron and the medium is a metal is entirely irrelevant. Lots of mediums exist that propagate electical current at much slower speeds than metals. I would also point out that propagation speed of an electrical current bears no relation to the velocity of the charge carriers either.