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.'"

Comments

Raised eyebrows...

[BWJones]

As a neuroscientist who has a healthy respect for a little anarchy from time to time, I have to call shenanigans on this one. I'd love to kick down the doors on some fundamentally held beliefs (my dissertation did something close to that), but this had me laughing out loud.

I've recorded from nerve cells in the classical manner and run the parametrics on different ionic concentrations and it would take quite a solid argument backed up by data for me to displace any of the credibility built on the classic Hodgkin and Huxley work.

Re:Raised eyebrows...

[Anonymous Coward]

As another neuroscientist, I would urge you to keep an open mind. Perhaps they mean the frequency of events fall neatly into the sound frequency range: i routinely see 20-200 Hz E/IPSC at RT, and much higher in larger neurons at 37'C. You can get action potentials at up to 1000 Hz in auditory neurons.
If anything, try plugging in a speaker into your patch-clamp amplifier's audio port and see how it sounds (Back in the days I would directly convert the frequency and amplitude of the events in my voltage-clamp traces to raw PCM and play that out, and it sounded like some kind of a pothead techno mix tape, something you could definitely listen to and even enjoy.

Certainly, the movement of ions across the membranes is what drives most neurons (forgetting about the slower metabotropic communication, kinases, etc. for a second), but perhaps thinking of these in terms of frequencies would help non-math people appreciate the neuronal communication (the concept of a choir singing in a labyrinth is a lot easier to grasp for a layman than even the most basic HH multivariable d.-equation models).

Re:Raised eyebrows...

[Ceriel Nosforit]

IANAPhy, but I study EM fiercely.

Seems to me that when you said "in the strictest sense of the word" you put the word of the law above the math of the law. Since we're talking about a change in EM propagating through space we're dealing with AC rather than DC, and when dealing with AC we're dealing with the EM fields and not the charged particles mediating the fields. The EM fields of course move at c, and since the signals propagating through the nerves move a lot slower than that, we probably should conclude that AC isn't the mediator of the signals.

The EM fields are much, much stronger close to the charged particles in the neurons, and it is a chain-reaction caused by one charged particle in very close proximity to the next that propagates the signal. One could say that every link in the chain-reaction in the nerves is an amplifier that ensures that the signal is just as strong when it reaches its destination as it was when it was emitted. Were we talking about EM fields, the field strength and therefore the recoverable signal, would diminish at an extremely fast rate since water (which we're mostly composed of) is a very poor conductor of the magnetic field, and an isolator when completely pure. Even if the neurons did communicate with EM fields, we'd be rendered inoperable thanks to the very strong background radiation we're constantly exposed to.

In conclusion; neurons do not communicate with electrical currents, but with chemical reactions.

Re:Raised eyebrows...

[mrbluze]

The Meyer Overton Hypothesis specifically relates to volatile (inhaled) anaesthetic agents, and NOT morphine which clearly has a receptor based mechanism of action. It's not correct to use the hypothesis for drugs such as opioids, or barbiturates (eg: thiopentone/pentobarbital), for which a receptor based mechanism of action has been established.

So, no, it doesn't predict the potency of most drugs, just the inhaled ones whose potency is directly proportional to solubility in octanol or olive oil.

Might be mistaken...

[Nemus]

I am currently in an Intro to Neuroscience class atm, but this sounds a bit...off. I am, obviously, not a scientist, but it seems to me that 1.)neurons and their associated structures do not have the physiological equipment necessary to produce sound, and 2.)Considering that the vast majority of passive and active scanning procedures specifically monitor or stimulate electrical activity in the brain, this seems a wee bit kooky. But, as stated, I ain't a scientist. Sage wisdom, folks?

Re:TFA is completely innacurate

[myc]

BTW, IAANS (I am a neuroscientist). Here is another link to their earlier research on this. While PNAS is certainly a reputable journal, I made some interesting observations while reading their paper:

(1) It's very physics- and modeling-heavy. While I don't like to generalize, my impression has always been that physicists are not very good biologists. I've been to many a "cross-disciplinary" seminars where physicists try to model biological processes, and inevitably they make very little biological sense.

(2) They cite mostly old papers from the literature (1960s) that point out deficiencies in the Hudgkin-Huxley model (although it's true that the HH model of action potential propagation may have become dogmatic).

(3) It was published via track I in PNAS, wherein a Member of the National Academy of Sciences can directly accept the paper for publication, bypassing peer review. The purpose of this mechanism is so that controversial works have a chance to be published; historically, it has been used to dole out favors and/or to publish crackpot theories.

Ultimately, while what they are proposing is not as crazy as TFA makes it out to be, the paper sounds to me that they are trying to make a mountain out of a molehill. Neuroscientists today have a very detailed understanding of how axonal neurotransmission works. The authors claim that the solitons (sound waves) in their model explain how nerve propagation in myelinated axons can be much faster than in equivalent non-myelinated axons, but again, neuroscientists are fairly sure they understand myelination in the context of the HH model. Even if axons go through soliton mediated pulses on the membrane that are in phase with action potentials (which is what they claim to observe), I seriously doubt that it has any physiological relevance, since just about everything neurons can do can be explained by ion flux through channels.

Re:Uh.

[omeomi]

I'm so tired of hearing the press use "scientists say" as a legitimizing opener.

Next up? "Scientists say light bulbs use sound, not electricity"

If you believe something because "scientists" say so, you are probably not a scientist

You're probably a politician...assuming the scientists in question are ones who work for the people who give you money...

Re:So when a tazer hits you

[Tatarize]

Well if you coat yourself with a conductive material, you would become in theory a sphere and thus have no electricity on the inside of the sphere. Not sure how much weaving and conductive stuff it would take to mostly negate the effect, but it could be done if it was done completely. Though if you make a capacitor vest and shock the bastard back... that'd be cooler and less practical.