Keeping Balance with Vibrating Shoes

DrLudicrous writes "The NYTimes (free registration) is running an article that summerizes a forthcoming Physical Review Letters article. The article is about how low amplitude vibrations can help a person better sense when they are off balance. The authors write that they improved the balance of senior citizens by using small vibrations in the floor, making their sense of balance like that of a 25 year old. Apparently, this background noise helps to stimulate the neurons in the feet, making them more susceptible to detecting imbalances."

Control of balance?

[autocracy]

I was under the impression balance was primarily controlled by the inner ear... how much of an effect do your feet really have with this?

imagine

[Anonymous Coward]

i should be able to balance really well during an earthquake.

Fix their vision too!

[someguy]

Current research is showing that a lot of the problems with the elderly and having accidents - vehicular or otherwise - is strongly correlated with attentional problems that they have. Their functional field of view [google.com] suffers and, combined with other things is responsible for a lot of their problems.

So, while this vibrational shoe may have some balance effects, it's only part of the problem that they're fixing.

Balance Vs. thresholds

[girl_geek_antinomy]

This was in New Scientist a fortnight ago (and that on -publication- date)! What a slow pick-up... :)

Seems it has to be random movement noise because any signal which is both repetitive and apparently irrelevant gets 'ignored' pretty quickly by the brain - after all, there's all kinds of signals coming through all the time like the feeling of your socks on your feet that you're not consciously aware of (though bet you are now, eh?).

Also, it's not really about balance (which, people are right, is sited in the middle ear primarily) and more to do with thresholds for detection - having random movement / vibration happening anyway means that the body swaying off-balance is likely in one phase to be reinforced by the vibration enough that it goes above threshold and the body realises that there's uneven pressure in the feet and corrects it - neat, no?

Has anyone else heard about the research into people balancing sticks on their fingertips, and how this has to do with random neuro-muscular noise, but generated by the body instead?

Re:Possible use for MS patients?

[girl_geek_antinomy]

It's possible, though the nervous problems MS suffers experience are different to those seen in old people. It's likely that something that makes it more likely for an off-balance signal to go above threshold in a normal patient is unlikely to do any harm in MS though.

Diseases like Parkinson's and Huntingdon's may well be more complicated, though, since they're caused not by problems in the periperhal nervous system but by breakdowns in the systems in the brain that control movment.

Re:Fix their vision too!

[girl_geek_antinomy]

If you read articles related to this research, it seems that what's happening here is a physical threshold effect in individual collections of peripheral neurons rather than anything happening primarily in the brain (in any case, balance control only very very rarely goes conscious - that moment, when you think 'shit, I'm going to fall over and pour this latte across the floor!') The stuff on attention is really interesting, though.

Re:Balance Vs. thresholds

[ElJefe]

Has anyone else heard about the research into people balancing sticks on their fingertips, and how this has to do with random neuro-muscular noise, but generated by the body instead?

I'm not sure if this is what you mean, but it's possible to stabilize a pendulum (e.g., a stick) in an inverted position by vibrating the base (e.g., your hand) rapidly. Here's the first link that I could find on Google. [bris.ac.uk] It's been a while since I've dealt with the math, but I think it has something to do with the Mathieu equation [wolfram.com] from Floquet Theory [wolfram.com].
</math lesson>

stochastic resonance

[sanermind]

It isn't the vibrational energy that is stimulating the neurons in the feet. Instead it's the additional quantity of information (that can be conveyed to the brain along aging pathways), by mixing in some noise. It may sound counterintuitive that noise can increase the resolution of a signal, but it makes sense. Imagine a signal is quantized in steps, and a sample could possibly fall between the discretely measurable points of sensitivity, and get lost. By adding noise enough to 'blur' the sample into a range that will always cross one sample boundary, then it will be detected more frequently. Even if it's blurred to cross two or three at a time, the relative activation of the seperate 'sensor nodes' allows an accurate determination of the actual quantity being sampled [given that the sampling resolution sufficiently exceeds the time resolution of changes in the actual value being sampled].
It's called stochastic ressonance.
It's used in some analog to digital converters, and in many other places in engineering, it's been used in electron microscopes, in radio telescopes.
And now, it turns out, it looks like it's used in people! What is really interesting is the question of whether or not the healthy adult body actually has automatic noise generators itself, for precisely this purpose, which may have weakened in the case of the elderly.

Re:Control of balance?

[Dog and Pony]

Yes, that is true. However, having a slightly unsteady surface (ie vibrating) to walk on "keeps you on your toes", so to speak.

And that is how this works. On normal, solid and stable ground, the balance system "gets lazy", but by providing subtle shifts in the "ground", you force the balance system to so to speak, concentrate on what it is doing.