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MRI Magnets Cause Nystagmus
Hitting the main page for the first time, tibit writes "In an interesting twist on 'it's so old it's new again,' Johns Hopkins researchers led by Dale Roberts found what must have been causing much confusion for doctors the world over: strong external magnetic fields can stimulate the semicircular canals, causing vertigo and nystagmus (pendular eye motion). It's a textbook case of the Lorentz force in action: our angular rate gyros, the semicircular canals in the middle ear, filled with endolymph, have a ionic current flowing across. In a magnetic field, the current produces a force that pushes the lymph along the channel, causing stimulation of the cupula — a pressure sensor at the end of the channel. This is interpreted by the brain as rotation of the head in space, and causes a nystagmus that's supposed to stabilize the image on the retina. Of course, the subject is laying down and not spinning in space, and the mismatch between inertial measurements coming from the ear and the real situation causes vertigo."
We have MRIs at work, I get that Just-Stepped-Off-A-Roller-Coaster dizziness when moving through the field, the effect is well known.
Old news or am I missing something?
Trolling is a art,
Fucking magnets - how do they work?
The rapid eye movement, looking from side to side, peeking under things, etc. while out geocaching near guardrails.
A feeling of having made the same mistake before: Deja Foobar
I did this just the other day! It's actually a bit scary because if you are just working with the magnets (and not a subject), then it only happens with high field systems. You know, the ones that can accelerate a forgotten pen or a paper clip into a lethal weapon. And it happens just when you're leaning your head over the entrance to the magnet, making an adjustment, and likely to be doing something stupid. It was scary the first time it happened to me, and it still gives me serious pause when I approach the barrel.
Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
Congratulations, you know absolutely nothing about cancer or biology in general.
This is a classical example of how you just have to take the time to read the paper and think about it because the cited text and other sources that are not behind pay-wall are just not clear enough.
I have had put my head in number of MR scanners, with field strengths of 0.3T, 0.5T, 1T, 1.5T, 2T, 3T, and 7T, with no nistagmus, but that simply does not mean anything in context of this paper.
You should have in mind that the maximum magnetic field gradients, and their speed are regulated by law.
Interesting question that this paper is offering: are functional-MRI results sometimes tainted by effects of magnetic field gradient while the person is placed inside the device?
Doing a good job is like spilling coffee on a dark suit, you feel warm all over, but nobody notices.
...to explain the eye rolling when people read the bill for the MRI.
Forget magnets....
Fucking cancer, how does it work?
On what magnetic fields? MRI fields are _tremendous_, you won't be able to sense anything with simple hand-held magnets, even with the rare-earth ones.
You're fucking stupid and you can't type, either (equably, lol).
Biologists and engineers know that sufficiently large magnetic fields can affect living tissue. There are YouTube videos of living frogs levitating inside a 10T bore.
Biologists and engineers ALSO acknowledge that RF has an effect on living tissue. This effect is otherwise known as "heat".
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It's telling you use the bullshit argument of not knowing "precisely" where sensitivity ends when we're talking about effects that are orders of magnitude apart.
Of course I'll happily change my tune when someone can demonstrate a measurable effect on the body from a magnetic bracelet (why not headbands since it's the brain that is known to be affected?), or sensitivity to a Wi-fi router or cell phone tower in a double-blind study. So far such studies have shown no effect, ergo its bullshit.
But you're right -- surely not everyone is equally sensitive. Maybe by some coincidence everyone who thinks they're more sensitive turns actually turns out to be less sensitive!
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A quick note to tibit, the submitter, to say nice summary. No hyperbole, no outrageous barely marginable links to another agenda, a suggestion, mechanism and evidence. I really enjoyed it, a bit of my brain went "Really? Oh? Like that? Oh that's quite clever, I see what happened there."
You know, it actually makes me want to go and read the article. I think I will. Nice one. More weirdly interesting stuff like this please. Off-topic in many ways, sorry. If it makes up for it, I learned to look for nystagmus when working as a bartender. There's a fairly strong correlation between BAC and the degree of nystagmus in a drunk person as they follow an object with their eyes. You can use this to judge how drunk a person is fairly accurately. In the "controlled circumstances" of me asking off-duty colleagues and friends to follow a finger for ten seconds I could usually work out how much they'd had to drink to the nearest 10ml of alcohol (1/2 pint or a shot of whisky in the UK).
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Do not close your eyes, and keep plenty of illumination (the more the better). This can at least inhibit the nystagmus to some extent. So at least you won't lose your visual acuity. The extra scary part, when talking about paperclips and such small things, is that inappropriate nystagmus (such as in a large magnetic field) causes you to lose visual sensitivity to high spatial frequencies, and paradoxically increases sensitivity to low spatial frequencies. You stop seeing small stuff, and you can remain unaware of it. The brain will, for a while, substitute made-up stuff to match your expectations. This is what gets fighter pilots killed: they get G-force induced nystagmus, lose acuity needed to read the instruments, and their brain is substituting expected (but incorrect) values for real instrument readings...
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Well, even on Slashdot, we can find a recent discussion of how magnetic fields affect the body, specifically blood viscosity in this case:
http://science.slashdot.org/story/11/06/02/185234/Researcher-Claims-Magnets-Can-Affect-Blood-Viscosity