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Using Magnets To Turn Off the Brain's Speech Center
An editor for the Telegraph, Roger Highfield, recently volunteered to allow a UK researcher to shut off the speech center of his brain with a high-powered magnetic pulse. Regular speech is controlled by a section of the brain called Broca's area. Once the precise location is determined in the subject, a magnetic pulse can temporarily disrupt speech without impairing other cognitive functions. The link contains a video in which you can watch Highfield stutter and twitch while attempting to recite a nursery rhyme. A later test shows that he's able to sing the rhyme without difficulty, since singing is controlled in a different part of the brain (as you may remember from Scott Adams' speech disorder). Researchers believe that the ability to stimulate or quell activity in specific areas of the brain may help in treating conditions like epilepsy and migraine headaches.
The notion that this pulse "turns-off" the targeted segment of the brain isn't correct. The pulse does NOT remove power from the brain or suppress neuronal firing. Instead, it disrupts coordinated firing of the neurons by inducing a spurious current in the neurons. Thus it is more like randomly applying a signal to the pins of a CPU than to cutting power or clipping pins.
I can't imagine that this pulse is very good for neuronal tissue in the short-term or long-term.
Two wrongs don't make a right, but three lefts do.
As long as the person is expecting their speech to be disturbed, and they can hear/feel the exact moment that the magnet is pulsing, the effect could be purely psychosomatic. They really need to test this on someone who's not expecting these effects. It may be ethically a bit strange, but it's the only true test.
There's actually a few different types of controls which are used experimentally. Here's what I can think of off the top of my head:
* use a sham coil that triggers the same sorts of clicking sound but doesn't actually stimulate anything
* more recently, a different type of sham coil has been developed which allows you to modify current directions on-the-fly, allowing you to create the sound/sensation of scalp stimulation, but causes minimal stimulation in the brain region (disclaimer: this coil was devised by people from the same lab as me)
* you can switch which side of the brain you're stimulating on, and if the subject isn't familiar with neuroanatomy they'll be none the wiser. About midway down this page there's a video of someone counting upwards, and it shows that even though there's a disruption when you stimulate Broca's area on the left side of the brain, no effect is observed when the symmetric area on the other side of the brain is stimulated.