okay, I'll bite. Anyone for Mag Stim?

john f andrews ece jfa0522 at hertz.njit.edu
Tue Aug 6 12:56:16 EST 1991

In article <1991Aug6.021131.25339 at agate.berkeley.edu> neveu at milo.berkeley.edu (Charles Neveu) writes:
>In article <1991Aug5.134013.19105 at njitgw.njit.edu> jfa0522 at hertz.njit.edu (john f andrews ece) writes:
>>Is it "safe"? Is it useful? It is (is it?) non-invasive... 
>I've been a subject for a magstim experiment here at Berkeley.
>Hopefully it's safe. It's non-invasive in that it doesn't require
>brain surgery, but when you pump enough current through a coil to get
>the kind of magnetic fields required, the coil compresses and expands
>(it's an electromagnet) with such rapidity and violence that it's like
>having someone fire a .22 next to your skull. Also, it stimulates the
>muscles of your scalp, so there is an unpleasant twitching in your
>head and neck.  In the experiment I was in the experimenters were
>trying to stimulate the visual cortex to produce phosphenes. They were
>very faint, but definitely there (they didn't do the control
>experiment, which would have been to fire a .22 next to my skull to
>see if I still saw phosphenes...).
>Charles Neveu
>Neurology Unit
>U.C. Berkeley 

The noise if caused by the fine magnet wire snapping against the epoxy 
housing of the coil/wand. Ours is not too loud... actually it's soft.

As I mentioned in my reply, I am surprised to hear of scalp stimulation,
as the theory says there should be no stimulation in the plane of the coil.
Perhaps a bit since the coil is not perfectl flat? Hmmm...

There has been talk of a concern over epileptic kindling, although
recently talk is that it doesn't seem to be happening (Dhuna 1991).

I am curious if anyone else is experimenting with mag stim, or has any 
experiences with it to relay....


john f andrews                SYSOP           The Biomedical Engineering BBS
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