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

john f andrews ece jfa0522 at hertz.njit.edu
Mon Aug 5 08:40:13 EST 1991


To: tbd at neuro.duke.edu
Subject: okay, I'll bite: Magnetic Cortical Stimulation 
Newsgroups: bionet.neuroscience
In-Reply-To: <22610 at duke.cs.duke.edu>
Organization: New Jersey Institute of Technology, Newark, N.J.
Cc: 
Bcc: 

In article <22610 at duke.cs.duke.edu> you write:
>In article <1991Aug2.180631.1 at hmcvax.claremont.edu> jvargas at hmcvax.claremont.edu writes:
>>Hello.
>>
>>There was nothing in here so I thought I'd write something so that this file
>>doesn't feel lonely.
>>
>>					Idiot-Without-A-Clue
>

I have become involved in an experimental project involving transcranial
magnetic stimulation of the motor cortex.

Naturally, this is a frontier area, and is not well understood as of yet. 
Has anyone any information regarding this?

FYI, a high-field (2T) biphasic
magnetic pulse is sent through a coil which has been postioned on the scalp,
over the motor cortex. The coil design is such that the field gradient
is high, with a theoretical field focal point a few centimeters beneath
the scalp. The focal "point" is less than a square cm, and may be 
even sharper (depending on your definition of focus, the threshold for
stimulation, and the true-ness of the theoretical field mapping).
It is supposed that the field is at the very least concentrated within
a cortical column.

The changing field induces an electric current in the cortex, regional to the
field gradient at pulse time. In theory then, this is electrical stim without
the need to burn a path from the scalp down to the area of the cortex to be
stimulated. The current densities are comparable to those recorded with 
selectrical stimulation. The effects are also similar, i.e. motor response
elicited through selective cortical stimulation.

Is it "safe"? Is it useful? It is (is it?) non-invasive... 

It has been around a few years, there are a few companies building stimulators,
it has FDA approval for peripheral stimulation, and several researchers have
been doing transcranial stuff for a few years (mainly NIH researchers).

							-=john


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john f andrews                SYSOP           The Biomedical Engineering BBS
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john f andrews                SYSOP           The Biomedical Engineering BBS
    24 hrs             300/1200/2400/4800               (201) 596-5679
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