decoding the human brain

F. Frank LeFever flefever at ix.netcom.com
Mon Mar 16 23:35:51 EST 1998


re Cheng's "authoritative" but uninformed answer: no, one would NOT
"sense an electric field" any more than one would "sense" a touch if
one's brain was touched (e.g. with a finger or a probe).  You should
have offered this as merely your (uniformed) hunch or guess as to what
would happen.

If strong enough and well enough localized, it might produce sensations
appropriate to the area stimulated, even if not appropriately coded or
modulated, as with well-known examples of direct electrical stimulation
(cf. Penfield for a very old example).  In other cases (cf. Ojemann's
more recent work) it might simply arrest or block a specific ongoing
local activity (e.g. interrupting a verbal response)--OR
"paradoxically" (I believe has some data re this) strengthening recall
of an item.

The hot item these days is MAGNETIC stimulation (yes, there is also an
excellent but under-utilized procedure for recording local magnetic
activity of the brain)--so far mostly restricted to stimlation of
mortor or somatosensory cortex, with predictable results (NOT "sensing
a magnetic field" but a motor response or a somatic senstion), but I
have heard recently of its producing overt laughter and a sense of
"everything is so funny" (possibly cingulate cortex?  don't
recall--heard it fleetingly, on the radio).

NYNG had one of the pioneers in this area (Cracco, I believe)
describing the technique at oone of our meetings many years ago...

Frank LeFever
New York Neuropsychology Group  (NYNG)




In <350D1607.4E50 at postoffice.idirect.com> K C Cheng
<kccheng at postoffice.idirect.com> writes: 
>
>Emmanuel Garcia wrote:
>> 
>> Is there research currently carried out in order to understand which
>> areas of the brain are involved when thinking about some specific
>> subject, and ultimately to be able to read one's thoughts by
translating
>> the electric potential field of the brain ?
>> 
>> I've heard about studies trying to locate rougly which areas of the
>> brain are involded when speaking, writing, thinking of images and
>> so on using such techniques as tomography. Are there equivalent
studies
>> trying to correlate the potential field on the surface of the head
>> with the kind of thoughts one is having ?
>> 
>> Is it possible to have a reverse approach, i.e. is it possible to
>> set a field of electric potential on the surface of the head (and
>> even inside using microwaves ??) and ask the subject what he/she is
>> thinking about ?
>> 
>> Thank you for giving these questions some attention and sorry
>> if I'm completely off-topic or if all this is nonsense, but I'm
>> still dreaming of a direct human/machine interface.
>> 
>> Emmanuel Garcia
>> garciae at poly.polytechnique.fr
>Just like the TV signals being the same in  field strength and
>wavelength and yet constantly carrying totally different contents,  or
>the nerve impulses from the same optic nerve carrying different visual
>messages,   brain surface electric potentials would not vary in a
>content-specific manner.  The same brain surface electric field would
>carry totally diverse information and therefore thoughts.  
>The reverse,  i.e. having an electric field atop a person's brain, 
>would allow him to sense the thoughts, if any, contained in this
surface
>electric field.   But, if no brainwave-frequency information,  or 
>thoughts,  are contained in that field,  the person would sense only
>some sort of an electric field, nothing else.
>Some relevant info at
>http://webhome.idirect.com/~kccheng
>-- 
>kccheng:¹¿Â÷÷÷÷÷¥»¼§




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