HELP: Electrical and neurological connection

Edwin R. Yeh ery2 at po.CWRU.Edu
Thu Mar 3 20:22:56 EST 1994


In a previous article, kyeoh at news.uta.edu (will think of something...) says:

>	Has there been any attempt to  interact human nerves to any
>electrical devices in medical history?  (Input from electrical
>devices to the sensory and motor nerves.)

Certainly. 

I suggest that you go to the library or access your favorite on-line
database (like Medline(TM)...) and search for the key words: functional 
electrical stimulation (FES) or functional neuromuscular stimulation (FNS).

Off my head, I recall there was actually a book by Hambrecht called just
that -- Functional Electrical Stimulation. And of course, if you look
up the names of any of the professors here in the Applied Neural Control
Laboratory (ANCL) at CWRU like Drs. Mortimer, Durand, Crago, Peckham..., 
you will see that's what they do...  

The use of FNS is to restore the motor function of a person who had 
neurological problems such as spinal cord injury. By functionally and
selectively activate appropriate motor nerves, the theory is that the
person should be able to restore the lost function (whether it is the
hand grasping of an object, or posturing, standing, or walking.) 

>	I was just wondering if it is possible to connect inputs to
>any human nerves leading to the human brain.  

Depending on what you mean by "connect inputs to any human nerves leading
to the human brain," since most "nerves" are already connected with the
brain. :-) The examples I mentioned earlier primarily involved the
efferent nerves (i.e. nerves traveling "away" from the nervous system.)
The efferent nerves may innervate important organs that may need additional
helps from the outside after a lesion or disease. That's where FES can
come to rescue. Applications may range from ambulatory assistance, 
respiratory assistance (by stimulating at the diaphram), gall-bladder
control, etc...

If you are talking about the afferent nerves (i.e. sensory nerves that
travel "toward" the nervous system as an "input" or "feedback") that's
a different ball game there. Since this involves individual perception
and interpretation (and mostly "pain"), less experiments have been
conducted. (It's difficult to design an animal experiment to study the
animal's "perception". Moreover, even if it's successful it's difficult
to transfer the knowledge for the human beings.) But I've heard some
researchers had done some works in the sensory area (MIT?). I haven't
been able to locate any references, but if you know, I'd like to know.

Of course, there are also pioneering works done in auditory and visual
prosthesis where intracortical electrode arrays are used to directly
stimulate the respective cortex. And patients have reported hearing
sounds and seeing "stars" as a result. But remember neurons and its axons
are tiny (in the micron range [1x10e-9 m]) and "selective" activation
is a BIG problem. Sure they can work but if one's head is banged hard
enough, who's to say one wouldn't hear sounds or see stars. :-) Got my
point?

Good luck.

Edwin
-- 
Edwin R. Yeh < ery2 at po.cwru.edu > | Research Interests      
Dept. of Biomedical Engineering   | + Direct Neural Control & Perception 
Case Western Reserve University   | + Non-invasive Neuronal Data Acquistion
Cleveland, OH 44106               | + Brain-Computer Interface  



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