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FSK, Vision, and the Brain

r norman rsnorman_ at _comcast.net
Sat May 10 17:42:34 EST 2003

On 10 May 2003 13:35:35 -0700, peer-error at excite.com (External Network
Error) wrote:

>r norman <rsnorman_ at _comcast.net> wrote in message news:<cqqpbvgsktmgosm9sad08spq7l868a7929 at 4ax.com>...
>> On 9 May 2003 20:05:58 -0700, peer-error at excite.com (External Network
>> Error) wrote:
>> >Hi:
>> >
>> >I am planning on developing a digital/brain interface. It uses FSK
>> >[Frequency Shift Keying] signals. It is in a silicon-chip. This
>> >silicon-chip is attached  to a subject's visual cortex [chip's
>> >circuits connected to visual cortex's neurons]. The chip processes
>> >FSK. The chip has information about the subject's visual cortex. In
>> >order to produce the correct visual perception, it has to:
>> >
>> >1. Convert to FSK information to a language the visual cortex can
>> >understand
>> >2. Excite the correct region[s] of the visual cortex with the
>> >compatible language.
>> >
>> >My design acts by affecting negative neuronal ions in the visual
>> >cortex with electrons. The digital electric signal is initially
>> >FSK-modulated. This signal's format is then altered so that it can
>> >communicate effectively with the visual cortex [by affecting its
>> >neuron's negative ions].
>> >
>> >Any hints accepted.
>> >Thanks,
>> >
>> You don't indicate what degree of knowledge or experience you have
>> with neurophysiology.  But from the way the proposal is stated, I
>> suggest that you start with a laboratory course in neurobiology.  You
>> need to understand "the language the visual cortex can understand",
>> exactly what the role of "negative neuronal ions" (chloride?) really
>> is, and just how your electrons can exert an effect.  It really is not
>> clear why you emphasize FSK (frequency shift keying).  Frankly, it
>> makes absolutely no different to the brain what the internal
>> representation your digital circuitry uses -- a system using Cobol and
>> binary coded decimal numbers should work as effectively as anything
>> else, provided the design is proper.
>> Note: the laboratory nature of the course is essential.  You have to
>> understand just what is involved in the reality of neurophysiology.
>> After that, go into a graduate program in neurobiology or
>> bioengineering or whatever in some institution that is involved in
>> visual prosthesis and get attached to a research group as a grad
>> research assistant.  Then, after some post-doc work in the field, you
>> will really be in a position to put your ideas (which might change
>> just a tad from the experience) to real use.
>There is a electronic brain device currently used by the blind.
>Electrode stimulate the brain to produce visual perception. A major
>disadvanted is the heat [generated by electrons flowing against
>resistance] damage brain tissue eventually rendering this technique
>useless. Burnt tissue is dead and does not respond to excitation of
>any type. I am thinking of a device using electrical stimulation w/out
>generating a denaturing amount of heat.

Again, I must repeat my advice -- take a good neurophysiology lab
course. In an intro course, you may not learn the details about how
electrodes actually work, but you certainly will if you do any
"advanced" work -- i.e. a good senior or graduate level course.  Learn
about polarizable and non-polarizable electrodes and how they actually
interface with neural tissue.

Basically, anything that produces an electrical potential in a
conductor will produce a corresponding current which will dissipate
energy (simple Ohm's law).  You can't get around it.  There are
techniques to minimize the resistance in the electrode and at the
electrode-tissue interface which reduces the amount of heating.
However, in order to stimulate a very small number of cells (and thus
in order to produce a very specific and specialized response), your
electrode must be very small.  Small electrodes have high resistance
-- a simple law of physics.

Also, the electrode can react mechanically and chemically with the
tissue to produce cell damage and death.  I frankly would suspect that
the heating would be a minimal aspect of long-term neural damage with
electrode implantation.  However, I may be wrong about that.  In any
event, the people you cite doing the neural visual prosthesis work are
quite well aware of all of this.  The prosthetic electrodes being
used, especially any electrodes being used for chronic implantation in
humans, are carefully engineered to produce the least harm possible
with today's knowledge and engineering skill.  Why would you think you
could do better?

To be quite honest, you may indeed have the intelligence, imagination,
and creativity to beat current technology.  However you still have to
learn all the details of current technology before you can convince
people that you can improve on it.  Also, the way the game works is
that you have to learn to be a player before you can participate. 

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