Richard Norman <rnorman at umich.edu> wrote
> Dag Stenberg has already provided some information about the different
> types of synaptic transmitter that may be involved at a synapse. But your
> question has some unusual aspects to it. Just what do you mean by "higher
> frequencies" used to "distinguish one molecule from another"? I think
there
> is
> some pseudo-science stuff going around about "frequencies" involved in
> brain function that are somehow associated with brain chemistry and
> function.
>> The type of synaptic transmitter, and the significance of the transmitter
to
> the post-synaptic cell, has nothing to do with any mysterious "frequency"
of
> some signal. Depolarization of the pre-synaptic terminal triggers a chain
> of events resulting in release of transmitter. It is possible that
> different
> durations of depolarization or recent history of firing can influence the
> specific mix of transmitter in those cells that release more than one
> transmitter. And it is also true that chemicals differ in specific
> biophysical
> properties in which "frequencies" are involved -- like NMR or IR spectrum,
> but that is an entirely different concept. Just what do you have in mind
> when you ask about "frequency"
For many purposes, instrumentation can treat one impulse as
indistinguishable from another. They're both versions of the
theoretically perfect Dirac impulse. But to understand the variations
in what makes one impulse different from another, you have to look
at small differences among them. You mentioned pulse width as one,
but there are infinitely many frequencies in a real, imperfect, impulse.
For example, the incoming pulses from one set of dendrites may
cause a slightly different response than another set of dendrites. The
timing of incoming pulses can sum, or interfere, in different ways. So
its not just a question of whether the output impulse is there, but
what characteristics that impulse has, which might convey information
about how the impulse was generated in the first place.
Secondly, there is no reason to assume that the NTs crossing
the synaptic gap all have the same conformation. Yet identifying
possibly varying conformations is difficult, perhaps impossible
at this point in technology, since the conformation can change
as you measure it. That leaves the electrical signature of one
impulse versus another as the most likely way to distinguish
messages, assuming that they exist at all. Although the NTs
may be stored up for hours before an impulse is generated,
conformation might change as charge distributions change.
Also, the DNA/RNA bases might carry different charges
that are more dynamic, reflecting message content. Or
maybe not; its just a thought worth looking into.
So I'm not suggesting very high frequencies for some mystical
reason, but as a way of distinguishing among very subtle differences
in the impulses as a way to shed further light on whether the
impulses themselves convey messages other than the simple
event of an impulse occurrence.
Has anyone seen any research reports similar to the quadrature
vision stimuli? That has stuck out as support for the message
hypothesis, though I haven't seen related research of any kind.
Rich