genetic control of inter-neuron signals

Sandy Hodges QXUXBTVOTSAO at spammotel.com
Tue Apr 13 15:41:41 EST 2004


QXUXBTVOTSAO at spammotel.com (Sandy Hodges) wrote in message news:<32a9f965.0404011132.30a4d943 at posting.google.com>...

> Few people desire sex with a sibling.    ...  
>    Thus from the neuron's point of view, it
> does not "know" that it is recognizing your sister.   It only knows
> that it responds to the neurons that connect with it - it has no way
> of knowing what those other neurons are.
> 
>    ...  Sandy Hodges

SH: Many interesting responses - sorry to be so slow in getting back
to them:

    Glen M. Sizemore (gmsizemore2 at yahoo.com) :

Then why do cultures spend so much on enforcing incest taboos? They
don't, after all, produce taboos against eating feces, despite the
fact that eating feces is frequently bad.

    SH:
well, they don't actually.  What they spend time on is extending the
incest taboo to people who are not in fact one's siblings, but who are
defined culturally to be so, such as members of one's clan.   
Incidence of incest between siblings raised together is very low.  I
don't know about the incidence of eating feces, but I've heard that it
does happen.

    NMF (nm_fournier at ns.sympatico.ca):

It seems to me at least, that these original studies lost a lot of
magnitude after Bliss and Lomo work in the 70's showing that the
Hebbian concept of long term potentiation was operating within the
hippocampus and could be a correlate of learning (after the influence
of Lynch and Baudry).

   SH:

My main hope is to convince people that the Hebbinan paradigm does not
provide an explanation (and essentially rules out the possibility of
an explanation at the molecular level) of the genetic control of
behavior, which we know exists.   Note that I do not propose that
information is exchanged chemically in the process of acting thinking
- it would be an influence on long term potentiation only - some cells
that fire together would not after all wire together.

    r norman (rsn_ at _comcast.net) :

Second, if the protein did enter the cell, there is the decoding
machinery to deal with.  For now, the only known way a complex message
like you envision could be decoded is for it to bind to a specific DNA
sequence and so activate a specific gene.  ... Third, nothing we now
know about the genome or the processes of protein/DNA interaction
suggest that information could be transmitted the way you suggest. 
Even if genes could be activated, there are only so many ways a cell
could react by changing its activity.

   SH:

Here is the mechanism I have in mind (again, my only goal is to
suggest a possible mechanism).  I think my mechanism answers the
objections "only known way a ... message ... COULD be decoded" and
"nothing we know ... suggests ... information COULD be transmitted."

The gene for controlling the behavior has two binding sites, and it
encodes for a short tag. Call one site the "sibling" site and the
other the "sexual arousal" site.  Call the tag the "refuse synapse"
tag.   There are a great many genetically controlled behaviors, so the
gene for any one behavior does not encode any mechanism - the
mechanisms are encoded by genes that work for all the behaviors.

Let us say the neuron has worked out (by a means I'll get to later)
that it is a neuron that becomes activated when seeing a sibling.  
This means, by my proposal, that a stretch of RNA that only occurs in
such neurons, circulates in the cell.   It binds to the "sibling"
binding site on (RNA copies of) the behavior gene.

There is a receptor at the synapse.  The receptor takes in a specific
peptide, and it makes a one-to-one transcript of a stretch of that
peptide, to an RNA tag.  All that is required, is that the tag which
the receptor releases into the cell, depends in some way on the
structure of the peptide, in such a way that a virtually unlimited
number of distinct possible peptides, each result in a distinct tag.

A "sexual arousal" neuron releases at the synapse, into inter-cellular
space,  a peptide which is unique to such neurons.   The receptor on
the post-synaptic neuron takes in this peptide, and produces a unique
tag. The "sexual arousal" binding site has evolved to recognize this
tag.

Now the behavior gene has both binding sites filled, and is activated,
and the "refuse synapse" tag is circulated.   Other genes are such
that proteins needed for consolidating the synapse, are deactivated by
this tag.

But how does a neuron know that it is a "seeing a sibling" neuron?   
Well, suppose the neuron has already worked out, early in development,
that it is a "face recognition" neuron.  Genes activated only in such
neurons, are activated.    Other genes are activated only when the
individual is under five years old.   Then all the neuron has to do,
is respond to how often it becomes excited.   If the neuron is excited
several times a day, while the individual is under five years old, and
if the neuron is a "face recognition" neuron, then the neuron can
activate the genes for being a "seing a sibling" neuron.

The "sexual arousal" neuron is connected, perhaps through other
neurons, to cells that produce sex hormones.   Only by exchanging
complex chemical signals (that is, I don't see any other way to do
it), can a Hebbian neuron learn that it is connected with sexual
arousal - and only thus can genes to influence sexual behavior, know
when to work.

- Sandy Hodges



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