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Axon collaterals ?

k p Collins kpaulc at [----------]earthlink.net
Mon Jan 5 04:36:03 EST 2004


"r norman" <rsn_ at _comcast.net> wrote in message
news:kudhvvg74e3j8qa1uvli0nnnm18co052q0 at 4ax.com...
> On Mon, 05 Jan 2004 00:02:03 GMT, Matthew Kirkcaldie
> <Matthew.Kirkcaldie at removethis.newcastle.edu.au> wrote:
>
> >In article <hvn9vv0ljsu5b4c2vmcro9rnjvltojrfst at 4ax.com>,
> > r norman <rsn_ at _comcast.net> wrote:
> >
> >> On Fri, 02 Jan 2004 12:17:46 +1100, Matthew Kirkcaldie
> >> <Matthew.Kirkcaldie at removethis.newcastle.edu.au> wrote:
> >>
> >> >In article <erk3uvs9tqjkgkg2fklq2o4fls4u05ne2s at 4ax.com>,
> >> > r norman <rsn_ at _comcast.net> wrote:
> >> >
> >> >> Yes.  Even glutamate has both in the retina.  I misspoke
> >> >> about "all" the known glutamate receptors.  Glutamate is
> >> >> "ordinarily" excitatory in the CNS.
> >> >
> >> >What's the inhibitory glutamate receptor in the retina?
> >> >
> >> >While we're on the subject, it's worth remembering that GABA is
> >> >excitatory in the immature CNS.
> >> >
> >>
> >> The synapse from receptor to bipolar is supposed to be glutamatergic,
> >> even though "on" and "off" bipolars have opposite responses.  Here is
> >> a reference
> >
> >...
> >[skip many]
> >
> >Thank you!  Sigh, more reading.
> >
> >For others following the discussion, the other incredible thing in the
> >retina is that signalling is done by switching OFF the stream of
> >transmitter coming from the rods and the cones.  So a detectable burst
> >of light produces a temporary stop in the outflow of glutamate, and this
> >pause in secretion is what we actually detect as the basis for visual
> >stimuli!
> >
> >Show you how quickly the glial cells scavenge the glutamate from the
> >cleft - and why vision is actually the slowest of the senses in terms of
> >the briefest detectable stimulus.
> >
>
> It is a good example of the fact that a "negative" signal is just as
> good as a "positive" one in communicating information. Stopping doing
> something or turning something off is just as important as starting or
> turning something on.

Yes. And the ideal is a minimal positive signal, which is
maximally a 'negative' signal. "It's not this, that... "

It 'is' what's left when as  much as can be 'negated' is 'negated'.

Via successive-approximations, with both positive and negative
feedback, ad infinitum -> the TD E/I-minimization mechanisms
'blindly'-automated 'crunching' -> convergence.

Hypothesis ["(?)"] with respect to the always-mostly-on-ness
of outputs from the photoreceptors:

The mostly-on-ness acts as a gross-TD E/I-minimization
mechanism - inhibiting 'everything', unless the retinal outputs
are switched-off(?)

This'd be robustly-useful with respect to supersystem-
integration via TD E/I-minimization, be-cause, when
disinhibition occurred, it'd automatically trigger active
TD E/I-minimization and, importantly, "supersystem
reconfiguration" [AoK, Ap5] with specific respect to
the 'released' activation, and, with such, tuning of
attention, including front-center orientation [also in
AoK, Ap5]. [The disinhibition is 'ideal' because it
results in a 'raw-material set' that can be "whittled"
via abstract TD E/I-minimization.]

When one closes one's eyes, 'everything' is inhibited,
and, via the widely-'correlated' TD E/I-minimization,
this enters into the onset of sleep-consciousness'
huge "supersystem reconfiguration"(?)

This'd work splendidly.

[I purchased an up-to-date text about a month ago,
but have not gotten around to studying it yet. I did
check the 'always-mostly-on-ness', though. The rest,
I'm just 'winging' on the basis of what's been in AoK
all along.]

ken [k. p. collins]








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