On Thu, 5 Jun 2003 13:48:18 +0000 (UTC), dan{at}oricomtech.com (dan
michaels) wrote:

>r norman  wrote in message
news:...
>> On Tue, 3 Jun 2003 13:54:00 +0000 (UTC), dan{at}oricomtech.com (dan
>> michaels) wrote:
>> 
>................
>> >This is all kind of jumbled, but I am trying to think of how the
>> >temporal aspects of the brain evolved, and am thinking it must have
>> >been more connected to the movement side of the organism, and not to
>> >the sensory side. 
>........................
>
>> I think you are off on a side track taking you nowhere.  
>> 
>> Clearly, temporal sequencing of motor activity is necessary to produce
>> any patterned activity.  This in seen in all the rhythmic activities
>> of locomotion: swimming, walking, flying; in respiration: breathing
>> and ventilation of gills; in digestion: GI motility, peristalsis. But
>> temporal analysis of sensory activity is just as necessary to detect
>> motion, to localize stimulus source, to differentiate novelty from
>> constancy.  You are asking "chicken vs egg" questions
about which came
>> first.  Nervous systems have the ability to do both spatial and
>> temporal processing.  
>
>
>RS, thanks for your input. It has been very helpful. Yes, it is a
>chicken vs egg problem, and yes, once you get up to the level of
>mammals the brains have developed to the point where significant
>temporal processing takes place on the sensory side of things.
>
>But I was thinking that, lower down the chain where everything began,
>one might make the case that some kind of central movement mechanisms
>[ie, temporal] exist where very little central representation on the
>sensory side exists. Nicholas Humphrey in History of the Mind makes
>this case about earthworms. Bascially, punctate sensory input can
>elicit a temporal chain of movement effects, with very little temporal
>processing of sensory inputs taking place at all in the animal.
>
>Now, if one believes that nature over and over re-used the previous to
>evolve the successive, then one might surmise that the later-evolved
>brains organized around a temporal paradigm of processing. Just a wild
>surmise, and over-generalization on my part, I suppose.
>
>
>thanks, mucho grande,
>- dan michaels
>===================================

Again I want to emphasize that temporal processing of sensory
information is very old, far older than mammals or vertebrate animals.
It is part and parcel of the way nervous systems work.  You can NOT
separate out temporal processing from spatial processing when you
discuss synaptic integrative mechanisms -- they are both there and
have been since the beginning.

Flying insects respond to very rapidly changing events.  They have to
detect direction of motion.  It is very important to know that this
event occured before that one.  Imagine the problem dragonflies have
capturing prey on the wing. Many insects respond to calls -- the
temporal feature of a cricket chirp is an essential part of its
signalling.  Different crickets have different patterns.  Fireflies
signal reproductive behavior by flashing.  Different fireflies have
different temporal patterns of flashing.  I referred to the common
distinction in sensory systems, vertebrate and invertebrate, between
phasic and tonic receptors. That separation is clearly part of
temporal information processing.

Whatever Humphrey may say about earthworms, it is simply not true that
you can "surmise that the later-evolved brains organized around a
temporal paradigm of processing". Even with earthworms, I don't think
that the statement is true.  Clearly they locomote with waves of
contraction moving down their bodies so the motor system does require
temporal processing but you fail to recognize that motor and sensory
systems are intimately integrated.  All animals have systems of
proprioceptors that detect body position or movement and these
feedback to the motor system to regulate, control, and coordinate the
movements.  Certainly these parts of the sensory apparatus are
involved in temporal processing!
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