Re: exhaustive definition in the life sciences - an oxymoron?


feedbackdroids wrote:
>Both pathways are part of the cerebral cortex, which I guess is
>specific to mammals. And the specialization into more and more visual
>regions probably progresses as you go up the mammalian chain. Eg, mice
>and rodents probably have fewer visual areas by a bit, and humans more.
>I imagine the ventral pathway is highly developed in rodents, but
>cannot cite specifics. Going back to reptiles, they don't have a
>neocortex, but certain frontal areas which are are considered to be
>protocortex. Such lower animals have the superior colliculus [or optic
>tectum] as their major visual area, and this still exists in humans as
>a 3rd central visual pathway, but it has largely been overtaken by the
>cortex. People with damaged visual cortex can still "see", but not
>"consciously see" ... eg have something called "blindsight". This is
>probably similar to what the pre-mammalian species have.

consciously seeing suggests to me that some reasoning
is involved, (the signals are re-routed and combined,in
the act of thinking) but does this mean that same signals
of'blindsight'just dissipate?, a frog will only act if its
prey is moving, is this an example of blindsight? perception
of a static field of vision require other reminders to
bring the object into conscious reality?. Over 50ft we
can't tell if a static scene is actual or 3d (danger at
50ft away probably gives us enough time to leg it if an'it'
gets any closer).I was about to ask about blindsight and
difficulties navigating around obstacles in the immediate
path, but the added dimension needed about depth might be
provided by head movements (focusing feedback etc).
I'll look into it.

I looked up Liz Spelke;
http://homepage.mac.com/ddobbs/DDNewPage/page6/LizSpelkeandInfantCognition.html
'So began Spelke's career of pondering big questions with
little experiments on tiny people. This mixed-modality
binding experiment addressed the same question that
Locke's blind-man problem did, which is also essentially
the "binding problem" that remains a puzzle at the
neurological level: that is, how does the brain mesh
the signals from different senses into a single
impression? Spelke didn't answer the question
about how. But she showed decisively that this ability
lies in capacities seemingly innate.'

I can't help thinking that the impressions of objects
within our local vicinity have a temperal dependance,
for instance, we are only fully aware of them for the
time we are consciously focused upon them. Memory
retention & retrieval seem to require the object is
linked to an event or environment, if I'm honest its
quite difficult to recall objects in isolation.

So I'd design data storage with a time stamp - sort of;
12:15=blue/cube/2mtres/humming/latex smell/smooth terrain
12:16=blue/cube/1mtres/humming/latex smell/smooth terrain
12:17=blue/cube/contact/explosion/burning smell/rough terrain
12:18=black/plane/contact/no sound/smoke smell/no floor
(roughly translated'I was heading towards the box,
tripped over it and everything went black')

maybe include a search engine for a key word search to bring
up the time/data events....kinda get it to act like a
memory retrieval system. Hmmm, tho how to get a machine
to learn how to use a search engine on its own is a
different matter of course :) - It can't be impossible,
but once thats done - maybe it might even be possible
to develop a machine with the independant capability to
self generate the imaginary ? Hell of a lot of data though.
Isn't there a way to collapse the identical parts in different
files?

>One thing about the jumping spider visual system, if you think about
>it, is that can extract a lot of useful info without having to bring
>massive amounts of processing power to bear. There is a slit-retina
>[ie, only a 1-D line of N photoreceptors, rather than 2-D array and N^2
>receptors], and this is scanned back + forth over time. So, relatively
>few signals to analyze, plus tradeoff of time for space. Then,
>supposedly it can do a local scan to analyze a restricted region of
>visual space in more detai. Also with 2 retinas, it could do some form
>of rudimentary cross-correlation in order to extract depth info. Eg,
>scan both retinas outwards to focus on something closer-on, and vice
>versa. Retina-muscle feedback signals carry depth cues. Seems highly
>efficient.

I looked up Jumping Spider vision...(they're cute!)
a contrast to our own visual system. Thanks :)

found this on the evolution of eyes (photoreceptors)
http://jhered.oxfordjournals.org/cgi/content/abstract/96/3/171

:)

N.

.

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