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Author Topic: Is heart just a pumping organ?  (Read 11780 times)

Offline deweys hamster

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Re: Is heart just a pumping organ?
« Reply #25 on: 14/08/2004 11:31:27 »
so is "alien hand" the same kind of thing that affects those people who have an arm or leg that they think is not theirs? don't know what it's called, but these folk want to have the offending limb amputated
 

Offline chris

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Re: Is heart just a pumping organ?
« Reply #26 on: 14/08/2004 13:25:27 »
Whilst I've been away this thread has covered a huge amount of ground. But to raise a few points which refer back to various points that have come up during the discussion...

Behaviour is genetically determined to a certain extent. But studies comparing identical twins separated at birth have failed to find any robust evidence for shared preferences or dislikes.

The brain is continually moulded by life experience, although this process occurs more easily in younger years than subsequently. At their peak, young children pick up and assimilate 10 news words a day. You try that now ! Even by teenage we require a teacher to help us grasp a foreign language. Yet all that was required for a baby was to listen to mum and dad !

In essence we are born with an undeveloped brain which is rather like a blank sheet of paper. The rough workings are there but they require 'tuning' through repeated experience. Take the visual system as an example. The connections from the eye to the brain are present at birth, but they are not precise - there are mistakes. But within a few weeks of birth, competition between different groups of nerve cells leads to the precise patterning of inputs (the ocular dominance columns) required for good vision.

Now superimpose onto this rough map the role of genetics. Say, for instance, there is a gene that leads to an increased density of inputs to the auditory system, providing someone with the opportunity to develop perfect pitch. Unless that person picks up an instrument and starts learning music, they will never exploit that potential.

So the brain is the meeting point of development (driven by genes) superimposed upon which is the influence of the environment and the life you lead. The bad news is that, as I suggested at the beginning of this piece, our brains are most plastic when we are at our youngest, so the saying "you can't teach an old dog new tricks" is, unfortunately, to a certain extent true.

Now to talk about the split brain preparation - this was the work that won Roger Sperry the nobel prize. A number of subjects underwent division of the corpus callosum (a large fibre bundle which connects the 2 halves of the brain together) in order to provide relief from epilepsy.

Just as the right side of the brain controls the left side of the body, everything you see on the left side of your body is processed by the right side of your brain. This left 'visual field' actually receives inputs from both eyes (cover your left eye and you'll still see some of the left visual field on the left). The inputs from the 2 eyes are combined on the opposite side of the brain.

This means that when a picture is flashed up in the right visual field it is 'seen' exclusively by the left side of the brain, and vice versa. In the split brain subjects, people shown say a cup in the right visual field were able to correctly name it as such (because the left brain encodes language). But when they were shown a cup in the left visual field, they knew what to do with it but they couldn't say what it was. This is because they couldn't transfer the identification of the object to the left brain to generate its name. Complicated, but very elegant work. Hence the nobel prize !

Chris

"I never forget a face, but in your case I'll make an exception"
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Offline qpan

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Re: Is heart just a pumping organ?
« Reply #27 on: 14/08/2004 17:22:47 »
quote:
Originally posted by chris

Behaviour is genetically determined to a certain extent. But studies comparing identical twins separated at birth have failed to find any robust evidence for shared preferences or dislikes.



Are you sure? The studies i read showed that provided the separated twins were approximately equally privelidged (i.e. they both went to school in the same country, parents of similar "social class"), they were shown to have very similar tastes as well as near identical IQ's. Granted, if one was spearated to california and the other went to somewhere like Bangladesh, you would expect them to have differing preferences and different IQ's.

I totally agree that nature and nurture are both extremely important in our upbringing - but this neither proves nor disproves free will.
If you make the assumption that there is no such thing as free will, then even nurture is completely dependant on DNA. The blank canvas of the brain is created with specifications depending on your genes, but how you fill the canvas is down to external stimuli from other humans as well as the environment. If there is no free will, then everything that happens around you just "happens," like a clock ticking, and you are just a gear inside the clock, unable to alter the time yourself.

"I have great faith in fools; self-confidence my friends call it."
-Edgar Allan Poe
 

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Re: Is heart just a pumping organ?
« Reply #27 on: 14/08/2004 17:22:47 »

 

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