It's official - Substance D has been discovered...

[Fried Egg]

Skunk 'causes damage to vital nerve fibres'

Powerful "skunk weed" cannabis causes significant damage to vital nerve fibres linking the two halves of the brain, a study has found.

The damage occurs in the corpus callosum, the structure that allows communication between the brain's left and right hemispheres.

"Substance D" being, for those who don't know, the powerful psychoactive drug that the protagonist of "A Scanner Darkly" uses in his role as an undercover policeman that causes the two hemispheres of his brain to function independently.

Are there no limits to the man's prescience...

 

[Nick B]

You can sever the two hemispheres without adverse effect anyway. It has been used to stop siezures for some time. Some people have experienced the feeling of literaly being 'in two minds' though after the procedure.

 

[Ray McCarthy]

You can sever the two hemispheres without adverse effect anyway.

Without being crippled or dying. The effect can be strange.
Dolphins might drown if they went to sleep. They have the trick of sleeping one hemisphere at a time rather than true complete sleep. I wonder has anyone surgically modified learned how to do this?
We don't quite understand sleep, except that you really go a bit mad if you don't have any. Or worse.
Long-term total sleep deprivation has caused death in lab animals.

 

[Nick B]

Ive always felt sleep (as we experience it) to be a bit ridiculous from a survival point of view.

 

[Ursa major]

Ive always felt sleep (as we experience it) to be a bit ridiculous from a survival point of view.

And yet here we all are, just about every one of us needing to sleep regularly.

If there were humans out there who didn't need to sleep, one would have thought that their number, as a percentage of the population, would have increased, unless their increased (theoretical) survivability was of little or no practical use. (And that's without considering those who need a lot less sleep than the average human being.) But neither group -- no-sleepers, short-sleepers -- seems to be in the ascendant.

And if this doesn't convince anyone, I have a persuasive, one-word argument: cats.

 

[tinkerdan]

But cats are scanning all the time; and probably darkly too.

 

[mosaix]

You can sever the two hemispheres without adverse effect anyway. It has been used to stop siezures for some time. Some people have experienced the feeling of literaly being 'in two minds' though after the procedure.

Quite a few year ago I remember a researcher reporting some of the strange side effects of some experiments done on people who had had the procedure.

In one experiment the subject had both ears uncovered (so both hemispheres could hear), but the right eye covered (so only the right hemisphere could see - via the left eye). The subject was asked to pick up a pencil from the table.

Weirdly the subject said "I can't see a pencil." (Left, blind, hearing, speech-controlling, hemisphere talking). But as she spoke her left arm reached out and picked up the pencil. (Right, seeing, hearing, non-speech-controlling, hemisphere controlling and acting with the left arm).

 

[Nick B]

By, no adverse effect, i meant they are still able to function in their lives. I guess 'no adverse effect' was a little generous. It is a really interesting subject and delves into the duality of the persona. An interesting book that explores this a little (as part of a work that spans a wide range of subjects around the human condition) is The Holographic Universe. It has interesting theories but may be a little too out there for some.

 

[mosaix]

I think they get along fine, Quellist, as you say, as long as both hemispheres have the same 'inputs'. Fascinating stuff!

 

[Ray McCarthy]

cats.

If cats could eat and um, "go" without waking, they would.

 

[Vince W]

Cats don't walk, they strut.

 

[BAYLOR]

There is no like Phillip K Dick.

 

[Robert Zwilling]

Lately I've been thinking Substance D is a virtual product, Substance Digital, capable of disconnecting multiple sections of the mind from each other.