4 ms·

My first reaction was that it seems so inefficient to bring the entire computer online just to maintain its temperature - which could be controlled physically u

My first reaction was that it seems so inefficient to bring the entire computer online just to maintain its temperature - which could be controlled physically using blood. But couldn't we test this by artificially keeping the brain warm and seeing what sleep patterns emerge?

creep 8y ago
As an anecdote, I always have intense dreams with fever. I'm prone to kidney infections so I experience this often. My head is clearly very warm, my brain swells a little with the heat, and my dreams are clear and intense.
- spydum 8y ago
  this would seem likely because you aren't sleeping well or deeply, hence able to recall the dreams.
  - creep 8y ago
    I usually recall my dreams, fever or not. There is a marked difference between them.
stepik777 8y ago
> it seems so inefficient to bring the entire computer online just to maintain its temperature In what sense is it inefficient? In terms of energy 100% is converted to heat anyway
- manmal 8y ago
  Some of that should be converted into lowering entropy (building neural structures etc) so I don’t think 100% escapes as heat.
iforgotpassword 8y ago
thats what i thought. seems easy enough to do. I'd like to see more evidence to support that theory, I'm rather sceptical. i was remembered of that very rare condition where your brain cannot ever enter the deeper sleep states. these people usually die rather soon after onset of exhaustion. what has been confirmed through these people is that narcotics dont help at all. while you can ise it to make them 'sleep' long enough, it's not helping with the condition. so brain warming cannot be the main reason for REM, if it's one at all. edit: fatal insomnia is what i was referring to.
derefr 8y ago
My own understanding of this, as a layman who has been driven by curiosity to read a bunch of journal papers on the subject: Consider the developmental paths of cell differentiation/specialization over the evolutionary history of animal species. Neural cells and muscle cells both have a common progenitor cell (i.e. a stem cell will differentiate into this cell, which then has one or the other as potential descendants.) This sort of means that there is "code sharing" going on between the structure of nerve and muscle cells, moreso than between these and, say, liver cells. And, since animal muscle cells evolved before animal nerve cells, it's likely that it's directional—it's less that these are two "classes" with a common, well-factored "parent class"; and more like nerve cells are a "subclass" that has something closer to muscle cell functionality in its "parent class", and overrides that functionality heavily until it does what it wants. Or, to put that another way: ignoring the particular way nerve tissue structures itself, and the receptors it grows, etc. Functionally, nerve tissue is, effectively, just muscle tissue that is balanced very precariously by its electrochemical environment to be in an always semi-conducting state, where the tissue as a whole will never go all-the-way-resistive (that's excitotoxicity, both in muscles and in nerves) or all-the-way-conductive (that's flexion in a muscle; but that's a seizure in a nerve. For the nerve-as-muscle, that's okay, it's built for that; but for the nerve-as-controller-of-functioning-elsewhere, that messes things up.) Nerve cells rely on a lot of the code they've "inherited" from their muscle-cell "parent class" for their functioning. This includes the part where muscle tissue (and so nerve tissue) gets oxygenated by pumping its own blood through it [and clears waste by pumping its own lymph through it], by inducing subtle sinusoidal increases/decreases in electrical activity to cause increases/decreases in capillary diameter. This is especially important for the brain, given that the blood-brain barrier prevents blood from being "driven" through the brain by the heart. The brain has to pump itself, and therefore has to induce electrical activity in itself. For the brain-as-muscle, this electrical activity is useful. For the brain-as-neural-network, this electrical activity is—from what I understand—a form of interference to the signal the brain is trying to propagate/compute. The brain has evolved to deal well enough with this interference to make it not get in the way of accomplishing the goals the brain was evolved to accomplish; but, necessarily, evolution never bothers to go any further than that. So, as long as the effects are "harmless" to adaptive fitness, that interference is allowed to leak through as a signal interpreted by the brain-as-neural-network as thought, or perception, or what-have-you. And thus, dreams.
vertexFarm 8y ago
If heating is your goal, thermal inefficiency isn't really a problem. There's also the issue of the blood-brain barrier. Might make normal thermal regulation insufficient. In any case, it seems like they intend to do further study to see if this hypothesis is really correct and if there is more to the story. Who knows--it might be that for some species it's not necessary, but left over as a vestigial behavior like a tailbone. That's pure conjecture on my part, excuse me. Something I find interesting about this, if a little off-topic, is that the Ancient Egyptians had a misconception that the brain simply existed to cool the blood. When they mummified a body they threw that part in the trash. How far we've come.
- Smaug123 8y ago
  "If heating is your goal, thermal inefficiency isn't really a problem." - I guess my objection is based on an analogy with human-made devices, which degrade the more you use them. Thermodynamically it's fine to power up a computer to produce heat, but the inefficiency I really meant is that every moment the computer is running is another moment when it can go wrong. Perhaps the brain isn't like that: perhaps the brain's activity doesn't change the mind's lifespan. Or, more prosaically, perhaps the mind does degrade faster if it's active more, but evolution didn't care as long as the meatbags kept pumping out their genes.
  - vertexFarm 8y ago
    True, that's a good point. As far as evolution is concerned, if you have effectively raised offspring until you aren't fertile anymore then the warranty is up and all the time you get after that is a bonus. There isn't really much pressure to select for longevity after that period. I've heard a lot of office buildings will leave every floor's fluorescent lights on in the winter to take a load off the overnight heating bills. I'm sure that lessens the lifespan of the bulbs and ballasts, but for people to adopt that practice it must still be economical in the final tally. Who knows, I'd love to see more study on this because I think everybody in history has always wondered what the hell is up with dreams. "To keep your noggin warm" seems like a super anticlimactic purpose and I love it. It's so absurd and nihilistic it's funny, which kind of jives with nature's whole style.
djsumdog 8y ago
We're talking about biological evolution here. There's no design process, except by chance and fitness. Even some traits that might be better for an animal may not make it -- there's a whole chance and probably thing there. There is a paper where some researchers look at biological processes vs computer software. Biological processes seem to have a lot of repetition between systems: http://www.pnas.org/content/107/20/9186.full http://www.pnas.org/content/107/20/9186.full

creep 8y ago

As an anecdote, I always have intense dreams with fever. I'm prone to kidney infections so I experience this often. My head is clearly very warm, my brain swells a little with the heat, and my dreams are clear and intense.

spydum 8y ago
this would seem likely because you aren't sleeping well or deeply, hence able to recall the dreams.
- creep 8y ago
  I usually recall my dreams, fever or not. There is a marked difference between them.

stepik777 8y ago

> it seems so inefficient to bring the entire computer online just to maintain its temperature In what sense is it inefficient? In terms of energy 100% is converted to heat anyway

manmal 8y ago
Some of that should be converted into lowering entropy (building neural structures etc) so I don’t think 100% escapes as heat.

iforgotpassword 8y ago

thats what i thought. seems easy enough to do. I'd like to see more evidence to support that theory, I'm rather sceptical. i was remembered of that very rare condition where your brain cannot ever enter the deeper sleep states. these people usually die rather soon after onset of exhaustion. what has been confirmed through these people is that narcotics dont help at all. while you can ise it to make them 'sleep' long enough, it's not helping with the condition. so brain warming cannot be the main reason for REM, if it's one at all. edit: fatal insomnia is what i was referring to.

derefr 8y ago

My own understanding of this, as a layman who has been driven by curiosity to read a bunch of journal papers on the subject: Consider the developmental paths of cell differentiation/specialization over the evolutionary history of animal species. Neural cells and muscle cells both have a common progenitor cell (i.e. a stem cell will differentiate into this cell, which then has one or the other as potential descendants.) This sort of means that there is "code sharing" going on between the structure of nerve and muscle cells, moreso than between these and, say, liver cells. And, since animal muscle cells evolved before animal nerve cells, it's likely that it's directional—it's less that these are two "classes" with a common, well-factored "parent class"; and more like nerve cells are a "subclass" that has something closer to muscle cell functionality in its "parent class", and overrides that functionality heavily until it does what it wants. Or, to put that another way: ignoring the particular way nerve tissue structures itself, and the receptors it grows, etc. Functionally, nerve tissue is, effectively, just muscle tissue that is balanced very precariously by its electrochemical environment to be in an always semi-conducting state, where the tissue as a whole will never go all-the-way-resistive (that's excitotoxicity, both in muscles and in nerves) or all-the-way-conductive (that's flexion in a muscle; but that's a seizure in a nerve. For the nerve-as-muscle, that's okay, it's built for that; but for the nerve-as-controller-of-functioning-elsewhere, that messes things up.) Nerve cells rely on a lot of the code they've "inherited" from their muscle-cell "parent class" for their functioning. This includes the part where muscle tissue (and so nerve tissue) gets oxygenated by pumping its own blood through it [and clears waste by pumping its own lymph through it], by inducing subtle sinusoidal increases/decreases in electrical activity to cause increases/decreases in capillary diameter. This is especially important for the brain, given that the blood-brain barrier prevents blood from being "driven" through the brain by the heart. The brain has to pump itself, and therefore has to induce electrical activity in itself. For the brain-as-muscle, this electrical activity is useful. For the brain-as-neural-network, this electrical activity is—from what I understand—a form of interference to the signal the brain is trying to propagate/compute. The brain has evolved to deal well enough with this interference to make it not get in the way of accomplishing the goals the brain was evolved to accomplish; but, necessarily, evolution never bothers to go any further than that. So, as long as the effects are "harmless" to adaptive fitness, that interference is allowed to leak through as a signal interpreted by the brain-as-neural-network as thought, or perception, or what-have-you. And thus, dreams.

vertexFarm 8y ago

If heating is your goal, thermal inefficiency isn't really a problem. There's also the issue of the blood-brain barrier. Might make normal thermal regulation insufficient. In any case, it seems like they intend to do further study to see if this hypothesis is really correct and if there is more to the story. Who knows--it might be that for some species it's not necessary, but left over as a vestigial behavior like a tailbone. That's pure conjecture on my part, excuse me. Something I find interesting about this, if a little off-topic, is that the Ancient Egyptians had a misconception that the brain simply existed to cool the blood. When they mummified a body they threw that part in the trash. How far we've come.

Smaug123 8y ago
"If heating is your goal, thermal inefficiency isn't really a problem." - I guess my objection is based on an analogy with human-made devices, which degrade the more you use them. Thermodynamically it's fine to power up a computer to produce heat, but the inefficiency I really meant is that every moment the computer is running is another moment when it can go wrong. Perhaps the brain isn't like that: perhaps the brain's activity doesn't change the mind's lifespan. Or, more prosaically, perhaps the mind does degrade faster if it's active more, but evolution didn't care as long as the meatbags kept pumping out their genes.
- vertexFarm 8y ago
  True, that's a good point. As far as evolution is concerned, if you have effectively raised offspring until you aren't fertile anymore then the warranty is up and all the time you get after that is a bonus. There isn't really much pressure to select for longevity after that period. I've heard a lot of office buildings will leave every floor's fluorescent lights on in the winter to take a load off the overnight heating bills. I'm sure that lessens the lifespan of the bulbs and ballasts, but for people to adopt that practice it must still be economical in the final tally. Who knows, I'd love to see more study on this because I think everybody in history has always wondered what the hell is up with dreams. "To keep your noggin warm" seems like a super anticlimactic purpose and I love it. It's so absurd and nihilistic it's funny, which kind of jives with nature's whole style.

djsumdog 8y ago

We're talking about biological evolution here. There's no design process, except by chance and fitness. Even some traits that might be better for an animal may not make it -- there's a whole chance and probably thing there. There is a paper where some researchers look at biological processes vs computer software. Biological processes seem to have a lot of repetition between systems: http://www.pnas.org/content/107/20/9186.full http://www.pnas.org/content/107/20/9186.full