Where in the mind is the seat of dreaming?

[strangerep]

In one million years, I've never heard anybody else ever mention such an experience.

Perhaps because it's hard to recognize. But it's happened to me too. I had a dream of a large hatch in the ceiling being slammed repeatedly, and it woke me. Then I realized the guy downstairs was having a problem with his garage door and was repeatedly slamming it.

I've also had music entering and integrating with dreams (though usually in a rather bizarre way, e.g., a cat singing the theme song from some TV show).

 

[.Scott]

Perhaps because it's hard to recognize. But it's happened to me too. I had a dream of a large hatch in the ceiling being slammed repeatedly, and it woke me. Then I realized the guy downstairs was having a problem with his garage door and was repeatedly slamming it.

I've also had music entering and integrating with dreams (though usually in a rather bizarre way, e.g., a cat singing the theme song from some TV show).

But did the dream of the large hatch include "back fill", dream script that related to the slamming but that you remember as occurring before the slamming started?

 

[strangerep]

But did the dream of the large hatch include "back fill", dream script that related to the slamming but that you remember as occurring before the slamming started?

Hmm... it was quite a few years ago. My (now vague) memory is that the dream consisted of some guy coming into the room and starting to slam the hatch repeatedly, for no apparent reason. So I guess there was a bit of backfill, but not much.

 

[Greg Bernhardt]

Like a script I've already read

For me it is the opposite. Things happen and are said in my dreams so mysteriously that I can't imagine my mind created.

 

[Drakkith]

For me it is the opposite. Things happen and are said in my dreams so mysteriously that I can't imagine my mind created.

Can't explain it? Must be aliens.

 

[lrq3000]

I studied a bit the theories about sleep and dreaming. Note that sleep's function is not really understood yet, so dream function and location can only be speculation at this stage.

From what I have read, there are two main theories about sleep function:

* Synaptic homeostasis (SHY) (Tononi & Cirelli, 2003) : wake LTP-potentiated synapses weights are normalized during sleep for efficiency.

* Memory trace replay (Lee & Wilson, 2002) : memories are consolidatedby offline reactivationduring sleep.

In both theories, sleep would serve as a regulation of plasticity, and thus would happen pretty much all over the brain. Dreaming could be a side effect of replaying the networks randomly to stabilize/optimize the weights and the networks topology.

This would neatly explain the results of a previous psychology study that observed that dreams content was pretty much random, with a bigger impact of repeatedly occurring events or emotionally charged events and little from recent events like watching movies. (sorry I don't have the ref, I read that a long time ago).

In addition, astrocytes have been shown to also participate in sleep regulation (see Fellin et al, 2014), so sleeping and dreaming might be a tad more complicated than just looking at neurons networks (which is already complex enough).

 

[Pythagorean]

I would call those two specific hypotheses relating to one general hypothesis of sleep (that it is for memory/processing) in which dreams might be relevant. The other main hypothesis is that it is for cell cleaning and maintenance - in which case dreams are simply a byproduct of the activation sequence.

The rest/maintenance hypothesis basically posits that most cells act slowly and can take turns in maintenance mode without affecting functionality, but since neurons are coupled electrically and always getting disturbed to maintain consciousness, the cells don't get a a chance to rest. Sleep then, is a process by which groups of neurons cycle through rest states in a complicated set of processes leading to loss of consciousness. The rest states would allow for aggregates to be cleaned out of the resting cells and tissue damage to be repaired. Partial consciousness (dreaming) is then an outcome of brain regions resting while others remain active.Of course, it's possible both hypotheses are valid, not just one or the other. But there has been some skeptical papers published about dreaming relating to memory.

 

[lrq3000]

Interesting hypothesis Pythagorean but unluckily I think unlikely, because it would posit that consciousness is incompatible with maintenance. In this case, constant lucid dreamers would suffer from sleep deprivation symptoms or at least a modification in their brain signature, which has been ruled out by the works of Stephen Laberge and some others. Indeed, they observed that being constantly conscious during your dreams does not impact the effects of sleeping (and you do not feel more tired or whatever after waking up).

I think we should avoid making any link between consciousness and dreaming, because they are clearly not incompatible given the findings from the studies on lucid dreams. Rather, unconsciousness might just be a byproduct of the sleep process, just for the security of the subject (to avoid moving around, as hypothesized to explain the "sleep paralysis" phenomenon).

But sleeping is obviously a very fundamental phenomenon since all living animals display this behavior, and suffer from sleep deprivation (up to death) if they stop sleeping. So sleeping must be a global phenomenon. If dreaming is a by-product of sleeping, then it's also probably global, if it is not, then all bets are open as to where it is located. It would be interesting to study dreaming on a wide range of taxons, to see if several branches of evolution display dreaming brain patterns, to check if this is a highly conservated brain function. If yes, then this would provide evidence that this function may be as common and basic as sleeping. Maybe such a study was already conducted?

 

[Pythagorean]

Consciousness isn't so much of a binary. So we don't lose full consciousness, just partial, as the whole brain (and relevant functions for consciousness) don't rest all at once.

Your extension about lucid dreamers is not consistent with the hypothesis. Once I have a computer, I'll be posting the relevant sources.

 

[Pythagorean]

as promised:

Cell maintenance hypothesis:
http://www.ncbi.nlm.nih.gov/pubmed/23635871

case against memory-sleep connection:
http://journals.cambridge.org/actio...age=online&aid=84269&fileId=S0140525X00004003

 

[lrq3000]

Thank you very much for the refs, very interesting reads.

About your hypothesis that sleep can partially affect some networks while others remain awake (I prefer to avoid "conscious" as I think this is yet another concept and function), Fellin et al 2014 referenced various articles that observed that in birds brains. I don't know if these observations were reproduced in humans though but I can bet they will be if that's not the case yet.

So your hypothesis that dreaming might be the byproduct of partial awakeness of some networks and sleeping of some others might be true, but this still contradicts with the findings that lucid dream was not observed to impact sleep effectiveness. Also, lucid dreams have been reported to happen sometimes during NREM dreams (see "Lucid dreaming during NREM sleep: Two case reports" by Tadas Stumbrys & Daniel Erlacher, 2012). Thus, even if sleep maintenance would happen only during NREM sleep, lucid dreaming would still potentially impact the process if "unwakeness" was required for the networks to be repaired, and it seems to not be the case.

/EDIT: still, sleep might be the moment where indeed a specific brain cell maintenance process happens, but the non-wakefulness still remains to be explained.

About the case against memory-sleep connection, that's an interesting read with fascinating cases, but the hypotheses I cited are not focusing only on REM sleep but rather on all sleep stages as a whole. Also the sleep homeostasis (which is accepted as a premisse in the "Cell maintenance hypothesis") is not directed only at memory but at network stability as a whole, memory consolidation being a side-effect of this network stabilization.