Tuesday, November 17, 2009

The somniloquy hypothesis: How the immature brain learns facts

A while back I wrote about the possible adaptive function of somnambulism or sleep-walking. Well...I've come up with yet another hypothesis addressing an "abnormal" behavior falling under parasomnias.

Somniloquy or sleep-talking can happen during stages of REM or NREM sleep (I'm speaking to the latter). This seemingly bizarre behavior typically occurs in childhood and is outgrown by puberty. Presentation can vary from rhythmic nonsense words to long coherent speeches. No one really knows where it comes from. The most popular answer seems to be because of stress.

We could just leave it at that, but it doesn't really explain why the behavior came about in the first place (plus stress seems to play more of a role in REM somniloquy anyway). I have a hard time simply writing-off weird behaviors that have managed to stick around for long periods of time. In my head I'm thinking "there's just gotta be a functional purpose"!

Here's what I think NREM sleep-talking is all about. Many studies have shown that NREM sleep is where declarative memory (i.e. factual knowledge) is consolidated (Backhaus et. al, 2006, Daurat, Terrier, Foret, & Tiberge, 2007, Gais, & Born, 2004, Tucker et. al, 2006, Wagner, & Born, 2008). The presence of somniloquys is just evidence of this. It's a sign that the maturing brain is rehearsing and consolidating syntactic and semantic bits of information.

It's important to note that the calm quality of NREM sleep-talk is very different compared to the loud and emotional sleep-talk found during rapid eye movement behavior disorder. This makes a lot of sense. REM sleep is known to process emotional memory so of course you'd see this kind of late night emotionally charged verbal diarrhea. Some have postulated that this erratic unconscious behavior protected the stressed out sleep deprived caveman from hungry predators looking for some easy eats.

On the flip side, factual bits of data like "Paris is the capital of France" isn't emotional at all (unless you're strangely disturbed by this bit of info) and that's why you hear the flat affect during NREM somniloquy.

So there you go. I've laid out a tentative explanation for NREM somniloquys. I haven't seen anything else out there to explain this more pleasant form of sleep-talking (if do you spot any please let me know). However, the only way to really prove my hypothesis is by figuring out a way to induce somniloquys in different stages of sleep while observing the activity of the brain.

In the meantime, I wouldn't fret too much over your kids mumbling in their sleep something about world domination. They're probably just learning how to orate more effectively.

Gais S, & Born J (2004). Declarative memory consolidation: mechanisms acting during human sleep. Learning & memory (Cold Spring Harbor, N.Y.), 11 (6), 679-85 PMID: 15576885


Petit, D., Touchette, E., Tremblay, R., Boivin, M., & Montplaisir, J. (2007). Dyssomnias and Parasomnias in Early Childhood PEDIATRICS, 119 (5) DOI: 10.1542/peds.2006-2132

Backhaus J, Junghanns K, Born J, Hohaus K, Faasch F, & Hohagen F (2006). Impaired declarative memory consolidation during sleep in patients with primary insomnia: Influence of sleep architecture and nocturnal cortisol release. Biological psychiatry, 60 (12), 1324-30 PMID: 16876140

Daurat A, Terrier P, Foret J, & Tiberge M (2007). Slow wave sleep and recollection in recognition memory. Consciousness and cognition, 16 (2), 445-55 PMID: 16877007

Tucker MA, Hirota Y, Wamsley EJ, Lau H, Chaklader A, & Fishbein W (2006). A daytime nap containing solely non-REM sleep enhances declarative but not procedural memory. Neurobiology of learning and memory, 86 (2), 241-7 PMID: 16647282

Wagner, U., & Born, J. (2008). Memory consolidation during sleep: Interactive effects of sleep stages and HPA regulation Stress, 11 (1), 28-41 DOI: 10.1080/10253890701408822

3 comments:

  1. RE: The somniloquy hypothesis -- A misinterpretation of how adolescents learn facts in sleep!?

    So there you go. I've laid out a tentative explanation for NREM somniloquys. I haven't seen anything else out there to explain this more pleasant form of sleep-talking (if do you spot any please let me know). However, the only way to really prove my hypothesis is by figuring out a way to induce somniloquys in different stages of sleep and observe what the brain was doing.

    In the meantime, I wouldn't fret too much over your kids mumbling something about world domination as they nap. They're probably just learning how to orate more effectively.


    I think your conclusion is totally opposite to what I would have reached, if I were to apply my new (more dynamic and universal) theory of Memophorescenicity of Consciousness (or ME, in short) into your somniloquy hypothesis above.

    Briefly, as I just presented in “Human Consciousness and the end of Materialism -- RE: Can Neuroscience falsify Memophorescenicity of Consciousness in our Brain!?” (KnolGoogleUSA; November 2), my objective theory of ME -- mind and emotion (including morality and ethics): the intrinsic properties and contents that make each of us a very unique Self (young and old) especially in the thought-memory-recall dynamism within Oneself -- delves into 2 very basic and holistic and dynamic mechanisms:

    1) our memories are always modulated subconsciously in our brain, especially by the autonomous limbic (neuro-endocrino-cardiac) system (one which gives rise to our subconscious dreams, somniloquy, etc); and

    2) our memories can also be easily recalled and/or manipulated consciously by our (attentive) prefrontal cortex, the executive center, where our (intentional) thoughts of life experiences -- including feelings; perceptions; creations: real (as in science and technology) or imagined (as in religions and the spiritual concept of souls, gods, afterlife, heavens, etc) -- are all coordinated and generated physiologically -- especially in a neural, electrochemical dynamism of “particle-wave” function and “imagery” process, that I coined in my book Gods, Genes, Conscience (URL links below), as a holistic “psycho-panoramic” holography or topography of "memophorescenicity" -- or the ultimate quantum mechanics of consciousness and memory-recall phenomenon, in our brain!?

    While the freewill hypothesis falls into the consciousness-mechanism 2) above, as one that I explained before here: “Is inhibition a measure of freewill? -- RE: Absolutely!” (TheQuantumLobeChroniclesUSA; September 22); your somniloquy hypothesis shall now fall into the autonomous or subconscious-mechanism 1) above! (to be continued in Part 2 below).

    ReplyDelete
  2. Part 2: The somniloquy hypothesis -- A misinterpretation of how adolescents learn facts in sleep!?

    Consequently, and YES: Somniloquy or sleep-talking can happen during stages of REM or NREM sleep; as it all depends on the intensity of stress that one may incur during wake cycles or learning hours, in such a way that the higher intensity of stress that one had encountered, the more-bizarre somniloquys would occur during one’s sleep associated with REM or dreaming!

    As such, somniloquy (with or without REM) is not bizarre behavior at all; and typically it occurs in childhood and is outgrown (or accustomed to more stress intensity) by puberty; and its presentation -- one that can vary from rhythmic nonsense words to long coherent speeches, etc -- is just a typical reaction or response of the Broca’s area and associated cortex to the (autonomous) homeostatic modulation of the limbic system, during sleep.

    Whereas in the more-intense, neurohormonal homeostatic modulation, dreams (or imageries that incur in our visual cortex and associated region) would be further autonomously or subconsciously activated (or re-imaged or recalled in our brain) especially during REM sleep.

    Thus, contrary to yours and the conventional AI cognitive science materialist-reductionist assumptions and misinterpretations: Dreams and somniloquys are not actual learning experiences or mechanisms of learning in our brain, at all; they are both, nonetheless, the normal physiologic, representative byproducts of our wake-hour learning experiences and memory repertoire of learning -- or the Memophorescenicity of the Subconscious (and Consciousness) -- that are modulated or activated (and thus appearing bizarrely) especially by the subconscious, autonomous, neurohormonal homeostasis in our brain, especially during our sleep cycles!

    Best wishes, Mong 11/18/9usct4:03p; practical science-philosophy critic; author "Decoding Scientism" and "Consciousness & the Subconscious" (works in progress since July 2007), Gods, Genes, Conscience (iUniverse; 2006) and Gods, Genes, Conscience: Global Dialogues Now (blogging avidly since 2006).

    ReplyDelete
  3. "Dreams and somniloquys are not actual learning experiences or mechanisms of learning in our brain, at all; they are both, nonetheless, the normal physiologic, representative byproducts of our wake-hour learning experiences and memory repertoire of learning -- or the Memophorescenicity of the Subconscious (and Consciousness) -- that are modulated or activated (and thus appearing bizarrely) especially by the subconscious, autonomous, neurohormonal homeostasis in our brain, especially during our sleep cycles!"

    I don't agree, Where's the hard evidence? There's tons of data supporting the consolidating and reconsolidating effects of sleep on memory. Additionally, NREM sleep is very different from REM sleep, in EEG presentation and function. Therefore you can not equate REM somniloquy with NREM somniloquy. Thanks for the thoughtful comments.

    ReplyDelete