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Do we see dreams?

  1. May 16, 2017 #1
    I was thinking recently that when we dream and it appears to us in the dream that we are looking at objects, I was wondering if this dream vision originates from the same source as normal vision. That is in the waking world when we talk about 'seeing', we mean that photons from the Sun other other sources have reflected off objects and entered our eyes and ended up causing an electrical impulse to travel to a different part of the brain which then appears to us that we 'see' the object.

    So would this 'seeing' while awake, be similar electrical signals going to the same part of the brain as what causes us to appear to see things when we dream? Hope that was clear enough. Or is it a completely different brain mechanism.
  2. jcsd
  3. May 16, 2017 #2
    Since I seem to be the first person to post a response, let me say there are three ways those commenting can respond to your question:

    1) If they know the topic quite well, they can give you a brief accurate answer. However one difficulty they will have is to judge what level of depth to provide in their answer, since you have not indicated how much you know about vision yourself, and have also left your profile blank of any information about yourself that might be helpful. They can guess from the nature of your question that you probably know very little; but how little?

    2) If they don't have an exact answer, but are intrigued by this topic (for example if they're like me and have previously read a good deal about dreaming and about vision), they might do a quick Google and find an explanation that seems appropriate, and post it here. But they still will have the difficulty of not knowing how much you do or don't know yourself. Plus they may not actually want to do your work for you, since you too could Google.

    3) They can follow the spirit of the forum & forum guidelines & suggest that you do some preliminary research yourself, before posting such a wide-open question. This is how I am going to respond, in fact, because I think you'll get more out of posting that way.

    One big reason that I'd rather respond this way is that I have read enough about both vision and dreaming, and the neurophysiology of both, to be able to say that your initial assumptions about how vision works are inadequate. So anyone who tried to answer you directly would have to give you some very basic background information even before they get to the part about dreaming; but because you haven't indicated what your background is in biology or in any science at all, they won't know how to shape what they say so you can best understand it. So without realizing it, you're putting a big load on anyone who would like to help you.

    Anyway here are my suggestions:

    First, take a minute to check out this recent Insights article by forum member ZapperZ on why posting with no context isn't the best way to go in PF: https://www.physicsforums.com/insights/little-excuse-ask-question-cold/

    Second, expand your question with some background info: How much do you know about neurobiology, dreaming, etc.? What's your science background in general? Also, why does this question intrigue you & what to you hope to gain from asking? E.g. is it just a one-off, isolated question, or are you very interested in either vision or dreaming, possibly even doing a project of some sort? This will help those who know the topic well & might be inclined to at least give you a "quick and dirty" summary answer.

    Third - and this is optional, but recommended - consider doing at least some minimal research. At the very least this may help you better understand a "quick and dirty" answer if you get one. "Minimum" to me in this day and age means Googling for something like "human vision dreaming" and then patiently sorting through the hits until you get to those which look scholarly. Or perhaps searching in Wikipedia, or in known science sites such as Smithsonian magazine or Nature, etc. Or you can search for books on vision and/or dreaming, whether in your local public or school library or in a bookstore.

    I do have one book recommendation for you, if this is a topic that you're really interested in learning about - it's an inexpensive paperback (also Kindle ebook) in the "Very Short Introduction" series from Oxford University Press. They have a book on vision and also a book on dreaming; the book on dreaming is the one you would want, because it covers how the brain makes vision & other senses available to us while we dream: Dreaming: A Very Short Introduction, by J. Allan Hobson, Oxford U. Press, $8.94 on Amazon US.

    P.S. Also, if you're interested in learning more about research (e.g. if this wasn't something you were taught a great deal about in school), a book I often recommended when I was teaching is The Craft of Research: https://www.amazon.com/Research-Chi...=1494932815&sr=8-1&keywords=craft+of+research
    Last edited: May 16, 2017
  4. May 16, 2017 #3
    P.S. I forgot to add - as someone who enjoys reading about both vision & dreams (usually separately), I do like your question a lot, as both these processes are fascinating. So I encourage you to stick with it & maybe flesh the context out a bit more as suggested.

    Here is one way to think about the question that you might find intriguing: "Do blind people see in their dreams?" (This is literally a question that gets discussed in the "Very Short Introduction" book I recommended above.) There is more than one answer, and which answer is correct for a given situation depends on a fundamental aspect of vision.
    Last edited: May 16, 2017
  5. May 17, 2017 #4


    Staff: Mentor

    @bland are you asking simply if the visual cortex gets activated during REM sleep? Or is your question something different?
  6. May 17, 2017 #5
    A simple answer is no. We don't SEE light reflecting from our eyes when we dream, because there is no image. It's essentially just a stream of memories.
  7. May 17, 2017 #6
    This is inaccurate; and though I'm sure well-meant, not helpful to the OP. Again, given that this is a science forum, it would behoove folks who aren't familiar with the physiology of vision to actually do some reading on the subject before commenting.

    I also suggest folks wait for the OP to get involved again. He is the one who asked the original question; he's been invited at least twice now to clarify; let's give him some time to do so.
    Last edited: May 17, 2017
  8. Jun 4, 2017 #7
    Some areas of the brain the activities of which are closely correlated with processing of normal visual information are also highly active during REM sleep and less active during non-REM sleep.
  9. Jun 5, 2017 #8
    Sometimes I recall dream scenes later, when I am awake.
    These seem just as visually real as a memory of a real life event.
    (Even though, being a dream, the actual circumstances can be bizarre, for example I am able to fly)
  10. Jun 5, 2017 #9


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    Staff: Mentor

    The OP hasn't been back to the forum since they started this thread, so I wouldn't wait for them.
  11. Jun 5, 2017 #10


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    I don't remember dreams that much, but I do have fairly strong visual imagery when I think about certain things.
    Sometimes I can see vague graphs, layouts, or diagrams, somewhat like an overlay on the ordinary visual reality.
    If I want to think about these things more intensely I look away from people (faces can be very distracting), at a homogeneous area (like a wall) or close my eyes.
    Sometimes I can get very vivid images of things (kind of like cartoons) with closed eyes.

    These may be like waking dreams, I don't know, but they do seem to compete with eye driven imagery.
    Nor do I have any idea where all this might be occurring in the brain.
  12. Jun 5, 2017 #11


    Staff: Mentor

    Yes, but not the primary visual cortex.
  13. Jun 6, 2017 #12
    As a general FYI - back in my comment #3, I posed the question, "Do blind people see in their dreams?" I also asserted that "There is more than one answer, and which answer is correct for a given situation depends on a fundamental aspect of vision."

    The answer turns out to be, "It depends on when you went blind." In a very general way, persons who are born blind (and never develop vision thereafter) don't see in their dreams, while persons who are born sighted, and lose sight only some years after infancy, typically do see in their dreams. The "fundamental aspect of vision" that I mentioned is merely that although we humans are born with what amounts to an "Ikea hardware kit" for vision, i.e. the necessary physical apparatus, "some assembly is required" - i.e., it actually takes quite some time after birth for this apparatus to develop; in particular, as I remember it, vision networks in the brain require a massive amount of real-time "learning" to make all the necessary connections and become functional. That isn't a very technical way of putting it, but it's what I remember from a huge amount of reading I did some years back on color vision.

    So for someone blind from birth (or prior to to birth), these vision networks and so forth will never have had the chance to develop as they do in sighted people; thus won't be available to facilitate visual activity during dreaming, any more than when awake. I did a quick Google and one article I came across (this is the second cite below) says specifically that:

    . . . people who are blinded after the age of 5–7 seem to have visual imagination and dream with visual imagery throughout life, while blinding at an earlier age leads to absence of visualization in both waking and dreaming.​

    As to how this relates to the OP's original question about how we "see" in dreams - as I say my reading was years ago, so I can't any longer say exactly which parts of the brain do what; but the above clearly implies that "seeing" is a complex behavior that goes far beyond "light entering the eyes"; we have not merely rods and cones and so forth, but the necessary neural machinery to do huge amounts of what we could call "data processing", in which raw signals are transformed into many different kinds of meaning - e.g., color is processed separately from form and motion, as explained in this encyclopedia entry on color vision. As we might expect, a great deal, though not all, of this neural machinery is available to us when we "see" images without using our eyes, i.e. when daydreaming, imagining, or dreaming.

    I don't have my reading materials from back then with me - they are in a box somewhere - but I did find a couple of reasonably recent review articles on this question of whether the blind can see in dreams - cites below. The first is on the development of human vision in detail, while the second is more to do with how science looks at the dreaming brain; it briefly mentions the development of vision. Both papers have free PDF downloads.

    Oliver Braddick, Janette Atkinson, Development of human visual function, Vision Research, Volume 51, Issue 13, 1 July 2011, Pages 1588-1609, ISSN 0042-6989, https://doi.org/10.1016/j.visres.2011.02.018

    Nir, Y., & Tononi, G. (2010). Dreaming and the brain: from phenomenology to neurophysiology. Trends in Cognitive Sciences, 14(2), 88. http://doi.org/10.1016/j.tics.2009.12.001

    There is also a Smithsonian article I found that touches on this, in discussing a survey of which of the five senses blind persons report in dreams (e.g. touch, smell, vision, etc.): http://phenomena.nationalgeographic.com/2014/02/26/how-the-blind-dream/
    Last edited: Jun 6, 2017
  14. Jun 11, 2017 #13
    First I should apologise if I appeared rude by not returning sooner. I knew I'd be back and I wanted to be able to answer properly, however life sort of got in the way, not to mention being diagnosed with cancer, but I had an operation a few weeks ago and I think that's the end of it, I'll know for sure in a few months.

    I read ZapperZ which was helpful and I have 'Dreaming' on the way from the UK to Australia, only cost $14AUD including delivery! So I'll be looking forward to that. I've also filled in my profile.

    btw, The Craft Of Research book you suggest looks like it's going to be very serendipitously useful for the body of work I'm currently writing and I'm excited and happy you pointed me to it, thanks.

    Yes I've often thought about that question what blind from birth people see, and I'll be looking forward to the arrival of the book. Actually my question was pretty much as it read. I understand 'seeing' is a very complex set of brain activities, but in my original question I was really only looking for a basic 'wiring' answer, but the more I think about the question the more I disappear down a rabbit hole. Basically though my question, if I flesh it out a bit more was....

    From what I understand, electrical signals from the auditory neurones and electrical signals from the optic nerve are physically the same thing but they go to different parts of the brain, one becomes sound and one becomes images. When a simple image that is in your dream is perceived, does this perception of the image happen in the same part of the brain as when the same image is perceived in the waking state. I'm just talking about the perception of the image, not any emotional responses or understanding of the purpose of the object which I imagine would have other parts of the brain involved. OR do images that appear in your mind in dreams come about by totally different parts of the brain. I've re written this paragraph three times now and I can see my question is becoming problematic.

    Pretty much, yes that is what I'm asking.

    Yes that is an excellent point and in trying to reformulate my question I'm trying to separate out the emotional processing from the simple formation of the image. For example I get from lectures on the brain by Prof Jeannette Norden and Books like the Man Who Mistook his Wife for a Hat, that separate to seeing something there's the processing required to actually recognise the object. It may very well be possible that my question cannot be answered. Or perhaps can be answered using a different analogy. For example a person who can see faces but he doesn't recognise who the face is. With that in mind my question would not be concerned with whether or not he recognised the face, simply that even if his brain was wonky and he did not recognise the face of his wife would the part of his brain that at least saw the face be the same part of his brain that 'saw' a face, any face, in a dream?
  15. Jun 11, 2017 #14
    Sorry to hear about the cancer - definitely a major life event - hope the operation went well.

    In terms of eye versus ear, obviously these organs are very different and so the raw data from each will be different; beyond that I know only that there are a vast number of processes that support the transmission of various types of messages in the nervous system; someone better up on biology could tell you more.

    Also, as I think I mentioned, my reading on vision was too long ago for me to remember what parts of the brain do what; my current reading related to the brain has to do with pain vs. nociception, and one thing that is new to me is that in that field (pain research), models have evolved such that rather than particular functions being assigned to specific brain regions only, the more modern view is that a great deal of redundant or parallel processing goes on. But whether this is in any way the case for vision also, I have no idea.

    Glad you are expecting the book & I hope you enjoy the reading and the learning!
    Last edited: Jun 11, 2017
  16. Jun 11, 2017 #15
    The organs are different but the nerve impulse that travels down the neurone will be the same thing just organised differently, yes? I guess if optic nerve impulse went to the sound processing parts of the brain, it would just end up as noise, I'm guessing. Sort of like the way, all the stuff on your computer whether pictures or sounds that are sent to the processor are the same basic components, that is a particular orientation of an electronic state. On or off. I've since found the audiobook version of Dreaming and I've just loaded it up on my iPod and will be listening to it tonight, ironically it will likely go into my dreams like most stuff I listen to at night. It get's quite odd at times, but also interesting the way these lectures or books manifest in a dream.

    Cancer was in the prostate, completely contained inside the capsule and they removed whole gland and left the nerves intact with the Da Vinci robotic playstation gadget, and all seems fine with the world again. It's like nothing ever happened. I'm not really bothered about it now, as it sort of makes sense with regards to the work I'm currently writing. Just another episode in the ongoing play that is my strange life.
  17. Jun 11, 2017 #16


    Staff: Mentor

    That is very scary! I hope things go well with the treatments

    That one at least has a clear answer. The primary visual cortex is not activated during REM sleep.
  18. Jun 16, 2017 #17
    I think this is a very interesting question. I take the OP's question to mean quite simply is conscious awareness of dreams derived from the same neural mechanisms as conscious awareness of sensory input. I have often wondered about this myself and in the absence of any detailed knowledge I was curious to see what answers would be forthcoming.

    My assumption about this is that yes, whatever makes us conscious of normal sensory input makes us conscious of dreams. However that is a different thing from whether or not all of the visual processing centres are stimulated equally in dreaming and vision.

    As an earlier commenter said, many parts of the visual system are stimulated by dreams, but surely this would be in the same way that memory processes activate contributing processing centres? In other words, wouldn't the physical mechanism for "seeing" dreams deeply implicate the hippocampus and related memory processes?
    Last edited: Jun 16, 2017
  19. Jun 16, 2017 #18
    Ahhh. A little Google action seems to point to that very thing, so I'm glad my guess is well founded. Dream processes appear to more than likely arise from memory processes and therefore rely upon hippocampal activity. Which makes sense as both dreaming and imagination cannot be using actual sensory input to generate conscious experience (though I'd assume some level of input still occurs during sleep?).

    I hadn't realised that dreaming is still relatively unexplained given that it seems a fairly straight-forward event, but unravelling the complexity of brain function is a daunting task. I also assume that anyone well read in the field knows about the relationship between memory and dreaming, which I didn't until just now!

    In terms of the original question then, the answer is something like no, the processes for actual seeing and dreaming are different, utilising some shared regions of the brain but not all. Seeing involves processing of sensory input through a defined sequence of visual centres with plenty of feedback and input from other regions to arrive at a presented representation in consciousness, whereas dreaming activates some of these areas to retrieve stored representations which are then represented to consciousness. The actual mechanism by which representations of any origin become conscious is not yet known, but presumably is the same in any case. Does that seem like a fair summary?

    This paper offers a sort of brief summary of recent thinking about memory/hippocampal involvement in dreaming:


    From the paper:
    "One of the main structures involved in memory storage and also believed to contribute to the creation of dream images is the hippocampus. Research has brought forth evidence of this involvement, including one study showing that hippocampus function is higher during REM sleep, than during both Non-REM sleep or waking (Nielsen & Stenstrom, 2005). While this increased Hippocampal function does not represent a casual relationship between its function and the creation of dream images in REM sleep, there are several lines of evidence that support the idea that the hippocampus is involved in dream image production.
  20. Jun 17, 2017 at 2:20 AM #19
    You're correct that the hippocampus is involved in dreaming, along with the rest of the limbic system; however the simple notion of dividing seeing into active seeing, when there is input from the eyes, versus passive retrieval of stored images, when there is no input from the eyes, is insufficient for explaining vision and/or visual imagery in dreams. Remember that we can imagine (whether our eyes are open or closed) infinitely many things we have never seen; this supports what I dimly recall from my prior reading, which is that visual imagination does not rely solely on literal memories; rather, the system as a whole has the ability to create entirely new composite images that make use of the same qualities of images our brain learned to process when we were very young & our vision was still forming: e.g. motion, form, color, brightness, edges, etc. - I don't know all the right terms, but the categories are quite elaborate. (And interestingly, it is these categories of processing that give rise to optical illusions). This is not to say that we don't remember images themselves; we do; but recall is not the only process involved in vision in dreams. So when thinking of image qualities or categories, these are not "memories" but more like "capabilities" that enable meaningful perception.

    But regardless, thanks for posting your thoughts; you got my own curiosity going again on what you rightly say is a very interesting topic. Since my books on vision are still misplaced, I made another try at digging up relevant information online. I found a simple "explainer" web site about the brain, The Brain From Top To Bottom; it was developed by a Canadian neuroscientist, Bruno Dubuc, and sponsored by McGill University, in Quebec. In 2005 the site received an award from MERLOT for outstanding public education, so I think it has credibility. Anyway to quote from the page on brain function during sleeping:

    Brain imaging studies have found, for example, that the primary visual cortex, the first part of the brain involved in consciously decoding visual signals when people are awake, shows very little activity when they are dreaming during REM sleep. This is no surprise—when people are dreaming, their eyes are closed, and no visual signals are reaching them.

    But brain imaging studies have also shown that certain extrastriate visual areas of the cortex, which decode complex visual scenes, are significantly more active during REM sleep. Thus, during REM sleep, these areas are apparently involved in analyzing complex visual scenes. This is completely consistent with the often highly elaborate visual dream scenes that people report when researchers awaken them from REM sleep.

    During REM sleep, intense activity is also observed in the limbic system, a set of structures heavily involved in emotions. Two of these structures are especially active: the hippocampal region and, in particular, the amygdala. Once again, it is interesting to note that this intense limbic activity does not occur during the phases of non-REM sleep, when the dreams that people have are far less emotional.​

    You can find more information on these "extrastriate visual areas" via the links in the excerpt above; and also in Wikipedia's article on the visual cortex. A crude way of putting it is that the primary visual cortex, also known as V1, begins the processing of the most essential aspects of vision, e.g. detecting motion and recognizing patterns; areas V2 through V5 deal with further aspects. All this accords with what I have read in the little book I recommended to the OP, Dreaming: A Very Short Introduction, by the researcher J. Alan Hobson, as well as other sources; Hobson calls these additional visual areas in the brain "associative" to distinguish them from primary.

    So back to the question of memory as a basis for seeing in dreams: From the reading I've managed to do, one model being used these days has to do with "encodings" of images or image qualities which have been previously processed by the various secondary areas of the visual cortex mentioned above. These days, with fMRI machines running around loose looking for expensive projects to do, apparently research has turned to some pretty interesting ways of looking at such encodings. Specifically, I found at least two studies that use fMRI and computerized algorithms called "decoders" to explore visual encodings in dreams; very technical, but fortunately I also found a couple of blog posts where others who follow this kind of research explain the studies in language suited for laypersons.

    In closing, here are links for one of these studies, "Neural Decoding of Visual Imagery During Sleep"; it was first published in Science, May 3, 2013:
    I'll leave it at that for now. I'll be interested to see what the OP comes up with in his own reading later on.
    Last edited: Jun 17, 2017 at 5:03 AM
  21. Jun 17, 2017 at 6:32 AM #20
    Thanks for these links, UsableThought, I'll read them as soon as I can. It's an intriguing area of study, as I say I've often wondered about dreaming/imagination but haven't really dug into it. I had previously found Dubuc's website and agree it's an excellent resource, I'll have to get back to it on this subject.

    One small point - I don't mean to say that imagination or dreaming implies "passive retrieval of stored images". My suggestion in that sense was that the hippocampus activates stored representations to compose dream sequences (or imaginative sequences), but such representations are not necessarily static images as such - rather they might take the form of more abstract or fundamental elements of visual processing.

    Some of the material I have read proposes that the hippocampus is involved in detailed scenario construction and the playing out of possible behavioural options, for example the case of London taxi drivers whose hippocampi increase in size to better store 3D representations of locational arrangements and thereby simulate (imagine) potential solutions to paths through these locations (http://www.pnas.org/content/97/8/4398.full).

    Presumably in imagination, we utilise the hippocampus to generate potential scenarios that are composed of both static images as well as more elemental representations, including emotional salience to such scenarios.

    But I wonder whether dreams work in that sort of directed fashion. My guess is that we are "seeing" image sequences (or whatever modality the dream content takes) that derive from a mix of stimulus (for example representations that arrive at the hippocampus during memory consolidation: http://learnmem.cshlp.org/content/11/6/671.short) and which are then inserted into meaningful sequences by the same engine that drives imagination. Just a guess, mind you, but I would be surprised if that guess is a long way from the reality (http://www.jneurosci.org/content/27/52/14365.short).

    What I find most engaging about this possibility is that conscious awareness of imagination, dreams and external sensory stimulus (ie "reality") might presumably occur on the scaffold of a common process...

    Anyway, thanks again for all these great links, I look forward to reading further.
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