Do Blind People 'see' anything when they dream?

[Xander]

If the following question were answered, it would also answer the original question:

Do blind people ever SEE there Life "flash before their 'eyes'"? It is the exact same concept of dreaming, because no tangable nor "real" existing objects are being seen but rather "figments" of their imagination. So if blind people can IMAGINE, then YES, they can see their dreams.

[Capitalist Pig]

Okay, here's the full text of the article:

Visual Dreams In The Congenitally Blind?
Fernando H. Lopes da Silva silva@science.uva.nl
Trends in Cognitive Sciences 2003, 7:328-330

Neurobiology Section, Swammerdam Institute for Life Sciences, University of Amsterdam, The Netherlands

Abstract

An EEG study of sleep in congenitally blind persons revealed a significant correlation between the visual activity reported during dreaming and the decrease of alpha strength recorded from the central and occipital regions of the scalp. This provides the first objective evidence that subjects who have never had visual experiences can have dreams with virtual images that are probably mediated by the activation of the cortical areas responsible for visual representations.

Whether the congenitally blind have dreams with visual content has been a controversial subject for a long time, and is still open to question[1–3] . A fundamental problem of this inquiry is that most studies have been limited to subjective assessments.

Dreams with visual content are expressions of visual imagery. Therefore if dreams with visual content could be demonstrated in congenitally blind persons, this would imply that visual imagery is possible in subjects who have been prevented from having visual experiences. Furthermore, this would allow one to infer that visual imagery does not depend on specific visual perception, but can emerge from activation of visual cortex by non-visual inputs.

This issue was recently raised again by an intriguing finding reported by Bertolo et al.[4]. These authors used an indirect method to assess whether dreams with visual content occur in the congenitally blind, namely EEG recordings obtained during sleep. Bértolo et al.[4] based their analysis on the assumption that the pattern of cortical activation during dreams with visual content would be similar to that during visual imagery, and that this pattern would be reflected in a change of the scalp EEG alpha-rhythm. Indeed, visual imagery in normal subjects is generally accompanied by a decrease of alpha activity (8–12 Hz) recorded from the scalp[5] They therefore recorded the EEG from the occipital and central scalp areas of blind subjects whose sleep was continuously monitored. The subjects were awakened every 90 minutes to be questioned about their dream recall, and the authors carried out a spectral analysis of the EEG preceding the moment of awakening.

In addition the subjects were asked to make a drawing of one of their dream scenes. The dream reports of the congenitally blind were vivid with tactile, auditory and kinesthetic components but surprisingly, also with visual content. Bértolo et al. defined a visual activity index by performing a quantitative analysis of dream content[6]. The analysis revealed a significant correlation between this visual activity index and the decrease of alpha strength. Furthermore the congenitally blind subjects were able not only to describe their dreams verbally, but also to make graphical representations of their content (Fig. 1). The main conclusion from the study is that the dreams of congenitally blind subjects involve the activation of areas of the cortex that are responsible for visual representations.


Fig. 1: Graphical representation of a dreamed scene by a blind subject. Reproduced with permission[4].

A number of issues can be raised in the context of these findings:

(1) One issue is methodological: what is the functional significance of a decrease of EEG spectral power (8–12 Hz) in the context of sleep physiology?

(2) Another issue is neurophysiological: how can activation of visual cortical areas in congenitally blind subjects be explained in terms of the functional anatomy of the brain?

(3) Still another is cognitive: how can visual imagery occur in subjects who have never had visual experiences?

Is EEG alpha activity an unequivocal indicator of activation of the visual cortex?

In the context of the methodological question, we must note that within the frequency range 8–12 Hz different rhythmic activities can be distinguished: mainly the alpha-rhythms of the visual cortical areas and the mu-rhythms of the sensorimotor areas[7]. During rapid-eye-movement (REM) sleep, the sleep state in which dreaming preferentially occurs, two variants of alpha activity with different functional roles have been described[8]: alpha activity that is modulated over occipital regions by the presence of rapid eye movements; and REM-alpha bursts, independent of the presence of rapid eye movements, which could correspond to micro-arousals. The former alpha activity is blocked over occipital regions when rapid eye movements are present, so this might be an electrophysiological correlate of visual-dream content[9]. The parameter that Bértolo et al. used in their study is more likely to be the former variant of alpha, although the authors did not differentiate between the two variants. Furthermore it is also possible that the activity of the central cortical areas, that is, the mu-rhythm, might have contributed to the spectral activity (8–12 Hz) measured in this study. Duntley et al.[10] have demonstrated the presence of mu-rhythm in REM sleep both in scalp and sub-dural EEG recordings by making use of the well-known reactivity of sleeping subjects to sensorimotor stimulation. This could be relevant for the interpretation of the results of Bértolo et al.[4] because central mu-rhythms are modulated by movement, most conspicuously of the hands. Indeed in certain kinds of dream states with tactile and kinesthetic components, as is mentioned by Bértolo et al.[4], modulations of mu-rhythms can occur. These would be reflected in EEG recordings, particularly those obtained from the central areas, as included in this study. This would be a confounding variable for Bértolo's interpretation because a change of EEG strength in the frequency range between 8–12 Hz cannot therefore be considered an unequivocal marker of activation of visual cortical areas, and thus of visual imagery.

Nevertheless, it is unlikely that this effect would influence the EEG recordings obtained from occipital areas, where Bértolo et al.[4] also obtained clear results. This issue merits further investigation using a more precise topographical analysis of the EEG features.

Looking for the underlying functional anatomy

Assuming that the changes of alpha activity associated with dreaming indicate the activation of visual cortical areas in congenitally blind subjects, a basic neurophysiological issue has to be raised. How can the activation of visual cortical areas in congenitally blind subjects be explained in terms of the functional anatomy of the brain? The paper by Bértolo et al.[4] does not give any indication about this issue, so we must look to studies performed using other brain imaging methodologies. In a PET study, Büchel et al.[11] demonstrated that congenitally blind subjects show task-specific activation of extrastriate visual cortical areas and parietal associations areas, although not of primary visual cortex, during Braille reading. This indicates the existence of crossmodal activation of extrastriate cortical areas by tactile stimulation in these subjects.

Early visual deprivation in monkeys results in the reorganization of occipital, extrastriate and parietal cortex, which is more pronounced in the extrastriate cortex than in primary visual cortex[12]. These experimental findings, along with those reported by Büchel et al.[11], indicate that the absence of visual stimulation in early development in congenitally blind subjects is likely to induce crossmodal reorganization of extrastriate cortical areas, but not of primary visual cortex. More specifically, another PET study[13] showed that subjects who became blind very early in life show activation foci in occipitotemporal and visual association cortical areas while performing a task of visual imagery (imagery of object shape) that is triggered auditorily. The results of these two PET studies[11,13] indicate that developmental crossmodal reorganization occurs in these subjects, thus allowing perceptual representations in the absence of vision.

To relate these PET findings to the EEG observations reported by Bertolo et al.[4] during visual dreaming, it is relevant to note that the cortical areas that showed the strongest activation during visual imagery in blind subjects[13] correspond rather closely to the areas where the main sources of visual alpha-rhythms are found in normal subjects[7].

How can visual imagery occur in subjects who never had visual experiences?

The third issue is a fundamental question of cognitive neuroscience. We have discussed already the anatomo–physiological substrate of how visual representations might be developed in the brain of congenitally blind subjects. In general, we may note that visual imagery and perception in normal subjects have common neural substrates[14–17] . Also, the activation of occipitotemporal cortex in congenitally blind subjects can be achieved by other sensory modalities, particularly by touch. The PET studies referred to above suggest that primary visual cortex would not be activated according to the above, but rather the extrastriate cortex. Indeed activation of primary visual cortex is not necessary to induce some coarse types of visual imagery[17] – those that are most likely correspond to the visual components of dreams in the blind subjects. These would consist of virtual images that are capable of being graphically represented (as in Fig. 1). Sensory modalities other than vision (tactile and auditory) can influence the functional development of the occipitotemporal visual system in the absence of visual stimulation in early life. In this respect the identification of particular sensory perceptions can be considered as a predetermined property of specific cortical areas. In the congenitally blind, interactions between non-visual systems with cortical areas that are predetermined to mediate visual perception are established by crossmodal expansion of non-visual inputs.

We can conclude from the study by Bértolo et al. that auditory and tactile inputs can create virtual images in the brains of congenitally blind subjects, as also found by De Volder et al.[13], which can be revealed in their dreams. It is important that further studies should clarify whether or not there is activation of other cortical areas during dreaming in blind subjects that might also contribute to alpha EEG activity. This might be done using spatio-temporal analysis coupled with the unequivocal identification of the corresponding brain sources. In this respect, a combination of whole-head EEG and fMRI, although technically complex, is likely to yield results that will be easier to interpret.

References

1 Kerr N.H. et al. (1982) The structure of laboratory dream reports in blind and sighted subjects. J. Nerv. Ment. Dis., 170:247-264.

2 Hurowitz C.S. et al. (1999) The dreams of blind men and women: a replication and extension of previous findings. Dreaming, 9:183-193.

3 Holzinger B. (2000) The dreams of the blind: considerations of the congenitally and adventitiously blind. J. Sleep Res., 9:Suppl. 1:83.

4 Bértolo H. et al. (2003) Visual dream content, graphical representation and EEG alpha activity in congenitally blind subjects. Cogn. Brain Res., 15:277-284.

5 Niedermeyer E. (1999) The normal EEG of the waking adult.
In: Niedermeyer E. and Lopes da Silva F.H. (Eds) Electroencephalography: Basic Principles, Clinical Applications and Related Fields. (pp. 149-173): Lippincott, Williams & Wilkins

6 Hall C.S. and Van de Castle R. (1966) The Content Analysis of Dreams.: Appleton-Century-Crofts

7 Manshanden I. et al. (2002) Source localization of MEG sleep spindles and the relation to sources of alpha band rhythms. Clin. Neurophysiol., 113:1937-1947.

8 Cantero J.L. et al. (2000) Spectral features of EEG alpha activity in human REM sleep: two variants with different functional roles? Sleep, 15:746-750.

9 Cantero J.L. et al. (2002) Human alpha oscillations in wakefulness, drowsiness period, and REM sleep: different electroencephalographic phenomena within the alpha band. Neurophysiol. Clin., 32:54-71.

10 Duntley S.P. et al. (2001) Characterization of the mu rhythm during rapid eye movement sleep. Clin. Neurophysiol., 112:528-531.

11 Büchel C. et al. (1998) Different activation patterns in the visual cortex of late and congenitally blind subjects. Brain, 121:409-419.

12 Rauschecker J.P. (1995) Compensatory plasticity and sensory substitution in the cerebral cortex. Trends Neurosci., 18:36-43.

13 De Volder A.G. et al. (2001) Auditory triggered mental imagery of shape involves visual association areas in early blind humans. NeuroImage, 14:129-139.

14 Kosslyn S.M. et al. (1993) Visual mental imagery activates topographically organized visual cortex: PET investigations. J. Cogn. Neurosci., 5:263-287.

15 Roland P.E. and Gulyas B. (1995) Visual memory, visual imagery and visual recognition of large field patterns by the human brain: functional anatomy by positron emission tomography. Cereb. Cortex, 1:79-93.

16 D'Esposito M. et al. (1997) A functional MRI study of mental imagery generation. Neurophsychologia, 35:724-730.

17 Kosslyn S.M. et al. (1997) Neural systems shared by visual imagery and visual perception: a positron emission tomography study. NeuroImage, 6:320-334.

[Jungliestner]

Who have been blind since they were fairly young :
They dream but what they see in their dreams depends on how much they could ever see in their life.
If someone has had a measure of sight, then that person dreams with that measure of sight
They dream as though they can see, colors included.

If someone has been totally blind since birth:
They can´t see anthing in their dreams
"They only have auditory dreams".

[sandcynch]

</span><blockquote><span class="smallfont">Quote:</span><hr size="1" />Originally Posted by (KaizerKa,)
Err, not be an arsehole but how are they going to read your post? O)o Although the idea IS an interesting one.<hr size="1" /></blockquote><span class='postcolor'>

I am reluctant to enter this post, since it has gone right down the toilet, but I can't resist! My cousin is married to a blind guy who runs a bed and breakfast and takes reservations online. In his spare time, he teaches a computer class for blind students at a college. Uh, technology--remember!

I'm sure he COULD answer such a question, but he'd probably not waste his God-given remaining senses on such childish potty-mouth. Really, if you guys were blind, would you appreciate the "crap" on this forum?

I would venture to guess that if someone had sight and lost it they could dream visually. Otherwise, I don't see how.

[Beavoid]

A blind person, forced to rely upon fewer senses can still model things he touches and hears and smells and compare them in his mind and 'eye' and create an image of what they 'look' like. Just as though you were blindfolded and then touched something. You can visualize it. Therefore, even an innately blind person should dream images and pictures and probably colors because it is his eyes that fail him, not his brain. The colors, however, would probably warped and incorrect. But who aree we to say? Oh well.

Seems logical to me anyway

B

[Plaything48]

Some of that's true, except we base our visualisation of objects on our own knowledge of what objects look like. A person born blind cannot visualise objects the same way we can.

[Milton Bradley]

My one blind friend reprts that he does not see things when he dreams.


P.S. He was blinded in an incubator after being born prematurely, and has never had vision.

[moondusk]

Interesting post, but I have no idea.

A person born blind and had recovered sight after an implant would have a good explanation to what he had experienced and what he sees now.

[Charcoal]

That'd be a very interesting thing to experience. Although the question has been answered various times, I found a link. It's not quite 100% credible, but they've got no reason to lie.
here

[Mr.Vicchio]

I read an article, where they gave a 30 something man his sight, he had never seen anything in his life prior to that. After about six months, they asked him to Draw what he saw. He drew a Bus, but only drew the front and back, the areas he could touch and knew whn blind. I wish I could find the damned article, but basically, YES there is a significant mental change for those that were born blind that are given sight, thier brians work real funny like.

[moondusk]

Originally posted by Mr.Vicchio, I read an article, where they gave a 30 something man his sight, he had never seen anything in his life prior to that. After about six months, they asked him to Draw what he saw. He drew a Bus, but only drew the front and back, the areas he could touch and knew whn blind. I wish I could find the damned article, but basically, YES there is a significant mental change for those that were born blind that are given sight, thier brians work real funny like.

You mean after having sight he dreams things, simillar to the way he felt when he was blind? It's kind of funny... Has he seen any dreams during the time he was blind?

[Deus]

From what I've read, the light most people "see" when they're dying is theoretically believed to be the synapses in the brain breaking ties and coming loose. So I would imagine even being blind, one would be able to "see" this light. In reply to another previous post just to add on to what was said, I also understand that many men blind from birth and are given sight due to technological advances have been known to either become depressed and even have the procedure reversed or commit suicide.

[Cadre]

Sight is in image of reality perceived through our eyes which collect light from the environment, resolve it into images, and then capture and forward those images to the brain. When we sleep our eyes are closed so we are simply visualizing a reality we are familiar with through sight.

How can they visualize in their dreams when they've never experienced sight before? Plainly, I believe they don't have the ability, however their dreams consist of interpretations of their reality through the available senses (auditory dreams, sense of smell is involved in the dream, etc, etc). Since the other senses are enhanced in the waking life it is a reasonable supposition that they are more potent in the dream state.

[Cadre]

Quote by: Deus I also understand that many men blind from birth and are given sight due to technological advances have been known to either become depressed and even have the procedure reversed or commit suicide.

Link to article or any resource? Sounds incredibly fascinating, would love to hear why professionals believe this to be so.

[blibbka]

I remember seeing a documentary about this (sorry, can't remember the title). The guy in the documentary got his sight back after being blind from (almost) birth, and then became very depressed.

I remember that one reason for this was that when he was blind - he was a blind person and fitted into that "disabled" group of society. Once his sight was back suddenly he was a "normal" person to the rest of the world: Except that in fact he was more confused now he had his sight than he had been when blind. Something to do with his identity chagning. Additionally he split up with his wife because he didn't find her attractive any more!

But I digress...

[Livemike]

Quote by: KaizerKa Err, not be an arsehole but how are they going to read your post? O)o Although the idea IS an interesting one.

There are devices that can transmit text information in Braile (there's one in the movie Sneakers). Presumably they can get information from a website and they can probably also transmit a monochrome image in Braille form too.

[L3T]

Our world exists due our input devices. Mostly namely our eyes, ears, smell, taste, ears, feel. Our most meaningful of (or to which we receive the most useful information of our world) is definetely sight/sound. We prioritize the most useful and harness each as needed (eating = mmmmm taste). Having all the senses to work with we gather our basic experiences as combination and memory stores them appropriately.
We are soooooo dependant and conscious of our looks etc. it is over commercialised for this reason: TV, movies, fashion, beauty, shape, form and most ironically: feng shui.
A movie is probably the most informative way we as humans have discovered to capture/simulate a human experience. My guess memory encodes this in the same way capture/encode different formats and compression in digital video.
My dreams ( as i recall) seem to be bizarre little movies that dont always correspond to an experience but they still appear in a "movie" type form. Yes there is also emotions too but that is a whole other area binded, but not altogether related.

Now consider a blind person. Their main input is sound/touch. In fact, their enhanced sensitivity to touch (using braille ) is by far their most powerful.They feel touch, shapes etc.They feel a bump or not. On or off. A biinary 1 or 0. And they get damm fast at processing these cos their brain CPU prioritises this function. THey do it so quick they dont have to stop and think about it much at all cos our brains are so intelligent it starts to find a a more effective/efficient/resource friendly way to do this. It creates what programmers like to call an algorithm. Basically they have translated the input (almost binary) into a meaningful picture in their mind. This "picture" has meaning to them cos using their other most valuable sense - sound they have been told or learnt to render/picture what the braillle is telling them.

The Analogy
A computer Video Card. The input is binary. In fact it is in many forms, just like a blind person. It has one input which it translates that to show on our computer screens. (Someone could explain to a blind person an object in much the same way).
The other inputs a video card has is for rendering and drawing shape form (polygons).
A blind person can receive the same instructions from braille and like a 3DFX chip their more sophisticated and continually evolving/improving algorithm does the translation.

So YES I believe they can "see" in their dream, but it is only what THEY SEE made up by the info they are fed by other people, touch, sound an braillle. SAYING that (and this is where I think it get heaps interesting), Why should they HAVE TO (or try to picture) what a the majority of us all actually observe? In a way society expects them to. The commercial and materialistic world we live in is at a point in the evoluttionary cycle where THIS IS HOW WE LIVE.
We go to the movies, we judge appearances, we enjoy beauty , value and appreciate (not always) aesthetics.

Blind people may not/ or dont have to attempt to experience the world OUR way. Their dreams may take on a form of teir own. A pattern of 1's and 0's may make them happy.
They say our dreams play out experiences that only act to balance our emotions. If we are lonely we will often dream that in our dreams all our friends are just following us around andwont go away, stuff like that...

The analogy above and the sci-fi ideas from movies like the "MATRIX" are actually closely related. In the Matrix the dudes are connected via wires (or a single digital binary connnection) and fed information simulating the info we gather using our senses. The "matrix" or dream world is basically all just a digital world made up of 1's and 0's. It was also controlled by the master programmer so its physics laws could suddenly change.
But of course if they just had a whole lot of 1's and 0's flying across across our TV screen i'm sure none of us woulod be too happy (unless yur "incredecode" a super-hero i made up just then). So they were nice enough to compile the matrix binary world back into 3D time and space so we could watch the movie.
I'm sure a braille version is out with the original binary form...
(plaese know i'm kiddin but do consider the concept)

hey this is my first post so plaese comment or send me an email...

[Lisastar]

Hi folks

I'm not blind but i have visual problems, blurring and double vision, but when i dream i don't have any of these visual problems.

I think it would be spectacular to be able to see what a blind person is perceiving in their dreams, and would answer a lot of questions about our perceptions based on our visual senses. We may discover they dream with colours we have never seen before.

A friend of mine see's blue where i see green and green where i see blue, red where i see orange and vice versa.

I have always had a problem with fainting in my life, when i come around i see everything in a black and white world, it takes a little time for my colour vision to come back, probably not very long, but it seems an eternity to me.

I dream both in black and white and colour.

Ive often wondered about these things too.

[Lisastar]

Forgot to say i have been meditating for years, and when i meditate it opens up infront of me like a movie screen and i have freeflowing pictures in colour. I learnt to manipulate colour beams as i began to learn about meditation. The meditations are different from my dreams, my dreams are always relevant to what is going on in my life and in colours that are familiar or in black and white. My meditations are always in living technicolour. I have mixed emotions in my dreams but not in meditations which are peaceful.

Have you read the book Idlewild, it deals with a lot of these questions. Basically it's about a virtual reality school...