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The Seventh Sense

Article #218 • Written by Zack Jordan

From childhood, we are taught that the human body has five senses. I'm sure we can all recite them: sight, hearing, touch, taste, and smell. This list has remained unchanged since the time of Aristotle. To most people, a "sixth sense" refers either to one outside the realm of the scientific, or one that simply does not exist in most humans.

However, ask a neurologist how many senses the human body has, and you might get a surprising answer. Many identify nine or more senses- some listing as many as twenty-one. The first category of senses is the "special" senses, including the familiar sight, hearing, taste, and smell. The second category is made up of the somatic senses, which we usually lump under "touch"- including our perception of pressure, heat, and pain. The third category, however, is not nearly as well-known. These are the interoceptive senses- those that deal with data originating in the body itself.

It is fairly obvious what happens to a person when a sense fails. Many members of society are missing one or more senses. It is common knowledge that blindness is the absence of sight. Deafness, of hearing. Everyone knows what it's like to lose taste and smell as well; this loss accompanies every head cold. But what happens when the body loses knowledge of itself is a far stranger occurrence.

The interoceptive senses are lumped together in various configurations, but there are basically three. The first-- balance-- is the sense of the body's alignment. This is the sense that keeps an animal upright; the famous ability of cats to always land on its feet, for example, is due to this sense. The organic sense is what alerts the body to its internal condition; this is how you know that you are hungry or thirsty. The third sense is known as proprioception. This, put simply, is the brain's knowledge of the relative positions of the body's parts.

To visualize this sense, close your eyes and extend your hand in a random direction. Now identify in your mind its exact position and open your eyes. Note that your brain was well aware of your hand's position, even though none of the "classic" five senses were currently detecting it. This is proprioception. If you want another example of this sense, try driving erratically enough to attract official attention. The familiar walk-the-line and finger-to-nose sobriety tests that you will be subjected to are yet more examples of what your body can do- or at least should be able to do- thanks to proprioception.

The loss of this ability is known by several names. Proprioception Deficit Disorder, Sacks' Syndrome, and Descartes' Disease are all titles for the same illness, which is a complete and total failure of the body's knowledge of itself. Since it is a rare disorder, it is difficult to say what the premonitory symptoms are. However, there have been reports that the first symptoms are extremely vivid dreams of lost motor function or physical control. These are followed by an increasing lack of coordination, culminating in full-blown proprioceptive failure. At this point, the human mind is completely unaware of its own body. Sufferers report a "disembodied" feeling, as if the mind and body have completely separated.

Oliver Sacks, one of the disease's namesakes, reported perhaps the first recognized case of the disorder. In The Disembodied Woman, he describes the process by which a patient- whom he calls "Christina"- succumbed to PDD. In a matter of days, she transitioned from a healthy and active mother of two to a helpless physical wreck, with no sensation of her own body. The preliminary testing showed that her nerves were in perfect working order; she could feel physical sensations nearly as well as she always had. However, somewhere between mind and body a roadblock had developed, preventing her brain from forming an accurate body image- or indeed a body image at all.

The results of this disorder are logical once one understands the concept of proprioception. Think of all the activities in a typical day that require the body's knowledge of its own position. If you carry your briefcase to the car while fumbling for the keys, your legs do not buckle because they are currently unsupervised. Your hand does not drop its load because you neglected for a moment to think, hold on to the briefcase. Your jaw does not hang slack because you weren't specifically concentrating on keeping your mouth closed. But for someone with PDD, these are exactly the type of things that happen.

Currently there is no known cure for PDD. Sometimes the body self-corrects, but in Christina's case it never did. Like any other sensory-deprived person, victims of PDD begin to naturally replace the missing sense with those that remain. Christina replaced it with sight. Since she no longer possessed an intuitive knowledge of where her respective body parts were located, she built up that knowledge herself using her eyes. If she wanted to pick up a cup of coffee, she watched her hand carefully until she had successfully put it down again. If she wanted to walk across the room, she had to supervise her feet until she was safely sitting on the other side. Sitting itself is difficult for a sufferer of PDD; if the hands are not watched carefully they will either grip the chair with white-knuckle intensity or release their hold, allowing the startled individual to slide to the floor.

In many respects, the body of a PDD victim becomes their puppet. Each movement must be carefully analyzed and put into motion; no longer can one trust the body to "just walk" or "just sit." Thus, the movement does not look at all natural; opening a door becomes a laborious process of extend hand, tighten each finger, rotate knob, extend arm, raise foot, lower foot, and so on. Meanwhile one must not become distracted from the other foot, and who knows what is happening with the body parts not directly involved in the current process.

Fortunately, PDD is an extremely rare disorder. It is neither contagious nor genetic, and no one knows what causes the permanent variety. There is a type that is brought on by massive overdoses of vitamin B6 (pyridoxine), but it is for the most part temporary with few lingering effects. A rather eerie set of statistics suggests that, unlike most disorders, the more education one has the more likely one is to develop the affliction. This factor, as well as the initial dream symptoms, suggests that the disease could have psychophysiologic roots. However, until we know for sure, this disorder represents one of the parts of the human mind that remains a mystery. It also proves with tragic clarity the old axiom: you never know what you have until you lose it.

Article written by Zack Jordan, published on 16 September 2006. Zack is a contributing editor for DamnInteresting.com.

Article design and artwork by Alan Bellows. Edited by Alan Bellows.
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59 Comments
Crispy
Posted 16 September 2006 at 06:57 pm

"A rather eerie set of statistics suggests that, unlike most disorders, the more education one has the more likely one is to develop the affliction. This factor, as well as the initial dream symptoms, suggests that the disease could have psychophysiologic roots."

Oh, thanks, so now I'm more likely to get it. :-(

DI!


debbiebf
Posted 16 September 2006 at 06:59 pm

Think how difficult it must be to eat or do common health and hygiene tasks. Did she also lose track of her ability to feel pain or sense where the pain was on her body?


Catkilller7
Posted 16 September 2006 at 07:24 pm

debbiebf said: "Did she also lose track of her ability to feel pain or sense where the pain was on her body?"

The preliminary testing showed that her nerves were in perfect working order; she could feel physical sensations nearly as well as she always had.


middlenamefrank
Posted 16 September 2006 at 07:49 pm

Crispy, I read once about "Med student syndrome", which is a condition where, whatever affliction the medical student is studying at the moment, (s)he'll tend to come down with the symptoms for. If (s)he's doing a paper on lower back pain, (s)he's likely to walk slowly and bent over for a while. (Pity the male med student who's doing a report on impotence!) Every human body constantly experiences twinges, minor aches and pains, small issues with functionality, and the more you pay attention to them, the more real they tend to be.

Debbie, the column says that the other senses are unaffected. No, she doesn't lose the ability to feel pain, nor to locate it. She just has a problem visualizing where her body parts are positioned in space at any moment. As an EE, if I built a robot, every joint would have a feedback device which would tell the central processor where that joint was located at any time. The central processor would give the command to flex the elbow, then monitor the feeback device to make sure the elbow went where it was told to go. If that sensor failed, the central processor would not be able to verify the orientation of that joint, unless there was another way to verify it (such as visually -- looking to see where the arm is located). If ALL the robot's position sensors failed, the robot would have a very difficult time functioning....the vision system would be overloaded trying to make up for the missing information for all of the sensors. This isn't unlikely, since (again speaking as an EE) I'd be likely to place all the position sensors on one bus (which could be shorted out at any point) or in series (like a JTAG bus) which can be 'open-circuited' at any point. A single systemic failure might make all of the sensors nonfunctional.

I'm taking this as (among other things) a lesson for us engineers. Critical information systems MUST be backed up. Vision systems need to be backed up by other systems (a blind person's ability to read is backed up by Braille; their navigation systems are backed up by dead reckoning, tactile feedback [a cane bouncing off objects] and maybe even echolocation). Tactile sensations (e.g. a person with leprosy losing his sense of feel) needs to be backed up by visual systems (VSE's). Helen Keller lost the two most critical senses (sight and hearing) and was able to function at such a high level she graduated from college magna cum laude and influenced the political scene of her time. The human body and mind are incredible models of redundancy and adaptability, us engineers need to aspire to their ability to function and even thrive under the most adverse of circumstances.


Shandooga
Posted 16 September 2006 at 08:36 pm

Damn, that was interesting. You never think of stuff like that.


another viewpoint
Posted 16 September 2006 at 08:44 pm

"In a matter of days, she transitioned from a healthy and active mother of two to a helpless physical wreck, with no sensation of her own body."

Was this an experiment? How does someone "succumb" at the moment they're being studied to prove a theorem? Were people/doctors sitting around trying to figure out a way to generate a case subject? There's something awfully screwy going on around here!

...then again, let's not forget the 8th sense...the sense of knowing when to shut up. Oops...guess I don't have that sense either! Drats.


HunterKiller_
Posted 16 September 2006 at 11:49 pm

I've never heard of this condition. I can't imagine how one in this state must feel... I wouldn't like to find out however.


HiEv
Posted 17 September 2006 at 12:15 am

another viewpoint said: ""In a matter of days, she transitioned from a healthy and active mother of two to a helpless physical wreck, with no sensation of her own body."


Was this an experiment? How does someone "succumb" at the moment they're being studied to prove a theorem? Were people/doctors sitting around trying to figure out a way to generate a case subject? There's something awfully screwy going on around here!"

No, it's just that she went to the hospital when her symptoms began, and while she stayed at the hospital her symptoms got worse and worse. She was being studied because this was happening to her, not the other way around.

The Man Who Mistook His Wife for a Hat is an excellent book, one of the few I've read more than once. There are tales of even more interesting psychological disorders in it than this one. I highly recommend it.


Drakvil
Posted 17 September 2006 at 01:20 am

It's a good thing this disorder is so rare. Of course, since they don't know what causes it they can't really rule out a genetic cause - it just might be extremely recessive (people that contract it would sure be less likely to survive to have descendants to pass it on). My first suspects, were I a practicing doctor, would be: a minor stroke, a viral or autoimmune disease that causes lesions in brain/nerve tissue (like AIDS, Alzheimers or multiple sclerosis), or a small but meaningful physical injury or allergic reaction that causes damage to the brain. Middlenamefrank pointed out that for the sense to fail for the entire body would indicate a failure in a bottleneck area of the sensory apparatus (the human body is known for doing an insane number of things in parallel - imagine if you had to concentrate on doing so in order to see or hear, or even make sense from your sense of touch) like the feedback bus on a robot. The way people are built, that would have to be in the brain.

In a different thread, it's interesting to think about treating this disorder (if we had the ability to do so) by inducing synesthesia - where the brain interprets one sense not only in its original context, but also by incorporating it into another (e.g. seeing colors when sounds are heard, but in a mental area that doesn't interfere with normal visual operation). I wonder how someone would "hear" or "taste" their body position?


Misfit
Posted 17 September 2006 at 01:27 am

HiEv, you beat me to it. *The Man who Mistook His Wife for a Hat* is a great book. Never finished it, but that was mostly a conflict of time. I couldn't stop thinking about it throughout this article. It was written by Oliver Sacks, too.

I wonder how difficult it must be to go to the bathroom.......... what an awful thought.
So, does this mean that all of her senses are fine, except for motor control? Is this stricly a muscle-to-brain thing? All other senses are perfectly fine?

By the way...
Good job, General!
Damn Interesting indeed!

I wonder how often victims of this carry around mirrors.


Marius
Posted 17 September 2006 at 04:07 am

Great! Now every time I do something typically clumsy I'm going to wonder if I am going to start dreaming about being a bus-shorted robot! What a bizarre, and tragic ailment. And, of course, a damned interesting article.


qhperson
Posted 17 September 2006 at 06:58 am

The problem with "The Man Who Mistook His Wife etc." is that it gives you so much more to worry about. Everyone should read it, maybe even be forced to read it, just for the sense of "there but for the grace of god go I."


denki
Posted 17 September 2006 at 07:55 am

I've had lots of dreams where I can't move my legs, where they become stubborn and unwilling, no matter how hard I try. These dreams are very scary, as it's one of those things where you really feel like you're there, and it seems I really can't move my legs. Or, if I can, it takes all my effort, and they are dogged and slow, as if they were both numb and had cement blocks tied to them.

And then, to my relief, I once was able to wake up while I was having one of these dreams to find that my cat was sleeping inbetween my legs, the covers under her in a manner where my legs were prevented from moving. Since I no longer live with my cat (I don't want to keep her indoors in my new apartment), I haven't had these dreams. It's eerie how the dreams reflected the condition of what my body was able or unable to do.

Off topic a bit, but meh. If you have dreams where your body isn't controllable, instead of hypochondriacly thinking you're coming down with Sacks' syndrome, just kick the cat out. Should work fine.


junebee
Posted 17 September 2006 at 10:18 am

I had the same dreams as Denki, and more than once. But those sorts of dreams don't seem quite relevant to this case.

In studies of psychology, the "med student symdrome" applies as well. Whatever chapter of about mental illness we're reading at the moment, we think we have that depressive disorder or whatever!


Misanthrope
Posted 17 September 2006 at 12:52 pm

debbiebf said: "Did she also lose track of her ability to feel pain or sense where the pain was on her body?"

Catkilller7 said: "The preliminary testing showed that her nerves were in perfect working order; she could feel physical sensations nearly as well as she always had."

That's only the answer to one of the questions debbiebf asked.

I'd be interested to know the answer to the second too - it does sound from the rest of the article like a sufferer would feel pain, but not be able to identify where it was without a visible clue, or trying to find it by subjecting various parts of the body to prodding to see if it got worse.


rhea_sun
Posted 17 September 2006 at 01:00 pm

Great article, Thanks Zack.

Damn Interesting if you ask me.


cornerpocket
Posted 17 September 2006 at 01:55 pm

I'd say Zack has the knack, but it rhymes and I would be likely disregarded as just another poetic hack (whoops, did it again). Anyway, I like the quality of his writing and the feeling that he is sharing and not trying to be erudite and ivy-towered. Plus, it was DamnInteresting to boot!!!


VarsityLens.com
Posted 17 September 2006 at 06:26 pm

Wow, this article really blew my mind! It's one of those things you take for granted growing up. Your teachers tell you you have 5 senses, so you take their word for it. Shows you how perfectly our world has been shaped for us as kids.

DISCOUNT CONTACT LENSES


Secret Ninja
Posted 17 September 2006 at 07:12 pm

LoL ^


etonalife
Posted 17 September 2006 at 08:00 pm

It's too bad one can't initiate this experience for only controlled momentary experiences. Terrible to think one has to spend the rest of their life like this. I'd certainly rather lose a limb instead. Perhaps one day this can be treated and destroyed like scurvy...


macfiend
Posted 17 September 2006 at 09:55 pm

It's funny they mention that symptom about vivid dreams. This reminds me of a condition I used to be commonly afflicted (only rarely now), called 'sleep paralysis disorder'. I'm not sure exactly how it works, but I do know it is very scary and intense at times (it can very well be life altering to some people). SPD involves complete temporary body paralysis, and extremely vivid dream states where the brain appears to be in a semi-conscious state.

When I experience this disorder personally, the first thing I try to do is to regain control of my limbs. In some cases I can see the actual room that I am in (usually the ceiling, or commonly, my alarm clock), and sometimes my eyes are closed and I 'see' what I 'see' while in a dream state: a vague scene of somewhere or something.

Anyway, to give you an idea of what it's like, try to imagine a nightmare that you have had where you seemed to 'consciously' will yourself awake (a sensation commonly depicted in movies - where you say to yourself: "wake up! wake up!"). It's the same thing when I try to will my limbs to move. Sometimes my limbs will jerk when I try to move them, and sometimes I will be stuck in paralysis for what seems like up to 30 minutes.

The first time I truly experienced this, I was about 13 years old - and the first thing I though to myself was "I'm being abducted by aliens" (it was a big phase for me as a young lad). Back then, I still didn't understand what exactly was happening to me (my parents didn't believe me), but years later I learned of SPD. SPD is the common answer to the question about cases of alien abductees (and possibly, for cases of religious experiences, angels and such), which is funny, because every time I experience SPD, it is never a pleasant experience - I experience the same fear sensation that I feel when having a nightmare. Not pleasant at all.

Luckily this doesn't happen so much any more, which is funny, because I swear I'm developing sleep-walking symptoms. I remember a case where I seemed to be sleep walking but in a semi-conscious state. I was witnessing myself doing some really stupid stuff which I had no control over - eventually I took control in the same way I take control when I am 'paralyzed'. Very freaky. Also, I've always seemed to have issues with my alarm clock mysteriously getting turned completely off without any recollection of myself doing so - I suspect that I am turning the alarm clock off in my sleep (I purposely place the alarm clock all the way across the room).


Drakvil
Posted 18 September 2006 at 12:06 am

denki said: "I've had lots of dreams where I can't move my legs, where they become stubborn and unwilling, no matter how hard I try. "

I read about something like this in the book "Why People Believe Strange Things". In the chapter on alien abduction the author detailed how there is a stage of sleep where the brain paralyzes the body so that when you are dreaming you don't start thrashing and moving around and possibly hurting yourself. When you are in this stage of sleep and your dream calls for you to do some moving around, if you are actually trying to move your body you encounter the paralysis and there are many people who interpret that as evidence of being abducted by aliens. I'm not saying that's what you experienced, but it sounds really damn close. I ran into this once as a child - in my dream I was at the airport at the baggage claim ramp and my toothbrush was coming down the ramp towards me, but I couldn't lift my arm to pick it up... I woke up after a half dozen panicked full-tilt attempts to move my arm, and my arm lifted up in the air as my eyes came open.

Does varsitylenses really think anyone is going to visit his site after crapping in the discussion here? If I knew where the store was physically located I would consider vandalizing it.


monorail
Posted 18 September 2006 at 01:12 am

Would your "sense" of fatigue be a sense?


denki
Posted 18 September 2006 at 01:39 am

How about "sense" of style? I know a few people that lack it...I'm sure we all know an aunt that lacks it.


DaveUlmer
Posted 18 September 2006 at 02:49 am

If you study Data Physics you will find that our universe presents 16 fundamental data types that our senses can pick up. Eyes detect three data types; Images, Color, and Motion. Our ability to detect motion is part of our Sense of Time. There are four types of temporal data. I'm always surprised that scientists always seem to ignore our Senses of Time.


gsd750
Posted 18 September 2006 at 04:08 am

I've seen something like this before explaining how the brain knows it's own spatial position - a 'body map'.
It was explaining why teenagers can be so clumsy, because as the body grows the mind map has to constantly adjust itself to new limb size etc.

For firsthand experience, as a motorcyclist, I find that when I get my gear on in the house before I go out, I'm always banging into the coffee table and other furniture with my knee-sliders etc., because they stick out another inch or so from my knee. If I don't specifically take extra care to avoid things then they'll get a wallop. Same as wearing a hard-hat on industrial sites, you're far more likely to bang your head on something because you forget you're a couple of inches 'taller'.

It's amazing how accurately we can navigate our bodies past obstacles with only millimetres to spare and not even realise it!


vallynmar
Posted 18 September 2006 at 05:34 am

I've known about these senses for a while. There is a book that talks about this stuff very well and in depth and it's about all three of the senses mentioned in this article. The book is called "The Out -of-Sync Child" (can't remember the author off the top of my head). When a child spins or rocks or swings or makes any repetetive "violent" (for lack of a better way to describe it) motion, they are trying to adjust their balance sense. When they can't sit with their feet on a floor and proceed to get fidgety it's because of the proprioception. They need to have their feet on somthing solid so they don't feel like they will fall off. It is very interesting. Any one that found this article interesting should read this book.

Damn iteresting as always Zack.


orc_jr
Posted 18 September 2006 at 05:35 am

DaveUlmer said: "If you study Data Physics you will find that our universe presents 16 fundamental data types that our senses can pick up. Eyes detect three data types; Images, Color, and Motion. Our ability to detect motion is part of our Sense of Time. There are four types of temporal data. I'm always surprised that scientists always seem to ignore our Senses of Time."

it sounds to me like the number of senses we have is largely a game of words. you can always find a way to further segregate data into more and more distinct types, such as image, color, and motion, but that doesn't change the fact that we "see" all of those. i have no problem with the idea of only the five "classical" senses. i suppose this proprioception might qualify as a sixth sense, but to me that's much like classifying "spirit" as an "element" in the same sense as fire, water, earth, air, etc.


didinskee
Posted 18 September 2006 at 10:22 am

I wonder if that samurai concept of "no mind" has anything to do with this... i remember it has something to do about executing an action without having to think about it.


cornerpocket
Posted 18 September 2006 at 11:02 am

MacFiend notes:

"SPD involves complete temporary body paralysis, and extremely vivid dream states where the brain appears to be in a semi-conscious state."

This is one of the symptoms of narcolepsy, although it is also an occasional experience in the public at large, often associated with sleeping after being REM-deprived. In the narcoleptic, sleep experiences that are normal in the deepest part of the sleep epoch migrate into other sleep stages such that they have sleep onset REM. In normal REM sleep, the body is in paralysis and the brain is quite active, all of this occuring unbeknownst to the sleeper since it generally occurs quite awhile after sleep has begun. When the person has sleep-onset REM, they are still wide enough awake to be alerted, or at least aware of the paralysis. This sleep-onset REM is unique to narcolepsy and is a dead giveaway. Then you have to spend a few thousand dollars for a '"sleep study" that demonstrates for the doctor that you aren't making it up just to get pescription amphetamines.


Josh Harding
Posted 18 September 2006 at 11:50 am

I worked for a while in a home for mental/physically handicapped people. One poor gentleman, had his "sense of thirst" off. A particular gland responsible for that information didn't work correctly so the guy thought he was thirsty constantly. Often, he would stand or sit with his head swiveling left to right, but when he saw a glass, cup, jug, or some other container that he identified as holding liquid, he would zone in on it and if unsupervised, would run to it and drink it...it didn't matter if it was water, stale soda pop, gasoline or liquid drano...he would drink it. A couple of guys decided to have some fun one night to see how much he would drink. He nearly died of hyperhydration.
One thing though, he never drank out of the toilet, or from the shower. For some reason, he never identified those things with drinkables.


circumstance
Posted 18 September 2006 at 11:54 am

I attended an Oliver Sacks lecture just the other day, and was reminded of how much I loved The Man Who Mistook His Wife For A Hat. Very interesting stuff, and Sacks is a genius.


FactWino
Posted 18 September 2006 at 02:48 pm

Drakvil sez: "It's a good thing this disorder is so rare. Of course, since they don't know what causes it they can't really rule out a genetic cause - it just might be extremely recessive (people that contract it would sure be less likely to survive to have descendants to pass it on). "

In order for that to be the case, it has to take effect early enough to prevent someone from having kids. In this instance, it was a mother of two, so if it is genetic, her kids already have whatever share of her genes they are going to get. The article doesn't give any kind of demographic data about who it affects. In fact, since it is very rare, there may not be any such data, so we don't know an average age of onset, gender differences, or anything else about those affected.

Damn interesting, I say.


wbeaty
Posted 18 September 2006 at 04:29 pm

Doesn't everyone get PPD once per year or so?

Whenever I wake up with a "dead arm;" when I've crushed my arm during sleep and temporarily cut off circulation, it has no feeling. But also, it has NO POSITION. I can use my other hand to open and close the "dead" fingers, move the forearm around, etc., yet I cannot sense any changes or sense its current position.

So, how many people here have experienced this "dead arm" effect? Think back and you'll recall that it wasn't just your tactile sense which was missing.


Drakvil
Posted 18 September 2006 at 04:42 pm

FactWino said: In order for that to be the case, it has to take effect early enough to prevent someone from having kids. In this instance, it was a mother of two, so if it is genetic, her kids already have whatever share of her genes they are going to get. The article doesn't give any kind of demographic data about who it affects. In fact, since it is very rare, there may not be any such data, so we don't know an average age of onset, gender differences, or anything else about those affected."

Good point. I guess the age at which you have children would also have bearing on it... more likely to be passed on if you have kids when you turn 18 than if you wait a sensible time until you are 30. Also, since this disorder is so rare, it's hard to develop meaningful conclusions from only 5 or so data points (arbitrary number used for illustrative purposes).


raksi
Posted 19 September 2006 at 12:51 am

This is my first post to Digg. I am very interested in the subject of "the other senses", and I believe New Scientist had a good article on this recently. I'll look it up. Most "sensation modes" are not regarded as senses because they seem to be purely internal, as well as subjective. The sense of body position is one of these. This is different to the sense we have of where we are in relation to gravity's pull, which is probably another "sense" entirely. Imagine yourself in a flotation tank. This is about as close most of of will get to the feeling of a being in micro gravity, and it is a lot more pleasant than a "vomit comet". You find that you can locate and move any part of your body from head to toes. A closely aligned "sense", not mentioned in the above, but arguably more complex, is the sense of unitary feeling. Interlink the fingers of both your hands and close your eyes. Logic would dictate that you feel sensations from the sides of all ten fingers, making a total of 20 separate sensations (!), yet we feel only a generalised single sensation. Indeed, we would be hopelessly confused if everything we touched was mentally processed and felt discretely. Having a mental "body map" is one thing. More astounding is that the mind can overrule the competing demands of the body map and combine many sensations into one. Two points about SLP and Dream Immobility follow.

Sleep Paralysis Disorder (SLP)

McFiend records his experiences with SLP, a term which makes this relatively harmless and surprisinlgly common effect sound much more threatening than it is. I first experienced it when I was 24, and only had it diagnosed 10 years later. I remember being paralysed and unable to make a sound, even when I was trying to call out to my girlfriend, asleep beside me on the bed. I often had frightening hallucinations of an intruder in the bedroom, stronger than dream images. My doctor said that this too was most common. From medieval times on people have imagined witches in their room, and sometimes they would sit on the victim's chest! This must be the genesis of the "abduction theories". The cause, it was explained to me, was simply that sometimes, for some people, the wake up instruction list (if you can imagine a computer booting up) becomes slightly out of order, and the conscious mind becomes active *before* the instructions necessary for somatic control are processed. The mind interprets this as paralysis. I noticed too that I was more likely to experience an episode if I had been smoking just prior to sleeping. After I gave up cigarettes 10 years ago (and I was a heavy smoker) I never had a recurrence, so perhaps there are physiological triggers for SPD as well (heavy smoking and drinking).

Can't Run in Dreams, just when you have to. (MY NEW THEORY!!)

Denki records his experiences with this dream syndrome, one that is so common that just about everyone has experienced it. Typically, something nasty is chasing you, and yet you can hardly move your legs as you try to run for your life. The result is feelings of fear and panic, similar to those in movies where goodies are running from the zombies, only to stumble, get caught up in fencing wire etc. Now, I don't know if this is the right place to make this public, but for some years now I have had a theory about why this happens, one which I have never seen in print (although that does not mean it is not there somewhere). What do you think?

In dream narratives, the story does not proceed in real-time. If in a dream you have to wait for an hour in a doctor's waiting room, your dream will quickly fill up that time with other events. In other words, dream narrative proceeds much like the narrative of a movie or TV show. What is inessential to the plot is cut out or minimised. In fact dreams are so like stories we tell to each other that I think that perhaps dreams are the progenitor of creative story-telling. So dream-time works like story time, roughly lasting as long as it might take for you to tell the story. That means dreams *compress* time, like narrative usually does. But there are times when this natural order is turned on its head. Sometimes, it takes *longer* to tell about an event than the event would take to run in real time. Think again now of that terrible chase dream where you can't move your legs. My theory is that you are trying to tell the story in usual dream time. Except that here, the events of what might realistically be a few seconds have crammed into them all sorts of important details each of which might only take a split-second, (how you slipped, what the zombie looked like, where you decided to go etc). In consequence, it takes much longer for the brain to "tell" itself this, than it would to actually just act it out. So in such a case, the action is not speeded up as is usually the case, but slowed down (in order to accommodate all this critical detail). But the "flight to survive" instinct in humans is understandably intense, so the part of your brain that is immersed in the action is screaming: "What the hell's going on!!??!! Get the HELL out of there!!" And it interprets the slow-down as some catastrophic failure of your body, or the presence of some kind of gooey mud or the like dragging on your feet.

I have another theory on why so many of us have had dreams of flight. Why do you think this happens? If anyone is interested, I'll post them my views.


Bibliophile
Posted 19 September 2006 at 06:29 am

People with dispraxia have a similar but not so extream version, some dyspraxic's brains have difficulty tell exactly where it is in space and so often they are clumsy because their bodies guess and when they get it wrong they look like they are clumsy. I have this problem and my body seems to have a stange affinity for walking into doorways!

Anyhoo damn interesting article


openside
Posted 19 September 2006 at 08:43 pm

raksi said: "This is my first post to Digg.

Well don't hold back. :-)


Drakvil
Posted 20 September 2006 at 02:48 pm

raksi said: "This is my first post to Digg."

I guess he has a little confusion between this site and the one that provided him the link to get here.... Not that I'm complaining, I wouldn't have found this site without Digg. And now everyone here loves me! >:)


anna k
Posted 20 September 2006 at 03:18 pm

ONE thing in that description caught my eye, and that was the part about jaws going slack while concentrating on something else.

Anyone else do that? Man, I hate that! I swear if my brain's over-occupied, I could probably start drooling.


cornerpocket
Posted 20 September 2006 at 05:40 pm

FactWino and Drakvil please take note: The Darwin Awards can go out to those who are past the child bearing age since the concept of Survival of the Fittest includes the notion that child-rearing is as important as child-bearing...at least in pre-civilization times. If one is ill-suited to one's environment, even if that person manages to have children those children will perish if said person cannot cut the mustard long enough to help the offspring reach childbearing age. Even grandparenting can be a part of preserving the gene pool. Weak links can ball up the works for several generations, even to the point of terminating the entire branch of the tree.


myles325
Posted 23 September 2006 at 06:22 am

New Scientist has an excellent article on how many senses humans might have in its 29 Jan 2005 edition, page 34, which can be read online by paid-up subscribers. It should be apparent today that the division of our sense contact with the world into 5 senses is a very ancient one, and in need of a good overhaul. Animals certainly have other senses humans don't. For example manta rays and even the supposedly primitive platypus have systems where they project an ambient electric field. When a creature passes thru this, it sets up magnetic impulses and alerts the manta or platypus that prey may be nearby. This means it can find food at night, or when the water is hopelessly muddied.

One of the defining characteristics of a "sense" is that it should be objective (not an imaginary thing) and tell us something real about the outside world. So quite a few candidate senses get excluded on these criteria, most obviously that of pain. But even conservatives should be able to accept the ability to sense heat and cold as a genuine sense. They are traditionally included with those of touch, but this is manifestly wrong. Just because it largely operates thru the skin should not mean that all such sensations should be lumped together. We now know that completely different types receptor cells work for heat and cold sense, and that termperature is not, as the ancients might have thought, a property of an object in the same way as texture.

Here are some points from the New Scientist article.

VISION - conservatives count as one sense only. Most others split this into Light and Colour. Radicals include the 3 primary colours red, green and blue.

HEARING is in NS only one sense. Though I would include pitch sense, as tone-deafness is well known.

SMELL is in NS only one sense

TASTE is according to conservatives only one sense. Others include the traditional four variants of sweet, sour, bitter and Salty. Radicals include the "newly discovered" sense of "umami", a sort of savoury meat taste, found in full cream milk, liver and others

TOUCH is only one sense to coservatives, but radicals accept light touch and pressure as 2 others

PAIN is accepted as a sense by radicals, who divide it into cutaneous, somatic and visceral

MECHANORECEPTION has a number of variants which are accepted by some or other groups. They include balance, rotational acceleration, linear acceleration, joint positions (discussed in this thread), kinaesthesis (the ability to sense movements of limbs and body), and muscle stretching sensations.

TEMPERATURE sense is generally accepted as a genuine sense, even by most conservatives.

INTROCEPTORS These are senses to do with blood pressure and so on.

For myself, I believe that there are more than 5 genuine senses, and while definitions are crucial here it is not just a matter of semantics. Even if a lot of sensations are not genuine senses, it would still be a good idea to list and describe them. What do you make of motion sickness for example. This is not a sense as such, but it is not pain either. As anyone who has had a severe dose of it knows, it can be rather worse than most kinds of pain. There are many others.


R Y A N
Posted 19 October 2006 at 08:40 pm

Wow! thank you for typing this.. I'm always interested about things that humans can do.. especially senses.. I've been exercising my hearing lately by listening to everything possible to hear (even the static noise that goes on inside my head) and would work on balancing but never thought of it as a sense. Wow 21 senses.. most likely more.. Thank you for typing this.


R Y A N
Posted 19 October 2006 at 08:53 pm

I just read myles325's post.. In reply.. Most people tend to ignore true definitions of words and why things were called what and why. (why senses were called senses and why they were called senses). If anyone would read their dictionaries they'll find "1. any of the faculties, as sight, hearing, smell, taste, or touch, by which humans and animals PERCEIVE STIMULI originating from outside or inside the body.". What is a stimuli? again the dictionary "1. Something causing or regarded as causing a response.". We could catagorize millions and billions of different senses humans and animals (plant life included) have, but the important thing to remember is that not everything can be defined by words, especially in America (ugh everyone claims to have their own way of understanding things). Anyways thanks for being thoughtful.


stoid7
Posted 15 November 2006 at 02:15 am

im not saying i have this, cus i know i dont. ehers a quote from the article "Your hand does not drop its load because you neglected for a moment to think, hold on to the briefcase. Your jaw does not hang slack because you weren't specifically concentrating on keeping your mouth closed. But for someone with PDD, these are exactly the type of things that happen.". my jaw actually does hang slack if i dont pay attention to it,. just thought id throw that out there


V-Blue
Posted 08 January 2007 at 04:18 am

hmmmmm.......DaveUlmer made an interesting point- sense of time. does it classify as a sense at all?and if yes, why do we ignore it?


Starling
Posted 10 February 2007 at 09:08 am

anna k said: "ONE thing in that description caught my eye, and that was the part about jaws going slack while concentrating on something else.


Anyone else do that? Man, I hate that! I swear if my brain's over-occupied, I could probably start drooling."

Goodness! *slams mouth shut* This happens to me every time I go on the computer and start reading something (like, say, a Damn Interesting article...)

Oh, and has anyone else read Douglas Adams? Dirk Gently believes he has eleven senses. What could they be, I wonder? Sense of time,(thank-you, DaveUlmer) sense of danger, common sense...


ifeelya
Posted 06 March 2007 at 03:54 am

As ever, gotta slam the psychobabble theory. Once you look at some functional brain scans, you start seeing how "intelligent" and "educated" are very broad terms that don't really say much. Did the lady read a lot, or have a career in rocket science, or something? What does that mean? If you're less-educated, maybe people just assume you're crazy or mentally retarded and leave it at that.

Anyway, I think it must have something to do with the way the brain processes signals from the inner ear, amongst other things. For example - skaters and dancers learn to spin by tricking and overriding the brain's sense of proprioception. The brain thinks you will fall down. You disagree and spin anyway. If that neuronal pathway fails, then maybe you'd be like this woman. It might be a trainable perception in both directions? That would be...damn interesting?


pegleg
Posted 05 April 2007 at 03:54 pm

BBC radio 4 did 5 short programs on extra senses (pain, balance, time, temperature & digestion) which you can listen to on the website, they talk about some of the topic mentioned in the discussion.


aimew
Posted 28 July 2007 at 02:05 pm

This seemed an odd post in relation to others that I've read here. It started out as a description of senses and sub-senses (pressure, temperature, etc. being part of touch, etc.) and went on to mention interoceptive senses (as opposed to physical senses); but then it seemed to wander off into a detailed description of a disorder of one of these interoceptive senses.

Were all of those 'debatable' senses covered? That is, were the three interoceptive senses, along with the main five physical senses, all that are recognized at this time; or are there others as well? If so, that would be eight but nine were mentioned in one place, what was the ninth? Perhaps my confusion on this issue is in how they were stated (and counted in the article); Wikipedia has them sorted out a bit clearer in their article on the senses (http://en.wikipedia.org/wiki/Senses) and it and this do seem to mention nine.

Then, however, there was a reference to as many as twenty-one senses that are recognized by neurologists, but what are they? The Wikipedia article mentions several (but not twelve) in the area of intelligence; are the missing dozen all in that category?

This article is Damned Interesting and I suppose that's why I feel frustrated with being teased with a reference to twenty-one senses but then not saying what twelve of them are. It is keeping me busy, though, so it has peeked my interest - ultimately, that is the point, isn't it? (I still can't find twenty-one listed anywhere, however.)

Thank you...


jwasko
Posted 23 September 2007 at 09:04 am

physiographic
Well, if someone here is simple doing clinical research, I can tell you that physiographic meds play no effect on these symptoms, thus meaning future research into the higher and lower brain functions are needed. It is NOT clinical depression. Maybe you should Google the word "VEDA".

I have all the above systems, I call tell you this, it is a tough way to live, it robs you of your career, it will financially destroy you (thanks bush) and you basically live in my own mind trapped. It is like fixing a computer that gives you different errors all the time. This leads us to fluid viral or nerve damage.

P.S. - quit calling us "case studies" - we are already defeated, no need to rub it in.

Personal Quote: As the world turns around you, you realize after a decade or so that this is a life in hell. It absolutely will not stop under any circumstances until you are dead - every day brings something new that you never tell any one about, it is a fight, make no mistake about it, knowing who or what you are fighting is a good start..

JJ


HiEv
Posted 25 September 2007 at 04:33 pm

ifeelya said: "As ever, gotta slam the psychobabble theory. Once you look at some functional brain scans, you start seeing how "intelligent" and "educated" are very broad terms that don't really say much."

Of course they do. "Intelligence" is your ability to learn, understand, and reason. "Education" is the amount and quality of schooling you've had in one or more areas. And what do functional brain scans have to do with it? Functional brain scans can't detect either particularly well because they aren't something so simple or obvious in the way the brain physically functions that they can be measured by that means.

ifeelya said: "Did the lady read a lot, or have a career in rocket science, or something? What does that mean? If you're less-educated, maybe people just assume you're crazy or mentally retarded and leave it at that."

Uh... Huh? Are you trying to say that doctors looking at a set of symptoms like "I don't know where my limbs are" they'll blow it off as stupidity if they somehow magically know the person isn't well educated? That's just ridiculous. The diagnosis is dependant on the symptoms, not the education of the patient.

ifeelya said: "Anyway, I think it must have something to do with the way the brain processes signals from the inner ear, amongst other things. For example - skaters and dancers learn to spin by tricking and overriding the brain's sense of proprioception. The brain thinks you will fall down. You disagree and spin anyway. If that neuronal pathway fails, then maybe you'd be like this woman. It might be a trainable perception in both directions? That would be…damn interesting?"

Uh, no. That's just "psychobabble," as you put it earlier. You are confusing a sense of balance, which comes from a combination of sight, proprioception, and the inner ear, with the ability to know where your body parts are. You can reach behind your back and scratch that itch without looking because of proprioception; your inner ear and sense of balance have nothing to do with that.

So, skaters and dancers aren't "overriding the brain's sense of proprioception," they're simply trained to override reflexes people normally have to keep them from harm. To do that they need a lot of practice and an excellent sense of both proprioception and balance.


God
Posted 11 November 2007 at 06:09 pm

DI..................


somethingawful
Posted 29 June 2008 at 02:14 pm

fashion sense?


siphons
Posted 23 April 2009 at 12:20 pm

Drakvil said: "Good point. I guess the age at which you have children would also have bearing on it… more likely to be passed on if you have kids when you turn 18 than if you wait a sensible time until you are 30. Also, since this disorder is so rare, it's hard to develop meaningful conclusions from only 5 or so data points (arbitrary number used for illustrative purposes)."

I agree it's more sensible to have children at 30, but biologically the older the eggs are, the higher the likelihood is for defects. You're much more likely to produce perfectly healthy children at 18.


siouija
Posted 13 July 2009 at 08:31 pm

Crispy said: ""A rather eerie set of statistics suggests that, unlike most disorders, the more education one has the more likely one is to develop the affliction. This factor, as well as the initial dream symptoms, suggests that the disease could have psychophysiologic roots."

Oh, thanks, so now I'm more likely to get it. :-(

DI!"

I have a stress disorder that I believe is known as 'Alopecia'; where you lose hair in patches. Some attribute it to another disorder called 'Sleep Apnea', which is where you lose or hold your breath either momentarily or extensively while sleeping. Often times this occurs once REM (rapid eye movement) sleep begins and can last until the person is awakened by shortness of breath or extreme numbness, again due to physical and/or psychophysiological stress, or other factors such as smoking.
While experiencing lucid or non-lucid dreams during the REM stage, and therefore also during ensuing fits of Apnea, the brain may become deprived of oxygen in specific zones and lose the aforementioned 'bond' with the corresponding muscle or organ, causing regions of blood vessels and hair follicles to stop functioning, hence the Alopecia; or as is correlative with 'Proprioceptive deficiency'.
It must follow also that, those dreams experienced during such a state are usually based on a loss of motor skills or any other type of similar loss of mental to physical control and correlate directly to symptomatic occurrences such as the development of any type of 'Proprioceptive Deficiencies'.
Also when experiencing lucid dreams while in such a state, the dreamer loses the capability to control parts or the whole of his or her 'dream' body in that, it could possibly serve as a means of symptomatic predication of any developing 'Proprioceptive Deficiency' or other bodily affliction. (Dream Theory for another bright day)

It is purported in this article entitled "The Seventh Sense" by "Zack Jordan" that these disorders could possibly have psychophysiological roots (and also the extent of one's knowledge on the subject could lead them to subconsciously 'will' themselves to contract such a disorder). These are Damn Interesting grounds for future exploration on the topic and, naturally, make me a viable candidate to contract such a disorder.

Please Note: I have not done any manual research on this topic and have written this comment only out of memory and if I may be wrong about any particular section, I shall be appropriately and formally corrected.

These comments may be taken as mere speculation, since there is no research I am aware of which may prove any of this to be true or untrue, and could also potentially rob some of my credibility. Especially because of the fact that when I (personally)
have encountered Sleep Apnea and Alopecia I also experienced such dreams and often found myself waking in fright, unable to breathe, as well as unable to move certain parts of my body. Damn Interestingly enough, however, I was always acutely aware of the afflicted limbs and their respective location and position in space upon finding myself unable to move or operate said body parts (including automatically operated organs such as the lungs). Only the 'bond' between thought process and action was absent.

macfiend said: "It's funny they mention that symptom about vivid dreams. This reminds me of a condition I used to be commonly afflicted (only rarely now), called 'sleep paralysis disorder'. I'm not sure exactly how it works"

These two points could be closely tied together somewhere along the line.


RoxieRose
Posted 07 August 2012 at 01:14 pm

I was diagnosed with this as a child. I was constantly getting injured while doing simple things such as walking. One time I actually dislocated and broke my big toe while walking across a room where the floor was clear so there was nothing to trip over or stub my toe on. I've also twisted and sprained my ankles and knees more times to count, including one time yesterday and once this afternoon, again just walking. I also have a problem walking into door jams and falling down stairs. The vivid dreams I had did not seem like sleep paralisis because in my dreams I could move my limbs but they never did what I wanted them to. Also, every time I pick up or put down a glass I have to watch my hand the whole time to make sure I don't miss the glass and knock it over or so I don't miss the table when putting the glass back down. I often have a hard time sitting down in chairs I am not familiar with. Whenever I use a public restroom I have to use the handicapped stalls so I can hold onto the rails to prevent myself from falling while trying to sit down. I wish doctors knew more about this disorder, it would be nice to know if there was anything I could do to make it better. I also wish more people were aware of it because it seems like whenever I fall or walk into something in public people assume I am drunk or something.


Spot
Posted 16 January 2014 at 11:00 pm

COMMON sense ? Somewhere.


Ashley Schwenkel
Posted 04 April 2014 at 02:48 pm

It probably has a lot to do with the cerebral cortex. The part of the brain that controls all bodily functions, movements, responses and reactions. As well as with the conscious and unconscious mind. Frequency rates of meditation and of thoughts probably also have a lot to do with this, as well. Very interesting, but it seems as if there are definitely more than one explanation to this disorder or symptom. With all of the different categories of the brain, and how they react and connect to all other bodily functions, anything can be detected, and found back to its roots. The root of the problem or issue, that is. This is what is so amazing to the human body. And just life in general, itself.

Ashley Schwenkel
22 year old female


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