Author Topic: OK NEUROLOGISTS: You're up for a question re: Visual 'Phantom Limb' phenomina  (Read 1061 times)

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Online RJHayward

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Been seeing these visual 'side effects' or mild illusions, since I was a kid... What are those vague shadow shapes, that often will move in near synchronous, with my hand motions?
   Eyes closed, with hand behind a board, or placed under the table, it's as if an X-ray vision lets me 'see', in a crude cartoonist sense, an approximate view (actual hand is often displaced a lot from the 'shadowy' view.

   It reminded me, of descriptions of 'PHANTOM LIMB', where a person has a sense and feeling, in a limb that was injured / removed. So the theory here, is that an effect, while concealing (the waving hand / arm) is somehow producing a likeness, of the limb and motion, in a crude approximation to what the actual scene looks like.

   In my picture, I placed an ordinary sock, to show, approx, how this 'looks', keeping in mind that the eyes are closed, hand would be under a table or behind something. Of course, this is not an actual shadow of my hand, and no bright lights are there creating shadows...
   I just think that 'Visual Phantom Limb' is a pretty good explanation, especially with no alcohol use or mental illness (girlfriend might argue that).
I spoke with one Optometrist, briefly, who tended to agree, I don't have the (medical) expertise to explain / interpret that ( harmless) visual experience!
 

Offline DrG

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Been seeing these visual 'side effects' or mild illusions, since I was a kid... What are those vague shadow shapes, that often will move in near synchronous, with my hand motions?
   Eyes closed, with hand behind a board, or placed under the table, it's as if an X-ray vision lets me 'see', in a crude cartoonist sense, an approximate view (actual hand is often displaced a lot from the 'shadowy' view.

   It reminded me, of descriptions of 'PHANTOM LIMB', where a person has a sense and feeling, in a limb that was injured / removed. So the theory here, is that an effect, while concealing (the waving hand / arm) is somehow producing a likeness, of the limb and motion, in a crude approximation to what the actual scene looks like.

   In my picture, I placed an ordinary sock, to show, approx, how this 'looks', keeping in mind that the eyes are closed, hand would be under a table or behind something. Of course, this is not an actual shadow of my hand, and no bright lights are there creating shadows...
   I just think that 'Visual Phantom Limb' is a pretty good explanation, especially with no alcohol use or mental illness (girlfriend might argue that).
I spoke with one Optometrist, briefly, who tended to agree, I don't have the (medical) expertise to explain / interpret that ( harmless) visual experience!

It is not clear to me and I am not a Neurologist, but....

"Been seeing these visual 'side effects' or mild illusions, since I was a kid... What are those vague shadow shapes, that often will move in near synchronous, with my hand motions?"

What you are describing above sounds like Illusory palinopsia https://en.wikipedia.org/wiki/Illusory_palinopsia - something like a brief after image that is following the motion. Note that it can be idiopathic.

If you're describing seeing something like that (an image) when moving your hand behind an opaque barrier is something else and I am not really sure what you are talking about. There is a known "touch" illusion that is sometimes called the magnetic touch illusion in which you experience  some kind of tactile input because of visual information that "creates" an expectation" - https://www.sciencedirect.com/science/article/pii/S0010027716301512 and https://www.researchgate.net/publication/309039503_Commentary_The_magnetic_touch_illusion_A_perceptual_correlate_of_visuo-tactile_integration_in_peripersonal_space

The phenomenon is roughly illustrated in this video


Phantom limb phenomena are not directly related in my opinion, but may have some common characteristics in the sense of some kind of "neuronal expectation" leading to the perception phenomena, i.e., there is real neural activity produced as though it originated in the phantom limb. https://en.wikipedia.org/wiki/Phantom_limb

BTW: The technology of the nervous system, when undamaged, is never "dodgy technology" (Re: this sub-forum) - it is imperfect, but, for what it is designed to do, the programming is much better than anything else I know about. :)
- Invest in science - it pays big dividends. -
 

Online RJHayward

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Thank you, Dr G. for your summaries.
   There is more info, but as an EE with very little medical / biological expertise it can be a challenge.
Seemingly unrelated, is (my) study of AI and image recognition, but it looks, more and more, like the medical and neurological sciences have much much more to offer. So I've been trying to do some more study, including basic engineering subjects, like matrix math and convolution. (The FSD or fully self driving Tesla system has a great video coverage, see the ',General Chat thread).

  Another human visual related aspect involves pulse propagation networks, having large arrays of 'sensitive' gates. Thanks again, DrG for some of that terminology used, regarding normal/abnormal situations in neurology.
   AND, (LOL), now I can, at least spell 'phenomena' now.
   Us engineers: we need the input from neurologists and other functional bio-sciences, if to make some decent progress in the future!
 

Online RJHayward

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So, I have posted under 'dodgy topic' due to the appearance, initially, of straying from purely electronics related, while vision related topics and neurology science seems, to me, to be more accurately described as 'PULSE OPERATED' systems study. That leaves enough wiggle room, to widen the subject/topic.

   Consider this 'system':
Suppose you take a big shallow box, full of set mouse-traps, each having a ping pong ball set on top. Now, this classic demo will have a predictable result; if a single ball is dropped down into the box having 50 set mouse traps, some sort of chaos will occur, a chain reaction will propagate thru, untill all or most traps have sprung.
   For that demo system, you could 'tune' your response, for example you could set up just barely enough (set traps w ball) so that the chain reaction just barely catches, (or just stops early).
   Believe it or not, these sorts of 'impulse' reaction systems have commonality with vision and retina response.
   Here are some questions coming up regarding pulse response arrays, and the hand movement results I am getting:
  For the coordinated motion, I could imagine doing experiments, measuring nerve signals in the hand. However, making (nerve electric) measurements of eye and retina activity is a bit obscure! Plus, those perceptions of activity might not even involve the eye directly, so any experiment to measure these movements or illusory perception, well, that sort of testing is way beyond my skill set.
But if you could, the idea is to try to corelate hand movement, direction of motion etc with the perception (leaving the subject's personal interpretation out of it).
  Now, as to any 'mapping', there seems to be lots of rotational translations, where a linear movement causes a response (in this hypothetical experiment setup) where subsequent pulse movement or migration of pulse groups, becomes mapped into a rotation progress, rather than simple straight line paths.
Sorry to be, maybe, too obscure, but mainly questions about vision and use of pulse response in a matrix (of mapped gates).
...more later, thanks
 

Offline DrG

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I'm not sure what you are after. It sounds like you want to be able to measure a neuronal correlate for the afterimage you experience when you wave your hand. Is that close?

I also do not understand exactly what is meant by "pulse response arrays". I did search and saw a bunch of hits - radar and other things and I just don't have a good feel for that. Pulse propagation networks is a very old neural network model/concept https://www.brainfacts.org/thinking-sensing-and-behaving/vision/2012/vision-processing-information that I vaguely recall.

I admire your willingness to think about the issues and to ask questions, but there is a lot of background to understand before you can, even mentally, devise experiments that would make sense. Here is the deal bluntly and I really hope you are not offended because I mean no offense.

I feel like I have been down this road many times with many "EEs". That may be unfair stereotyping on my part, but the typical EE curricula for a 4 year degree likely does not include much physiology, sensation and perception, learning theory, or general neurobiology or neuroscience. Yet all of that is terribly important to having a foundation to even grasp at a speculation. To be sure, I have known some very sharp biomedical engineers with advanced degrees and who have studied these topics in depth - it is not out of the realm of engineers (or anybody else), I am not saying that at all. I am saying that it is specialized and it is complicated and it looks like we don't yet know as much as we don't know.

I have been annoyed for years that a group co-opted neuronal terminology and have given us the new and improved "deep learning" (aka classifying things). I know something about neurons, not everything, but something about them, and I say that those ain't neurons and I don't see the value in sharing the terminology to suggest that they are neurons. I may be a bit biased :)

A typical (and terribly frustrating)  level of understanding of how we "see" starts and functionally stops, at light hitting the retina. I am telling you that you do not need any light hitting a retina to report "seeing". This has been demonstrated often. You "see" while dreaming but your eyes are closed. Some musicians "see" the color of music - no relevant retinal information is needed. Hallucinogenic drugs are named as such for a reason. I promise you that I (well someone) could stick some electrodes in your brain and get you to "see".

Look at the typical mickey-mouse diagram of the visual system: [https://www.brainfacts.org/thinking-sensing-and-behaving/vision/2012/vision-processing-information]



Where do you think "seeing" is located in that diagram?

In fact, I would argue that no two people could EVER see the same thing - it is impossible because 1) they can't occupy the same space and 2), which is much more important, no two people have exactly the same genetic+developmental+experiential makeup that could possibly lead to an identically functioning visual cortex (and other parts). One typical problem is that folks want to concentrate on the transducer (eye) because it is so much simpler than the rest, but that does not mean that the retina is the most important part.

I saw this the other day (I can't remember where or I would give the cite, my apologies to the author) and, apart from ignoring the inconvenient bit about "all things being equal", I thought it was so funny that I saved a copy.



So, I probably can't be of much help because I don't understand what you trying to do, but again, no offense intended. Hopefully, I have been, at least, mildly entertaining :)

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Online RJHayward

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Thank you, Drg, I like a bit of honest criticism. I often operate in thinking as an inventor: Lots of (seemingly) unrelated subjects, winding together to see some novel results. Then, with maybe some luck, get some results that can benefit some larger groups of folks.
   That sort of thinking / speculation is the form that an inventor takes... Think about what a BOSS somewhere might say:
   "Newton...We need a new approach, for freight train tracking. None of this old manual tracking rubbish...
We need a 'radar' or some kind of vision machine, for tracking these (moving freight cars)."

  In this instance, I have that similar, open questions approach, although right now my focus is on Tesla, and the FSD concepts (fully self-driving). The concepts being outlined there are a challenge, and I don't fear new things, in technology and science.
   If you want some more 'flavoring' on this sort of inventor / speculation on novel things, please see
GOOGLE PATENTS 'Richard Henry Bastian'
...that's got some wild-ass ideas there. Sadly, many inventors don't get immediate success; That comes with the landscape. (I actually just call myself an 'Inventor', for now. Makes for good bar'chat...(not).
 

Offline Stuart Coyle

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Not a neurologist, but I am on the autism spectrum. As I have discovered through learning about my condition, there are many strange sensory issues that some people have that others do not experience. It sounds like your experience is like some sort of synathsesia, where stimulation of one sense causes a different associated sensation, in this case proprioception causing visual sensation. For me, sound causes some visual stimulus.
 

Online RJHayward

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Thanks Stuart, for reply.
   One theory as to tracking hand position, speed and direction, during movement isolated from direct vision is that the brain is synthesizing imaging, into some interior layer. That way the person perceives 'sight'.
As a humorous aside, I recall some folks making a sarcastic comment, to medical researcher:
   "...They only THINK that they feel better"!
  But at any rate, in my case the tracking, between actual moving / waving hand looks perfect and immediate. The hand general POSITION in perceived visual field, is often offset by a lot. About 70 % of the times I do a brief check the actual hand is 4 inches to left or right, of the image. (Tested by opening eyes).
   That's why the term 'phantom limb' implies missing stimulus from retina, so the brain has to use motor movement hints, for creating the scene view.
(...whew...)
  With a 'suggestable' resting state (after exercise) I had been able to do some visualize work, attempting to visualize a 'green square', as a practice mentioned in ZEN and Yoga practice. Funny, my attempts always failed, initially, but often succeeded, only just after I gave up trying the focus!

   Later, I plan to describe simulation, using a 100 by 100 network of cells, that relates to musings on retina activity.
 

Online Nominal Animal

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Perhaps looking into mirror neurons and proprioceptors would be illuminating?
 

Offline greasemonkey

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A very interesting read is Phantoms in the Brain: Probing the Mysteries of the Human Mind by V.S. Ramachandran.

I read it some years ago so I do not remember if it mentions conditions similar to yours. But definitely well worth reading.
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Offline MrMobodies

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I am having artifacts with my vision with low light, when I stare at something for about 20 seconds like words, I'd see them there for a couple of seconds or any outline of a shape or circle in the form of a blue light.

I think the symptoms I am seeing is like from visual snow, Palinopsia, image persistance/after vision but I don't know which one it is. During the lock down I was supposed to see a neurologist after my eyes tested okay but that all got forgotten about.

This started in late 2017 when one night I had food poisoning, a cold and after taking sleeping pill tablets I suffered from some seizure.

https://n.neurology.org/content/54/4/855


I am a bit frightened that I have either got cancer or some kind of progressive disease if it is not caused by any prescriptions I take.

Just found this:
https://www.uspharmacist.com/article/optic-neuritis-a-brief-review


Quote
The function of the optic nerves is to transmit information from the retina to the brain for visual perception. Light striking the photoreceptor cells triggers a neurotransmitter response that generates action potential in the axons of the retinal ganglion cells for transmission to the brain via the optic nerves. The myelin sheath accelerates the conduction of the action potential through the axons of the optic nerves and tracts. Myelin is present in segments along the axons (FIGURE 2). This arrangement speeds up conduction of nerve impulses as the action potential jumps from segment to segment along the axons to visual centers in the brain.


« Last Edit: June 26, 2021, 07:04:34 pm by MrMobodies »
 

Offline greasemonkey

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I am having artifacts with my vision with low light, when I stare at something for about 20 seconds like words, I'd see them there for a couple of seconds or any outline of a shape or circle in the form of a blue light.

I think the symptoms I am seeing is like from visual snow, Palinopsia, image persistance/after vision but I don't know which one it is. During the lock down I was supposed to see a neurologist after my eyes tested okay but that all got forgotten about.

This started in late 2017 when one night I had food poisoning, a cold and after taking sleeping pill tablets I suffered from some seizure.

If I were you I would not rely on self-diagnosis. Reading medical papers can drive you mad. I would maybe resort to it if doctors could not find what is wrong?

BTW how did you come up with cancer or neuritis?

Also the best advice you may get here is "thou shall check voltages" or do a recap  :-//.
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Offline MrMobodies

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BTW how did you come up with cancer or neuritis?

Also the best advice you may get here is "thou shall check voltages" or do a recap  :-//.

My eye tested healthy before the lockdown when the artifacts started and the specialist told me that the next step is to see a neurologist for a brain scan but not it is getting worse. If I need a brain scan for that I always fear the worst and think of cancer or some kind of progressive disease and from the stuff I have been reading about it.

https://www.sciencedirect.com/topics/veterinary-science-and-veterinary-medicine/palinopsia#:~:text=Palinopsia%20is%20a%20reported%20cause,and%20the%20use%20of%20anticonvulsants.&text=In%20patients%20with%20stroke,%20palinopsia,symptoms%20may%20persist%20for%20years.
Quote
Palinopsia
Palinopsia is the visual perseveration of images over time, i.e., a recent image either persists after the object leaves the visual field or recurs after minutes, hours, or even days.131,132 In the latter case, the palinoptic images may be incorporated into the visual stimuli in the present environment, such as a cigar or beard appearing on the faces of all persons at a party. Palinopsia usually occurs in patients with impaired vision who are not entirely blind.133 Hallucinations and the illusion of visual movement are common.134

One autopsied patient with palinopsia had a subcortical infarct that undermined the right lingual and fusiform gyri.132 It seems that both left- and right-sided lesions may produce palinopsia.135 Palinopsia is a reported cause of brain tumors

Maybe I am worrying too much.
« Last Edit: June 27, 2021, 02:53:12 am by MrMobodies »
 

Offline greasemonkey

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Maybe I am worrying too much.

At risk of causing you a meta-worry (i.e. a worry about worrying ;D) stress may lead to bigger problems. The best book I have read on the subject is Sapolsky's Why Zebras Don't Get Ulcers.

Certainly a better read than medical papers ;).

Also bibliotherapy is a recognized form of therapy. None of that Freudian and behavioral crap  :-+.
« Last Edit: June 27, 2021, 03:17:49 pm by greasemonkey »
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Online Nominal Animal

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stress may lead to bigger problems.
I'm a near perfect example.  Psychologically tested to have extremely high tolerance for and capability of dealing with stress in my twenties, I now get psoriasis flare-ups from thinking about going to the grocery store with my inexpertly shaved head; and my ability to perform professionally is not defined by my skill set or technical ability but by my inability to handle interpersonal stress without crashing (the human equivalent of a computer locking up).  As a typical Finn, I trained myself over a decade or so to augment my diminishing stress tolerance with adrenaline: used bottled-up anger as the fuel to keep going.  Not a good combo, and while it resulted in somewhat entertaining stories, it is not something I wish anyone, even my worst enemy, makes themselves live through.  (And if you wonder: No, "using" adrenaline as "fuel" has nothing to do with being violent or dangerous; it is just another stress hormone affecting human behaviour, after all, and not some magic violence trigger.  I'm safe and harmless as a bunny, and have always been.)

Continuous stress is to be avoided and dealt with, because when it becomes the status quo, the detrimental health effects start piling up (exponentially?), and nobody can tell exactly what those effects are beforehand.  And usually not even when/after they happen, whether they are related or not.

Biologically, the purpose of stress hormones (in particular, cortisol, adrenaline, and norepinephrine, in humans) is to change our behaviour in a stressful situation, whatever that may be.  Ignoring them, and keeping oneself in the stressful situation is something the human body has not evolved to tolerate at all, so the end results of that vary wildly from prematurely graying hair to having your body essentially starting to shut down completely.  Undesirable things all.

It is well known to those familiar with livestock and wild animals, that many species in fact do quite easily die from sudden stress; and that some cannot sustain even moderate stress for longer durations, they just die from the stress.  Humans are more robust in this manner, but not qualitatively different.

(Reindeer have evolved this into somewhat a guard against predation.  When stressed/scared, urea-based chemicals start spreading in their musculature, making the meat inedible if the stress remains for any duration.  Essentially, if you scare and keep a reindeer running for a few minutes before slaughter, all of the meat will taste like piss so strongly it is inedible to anything with working taste buds.  The Finnish term for this is "juoksuporo".)

So, please, do consider prolonged stress a serious health hazard, to be avoided and dealt with like any physical ailment would; and nothing to be ashamed of when dealing with.
« Last Edit: June 27, 2021, 02:10:14 pm by Nominal Animal »
 
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