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First off, I don't know if this is a normal healthy thing to occur. There have been many times where I have an itch on say my arm and I scratch it, only to feel the scratching elsewhere on my body. I assume somewhere along the transit of the touch signals to my brain the signal gets mixed up and is processed incorrectly.

So my questions are:

  • Why does this mixup happen? (chemical imbalance, damaged nerves, etc..)
  • How does my brain correspond the touch to somewhere else? (what is the process behind it)
blep
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kittycat
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    You might be interested in this. And this. – terdon Apr 01 '13 at 17:28
  • @terdon: Thanks for the links, but interesting as they are they don't answer why the touch signals get crossed =o(. Irregardless if it is an itch or another form of touch, the brain should not be interpreting a touch on one part of the body as coming from another part. My question is why this mixup occurs and how the brain is incorrectly processing it. – kittycat Apr 02 '13 at 11:20
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    I know, that's why I posted a comment and not an answer. Just thought you might be interested. – terdon Apr 02 '13 at 11:48
  • Could you clarify exactly how the sensation is wrong for you? You are supposed to have an itch for whatever reason, and when you scratch it it's supposed to go away and you get the touch sensation of your fingers instead. All in the same place of course. Are you saying that the actual touch sensation of your fingers on your skin is mislocated? If so, is there a regularity to where it is mislocated (e.g. symmetrical to body axis)? And does this only occur on skin that was itching before, or any part at any time? – Armatus Apr 03 '13 at 17:58
  • @Armatus well the last time it happened I got an itch on the back of my arm and scratched it only to feel the scratching on my lower back. I don't recall which body axis they were at, I'll have to note that next time it happens, but it's rare. No, it does not occur on skin that was itching before. – kittycat Apr 03 '13 at 18:06
  • What I meant was things like, if it was mislocated on the same spot but opposite side of the body for example; but it seems to be random. The other question was what exactly causes it to happen - does it only occur when you are scratching yourself after you were itching or also in other situations? – Armatus Apr 03 '13 at 18:43
  • @Armatus I've only observed it happening when there is a random itch, but no prior itching, but not all itches have it happen. That's why it is so rare, I've only experienced it around two dozen times in the past ~15yrs. I'm 23, I'm assuming it may have happened when I was younger, but I never thought much of it since was just a kid. – kittycat Apr 03 '13 at 18:48
  • How clear is that sensation? Does it correspond to your finger movement, i.e. are you certain that it is a misprojection of the sensation (onto the wrong part of your body)? With such a rare occurrence it could just be a random error. – Armatus Apr 03 '13 at 19:01
  • @Armatus yes, it does correspond. If I stop scratching the itch, the touch sensation on other area of body stops, and if I start again it starts. I can't reproduce it later on, maybe because I can't find the exact spot the itch was, which is where the error is being triggered. If it is a random error, how and why would such a thing occur? – kittycat Apr 03 '13 at 19:09
  • My mother explained this to me when I asked because I also get the same thing. I believe it is hereditary because she also gets this. She called it twisted nerves but it is not common at all. Scratch your side, feel it on your leg, go to your leg you feel it on your arm, scratch your arm and then you feel it on your back. No, it doesn't happen all the time and is a weird feeling when it does. It doesn't have a magic button where it always happens in the same place for the same reason because it isn't caused from an injury. My mother participated in a medical questionnaire when she was in her t –  Sep 24 '13 at 15:13
  • I get a similar weird nerve sensation happen to me. I can run my fingers down or up the outside of my leg and i feel the sensation on the inner side of my leg? Its weird and i have had it happen in different places on my legs. I would like to know WHY this confusion of sensation happens? I do suffer from multiple level high grade thoracic (T5 to T10) cord compression from herniations onto a tethered thoracic spinal cord (stuck to the bone) peripheral neruopaphy and autonomic nervous system dysfunction, (ideopathic Hypersomnia, Gastroparesis, swallowing difficulty, heart palpatations and low BP – Robyn Schindelbacher Oct 17 '18 at 00:53

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Well nerve crossing or misinterpretation of nerve signal by the brain does not happen all the time. In case it happens frequently then I guess it would be Multiple Sclerosis or might be Fibromyalgia syndrome. In multiple sclerosis, the Myelin sheath surrounding neuron when gets damaged causes certain problem with nerve signal transmission to the brain. But that is not the main cause. The main cause can be found in Neuropathy:

When nerve cells are damaged, perhaps by a temporary restriction in their access to oxygen, they too atrophy or shrink a little, thus the synaptic junctions widens. Just like with a spark plug in your car or lawn mower, if this gap gets too wide, the spark cannot make the jump. A normal sized nerve signal cannot jump this enlarged gap either, so the signal either does not get through or it gets misdirected to another part of the body and is misinterpreted as pain.

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So I can say that the nerve cells in the place where you feel real pain fails to transmit the signal to brain via its neighboring nerve cell instead that signal passes through some other node randomly (or it might take the same path every time you touch the pain area) and signal the brain which gets misinterpreted and make you feel that you have pain in the misinterpreted region.

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Pradeep S
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This is part of a neuro issue...like seeing numbers in color, or touching something but feeling it in another part of your body. The sensations are processed in the brains communication area and ifeas/sensations get mixed or crossed. 4% of the population has these experiences. You aren't odd; you're exceptional.

Kris
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  • Welcome to SE Biology. Because this is a straight Q & A site rather than a chat site, our expectations of answers are perhaps different from other sites. You can read the help on writing good answers here. In particular, we expect you to provide evidence of some sort in support of opinions or information you provide. This is best done by a reference to a scientific paper or a reputable source on the internet, such as Wikipedia or one of the text books on NCBI bookshelf. I suggest you might consider editing your answer with this in mind. – David Dec 30 '18 at 16:42