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I've looked it up in plenty of places like the Wikipedia page and such, and it is clear that the most common cause of Paresthesia is either a fair amount of pressure on a specific patch of skin causing lack of blood flow to the specific nerve endings in that limb (not to be confused with a stop in blood flow to the limb altogether) or a much stronger amount of pressure on that patch of skin for a shorter amount of time. This, although the most common cause, is not nearly the only one, which could be anywhere from simply sleeping on the wrong side of the bed to a lethal injection. I'm wondering what happens to the nerve cells that are affected at a cellular level, and what causes it at a cellular level. The level at which pounds per square inch aren't what is being noticed.

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Underneath the superficial layers of your skin there are receptors which sense pressure, temperature and pain. These receptors are part of the peripheral nervous system which senses stimuli and they take the message conveying details about the stimulus to the somatosensory cortex of the brain. Here is where the perception of pain, burning, pressure etc is ultimately made. To take the simplest example, if you stop blood flow for a short amount of time in a limb, these receptors are activated, and will send signals to the brain that are interpreted as tingling or numbness. With more severe pain, different receptors are activated which , again, project to the same brain area but a different message is read out. If the pressure from one limb is removed, the receptors will go back to normal function as blood flow is restored.

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The main reason I asked this question was to hopefully get an understanding as to whether it would be possible to stimulate a group of these cells in the peripheral nervous system to induce the feelings of tingling numbness from outside of the skin using a form of directed energy such as directed sound or a laser. The problem with finding the right kind of stimulus is that I don't know whether the cells send out an electrical signal back to the brain or some sort of chemical signal. Do you know if it's possible, and if so with what kind of stimulus? –  Ethan722 Mar 26 at 3:54
    
This would in theory be possible. You would have to create a stimulus which matches the response profile of the receptor you want to target. The signals to the brain are electrical-- between cells-- but locally release of chemicals can triggers the electrical signals. For example during injury, the body can release certain chemicals which can numb pain at the release site and your brain perceives this as "reduced pain". A lot of sensations can be felt outside the skin already. If you think about sensing a hot oven just by going close to it or air pressure from a blow-dryer on your skin. –  V_ix Mar 26 at 17:26
    
So without considering something which would cause excessive nerve damage or that would last longer than a common case of paresthesia, what kind of stimuli could stimulate the nerve clusters through the skin in the same way as stopping blood flow. While I was reading about the sensation, I saw somewhere that it could be triggered with an excessive amount of vibration like in the case of motorcycle riders while they grip their bikes over jumps, which is known as, "cyclist's hands". This is why I'm thinking a directed sound device could create the vibrations with a high enough frequency. –  Ethan722 Mar 26 at 18:53
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