Sensations Evoked In Patients With Amputation From Watching An Individual Whose Corresponding Intact Limb Is Being Touched

by mo on Tuesday, April 12, 2011

This article introduced me to the idea of "mirror neurons" – it took me a while to understand it actually. So here's the scenario:

If I was to watch someone pinch their right arm, I can see that they are making the physical act of pinching their arms – but because I know that my intact right arm is not being pinched, I feel empathy, not pain, when I watch them pinching themself. 

However, if I had an amputated right arm from which a phantom right arm developed, and watched someone pinch his or her right arm, I would feel the sharp pain on my phantom right arm even though no one had physically touched it (not that they can anyway). This is because my mind has no physical gauge to tell me that what I am have seen happening to the other person's right arm is not happening to my right arm:

"If one’s arm is amputated, one should suddenly start to experience the sensations of the same-side arm of other people when one watches them" (Ramachandran 2009, p. 1281).

So basically, these mirror neurons control our sense of empathy – but with a phantom limb, the lack of mirror neurons pertaining to that body part that once physically existed means that patients often have unexpected phantom sensations that they cannot control – I found this fascinating. I don't know what I'll do with this yet in terms of translating it into design, but nevertheless it provides for some very engaging research that relays to us the power of our vision in controlling our mind's perception of our physical bodies.   

Some notes from the case study testing this idea about "mirror neurons" whereby patients with phantom limbs had subjects stroking their own respective intact limbs while sitting in the patient's of vision.

"The stroking of the thumb of the assistant elicited sensations of being stroked on the phantom thumb, pinky to pinky and palm to palm. The third and forth digits were not delineated; on many trials there was a ‘diffuse’ sensation that spread across and beyond those digits in the phantom hand when either of those fingers of the assistant was touched" (Ramachandran 2009, p. 1282).

"The results clearly show that when a person who has had a limb amputated watches the corresponding intact limb of another person being touched, the former person experiences it in his or her phantom limb" (Ramachandran 2009, p.1283).

Reference: Ramachandran, V.S. & Brang, D. 2009, "Sensations Evoked in Patients With Amputation From Watching an Individual Whose Corresponding Intact Limb Is Being Touched", Archives of Neurology, vol. 66, no. 10, pp. 1281-1284.


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