Proprioception and Phantom Limbs: : The pliability of body image at the neuronal level

Posted by Brittany Dingler

Proprioception is our central nervous system's awareness of the position and orientation of the different parts of our body in space, and in relation to one other. This vital ability is crucial, not only for allowing broad, gross movements, and small, incredibly fine-tuned coordination, but also for communication with our brains to provide constant distinctions between what is "self" and "non-self." This ability to distinguish our body from others may seem unimportant but a phenomenon known as Phantom Limb Syndrome shows the necessity and extent of proprioception.

The aptly named Phantom Limb syndrome describes the sensory perceptions one feels for a limb or digit that no longer exists. Essentially, because of our bodies' fine-tuned proprioceptive abilities, an amalgamation of precise signals provide feedback that we receive as touch and, from there, categorize further into sensations of pain, arousal, or a general tingling. Perhaps an abstract concept in the main, as the majority of the population has no personal context for such an intangible notion, the phantom limb phenomenon speaks volumes of how touch actually works and how, as hard as it is to believe, it truly is all in our heads. 

This ability for phantom limb to be experienced by anyone illustrates the pliability of body image. We are a compilation of what we think we are, a malleable sum which can change at any given moment. To wit, our body image, our multi-faceted perception of ourselves, does not, it turns out, have to do with the physical 'flesh and skin' body at all. 

This Gestaltist idea may have significant implications as we continue to learn how to best take advantage of our nervous system's capacity and propensity for artificial incorporation. Specifically, the ability to override and manipulate the interaction between our somatosensory cortex (essentially the "body-sensing" center in our brain) and our proprioceptors (the neurons responsible for sensing all changes in body position) may provide more opportunity to return to more normal levels of sensation in areas often affected by missing limbs, like intimacy. Such discoveries would be extensions from the understanding of what happens for some foot amputees during sex as a result of the proximity of the brain regions responsible for foot and genital sensations (Kalat, 2012). Ramachandran and Blakeslee (1998) believe this to be a result of neuroplasticity, such that the 'genital regions' moved over into the 'foot region' after detecting the available neuronal real estate. On a more practical level, this neuroplasticity behind the coupling of phantom limb sensations is crux to phantom limb therapy, rapid advancements in the function of prosthetic limbs and specifically, our ability to adopt a new body part as our own.