In this post, I will be discussing the case history of Ian Waterman, who suffers from an acute sensory neuropathy in which the necessary myelinated nerve fibers for proprioception have been damaged. That is to say, Ian does not have access to the information concerning the whereabouts of his various limbs. This proprioceptive sense is the sense that allows one to touch your fingers together with your eyes closed and in addition to maintaining a steady posture.
After the initial onset of this debilitating condition, Ian was not able to control his posture or initiate any motor commands. It was only after an intensely difficult learning process that Ian was able to regain motor control of his limbs through visual perception. That is to say, Ian must keep any limb that he wants to move, such as a leg for walking or an arm for grabbing, within his visual field in order to voluntarily control it.Thus, Ian is not able to maintain any semblance of upright posture or motor control in the darkness or when his attention is momentarily distracted from the concentrative thought of controlling his actions.
For simple actions that we have normally have overlearned motor schemas for, such as walking, Ian must devote a large amount of his cognitive capacity. He must consciously think about every step he takes. For every minute aspect of movement, Ian must devote full mental concentration. Using terminology from Gallagher, Ian must utilize his body image in a completely different way because his normal, learned body schema for motor control was destroyed by the neuropathological disintegration of his tactile/proprioceptive feedback systems.
Ian Waterman’s case is interesting in itself, but also sheds insight on the blurred distinction between perception, motor control, and our proprioceptive sensory systems. It is only through a unitary blending of these different modalities that we are able to seamlessly interact with our environment.
For more information, see:
Gallagher, S. (2005). How the Body Shapes the Mind: Oxford University Press.