[From Rupert Young (971018.1230 BST)]
The other night I saw a fascinating program that demonstrated so evocatively
how important feedback is in even the simplest everyday movement. In 1971, as
a young man, Ian Waterman woke up totally unable control his body. However,
he had not lost the ability to move his muscles and limbs but had lost all
touch and feeling in his body, below the neck. In essence he had lost all
sensory feedback of the position of his limbs (he could still feel pain and
temperature). He had been struck down with a very rare disease that has been
called Sensory Neuronopathy (not sure of the spelling).
Against all odds, and the prognosis of doctors, he has made a miraculous
recovery and his body movements seem almost normal. He has achieved this with
two main techniques. Firstly, visualisation and imagination. Even now he has
to think about, visualise and plan every movement that he is going to make
every minute of the day, nothing is done automatically. And second, visual
feedback. As long as he can see his limbs he is able to control them. Early
in his recovery if his hands went out of sight they were completely
uncontrollable and just careered all over the place. He recovered enough to
be able to cook, but if the electricity meter ran out and the lights went he
would just collapse, with pans flying everywhere, suffering total sensory
deprivation. When he walks he must continually look at his feet, otherwise he
will fall over. Surprisingly, he has very natural hand gestures which the
neurologists think may be automatic but which still break down severely
(though not completely) without visual feedback.
In everyday life we are unaware that we are contuinually getting feedback
about the positions of our limbs and how essential that feedback is. Ian is
able to produce the output for the muscles but is still unable to control his
limbs. So this condition seems to demonstrate very clearly that merely
controlling output doesn't work, but that the only use of output is to control
input. Or am I looking at this with PCT-tinted spectacles?
Regards,
Rupert