Reading in a book called Introduction To Neuropsychology by J. Graham Beaumont, I found this symptom of a certain kind of parietal lobe damage that I'd never heard of before: "Apraxia Certain apraxias (the loss of intentional movements) may arise from parietal lesions. These may occur in the absence of paralysis or of any impairment of sensory or motor function. They may relate to almost any kind of purposeful movement, although gross proximal movement of the body and limbs are more commonly affected. However, intentional movements of the face , tapping and complex manual sequences do not escape impairment. The patient is unable to organize some motor task if he must start from the most abstract description of that task. In other words, he may be perfectly able to carry out some movement automatically, or in the context of everyday life, such as drinking from a cup, or striking a match, but asked to demonstrate how to drink from a cup or strike a match, the patient is quite unable to do so. Sometimes he may find it possible if he has the relevant object to act as a cue, but he will fail if asked to perform the action without a cup or a match to act as a trigger. " p. 102
Hi, Apraxia are very common with Right stroke patients (left brain injured). We are seeing every day these weird behaviours. http://www.ninds.nih.gov/disorders/apraxia/apraxia.htm
Thanks for the link. It's kind of amazing that the problem is not that they can't do certain things, but that they can't do them on command. They aren't able to get from the concept of the action to the action, despite the fact they can perform the action when it comes up naturally. A very complex problem.