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Tom, Thanks for your fast answers to my questions. Updates on the progress of your research will be appreciated. I think your idea of providing external aids to improve the locomotion of PWPs could be fruitful. For example,methods of providing aiding data for improving motion stability. You could also include other external cues such as acoustic and tactile activated by motion sensors. Regards. Gil ---------------- At 04:22 PM 4/23/98 -0400, you wrote: > > >Dear Gil, >Thanks for the reference - sounds very relevant. >Here's my attempt to answer your interesting questions: > >Some quesions on your paper: >1.Is gait a completely learned activity? >2.Isn't gait a genetically acquired capability? >3.Aren't there many motion control parameters other than visual flow? >4.How do blindfolded PWPs move? >5.Does your theory explain cogwheeling rigidity? > >------------------------------ >1 & 2: Would humans learn to walk in an environment where walking was >irrelevant? Perhaps, but whether or not gait is COMPLETELY learned is not >central to the point I was trying to make that there is an essential >interplay between the environment and the subject which determines the >characteristics of the resultant learned activity, the nature of the >learned information (ie. overlearned versus externally cued), and the >essential(but not exclusive) role that vision plays in this process. > >3. There are certainly other "motion control parameters" (for example, >proprioception) but on an empirical, non-neurophysiologic level none are as >imortant as those which are vision mediated. > >4. Closing one's eyes is an effective means of overcomming a freezing >episode, provided the immediate terrain is friendly and that freezing is >not a consequence of what I have termed "T-factor". This works presumably >by eliminating perception of inhibitory visual data (an aberrant or >non-responsive visual flow) but does not replace this data with enabling >data. > >5. I believe cogwheel rigidity is a manifestation of T-factor tone >introduced into the upper extremity by simulating the weightbearing state >of the lower extremity. While standing the lower extremeties have posture >maintaining tone. But in PD this tone is pathologically increased to the >point of rigidity. In the lower extremity the posture maintaining force is >constant whereas in the cogwheel test the force is gradually increased >until rigidity is overcome, following which the external force is increased >again inducing rigidity. Note that when a subject exhibits T-factor >akinesia on standing the same subject when in a crawling position will be >unable to "take a step" with his arms without first displacing his weight >to his knees. > > > > >