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Hello Tom, et al..... Is there any data on PWPs who have lost their vision? Or, who were blind from birth? I have always wondered about this.... Margaret Help us save the horses! Habitat for Horses, Inc. A lifetime home for abused, endangered horses. http://www.habitatforhorses.org/ -----Original Message----- From: Parkinson's Information Exchange [mailto:[log in to unmask]]On Behalf Of Tom Riess Sent: Friday, August 13, 1999 12:29 AM To: [log in to unmask] Subject: towards and understanding of akinesia - dyskinesia Normally optical flow is perceived and processed through peripheral vision which sees motion exclusively. Such peripheral processing of motion is impaired in PD but it is possible to perceive and process optical flow in the central field of vision under the proper conditions. When this is done one can overcome both akinesia and dyskinesia. I have suggested that akinesia and dyskinesia are different manifestations of the same underlying pathology and that a major component of that pathology occurs in the visual system. More specifically, this pathology involves the perception and processing of optical flow. Augmenting the perceptability or the velocity of optical flow overcomes both akinesia and dyskinesia. The following are examples of activities which accelerate or augment optical flow and these are activities that will suppress dyskinesia. Skiing, roller skating, riding a motor cycle or bicycle (but not in a car), walking on a moving sidewalk, walking on stilts, looking through a telephoto lens which is zooming in, walking towards a wall that is illuminated by a strobe light, running, regularly spaced cues on the floor, walking behind a rolling ball at the same speed as the ball and watching it roll, elevated (platforms) on the shoes and countless others. Those activities which can be performed while ambulating will overcome akinesia as well. In addition it is possible to induce dyskinetic gait in a normal (non- PD) person by purely visual means. This can be done by displaying real motion on the periphery which is interpreted as being virtual and having that motion mimic the apparent motion one would see if one were dyskinetic. All of the above lend credence to the theory of a visual component to akinesia and dyskinesia. Regards, Tom Riess