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Tom, Let me start by saying, that I am not actually opposed to what you are saying about vision and movement. But I do have some reservations. I think Ida put her finger on my concerns when she wrote: "For example, when someone says dyskinesia diminishes by closing your eyes, I immediately think, because I studied psychology: that can be true but if it is true, what does it mean? I know that by closing your eyes the whole nervous system comes in a different state of arousal and activation (which are two different things) and that may influence dykinesia. So you can't conclude from the fact of influence allone that it is the influencce of a part of the visual system that does it. My conclusion is that, if we want to proceed with this project, we need a basic understanding of neurophysiology" For example in the long list of activities you mentioned as dyskinesia suppressants all bar looking through a zoom lens require movement. So in each case two things are happening - optical flow is being accelerated and the subject is involved in physical activity. Whilst it is possible that any decrease in dyskinesia is the result of changes in the rate of optical flow it is also possible that it results from the activity. Lending support to this possibility is your statement that the activity with the greatest rate of optical flow, but least physical activity, riding in a car, has no effect on dyskinesia. I assume, as you are about to publish a paper on the subject that you have addressed and resolved this question. Would it be possible to give us an idea as to how you eliminated that possibility. As regards akinesia I have found that when very bradykinetic and functioning just above being frozen that my finger will freeze holding down the mouse button on the 1st click. Some time ago I discovered that if I close my eyes I can usually unfreeze my finger and then if I keep my eyes closed I can sometimes even manage a double click that works, albeit at the slow speed I have my system set to. I have also found that I can achieve exactly the same results if I keep my eyes open and look anywhere but at my monitor screen and keyboard. Something definitely happens, but what - and where? Tom - I hope your paper excites enough interest to attract some money and resources to a study of your theories. Whatever the outcome of such a study, the facts established will contribute to the understanding of PD and consequently will hasten the cure. Thank you Dennis. ----- Original Message ----- From: Tom Riess <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, 13 August 1999 12:29 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 >