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As one of those who started the ball rolling along the Avoiding Sinemet trail, I think I had better re-state my concept of how a Pallidotomy works, and what is going on. First, consider a normal person. Their nervous system is a splendid example of a closed loop control system. In the real person the signal and feedback loops are an amazing 3-dimensional network, I looked at a paper on the subject for about 20 seconds, and decided to go back to ny simple system - but we can still play with the concept. Now consider the PWP, having lost nearly all his Dopamine production, and only an intermittent, weak and feeble signal getting through. I believe that in priciple it doesn't matter which line is degraded- it could be the supply signal, or the feedback signal; it just depends on your frame of reference. Finally, the Pallidotomy does Not sever anything: I believe the term used is a'lesion', which I take to mean partial severence of a bundle of nerve fibres in the Pallidus: these form a part of the feedback loop, and I repeat that they are only partially cut. (I am not inventing this- I really believe that that is what is done in the real operation. Maybe someone can check on that?. This is why the patient is conscious- so that the surgeon can tell by the absence of symptoms, when to stop cutting. The resulting weak output signal is again at the same approximate level as the supply. The reason why thePWP has to continue taking Sinemet may be to provide a strongeer signal as well. Thanks to all who contributed to this (speculative) discussion. Regards, -- Brian Collins <[log in to unmask]>