To Ron Vetter: Yes, your thoughts are most interesting, don't quit. I too wondered about the difference between conscious human counting of seconds, pulse beats, or whatever, and the rats' mechanism which has to be subconscious. Dementia in PD is subtle but very real, and anything we can learn about it will be valuable. Cheers, Joe J. R. Bruman (818) 789-3694 3527 Cody Road Sherman Oaks CA 91403