Aunt Bean, I have also thought of donating my body or brain to PD research. Although, I not there 100% yet, but leaning in that direction.
I assume a major university doing PD research might be able to guide you through the process of donation. My brother-in-law in Louisville, KY has already made arrangements for his body to be donated to the University of Louisville (although not PD specific) as his mother did a few years ago.
Perhaps the MJF Foundation or one of the national PD organizations could help you in your endeavor. I know this is not for everyone but it is an important part of research. Bless you.
Here is a start from the Parkinson's Disease Foundation and MA APDA websites.
http://www.pdf.org/en/parkinson_brain_donation
http://www.apdama.org/site2.0/articl...n-Donation-131