What are the areas of professional practice that capture my interest (this might be a disorder, anything relating to treatment or diagnosis, etc.)? With respect to this general topic, what would an essential question for me be? What do I already know about this topic? What don't I know about this topic?

I am not really sure which areas of professional practice interest me the most. I have not studied or learned a lot about these topics yet. However, because I have a grandfather who suffers from Parkinson’s disease and have seen his experiences throughout the disease, I would like to learn more about the illness. What causes Parkinson’s disease and how does it affect one’s body (what happens physically)? These are things that I would like to find out. I know that it somehow affects the person’s muscles. It also changes the quality of one’s voice by making it breathy.
I do not know what happens to the brain. Before my grandfather’s illness progressed, he was able to talk, though it took him a while to say something and sometimes he would loose train of thought in the middle of his sentence. I am also curious as to why people shake. The person suffering from Parkinson’s disease has a rapid shake-like movement in his hand. What causes the muscles to do this?