>> Let's move on to the next part. When we are talking about initiating movement, maintaining movement or terminating movements. Two diseases, PD and HD come into our attention. So I want to talk about Huntington's Disease with a little bit more depth not very much deaf, but a little to tell you. Huntington's disease is a landmark disease in our history of medical research. Clinically, Huntington's disease is an autosomal dominant disease. It means we inherit one bad chromosome from either father or mother, the kid will have a disease. Therefore, overall transmission will be 50%, overall. Now, it's a progressive disease. In most case, Huntington's disease patients, they don't see any symptoms until they are 45, 50, 55 like that. So in the first phase, they look perfectly normal leading a normal life. There's no clear indication of whatsoever. Starting from somewhere, people first have subtle cognitive deficits and many of them also suffer from psychiatric disease. Later on, they have very small changes in the fine tuned movements. Later on yet than that, you have a major observable change in their movement. And that point, we call it, Chorea. This word is pronounced as Korea, just like Hanguo, Korea. Exactly the same pronunciation. It's a Latin word, it only means dance. As a matter of fact, if you watch movies or a play, there's a word choreographer. The one who designs how we with music and dance, and all that, choreographer. In Chinese, [FOREIGN] is that word. Chorea, choreographer. Now in that phase, patients develop major observable actions. They just cannot move. Their heads are jumping back and forth. Hands are waving and body trunks are doing like that. Huntington's disease is caused by one gene and it's the mutation in Huntington. Huntington in their first axon, there is a stretch of CAG, CAG, CAG, which is in all human being. In you and me. But normally, we have maybe 17, 18, 20 CAG repeats. If the CAG repeats, the number of that increases above 35 or above 40 to be safe, then this person is almost certain. 100% than this person will get Huntington's disease. The CAG expansion. Look at the brain. On the left-hand side, that's a normal person's brain, probably died of other diseases. Heart attack, cancer or car accident maybe. And on the right-hand side, that is a brain of Huntington's disease. What do you observe? >> Enlarging of the ventricle. >> Enlarging of the ventricle, very good. [FOREIGN]. So, brain matter is being reduced. How about white matter? If you take a close look is white matter increases or decreased Huntington's disease in patient brain. It still decrease. Look at the contrast maybe a little sharper. But if you look the real area, for example, in the control brain here is the outline of the huge area of white matter. If you move here, it's so small. Therefore, in both grey matter and white matter. There's an overall atrophy of brain tissue, which is best simplified or is demonstrated by the enlargement of the ventricle. Now, I want to draw your attention to a very distinct structure right here. You see this one? That's the [INAUDIBLE] nucleus. Look at this side, it disappeared. It pretty much disappeared. That's where the main pathology is.
