Describe the etiology and symptoms of Huntington's and of Parkinson's disease. How do these diseases of the basal ganglia differ from one another?
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The motor symptoms of Parkinson's disease, such as motor tremors, rigidity, loss of balance and coordination, and difficulty in moving, are caused by deterioration of the substantia nigra, whose neurons release dopamine to the striatum. In a few of the cases, it is inherited; thus it is also genetic. It is believed that the genes that contribute to the development of the disease play a role in cellular functioning and protein synthesis. The cognitive and psychological symptoms are most likely caused by Lewy bodies, which are an accumulation of abnormal clumps of protein that form within the neurons. Environmental causes include brain injury, exposure to toxins such as industrial chemicals, carbon monoxide, herbicides, and pesticides.
Huntington's disease is similar in that it is also a degenerative disorder of the motor system involving cells in the striatum and cortex. The symptoms progress from mild, infrequent jerky movements to involuntary movements that start as fidgeting, then as movements of the limbs, and finally as writhing of the body and facial grimacing. Unlike Parkinson's disease, cognitive and emotional deficits are well known in Huntington's. Such symptoms can include impaired judgement, difficulty in cognitive tasks, depression, and changes in personality. Motor symptoms are caused by degeneration of inhibitory GABA-releasing neurons in the striatum. Psychological symptoms are caused by degeneration of or defects in neurons in the cortex. There is also a better understanding of the genetic vulnerability of developing Huntington's disease, with a stronger hereditary rate (50%) than that of Parkinson's (less than 10%).
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A) Billy's father was also very aggressive. B) Billy's doctor found that Billy has exceptionally high levels of testosterone. C) Billy's friends are also very aggressive boys. D) Billy's mother consumed a great deal of alcohol when she was pregnant with Billy. E) Billy watches a lot of violent cartoons.
Seventy-year-old Ace decides that he cannot remain effective at all types of gambling so he decides to focus only on blackjack, with the hopes that this narrow focus will allow him to perform better in this one area. According to the SOC approach, the decision to abandon other forms of gambling represents
a. selection. b. optimization. c. compensation. d. plasticity.