Cloudy memories, sunny predictions.Many scientists hold that the brain houses a number of specialized memory systems. Now, evidence for the existence of two such systems emerges from a study that also illuminates the impact of Parkinson's disease Parkinson's disease or Parkinsonism, degenerative brain disorder first described by the English surgeon James Parkinson in 1817. When there is no known cause, the disease usually appears after age 40 and is referred to as Parkinson's disease. on mental life. Parkinson's disease, which results in tremors and other movement disorders Movement Disorders Definition Movement disorders are a group of diseases and syndromes affecting the ability to produce and control movement. Description , causes people to lose brain cells that supply the chemical messenger dopamine dopamine (dōp`əmēn), one of the intermediate substances in the biosynthesis of epinephrine and norepinephrine. See catecholamine. dopamine One of the catecholamines, widely distributed in the central nervous system. to a strip of tissue called the neostriatum. Individuals with this condition find it difficult to track recurring events that, largely outside conscious awareness, shape their judgments, say psychologist Barbara J. Knowlton of the University of California, Los Angeles UCLA comprises the College of Letters and Science (the primary undergraduate college), seven professional schools, and five professional Health Science schools. Since 2001, UCLA has enrolled over 33,000 total students, and that number is steadily rising. and her colleagues. The neostriatum may belong to a brain system devoted to the gradual learning of both mental and physical habits, the researchers propose. In contrast, people who suffer another type of brain damage-which centers on a structure called the hippocampus-forget personal experiences shortly after they occur but excel at the so-called habit learning harmed by Parkinson's disease, Knowlton's group contends. The researchers examined 20 people with Parkinson's disease who showed no signs of mental deterioration, 12 individuals with damage to the hippocampus hippocampus fabulous marine creature; half fish, half horse. [Rom. Myth. and Art: Hall, 154] See : Monsters and related areas, and 15 volunteers with intact brains. The habit-learning task hinged on the ability to discern linked events in one's surroundings (SN: 7/13/96, p. 24). Cards bearing squares, triangles, circles, or diamonds were presented in combinations of up to three cards on a computer screen. Next, either a sunny or cloudy scene appeared. Certain card arrays appeared mainly before rain, others mainly before sunshine. Participants assumed the role of a weather forecaster attempting to predict from the cards the approach of rain or clear skies before the weather pattern appeared on the screen. By the end of 50 trials, volunteers with hippocampal hip·po·cam·pus n. pl. hip·po·cam·pi A ridge in the floor of each lateral ventricle of the brain that consists mainly of gray matter and has a central role in memory processes. damage and those with no brain damage had learned to predict weather conditions correctly in about 7 of 10 choices, the scientists report in the Sept. 6 Science. Those with Parkinson's disease made accurate forecasts only half the time, a rate no better than that achieved by guessing. Despite their predictive successes, hippocampal-damaged participants rapidly forgot what they had done and seen in the study. Parkinson's disease patients Famous people, past and present, with Parkinson's include: Living
|
|
||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion