War spoils. Soldiers who served in the 1991 Gulf War returned in large numbers with a multitude of health problems -- headache, joint pain, fatigue, and memory and concentration impairments. These problems have in many cases continued over the 12 years since. Roberta F. White, a MED professor of neurology, Susan Proctor, an SPH research associate professor of environmental health, and colleagues at the School of Medicine, the School of Public Health, and the Veterans Administration Boston Healthcare System are conducting an ongoing series of studies that began in 1991, soon after the war ended. The studies are aimed at unraveling the causes of the veterans’ ill health -- what is commonly known as Gulf War syndrome.
Using a battery of tests to assess physical, neuropsychological, and psychiatric health, the researchers compared veterans of the Gulf War with a group deployed in Germany during the same period. One of the instruments, the Medical Outcomes Study Short Form Survey (SF36), is a well validated tool that also allows the researchers to compare the veterans’ health status with established norms for the general population in the United States.
White and her colleagues found that the functional health status of Gulf War veterans was significantly lower than that of the group deployed in Germany as well as the general U.S. population. They found that as expected, the health status of the Germany-deployed group was higher than that of the general population. According to the researchers, this is because those who enlist, serve, and remain in military service are a self-selected group that tends to be more physically fit than average.
Although none of the studies established a “syndrome,” strong associations were found between environmental exposure -- to pesticides, debris from Scud missiles, chemical and biological agents, and smoke from tent heaters -- and symptoms relating to specific body systems. In related studies, the authors found that although veterans with post-traumatic stress disorder and major depressive disorder reported more health problems than those veterans who appear psychologically healthy, the latter also describe significant health problems arising after they returned from service. The most recent study, of functional health status, identified current medical and psychological conditions that lead to lower health-related quality of life for Gulf War veterans.
Hidden Persuaders, revisited. In the fall of 2001, Takeo Watanabe, a CAS associate professor of psychology, published a paper in the journal Nature presenting evidence that visual learning takes place in the absence of awareness, attention, or even relevance to the task at hand.
In follow-up experiments Watanabe and department of cognitive and neural systems graduate student Aaron Seitz (GRS’02) found that although subliminal, the learning that takes place in such situations is active. Their results show that an internal reward can be triggered when a subject successfully recognizes a relevant stimulus. This reward can help the subject learn irrelevant, and even subliminal, information presented at the same time.
Watanabe and Seitz asked subjects to identify specific letters out of a series of letters presented on a video screen. In the background was a field of randomly moving dots within which a small number of dots were moving coherently in one direction. Each of four different directions of motion were presented during the experiment. A “designated direction” was always paired with the targets of the letter-identification task, and the other directions were randomly associated with distractors from the letter task.
The researchers found that the ability to correctly identify the direction of motion improved only for the “designated direction” -- the one that was paired with the correct letter in the identification task. Learning did not improve for directions paired with distractors from the task. The researchers also designed tests that enabled them to rule out the possibility that distractors were inhibiting the learning of the direction of motion, rather than correct identification acting as a stimulator for learning.
Watanabe and Seitz speculate that the reinforcement signal is probably mediated by neurotransmitters such as acetylcholine, noradrenaline, and dopamine from subcortical brain areas, which are widely released during task-related processes. By deeper understanding of how perceptual learning is enhanced by association with performance of a different task, the researchers hope that new rehabilitative and educational strategies can be developed.
This research appeared in the March 6 issue of the journal Nature.
Briefs" is written by Joan Schwartz in the Office of the Provost. To read
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