A team of scientists from Princeton University has devised a new experimental technique that produces some of the best functional images ever taken of the human brainstem, the most primitive area of the brain.
The scientists believe they may be opening the door to inquiries into a region that acts as the staging area for the brain chemicals whose overabundance or absence in other parts of the brain are at the root of many neuropsychiatric disorders, like addiction, schizophrenia and Parkinson's disease.
Reporting in the Feb. 28 edition of Science, the scientists describe using functional magnetic resonance imaging to study brainstem activity in dehydrated humans. The scanning technique allows researchers to watch the brain in action.
The subjects were participating in classical conditioning experiments in which they were presented with a visual clue, then, at varying intervals, given a drink. The researchers were able to track changes in blood flow in areas of the brainstem associated with enhanced activity of the brain chemical dopamine -- as the person experienced either pleasure or disappointment at receiving or not receiving the reward.
"For a long time, scientists have tried looking at this area of the brain and have been unsuccessful -- it's just too small," said Kimberlee D'Ardenne, the lead author on the paper. Until now, scientists wanting to use brain scans to study brain chemicals like dopamine were relegated to watching its effects in other more accessible parts of the brain, like the prefrontal cortex and ventral striatum. However, this was downstream of its source, and therefore possibly much less accurate, D'Ardenne said.
"We wanted to try because the brainstem is so important to activities in the rest of the brain," said D'Ardenne, a postdoctoral student in the Department of Chemistry. "We believe it could be a key to understanding all kinds of important behavior."
For the research, D'A
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