A research team led by investigators at the Virginia Tech Carilion Research Institute has demonstrated the first rapid measurements of dopamine release in a human brain and provided preliminary evidence that the neurotransmitter can be tracked in its movement between brain cells while a subject expresses decision-making behavior.
"In an experiment where we measured dopamine release while a subject made investment decisions in a stock market trading game, we showed that dopamine tracks changes in the value of the market," said Read Montague, director of the Human Neuroimaging Laboratory at the Virginia Tech Carilion Research Institute and professor of physics in the College of Science at Virginia Tech.
"A startling discovery was that the dopamine signal appeared to be a very good indicator of the market value and in many instances a good predictor of future market changes," said Kenneth Kishida, a postdoctoral associate with the Human Neuroimaging Laboratory and the lead author on the report. Interestingly, the choice expressed by the subject did not always correspond with the prescient brain chemistry, he said.
The research was published on Aug. 4, 2011, in the Public Library of Science journal, PLoS ONE, in the article "Sub-Second Dopamine Detection in Human Striatum," by Kishida; Stefan G. Sandberg, senior fellow with the Departments of Psychiatry and Behavioral Sciences and Pharmacology, University of Washington, Seattle; Terry Lohrenz, assistant professor in the Department of Neuroscience, Baylor College of Medicine; Dr. Youssef G. Comair, professor and chief, Division of Neurosurgery, American University of Beirut, Lebanon; Ignacio Saez, assistant professor at Virginia Tech Carilion Research Institute; Paul E. M. Phillips, associate professor, Departments of Psychiatry and Behavioral Sciences and Pharmacology, University of Washington, Seattle; and Montague, senior author.
The researchers adapted their sensors to existing technology used for functional mapping of the brain during surgical implantation of deep-brain stimulation devices. "Deep-brain stimulation is typically used in the treatment of Parkinson's disease," said Montague. "Uses for treating other neurological disorders are also being investigated, though, and may open new avenues for the technology we developed."
The researchers applied criteria that employed experimental methodology that is "safe to the patient, compatible with existing neurosurgical apparatus and the operating-room environment, and capable of sub-second detection of physiological dopamine," they state in the article. They modified existing sensor technology to improve signal conductivity, creating a microsensor that shares the electrochemical properties of existing electrodes yet can detect sub-second dopamine release. "Even more important, the new microsensors are biocompatible and can be sterilized without affecting performance, " Kishida added.