In a new study that could improve the therapeutic efficacy of deep-brain stimulation (DBS) for psychiatric disorders such as depression, a team of scientists shows that, when DBS is applied to a specific brain region, it improves patients' cognitive control over their behavior by increasing the power of a specific low-frequency brain rhythm in their prefrontal cortex.
The findings, published April 4 in Nature Communications, suggest that the increase in "theta" rhythms, readily detectable in EEG recordings, could provide neurosurgeons and psychiatrists with the reliable, objective and rapid feedback they've needed to properly fine-tune the placement and "dosage" of DBS electrical stimulation. In Parkinson's disease, where DBS has been most successful, that kind of feedback is available through a reduction in a patient's tremors. But for depression or obsessive-compulsive disorder, symptoms can be more subtle, subjective and slowly emergent.
"This is a major step forward for psychiatric brain stimulation," said Alik Widge, the lead and corresponding author on the paper. Widge began the work while a clinical fellow at the Picower Institute for Learning and Memory at MIT and a research fellow at Massachusetts General Hospital (MGH). He is now an Assistant Professor of Psychiatry at the University of Minnesota Medical School. "This study shows us a specific mechanism of how DBS improves patients' brain function, which should let us better identify who can benefit and how to optimize their individual treatment."
DBS increases control
Heading into the research, the team, also led by Earl Miller, Picower Professor of Neuroscience at MIT and Darin Dougherty, Associate Professor of Psychiatry at Harvard Medical School and Director of the Division of Neurotherapeutics at MGH, knew that DBS applied to the brain's ventral internal capsule and ventral striatum (VCVS) has shown mixed results in treating OCD and depression. A common feature of both conditions is a deficit of cognitive control, the function of controlling automatic or habitual behaviors through conscious will (for instance, overcoming recurring negative emotions that are a hallmark of depression). Cognitive control is performed in part by the prefrontal cortex, which is involved in circuits passing through the VCVS region. Moreover, theta rhythms are believed to be a means by which neurons in the prefrontal cortex could synchronize and drive the activity of neurons in other regions.
Journal information: Nature Communications
https://medicalxpress.com/news/2019-04-deep-cognitive-augmenting-brain-rhythms.html
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