Brain stimulation alters depressive symptoms in mice
Findings may point the way toward treatment in people
Signs of depression can be turned on and off in mice with the flip of a switch. Activating or silencing the behavior of certain brain cells with laser light causes the animals to change their depressive behavior, two new studies find.
Although the experiments were done in rodents, the results have direct relevance to human depression, says neurologist Helen Mayberg of the Emory University School of Medicine in Atlanta. The new work may point out places in the human brain that doctors can similarly stimulate to treat depression.
The results, published online December 12 in Nature, took advantage of a technique called optogenetics, which allows scientists to control nerve cell behavior with a tiny fiber-optic light. In the studies, mice were genetically engineered to harbor nerve cell proteins that respond to light. The researchers could make certain nerve cells fire off messages by shining blue light, and quiet them by shining yellow light.
These cells, which produce the chemical messenger dopamine, nestle in a brain region called the ventral tegmental area, a spot known for handling rewards. This system may be skewed in people with depression, since the disorder often keeps people from responding normally to things that used to be enjoyable.