Deep brain stimulation is a method to alter brain functioning. The idea behind this technology is that scientists implant a small electrode deep within the brain. This electrode delivers controlled jolts of electricity to the surrounding brain tissue. Depending on how it is placed, it can either increase or decrease brain activity in specific areas.

Deep brain stimulation has been used to improve people's mood. The DBS device has been placed in several different locations to get an antidepressant effect. The area with the most evidence for an antidepressant effect is when the device is placed in an area of the brain called Broadman Area 25. This area is located nearer to the frontal part of the bain. In regular healthy patients increased activation of this area is associated with feelings of profound sadness. People with depression, on the other hand, have abnormally high activity in this area. So a DBS device can reduce activity in this area. In a preliminary study it lead to a striking improvement in patients with major depression. It can reduce the extreme sadness that is associated with the disease.

Researchers have also targeted an area of the brain called the nucleus accumbens. The nucleus accumbens is one of the main reward related regions of the brain. When a DBS device is planted in this area, it can improve anhedonia. Anhedonia is the inability to exprience pleasure, and it is a common trait found in many schizophrenic and depressed paitents. So the DBS device can increase the amount of pleasure a person experiences. A device in this area, though, has little effect on other depressive symptoms. Researchers have also found that a device in this area can potentially make a person euphoric. So they have to be carefull to adjust the device just right so as not to make the person too happy.

There are several other areas that DBS devices have been implanted in to improve mood. Another area is called the globus pallidus. The researchers were actually implanting the device their to improve a movement disorder, but they also found that the patient's depression improved substantially. The lateral habenula is another area that may have antidepressant properties. An overactive lateral haenular leads to less serotonin, norepinephrine and dopamine in the brain. So decreasing activity there may increase those neurotransmitters and thus improve mood.

Deep brain stimulation carries several risks because a person would have to undergo brain surgery. There is even a minor risk of death involved, so this treatment may always be limitied in scope. However, in the future it may increasingly find use for treatment resistant mental disorders.