The Bi-directionality of Dopamine Neurons

Depressive disorder includes a variety of symptoms such as anhedonia, hopelessness, and loss of motivation. The direct cause of depression is not known, yet it is postulated that since dopamine has an effect on the reward system of the brain. Therefore many treatments aim to emphasize the level of dopamine in system. Since it is difficult to target dopamine neurons directly, the methods found in the Tye et al article used casual contributions that induced dopaminergic effects to study how inhibiting or exciting the dopamine neurons effected the subject.

            I found it interesting that inducing or suppressing dopamine activity can either show signs of depressive behavior or have the opposite effect. At what level of dopamine activity is it necessary for an individual to be considered normal or suffering from depression? According to this week’s articles by Tye et al and Chaudhury et al as well as last week’s articles, antidepressants take weeks to have an effect. However last week’s articles highlighted effects of serotonin in depression as well. Serotonin is another key neurotransmitter that plays a role in the overall mood and emotional state. It was noted in further research that not all antidepressants work for an individual since their depressive state can be due to either low dopamine levels or low serotonin levels, or both.

            With all the research on antidepressants and their effects on treating depression, it would be interesting to see whether stimulating either dopamine or serotonin would have more of an effect in treating depression. Further research on dopamine neurons can show which downward path leads to the expression of depressive behaviors. By targeting the specific dopamine neurons, it can also be possible to see if similarly to serotonin based antidepressants if dopamine has any neurogenesis or neuroplasticity effect on the brain. With the knowledge that a dual directionality exist in dopaminergic pathways, it would be interesting to see at what levels dopamine inhibits or causes depressive behaviors.