How does the substantia nigra cause depression?

No. The substantia nigra is part of the movement system and not the emotion system. For example, destruction of Dopamine neurons in the substantia nigra is the cause of parkinson's disease.

Related Questions

What makes stimulating the substantia nigra cause depression?

Dopamine. Stimulation (presumptively by amphetamines) causes a release of dopamine. If this is "supraphysiological" - i.e., more than the body would normally account for - you can end up with a Dopamine deficit. This is the same think as Cocaine addicts have after a run on cocaine, or crank or meth addicts have after a run. The good news is that the body can and will build it back up if allowed to. Read more...