On an incredibly simplistic level, you can think of depression as occurring when your cortex thinks an abstract thought and manages to convince the rest of the brain that this is as real as a physical stressor.
Robert M. SapolskySome Poor grad student pressing on the flanks of a hamster and out comes a doctorate on the other side
Robert M. SapolskyGenes are important for understanding our behavior. Incredibly important - after all, they code for every protein pertinent to brain function, endocrinology, etc.
Robert M. Sapolsky...I might continue to believe that there is no god even if it were proved that there is. A religious friend of mine once remarked that the concept of god is useful, because you can berate god during the bad times. But it is clear to me that I don't need to believe there is a god in order to berate him.
Robert M. Sapolsky