Figure 1
From: Genomic studies of mood disorders - the brain as a muscle?
A putative model of the relationship between environmental stimulation, growth factors, and the function of the brain regions involved in mood regulation. The degree of environmental stimulation influences growth-factor levels and brain volume in the brain regions that are involved in mood regulation. In clinical mood disorders, such as bipolar (manic-depressive) illness, there is a loosened connection between environmental reality and internal brain functions underlying mood.