Many emotional and behavioral dysfunctions, such as bad decisionmaking (http://dx.doi.org/10.1093/brain/awg177), appear to be symptoms of impaired brain functioning. Conversely, stimulating brain functionality alleviates these dysfunctions. For example, electric stimulation of the vagus nerve decreases depression (source).
How can brain functioning be stimulated through neuroelectrical, neurochemical and neurosurgical means?
I am interested in general answers as well as in answers specifically addressing
- the ventromedial prefrontal cortex,
- the amygdala, and
- the insular cortex,
which, according to the Somatic Marker Hypothesis, might make up the mechanism behind emotional intelligence.