Neuromodulatory basis of emotion

The neural basis of emotion can be found in both the neural computation and the neuromodulation of the neural substrate that mediates behavior. I review the experimental evidence showing the involvement of the hypothalamus, the amygdala, and the prefrontal cortex in emotion. For each of these structures, I show the important role of various neuromodulatory systems in mediating emotional behavior. Generalizing, I suggest that behavioral complexity is caused partly by the diversity and intensity of neuromodulation and hence depends on emotional contexts. Rooting the emotional state in neuromodulatory phenomena allows for its quantitative and scientific study and possibly its characterization.