Overall, there is considerable evidence that variation in levels of 5HT in areas of the PFC, and therefore of levels of DA in the amygdala – OFC pathway, are associated with variation in ill-advised, rash, or risky acts. It may therefore be the case that this source of individual differences in the operation of this brain system creates conditions facilitative of the emergence of individual differences in positive and negative urgency. Certain gene polymorphisms appear to relate to variability in 5HT and DA levels; because they may therefore contribute to the neurotransmitter and brain system variability we have described, we consider them next.
