More generally, it appears to be the case that patterns of neurotransmitter activity may help explain individual differences in activity within this brain system. Both bottom-up and top-down interactions between the amygdala and the OFC appear to occur through the use of neuromodulators, such as 5HT and DA (Lewis & Todd, 2007). Therefore, to describe a mechanism by which individual differences in the activity of this system operate, and hence possibly contribute to the emergence of individual differences in urgency, we next consider key, relevant aspects of neurotransmitter functioning.
