ABSTRACT
This chapter takes a closer look at the neurochemistry featured in reinforcement sensitivity theory (RST) undergirding the behavioral approach system, behavioral inhibition system, and fight/flee/freeze system. Other important neurotransmitters that impact behavior such as gamma-aminobutyric acid and glutamate are also discussed, as are important hormones such as testosterone, cortisol, and oxytocin. I describe the basics of the process of neurotransmission and then move on to looking at the primary transmitter systems of RST—the serotonin, dopamine, and norepinephrine. Then I introduce the exciting idea of differential susceptibility positing that while carriers of certain alleles considered risk alleles are more susceptible to negative environmental experiences, they are also more susceptible to positive environmental experiences such that they benefit more from positive experiences than do non-carriers of the risk allele. Differential susceptibility theory is a model of biological sensitivity to environmental context positing that some individuals are more susceptible to than others to both negative (risk-promoting) and positive (development-enhancing) environmental conditions. In other words, some people are orchids who thrive particularly well in the right environment but will wilt in difficult circumstances, whereas others are dandelions that are able to adjust adequately to almost any environment but will forever be just dandelions.
