Reward Loss as Psychological Pain

This article reviews research that suggests parallels between the mechanisms underlying physical pain and fear, and those underlying psychological pain derived from reward loss. Reward loss is a major source of emotional arousal and conflict that can be modeled in the laboratory in a preparation known as consummatory successive negative contrast (cSNC). In cSNC, a group of rats is exposed to a downshift in the incentive value of a sucrose solution that leads to a sharp suppression of consummatory behavior. Research reviewed in this article demonstrates that the opioid system is normally engaged in cSNC and that individual differences in sensitivity to opioid antagonists correlate with fast recovery (resilience) and slow recovery (vulnerability) from reward loss. The co-option of the opioid system into playing a role in adjustment to situations involving psychological pain may be an evolutionary adaptation unique to mammals.