Because little is known about the human trait of affiliation, we provide a novel neurobehavioral model of affiliative bonding. Discussion is organized around processes of reward and memory formation that occur during approach and consummatory phases of affiliation. Appetitive and consummatory reward processes are mediated independently by the activity of the ventral tegmental area (VTA) dopamine (DA)–nucleus accumbens shell (NAS) pathway and the central corticolimbic projections of the u-opiate system of the medial basal arcuate nucleus, respectively, although these two projection (...) systems functionally interact across time. We next explicate the manner in which DA and glutamate interact in both the VTA and NAS to form incentive-encoded contextual memory ensembles that are predictive of reward derived from affiliative objects. Affiliative stimuli, in particular, are incorporated within contextual ensembles predictive of affiliative reward via: (a) the binding of affiliative stimuli in the rostral circuit of the medial extended amygdala and subsequent transmission to the NAS shell; (b) affiliative stimulus-induced opiate potentiation of DA processes in the VTA and NAS; and (c) permissive or facilitatory effects of gonadal steroids, oxytocin (in interaction with DA), and vasopressin on (i) sensory, perceptual, and attentional processing of affiliative stimuli and (ii) formation of social memories. Among these various processes, we propose that the capacity to experience affiliative reward via opiate functioning has a disproportionate weight in determining individual differences in affiliation. We delineate sources of these individual differences, and provide the first human data that support an association between opiate functioning and variation in trait affiliation. Key Words: affiliation corticolimbic-striatal networks; appetitive and consummatory reward; dopamine; oxytocin; personality; social bonds; social memory; u-opiates. (shrink)

Pain is most often an unpleasant experience that alerts us to actual or possible tissue damage. However, insisting that pain is always bad news may hinder understanding of pain’s many facets. Despite its unpleasantness – or perhaps because of it – pain is known to enhance the perceived value of certain activities, such as punishment or endurance sports. Here, we review evidence for a series of mechanisms involved in putative benefits of pain. A byproduct of pain’s attention-grabbing quality can be (...) enhanced perception of concurrent pleasurable stimuli. This is thought to explain why pain may augment the pleasure of spicy foods. By providing an aversive contrast, pain can also improve the experience of events that follow pain’s offset and lead to pleasant relief. Other potential benefits of pain derive from its ability to inhibit other unpleasant experiences and to elicit empathy and social support. The experience of pain can benefit our defence systems, since pain can enhance motivation to accumulate resources such as social support and calorie-rich foods. It can also reduce the guilt we feel after self-indulgence or moral transgressions. In sum, we highlight a series of potentially positive effects linked to pain. This framework can aid the understanding of why people sometimes seek out, enjoy, and gain rewards from pain as well as pleasure. (shrink)