Research on both animals and humans clearly demonstrates that the nucleus accumbens is active

during the processing of rewards. Reward can be decomposed into “wanting” and “liking,” and elegant experimental designs have shown that the nucleus accumbens is activated when a reward is “wanted.” 46 It is the reinforcement value of the reward that is associated with nucleus accumbens activation, Inhibitors,research,lifescience,medical and not the experiential aspect of reward. To clarify, the conscious level of processing may or may not include the feeling of reward, even when an object is reinforced. In addition, correlational analyses were conducted between behavioral responses and activation in this region. Activation in the nucleus accumbens was not correlated with the amount of time that had passed since the death event, the participant’s age, or the self-reported positive/negative affect after the scan. Inhibitors,research,lifescience,medical The nucleus accumbens activation was positively correlated with self-reported yearning at an interview in the week prior

to the scan. This result does not indicate that the nucleus accumbens activation is causal Inhibitors,research,lifescience,medical in distinguishing CG and SB1518 mouse non-CG (ie, this region does not necessarily cause impaired adaptation during grief, as its higher level of activation may be a consequence of the symptoms of CG). It also doesn’t tell us if the region is related to individual differences, or whether its activation changes in intensity across adaptation. In Inhibitors,research,lifescience,medical other words, at least two possibilities exist: (i) those

with CG would show distinctive activation in this region as an individual difference – perhaps even before the loss of a loved one; (ii) all individuals may show greater activation in this region early in adaptation to a loved one’s death, and decreasing activation Inhibitors,research,lifescience,medical in this region as they adapt psychologically. In order to choose between these two explanations, future research must include multiple scans longitudinally, in order to observe change during adaptation. Finally, it is not possible to know from functional neuroimaging what neurons in the nucleus accumbens region are the sources of this increased activation. For example, this brain region is rich in oxytocin, opioid, and dopamine receptors, and neurons that use one, two, or all three of these neurotransmitters may have been more active in those already with CG than those with non-CG. Thus, future research using positron emission tomography (PET), which quantifies the levels of these neurotransmitters in the central nervous system, would be a productive avenue of research in discriminating CG from non-CG. For those with CG, reminders of the deceased activated neural reward activity, and this neural reinforcement may interfere with adapting to the loss in the present. Or, the nucleus accumbens activation may simply be a neurobiological indicator of where the bereaved is in the adaptation process.