LEHRER: You've studied some of the brain differences underlying different types of grief, and found that, paradoxically, extreme grief is actually characterized by the activation of "reward centers" in the brain. Could you explain the data? And what can this teach us about the nature of grief?
LIEBERMAN: In this study, headed by Mary-Frances O’Connor [of the University of California at Los Angeles], we looked at two groups of women whose mothers or sisters had died from breast cancer in the past few years. One group had gone through the grief process and recovered relatively normally (normal grief) and the other group was diagnosed with “complicated grief,” meaning that they were not recovering with the passage of time. Both groups were shown images and words meant to remind them of the deceased (along with control images and words that did not). Both groups showed activity in the pain network that we previously observed during social exclusion.
When we compared the two groups with one another, however, there was no difference in the activity in the pain network. Instead, we observed greater activity in a reward region (ventral striatum) in the complicated grief subjects relative to the normal grief subjects. This is the first study to find this effect so any interpretation is preliminary. Nevertheless, this activation may reflect something like a craving for connection with the deceased much like the craving for a drug in an addicted individual. To this end, we found that the activity in this same “reward” region was significantly associated with the extent to which subjects told us they were yearning for the deceased. It also reminds us that activity in the reward regions of the brain may not always signal greater well-being for an individual. Indeed, from a Buddhist perspective, these attachments and cravings gets us into just as much trouble as the more obviously negative events we all try to avoid.
LEHRER: You've found that the ability to accept unfair offers requires the activation of cortical areas typically associated with self-control. What can this teach us about our propensity for fairness?
We don’t know if accepting unfair offers “requires” lateral prefrontal activations, but we did see these activations when people did accept a certain kind of unfair offer. [Psychologist] Alan Sanfey [of Princeton University] and colleagues published the first fMRI study of the ultimatum game in 2003. In this game, the proposer decides how to split $10 between himself and the responder, and the responder decides whether to accept or not. The interesting part of the game is that if the responder says no, both players get nothing. When the proposer offers $5, an even split, responders nearly always accept, but when the proposer offers $1 or $2, the responder will often decline—even when the proposer and responder will never play the game again making reputational concerns irrelevant. Sanfey found that responders receiving unfair offers of $1 and $2 out of $10 had greater insula activity, a limbic region associated with pain and visceral distress. Moreover, greater activity in this region was associated with a greater tendency to reject the “unfair” offer.
We conducted a similar study in my lab, headed by Golnaz Tabibnia, in which we looked at two things. First, is there an observable effect of being treated fairly, above and beyond the higher monetary payouts associated with fairness? We looked at this by comparing offers such as $5 out of $10 to offers such as $5 out of $23. In both cases, you can earn $5, but the first offer is much fairer than the second. We found that when we took the monetary aspect out of the picture in this way, we still saw activity throughout the brain’s reward network, associated with being treated fairly. This [finding] is consistent with a number of recent studies showing that positive social treatment from others activates reward regions.