Research Digest The Neurobiology of Reward, Aggression and Pain

Schultz, W. (1999), The reward signal of midbrain dopamine neurons.  News in Physiological Science,  14:  249-255.

Schultz, W. (2001), Multiple reward signals in the brain.  Nature Neuroscience Reviews,  1:  199-207. Many of us working in neuropsychoanalysis have found much to learn from the work of Jaak Panksepp—whose text (Affective Neuroscience) has become something of a “bible” for those with an interest in the neurobiology of affect. One of Panksepp's core findings is the importance of the so-called “SEEKING” system: whose basis relies on mesocortical-mesolimbic dopamine. Panksepp has especially stressed (unlike other researchers) that this system is not a simple “reward” system—but rather that it rewards the investigation of “novelty” in the world, as captured by Panksepp's previous (though cumbersome) label of the “curiosity-interest-expectancy” system. The work of Wolfram Schultz appears to have demonstrated the way in which such a “novelty-reward” system might be designed—and the papers above review a decade of his group's work of single-cell recordings in primates. Schultz's work demonstrates that dopamine function in this system increases for anticipated, but not for unanticipated rewards; and that dopamine function is depressed when anticipated rewards do not arrive. Thus, the system does not code reward per se, but for the difference between expected and actual reward. Thus, it is in the animal's (including humans, of course) interest to seek out novel experiences, unanticipated pleasures, and presumably new ways of thinking about and understanding the world. It also means, for the pessimists amongst us, that those who expect little from the world are likely to find pleasure on those rare occasions when things do go according to plan. It is gratifying to see support for Panksepp's account of neurobiology of emotion—especially in relation to this above all other emotion systems, given that the SEEKING system is a likely candidate for the biologi