There actually was one piece of exciting news besides the soccer World-Cup this week! Hackjin Kim and colleagues (in the lab of John O'Doherty) have published in PLoS Biology that the relief after the offset of pain activates the same brain areas as reward does (New Scientist, ScienceDaily). They found that neural activity increased in a region previously implicated in encoding stimulus reward value, the medial orbitofrontal cortex, not only following receipt of reward, but also following successful avoidance of an aversive outcome. This work was done using an operant conditioning protocol. The results are reminiscent of a study in the fruit-fly Drosophila in which my good friend Bertram Gerber and his colleagues used a classical conditioning paradigm to show that the offset of a noxious stimulus appears to have rewarding effects.
However, subsequent and yet unpublished studies revealed that this effect is independent of the well-studied reward system which relies on octopamine in the fly. So there is a disparity in the results here that could be explained in a number of ways. One of these explanations is especially interesting. It may be that the reward system is only engaged if the offset of pain is brought about by your own actions (i.e., operant) and is not engaged if you're not the reason for the ending of the pain (i.e., classical). This would reflect the notion that having control over your environment is inherently rewarding, especially if you use this control to avoid aversive stimuli.