No abstract

To understand how the human amygdala contributes to associative learning, it is necessary to differentiate the contributions of its subregions. However, major limitations in the techniques used for the acquisition and analysis of functional magnetic resonance imaging (fMRI) data have hitherto precluded segregation of function with the amygdala in humans. Here, we used high-resolution fMRI in combination with a region-of-interest-based normalization method to differentiate functionally the contributions of distinct subregions within the human amygdala during two different types of instrumental conditioning: reward and avoidance learning. Through the application of a computational-model-based analysis, we found evidence for a dissociation between the contributions of the basolateral and centromedial complexes in the representation of specific computational signals during learning, with the basolateral complex contributing more to reward learning, and the centromedial complex more to avoidance learning. These results provide unique insights into the computations being implemented within fine-grained amygdala circuits in the human brain.

A stimulus, by virtue of its pairing with a rewarding or an aversive outcome, can acquire motivating properties reflecting that outcome. However, there is uncertainty concerning the extent to which such properties might be carried across contexts. In the current study we sought to determine whether conditioning-dependent motivational properties can transfer from a computer game to the real world and, further, whether this conditioning might be expressed in terms of brain responses measured using functional magnetic resonance imaging (fMRI). We studied healthy participants conditioned with aversive and appetitive drinks in the context of a virtual cycling race. Three days after conditioning, participants returned for a fMRI session. We took this opportunity to observe the impact of incidental presentation of conditioned stimuli on a real-world decision (seat choice). We found a significant influence of conditioning on seat choice and, moreover, noted that individual susceptibility to this influence was reflected in differential insula cortex responses during subsequent scanning. The choice was also predicted by participants' personality scores and, as a statistical trend ( p ϭ 0.07), by their sense of immersion in the game environment. Our data show that motivational properties of stimuli can transfer from the virtual to the real world. While much concern has been expressed over the impact of virtual experience on general levels of aggression and mood, our data point to another important consideration: the fact that a stimulus in the virtual environment can acquire motivational properties that persist and modify behavior in the real world.