The good, the bad and the amygdala

This is the title of a brief review by Ruth Williams in Nature Reviews Neuroscience pointing out an article by Paton et al. that demonstrates that in monkeys the values associated with visual stimuli are represented in the amygdala, a structure involved in reinforcement learning. Individual amygdala neurons apparently code for either "good" or "bad" . When a visual stimulus that was initially paired with a positive reward was switched to being paired with a negative reward, more that half of the responding amygdala neurons showed a switch in activity that correlated with changes in behavior, and some individual neurons showed value-specific activity. This work further confirms that the amygdala is a key brain structure in the representation of the learned value of visual stimuli.