All that glitters ... dissociating attention and outcome expectancy from prediction errors signals

Initially reported in dopamine neurons, neural correlates of prediction errors have now been shown in a variety of areas, including orbitofrontal cortex, ventral striatum, and amygdala. Yet changes in neural activity to an outcome or cues that precede it can reflect other processes. We review the recent literature and show that although activity in dopamine neurons appears to signal prediction errors, similar activity in orbitofrontal cortex, basolateral amygdala, and ventral striatum does not. Instead, increased firing in basolateral amygdala to unexpected outcomes likely reflects attention, whereas activity in orbitofrontal cortex and ventral striatum is unaffected by prior expectations and may provide information on outcome expectancy. These results have important implications for how these areas interact to facilitate learning and guide behavior.