The amygdala, top-down effects, and selective attention to features.

While the amygdalar role in fear conditioning is well established, it also appears to be involved in a wide spectrum of other functions concerning emotional information. For example, the amygdala is thought to be involved in guiding spatial attention to emotionally relevant information such as the eye region in faces, and it gets activated differentially during different tasks. Here, we propose that the guidance of feature-based attention is the basis for the involvement of the amygdala in these seemingly disparate functions. Feature-based attention usually precedes spatial attention, and performing different tasks usually requires attending to different features. Although to date, no experiments have specifically tested the amygdalar role in feature-based attention, studies showing that the amygdala responds to simple elements, and findings of amygdalar involvement in non-spatial forms of attention hint at such a role. Our hypothesis that the amygdala guides feature-based attention builds on earlier proposals that the amygdala guides spatial attention and assesses biological relevance, but it is more specific and accounts for the failure to find amygdalar activation when spatial cues guide attention. Our hypothesis results in the testable prediction that the amygdala is involved when searching for stimuli based on their feature information, but not when searching for stimuli based on spatial cues.