Abstract
Using event-related functional magnetic resonance imaging (fMRI) on 14
human subjects, we investigated the hypothesis that unconscious processing of emotions can take place, and that this process is driven by visual cues in the low spatial frequencies. Furthermore we investigated the role of the amygdala in a hypothesised subcortical pathway designated for rapid emotional processing. Participants viewed “hybrid” faces that either showed a fearful expression in the lowest spatial frequencies (1-8 cycles/image) and a neutral expression in the rest of the bandwidth, or “hybrids” that showed a neutral expression in the lowest spatial frequencies and a fearful expression in the rest of the bandwidth.
Contrary to our initial hypothesis we found increased activation in the amygdala when participants viewed hybrids containing explicit fear, compared to when they viewed hybrids containing implicit fear. In addition we found increased activation of the fusiform face area (FFA), and the precentral gyrus for the same comparison. These results are interpreted in the light of the existence of a distributed cortical network involved in processing of emotions. Other possible explanations for our findings are also discussed.