Amygdala-prefrontal cortex connectivity increased during face discrimination but not time perception.

Time sensitivity is affected by emotional stimuli such as fearful faces. The effect of threatening stimuli on time perception depends on numerous factors, including task type and duration range. We applied a two-interval forced-choice task using face stimuli to healthy volunteers to evaluate time perception and emotion interaction using functional magnetic resonance imaging. We conducted finite impulse response analysis to examine time series for the significantly activated brain areas and psycho-physical interaction to investigate the connectivity between selected regions. Time perception engaged a right-lateralised frontoparietal network, while a face discrimination task activated the amygdala and fusiform face area (FFA). No voxels were active with regard to the effect of expression (fearful versus neutral). In parallel with this, our behavioural results showed that attending to the fearful faces did not cause duration overestimation. Finally, connectivity of the amygdala and FFA to the middle frontal gyrus increased during the face processing condition compared to the timing task. Overall, our results suggest that the prefrontal-amygdala connectivity might be required for the emotional processing of facial stimuli. On the other hand, attentional load, task type and task difficulty are discussed as possible factors that influence the effects of emotion on time perception.