Modulations of emotional attention and spatial attention on human visual cortical activities

Background: Spatial attention could enhance the neural activities of attended locations in human visual cortex. As a salient stimulus, emotional image could enhance the responses in amygdala and visual areas. However, few studies examined the interaction of the attentional effects induced by emotional stimuli and spatial cues on the neural responses in visual areas. Methods: In the present study, we used functional magnetic resonance imaging (fMRI) to examine the combined and separated effects of emotional image and spatial cue on the activities in human visual areas. A revised Posner cueing paradigm was utilized. Each participant viewed a fearful image and a peaceful image simultaneously in left and right visual fields. A spatial cue of two dots was then presented in one of the image positions. In this manner, the attentional effects for emotional image and spatial cue could be isolated and combined. Results: The results showed that spatial cue enhanced the responses in V4, intraparietal sulcus (IPS) and lateral occipital area (LO), while emotional image could enhance the responses in V3, V4 and LO. Importantly, no significant interactions were found in any of the visual areas. Conclusion: Our results indicate that the two kinds of attentional modulation might not be affected by each other. These findings shed light on the neural mechanism of the emotional attention.