Memory Task Induces a Shift in Lateralization of Amygdala Response to Affective Pictures
Neuroimaging research in emotion regulation reveals a decrease of amygdala response to affective stimuli when the stimuli are perceived during the performance of a cognitive task. Two types of tasks are usually used to investigate this effect: one distracts attention from the emotional content of stimuli and another directly addresses the emotional content, such as identification of the emotional facial expression. The present fMRI study tested the effect of a third type of task: a memory task that promotes attraction of one’s attention to the emotional stimuli, but does not directly address the emotional content. A total of 44 volunteers were randomly assigned to one of two groups. In the MRI scanner, participants in the experimental group were asked to memorize emotional and neutral images taken from the IAPS (International Affective Picture System) database. Their recognition memory was subsequently tested after the scanning. Participants in the control group passively viewed the same picture set. The ROI analysis of the BOLD signal change revealed a leftward asymmetry of amygdala activation during the passive viewing of the pictures and a rightward shift of activation induced by the memory task. Results from the control ROIs demonstrated the phenomena of “inattentional deafness” in the auditory cortex and functional asymmetry in the visual cortex. The results are discussed in terms of complex functional connections between the amygdala, sensory cortices, and frontal regions of the brain.