The effect of arousal on the emotional memory network depends on valence

Abstract

Some suggest that arousal is the essential element needed to engage the amygdala. However, the role of arousal in the larger emotional memory network may differ depending on the valence (positive, negative) of the to-be-remembered information. The goal of the current study was to determine the influence of arousal-based changes in amygdalar connectivity for positive and negative items. Participants were shown emotional and neutral pictures while they underwent a functional magnetic resonance imaging (fMRI) scan. The emotional pictures varied by valence (positive or negative) and arousal (high or low). Approximately 90minutes later, outside of the scanner, participants took a surprise recognition test. Effective connectivity analysis examined how arousal affected successful encoding activity. For negative information, arousal increased the strength of amygdala connections to the inferior frontal gyrus and the middle occipital gyrus, while for positive information arousal decreased the strength of these amygdala efferents. Further, while the effect of arousal on memory for positive information was restricted to amygdalar efferents, arousal had a more widespread effect for negative items, enhancing connectivity between other nodes of the emotional memory network. These findings emphasize that the effect of arousal on the connectivity within the emotional memory network depends on item valence.

Figure 1

Anatomical model for the effective connectivity analysis of negative items. Arrows represent anatomical connections used in the model based on known primate and rodent neuroanatomy. Connections that are significantly different between the two arousal conditions are in blue. All connections were significantly different in this model. For Talairach coordinates of peak voxels see Table 1. L=Left, IFG = Inferior Frontal Gyrus, Amyg = Amygdala, HC = Hippocampus, Fusi = Fusiform, MOG = Middle Occipital Gyrus.

Figure 2

Anatomical model for the effective connectivity analysis of positive items. Arrows represent anatomical connections used in the model based on known primate and rodent neuroanatomy. Connections that are significantly different between the two arousal conditions are in green. For Talairach coordinates of peak voxels see Table 1. L=Left, IFG = Inferior Frontal Gyrus, Amyg = Amygdala, HC = Hippocampus, Fusi = Fusiform, MOG = Middle Occipital Gyrus.