Dissociable Temporal Lobe Activations during Emotional Episodic Memory Retrieval

Abstract

The richness of human recollective experience is, in part, related to evocation of previously experienced emotions. An extensive functional neuroimaging literature has provided a description of brain regions involved in retrieving emotionally neutral episodic memories. Whether similar or distinct systems are involved in retrieving emotional memories is unresolved. This question motivated the present functional neuroimaging study, using 0–15 positron emission tomography (PET), where we compared patterns of brain activation associated with retrieving previously studied emotional and neutral pictorial material. By varying task requirements and item density we characterized two distinct neural response patterns during emotional memory retrieval. First, we identified an anterior temporal pole activation that reflected the psychological set associated with emotional memory retrieval. Second, we identified a left amygdala response sensitive to actual retrieval of emotional items. These data suggest distinct functional roles for temporal lobe regions during emotional memory retrieval involving context-related tonic anterior temporal pole activation and a phasic item-related amygdala response. We conclude that brain regions involved in episodic memory retrieval reflect not only physical attributes of stimulus material, for example, their verbal or visual qualities, but also their affective significance.