Abstract
INTRODUCTION: To survive, an organism must remember occurrences of value in its environment. These include those that pose a threat to survival, novel or unexpected stimuli, or a general class of stimuli that represent punishment or reward. There is substantial evidence that memory for novel and emotionally salient events is enhanced relative to familiar or emotionally neutral events. METHODS: We present human functional magnetic resonance imaging (fMRI) experiments that address the neurobiological processes underlying upregulation of memory for novel or emotional events. RESULTS: Enhanced memory for novel or unexpected stimuli is mediated by anterior hippocampus, whereas increased memory for emotional stimuli is mediated by a beta-adrenergic-dependent modulation of amygdala-hippocampal interactions. We introduce a hypothesis that medial temporal connectivity with autonomic control centres may be central to this memory enhancement. CONCLUSION: Enhanced memory for stimuli that are of adaptive importance to survival is mediated by the anterior medial temporal lobe and effected via connections with the autonomic system.