NEUROANATOMICAL SUBSTRATES OF EMOTIONAL MEMORY IN HUMANS

University Of Iowa, Iowa City IA

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Abstract

DESCRIPTION (Applicant's abstract): This revised FIRST Award builds on the principal investigator's previous work on emotion, and takes advantage of the unique resources provided by the Department of Neurology at the University of Iowa. The proposed studies aim at elucidating the neural systems responsible for emotional memory in humans. The phrase "emotional memory" refers to the modulation of long-term memory by the emotional state of the subject at the time stimuli are encoded. This issue is of importance in the study of memory, because it addresses the critical question of selectivity: why are some events more memorable than others? Neutral, pleasant, and unpleasant audiovisual stimuli will be shown to subjects. Memory for the stimuli will be assessed 24 hours later with free recall tasks, verbal and visual recognition memory tasks, and by measuring autonomic responses to previously seen stimuli. Two main hypotheses will be tested with two complementary methods. 1) Amygdala, ventral prefrontal cortex, and right somatosensory cortices are hypothesized to modulate memory by emotion. This hypothesis will be tested with the lesion method, by comparing memory performances between control subjects and subjects with lesions in target structures specified in the hypothesis. 2) GABAergic and beta-adrenergic neurotransmitter systems are hypothesized to modulate memory by emotion. This hypothesis will be tested with pharmacological manipulation, by comparing within-subject performances with or without specific drugs. It is predicted that normal subjects will remember best those stimuli that they found the most emotional, but that there will be specific impairments in memory for emotional stimuli in brain-damaged subjects who have lesions in target structures, and in normal subjects who have been given pharmacological agents. The results will inform strategies for the treatment of patients with disorders of emotion and memory, such as those caused by stroke, anxiety, and depression, and will contribute to our understanding of traumatic memories and eyewitness testimony.