The Journal of Neuroscience, November 1, 2002, 22(21):9502-9512
Electrophysiological Responses in the Human Amygdala Discriminate
Emotion Categories of Complex Visual Stimuli
Hiroyuki
Oya,
Hiroto
Kawasaki,
Matthew A.
Howard III, and
Ralph
Adolphs
Departments of Neurology and Neurosurgery, University of Iowa
College of Medicine, Iowa City, Iowa 52242
The human amygdala has been shown to participate in processing
emotionally salient stimuli related to threat, danger, and aversion,
data that have come primarily from functional imaging and lesion
studies. Recording intracranial field potentials from five amygdalas in
four patients with chronically implanted depth electrodes, we analyzed
responses in the gamma frequency range, a region of the power spectrum
thought to reflect especially the contribution of neuronal activity to
cognitive processes. Significant changes in the power amplitude of
responses were obtained selectively to visual images judged to look
aversive but not to those judged to look pleasant or neutral. Several
possible confounds were addressed: all four patients had been carefully
selected so that the amygdalas from which recordings were obtained were
distal to epileptogenic foci, making it likely that we recorded from
healthy tissue, and the observed responses could not be attributed to
luminance or color differences between the stimuli. A further analysis
of differences in power between the high and low gamma bands revealed
an additional structure that discriminated those stimuli related to
bodily injury from those related to disgust. Despite the increased
power amplitude in the gamma range, there was no stimulus-locked phase
coherence. The observed responses in the gamma frequency range may
reflect the role of the amygdala in binding perceptual representations of the stimuli with memory, emotional response, and modulation of
ongoing cognition, on the basis of the emotional significance of the stimuli.
Key words:
amygdala; human; intracranial recording; local field
potential; gamma oscillation; emotion
Copyright © 2002 Society for Neuroscience 0270-6474/02/22219502-11$05.00/0
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