Rapid amygdala responses during trace fear conditioning without awareness.
The role of consciousness in learning has been debated for nearly 50 years. Recent studies suggest that conscious awareness is needed to bridge the gap when learning about two events that are separated in time, as is true for trace fear conditioning. This has been repeatedly shown and seems to apply to other forms of classical conditioning as well. In contrast to these findings, we show that individuals can learn to associate a face with the later occurrence of a shock, even if they are unable to perceive the face. We used a novel application of magnetoencephalography (MEG) to non-invasively record neural activity from the amygdala, which is known to be important for fear learning. We demonstrate rapid (∼ 170-200 ms) amygdala responses during the stimulus free period between the face and the shock. These results suggest that unperceived faces can serve as signals for impending threat, and that rapid, automatic activation of the amygdala contributes to this process. In addition, we describe a methodology that can be applied in the future to study neural activity with MEG in other subcortical structures.
Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
Nicholas L
NL
Balderston
Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
Douglas H
DH
Schultz
Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America; McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Qc, Canada.
Sylvain
S
Baillet
Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America; Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America.
Fred J
FJ
Helmstetter
D000293:Adolescent; D000328:Adult; D000679:Amygdala / Q000502:physiology*; D001364:Awareness / Q000502:physiology*; D001931:Brain Mapping; D003214:Conditioning, Classical / Q000502:physiology*; D003243:Consciousness / Q000502:physiology; D004597:Electroshock; D005239:Fear / Q000502:physiology*; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D010775:Photic Stimulation; D055815:Young Adult