Carter, Ronald McKell and Hofstötter, Constanze and Tsuchiya, Naotsugu and Koch, Christof (2003) Working memory and fear conditioning. Proceedings of the National Academy of Sciences of the United States of America, 100 (3). pp. 1399-1404. ISSN 0027-8424. PMCID PMC298784. http://resolver.caltech.edu/CaltechAUTHORS:CARpnas03
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Previous studies of associative learning implicate higher-level cognitive processes in some forms of classical conditioning. An ongoing debate is concerned with the extent to which attention and awareness are necessary for trace but not delay eye-blink conditioning [Clark, R. E. & Squire, L. R. (1998) Science 280, 77-81; Lovibond, P. F. & Shanks, D. (2002) J. Exp. Psychol. Anim. Behav. Processes 28, 38-42]. In trace conditioning, a short interval is interposed between the termination of the conditioned stimulus (CS) and the onset of the unconditioned stimulus (US). In delay conditioning, the CS and US overlap. We here investigate the extent to which human classical fear conditioning depends on working memory. Subjects had to carry out an n-back task, requiring tracking an item 1 or 2 back in a sequentially presented list of numbers, while simultaneously being tested for their ability to associate auditory cues with shocks under a variety of conditions (single-cue versus differential; delay versus trace; no task versus 0-, 1-, and 2-back). Differential delay conditioning proved to be more resilient than differential trace conditioning but does show a reduction due to task interference similar in slope to that found in trace conditioning. Explicit knowledge of the stimulus contingency facilitates but does not guarantee trace conditioning. Only the single-cue delay protocol shows conditioning during the more difficult working memory task. Our findings suggest that the larger the cognitive demands on the system, the less likely conditioning occurs. A postexperimental questionnaire showed a positive correlation between conditioning and awareness for differential trace conditioning extinction.
|Additional Information:||Copyright © 2003 by the National Academy of Sciences. Edited by Larry R. Squire, University of California, San Diego, CA, and approved December 6, 2002 (received for review July 9, 2002). Published online before print January 27, 2003, 10.1073/pnas.0334049100 This paper was submitted directly (Track II) to the PNAS office. We thank D. Anderson, M. Fanselow, C. J. Han, C. O’Tuathaigh, and J. R. Manns for input and assistance throughout the development of this work. This research was supported by the William T. Gimbel Discovery Fund in Neuroscience at California Institute of Technology, the Keck Foundation, the National Institute of Mental Health, and by the Engineering Research Centers program of the National Science Foundation.|
|Group:||Koch Laboratory, KLAB|
|Subject Keywords:||brain systems, awareness, amygdala, trace, acquisition, hippocampus, rats, involvement, activation, extinction|
|PubMed Central ID:||PMC298784|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||13 Dec 2005|
|Last Modified:||14 Nov 2014 19:18|
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