The accurate measurement of fear memory in Pavlovian conditioning: Resolving the baseline issue.
Fear conditioning has become an indispensable behavioral task in an increasingly vast array of research disciplines. Yet one unresolved issue is how conditional fear to an explicit cue interacts with and is potentially confounded by fear prior to tone presentation, referred to as baseline fear. After tone-shock pairings, we experimentally manipulated baseline fear by presenting unpaired shocks in the testing chamber and then analyzed the accuracy of common methods for reporting tone fear. Our findings indicate that baseline fear and tone fear tend to interact, where freezing to the tone increases as baseline fear increases. However, the form of interaction is not linear across all conditions and none of the commonly used reporting methods were consistently able to eliminate the confounding effects of baseline fear. We propose a methodological solution in which baseline fear is reduced to very low levels by first extinguishing fear to the training context and then pre-exposing to the testing context.
Jacobs
Nathan S
NS
Department of Psychology, University of California, Los Angeles, Los Angeles, CA 90095, USA. nathanj@uci.edu
Cushman
Jesse D
JD
Fanselow
Michael S
MS
D000161:Acoustic Stimulation; D000704:Analysis of Variance; D000818:Animals; D035843:Biomedical Research / Q000379:methods*; D003214:Conditioning, Classical; D003463:Cues; D004597:Electroshock; D005239:Fear; D008297:Male; D008568:Memory; D051379:Mice; D008810:Mice, Inbred C57BL; D009483:Neuropsychological Tests; D013997:Time Factors
J Neurosci. 1995 Nov;15(11):7548-64
7472506
Annu Rev Psychol. 1997;48:573-607
9046569
Science. 2009 Sep 4;325(5945):1258-61
19729657
Nat Rev Neurosci. 2002 Feb;3(2):122-31
11836520
Science. 1992 May 1;256(5057):675-7
1585183
Hippocampus. 2002;12(5):578-84
12440573
Neuron. 2000 Feb;25(2):473-80
10719900
Eur J Neurosci. 2005 Jul;22(1):201-11
16029210
Science. 2007 Apr 20;316(5823):457-60
17446403
Behav Neurosci. 2002 Dec;116(6):947-57
12492293
J Comp Physiol Psychol. 1961 Aug;54:428-32
13683658
Nature. 2002 Aug 1;418(6897):530-4
12152079
J Neurosci. 2006 Aug 23;26(34):8702-6
16928858
Psychol Rev. 2007 Jul;114(3):759-83
17638505
Science. 2009 May 15;324(5929):951-5
19342552
Science. 2007 Aug 31;317(5842):1230-3
17761885
Nature. 1997 Jul 31;388(6641):471-4
9242405