TY - JOUR
T1 - Chronic stress has lasting effects on improved cued discrimination early in extinction
AU - Judd, Jessica M.
AU - Smith, Elliot A.
AU - Kim, Jinah
AU - Shah, Vrishti
AU - Sanabria, Federico
AU - Conrad, Cheryl D.
N1 - Funding Information:
The authors gratefully acknowledge the contributions of Amanda Acuña, Bryce S. Badaruddin, Eshaan J. Daas, Megan E. Donnay, Diego Padilla-Garcia, Aaron Flegenheimer, Elizabeth Hanson, Brittany Le, Logan Martin, Kenji J. Nishimura, Dylan N. Peay, Cindy Reynolds, Hovhannes Michael Saribekyan, Rujuta Takalkar and Gillian Thornton, Iva Vracar, and Christopher Willis. We are also especially appreciative to the Arizona State University Department of Animal Care and Technology for their exemplary care for the animals used in these experiments. This work was funded in part by The College, Liberal Arts and Sciences, and Knowledge Enterprise Development at Arizona State University (Conrad) and the Department of Psychology Enhancement Award at Arizona State University (Judd).
Publisher Copyright:
© 2020 Judd et al. This article is distributed exclusively by Cold Spring Harbor Laboratory Press for the first 12 months after the full-issue publication date (see http://learnmem.cshlp.org/site/misc/terms.xhtml). After 12 months, it is available under a Creative Commons License (Attribution-NonCommercial 4.0 International), as described at http://creativecommons.org/licenses/by-nc/4.0/
PY - 2020/8
Y1 - 2020/8
N2 - Chronic stress typically leads to deficits in fear extinction when tested soon after chronic stress ends. Given the importance of extinction in updating fear memories, the current study examined whether fear extinction was impaired in rats that were chronically stressed and then given a break from the end of chronic stress to the start of fear conditioning and extinction. Male rats were chronically stressed by restraint (6 h/d/21 d) and tested soon (termed immediate, STR-IMM), or 3 or 6 wk after a rest period from restraint (termed rest or “R,” STR-R3, STR-R6). In Experiment 1, STR-R3 and STR-R6 discriminated between the cue and nonshock context better than STR-IMM or control. Interestingly, STR-IMM showed high freezing to the nonshock context. Consequently, Experiment 2 investigated whether STR-IMM generalized across contexts, which was not supported. Experiment 3 determined whether STR-IMM were susceptible to second-order conditioning to a novel context, but showed that the level of second-order conditioning was similar for all groups. These findings reveal that rats exposed to chronic stress and then given a rest period of 3 or 6 wk, express unique fear extinction profiles compared to control and STR-IMM. Specifically, STR-R demonstrated excellent cue and context discrimination during extinction, and perhaps showed a stress inoculation effect. For STR-IMM, the heightened freezing under these extensive acclimation parameters was not attributed to generalization nor to second-order fear conditioning to “safe” contexts and, instead, may reflect hypervigilance.
AB - Chronic stress typically leads to deficits in fear extinction when tested soon after chronic stress ends. Given the importance of extinction in updating fear memories, the current study examined whether fear extinction was impaired in rats that were chronically stressed and then given a break from the end of chronic stress to the start of fear conditioning and extinction. Male rats were chronically stressed by restraint (6 h/d/21 d) and tested soon (termed immediate, STR-IMM), or 3 or 6 wk after a rest period from restraint (termed rest or “R,” STR-R3, STR-R6). In Experiment 1, STR-R3 and STR-R6 discriminated between the cue and nonshock context better than STR-IMM or control. Interestingly, STR-IMM showed high freezing to the nonshock context. Consequently, Experiment 2 investigated whether STR-IMM generalized across contexts, which was not supported. Experiment 3 determined whether STR-IMM were susceptible to second-order conditioning to a novel context, but showed that the level of second-order conditioning was similar for all groups. These findings reveal that rats exposed to chronic stress and then given a rest period of 3 or 6 wk, express unique fear extinction profiles compared to control and STR-IMM. Specifically, STR-R demonstrated excellent cue and context discrimination during extinction, and perhaps showed a stress inoculation effect. For STR-IMM, the heightened freezing under these extensive acclimation parameters was not attributed to generalization nor to second-order fear conditioning to “safe” contexts and, instead, may reflect hypervigilance.
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U2 - 10.1101/LM.051060.119
DO - 10.1101/LM.051060.119
M3 - Article
C2 - 32669387
AN - SCOPUS:85088156580
SN - 1072-0502
VL - 27
SP - 319
EP - 327
JO - Learning and Memory
JF - Learning and Memory
IS - 8
ER -