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Dev Psychobiol

Title:		Defining age limits of the sensitive period for attachment learning in rat pups
Author(s):		Upton KJ; Sullivan RM;
Address:		"Department of Zoology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA. kupton@ou.edu"
Journal Title:		Dev Psychobiol
Year:		2010
Volume:		52
Issue:		5
Page Number:		453 - 464
DOI:		10.1002/dev.20448
ISSN/ISBN:		1098-2302 (Electronic) 0012-1630 (Print) 0012-1630 (Linking)
Abstract:		"Enhanced odor preference learning and attenuated fear learning characterizes rat pups' attachment learning Sensitive Period for learning the maternal odor. This period terminates at 10 days old (PN10) with increasing endogenous levels of the stress hormone, corticosterone. Increasing Sensitive Period pups' corticosterone prematurely terminates the Sensitive Period, while decreasing corticosterone in older pups delays Sensitive Period termination. Here we extend these findings and define the age range corticosterone alters learning and question whether corticosterone permanently terminates the Sensitive Period. Pups were odor-0.5 mA shock conditioned with either corticosterone increased (PN5-6; 4 mg/kg vs. saline) or decreased (PN15-16; naturally by maternal presence or corticosterone synthesis blocker, Metyrapone). Finally, PN7-8 pups were conditioned with corticosterone and reconditioned without corticosterone to assess whether the Sensitive Period was permanently terminated. Results indicate developmental limits for corticosterone regulation of pup learning are PN6 through PN15. Furthermore, inducing precocious corticosterone induced fear learning was not permanent, since reconditioning without corticosterone enabled odor preference learning. Results suggest pups are protected from learning aversions to maternal odor until approaching weaning"
Keywords:		"Amygdala/physiology Animals Animals, Newborn Association Learning/physiology Avoidance Learning/physiology Conditioning, Classical/physiology Corticosterone/blood *Critical Period, Psychological Electroshock Fear/physiology Female Male *Object Attachment;"
Notes:		"MedlineUpton, Karen J Sullivan, Regina M eng R01 DC003906/DC/NIDCD NIH HHS/ R01 DC009910/DC/NIDCD NIH HHS/ DC009910/DC/NIDCD NIH HHS/ DC003906/DC/NIDCD NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2010/06/29 Dev Psychobiol. 2010 Jul; 52(5):453-64. doi: 10.1002/dev.20448"