Neurobiology of learning and memory
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Neurobiol Learn Mem · Oct 2010
Randomized Controlled TrialCortisol enhances neural differentiation during fear acquisition and extinction in contingency aware young women.
Previously, we observed cortisol induced enhancement of neural fear acquisition in women. Yet, less is known about cortisol effects on neural fear extinction. Via differential fear conditioning, we explored cortisol effects on acquisition and extinction. ⋯ During acquisition group differences were due to higher responses to the CS+ than to the CS- in the cortisol group. Notably, during extinction, group differences were due to higher responses to the CS- than to the CS+ in this group. Thus, cortisol induced a fear acquisition and extinction specific enhanced neural differentiation.
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Neurobiol Learn Mem · Oct 2010
Chronic stress, cyclic 17β-estradiol, and daily handling influences on fear conditioning in the female rat.
Chronic stress and estrogens alter many forebrain regions in female rats that affect cognition. In order to investigate how chronic stress and estrogens influence fear learning and memory, we ovariectomized (OVX) female Sprague-Dawley rats and repeatedly injected them (s.c.) with 17β-estradiol (E, 10 μg/250 g or sesame oil vehicle, VEH). Concurrently, rats were restrained for 6 h/d/21 d (STR) or left undisturbed (CON). ⋯ Female rats remained gonadally-intact since E did not influence tone fear conditioning. Indeed, brief daily handling (1-3 m/d/21 d) facilitated acquisition of fear conditioning in chronically stressed female rats, and either had no effect or slightly attenuated fear conditioning in controls. Thus, chronic stress impacts amygdala-mediated fear learning in both OVX- and gonadally-intact females as found previously in males, with handling significantly influencing these outcomes.