Distinctive stress effects on learning during puberty

Hodes, Georgia E.; Shors, Tracey J.

doi:10.1016/j.yhbeh.2005.02.008

Cited by 97 publications

(91 citation statements)

References 49 publications

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“…In rats, they are most evident when females begin training in proestrus, when estrogen levels are elevated (18,20,22). In the present study, the differences in trace conditioning were not limited to stages of estrus when estrogen levels are elevated.…”

Section: Discussionmentioning

confidence: 40%

“…Adult (70 -90 days old) male (300 -350 g) and female (250 -350 g) SpragueϪDawley rats were individually housed and maintained on a 12-hour light/dark cycle. Stages of estrus were determined in female rats with daily vaginal smears, as described (20,52). Only adult females that demonstrated at least two 4 to 5 day cycles with all stages of estrus were included in the study.…”

Section: Methodsmentioning

confidence: 99%

“…The studies addressing the effects of learning on neuronal survival have been conducted exclusively in male rodents, despite evidence for sex differences in associative learning and hippocampal neurogenesis, both of which are enhanced when estrogen levels are high (18)(19)(20)(21)(22). In the present study, we asked whether sex differences in trace conditioning would be evident even when females were trained when estrogen levels are relatively low (diestrus).…”

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confidence: 93%

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Female rats learn trace memories better than male rats and consequently retain a greater proportion of new neurons in their hippocampi

Dalla

Papachristos

Whetstone

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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108

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Learning increases the survival of new cells that are generated in the hippocampal formation before the training experience, especially if the animal learns to associate stimuli across time [Gould E, Beylin A, Tanapat P, Reeves A, Shors TJ (1999) Nat Neurosci 2:260 -265]. All relevant studies have been conducted on male rats, despite evidence for sex differences in this type of learning. In the present study, we asked whether sex differences in learning influence the survival of neurons generated in the adult hippocampus. Male and female adult rats were injected with one dose of bromodeoxyuridine (BrdU; 200 mg/kg), to label one population of dividing cells. One week later, half of the animals were trained with a temporal learning task of trace eyeblink conditioning, while the other half were not trained. Animals were killed 1 day after training (12 days after the BrdU injection). Hippocampal tissue was stained for BrdU and a marker of immature neurons, doublecortin. Both sexes learned to emit the conditioned eyeblink response during the trace interval. As a consequence, more new neurons remained in their hippocampi than in sex-matched controls. In individual animals, the number of surviving cells correlated positively with asymptotic performance; those that expressed more learned responses retained more new neurons. However, animals that learned very well retained even more new cells if they required many trials to do so. Because females emitted more learned responses than males did, they retained nearly twice as many new cells per unit volume of tissue. This effect was most evident in the ventral region of the hippocampal formation. Thus, sex differences in learning alter the anatomical structure of the hippocampus. As a result, male and female brains continue to differentiate in adulthood.eyeblink conditioning ͉ learning ͉ neurogenesis ͉ sex differences ͉ stem cell

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Section: Discussionmentioning

confidence: 40%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 93%

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Female rats learn trace memories better than male rats and consequently retain a greater proportion of new neurons in their hippocampi

Dalla

Papachristos

Whetstone

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

108

View full text Add to dashboard Cite

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“…Adult (2-3 months) male (300-350 g) and female (250-350 g) Sprague-Dawley rats were individually housed with ad libitum access to food and water and maintained on a 12-h light/dark cycle. Stages of estrus were determined in female rats with daily vaginal smears, as described (Hodes and Shors, 2005;Leuner and Shors, 2006).…”

Section: General Proceduresmentioning

confidence: 99%

“…In masculinized females, there was no vaginal canalization and vaginal smears, as it happens normally in females during puberty around the postnatal day 35 (Hodes and Shors, 2005). One TP-treated female that exhibited normal vaginal canalization during puberty was excluded from the study.…”

Section: General Proceduresmentioning

confidence: 99%

Females do not Express Learned Helplessness like Males do

Dalla

Edgecomb

Whetstone

et al. 2007

Neuropsychopharmacol

151

101

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Women are more likely than men to suffer from stress-related mental disorders, such as depression. In the present experiments, we identified sex differences in one of the most common animal models of depression, that of learned helplessness. Male and female rats were trained to escape a mild footshock each day for 7 days (controllable stress). Each rat was yoked to another rat that could not escape (uncontrollable stress), but was exposed to the same amount of shock. One day later, all stressed rats and unstressed controls were tested on a more difficult escape task in a different context. Most males exposed to uncontrollable stress did not learn to escape and were therefore helpless. In contrast, most females did learn to escape on the more difficult escape task, irrespective of whether they had been exposed to controllable or uncontrollable stress. The sex differences in helplessness behavior were not dependent on the presence of sex hormones in adulthood, because neither ovariectomy of females nor castration of males abolished them. The absence of helplessness in females was neither dependent on organizational effects of testosterone during the day of birth, because masculinized females did not express helplessness as adults. Thus, sex differences in helplessness behavior are independent of gonadal hormones in adulthood and testosterone exposure during perinatal development. Learned helplessness may not constitute a valid model for depressive behavior in women, at least as reflected by the response of female rats to operant conditioning procedures after stressful experience.

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Defining age limits of the sensitive period for attachment learning in rat pups

Upton

Sullivan

2010

Developmental Psychobiology

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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-0.5mA 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.

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Distinctive stress effects on learning during puberty

Cited by 97 publications

References 49 publications

Female rats learn trace memories better than male rats and consequently retain a greater proportion of new neurons in their hippocampi

Female rats learn trace memories better than male rats and consequently retain a greater proportion of new neurons in their hippocampi

Females do not Express Learned Helplessness like Males do

Defining age limits of the sensitive period for attachment learning in rat pups

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