Sex Differences In Learning Research Articles

Perinatal BPA exposure demasculinizes males in measures of affect but has no effect on water maze learning in adulthood

Bisphenol A (BPA) is an endocrine disrupting agent that can alter the normal gonadal steroid-sensitive sexual differentiation of the brain and behavior. While reproductive behavior and physiology are known to be altered by perinatal exposure to this compound, less is known about BPA's effects on sex differences in learning and measures of affect. In order to evaluate the effects of perinatal BPA treatment on learning and affect in adulthood, we exposed rats to one of five doses of BPA through gestation and lactation then examined adult behavior in the Morris Water Maze (MWM), the Elevated Plus Maze (EPM) and the Forced Swim Test (FST). No effect of BPA was observed in the MWM, but on both the EPM and FST, low doses (5μg/kg) of BPA eliminated sex differences found between controls; furthermore, a non-monotonic dose–response observed in previous studies was confirmed for these tasks. Overall, our study adds to the growing data suggesting that BPA interferes with the normal development of affective behaviors in a non-linear, dose-dependent manner.

Sex differences in science learning: Closing the gap through animations

Males traditionally outperform females on measures of both visuospatial ability and science achievement. This experiment directly tests a manipulation designed to compensate for such differences through the presentation of relevant illustrations or animations to support the construction of understanding of a specific scientific phenomenon. Males and females read a scientific text about plate tectonics that contained static illustrations, animated versions of the static illustrations, or no illustrations. Participants were assessed on their visuospatial ability and also working memory capacity. Results indicated that while males outperformed females on both the visuospatial measure and overall science learning, the presence of animations effectively eliminated performance differences for this science topic. These results suggest that sex differences in learning outcomes can be overcome by supporting the visualization of scientific phenomena.

Sex differences in learning processes of classical and operant conditioning

Males and females learn and remember differently at different times in their lives. These differences occur in most species, from invertebrates to humans. We review here sex differences as they occur in laboratory rodent species. We focus on classical and operant conditioning paradigms, including classical eyeblink conditioning, fear-conditioning, active avoidance and conditioned taste aversion. Sex differences have been reported during acquisition, retention and extinction in most of these paradigms. In general, females perform better than males in the classical eyeblink conditioning, in fear-potentiated startle and in most operant conditioning tasks, such as the active avoidance test. However, in the classical fear-conditioning paradigm, in certain lever-pressing paradigms and in the conditioned taste aversion, males outperform females or are more resistant to extinction. Most sex differences in conditioning are dependent on organizational effects of gonadal hormones during early development of the brain, in addition to modulation by activational effects during puberty and adulthood. Critically, sex differences in performance account for some of the reported effects on learning and these are discussed throughout the review. Because so many mental disorders are more prevalent in one sex than the other, it is important to consider sex differences in learning when applying animal models of learning for these disorders. Finally, we discuss how sex differences in learning continue to alter the brain throughout the lifespan. Thus, sex differences in learning are not only mediated by sex differences in the brain, but also contribute to them.

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

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.

Associative learning enhances the survival of new neurons in the male and female hippocampus

Event Abstract Back to Event Associative learning enhances the survival of new neurons in the male and female hippocampus Christina Dalla1, 2* and Tracey J. Shors2 1 Medical School, University of Athens, Department of Pharmacology, Greece 2 Rutgers University, Department of Psychology and Centre for Neurosciences, United States Two decades ago, it was discovered that certain areas of the adult brain give birth to new neurons, a phenomenon called adult neurogenesis. Research in animals has shown that many of these new cells die within a few weeks, unless the animals learn certain types of complex tasks or are living in an enriched environment. Studies from our lab have shown that new cells in the hippocampus, a brain region involved in learning and memory, are more likely to survive if the animals learn a type of task that is difficult to learn. Specifically, learning during an associative task, which depends on the hippocampus (i.e. trace eyeblink conditioning), increases the survival of new cells that were generated in the hippocampus one week before the training experience [1, 2]. On the other hand, training with delay conditioning, which does not depend on the hippocampus and it is easier to learn, does not enhance the survival of the new cells. This phenomenon was first described for male rats, but it was recently confirmed in females [3]. Interestingly, females learn better than males when they are trained to associate stimuli across time, such as during the trace eyeblink conditioning task. As a consequence, more new neurons per unit volume remain in their hippocampus than in males. Furthermore, in individual animals of both sexes, the number of surviving cells correlates positively with asymptotic performance; those that express more learned responses retain more new neurons. However, animals that learn very well retain even more new cells if they require many trials to do so. Once rescued from death, most of the new cells differentiate into neurons, which become functionally integrated into the existing circuitry of the hippocampus. These new cells might be important for new learning experience or for memory. Furthermore, data on males and females suggest that sex differences in learning can contribute to structural sex differences in the adult brain. This work was supported by National Institutes of Health and National Science Foundation grants to T. J. Shors and a Marie Curie International Fellowship to C. Dalla, within the 6th European Community Framework Programme.

Sex differences in learning and inhibition in spontaneously hypertensive rats

Few studies have addressed potential differences in the nature of cognitive impairment observed in males and females with ADHD. In Experiment 1, we examined sex differences in conditioned inhibitory behaviour in spontaneously hypertensive rats (SHR strain), a purported animal model of ADHD. Rats were presented with two types of trials during each of the 15 conditioning sessions. On some trials an auditory stimulus (a tone) was presented and followed immediately by delivery of food reward. On the remaining trials the tone was preceded by presentation of a visual stimulus and on those trials food was not delivered after the tone was presented. As training progressed, conditioned responding during presentation of the tone increased on reinforced trials and decreased during the non-reinforced trials, indicative of successful discrimination and inhibition. Overall, female SHR rats exhibited less conditioned overall food cup behaviour compared to male rats. Female SHR rats also required more training sessions until they responded significantly more during presentation of the tone on reinforced trials versus non-reinforced trials. In addition, the magnitude of the discrimination was smaller in female SHR rats compared to males. In contrast, no sex differences were observed in WKY rats (commonly-used control strain) in Experiment 2. Importantly, there were no significant sex differences in baseline activity or motivation during either experiment, indicating that performance differences could not account for the observed results. These results suggest that male and female SHR rats differ in their ability to form conditioned associations and inhibit behavioural responses and may provide a useful model for sex differences in cognitive dysfunction specific to ADHD.

Erratum: corrigendum: Sex differences in learning in chimpanzees

Erratum: corrigendum: Sex differences in learning in chimpanzees

Sex differences in learning in chimpanzees

The wild chimpanzees in Gombe National Park, Tanzania, fish for termites with flexible tools that they make out of vegetation, inserting them into the termite mound and then extracting and eating the termites that cling to the tool. Tools may be used in different ways by different chimpanzee communities according to the local chimpanzee culture. Here we describe the results of a four-year longitudinal field study in which we investigated how this cultural behaviour is learned by the community's offspring. We find that there are distinct sex-based differences, akin to those found in human children, in the way in which young chimpanzees develop their termite-fishing skills.

Learning during stressful times.

Stressful life events can have profound effects on our cognitive and motor abilities, from those that could be construed as adaptive to those not so. In this review, I discuss the general notion that acute stressful experience necessarily impairs our abilities to learn and remember. The effects of stress on operant conditioning, that is, learned helplessness, as well as those on classical conditioning procedures are discussed in the context of performance and adaptation. Studies indicating sex differences in learning during stressful times are discussed, as are those attributing different responses to the existence of multiple memory systems and nonlinear relationships. The intent of this review is to highlight the apparent plasticity of the stress response, how it might have evolved to affect both performance and learning processes, and the potential problems with interpreting stress effects on learning as either good or bad. An appreciation for its plasticity may provide new avenues for investigating its underlying neuronal mechanisms.

Estrogen-mediated effects on depression and memory formation in females

Women are twice as likely to suffer from depression as men. It has been proposed that the ovarian hormones estrogen and progesterone contribute to the higher incidence of this potentially debilitating disorder. Depression can also be accompanied by a loss of cognitive performance. Here we review estrogen-mediated effects on depression and memory formation in females. We propose that changes in levels of estrogen are associated with sex differences in learning as well as changes in affect prior to menses, immediately after pregnancy and during perimenopause and the menopausal transition. Finally, we discuss the animal model of depression known as ‘learned helplessness’ and describe research from our laboratory demonstrating that exposure to an acute stressful experience compromises a female’s later ability to acquire certain types of new memories. This response to stressful experience is opposite to that observed in males and is dependent on the presence of estrogen, and more specifically—changing levels of estrogen. This observation indicates that females and males can use different hormonal and neural mechanisms to respond to the same emotional event and underscore the importance of studying the unique and changing biology of females, especially when considering treatment strategies for depression and stress-related illness.

Gender vs. Sex Differences: Factors Affecting Performance in Geographic Education

Much has been written about sex differences in learning, but less attention has been paid to the impacts of gender—which is socially constructed—on learning geography. This article investigates whether differences in gender influence performance on a standardized test of geography knowledge. Undergraduate students in two large clases completed a standardized inventory of gender differences and then completed a standardized test of geography knowledge. The results of our analysis of the correlation between gender traits and geographic learning resulted in somewhat unexpected results, as well as a set of complex questions for further research on learning styles in geographic education.

Sex differences in vicarious trial-and-error behavior during radial arm maze learning

We investigated sex differences in VTE behavior in rats during radial arm maze learning. Females made more VTEs than males, although there were no sex differences in learning. Further, VTEs and errors were positively correlated during the latter testing sessions in females, but not in males. This sex difference may be a reflection of differences between the sexes in conflict behavior or cognitive strategy while solving the maze.

Efficacy Outcome and Sex Difference in Learning of Hypermedia Programming Skills

86 occupational therapy students participated in a 20-hr, training course in hypermedia programming for selecting functions for development of rehabilitation software. Analyses showed that the training program significantly enhanced their self-efficacy in development of software for clinical practice. The students generally showed a positive attitude towards the feasibility and significance of applying hypermedia programming in occupational therapy, but no significant sex difference in programming self-efficacy was found.

■ REVIEW : Stress and Sex Effects on Associative Learning: For Better or for Worse

It is clear that male and female animals have distinct cognitive capacities and emotional responses. For instance, exposure to a fearful and stressful event of restraint and intermittent tail-shocks impairs instru mental learning in male rats, but has minimal consequence in female rats. Conversely, exposure to a similar stressor facilitates classical conditioning in male rats and dramatically impairs conditioning in female rats. Many such sex differences in learning and responses to stress are attributable to the effects of sex hormones on brain morphology and physiology. Indeed, the stress-induced facilitation of classical conditioning in male rats is dependent on activation of the NMDA type of glutamate receptor in the amygdala, whereas the impaired conditioning in female rats is dependent on activational influences of the ovarian hormone estrogen. The role of estrogen and progesterone in the diametrically opposed effects of stress on learning are dis cussed, as are neuronal mechanisms that underlie sex differences in memory formation. NEUROSCIENTIST 4:353-364, 1998

Stress facilitates classical conditioning in males, but impairs classical conditioning in females through activational effects of ovarian hormones.

Exposure to restraint and brief intermittent tailshocks facilitates associative learning of the classical conditioned eyeblink response in male rats. Based on evidence of sex differences in learning and responses to stressful events, we investigated sexually dimorphic effects of a stressor of restraint and intermittent tailshock on classical eyeblink conditioning 24 h after stressor cessation. Our results indicate that exposure to the acute stressor had diametrically opposed effects on the rate of acquisition of the conditioned response in male vs. female rats. Exposure to the stressor facilitated acquisition of the conditioned response in males, whereas exposure to the same stressful event dramatically impaired acquisition in females. We further demonstrate that the stress-induced impairment in female conditioning is dependent on the presence of ovarian hormones. Conditioning of stressed sham-ovariectomized females was significantly impaired relative to the unstressed controls, whereas conditioning in stressed ovariectomized females was not impaired. We present additional evidence that estrogen mediates the stress-induced impairment in female acquisition. Females administered sesame oil vehicle and then stressed were significantly impaired relative to their unstressed controls, whereas females administered the estrogen antagonist tamoxifen prior to stress were not impaired. In summary, these results indicate that exposure to the same aversive event can induce opposite behavioral responses in males vs. females. These effects underscore sex differences in associative learning and emotional responding, and implicate estrogen in the underlying neuronal mechanism.

Sex differences in learning and memory in mice: Effects of sequence of testing and cholinergic blockade.

Sex differences in learning and memory in mice: Effects of sequence of testing and cholinergic blockade.

Sex differences in learning and memory in mice: effects of sequence of testing and cholinergic blockade.

Sexual dimorphism in spatial and cued navigation using the Morris water maze was examined in C57BL/6 mice both with and without administration of scopolamine, a cholinergic blocker. In Exp. 1, female and male mice learned to perform first a spatial, then a cued, navigation task. Both performed a spatial task similarly; males, however, performed a cued task better than females. In Exp. 2, the sequence of navigation testing was reversed. Both performed similarly on a cued task; however, males performed a spatial task better than females. In both experiments, females were more sensitive than males to the effects of scopolamine. No significant confounding sex differences were found in either spontaneous activity or passive avoidance retention. These data indicate that sex differences in spatial and cued tasks are dependent on the sequence of task presentation and implicate a role for the cholinergic system in these differences.

Sex‐Related Differences in Adult Language Learning: Socialization and Memory Factors

which it is presented. For example, women attach great importance to expressing themselves verbally and men value facility with visual and spatial information--all socially sanctioned gender-appropriate behaviors learned by the respective gender groups. The school environment sheds further light on a broad scope of socialization experiences germane to sex differences in learning: role models, promotion of one gender group over another in specific discipline areas, and the importance attached to test-taking. All these social forces influence achievement to some

Sex differences in appetitive learning of mice

Learning abilities of male and female ddY mice were compared in two appetitive tasks (a lever-press task and an 8-arm radial maze task), and two avoidance tasks (a shuttle box task and a light-dark discrimination T-maze task). In the two types of appetitive learning, male mice were significantly superior to female mice. Sex differences were particularly apparent in the acquisition process. In contrast, there was no significant sex difference in learning of the two avoidance tasks. A sex difference in appetitive learning was not found in juvenile mice prior to sexual maturation, and the mice which had established a lever-press response as juveniles did not show any significant difference in the performance level when tested as adults. Thus, a sex difference appeared only in the acquisition stage of adult mice. These results suggest that there exists a sex difference in motivation level for hunting food but not for feeding, and that it causes a sex difference in appetitive learning.

Sex Differences in Learning Connected Discourse as a Function of Exposure and Interitem Intervals

Learning of connected discourse was contrasted for males and females for differing exposure and interitem intervals. With total presentation time constant, it was more difficult for males to learn the material when the interitem interval was greater than the exposure interval rather than the reverse. Females appeared to learn equally well under both conditions.