From lowering stress levels to improving your memory, these are the 10 ways sex affects your brain. During sexual activity, a flood of feel-good hormones are released throughout our bodies, lighting up the reward centers in our brains. Like dopamine, oxytocin is produced by the. This review focuses on the study of sex differences in the neurobiology of social behavior, memory, emotions, and recovery from brain injury, with particular. A micrograph shows isolated neurons from the brain of a human fetus. In infancy, about half the neurons will die during a pruning period.
Humans, like other mammals, exhibit sex differences in their brains and psychological traits. But what do they signify? We ask experts to explain what happens in the brain when you have sex and how this affects your decision-making, as well as your body. If you haven't heard, it's sex month on the site! We wanted to kick off a month of sex talk with a little science and whole lot of kindness. Reproductive.
This review focuses on the study of sex differences in the neurobiology of social behavior, memory, emotions, and recovery from brain injury, with particular. Humans, like other mammals, exhibit sex differences in their brains and psychological traits. But what do they signify? We ask experts to explain what happens in the brain when you have sex and how this affects your decision-making, as well as your body.
Sharing personal information brings people closer together. Verified by Psychology Today. Hive Mind. Imagine brain you admire—morally and politically. To the decent treatment of all, to kindness as the guide to interactions with others.
Now, imagine this person coming across a surprising fact in a neuroscience or brwin textbook. They look up from the book, their faces ashen. Realizing that their lives up until now have been based on a lie, they stalk the earth, repudiating their earlier exhortations to treat one another as equals. Their eloquence and passion brings followers in their wake. Followers who had sex been treating their neighbor as themselves, giving back good for evil, and consistently fighting for social justice.
Not now. Now these previously decent people call for segregation. Internment of the deviant. Even darker things. Such a vision is grotesque. And, I put it you, if you find braain absurd that previously decent people could upend their lives and repudiate their morals on the basis of a contingent probably contentious and highly technical scientific claim then this is because it is absurd.
Do your moral codes rest on such contingent brain claims? Does your decent treatment of your fellows hang by such a rbain thread? Gawd sex the rest of us if you open the wrong book at the wrong time…. Saying that people deserve to be treated decently is not a factual claim.
People have been either succeeding or more often failing to treat each other kindly, fairly, and honorably, since before there was science, since before there were people really. And—they will continue to try and often fail far into the future, whatever science reveals about our natures. All the foregoing seems blindingly obvious. Both are trying to argue that humans are neurological hermaphrodites, as if somehow admitting braiin sex differences in brains would mandate the unfair treatment of women.
It is tempting to rebunk these debunkings but, if I am right in my guess about what is going on here, no amount of factual piling on is going to help. Fine and Rippon have decided that women are often not treated fairly.
We almost all agree rbain this. But they have decided that the way to counter unfairness, sex to claim that men and women sex neurologically identical. Nature recently penned an anguished rebuttal to its earlier review in support of Rippon. All of that factual back-and-forth is important although it must be danged confusing to non-specialists watching from the sidelines but, if my guess is right this is going to brain Rippon et al.
By the sacred jockstrap of Jordan Peterson, I did not know that! Now get into that kitchen and make me a sammich! Less facetiously, they have become confused by the fact that, historically bigots, have and still do take weird factual claims about sex differences morally seriously, and come to the conclusion that brain way to address this is to attack those claims.
They will find new reasons, invent them if they have to, and ignore the whole of science if they must. You can see brain doing all these things right now. Why does this matter? Because failing to treat sex differences as real means that things like drug dosages, disease susceptibility, and differential diagnoses, are being swept under the carpet. Sexual dimorphism does not mean that males and females are different in every respect. It means that sex is a meaningful variable that allows us to predict differences.
Brain differences. Go and look at that list I made below. And consider what would have to be true for sexual dimorphism not to apply to brains. It would mean rbain an entire chromosome, which has about genes on the X bit, and 70 on the Y, has no effect on braon resultant organism and its control center. Evolution couldn't work that way. Their bodies are different.
Not as different as some sexually dimorphic species—but different nonetheless. Brains control bodies. For those brains to be indistinguishable, would be like saying sex any TV remote should sex all other TVs. Of course, there are similarities—more similarities than differences—but braiin this is the really important point sex So what? Put it this way: What systematic brain difference would mandate treating half the human population as brain to the other half? Name one. I dare you. I double dare you.
For males to find females attractive, they sex to be attracted to female-typical bodies. For females to find males attractive, they have to be attracted to male-typical bodies. Now, let me say this slowly and carefully, these are not the same bodies. However, if recent experience is anything to go by, simply elucidating facts is not going to stop this daftness sex away.
What might make it go away is if we brain do better at treating each other fairly and decently. And doing that is a lot harder than having an ideology.
A partial list of reliable and robust sex-based brain differences all showcased in the January Journal of Neuroscience Research. Bear in minds that most of these are meta-analyses, summaries of dozens sometimes hundreds of other studies. Thanks, Dr. King, well said. I once heard an equal rights advocate state that people of all race, sex, sexual orientation, etc. I think your focus on treating each other fairly is right on.
As a feminist myself, Sx cannot understand for the life of me why some people and extreme feminists are out there trying to prove that we're the same. We are not. But that doesn't mean we should be treated inferiorily. Every man and woman, and everyone in between, has a right to live life as they see fit, regardless of their differences, which are undeniable. One is not better or lesser than another. They simply are. I wish more people understood that.
Maybe if they did we could end this silly debacle that only serves to divert our energy from things that really matter, like finding a way to get ourselves out of this horrible climate issue we've dug ourselves into Thansk for your brin. Somehow the idea that equality requires identity has crept into some minds.
But a few minutes reflection would suggest that one reason that humans value each other is precisely becuae they are not identical to each other. Its not just an issue of diversity although that matters too.
Its that each human is unique and irreplaceable. Wouldn't the notion that their brains are different than the healthy population have political implications? And it does, right? I mean, George Conway has been accusing Trump of having brain P.
Some of the work we do here are UCC is abotu acquired brain injury and one braih brain things that students who work with folk with ABI rapidly learn is compassion for the fragility of humans. To talk of illness or neurological atypicality is to approach things brai the perspective of accident or misfortune though. No-one is seriously suggesting in our culture at least that people are unlucky to jy women or unlucky to be men and by virtue of that should brzin be treated as fully human.
People have spoken that way and alas still do in some parts of the world. But not here. Childrens brains are not fully formed either and thats why in part we dont allow them full access to the responsibilities that adults have. But we dont need to know anything much about brains to realize that. Cultures have been seeing children as children since long before brain science came along.
As for things like personality disorders: Well, these are deep waters. For one thing, a lot of mental health professionals are uncomfortable desginating somethign as a disease something you have when its arguably something you are. Whatever the truth of that, individuals will vary in talents, abilties, and suitablity for office.
But none of that means that they aren't fully human. But none of that applies to adult brains, does it? Interesting question, and I think the answer is that as far as mental illness and politics, the gender differences don't really pertain to mental illnesses in a straightforward way.
The biggest difference in terms of politics and policy that makes sense would seem to be with regard to physical size and strength, such as in sports, though even that difference, on average, isn't all that great. Certainly, historically, the physical and mental differences between men and women are much smaller than was thought years ago!
As for Trump, he's obviously a narcissist and clearly fits the description on almost all points in the DSM. I think they call that a personality disorder, which isn't all that uncommon.
Given this evidence that males and females use different ERs in different parts of the synapse to influence neurotransmitter release, it is possible that the cellular and molecular mechanisms through which estradiol regulates memory differ between the sexes. Preliminary data from the Frick laboratory suggest this may be true, at least in mice. For example, we have found that a post-training dorsal hippocampal infusion of estradiol enhances object recognition and object placement memory consolidation in gonadectomized and gonadally-intact male mice, as it does in ovariectomized mice Koss and Frick, Table 1.
However, unlike in females, estradiol infusion does not increase ERK phosphorylation in males Koss and Frick, , nor does inhibiting ERK phosphorylation prevent estradiol from enhancing memory consolidation in males, suggesting that estradiol may trigger different cell-signaling pathways to enhance memory in males and females Table 1. Although the identity of these pathways is not yet known, this is an active area of investigation. Although the scant data cited in this paragraph suggest the intriguing possibility of sex differences in the molecular mechanisms through which estrogens regulate memory formation, considerably more study is needed to definitively support this conclusion.
Stroke is a cerebrovascular disease caused by interruption of the blood supply to the brain, resulting in rapid death of neurons and, consequently, a range of neurological problems including loss of sensory or motor function, paralysis, depression, dementia, epilepsy, and even death. Stroke is the 5th leading cause of death and leading cause of disability in the United States Mozaffarian et al.
A principal variable affecting stroke incidence in aging is the biological sex of the patient. Women are more likely to get a stroke Petrea et al. In fact, the rates of stroke-related death have declined over the last 25 years for men but not for women Silva et al. Furthermore, because women live longer than men, it is projected that stroke-related disability and institutionalization is likely to affect women more than men Lai et al.
Although not studied systematically, existing data on preclinical and transitional therapies suggests that there may be sex-specific effects of stroke neuroprotectants and therapies. Tissue plasminogen activator tPA; Alteplase is the only FDA-approved therapy for stroke, and its mode of action consists of proteolytic degradation of the clot, with the goal of re-establishing circulation, known as recanalization.
However, towards the end of the study period, sex differences in the use of IV tPA were eliminated Towfighi et al. Nevertheless, sex-biased therapy persists, as shown in a recent study where women were more likely to be excluded from tPA for hypertension as compared to men, suggesting that under-treatment of stroke risk factors in women may further impact stroke therapies as well Madsen et al.
Although several drugs have been identified in preclinical studies, only a few of these have made it to clinical trials and none have succeeded Chacon et al. Whereas several reasons may explain why the preclinical promise of these drugs was not borne out in clinical trials, in at least one case tirilazad mesylate , European trials showed the outcomes were much worse in women as compared to men Tirilizad Steering Committee, Preclinical studies with these drugs routinely failed to use clinically-relevant animal models, such as aged subjects, or include females and those with comorbid diseases van der Worp et al.
These and other studies provided the impetus for the STAIR recommendations, which specifically recommends the use of clinically-relevant animal models in studies of stroke Fisher et al.
Sex differences in stroke outcome are also well recognized in preclinical models summarized in Table 3. Specifically, young females rats and mice have a smaller infarct volume and better cerebral blood flow than age-matched males both in normoglycemic Alkayed et al.
Although young females sustain a smaller infarct than young males or aged female mice or rats Selvamani et al. In fact, these age effects may be accelerated in females, such that middle aged female rats show worse stroke outcomes than adult female rats, whereas adult and middle-aged males do not differ Selvamani and Sohrabji, In contrast, gonadectomy in males reduces infarct volume, suggesting that testosterone, the precursor steroid for estradiol, may be neurotoxic Yang et al.
Surprisingly, estradiol treatment reduces infarct volume in both younger males and females Toung et al. Thus, while availability of estrogens is likely the reason for sex differences in infarct severity in young animals, estradiol treatment is protective for both sexes at this age. Similarly, the peptide hormone, insulin-like growth factor IGF -1, is also neuroprotective in both males and older females.
These are among the handful of preclinical factors that have been studied in both sexes, where a similar outcome has been observed. In many other instances, studies have shown unexpected sex differences in outcome. Stroke-related cell death and recovery is multi-factorial, and preclinical studies have, therefore, focused on cell death modulators, immune modulators, and compounds that facilitate recovery through neurogenesis and angiogenesis. The following paragraphs will describe sex differences that have been reported for stroke outcomes using compounds that modulate the inflammatory response and cell death pathways.
Minocycline, a tetracycline antibiotic, represents an excellent example of sex differences in the effects of anti-inflammatory therapy. Minocycline is known to cross the blood—brain barrier, and once in the brain, can attenuate neuronal apoptosis, reduce the inflammation response by reducing microglial activation and migration of T-cells, and inhibit matrix metalloproteinase-9, which remodels extracellular matrix Yrjanheikki et al.
In experimental models of acute ischemic stroke, minocycline shows neuroprotective effects and improved behavioral outcomes in young adult males Yrjanheikki et al.
However, in studies where both male and female mice were included, Li and McCullough reported that minocycline is effective in reducing infarct volume only in male mice. Furthermore, minocycline was also ineffective in ovariectomized female mice, even though male and ovariectomized female mice presented similar levels of estrogens Table 3 Li and McCullough, This paradox was also noted in the clinical literature.
Early clinical trials for minocycline showed improved outcomes in the treatment group Lampl et al. However, a study by Kohler and colleagues showed that intravenous minocycline treatment given to stroke patients was safe but not efficacious Kohler et al. More recently, an open-label evaluator-blinded trial found that oral minocycline mg daily for 5 days was effective when male and female data were compiled together Amiri-Nikpour et al.
However, when the data were analyzed separately for males and females, male patients showed significantly lower improved NIH stroke scale NIHSS in the minocycline-treated group compared with controls, whereas no significant clinical improvement was seen in female patients relative to control groups Amiri-Nikpour et al. Emerging data suggest that cell-death pathways in ischemic stroke are sexually dimorphic Reeves et al.
Cell death can result from activation of caspase-dependent and caspase-independent pathways. Studies show that females are more susceptible to caspase-dependent cell death, whereas males are more susceptible to caspase-independent cell death. As a result, compounds that target only one of these pathways display profound sex differences in their efficacy summarized in Table 3. These pathways are discussed briefly below. Poly ADP-ribose polymerase-1 PARP-1 activation is a major cytotoxic pathway and plays a key role in the pathogenesis of cardiovascular and inflammatory diseases Beneke, ; Peng et al.
In the previously discussed study Li and McCullough, , Li et al. However, a novel water-soluble PARP-1 inhibitor, MP, was shown to ameliorate stroke-induced neurological deficits and brain infarct volume in both male and female monkeys Matsuura et al.
Preclinical studies show that reducing nNOS via targeted deletion or by pharmacological inhibitors reduces ischemia-induced cell death Yoshida et al. However, these studies were performed only on young adult? Female nNOS null mice exhibit a worse outcome after middle cerebral artery occlusion MCAO relative to wild-type females, whereas the absence of nNOS in male null littermates produces a better outcome compared to wild-type males, suggesting that neurotoxicity of NO production is restricted to males.
Sex steroids may also play a role in the effects of NO. Estradiol, present in both males and females, promotes protection of endothelial function and vascular reactivity dilation by enhancing endothelial e NOS functionality and NO production, and manipulating endothelium-derived hyperpolarizing factor EDHF effectivity.
However, testosterone has opposing effects, increasing cerebrovascular inflammation and cerebral artery tone Krause et al. These findings confirm the hypothesis that ischemia induced cell death is more reliant on the NO-PARP pathway in males, whereas the NO pathway may play a beneficial role in females. Although caspase pathways are activated in both sexes after stroke, caspase-dependent cell death pathways are more amenable to treatment in females as compared to males Siegel et al.
Caspase-dependent cell death can be initiated by extrinsic death receptor mediated or intrinsic mitochondria mediated factors.
In the case of ischemia, formation of reactive oxygen species stimulate the release of mitochondrial cytochrome-c to the cytosol.
Subsequent formation of the apoptosome, which includes the apoptotic protease activating factor Apaf -1, cytochrome c and caspase-9, cleaves procaspase to caspase-3, an executioner caspase. Caspase-3 then cleaves cellular substrates that induce biochemical features of apoptosis, including DNA fragmentation Cai et al.
In ischemic studies, the pan-caspase inhibitor, quinoline-Val-Asp Ome -CH2-O-phenoxy Q-VD-OPh , shows neuroprotective effects in both neonatal and adult female mice when administered after stroke, but has no effects in males Renolleau et al. Interestingly, pan caspase inhibitors are effective in females that are gonadally intact or ovariectomized Liu et al.
A new class of stroke therapies comes from epigenetic regulators, including histone modifiers and non-coding RNA. Compounds that promote histone acetylation, such as HDAC inhibitors, reduce stroke-associated disability in males and females Langley et al. Of these, miRNAs have been most comprehensively studied. MiRNAs are predicted to control tissue- and cell-specific transcriptomes Krek et al.
MiRNA cohorts can change rapidly after acute injury such as stroke, and are actively being studied for their possible role as stroke biomarkers. MiRNA profiles are altered with stroke, both in humans Liu da et al. Plasma levels of miR17 are reported to be significantly elevated in acute stroke patients Kim et al.
MiRNAs have also been shown to mediate neuroprotection in stroke models. Specifically, inhibitors of Let7f, mir-1 Selvamani et al. Most miRNAs have only been studied in one sex typically male , but in a few instances where both sexes were studied, unexpected differences were noted in efficacy of these compounds, as discussed below.
First discovered in C. Let7f has regulatory roles in a wide variety of gene families, including oncogenes, genes related to cell cycle and differentiation, apoptosis, and immunity. Among the genes targeted by Let7f for translational suppression is IGF-1, a potent stroke neuroprotectant in males and females reviewed in Sohrabji, Antagonists to Let7f decreased infarct volume in adult females, and improved post-stroke behavioral impairment Selvamani et al.
Paradoxically, anti-Let7f elevated stroke-related disability in middle-aged females and had no effect on ovariectomized females or males Selvamani et al Although the precise explanation underlying the age- and sex-dependent effects of this miRNA are not known, one cautionary note is that each miRNA regulates dozens of genes; some of these genes may have benign effects and others less so.
Thus, elevated levels of this miRNA during age may not only suppress translation of IGF-1, but also suppress other genes that may exacerbate stroke disability.
Mirp was identified as a potential neuroprotectant based on a comprehensive profiling of serum miRNA. This approach capitalized on the well-known age and sex differences in seen in experimental stroke studies, where adult females typically sustain the smallest infarction compared to age-matched males and middle-aged males and females Selvamani et al.
Mirp expression was found to be inversely correlated with infarct volume Selvamani et al. To assess the functional significance of elevated mirp, adult females were injected with mirp antagonists after stroke.
This treatment resulted in increased stroke-induced infarction in a group that typically has small stroke-induced infarction, and increased motor disability as compared to controls that received a scrambled oligo. Reciprocally, middle-aged females were injected with mirp mimics, and this treatment reduced stroke-related infarction and motor disability. Remarkably, although males at both ages had lower levels of mirp, intravenous injections of the mimic did not affect stroke outcomes in either group.
A well-validated target of mirp is caspase-3, a cell death effector protein, and in females, the mirp mimic effectively decreased caspase-3 expression and activity, whereas no regulation of this protein was seen in males Selvamani and Sohrabji, This finding is consistent with evidence from other caspase-inhibiting compounds see above that have also failed to show neuroprotection in males.
Although the molecular mechanisms that make caspase-3 more tractable for stroke in females but not in males are not clearly understood, it should be recognized that estradiol and testosterone have very different effects on caspasemediated cell death. Estradiol reduces caspase-3, however, estradiol treatment also improves stroke outcomes in males where caspase-independent cell death pathways are more critical, suggesting that caspase-mediated cell death is only one of the many ways in which this hormone promotes stroke recovery Suzuki et al.
In contrast, testosterone exacerbates stroke-induced cell death, and has increases caspase-mediated cell death in a cell-specific manner Cunningham et al. The sex difference in caspase-dependent cell death pathways underscores the importance of studying both sexes while new therapies are devised for acute neural diseases. The relatively scarce use of both sexes in preclinical stroke therapy studies may be a critical factor in the lack of success in translating preclinical work to clinical practice.
Even though aged women have a higher risk for stroke, worse outcomes, and poorer recovery after ischemia compared to aged men, preclinical studies have routinely failed to utilize clinically relevant animal models e. Sex differences in morphology, physiology, and behavior are common across the animal kingdom, and are driven and maintained by evolutionary processes that lead to the existence of different proximal mechanisms that govern phenotype in males and females. The prevalence of diverse types of sex differences across multiple species has profound implications for the ways in which researchers must approach behavioral, neurobiological, and biomedical investigations.
We have presented here a review of studies in different areas of behavioral neuroscience illustrating sex differences in multiple aspects of behavior, including the ways in which animals relate to conspecifics and learn about their environment, as well as the underlying neurobiological underpinnings of these behaviors. Importantly, this review highlights a critical implication of these sex differences, namely that they form the foundation for sex differences in the risk, severity, and presentation of disease, thus precipitating the need for sex-specific treatments that address the disease as it presents uniquely in each sex.
This situation is exemplified by stroke, where sex differences in risk and symptomology lead to sex biases in treatment and disparate efficacies of many stroke treatments in men and women. The literature reviewed here also demonstrates that sex hormones play an important role in the determination and modulation of sex differences. This male bias is attributed, in part, to the protective role played by estrogens in females and also to the toxic effects of testosterone.
Both hypotheses receive some support from evidence that oophorectomized females surgical menopause have a high incidence of PD that is equal to men Benedetti et al. In fact, testosterone has also been implicated as a risk factor for developmental neurological disease, due to a higher basal neuroinflammatory state caused by androgen from the fetal testes McCarthy, Collectively, sex differences in basic and clinical research have led to federal policy changes in the United States at the National Institutes of Health , Canada at the Canadian Institutes of Health Research and Europe the Horizon initiative that require sex be considered as a biological variable in biomedical research.
In the United States and Canada, it is not required that every proposal include both males and females, but the exclusion of one sex must be scientifically justified in each application Clayton, The purpose of this, and related policies, is to rectify the long-standing under-representation of females in biomedical research.
Such policies have been challenged on practical grounds, as it has been argued that the inclusion of both sexes increases the cost and scope of research, thereby wasting precious research resources and time e.
These practical arguments have some merit, particularly because grant budgets have not been adjusted upwards to accommodate additional subjects of the opposite sex.
Theoretical arguments against the policies suggest that sex differences in the human brain are rather minimal and pale in comparison to other differences such as species, age, or genetic variation Joel et al. This view suggests that sex as a variable does not deserve special consideration over other variables that could affect biological function, particularly in preclinical research Eliot and Richardson, A cogent counterargument for considering sex as a biological variable in preclinical research is that the purpose of this work is to understand how biological systems function, and examining function in both sexes is paramount in light of the many sex differences that have already been identified Shansky and Woolley, Moreover, the paucity of research directly examining sex differences warrants special consideration of sex in biomedical research, especially in light of the fact that sex has been long neglected as a variable in biomedical research Beery and Zucker, ; Shansky and Woolley, We agree with the perspective that findings discovered in one sex cannot be automatically extrapolated to the other sex and support the view that key results obtained in one sex should be verified in the other.
When sex differences are demonstrated or suspected e. These studies should be conducted with sufficient statistical power to allow for the effective inclusions of biological sex, hormonal condition e. For additional discussion and practical recommendations on this subject we refer the reader to recent reviews Galea et al. Sex differences in conditions like stroke warrant the development of sex-specific treatments.
If men and women are affected by stroke in considerably different ways, then why would we treat them the same?
Indeed, surgical interventions for cardiovascular disease have different outcomes in men versus women, which suggests a careful sex-biased approach to treatment of heart disease Kodali et al. We would argue that the extra effort required for the study of sex differences can pay big dividends when it comes to the understanding of the biology of disease and the development of treatment strategies that can lead to more desirable and efficacious medical outcomes in men and women.
National Center for Biotechnology Information , U. Neurosci Biobehav Rev. Author manuscript; available in PMC Feb 1. Galea , b Farida Sohrabji , c and Karyn M. Frick d. Liisa A. Karyn M. Author information Copyright and License information Disclaimer. Copyright notice. The publisher's final edited version of this article is available at Neurosci Biobehav Rev. See other articles in PMC that cite the published article. Abstract Biological differences between males and females are found at multiple levels.
Introduction Considerable interest has been directed towards understanding differences in how male and female physiology can contribute to sex differences in disease incidence, manifestation, and outcome. Brief History of the Evolution of Sex Differences Species in which two distinct cell types, the gametes, must fuse together to produce offspring i. Why Studying Evolutionary causes of Sex Differences in Traits Matters The evolutionary causes of sex differences may aid our understanding of sex differences in disease and can inform sex-targeted and sex-appropriate medical interventions.
Sex differences in rodent social behavior: hormonal influences Hormones regulate most aspects of social behavior, from reproduction and mate choices, to social cognition, social interactions, and aggression. Table 2 Sex differences in social, spatial and object-recognition learning. Open in a separate window. Social recognition: role of estrogens and androgens in male and female rodents Social recognition is a critical regulator of most social behavior.
Social learning: role of estrogens in female rodents Whereas social recognition involves learning about others and their characteristics, social learning permits animals to acquire novel adaptive information from others. Social interactions and aggression: role of estrogens and androgens in male and female rodents Males of many species typically show higher levels of overt territorial aggression i. Figure 1. Making sense of sex differences and hormonal regulation of rodent social behavior Overall, hormones, especially estrogens, are highly involved in social behavior, affecting social recognition, social learning, and social interactions in males and females.
Sex differences in pattern separation and spatial learning: relationship to neurogenesis 3. Are there sex differences in cognition? Sex differences in the hippocampus: function and neurogenesis Although there are a number of brain areas and brain networks that are implicated in cognition, the hippocampus is a widely studied area in memory research for a number of reasons. Relating sex differences in spatial ability and neurogenesis In one recent study of rats, sex differences favouring males were observed during learning of the hidden platform version of the Morris water maze, but no sex differences were observed in spatial memory probe trial performance Chow et al.
Figure 2. Molecular mechanisms underlying the regulation of memory consolidation by estradiol and progesterone As discussed above, sex differences have been reported in numerous aspects of learning and memory that are mediated, at least in part, by the hippocampus. Estrogenic regulation of one-trial object learning Numerous studies from the Frick laboratory and others have demonstrated that systemic injection or dorsal hippocampal infusion of estradiol given immediately after training i.
Cell-signaling mechanisms regulating estrogen-induced memory consolidation The rapid nature of memory formation in one-trial object learning tasks affords the opportunity to discern the molecular mechanisms that govern hormonal regulation of memory consolidation. Sex differences in molecular mechanisms underlying estrogenic memory modulation Indeed, such sex differences in response to estradiol have been documented in recent years. Sex differences in stroke and stroke therapies Stroke is a cerebrovascular disease caused by interruption of the blood supply to the brain, resulting in rapid death of neurons and, consequently, a range of neurological problems including loss of sensory or motor function, paralysis, depression, dementia, epilepsy, and even death.
Table 3 Sex differences in stroke risk and therapies. Sex differences in treatment efficacy in clinical studies Tissue plasminogen activator tPA; Alteplase is the only FDA-approved therapy for stroke, and its mode of action consists of proteolytic degradation of the clot, with the goal of re-establishing circulation, known as recanalization. Sex differences in treatment efficacy in preclinical studies Sex differences in stroke outcome are also well recognized in preclinical models summarized in Table 3.
Sex differences in anti-inflammatory therapy Minocycline, a tetracycline antibiotic, represents an excellent example of sex differences in the effects of anti-inflammatory therapy. Sex differences in cell-death pathways Emerging data suggest that cell-death pathways in ischemic stroke are sexually dimorphic Reeves et al.
Caspases Although caspase pathways are activated in both sexes after stroke, caspase-dependent cell death pathways are more amenable to treatment in females as compared to males Siegel et al. Sex differences in epigenetic modifiers A new class of stroke therapies comes from epigenetic regulators, including histone modifiers and non-coding RNA.
Let7f First discovered in C. Mirp Mirp was identified as a potential neuroprotectant based on a comprehensive profiling of serum miRNA. Summary The relatively scarce use of both sexes in preclinical stroke therapy studies may be a critical factor in the lack of success in translating preclinical work to clinical practice. Conclusions and outlook Sex differences in morphology, physiology, and behavior are common across the animal kingdom, and are driven and maintained by evolutionary processes that lead to the existence of different proximal mechanisms that govern phenotype in males and females.
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Behav Neurosci. A new approach to understanding the molecular mechanisms through which estrogens affect cognition. Biochim Biophys Acta Gen Subj. Carlen Costa , noting that melatonin has a "calming" effect on our brains. For many of us, it's easy to feel stressed out more than ever these days, between hectic work days, our home lives, social commitments, and seemingly never-ending to-do lists.
But one solid remedy is sex, as researchers have proven. Sexual activity creates a response in several areas of the brain, which is why it has so many impacts on our physical and emotional health, including acting as a natural stress reliever. A study from the Journal of Biological Psychology found that penile-vaginal intercourse helped lower blood pressure levels in men and women, lowering stress levels better than any other sexual activity.
As Costa previously told INSIDER, the release of oxytocin during intercourse also helps regulate levels of cortisol, the stress hormone, leading to a calming effect. And the increased cerebral blood flow helps our brain better process our response to anxiety. Though sex helps boost mental health in all genders, it's women who benefit most from exposure to her partner's semen.
According to a study from the University at Albany, semen eases depression in women who are not using barrier methods of protection during penetrative sex. Nearly women were screened based on their mental health and sexual behavior, and UAlbany psychology professor Gordon Gallup found that "females who engaged in sexual intercourse but never used condoms exhibited significantly lower scores" in a depression screening than "those who usually or always used condoms.
Of course, having safe sex and using protective measures against sexually transmitted infections is of the utmost importance. Though male sexual response has been extensively studied, fewer studies have been done on the effects of sexual response on the female brain.
But in , researchers at Rutgers University Newark used fMRI functional magnetic resonance imaging to examine brain activity immediately before, during, and immediately after female orgasm. The study, published in The Journal of Sexual Medicine found that brain activity was "heightened" in the moments during orgasm, with activity overall being lower during the arousal period beforehand and the recovery period afterward.
The activity level increased during orgasm in several parts of the brain, indicating that it's not just our bodies that experience heightened sensations during orgasm, but our brains as well. In , researchers at the University Medical Center Groningen in the Netherlands studied the human brain during penile sexual stimulation , finding that sexual desire before physical stimulation activated the right amygdala, triggering penile erection, sexual feelings, and sensations of pleasure.
A study from the same university — which focused on the link between male ejaculation and brain activity — found that the increase in blood flow to the cerebellum upon ejaculation also plays an important role in "emotional processing.
As we get older, brain function naturally declines, with our memories increasingly susceptible to decline the older we get. But a study by Australian researchers published in the journal Archives of Sexual Behavior found that sex could improve your memory when you're older , with results showing a direct correlation between more frequent sexual activity and memory performance.
As we move into adulthood, parenting also generates brain changes along sex-related lines. Expectant mothers spend nine months marinating in a flood of hormones that alter their brain circuitry. Once they give birth, hormones are released to stimulate lactation and to cement an emotional bond with their newborns.
For mothers, that hormone surge is part of an exquisitely choreographed internal program that nurtures developing fetuses throughout pregnancy. For fathers, the social interaction with their offspring spawns binding neural ties. One study found that when paternal mice snuggled with their newborn pups in the nest, it prompted the formation of new brain cells that created a lasting connection with their offspring. These particular brain cells are also regulated by prolactin, a hormone that orchestrates the milk production in the breasts of new mothers.
As a consequence, even when the fathers were separated from their babies for a few weeks — normally enough time to forget cage mates — they easily recognized their pups when they were reunited. But new neurons formed only if the father had physical contact in the nest with the pups.
But this has long-term implications for mental health because these social interactions yield the release of hormones that change the brain, which, in turn, forms social memories. And these memories reinforce positive social interactions, creating positive feedback loops. On the epigenetic side of the equation, research into different parenting behaviors indicates that positive experiences may become embedded in our DNA — and in a way that also breaks down along gender lines. They used 8-week-old mice and placed them into three distinct environments.
In the first group, mothers raised their litters alone until their pups were weaned; in the second, the impregnated females were put in cages with virgin females who helped them rear the young mice; and the third group consisted of pups reared by both parents.
When the young animals were successfully weaned, researchers gave them a series of tests to gauge their fear response, along with their cognitive, memory and social skills.
The mice were also injected with a dye that could illuminate the footprints of new nerve cell growth in the brain. But while male pups raised by two parents produced more gray matter in the memory-processing regions, dual-parented females sprouted twice the number of nerve cells in the corpus callosum, a thick bundle of nerve fibers that enhances communications between both sides of the brain and facilitates spatial coordination and sociability.
In fact, female mice raised by two parents were more proficient at negotiating a ladder with uneven rungs than females with just one parent — and all females were far more adept at this task than the males, even those reared by two parents.
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A micrograph shows isolated neurons from the brain of a human fetus. In infancy, about half the neurons will die during a pruning period. Newsletter Sign up for our email newsletter for the latest science news. Sign Up.
Images from a mouse study show the male brain top has many more cells in the bed nucleus of the stria terminalis, an area that regulates anxiety and response to stress. Courtesy of Nancy Forger. My Science Shop Elements Flashcards. My Science Shop Einstein's Universe. My Science Shop Observer's Handbook Shop Now. Stay Curious.