Chapter 12. Sex: Evolutionary, Hormonal, and Neural Bases

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By Emily Oster At some point or another, most books about the brain come back to the story of Phineas Gage. Gage was a railroad worker in the 19th century. In an unfortunate 1848 accident, a large steel spike was driven through his eye and out the other side of his head, taking some of his brain with him (this is the point in the story where my 8-year-old told me to please stop telling it). Amazingly, Gage survived the accident with much of his faculties intact. What did change was his personality, which, by many reports, became more aggressive and belligerent. Gage’s doctor wrote up his case, arguing that it suggested “civilized conduct” was localized in a particular part of the brain — specifically, the part he had lost. Science was off in search of where in the brain various skills were kept, with the idea that the brain was a kind of map, with little areas for, say, walking or talking or hearing or smelling. This proceeded, albeit slowly; for a while, there wasn’t much of a way to study this other than by looking at people with traumatic brain injuries. So it’s understandable that the development of technologies to study intact brains caused a lot of excitement. Generating the most discussion in recent years has been functional magnetic resonance imaging (or fMRI), which allows researchers to measure oxygen flow to the brain and identify which parts activate in response to varying stimuli. These technologies have not always lived up to the hype. The mechanics and statistics of processing fMRI imaging data have turned out to be far more complex than initially imagined. As a result there were many false claims made about which parts of the brain “controlled” different aspects of behavior or actions. The best, or at least funniest, example of this was a paper that showed how cutting-edge statistical analysis of fMRI made it possible to identify parts of the brain that responded differently to happy or sad faces. Sounds good, until you learn that the subject for this experiment was a dead fish. © 2019 The New York Times Company

Keyword: Sexual Behavior; Brain imaging
Link ID: 26594 - Posted: 09.10.2019

/ By Hope Reese In her new book “Gender and Our Brains,” cognitive neuroimaging professor Gina Rippon explains that brains aren’t gendered, but research can be. The differences among women as a group, or men as a group, are greater than the differences between men and women, Rippon says. Rippon sifts through centuries of research into supposed differences in areas such as behavior, skills, and personality, and shows that external factors like gender stereotypes and real-world experiences are the likely cause of any detectable differences in mental processing. And she demonstrates that the differences among women as a group, or among men as a group, are much greater than the differences between men and women. She cites a 2015 study looking at 1,400 brain scans as an example. Comparing 160 brain structures in the scans — identifying areas that were, on average, larger in men or in women — researchers could not find any scans that had all “male” traits, or all “female” traits — physical attributes such as weight or tissue thickness. “The images were, literally, of a mosaic,” she says. “We’re trying to force a difference into data that doesn’t exist.” Rippon teaches cognitive neuroimaging — the study of behavior through brain images — at Aston University in England. For this installment of the Undark Five, I spoke with her about how neuroimages are misinterpreted and whether PMS is real, among other topics. Here is our conversation, edited for length and clarity. Undark: Scientists have been trying to find differences in the brains of men and women for years. What are some examples of how the cherry-picking approach is problematic? Gina Rippon: It’s what I call the “hunt the differences” agenda, which started about 200 years ago when scientists were starting to understand the importance of the brain in explaining human behavior and human ability. Copyright 2019 Undark

Keyword: Sexual Behavior; Brain imaging
Link ID: 26584 - Posted: 09.07.2019

By Emily Underwood Of the many proposed triggers for autism, one of the most controversial is the “extreme male brain” hypothesis. The idea posits that exposure to excess testosterone in the womb wires both men and women to have a hypermasculine view of the world, prioritizing stereotypically male behaviors like building machines over stereotypically female behaviors like empathizing with a friend. Now, a study is raising new doubts about this theory, finding no effect of testosterone on empathy in adult men. The work does not directly address whether high levels of prenatal testosterone cause autism or lack of empathy. That would require directly sampling the hormone in utero, which can endanger a developing fetus. But the new study’s large size—more than 600 men—makes it more convincing than similar research in the past, which included no more than a few dozen participants, experts say. The extreme male brain hypothesis was first proposed by psychologist Simon Baron-Cohen at the University of Cambridge in the United Kingdom. In 2001, he and colleagues found that women given a single hefty dose of testosterone fared significantly worse at the Reading the Mind in the Eyes test (RMET), which asked them to gauge the emotional states of others based on their facial expressions. The women’s performance seemed to track with a controversial metric called the 2D:4D ratio, the relative lengths of the second and fourth fingers. Men—and people with autism—tend to have a longer ring finger than index finger, and some researchers believe that is due to higher prenatal exposure to testosterone. (Others are skeptical.) © 2019 American Association for the Advancement of Science

Keyword: Autism; Sexual Behavior
Link ID: 26571 - Posted: 09.04.2019

By Pam Belluck How do genes influence our sexuality? The question has long been fraught with controversy. An ambitious new study — the largest ever to analyze the genetics of same-sex sexual behavior — found that genetics does play a role, responsible for perhaps a third of the influence on whether someone has same-sex sex. The influence comes not from one gene but many, each with a tiny effect — and the rest of the explanation includes social or environmental factors — making it impossible to use genes to predict someone’s sexuality. “I hope that the science can be used to educate people a little bit more about how natural and normal same-sex behavior is,” said Benjamin Neale, a geneticist at the Broad Institute of M.I.T. and Harvard and one of the lead researchers on the international team. “It’s written into our genes and it’s part of our environment. This is part of our species and it’s part of who we are.” The study of nearly half a million people, funded by the National Institutes of Health and other agencies, found differences in the genetic details of same-sex behavior in men and women. The research also suggests the genetics of same-sex sexual behavior shares some correlation with genes involved in some mental health issues and personality traits — although the authors said that overlap could simply reflect the stress of enduring societal prejudice. Even before its publication Thursday in the journal Science, the study has generated debate and concern, including within the renowned Broad Institute itself. Several scientists who are part of the L.G.B.T.Q. community there said they were worried the findings could give ammunition to people who seek to use science to bolster biases and discrimination against gay people. One concern is that evidence that genes influence same-sex behavior could cause anti-gay activists to call for gene editing or embryo selection, even if that would be technically impossible. Another fear is that evidence that genes play only a partial role could embolden people who insist being gay is a choice and who advocate tactics like conversion therapy. © 2019 The New York Times Company

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 26555 - Posted: 08.30.2019

By Lindsey Bever There is no one gene that determines a person’s sexual orientation, but genetics — along with environment — play a part in shaping sexuality, a massive new study shows. Researchers analyzed DNA from hundreds of thousands of people and found that there are a handful of genes clearly connected with same-sex sexual behavior. The researchers say that, although variations in these genes cannot predict whether a person is gay, these variants may partly influence sexual behavior. Andrea Ganna, lead author and European Molecular Biology Laboratory group leader at the Institute of Molecular Medicine in Finland, said the research reinforces the understanding that same-sex sexual behavior is simply “a natural part of our diversity as a species.” The new study, published Thursday in the journal Science, is not the first to explore the link between genetics and same-sex behavior, but it is the largest of its kind, and experts say it provides one of the clearest pictures of genes and sexuality. Ganna, who is also an instructor at Massachusetts General and Harvard, and an international team of scientists examined data from more than 470,000 people in the United States and the United Kingdom to see whether certain genetic markers in their DNA were linked to their sexual behavior. Specifically, the researchers used data from the UK Biobank study and from the private genomics company 23andMe, which included their DNA data and responses to questions about sexual behaviors, sexual attraction and sexual identity. More than 26,000 participants reported at least one sexual encounter with someone of the same sex. Earlier studies, the researchers said, weren’t large enough to reveal the subtle effects of individual genes. © 1996-2019 The Washington Post

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 26554 - Posted: 08.30.2019

By Annie Roth Kalutas live fast and die young — or, at least, the males do. Male kalutas, small mouselike marsupials found in the arid regions of Northwestern Australia, are semelparous, meaning that shortly after they mate, they drop dead. This extreme reproductive strategy is rare in the animal kingdom. Only a few dozen species are known to reproduce in this fashion, and most of them are invertebrates. Kalutas are dasyurids, the only group of mammals known to contain semelparous species. Only around a fifth of the species in this group of carnivorous marsupials — which includes Tasmanian devils, quolls and pouched mice — are semelparous and, until recently, scientists were not sure if kalutas were among them. Now there is no doubt that, for male kalutas, sex is suicide. In a study, published in April in the Journal of Zoology, researchers from the University of Western Australia and the University of Queensland confirmed that kalutas exhibit what is known as obligate male semelparity. “We found that males only mate during one highly synchronized breeding season and then they all die,” said Genevieve Hayes, a vertebrate ecologist and the lead author of the study. Dr. Hayes and her colleagues monitored the breeding habits of a population of kalutas in Millstream Chichester National Park in Western Australia during the 2013 and 2014 breeding seasons. In both seasons, the researchers observed a complete die-off of males. Although male kalutas have exhibited semelparity in captivity, this was the first time it had been seen in the wild. Kalutas evolved independently of other semelparous dasyurids, so the confirmation that male kalutas die after mating suggests that this unorthodox reproductive strategy has evolved not once, but twice in dasyurids.

Keyword: Sexual Behavior
Link ID: 26552 - Posted: 08.29.2019

Patti Neighmond The pathway to opioid abuse for women often starts with a prescription from the doctor's office. One reason is that women are more likely than men to seek help for pain. Pain researchers say that not only do women suffer more painful conditions, they actually perceive pain more intensely than men do. "The burden of pain is substantially greater for women than men," says researcher and psychologist Roger Fillingim, "and that led pain researchers like myself to wonder if the pain perception system is different in women than in men." For more than two decades, Fillingim has been studying gender differences and pain, most recently at the University of Florida's Pain Research and Intervention Center of Excellence, where he is director. He recruits healthy male and female volunteers to take part in experimental pain sessions using various painful stimuli, including pressure, heat, cold and electrical stimulation. Probes are typically applied to the hand or arm. As intensity of the stimuli is increased, volunteers are asked to rate their pain on a scale of zero to 10, where zero is no pain and 10 is the most intense pain one can imagine. If volunteers report pain levels at 10, Fillingim stops the experiment immediately. "On average, women report the same stimuli to be more painful than men," Fillingim says, emphasizing that the same stimulus is applied to everybody, so if there are differences in how painful the experience is, it can't be because of the stimulus because it's calibrated to be the same for all. © 2019 npr

Keyword: Pain & Touch; Sexual Behavior
Link ID: 26546 - Posted: 08.27.2019

Ammar Kalia Three years ago, Paul (not his real name), now 31, went to the doctor with stomach pains. His blood test came back with low testosterone levels. “We went to see a urologist and he said bluntly that we wouldn’t have any options to have kids with my sperm – we would have to use a donor or adopt,” he says. “My wife immediately burst into tears.” The couple had been trying for a child since they married in 2015. Paul was also devastated. “It put so much stress on me, because I thought I couldn’t give my wife or my family what they so desperately wanted.” Eventually, Paul was diagnosed with Klinefelter syndrome. Affecting about one in 600 men, it is one of the most common genetic conditions in the UK, yet most people have never heard of it – including many who have it. Its symptoms – extra height, persistent tiredness, reduced bodily hair and small testes – can be difficult to identify, meaning it often goes unnoticed by patients and GPs. Untreated, however, it can lead to reduced testosterone and infertility, and even increased prevalence of testicular cancer. The non-hereditary syndrome was first discovered in 1942. It is caused by the presence of an extra X chromosome, resulting in XXY, as opposed to XY. With only one in six men who have Klinefelter’s ever diagnosed, even though symptoms often emerge during puberty, it may be one of the leading unexplored causes of infertility. Now, the first clinic in the UK to deal solely with Klinefelter’s has opened at Guy’s hospital in London – and its clinicians believe it could revolutionise its treatment and diagnosis. © 2019 Guardian News & Media Limited

Keyword: Sexual Behavior
Link ID: 26539 - Posted: 08.26.2019

By James Gorman Here are three good things about gulls: They are devoted parents. Males share child care equally with females. That includes sitting on the eggs during incubation. And they have figured out a way — actually many ways — to survive in a harsh and unforgiving world. Some eat clams, some eat fish, some are attracted to landfills. Of course, a few will divebomb you at the beach or boardwalk to steal a French fry, or the cheese on your cracker, or an entire slice of pizza. The beach pirate approach to survival is, of course, where humans and gulls clash. And the outcry from humans is almost as loud and outraged as the cries of the gulls themselves. Several recent news articles have chronicled the predations of gulls and some possible remedies. Ocean City, N.J., is bringing in hawks, and some scientists have suggested staring directly at gulls to fend them off. Though that is hard to do when the birds sneak up behind you as you are putting cheese on a cracker. There are some reports of more serious trouble. In England, a woman said a gull carried off her Chihuahua, and in Russia a pilot was hailed as a hero for safely landing his plane after a collision with a flock of gulls. In the New York area, thousands of birds, including gulls, have been killed in the decade since the Miracle on the Hudson crash to clear the skies for airplanes, without an apparent reduction in bird strikes. But it’s at the beach where tempers flare most predictably. And in times like these, with heightened human-gull tensions, very little has been written about the gulls’ point of view. Is there a Lorax who speaks for the gulls? Admittedly, gulls have quite a strong voice of their own, it’s just that it’s pretty unintelligible to most of us. An ornithologist would seem to be the obvious choice. They like birds. I called Christopher Elphick at the University of Connecticut. He spends a lot of time studying sparrows, but has a soft spot for gulls. © 2019 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 26537 - Posted: 08.24.2019

By Gretchen Reynolds For women with serious depression, a single session of exercise can change the body and mind in ways that might help to combat depression over time, according to a new study of workouts and moods. Interestingly, though, the beneficial effects of exercise may depend to a surprising extent on whether someone exercises at her own pace or gets coaching from someone else. Already, a wealth of recent research tells us that exercise buoys moods. Multiple studies show that physically active people are more apt to report being happy than sedentary people and are less likely to experience anxiety or depression. In a few experiments, regular exercise reduced the symptoms of depression as effectively as antidepressant medications. But science has yet to explain how exercise, a physical activity, alters people’s psychological health. Many exercise scientists speculate that working out causes the release of various proteins and other biochemical substances throughout our bodies. These substances can enter the bloodstream, travel to our brains and most likely jump-start neural processes there that affect how we feel emotionally. But it has not been clear which of the many substances released during exercise matter most for mental health and which kinds of exercise prompt the greatest gush in those biochemicals. Those open questions prompted Jacob Meyer, an assistant professor of kinesiology at Iowa State University in Ames, to start considering endocannabinoids and the runner’s high. As the name indicates, endocannabinoids are self-produced psychoactive substances, similar to the psychoactive compounds in cannabis, or marijuana. Created in many of our body’s tissues all the time, endocannabinoids bind to specialized receptors in our brains and nervous systems and help to increase calm and improve moods, among other effects. © 2019 The New York Times Company

Keyword: Depression; Sexual Behavior
Link ID: 26522 - Posted: 08.21.2019

Statistics Canada says Canadian men are almost twice as likely to use cannabis as women. New data from the National Cannabis Survey today shows 16 per cent of Canadians over 15 years old report using pot in April, May or June. That's down slightly from 17.5 per cent in the first three months of the year. Almost five million Canadians consumed cannabis in some form during the three month period. One quarter of men, and 16 per cent of women, reported they plan to consume it in the next three months. The survey suggests men are more likely to use cannabis daily or weekly than women, and are also more likely to use it for non-medicinal purposes. About four in 10 marijuana users say they bought cannabis illegally. Smoking the drug remains the most common way of consuming it, with 68 per cent of men and 62 per cent of women consumers choosing this method. At 14 per cent, women were almost three times more likely than men (five per cent) to have consumed cannabis through "other methods," including edible and topical variants. Recreational marijuana became legal in Canada last October and Statistics Canada is tracking consumption habits every three months. ©2019 CBC/Radio-Canada.

Keyword: Drug Abuse; Sexual Behavior
Link ID: 26506 - Posted: 08.16.2019

By Katie Camero For humans, slight variations in temperature don’t mean much. But for some turtles, they mean the difference between whether embryos come out male or female. Now, scientists have evidence that these embryos have some power over their sexual destiny: By moving to slightly warmer or cooler spots inside their eggs, freshwater turtle embryos can help determine their own sex. Not everyone is convinced. But if the new finding holds, this behavior could potentially save some turtle species from extinction by balancing their sex ratios. A reptile’s sex depends on hormones produced during development. For crocodiles, many fish, some lizards, and most turtles, those hormones in turn depend on external temperatures. Cooler temperatures typically lead to more males, and warmer temperatures generally lead to more females. That means a shift of just 2°C can make all of the offspring one sex. As average global temperatures rise, such a strategy could doom some species, including the already-endangered Chinese pond turtle (Mauremys reevesii). As weather warms, warmer eggs produce more and more females—leaving them fewer males to mate with. Wondering whether turtle embryos could respond to rapidly changing temperatures, scientists from the Chinese Academy of Sciences in Beijing examined the behavior of the Chinese soft-shelled turtle (Pelodiscus sinensis). They discovered that the embryos could in fact move between cooler and warmer spots inside their paperclip-size eggs, they reported in 2011 in the Proceedings of the National Academy of Sciences. © 2019 American Association for the Advancement of Science.

Keyword: Sexual Behavior
Link ID: 26477 - Posted: 08.02.2019

By Knvul Sheikh It’s a myth that black widow female spiders always kill and consume their mates. But courtship remains perilous for males, cannibalism or no. The terrain, navigated in the dark, is challenging. The female’s web releases come-hither pheromones, but only about 12 percent of prospective males manage to reach it. And once there, they can expect to face male rivals competing to pass their genes on to the next generation. Usually, this results in wild displays of machismo. The males slash the female’s webs to make them less enticing to others. They deposit “mating plugs” in the female’s body to block rival sperm. Why not simply avoid the competition and seek out females’ webs empty of other males? But male black widows actually seem to thrive on the competition, according to a study published Wednesday in the Proceedings of the Royal Society B: Biological Sciences. Researchers found that male black widows find potential mates faster by following the silk trails left behind by other males. “Males have to race to find females,” said Catherine Scott, an arachnologist at the University of Toronto Scarborough in Canada and the study’s lead author. “It makes sense for them to try to use all the tricks they can to find females as soon as possible, even if there are other males that have already found her.” If a male arrives an hour or two late at a female’s web, he still has a chance to interrupt the courting rituals of other males, and could still be the first to mate with the female, Ms. Scott said. Males typically make their way to a rendezvous by following female pheromones back to their source. But those signals must be at just the right distance, and uninterrupted by shifting winds and other factors. © 2019 The New York Times Company

Keyword: Sexual Behavior; Evolution
Link ID: 26476 - Posted: 08.01.2019

By Brooke N. Dulka As you read this article, your brain has begun a series of complicated chemical steps in order to form a memory. How long you keep this memory may well depend on whether you are a man or a woman. Some scientists think that the reason for this difference may be estrogens. Women are disproportionately affected by Alzheimer’s disease, dementia and memory loss. In fact, almost two thirds of Americans living with Alzheimer’s are women. While researchers across the globe are still working to uncover the basic mechanisms of learning and memory, it is now known that estrogens help to regulate memory formation in both males and females. From a cultural and societal standpoint, when people think of estrogen they probably imagine pregnancy, periods and woman-fueled rage. Most people probably don’t consider memory; but maybe it’s time we all start thinking about estrogens’ role in memory a little more. Karyn Frick, a professor of psychology at the University of Wisconsin-Milwaukee, studies the connection between estrogens and memory. She and her students are among the scientists working to uncover the basic cellular and molecular mechanisms underlying memory formation. Part of Frick’s research focuses on how estrogens enhance memory, particularly through their action in the hippocampus. © 2019 Scientific American

Keyword: Hormones & Behavior; Learning & Memory
Link ID: 26470 - Posted: 07.31.2019

Carolyn Wilke Most frogs lay oodles of eggs and quickly hop away. But some poison dart frogs baby their offspring, cleaning and hydrating eggs laid on land and piggybacking hatched tadpoles to water. A peek inside the brains of these nurturing amphibians reveals that in males and females, two regions linked with caring for young are the same — a finding that may provide clues to the neural underpinnings of parental behavior, researchers report online July 17 in Proceedings of the Royal Society B. From humans to crocodiles, many creatures tend to their young. “But we actually understand very little about how the brain makes parental behaviors,” says Eva Fischer, a neuroethologist at Stanford University. To study how such care is wired into the amphibian brain, Fischer and her colleagues looked at neural activity in three poison dart frog species with different parenting strategies: Dendrobates tinctorius, among whom the males take care of the young; Oophaga sylvatica, whose females do the parenting; and Ranitomeya imitator, whose offspring are cared for by a monogamous male and female pair. The researchers collected and quickly killed 25 frogs while the amphibians were toting their tadpoles to water, in order to study the brain while it was still influenced by the parental task. Another 59 brains from non-caregiving frog species or caregivers’ partners were also included in the study. The researchers froze the frog brains and sliced them like loaves of bread. They stained the layers of tissue to pinpoint which nerve cells, or neurons, were turned on. In all three species, a brain region called the preoptic area was lit up with activity in caregiving frogs, but not in those of non-caregiving animals. |© Society for Science & the Public 2000 - 2019.

Keyword: Sexual Behavior; Evolution
Link ID: 26451 - Posted: 07.26.2019

Briar Stewart · A Canadian-born researcher is helping to launch the first substantial study of transgender athletes in a bid to better understand how transitioning and hormone therapy affects athletic performance. The issue of how to include transgender women in competition is centred around rules, rights and biological differences. And the debate about what constitutes an unfair advantage is heated, which is why medical physicist Joanna Harper hopes science can steer the conversation. "Until we have several of these larger-scale studies done worldwide, it's hard to be truly definitive on anything," she said. Harper, who is also an adviser to the International Olympic Committee (IOC), will be moving to the U.K. this fall to help lead the research into transgender athletes. The work will be carried out at Loughborough University, through its School of Sport, Exercise and Health Sciences. Personal motivation It was Harper's own experience that motivated her to try and track transgender athletes both before and after a gender transition. Harper, who is originally from Parry Sound, Ont, but is now based in Portland, Ore., has been a competitive runner for decades. When she was younger and racing as a male, her marathon time was a very quick two hours and 23 minutes. But once she started her transition in 2004 and began taking testosterone blockers and estrogen, her pace slowed. "Within nine months of hormone therapy, I was running 12 per cent slower," she said. "That's the difference between serious male distance runners and serious female distance runners." Harper, now in her 60s, still competes, racing alongside women. She wins some events and loses others, which is why she asserts that if trans women can become hormonally like other women, competition can be "equitable and meaningful." ©2019 CBC/Radio-Canada.

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 26444 - Posted: 07.24.2019

Scientists say they may have discovered why more women than men have Alzheimer's disease and dementia. It has always been thought that women living longer than men was the reason. But new research presented at an international conference suggests this may not be the whole story. Differences in brain connectivity and sex-specific genes linked to risk could explain the numbers, the researchers say. Most people living with Alzheimer's - the most common cause of dementia - are women. In the UK, about 500,000 women have dementia, compared with 350,000 men. Most people who develop the disease are over the age of 65 but it is not a normal part of ageing. Alzheimer's disease can affect younger people too. Researchers from Vanderbilt University Medical Centre studied brain scans of hundreds of men and women, looking at the pattern of a protein called tau. One of the characteristic features of Alzheimer's is the build-up of proteins called tau and amyloid in the brain. When they form toxic, tangled clumps, this causes brain cells to die, leading to memory problems. The researchers found differences between the sexes in how tau was spread across regions of the brain. Women appeared to have better connectivity between the regions where tau protein builds up - and this had implications for the brain, the study said. With this higher connectivity, women's brains may be at risk of faster spread of tau - and of cognitive decline. Dr Jana Voigt, head of research at Alzheimer's Research UK, said the study revealed "sex-specific differences in brain connectivity that could contribute to differing Alzheimer's risk in men and women". © 2019 BBC.

Keyword: Alzheimers; Sexual Behavior
Link ID: 26434 - Posted: 07.20.2019

Nicola Davis The belief that men are more likely to get turned on by sexual images than women may be something of a fantasy, according to a study suggesting brains respond to such images the same way regardless of biological sex. The idea that, when it comes to sex, men are more “visual creatures” than women has often been used to explain why men appear to be so much keener on pornography. But the study casts doubt on the notion. “We are challenging that idea with this paper,” said Hamid Noori, co-author of the research from the Max Planck Institute for Biological Cybernetics in Germany. “At least at the level of neural activity … the brains of men and women respond the same way to porn.” Writing in the Proceedings of the National Academy of Sciences, Noori and his colleagues report how they came to their conclusions by analysing the results of 61 published studies involving adults of different biological sex and sexual orientation. The subjects were shown everyday images of people as well as erotic images while they lay inside a brain-scanning machine. Noori said all participants rated the sexual images as arousing before being scanned. Previously studies based on self-reporting have suggested men are more aroused by images than women, and it has been proposed that these differences could be down to the way the brain processes the stimuli – but studies have returned different results. Now, looking at the whole body of research, Noori and his colleagues say they have found little sign of functional differences. For both biological sexes, a change in activity was seen in the same brain regions including the amygdala, insula and striatum when sexual images were shown. © 2019 Guardian News & Media Limited

Keyword: Sexual Behavior
Link ID: 26423 - Posted: 07.16.2019

By Nicholas Bakalar Hormone therapy for prostate cancer is associated with an increased risk for dementia, a new study has found. Androgen deprivation therapy, or A.D.T., is used to treat prostate cancer of varying degrees of severity. It can significantly reduce the risk for cancer progression and death. The study, in JAMA Network Open, included 154,089 men whose average age was 74 and who had diagnoses of prostate cancer. Of these, 62,330 received A.D.T. and the rest did not. In an average follow-up of eight years, the scientists found that compared with men who had no hormone therapy, one to four doses of A.D.T. was associated with a 19 percent increased risk for both Alzheimer’s disease and other forms of dementia, and the risk increased with the number of doses. At five to eight doses the increased risk was 28 percent for Alzheimer’s and 24 percent for other dementias. The lead author, Ravishankar Jayadevappa, an associate professor at the University of Pennsylvania Perelman School of Medicine, said that for advanced cancer, A.D.T. can be a lifesaving treatment and should not be avoided because of any increased risk for dementia. But, he said, “Patients with localized cancer should be looking at the risks of dementia, and possibly avoiding A.D.T.” © 2019 The New York Times Company

Keyword: Alzheimers; Hormones & Behavior
Link ID: 26384 - Posted: 07.04.2019

By Dana Najjar Four days after the birth of our daughter, my husband and I brought her home from the hospital. We were exhausted but giddy, ready to start our new lives. For nine months I had imagined what those first weeks at home would be like: sleepless nights, bleary-eyed arguments, a few late-night tears, all bundled up in the soft happy glow of new motherhood. In short, an adventure. But none of that materialized. What I came up against instead was a sheer wall of blinding panic. We had left the hospital with instructions to wake our newborn up every three hours to feed, but by the time we got home and settled in, five hours had elapsed, and nothing would rouse her long enough to nurse. She lay limp in my arms, drifting in and out of sleep, howling uncontrollably just long enough to tire herself out. We took our cues from the internet and tickled her feet with ice cubes, placed wet towels on her head and blew onto her face, but only managed to upset her more. And somewhere between trying to persuade her to latch for what felt like the hundredth time and willing my body to stay awake, it struck me that I had made a terrible mistake, one that I could never unmake. My stomach lurched, my hands and feet went numb and my heart began to pound. © 2019 Scientific American

Keyword: Depression; Hormones & Behavior
Link ID: 26359 - Posted: 06.26.2019