by Niko McCarty Mutations in TSC2, a gene linked to autism and a related condition called tuberous sclerosis complex, cause developing neurons to ignore chemical cues that help them connect with each other, a new study suggests. The results may explain the altered wiring patterns seen in the brains of people with such mutations. TSC2 mutations disrupt the formation of axons, the long neuronal projections that send electrical signals from one brain cell to another, past research shows. Researchers long attributed this faulty wiring to problems with mTOR, a signaling pathway that helps neurons synthesize proteins and other materials they need to grow and form connections; without TSC2, mTOR runs amok. In neurons derived from the skin of a person with tuberous sclerosis, however, the mTOR pathway is not hyperactive, the new study found. Instead, the work implicates a different signaling protein: RhoA. “We were very surprised,” says Timothy Gómez, professor of neuroscience at the University of Wisconsin-Madison, who led the new study. “We were expecting this to be all mTOR.” RhoA helps neurons reshape an internal cytoskeleton as they extend axons toward other cells. Deletions or duplications of genes in the Rho pathway are found in people with autism. Several genes in the autism-linked chromosomal region 16p11.2 also interact with RhoA. “I’m glad to see that many autism-related genes are now converging on RhoA, which actually makes a lot of sense,” says Lilia Iakoucheva, associate professor of psychiatry at the University of California, San Diego, who was not involved in the study. “The work is beautiful.” © 2021 Simons Foundation

Keyword: Autism; Development of the Brain
Link ID: 27880 - Posted: 06.29.2021

Kareem Clark With COVID-19 vaccines working and restrictions lifting across the country, it’s finally time for those now vaccinated who’ve been hunkered down at home to ditch the sweatpants and reemerge from their Netflix caves. But your brain may not be so eager to dive back into your former social life. Social distancing measures proved essential for slowing COVID-19’s spread worldwide – preventing upward of an estimated 500 million cases. But, while necessary, 15 months away from each other has taken a toll on people’s mental health. In a national survey last fall, 36% of adults in the U.S. – including 61% of young adults – reported feeling “serious loneliness” during the pandemic. Statistics like these suggest people would be itching to hit the social scene. But if the idea of making small talk at a crowded happy hour sounds terrifying to you, you’re not alone. Nearly half of Americans reported feeling uneasy about returning to in-person interaction regardless of vaccination status. Transparent, research-based, written by experts – and always free. So how can people be so lonely yet so nervous about refilling their social calendars? Well, the brain is remarkably adaptable. And while we can’t know exactly what our brains have gone through over the last year, neuroscientists like me have some insight into how social isolation and resocialization affect the brain.

Keyword: Stress
Link ID: 27879 - Posted: 06.29.2021

By Bruce Bower A fossil skull nicknamed “Dragon Man” has surfaced in China under mysterious circumstances, with big news for Neandertals. Dragon Man belonged to a previously unrecognized Stone Age species that replaces Neandertals as the closest known relatives of people today, researchers say. A nearly complete male skull now housed in the Geoscience Museum of Hebei GEO University in Shijiazhuang, China, represents a species dubbed Homo longi by Hebei GEO paleoanthropologist Xijun Ni and his colleagues. The scientists describe the skull, which dates to at least 146,000 years ago, and analyze its position in Homo evolution in three papers published June 25 in The Innovation. Qiang Ji, a paleontologist also at Hebei GEO, received the skull in 2018 from a farmer who said the fossil had been dug up by a coworker of his grandfather’s in 1933. During bridge construction over a river in Harbin, China, the worker allegedly scooped the skull out of river sediment. Whether or not that story is true, this fossil could help answer questions about a poorly understood period of human evolution. “The Harbin cranium presents a combination of features setting it apart from other Homo species,” Ji says. The name H. longi derives from a Chinese term for the province where it was found, which translates as “dragon river.” That term inspired the nickname Dragon Man. As in H. sapiens, the Harbin skull held a large brain situated atop a relatively short face and small cheek bones. But traits such as a long, low braincase, thick brow ridges, large molars and almost square eye sockets recall several extinct Homo populations or species, including Neandertals and H. heidelbergensis (SN: 4/1/20). © Society for Science & the Public 2000–2021

Keyword: Evolution
Link ID: 27878 - Posted: 06.26.2021

Allison Aubrey Imagine a sound that travels with you no matter where you go. Whether it's a ring, a whoosh or a crickets-like buzz, you can't escape it. "Mine was like this high-pitched sonic sound," says Elizabeth Fraser, who developed tinnitus last fall. It came on suddenly at a time when many people delayed doctor visits due to the coronavirus pandemic. "It just felt like an invasion in my head, so I was really distressed," Fraser recalls. Tinnitus is the perception of ringing when, in fact, no external sound is being produced. "You can equate it to a phantom sound," explains Sarah Sydlowski, a doctor of audiology at Cleveland Clinic. The Centers for Disease Control and Prevention estimates that 20 million Americans have chronic tinnitus. And studies show the pandemic ushered in both new cases and a worsening of the condition among people who already had it. The British Tinnitus Association reported a surge in the number of people accessing its services, including a 256% increase in the number of web chats amid the pandemic. Elizabeth Fraser started hearing a "high-pitched sonic sound" in her ears last fall. It came on suddenly at a time when many people delayed doctor visits due to the coronavirus pandemic. "It just felt like an invasion in my head, so I was really distressed," Fraser recalls. © 2021 npr

Keyword: Hearing
Link ID: 27877 - Posted: 06.26.2021

Kurt Schwenk As dinosaurs lumbered through the humid cycad forests of ancient South America 180 million years ago, primeval lizards scurried, unnoticed, beneath their feet. Perhaps to avoid being trampled by their giant kin, some of these early lizards sought refuge underground. Here they evolved long, slender bodies and reduced limbs to negotiate the narrow nooks and crevices beneath the surface. Without light, their vision faded, but to take its place, an especially acute sense of smell evolved. It was during this period that these proto-snakes evolved one of their most iconic traits – a long, flicking, forked tongue. These reptiles eventually returned to the surface, but it wasn’t until the extinction of dinosaurs many millions of years later that they diversified into myriad types of modern snakes. As an evolutionary biologist, I am fascinated by these bizarre tongues – and the role they have played in snakes’ success. Snake tongues are so peculiar they have fascinated naturalists for centuries. Aristotle believed the forked tips provided snakes a “twofold pleasure” from taste – a view mirrored centuries later by French naturalist Bernard Germain de Lacépède, who suggested the twin tips could adhere more closely to “the tasty body” of the soon-to-be snack. A 17th-century astronomer and naturalist, Giovanni Battista Hodierna, thought snakes used their tongues for “picking the dirt out of their noses … since they are always grovelling on the ground.” Others contended the tongue captured flies “with wonderful nimbleness … betwixt the forks,” or gathered air for sustenance.

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 27876 - Posted: 06.26.2021

By Kim Tingley Childhood obesity has increased significantly in the United States during the past four decades. In 1980, about 5 percent of the country’s children between 2 and 19 were experiencing obesity, according to the C.D.C.; as of 2018, more than 19 percent were — and an additional 16 percent were considered overweight. Because children are far more likely to gain an unhealthful amount of weight while out of school over the summer, experts were worried last spring when in-person schooling was suspended indefinitely because of the pandemic. They feared extended closures might “exacerbate the epidemic of childhood obesity and increase disparities in obesity risk,” as researchers from the Mailman School of Public Health at Columbia University and colleagues put it in a paper in the journal Obesity in June 2020. That, in turn, would mean more children living with related conditions such as Type 2 diabetes, hypertension and fatty-liver disease. Those concerns were warranted, according to a May study in Pediatrics. Based on measurements of body mass index taken for more than 500,000 children between the ages of 2 and 17 during visits to the Children’s Hospital of Philadelphia Care Network, researchers found that, on average, between January 2019 and December 2020 the prevalence of obesity increased by almost 2 percentage points overall, from 13.7 percent to 15.4 percent. (In the most recent years for which national data is available, the increase has been 1 percentage point or less.) Black and Latino children, as well as those from families with lower incomes, displayed sharper increases than children from other groups did. Such gains early in life make it more likely that children will have higher B.M.I.s when they grow up. (Obesity already affects more than 40 percent of American adults.) “This isn’t just baby fat that’s going to go away,” says Brian Jenssen, the study’s lead author and a pediatrician at Children’s. “That’s why I think this is so alarming.” © 2021 The New York Times Company

Keyword: Obesity
Link ID: 27875 - Posted: 06.26.2021

by Rachel Zamzow Most mornings, Huda Zoghbi, 67, climbs a glass-encased, curling staircase to reach her lab on the top and 13th floor of the Jan and Dan Duncan Neurological Research Institute in Houston, Texas. The twisting glass tower, which she designed with a team of architects, echoes the double helix of DNA — a structure that has been central to her career-long quest to uncover genes underlying neurological conditions. As the institute’s director — and as a scientist— she is known for going beyond the standard job description. Genetics researchers often cast a wide net and sequence thousands of genes at a time. But in her prolific career, Zoghbi has focused on a handful of genes, methodically building up an understanding of their function one careful step at a time. Thanks to that approach, Zoghbi has made a number of landmark discoveries, including identifying the genetic roots of Rett syndrome, an autism-related condition that primarily affects girls, as well as the genetic mutations that spur spinocerebellar ataxia, a degenerative motor condition. She has authored more than 350 journal articles. Her accomplishments have earned her almost every major biology and neuroscience research award, including the prestigious Breakthrough Prize in 2017 and the Brain Prize in 2020. “She’s clearly the international leader in the field,” said the late Stephen Warren, professor of human genetics at Emory University in Atlanta, Georgia. Zoghbi never set out to lead a large research center, she says — her heart is in the lab. That said, she has excelled at it: Since the institute’s inception in 2010, it has grown to host more than 200 scientists and fostered more than 70 new disease gene discoveries. © 2021 Simons Foundation

Keyword: Movement Disorders; Development of the Brain
Link ID: 27874 - Posted: 06.26.2021

As I lean back in the leather recliner, my limbs feel heavy. The strong dose of ketamine I've just taken is making it harder to move, so I struggle to put on my headphones and eyeshades. Soothing music lulls me into deep relaxation, as my consciousness starts to float away from my body and into a world of swirling lights, colours and images. I'm not at a new-age music festival, or in a seedy underground drug den. This fully-legal experience is taking place under medical supervision at Field Trip Health in Toronto, a clinic that offers psychedelic-assisted therapy for those suffering treatment-resistant mental illnesses like depression and PTSD. The clinic, which was the first of its kind in Canada, opened last year. Since then, similar clinics have opened in Quebec, Alberta, Saskatchewan, B.C., and Nova Scotia. Ketamine was first approved for use in Canada and the U.S. as a general anesthetic more than 50 years ago. Since then it has gained a reputation as a party drug, with names like Special K or Vitamin K. Today, it's increasingly being used as a fast-acting and effective treatment for depression. But it isn't without controversy. I've dealt with bouts of depression and suicidal thoughts for about as long as I can remember. By the fall of 2020, after months of isolation due to the COVID-19 pandemic had taken their toll, my depression was as bad as it had ever been. ©2021 CBC/Radio-Canada.

Keyword: Depression; Drug Abuse
Link ID: 27873 - Posted: 06.26.2021

By Juan Siliezar Harvard Staff Writer When Erin Hecht was earning her Ph.D. in neuroscience more than a decade ago, she watched a nature special on the Russian farm-fox experiment, one of the best-known studies on animal domestication. The focus of that ongoing research, which began in 1958, is to try to understand the process by which wild wolves became domesticated dogs. Scientists have been selectively breeding two strains of silver fox — an animal closely related to dogs — to exhibit certain behaviors. One is bred to be tame and display dog-like behaviors with people, such as licking and tail-wagging, and the other to react with defensive aggression when faced with human contact. A third strain acts as the control and isn’t bred for any specific behaviors. Hecht, who’s now an assistant professor in the Harvard Department of Human Evolutionary Biology, was fascinated by the experiment, which has helped scientists closely analyze the effects of domestication on genetics and behavior. But she also thought something fundamental was missing. What she didn’t know was that filling that knowledge gap could potentially force reconsideration of what was known about the connection between evolutionary changes in behavior and those in the brain. “In that TV show, there was nothing about the brain,” Hecht said. “I thought it was kind of crazy that there’s this perfect opportunity to be studying how changes in brain anatomy are related to changes in the genome and changes in behavior, but nobody was really doing it yet.”

Keyword: Aggression; Evolution
Link ID: 27872 - Posted: 06.23.2021

By Nancy Clanton, Studies have shown COVID-19 can cause brain complications in some patients’ brains, from memory problems to strokes. A new study has found the brains of people who died from COVID-19 were remarkably similar to the brains of people who die from Alzheimer’s and Parkinson’s, showing inflammation and disrupted circuitry, researchers reported. “The brains of patients who died from severe COVID-19 showed profound molecular markers of inflammation, even though those patients didn’t have any reported clinical signs of neurological impairment,” study co-senior author Tony Wyss-Coray, a professor of neurology and neurological sciences at Stanford University, said in a press release. According to Wyss-Coray, about a third of hospitalized COVID-19 patients report neurological symptoms, such as fuzzy thinking, forgetfulness, difficulty concentrating and depression, and these problems continue for long haul patients even when they’ve recovered from COVID. For their study, his team analyzed brain tissue from eight people who died of COVID-19 and 14 who died of other causes. The researchers found significant inflammation in the brains of the deceased COVID-19 patients. However, their brain tissue showed no signs of SARS-CoV-2, the virus that causes COVID-19. Wyss-Coray added that scientists disagree about whether the virus is present in COVID-19 patients’ brains. © 2021 The Atlanta Journal-Constitution.

Keyword: Parkinsons; Alzheimers
Link ID: 27871 - Posted: 06.23.2021

by Charles Q. Choi Mutations in CUL3, a leading autism gene, may disrupt the movements of neurons during development and interrupt the precise assembly of the brain, a new study suggests. Correcting this misdirection could lead to a therapy for autism in people with CUL3 mutations, the researchers say. Mutations that knock CUL3 out of commission are linked not only with autism, but also with varying levels of intellectual disability, movement problems, attention deficit hyperactivity disorder, epilepsy and sleep disturbances. Scientists have thoroughly explored how the protein that CUL3 encodes helps tag and break down other, expendable proteins in cells, but much remains unknown about its role in the developing brain. For the new work, researchers made mice that have only one functioning CUL3 gene instead of the usual two. These mice have movement problems, diminished sociability and poor memory — traits reminiscent of those in people with CUL3 mutations. The team also engineered mice in which they could knock out one copy of CUL3 by giving the rodents the cancer drug tamoxifen. Turning off CUL3 in 30-day-old juvenile mice had little effect, which suggests that CUL3 mutations contribute to autism-like behaviors during brain development, the researchers say. Identifying this window “is critical to consider for future critical trials,” says lead investigator Gaia Novarino, professor of neuroscience at the Institute of Science and Technology in Klosterneuburg, Austria. © 2021 Simons Foundation

Keyword: Autism; Development of the Brain
Link ID: 27870 - Posted: 06.23.2021

Jordana Cepelewicz Smell, rather than sight, reigns as the supreme sense for most animals. It allows them to find food, avoid danger and attract mates; it dominates their perceptions and guides their behavior; it dictates how they interpret and respond to the deluge of sensory information all around them. “How we as biological creatures interface with chemistry in the world is profoundly important for understanding who we are and how we navigate the universe,” said Bob Datta, a neurobiologist at Harvard Medical School. Yet olfaction might also be the least well understood of our senses, in part because of the complexity of the inputs it must reckon with. What we might label as a single odor — the smell of coffee in the morning, of wet grass after a summer storm, of shampoo or perfume — is often a mixture of hundreds of types of chemicals. For an animal to detect and discriminate between the many scents that are key to its survival, the limited repertoire of receptors on its olfactory sensory neurons must somehow recognize a vast number of compounds. So an individual receptor has to be able to respond to many diverse, seemingly unrelated odor molecules. That versatility is at odds with the traditional lock-and-key model governing how selective chemical interactions tend to work. “In high school biology, that’s what I learned about ligand-receptor interactions,” said Annika Barber, a molecular biologist at Rutgers University. “Something has to fit precisely in a site, and then it changes the [protein’s atomic arrangement], and then it works.” All Rights Reserved © 2021

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27869 - Posted: 06.23.2021

By Nicholas Bakalar If you are a morning person, you may be at reduced risk for major depression, a new study suggests. Several studies of the body’s circadian sleep-wake cycle have shown that being an early bird is associated with a lower risk for depression. But those studies were observational so could not prove cause and effect. For example, people who are early birds may have other health or lifestyle behaviors that reduce their risk for depression — they may have a healthier diet, for example, exercise more, or have fewer health conditions, such as chronic pain, that are associated with depression. All these factors, and many others, could explain the decreased risk for depression, and not the fact of being an early bird. Moreover, depression itself causes sleep disturbances, so it could be that depression is a cause of being a night owl, rather than the other way around. The new study, however, offers more compelling evidence that going to bed early and waking early may, in itself, provide protection against depression, independent of other factors. The study, published in JAMA Psychiatry, uses a research method called Mendelian randomization that helps pinpoint the cause of what may be a cause-and-effect relationship. With Mendelian randomization, researchers can compare large groups of people based on genetic variants that are independent of other health or behavioral characteristics — in this case, the tendency to being a night owl or a morning person, inherited traits that are randomly allocated during our development in the womb. More than 340 genetic variants associated with circadian sleep rhythm have been identified, and the researchers can compare large groups of people with the genetic variants for being a morning person with groups that lack them. Nature has, in essence, set up the randomized experiment for them. © 2021 The New York Times Company

Keyword: Biological Rhythms; Depression
Link ID: 27868 - Posted: 06.23.2021

By Katie Free, Joel Goldberg When it comes to our senses, we frequently focus on the external—the crack of thunder, the glare of sunlight, the fragrance of flowers—that captured our attention in the first place. But our bodies also have a whole host of internal senses that tell our brains whether our hearts are beating at the right speed, for example, or whether our blood pressure is too high. These signals travel constantly via hormones and nerves, including a mysterious 100,000-fiber network called the vagus nerve. Now, new techniques are helping scientists map the thin, twisting branches of the vagus nerve—which connects the brain to the heart, intestines, and other internal organs—and make surprising discoveries about its role in memory and emotion. These findings have spawned investigations into treatments for everything from Alzheimer’s disease to post-traumatic stress disorder and have led to the approval of medical implants to help treat epilepsy and depression. When it comes to understanding the brain-mind connection, a gut check might not hurt. © 2021 American Association for the Advancement of Science.

Keyword: Epilepsy; Depression
Link ID: 27867 - Posted: 06.23.2021

An analysis of survey data from more than 280,000 young adults ages 18-35 showed that cannabis (marijuana) use was associated with increased risks of thoughts of suicide (suicidal ideation), suicide plan, and suicide attempt. These associations remained regardless of whether someone was also experiencing depression, and the risks were greater for women than for men. The study published online today in JAMA Network Open and was conducted by researchers at the National Institute on Drug Abuse (NIDA), part of the National Institutes of Health. “While we cannot establish that cannabis use caused the increased suicidality we observed in this study, these associations warrant further research, especially given the great burden of suicide on young adults,” said NIDA Director Nora Volkow, M.D., senior author of this study. “As we better understand the relationship between cannabis use, depression, and suicidality, clinicians will be able to provide better guidance and care to patients.” The number of adults in the United States who use cannabis more than doubled from 22.6 million in 2008 to 45.0 million in 2019, and the number of daily or near-daily users almost tripled from 3.6 million to 9.8 million in 2019. Over the same time span, the number of adults with depression also increased, as did the number of people who reported suicidal ideation or plan or who died by suicide. To date, however, the relationship between trends in cannabis use and suicidality is not well understood. The current study sought to fill this gap.

Keyword: Depression; Drug Abuse
Link ID: 27866 - Posted: 06.23.2021

By Christof Koch Consider the following experiences: • You're headed toward a storm that's a couple of miles away, and you've got to get across a hill. You ask yourself: “How am I going to get over that, through that?” • You see little white dots on a black background, as if looking up at the stars at night. Advertisement • You look down at yourself lying in bed from above but see only your legs and lower trunk. These may seem like idiosyncratic events drawn from the vast universe of perceptions, sensations, memories, thoughts and dreams that make up our daily stream of consciousness. In fact, each one was evoked by directly stimulating the brain with an electrode. As American poet Walt Whitman intuited in his poem “I Sing the Body Electric,” these anecdotes illustrate the intimate relationship between the body and its animating soul. The brain and the conscious mind are as inexorably linked as the two sides of a coin. Recent clinical studies have uncovered some of the laws and regularities of conscious activity, findings that have occasionally proved to be paradoxical. They show that brain areas involved in conscious perception have little to do with thinking, planning and other higher cognitive functions. Neuroengineers are now working to turn these insights into technologies to replace lost cognitive function and, in the more distant future, to enhance sensory, cognitive or memory capacities. For example, a recent brain-machine interface provides completely blind people with limited abilities to perceive light. These tools, however, also reveal the difficulties of fully restoring sight or hearing. They underline even more the snags that stand in the way of sci-fi-like enhancements that would enable access to the brain as if it were a computer storage drive. © 2021 Scientific American,

Keyword: Consciousness
Link ID: 27865 - Posted: 06.19.2021

By Christa Lesté-Lasserre In the animal kingdom, killer whales are social stars: They travel in extended, varied family groups, care for grandchildren after menopause, and even imitate human speech. Now, marine biologists are adding one more behavior to the list: forming fast friendships. A new study suggests the whales rival chimpanzees, macaques, and even humans when it comes to the kinds of “social touching” that indicates strong bonds. The study marks “a very important contribution to the field” of social behavior in dolphins and whales, says José Zamorano-Abramson, a comparative psychologist at the Complutense University of Madrid who wasn’t involved in the work. “These new images show lots of touching of many different types, probably related to different kinds of emotions, much like the complex social dynamics we see in great apes.” Audio and video recordings have shown how some marine mammals maintain social structures—including male dolphins that learn the “names” of close allies. But there is little footage of wild killer whales—which hunt and play in open water. Although the whales only swim at about 6 kilometers per hour, it’s hard to fully observe them from boats, and they might not act naturally near humans, Zamorano-Abramson says. That’s where drone technology came swooping in. Michael Weiss, a behavioral ecologist at the Center for Whale Research in Friday Harbor, Washington, teamed up with colleagues to launch unmanned drones from their 6.5-meter motorboat and from the shores of the northern Pacific Ocean, flying them 30 to 120 meters above a pod of 22 southern resident killer whales. That was high enough to respect federal aviation requirements—and not bother the whales. They logged 10 hours of footage over a 10-day period, marking the first time drones have been used to study friendly physical contacts in any cetacean. © 2021 American Association for the Advancement of Science.

Keyword: Evolution; Stress
Link ID: 27864 - Posted: 06.19.2021

By Diana Kwon Long before the earliest animals swam through the water-covered surface of Earth’s ancient past, one of the most important encounters in the history of life took place. A primitive bacterium was engulfed by our oldest ancestor — a solo, free-floating cell. The two fused to form a mutually beneficial relationship that has lasted more than a billion years, with the latter providing a safe, comfortable home and the former becoming a powerhouse, fueling the processes necessary to maintain life. That’s the best hypothesis to date for how the cellular components, or organelles, known as mitochondria came to be. Today, trillions of these bacterial descendants live within our bodies, churning out ATP, the molecular energy source that sustains our cells. Despite being inextricably integrated into the machinery of the human body, mitochondria also carry remnants of their bacterial past, such as their own set of DNA. The DNA that constitutes the human genome is contained within the nucleus of our cells. But mitochondria possess their own set of circular DNA, which is likely a remnant of their ancient bacterial past. These features make mitochondria both a critical element of our cells and a potential source of problems. Like the DNA inside the nuclei of our cells that makes up the human genome, mitochondrial DNA can harbor mutations. Age, stress and other factors may disrupt mitochondria’s many functions. On top of that, mitochondrial injury can release molecules that, due to their similarities to those made by bacteria, can be mistaken by our immune system as foreign invaders, triggering a harmful inflammatory response against our own cells. © 2021 Annual Reviews, Inc

Keyword: Schizophrenia; Alzheimers
Link ID: 27863 - Posted: 06.19.2021

Christopher M. Filley One of the most enduring themes in human neuroscience is the association of higher brain functions with gray matter. In particular, the cerebral cortex—the gray matter of the brain's surface—has been the primary focus of decades of work aiming to understand the neurobiological basis of cognition and emotion. Yet, the cerebral cortex is only a few millimeters thick, so the relative neglect of the rest of the brain below the cortex has prompted the term “corticocentric myopia” (1). Other regions relevant to behavior include the deep gray matter of the basal ganglia and thalamus, the brainstem and cerebellum, and the white matter that interconnects all of these structures. On page 1304 of this issue, Zhao et al. (2) present compelling evidence for the importance of white matter by demonstrating genetic influences on structural connectivity that invoke a host of provocative clinical implications. Insight into the importance of white matter in human behavior begins with its anatomy (3–5) (see the figure). White matter occupies about half of the adult human brain, and some 135,000 km of myelinated axons course through a wide array of tracts to link gray matter regions into distributed neural networks that serve cognitive and emotional functions (3). The human brain is particularly well interconnected because white matter has expanded more in evolution than gray matter, which has endowed the brain of Homo sapiens with extensive structural connectivity (6). The myelin sheath, white matter's characteristic feature, appeared late in vertebrate evolution and greatly increased axonal conduction velocity. This development enhanced the efficiency of distributed neural networks, expanding the transfer of information throughout the brain (5). Information transfer serves to complement the information processing of gray matter, where neuronal cell bodies, synapses, and a variety of neurotransmitters are located (5). The result is a brain with prodigious numbers of both neurons and myelinated axons, which have evolved to subserve the domains of attention, memory, emotion, language, perception, visuospatial processing, executive function (5), and social cognition (7). © 2021 American Association for the Advancement of Science.

Keyword: Development of the Brain; Attention
Link ID: 27862 - Posted: 06.19.2021

By Laura Sanders Some big scientific discoveries aren’t actually discovered. They are borrowed. That’s what happened when scientists enlisted proteins from an unlikely lender: green algae. Cells of the algal species Chlamydomonas reinhardtii are decorated with proteins that can sense light. That ability, first noticed in 2002, quickly caught the attention of brain scientists. A light-sensing protein promised the power to control neurons — the brain’s nerve cells — by providing a way to turn them on and off, in exactly the right place and time. Nerve cells genetically engineered to produce the algal proteins become light-controlled puppets. A flash of light could induce a quiet neuron to fire off signals or force an active neuron to fall silent. “This molecule is the light sensor that we needed,” says vision neuroscientist Zhuo-Hua Pan, who had been searching for a way to control vision cells in mice’s retinas. The method enabled by these loaner proteins is now called optogenetics, for its combination of light (opto) and genes. In less than two decades, optogenetics has led to big insights into how memories are stored, what creates perceptions and what goes wrong in the brain during depression and addiction. Using light to drive the activity of certain nerve cells, scientists have toyed with mouse hallucinations: Mice have seen lines that aren’t there and have remembered a room they had never been inside. Scientists have used optogenetics to make mice fight, mate and eat, and even given blind mice sight. In a big first, optogenetics recently restored aspects of a blind man’s vision. © Society for Science & the Public 2000–2021.

Keyword: Brain imaging; Learning & Memory
Link ID: 27861 - Posted: 06.19.2021