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Zebrafish give new insight to sound sensitivity in autism
These tiny fish are helping scientists understand how the human brain processes sound.
- Fragile X syndrome is a genetic disorder caused by changes in a gene that scientists call the "fragile X mental retardation 1 (FMR1)" gene. People who have FXS or autism often struggle with sensitivity to sound.
- According to the research team, FXS is caused by the disruption of a gene. By disrupting that same gene in zebrafish larvae, they can examine the effects and begin to understand more about this disrupted gene in the human brain.
- Using the zebrafish, Dr. Constantin and the team were able to gather insights into which parts of the brain are used to process sensory information.
Associate professor Ethan Scott and Dr. Lena Constantin recently carried out a study using zebrafish that carry the same genetic mutations as humans with "Fragile X" syndrome and autism. During their research, they discovered the neural networks and pathways that produce hypersensitivities to sound in both zebrafish and humans.
What is Fragile X syndrome?
Fragile X syndrome (commonly referred to as FXS) is a genetic disorder caused by changes in a gene that scientists call the "fragile X mental retardation 1 (FMR1)" gene. This gene typically makes a protein called fragile X mental retardation protein (FMRP) that's needed for typical brain development. The brains of people with FXS do not make this protein, and if it is there, it's abnormal.
What is autism?
Autism spectrum disorder (ASD) is a developmental disability that can cause significant social, communication, and behavioral challenges. People with ASD may communicate, interact, behave, and learn in different ways than most other people. A current diagnosis of ASD now includes several conditions that were previously diagnosed separately such as autistic disorder, pervasive developmental disorder, and Asperger syndrome.
By disrupting a specific gene in Zebrafish, we're able to better understand the same disruption of that gene in humans with FXS or autism.
Credit: slowmotiongli on Adobe Stock
"Loud noises often cause sensory overload and anxiety in people with autism and Fragile X syndrome -- sensitivity to sound is common to both conditions," Dr. Constantin explained to Science Daily.
How do zebrafish relate to humans with autism?
According to the research team, FXS is caused by the disruption of a gene. By disrupting that same gene in zebrafish larvae, they can examine the effects and begin to understand more about this disrupted gene in the human brain.
The thalamus, according to Dr. Constantin, works as a control center, relaying sensory information from around the body to different parts of the brain. The hindbrain then coordinates different behavioral responses. Using the different sound tests, the team was able to study the whole brain of the zebrafish larvae under microscopes and see the activity of each brain cell individually.
According to Dr. Constantin, the research team recorded the brain activity of zebrafish larvae while showing them movies or exposing them to bursts of sound. The movies stimulated movement, a reaction to the visual stimuli that was the same for fish with the Fragile X mutation and those without. However, when the fish were given a burst of white noise, there was a dramatic difference in the brain activity of the fish with the Fragile X mutation.
After seeing how the noise radically affected the fish brain, the team designed a range of 12 different volumes of sound and found the Fragile X model fish could hear much quieter volumes than the control fish.
"The fish with Fragile X mutations had more connections between different regions of their brain and their responses to the sounds were more plentiful in the hindbrain and thalamus," said Dr. Constantin.
Essentially, the fish with Fragile X mutation had more connections between the regions of their brain and so their responses to the sounds were more notable.
Understanding how this gene disruption works in zebrafish will give us a better understanding of sound hypersensitivity in humans with FXS or autism.
"How our neural pathways develop and respond to the stimulation of our senses gives us insights into which parts of the brain are used and how sensory information is processed," Dr. Constantin said.
Using the zebrafish, Dr. Constantin and the team were able to gather insights into which parts of the brain are used to process sensory information.
"We hope that by discovering fundamental information about how the brain processes sound, we will gain further insights into the sensory challenges faced by people with Fragile X syndrome and autism."
- How Do We Perceive Sound? - Big Think ›
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- Why intelligent people suffer more mental disorders - Big Think ›
- Autism sensory struggles: the peripheral nerve system - Big Think ›
How would the ability to genetically customize children change society? Sci-fi author Eugene Clark explores the future on our horizon in Volume I of the "Genetic Pressure" series.
- A new sci-fi book series called "Genetic Pressure" explores the scientific and moral implications of a world with a burgeoning designer baby industry.
- It's currently illegal to implant genetically edited human embryos in most nations, but designer babies may someday become widespread.
- While gene-editing technology could help humans eliminate genetic diseases, some in the scientific community fear it may also usher in a new era of eugenics.
Tribalism and discrimination<p>One question the "Genetic Pressure" series explores: What would tribalism and discrimination look like in a world with designer babies? As designer babies grow up, they could be noticeably different from other people, potentially being smarter, more attractive and healthier. This could breed resentment between the groups—as it does in the series.</p><p>"[Designer babies] slowly find that 'everyone else,' and even their own parents, becomes less and less tolerable," author Eugene Clark told Big Think. "Meanwhile, everyone else slowly feels threatened by the designer babies."</p><p>For example, one character in the series who was born a designer baby faces discrimination and harassment from "normal people"—they call her "soulless" and say she was "made in a factory," a "consumer product." </p><p>Would such divisions emerge in the real world? The answer may depend on who's able to afford designer baby services. If it's only the ultra-wealthy, then it's easy to imagine how being a designer baby could be seen by society as a kind of hyper-privilege, which designer babies would have to reckon with. </p><p>Even if people from all socioeconomic backgrounds can someday afford designer babies, people born designer babies may struggle with tough existential questions: Can they ever take full credit for things they achieve, or were they born with an unfair advantage? To what extent should they spend their lives helping the less fortunate? </p>
Sexuality dilemmas<p>Sexuality presents another set of thorny questions. If a designer baby industry someday allows people to optimize humans for attractiveness, designer babies could grow up to find themselves surrounded by ultra-attractive people. That may not sound like a big problem.</p><p>But consider that, if designer babies someday become the standard way to have children, there'd necessarily be a years-long gap in which only some people are having designer babies. Meanwhile, the rest of society would be having children the old-fashioned way. So, in terms of attractiveness, society could see increasingly apparent disparities in physical appearances between the two groups. "Normal people" could begin to seem increasingly ugly.</p><p>But ultra-attractive people who were born designer babies could face problems, too. One could be the loss of body image. </p><p>When designer babies grow up in the "Genetic Pressure" series, men look like all the other men, and women look like all the other women. This homogeneity of physical appearance occurs because parents of designer babies start following trends, all choosing similar traits for their children: tall, athletic build, olive skin, etc. </p><p>Sure, facial traits remain relatively unique, but everyone's more or less equally attractive. And this causes strange changes to sexual preferences.</p><p>"In a society of sexual equals, they start looking for other differentiators," he said, noting that violet-colored eyes become a rare trait that genetically engineered humans find especially attractive in the series.</p><p>But what about sexual relationships between genetically engineered humans and "normal" people? In the "Genetic Pressure" series, many "normal" people want to have kids with (or at least have sex with) genetically engineered humans. But a minority of engineered humans oppose breeding with "normal" people, and this leads to an ideology that considers engineered humans to be racially supreme. </p>
Regulating designer babies<p>On a policy level, there are many open questions about how governments might legislate a world with designer babies. But it's not totally new territory, considering the West's dark history of eugenics experiments.</p><p>In the 20th century, the U.S. conducted multiple eugenics programs, including immigration restrictions based on genetic inferiority and forced sterilizations. In 1927, for example, the Supreme Court ruled that forcibly sterilizing the mentally handicapped didn't violate the Constitution. Supreme Court Justice Oliver Wendall Holmes wrote, "… three generations of imbeciles are enough." </p><p>After the Holocaust, eugenics programs became increasingly taboo and regulated in the U.S. (though some states continued forced sterilizations <a href="https://www.uvm.edu/~lkaelber/eugenics/" target="_blank">into the 1970s</a>). In recent years, some policymakers and scientists have expressed concerns about how gene-editing technologies could reanimate the eugenics nightmares of the 20th century. </p><p>Currently, the U.S. doesn't explicitly ban human germline genetic editing on the federal level, but a combination of laws effectively render it <a href="https://academic.oup.com/jlb/advance-article/doi/10.1093/jlb/lsaa006/5841599#204481018" target="_blank" rel="noopener noreferrer">illegal to implant a genetically modified embryo</a>. Part of the reason is that scientists still aren't sure of the unintended consequences of new gene-editing technologies. </p><p>But there are also concerns that these technologies could usher in a new era of eugenics. After all, the function of a designer baby industry, like the one in the "Genetic Pressure" series, wouldn't necessarily be limited to eliminating genetic diseases; it could also work to increase the occurrence of "desirable" traits. </p><p>If the industry did that, it'd effectively signal that the <em>opposites of those traits are undesirable. </em>As the International Bioethics Committee <a href="https://academic.oup.com/jlb/advance-article/doi/10.1093/jlb/lsaa006/5841599#204481018" target="_blank" rel="noopener noreferrer">wrote</a>, this would "jeopardize the inherent and therefore equal dignity of all human beings and renew eugenics, disguised as the fulfillment of the wish for a better, improved life."</p><p><em>"Genetic Pressure Volume I: Baby Steps"</em><em> by Eugene Clark is <a href="http://bigth.ink/38VhJn3" target="_blank">available now.</a></em></p>
Meteorologists propose a stunning new explanation for the mysterious events in the Bermuda Triangle.
One of life's great mysteries, the Bermuda Triangle might have finally found an explanation. This strange region, that lies in the North Atlantic Ocean between Bermuda, Miami and San Juan, Puerto Rico, has been the presumed cause of dozens and dozens of mind-boggling disappearances of ships and planes.
A unique exoplanet without clouds or haze was found by astrophysicists from Harvard and Smithsonian.
- Astronomers from Harvard and Smithsonian find a very rare "hot Jupiter" exoplanet without clouds or haze.
- Such planets were formed differently from others and offer unique research opportunities.
- Only one other such exoplanet was found previously.
Munazza Alam – a graduate student at the Center for Astrophysics | Harvard & Smithsonian.
Credit: Jackie Faherty
Jupiter's Colorful Cloud Bands Studied by Spacecraft<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="8a72dfe5b407b584cf867852c36211dc"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/GzUzCesfVuw?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Scientists discover burrows of giant predator worms that lived on the seafloor 20 million years ago.
- Scientists in Taiwan find the lair of giant predator worms that inhabited the seafloor 20 million years ago.
- The worm is possibly related to the modern bobbit worm (Eunice aphroditois).
- The creatures can reach several meters in length and famously ambush their pray.
A three-dimensional model of the feeding behavior of Bobbit worms and the proposed formation of Pennichnus formosae.
Credit: Scientific Reports
Beware the Bobbit Worm!<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="1f9918e77851242c91382369581d3aac"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/_As1pHhyDHY?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
The idea behind the law was simple: make it more difficult for online sex traffickers to find victims.