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Treatable brain inflammation may be behind tinnitus
Scientists may have seen a way to cure a maddening symptom of hearing loss.
- A treatment for tinnitus – a constant ringing in the ears – has been frustratingly elusive.
- Out-of-control inflammation, the brain's response to damage, may be the cause of long-term ringing in the ears.
- A study that examined mice with noise-induced hearing loss seems to have found the neural trigger for tinnitus.
Common, or subjective, tinnitus is no fun. If you have it, you know what we mean. And a lot of people do — some 500 million worldwide. It's a byproduct of hearing loss that produces a constant veil of high-frequency pitches that never abates. For sufferers, there is no silence, ever. Unfortunately, identifying its cause, much less a treatment, has proven elusive. Now, however, a new study published in PLOS Biology may have uncovered the physiological mechanism behind it: neuroinflammation in the auditory cortex. And it could be treatable.
Note the "may" in the paragraph above. It's there because this study draws its conclusions based on the physiology of rodent test subjects, not humans, and things don't always translate between species. Hence, its claims deserve a grain or two of salt. Ethics issues aside, this is often the case with exciting-sounding medical-breakthrough news. It's so common, in fact, that there's a Twitter hashtag for it: @justsaysinmice.
How to acquire tinnitus
Not that you'd want to. However, the recipe is simple: Expose your ears to overloud noise. Tinnitus is actually not an underlying condition — it's a symptom of hearing loss. Noise-induced hearing loss (NIHL) can result from, for example, working in a loud environment without protecting your ears, or attending too many loud concerts, standing too close to speakers at a show, or from listening to loud music on headphones.
The way that we hear sound is not as direct as many think. Sound is really a matter of compression waves generated by a source that compresses and releases air on its way to your ears. Tiny hairs, the stereocilia, in your ears receive these air-pressure changes and fire off signals to your brain that we interpret as sound. Each hair has the job of producing a certain range of audio frequencies, and with tinnitus, some of these hairs get stuck in what amounts to their "on" position, continually firing off these signals to your brain even without the presence of an actual external sound source. Exactly what triggers this misbehavior is what the new study attempts to explain.
Image source: Alila Medical Media/Shutterstock
The study states, "Neuroinflammation is the central nervous system's response to external and internal insults, such as infection, injury, diseases, and abnormal neural activity," and so its authors looked at mice with NIHL to assess its possible role in tinnitus. They conclude "Our results indicate that neuroinflammation plays an essential role in a noise-induced excitatory-to-inhibitory synaptic imbalance and tinnitus in a rodent model."
To protect the brain, an inflammatory response typically involves the activation of microglia, the central nervous system's primary immune cells. When they remain active in response to chronic damage — as with hearing damage — though, they tend to release proinflammatory cytokines, which can make the problem worse. In the mice studies, the authors found one such proinflammatory cytokine, TNF-α. ("TNF" stands for "tumor necrosis factor.") It seems to be the neural trigger for tinnitus.
When the researchers shut off the gene that results in the production of TNF-α in one set of mice, and likewise when they repressed it with medication in another, tinnitus disappeared. Testing the connection from the other direction, they also found that when they introduced TNF-α into the auditory cortex of normal mice and also mice who had no natural TNF-α, tinnitus appeared.
How do we know if a mouse has tinnitus?
Image source: photolinc/Shutterstock
This question, which may have occurred to you to wonder, highlights a potential problem with this study. Since tinnitus is an ever-present phenomenon, some in the research community — including the authors of this study — have embraced "gap detection" as a means of testing for the presence of the condition in animals. The idea of gap testing is that, since tinnitus is constant, an animal wouldn't be able to hear gaps between a series of audio tones being played. Gap detection is tested by monitoring an animal's acoustic startle reflex to each new tone as it sounds — in theory, an animal with tinnitus won't notice or react to each new tone. However, it's worth noting that the value of gap detection testing for tinnitus is controversial.
All that having been said, there are a number of anti-inflammatory medications, and as used in the research, genetic means of controlling the presence of TNF-α. If the authors' findings are eventually confirmed to be valid in human subjects, there may be hope for tinnitus sufferers at last.
- Tinnitus cure - Is there a cure for tinnitus? How to stop tinnitus ›
- Tinnitus: Ringing in the ears and what to do about it - Harvard Health ›
- Tinnitus is the result of the brain trying, but failing, to repair itself ... ›
- Reducing brain inflammation could treat tinnitus and other hearing ... ›
- Treating brain inflammation could help silence tinnitus ›
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A neuroscientist argues that da Vinci shared a disorder with Picasso and Rembrandt.
- A neuroscientist at the City University of London proposes that Leonardo da Vinci may have had exotropia, allowing him to see the world with impaired depth perception.
- If true, it means that Da Vinci would have been able to see the images he wanted to paint as they would have appeared on a flat surface.
- The finding reminds us that sometimes looking at the world in a different way can have fantastic results.
The study<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xODc3Mjc2NS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1MTA4MDg2NH0.T-98YvLjS9mUCQkgqHyV43Q7h_JIiubrev-Fp_0j4Pg/img.jpg?width=1245&coordinates=0%2C38%2C0%2C579&height=700" id="58346" class="rm-shortcode" data-rm-shortcode-id="674799ba34e115a2e9a3e94c366bfc26" data-rm-shortcode-name="rebelmouse-image" />
The Virtuvian Man. Christopher Tyler suggests that Da Vinci used his own image as a template for the face in the drawing.
Vitruvian Man, by Leonardo da Vinci created c. 1480–1490<p><a href="https://www.city.ac.uk/people/academics/christopher-tyler" target="_blank">Professor Christopher Tyler</a> of the City University of London's optometry division analyzed six pieces of Renaissance art by or held to be images of Da Vinci, including the famous <em>Vitruvian Man. </em>By looking at the paintings, drawings, and statues and applying the same techniques optometrists use on patients, Tyler was able to conclude that the eyes of the men depicted were misaligned.</p><p> He concluded that, if the images he analyzed were truly reflective of how Da Vinci looked, that the great artist had a mild case of exotropia. </p>
How would this have helped him paint?<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="b221010aa7688734d4d6a41f0df5933f"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/j6F-sHhmfrY?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p><a href="https://shileyeye.ucsd.edu/faculty/shira-robbins" target="_blank">Shira Robbins</a>, a professor of ophthalmology at the University of California at San Diego, who was not involved with the project, explained to <em><a href="https://www.washingtonpost.com/news/morning-mix/wp/2018/10/19/leonardo-da-vincis-genius-may-be-rooted-in-a-common-eye-disorder-new-study-says/?utm_term=.d3f44ed91c16" target="_blank">The Washington Post</a> </em>how individuals with exotropia often turn to additional information to help understand the world around them:</p><blockquote>"What happens in some people is when they're only using one eye . . . they develop other cues besides traditional depth perception to understand where things are in space, looking at color and shadow in a way that most of us who use both eyes at a time don't really appreciate." </blockquote><p>Dr. Robbins agrees that, if the artworks analyzed accurately depict Da Vinci, then he probably had exotropia.</p><p>If Da Vinci did have a mild form of the condition, which would allow him to focus with both eyes when concentrating and with one when relaxed, Tyler asserts that the famed artist could have viewed the world in two or three dimensions at will, showing him the world exactly as he would need to recreate it on a flat surface. Quite the superpower for an artist.</p>
Does this mean Da Vinci would have been a hack if he had normal eyesight?<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xODc3MjY5NS9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTYyMjYwOTgxOH0.eSu3YBpCuaDj59-4lzSeZ1WgwtV2ETGiWHqczzW3how/img.png?width=980" id="9c323" class="rm-shortcode" data-rm-shortcode-id="edd4e9e9d9c1156a53242df6288d7cc0" data-rm-shortcode-name="rebelmouse-image" />
A graph showing the difference in where each eye is focused for each painting, drawing, and statue used in the study. The larger the difference, the more pronounced the exotropia is in the image.<p>Not at all. What Dr. Tyler is suggesting is that the tendency of people who have exotropia to rely on using one eye to see the world and thereby lose some depth perception allowed Da Vinci to understand better how the three-dimensional objects in the world could be translated into a two-dimensional image on a canvas. This could account for some of Da Vinci's skill in depicting shadow and subtle changes in color, since he would have relied on these details to understand the world. <br><br>His polymathic brilliance extended far beyond art, and nobody is claiming that his ideas for flying machines, tanks, or <a href="http://www.da-vinci-inventions.com/davinci-inventions.aspx" target="_blank">other inventions </a>were at all influenced by a vision problem.</p>
How can we know this? He has been dead for five hundred years.<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="c26fc51b0aebbcd6905593015fec79e5"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/LRAptNtN9-A?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>There are reasons to be cautious anytime we make claims about people who are long dead. In this case, we have the bonus problem that we aren't 100 percent sure that the images used are supposed to look like Da Vinci. </p><p> That is the major caveat of the idea; all of the images used as evidence of his condition are assumed to look like him. While some of the images, like the <a href="https://en.wikipedia.org/wiki/David_(Verrocchio)" target="_blank"><em>David</em> by Andrea del Verrocchio</a>, are generally agreed to be based on Leonardo the other pictures are claimed to be reflective of him based only on his statement that "[The soul] guides the painter's arm and makes him reproduce himself, since it appears to the soul that this is the best way to represent a human being." </p><p>Tyler also argues that the portraits he claims are based on Da Vinci share similarities with the images generally accepted to be portraits of him; including similar hair and facial features. This lends weight to the idea that the artist incorporated his own traits into his artwork, including his vision problem. </p><p>Leonardo da Vinci was undoubtedly one of the greatest geniuses of all time. If he had exotropia, then it was merely a minor addition to his artistic skills. It does, however, give us a literal example of how people who look at the world differently can use that vantage point to their advantage to create things we all can appreciate. </p>
Want help raising your kids? Spend more time at church, says new study.
- Religious people tend to have more children than secular people, but why remains unknown.
- A new study suggests that the social circles provided by regular church going make raising kids easier.
- Conversely, having a large secular social group made women less likely to have children.
Be fruitful and multiply<p>Scientists in the United Kingdom collected data on more than 13,000 mothers and their children. Most of them were religious, but 12 percent were not. The data included information on their church habits, social networks, number of children, and the scores those children achieved on a standardized test.</p><p>In line with previous findings that religious women have more children than secular women in industrialized countries, a connection between at least monthly church attendance and fertility was confirmed. However, religious parents showed they could avoid the pitfalls that having more children can bring. </p><p>Typically, more children in a family leads to reduced cognitive ability and height in each <a href="https://academic.oup.com/ije/article/37/6/1408/729795" target="_blank">child</a>. Some studies find that children do less well in school for each <a href="https://link.springer.com/article/10.1007/s13524-016-0471-0" target="_blank">additional sibling they have</a>. This makes a kind of intuitive sense, as parents with more children would have to divide their time, energy, and resources among more people as families expand. One would expect that the larger families would also lead to things like lower test scores. </p><p>Despite the expectation, the children of religious parents didn't have lower scores on standardized tests. There were small positive relationships between the size of the mother's social network, the number of co-religionists helping out, and the children's test scores. However, this association was small, didn't show up in all of the testings, and was unrelated to other variables. </p> These effects might be explained by the size and helpfulness of the social networks around the more religious. Women who went to church at least once a month had more extensive social networks than those who never go or who attend yearly. These social networks of co-religious people mean that there are more people to turn to for help with child-rearing, a point also demonstrated in the data. The amount of aid women got from their fellow churchgoers was also associated with a higher fertility rate. <br> <br> Conversely, an extensive social network was associated with fewer children for secular women. This finding is in line with <a href="https://journals.sagepub.com/doi/10.1207/s15327957pspr0904_5" target="_blank">previous studies</a> and suggests that the social networks comprised of co-religious individuals differ from those found elsewhere.
So, how quickly should I join a local religious group?<div class="rm-shortcode" data-media_id="6RrmYM8M" data-player_id="FvQKszTI" data-rm-shortcode-id="9eb4740a7d1e10108a75fd2ed627a90f"> <div id="botr_6RrmYM8M_FvQKszTI_div" class="jwplayer-media" data-jwplayer-video-src="https://content.jwplatform.com/players/6RrmYM8M-FvQKszTI.js"> <img src="https://cdn.jwplayer.com/thumbs/6RrmYM8M-1920.jpg" class="jwplayer-media-preview" /> </div> <script src="https://content.jwplatform.com/players/6RrmYM8M-FvQKszTI.js"></script> </div> <p>The study is not without its faults, and more investigations into the relationship between fertility, childcare, ritual, and social networks are needed.</p><p>These findings all show correlation, not causation. Though it might be said the results point towards causation, various alternative interpretations of the data are apparent. The authors note that most religions are explicitly pro-natal. It is possible that religious women have internalized these values and simply choose to have more children than secular women do.</p><p>This idea is similar to a potential interpretation of why large social networks have the opposite effect for secular women. The authors suggest that, in some cases, these more extensive social networks are associated with work and exert an anti-natal influence. Again, the people who build such networks may be people unlikely to have large families under any circumstances.</p><p>However, the researchers' hypothesis endured. The help religious women get from their church-based social networks allows them to have larger families than those who lack these support systems. In some instances, these support systems also prevent the adverse effects of larger families. </p>
The community religion offers<p>As we've mentioned <a href="https://bigthink.com/culture-religion/what-is-secular-humanism" target="_blank">before</a>, religion offers a community, and a community provides social capital. As religion continues to decline in the West, the social bonds of faith communities that used to tie social communities together begin to decay. However, as has been noted by a variety of observers for the last few decades, fewer and fewer new organizations appear ready to replace religion as a source of community in our lives.</p><p>While many different organizations might offer social support that religion once provided the whole of western society, this study shows that different social circles can differently affect the people in them. This finding must be considered by those trying to find new communities to join or the authors of future research. </p><p>The community offered by religious groups provides real benefits to those who join them. As this study shows, having the support network religious community offers allows some parents to avoid pitfalls that bedevil those lacking similar support. It suggests that previous studies demonstrating that group ritual offers benefits like increased amounts of <a href="https://journals.sagepub.com/doi/10.1177/0956797612472910" target="_blank">group trust</a> and <a href="https://journals.sagepub.com/doi/10.1177/1069397103037002003" target="_blank">cooperation</a> are onto something and that those benefits have a variety of applications. </p><p>While this study is not without its blind spots, it offers a strong starting point for further investigations into the nature of ritual in our modern lives and how local support networks remain vital in our increasingly globalized world. </p>
Health officials in China reported that a man was infected with bubonic plague, the infectious disease that caused the Black Death.
- The case was reported in the city of Bayannur, which has issued a level-three plague prevention warning.
- Modern antibiotics can effectively treat bubonic plague, which spreads mainly by fleas.
- Chinese health officials are also monitoring a newly discovered type of swine flu that has the potential to develop into a pandemic virus.
Bacteria under microscope
needpix.com<p>Today, bubonic plague can be treated effectively with antibiotics.</p><p style="margin-left: 20px;">"Unlike in the 14th century, we now have an understanding of how this disease is transmitted," Dr. Shanthi Kappagoda, an infectious disease physician at Stanford Health Care, told <a href="https://www.healthline.com/health-news/seriously-dont-worry-about-the-plague#Heres-how-the-plague-spreads" target="_blank">Healthline</a>. "We know how to prevent it — avoid handling sick or dead animals in areas where there is transmission. We are also able to treat patients who are infected with effective antibiotics, and can give antibiotics to people who may have been exposed to the bacteria [and] prevent them [from] getting sick."</p>
This plague patient is displaying a swollen, ruptured inguinal lymph node, or buboe.
Centers for Disease Control and Prevention<p>Still, hundreds of people develop bubonic plague every year. In the U.S., a handful of cases occur annually, particularly in New Mexico, Arizona and Colorado, <a href="https://www.cdc.gov/plague/faq/index.html" target="_blank">where habitats allow the bacteria to spread more easily among wild rodent populations</a>. But these cases are very rare, mainly because you need to be in close contact with rodents in order to get infected. And though plague can spread from human to human, this <a href="https://www.healthline.com/health-news/seriously-dont-worry-about-the-plague#Heres-how-the-plague-spreads" target="_blank">only occurs with pneumonic plague</a>, and transmission is also rare.</p>