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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 ›
Andy Samberg and Cristin Milioti get stuck in an infinite wedding time loop.
- Two wedding guests discover they're trapped in an infinite time loop, waking up in Palm Springs over and over and over.
- As the reality of their situation sets in, Nyles and Sarah decide to enjoy the repetitive awakenings.
- The film is perfectly timed for a world sheltering at home during a pandemic.
In more than a dozen countries as far apart as Portugal and Russia, 'Smith' is the most popular occupational surname
- 'Smith' is not just the most common surname in many English-speaking countries
- In local translations, it's also the most common occupational surname in a large part of Europe
- Ironically, Smiths are so ubiquitous today because smiths were so special a few centuries ago
Meet the Smiths, Millers, Priests and Imams - the most popular occupational surnames across Europe.
Image: Marcin Ciura<p>Although very few people are smiths by profession these days, there are millions of Smiths by surname the world over. It's the most popular surname in Britain, Australia, New Zealand and the United States, as well as the second most popular surname in Canada and the fifth most popular one in Ireland. And they're a thriving bunch, at least in the U.S.: the 2010 Census (1) counted 2,442,977 Americans called Smith, 2.8% more than in 2000.</p><p>Curiously, 'Smith' also is one of the most popular surnames across most of Europe –translated in the various local vernaculars, of course. This map shows the most common occupational surnames in each country. By colour-coding the professions, this map shows a remarkable pro-smith consistency across Europe – as well as some curious regional exceptions.</p>
‘Smith’ popular throughout Europe<p>'Smith', in all its variations, is the most popular occupational surname throughout Europe. Not just in the UK, but also in:</p> <ul><li>Belgium (<em>Desmet</em>) and Luxembourg, (<em>Schmitt</em>);</li> <li>France (<em>Lefebvre</em>), Italy (<em>Ferrari</em>) and Portugal (<em>Ferreira</em>);</li> <li>Slovenia (<em>Kovačič</em>), Croatia (<em>Kovačevič</em>), Hungary (<em>Kovács</em>), Slovakia (<em>Kováč</em>), Poland (<em>Kowalski</em>), Lithuania (<em>Kavaliauskas</em>), Latvia (<em>Kalējs</em>) and Belarus (<em>Kavalyov</em>);</li> <li>Estonia (<em>Sepp</em>); and</li> <li>Russia (<em>Kuznetsov</em>).</li></ul>
‘Miller’ on top in many Germanic-language countries<p>'Miller' is the most popular occupational surname in many Germanic-language countries, but also in Spain and Ukraine (perhaps because the grain in both countries is mainly in the plain):</p> <ul><li>There's <em>Müller</em> (in Germany and Switzerland), <em>M</em><em>ø</em><em>ller</em> (in Denmark and Norway) and <em>Möller</em> (Sweden);</li> <li><em>Molina</em> (in Spain – the map also shows the most popular surname in Catalonia/Catalan: <em>Ferrer</em>, i.e. 'Smith'); and</li> <li><em>Melnik</em> (in Ukraine).</li></ul>
Clergy surnames rule in the Balkans<p>Catholic clergy must remain celibate, so 'Priest' as a surname is rare to non-existent throughout Europe. Except in the Balkans, where Catholicism is largely absent. Here, the Orthodox and Islamic clergies have passed on the title from father to son, eventually as a surname, to popular effect. Orthodox clergy are addressed as <em>papa</em> or <em>pope</em> (which means 'father' – so the surname rather redundantly translates to 'father's son'). Islamic teachers or imams are known by the Turkish/Persian term <em>hodzha</em>. An overview:</p> <ul><li><em>Popov</em> (in Bulgaria), <em>Popovic</em> (in both Serbia and Montenegro), <em>Popovski</em> (in Macedonia);</li> <li><em>Popa</em> (in Romania); </li> <li><em>Papadopoulos</em> (in Greece); and</li> <li><em>Hodžić</em> (in Bosnia-Herzegovina), <em>Hoxha</em> (in both Kosovo and Albania).</li></ul>
Landowners and other professions<p>Austria and the Czech Republic have different national languages but are neighbours and share a lot of history. Could that explain why they have a similar most popular occupational surname, for 'landowner'?</p> <ul><li><em>Huber</em> (in Austria) and</li> <li><em>Dvořák</em> (in the Czech Republic).</li></ul> <p>Just four professions, that wraps up all but five countries on this map. Those five each have their very own most popular occupational surname:</p> <ul><li><em>Bakker</em> (in the Netherlands): 'Baker'</li> <li><em>Kinnunen</em> (in Finland): 'Skinner'</li> <li><em>Ceban</em> (in Moldova): 'Shepherd'</li> <li><em>Avci</em> (in Turkey): 'Hunter'</li> <li><em>Murphy</em> (in Ireland): 'Sea Warrior' </li></ul>
Even more Smiths<p>Judging from the popularity of these surnames, your generic European village of a few centuries ago really couldn't do without a smithy. It was a much more essential craft even than that of the miller (or the baker, who put the miller's flour to good use) – except in the Balkans, where spiritual sustenance apparently sated a greater need. On the outskirts of <em>Anytown, Europe</em> live the shepherd and the hunter, the skinner and the pirate.<br></p><p>A bit too simplistic? Perhaps not simplistic enough. This map could have been dominated by even more Smiths. As the original poster explains, he always picked the most frequent version of an occupational surname, even if multiple variants point to a more popular alternative. </p><p>In the Netherlands, for instance, people with the surnames <em>Smit, Smits, Smid, de Smit, Smet </em>and <em>Smith</em> collectively outnumber those with the surnames <em>Bakker, Bekker, de Bakker</em> and <em>Backer</em>. So, the Netherlands could be considered another win for 'Smith' – except that the variant <em>Bakker</em> is more frequent than any other single variant.</p><p>Same story in Germany: added up, there are more people named <em>Schmidt, Schmitt, Schmitz </em>and <em>Schmid</em> than <em>Müller</em>. Ditto for Spain: <em>Herrero, Herrera </em>and <em>Ferrer</em> together outnumber <em>Molina</em>. Also in Finland, where <em>Seppä</em>, <em>Seppälä</em> and <em>Seppänen</em> together have a higher count than <em>Kinnunen</em>. </p>
Smiths in other cultures<p>'Smith' was a crucial occupation in other cultures too, judging from the familiar ring it has in these languages:<br></p><ul><li><em></em><em>Demirci</em> (Turkish)</li><li><em>Hadad</em> (Syriac, Aramaic, Arabic)</li><li><em>Nalbani</em> (Albanian)</li><li><em>McGowan</em> (Gaelic)</li><li><em>Faber</em> (Latin)<span></span></li></ul>
Other most popular surnames<p>Take note, though: 'Smith' may be the most popular surname in in the Anglosphere, this map does not mean to show that its variants in French, Russian and other languages also are the most popular surnames in the countries marked grey. They are merely the most popular <em>occupational</em> surnames.<br></p><p>As this sample of most common ones for each country shows, surnames can refer to a host of other things. Personal qualities or physical attributes, for example:</p> <ul><li>Russia: <em>Smirnov</em> ('the quiet one')</li> <li>Turkey: <em>Yilmaz</em> ('unflinching')</li> <li>Hungary: <em>Nagy</em> ('big')</li> <li>Italy: <em>Rossi/Russo</em> ('red', in northern and southern Italy, respectively)</li></ul> <p>Another option: the origin of the name-bearer (be it a place or a person):</p> <ul><li>Sweden: <em>Andersson</em> ('son of Anders')</li> <li>Slovakia: <em>Horvath</em> ('Croat')</li> <li>Kosovo: <em>Krasniqi</em> (refers to the Krasniq tribe and their mountainous home region)</li> <li>Portugal: <em>Silva</em> ('woodland')</li> <li>Latvia: <em>Bērziņš</em> ('little birch tree')</li> <li>Estonia: <em>Tamm</em> ('oak')</li></ul> <p>But sometimes, even for the most popular ones, the exact origin of the surname is lost in time:</p> <ul><li>Spain: <em>Garcia</em> (originally Basque, possibly meaning 'young', 'bear' or 'young bear')</li> <li>Finland: <em>Korhonen</em> ('hard of hearing' or 'dim-witted'; 'village elder'; 'proud'; 'upright'). </li></ul>
Smith popularity theory<p>So why exactly is Smith – and not Miller, for example – the most popular surname in many English-speaking countries? The theory propounded by historian C.M. Matthews in <em>History Today</em> (July 1967) probably also holds for the other-language variants so popular throughout Europe:<br></p><blockquote>"The reason for (the) multiplicity (of the surname 'Smith') is not so much that metal-workers were numerous as that they were important and widespread. On the skill of the smith, both rich and poor depended for the most essential things of life, the tools of husbandry and the weapons of hunting and war. Every community in the land must have one, every castle, every manor; and so distinctive was his trade that he would seldom need another name".<em></em></blockquote><p>That does not mean all people with the surname have a forefather who forged iron into weapons and farm tools. Especially in North America, 'Smith' was adopted by many people precisely because it was already common – as a secret identity or to blend in, for example by natives, slaves and immigrants.</p>
A recent analysis of a 76-million-year-old Centrosaurus apertus fibula confirmed that dinosaurs suffered from cancer, too.
- The fibula was originally discovered in 1989, though at the time scientists believed the damaged bone had been fractured.
- After reanalyzing the bone, and comparing it with fibulas from a human and another dinosaur, a team of scientists confirmed that the dinosaur suffered from the bone cancer osteosarcoma.
- The study shows how modern techniques can help scientists learn about the ancient origins of diseases.
Centrosaurus apertus fibula
Royal Ontario Museum<p>In the recent study, the team used a combination of techniques to analyze the fibula, including taking CT scans, casting the bone and studying thin slices of it under a microscope. The analysis suggested that the dinosaur likely suffered from osteosarcoma, a type of bone cancer that affects modern humans, typically young adults.</p><p>For further evidence, the team compared the damaged fibula to a healthy fibula from a dinosaur of the same species, and also to a fibula that belonged to a 19-year-old human who suffered from osteosarcoma. Both comparisons supported the osteosarcoma diagnosis.</p>
Evans et al.<p style="margin-left: 20px;">"The shin bone shows aggressive cancer at an advanced stage," Evans said in a <a href="https://www.rom.on.ca/en/about-us/newsroom/press-releases/rare-malignant-cancer-diagnosed-in-a-dinosaur" target="_blank">press release</a>. "The cancer would have had crippling effects on the individual and made it very vulnerable to the formidable tyrannosaur predators of the time."</p><p style="margin-left: 20px;">"The fact that this plant-eating dinosaur lived in a large, protective herd may have allowed it to survive longer than it normally would have with such a devastating disease."</p><p>The fossilized fibula was originally unearthed in a bonebed alongside the remains of dozens of other <em>Centrosaurus </em><em>apertus</em>, suggesting the dinosaur didn't die from cancer, but from a flood that swept it away with its herd.</p>
Dinosaur fibula; the tumor mass is depicted in yellow.
Royal Ontario Museum/McMaster University<p>The new study highlights how modern techniques can help scientists learn more about the evolutionary origins of modern diseases, like cancer. It also shows that dinosaurs suffered through some of the same terrestrial afflictions humans face today.</p><p style="margin-left: 20px;">"Dinosaurs can seem like mythical creatures, but they were living, breathing animals that suffered through horrible injuries and diseases," Evans said, "and this discovery certainly makes them more real and helps bring them to life in that respect."</p>
Join the lauded author of Range in conversation with best-selling author and poker pro Maria Konnikova!
UPDATE: Unfortunately, Malcolm Gladwell was not able to make the live stream due to scheduling issues. Fortunately, David Epstein was able to jump in at a moment's notice. We hope you enjoy this great yet unexpected episode of Big Think Live. Our thanks to David and Maria for helping us deliver a show, it is much appreciated.