For most animals, the scent of rotting meat is powerfully repulsive. But for others, such as carrion-feeding vultures and insects, it’s a scent that can be just as powerfully attractive.The question of why some animals are repelled and others attracted to a particular scent, scientists say, gets at one of the most basic and poorly understood mysteries in neuroscience: How does the brain encode likes and dislikes?Harvard scientists say they’re closer to unraveling that question with the discovery of the first receptors in any species evolved to detect cadaverine and, two of the chemical byproducts responsible for the distinctive — and to most creatures repulsive — smell of rotting flesh. The study is described in a paper published in the Proceedings of the National Academy of Sciences.“This is the first time we’ve identified a receptor for these chemicals,” said Associate Professor of Cell Biology Stephen Liberles, a senior author of the paper. “The larger question we’re interested in is: What does it mean that something is an aversive or attractive odor? How are likes and dislikes encoded in the brain? Understanding the receptors that respond to those cues could give us a powerful inroad to understanding that.”Graduate School of Arts and Sciences student Zecai Liang with Liberles in his lab. Liberles is trying to unravel the scent question: How are likes and dislikes encoded in the brain?Though researchers have long understood that olfaction involves receptors, which detect odors and in turn activate brain neurons, Liberles, together with Nobel laureate Linda Buck, recently discovered a second family of receptors, dubbed trace amine-associated receptors, or TAARs.Though fewer in number than other odorant receptors — mice, for example, have 15, versus more than 1,000 odorant receptors, while humans have 350 receptors and just six TAARs — Liberles said the functions of the TAARs remained largely unknown.“We knew they were olfactory receptors, but we didn’t know what ligands might activate them,” Liberles said of the TAARs. “We know in the taste system there are different families of receptors for bitter and sweet, so we thought the TAARs might be doing something specific in olfaction.”To understand how the TAARs function, researchers sought to identify scents that would activate them, hoping they might offer clues into why a second olfactory system evolved. In recent years, scientists working in Liberles’ lab identified odors that activated six TAARs in mice and seven in rats, nearly all of which were highly aversive.To check TAARs in fish, Liberles’ team worked with colleagues in Germany to implant olfactory receptors in cell cultures and test them against hundreds of possible odorants, hoping to identify which ones activated the receptor.What the researchers discovered, Liberles said, was that one particular receptor appeared to act as a sensor for diamines — a class of chemicals that include cadaverine and putrescine — nearly all of which are notoriously foul-smelling. Later tests using live zebrafish showed that when researchers marked part of a fish tank with the scent of rotting fish, the fish were highly likely to avoid the area.“What’s also interesting is that this odor — like the predator odor we identified in mice — was aversive the very first time the animal encountered it,” Liberles said. “That suggests the aversion is innate — it’s not learned — and that it involves genetic circuits that are genetically predetermined, that exist, dormant, in the animal waiting for it to encounter the odor.“You might like the smell of baking cookies, but it’s only because you’ve learned to associate it with their taste, or the sugar rush you get from eating them,” he continued. “But this aversion is there from birth. That suggests there is some developmental mechanism underlying these circuits. The question is, what is that?”Though researchers have thus far only shown that the TAARs are activated by amines, Liberles said it’s unlikely that is their only role in olfaction.“We’ve been hunting for a unified theme for what the TAARs might be doing,” he said. “One model is that they’re amine receptors, and another is that they’re all encoding for aversion. I don’t think either is quite correct. I think they may have started as amine receptors, but they have since evolved to do other things.”Understanding how odorants like cadaverine and putrescine work in the olfactory system could also shed light on why some scents — such as rotting meat — repel some creatures, but attract others.“Species-specific behavioral responses suggest that somehow the neural circuits are changing from species to species,” Liberles said. “For instance, tests in our lab have shown that trimethylamine is attractive to mice, but highly aversive to rats. Something similar might be happening with cadaverine.“How does that happen? It’s not known,” he continued. “We don’t understand, as a field, how aversive and attractive odors are differentially processed … but identifying the receptor gives us a handle on the neural circuits that are involved. Now that we have the receptor, we can ask basic questions about aversion and attraction circuitry in general. From there, we can begin to understand how attractive and aversive stimuli are differentially encoded, and cadaverine is about as aversive as you can get.” <a href=”https://www.youtube.com/watch?v=oaC2P7IU8dU” rel=”nofollow” target=”_blank”> <img src=”https://img.youtube.com/vi/oaC2P7IU8dU/0.jpg” alt=”0″ title=”How To Choose The Correct Channel Type For Your Video Content ” /> </a>
Newsroom GuidelinesNews TipsContact UsReport an Error AD Quality Auto 360p 720p 1080p Top articles1/5READ MOREUCLA alum Kenny Clark signs four-year contract extension with PackersFor the first time, there was a definitive window into how LeBron, who has detailed in so many ways how he wished “to be like Mike” growing up in poverty in Akron, Ohio, has watched the documentary series and how old memories of Jordan have resurfaced. On Monday on “WRTS: After Party,” a show produced by his media company Uninterrupted, he dove into how he viewed Jordan as “Black Jesus,” a man who seemed like a god who lived in his television until he met him at 16 years old, watching him and Antoine Walker talk trash in a gym together. He imagined how his Redeem Team would fare against the classic 1992 Dream Team. At one point, he envisioned himself playing alongside Jordan in place of Scottie Pippen, saying it “would have been a whole ‘nother level.”But the other side – the more nuanced, more complicated one – came out, too. After ESPN’s Brian Windhorst wrote that James liked to imagine Jordan as a teammate rather than an adversary, LeBron tried to scrub the record. It’s not surprising that James, whose critics assail him for forming the Heatles in Miami in 2010 rather than following Jordan’s one-franchise path (oh, how quickly we forget those Wizard seasons), would be sensitive about people saying he’d rather join his Airness than challenge him. For as much as LeBron is willing to reminisce about how he idolized Jordan, this is still a competition: He doesn’t wish to live exclusively in Michael’s shadow.It’s a complicated relationship. James has said many times that Jordan was one of his most powerful male role models in his single-parent household as a child. He’s called Jordan his “inspiration,” and on the podcast, he detailed how devastating it was when Jordan retired the first time, leaving a 9-year-old James in tears.But by many accounts, the two men are not close. Perhaps meeting our idols is never quite what we hope. Jordan’s emotional tribute to Kobe Bryant in February, in once sense, underscores that he has a far less intimate relationship with James. Beyond competing legacies on the court, they also are somewhat competitors off it, given that the Jordan Brand is its own offshoot of Nike. James has aspirations of one day owning an NBA team as Jordan does. This is not to say LeBron doesn’t appreciate Jordan, or give him credit. On the show, LeBron and business associate Maverick Carter acknowledged there would be no LeBron without Michael. They noted that without Jordan’s relationship with Nike, LeBron wouldn’t have reaped his marketing platform. Without the Dream Team, basketball probably wouldn’t have launched LeBron into the global stardom he enjoys today.But there is some behind-the-scenes manuevering and posturing that feels a little frosty. ESPN reported that Jordan agreed to the documentary on the day James and the Cleveland Cavaliers were parading through Cleveland after the 2016 Finals. Perhaps this is coincidence.It’s also worth remembering that LeBron, though he often shies from comparing himself to Jordan in public forums, has self-declared as the best player of all time. Even though Jordan is famously reclusive and barely appears for public events anymore, that surely got back to his ears. It’s interesting how recency bias can help debates like this one ebb and flow: Jordan unleashing a 10-part series with ESPN, over which he had a great deal of control, has injected a fresh perspective on his legacy (albeit with maybe a little airbrushing over the bullying of his own teammates).The fact that the documentary comes in the vacuum of the NBA hiatus means Jordan has given himself a platform to celebrate his career while James’ own has stalled for forces beyond his control. James has come around slowly to engaging “The Last Dance” on social media. On the debut weekend, James didn’t post about the show on his Twitter or Instagram page – which seemed odd since he himself suggested back in March he hoped ESPN would release earlier than originally planned. He did manage to tweet about “The Wall,” a game show produced by one of his media companies.As the weeks went on, LeBron warmed up: posting about the emotion when he watched Jordan win his first title, then recalling how he cried when Jordan first retired. And by the end, he was engaged enough to film a 48-minute show around “The Last Dance,” and was pretty game to talk a lot about his childlike awe for the man he viewed as a real-life superhero.That doesn’t change the fact that two competitive men are surely being protective of their legacies, hoping to stake their individual claims as the greatest. There was one particular goosebumps moment of James’ reaction to show he reflected on how Jordan retired at the top of his game in 1998.“He’s nowhere near being on his last legs,” James said with wide eyes. “This (expletive) can still go. He’s still the best player in the world. And I’m watching that in ‘98 at 14 years of age, and I’m like, ‘Wow, Mike’s still the best player in the world at 35 years old.’”LeBron, age 35, is now forced away from the game while some still believe he’s the best player in the world. And after five weeks of watching Michael at his greatest, that has to sting.— Kyle GoonThese links are still open for businessAn opening for pro sports in California? – Gov. Gavin Newsom seemed to make some encouraging suggestions about pro sports in June (albeit without fans).Facilities open – The Lakers and Clippers have both tentatively opened facilities for individual workouts.No substances involved in helicopter crash – An autopsy report shows no signs of drugs or alcohol in the pilot who flew Kobe and Gigi Bryant in the fatal crash.The full ‘Last Dance’ reaction from LeBron – If you’re interested in viewing the 48-minute show, tune in to see what LeBron had to say about Michael.Dwight Howard dealing with grief – The mother of one of his children died during the quarantine, offering tough perspective for Howard and his family.Mamba out – The Sports Academy in Thousand Oaks is changing its name, removing “Mamba” from the title.Follow our COVID-19 news coverage – The latest on local cases and procedures to limit the pandemic. Editor’s note: This is the Tuesday, May 19 edition of the Purple & Bold Lakers newsletter. To receive the newsletter in your inbox, sign up here.Michael vs. LeBron? Let’s not kick the dead horse.Perhaps the most popular, most heated and most exhausted debate in basketball is getting microwaved again by “The Last Dance,” which finished airing on ESPN on Sunday with episodes nine and ten. But rather than trodding upon ground that’s already well covered, I find myself wondering:What must it be like for LeBron to have watched this documentary in an extraordinary moment like this?