Thinking Energy - Ketamine Facts - Synaptic Partners - Semaglutide & Vision
Breedlove, S
https://www.quantamagazine.org/how-much-energy-does-it-take-to-think-20250604/
How Much Energy Does It Take To Think?
Myrian Wares for Quanta Magazine
You’ve just gotten home from an exhausting day. All you want to do is put your feet up and zone out to whatever is on television. Though the inactivity may feel like a well-earned rest, your brain is not just chilling. In fact, it is using nearly as much energy as it did during your stressful activity, according to recent research.
Sharna Jamadar (opens a new tab), a neuroscientist at Monash University in Australia, and her colleagues reviewed research from her lab and others around the world to estimate the metabolic cost of cognition (opens a new tab) — that is, how much energy it takes to power the human brain. Surprisingly, they concluded that effortful, goal-directed tasks use only 5% more energy than restful brain activity. In other words, we use our brain just a small fraction more when engaging in focused cognition than when the engine is idling.
It often feels as though we allocate our mental energy through strenuous attention and focus. But the new research builds on a growing understanding that the majority of the brain’s function goes to maintenance. While many neuroscientists have historically focused on active, outward cognition, such as attention, problem-solving, working memory and decision-making, it’s becoming clear that beneath the surface, our background processing is a hidden hive of activity. Our brains regulate our bodies’ key physiological systems, allocating resources where they’re needed as we consciously and subconsciously react to the demands of our ever-changing environments.
“There is this sentiment that the brain is for thinking,” said Jordan Theriault (opens a new tab), a neuroscientist at Northeastern University who was not involved in the new analysis. “Where, metabolically, [the brain’s function is] mostly spent on managing your body, regulating and coordinating between organs, managing this expensive system which it’s attached to, and navigating a complicated external environment.”
© 2025 Simons Foundation.
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https://www.nytimes.com/2025/06/06/health/ketamine-effects-anesthetic-elon-musk.html
What to Know About the Effects of Ketamine
By Andrew Jacobs and Jacey Fortin
News reports detailing Elon Musk’s drug use have prompted renewed attention to ketamine, a powerful anesthetic that has become increasingly popular as a therapy for treatment-resistant depression and other mental health issues.
Although Mr. Musk has acknowledged using ketamine in the past to treat depression, he has denied suggestions that he is currently using ketamine — or any other drug.
“I am NOT taking drugs!” he wrote last week in a social media post following the publication of an article in The New York Times that described reports of his use of drugs on the campaign trail last year. Those drugs included ketamine and other psychedelic compounds, among them MDMA and psilocybin mushrooms.
Mr. Musk left the White House last week. Since then, he and President Trump have traded barbs on social media over the president’s domestic policy bill and have mentioned government contracts with Mr. Musk’s companies and Mr. Musk’s relationship to the White House.
Mr. Trump, who was briefed on the article in The Times, has been telling associates in the last day or so that Musk’s “crazy” behavior is linked to his drug use, according to a Times report citing two people with knowledge of Mr. Trump’s private conversations. But later on Friday, Mr. Trump told reporters he did not want to comment on Mr. Musk’s drug use.
The very public feud between the two men has once again drawn unflattering attention to ketamine, a drug that has become increasingly available at legal clinics across the country. It is also used recreationally and can be dangerous when misused.
What is ketamine, and is it legal?
Ketamine is an injectable, short-acting dissociative anesthetic that can have hallucinogenic effects at certain doses. It distorts perceptions of sight and sound and makes users feel detached from pain and their surroundings.
© 2025 The New York Times Company
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How developing neurons simplify their search for a synaptic mate
By Calli McMurray
The hunt for a soulmate can be hard work—particularly for naive neurons. During development, the cells’ axons snake through burgeoning brain areas in search of the perfect dendrite to form a synapse with. Cell surface proteins serve as molecular identification tags to help axons distinguish “Mr. Wrong” dendrite from “Mr. Right,” according to the chemoaffinity hypothesis.
But there are too many cells and too few cell surface proteins for this to be the only strategy, says Claude Desplan, professor of biology and neural science at New York University. “There is no way you can find your partner in a big mess of many different thousands of types of neurons. So you do need to reduce the issue.”
In this brain region, 50 types of olfactory receptor neurons link up with 50 types of neurons that project to a sensory integration hub called the mushroom body; each synapse type bunches together inside the lobe to form its own distinct glomerulus. The axons of olfactory receptor neurons do not search the entire structure for their postsynaptic partner. Instead, the projection neurons inside the lobe send their dendrites to meet axons traveling along the surface. Once the two join up, they descend to their proper place in the lobe, imaging experiments show.
“Axons don’t need to delve deep. They only need to survey the surface in order to find their target,” says the study’s principal investigator, Liqun Luo, professor of biology at Stanford University. To make matters even simpler, the axons stick to a narrow, genetically determined trajectory, Luo says. Cortical regions may achieve a similar simplification through columns and layers: Axons travel to a certain brain region and then plunge to a particular depth, Luo suggests.
Genetically altering these trajectories precludes the olfactory receptor neurons from finding their proper mate, additional experiments show. Dendrites from the postsynaptic cell still wait for their partner at the surface, but “they will be sitting there waiting forever,” Luo says. Some cells “are still sticking their dendrites out” in adulthood, and in at least one case the team observed, a cell eventually matched with another partner.
© 2025 Simons Foundation
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Weight loss drugs linked to higher risk of eye damage in diabetic patients
Anna Bawden Health and social affairs correspondent
Weight loss drugs could at least double the risk of diabetic patients developing age-related macular degeneration, a large-scale study has found.
Originally developed for diabetes patients, glucagon-like peptide-1 receptor agonist (GLP-1 RA) medicines have transformed how obesity is treated and there is growing evidence of wider health benefits. They help reduce blood sugar levels, slow digestion and reduce appetite.
But a study by Canadian scientists published in Jama Ophthalmology has found that after six months of use GLP-1 RAs are associated with double the risk of older people with diabetes developing neovascular age-related macular degeneration compared with similar patients not taking the drugs.
Academics at the University of Toronto examined medical data for more than 1 million Ontario residents with a diagnosis of diabetes and identified 46,334 patients with an average age of 66 who were prescribed GLP-1 RAs. Nearly all (97.5%) were taking semaglutide, while 2.5% were on lixisenatide.
The study did not exclude any specific brand of drugs, but since Wegovy was only approved in Canada in November 2021, primarily for weight loss, it is likely the bulk of semaglutide users in the study were taking Ozempic, which is prescribed for diabetes.
Each patient on semaglutide or lixisenatide was matched with two patients who also had diabetes but were not taking the drugs, who shared similar characteristics such as age, gender and health conditions. The researchers then compared how many patients developed neovascular age-related macular degeneration over three years.
© 2025 Guardian News & Media Limited
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