It’s hard for us to accept the idea that the brain stops growing, despite the large body of scientific evidence supporting this idea. The often-repeated statistic, based on years of research, is that the brain stops developing around the age of 25. More recently, an international team of neuroscientists argued in Nature that the human brain stops producing new neurons at age 13. The response from the scientific community to this most recent study has been significant, to say the least.

In their paper, published Wednesday, the researchers write that their findings “do not support the notion that robust adult neurogenesis continues in the human hippocampus.” In other words, none of the hippocampus tissue samples from adult brains they examined showed evidence of new neurons. Infants’ brains grow lots of new neurons, they report, and older children’s brains slow down a little. Meanwhile, none of their adult samples showed evidence of new neurons. And this is what other scientists don’t agree with.

“They may just not have looked carefully enough,” Jonas Frisén, Ph.D., of the Karolinska Institute in Sweden, told STAT News on Wednesday. Frisén co-authored a paper in 2015 that contradicts the findings of the Nature paper. And Frisén isn’t the only one who thinks these researchers’ conclusion may be premature.

This image shows new neurons (green) in the brains of an infant (left), a 13-year-old (middle), and a 35-year-old (right).

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“There is a long history of concluding that adult neurogenesis doesn’t exist in a given species based on difficulty in identifying new neurons,” Heather Cameron, Ph.D., a principal investigator of neuroplasticity at the National Institutes of Mental Health, told The Atlantic on Thursday. “This happened in rats and then in nonhuman primates, both of which are now universally acknowledged as showing adult hippocampal neurogenesis.”

One of the major difficulties in measuring neurogenesis in the brain is that you can’t observe it in real time. The researchers, therefore, had to settle for the next best thing: brains from recently deceased patients. Unfortunately, even when directly examining brains, the best you can do is look for molecular markers that could indicate new neurons.

“You can’t just shine light onto a skull and see it,” said Salk Institute neurobiologist Fred Gage, Ph.D., who studies adult neuroplasticity, in an interview with STAT News on Wednesday. Therefore, this evidence comes down to how it’s interpreted. That’s where the disagreement lies.

Many in the scientific community are contesting the finding that the brain stops making new neurons after age 13.

Despite the uproar, the authors of the paper stood by their findings. “If neurogenesis continues in adult humans, it’s extremely rare,” Arturo Alvarez-Buylla, Ph.D., a neuroscientist at University of California, San Francisco and one of the authors on the study, told The Atlantic. “It’s not as robust as what people have said, where you could go running and pump up the number of neurons.”

In recent studies, neuroscientists have demonstrated that human adult brains can indeed produce new neurons, specifically in the hippocampus, a region associated with working memory, so Alvarez-Buylla and his team will likely need much more evidence to convince the community that their findings are correct. Plenty of research has shown that neuron development drops off as people get older, but moving the finish line back to age 13 is huge. There might not be any closure to this argument yet, but future experiments will hopefully clarify exactly at what age human brains stop producing neurons — if they ever do.

On Monday, scientists revealed the first images of a human inside the world’s newest total body scanner, called EXPLORER. The name is fitting because this scanner really leaves absolutely nothing to the imagination, tracking the way drugs and disease progress through every nook and cranny in the body.

Designed by biomedical engineering professor Simon Cherry, Ph.D., and biophysicist Ramsey Badawi, Ph.D. at University of California, Davis, this scanner produces images that look like a hybrid between a PET scan (which is often used to find tumors) and an X-ray, all in ghostly black and white. But what’s interesting about EXPLORER, which will be officially unveiled at the Radiological Society of North America meeting on November 24th, isn’t that it produces detailed images of tissues or bones. Cherry tells Inverse that it can also create 3D movies showing where certain drugs may end up in the body.

While we all love sleeping there’s nothing more disgusting that what you’re sleeping in. Your sheets, by all conventional standards, are hosts for thousands of gross bacteria, fungi, sweat and bodily excretions that you sleep in every night. Worst part is that most people don’t wash their sheets nearly enough. While there are some that throw their dirty sheets in the laudry weekly, as recommended, most people can go weeks without it. They are lying in filth on a nightly basis and doing nothing about it.

Climate change often conjures up images of heat, drought, and hurricanes. But according to the latest US National Climate Assessment, released on Nov. 23, 2018, winters have warmed three times faster than summers in the Northeast in recent years. These changes are also producing significant effects.

Historically, over 50 percent of the northern hemisphere has had snow cover in winter. Now warmer temperatures are reducing the depth and duration of winter snow cover. Many people assume that winter is a dormant time for organisms in cold climates, but decades of research now show that winter climate conditions — particularly snowpack — are important regulators of the health of forest ecosystems and organisms that live in them.

After a 41-year journey, NASA’s Voyager 2 spacecraft is officially the second human-made object to leave our solar system. Researchers announced on Monday that on November 5, Voyager 2 broke through the heliosphere, the bubble of ionized particles that envelops the solar system. This spectacular outcome, the Voyager project scientists revealed at the fall meeting of the American Geophysical Union, was never guaranteed when the craft launched in 1977.