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‘Adversarial’ search for neural basis of consciousness yields first results

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NEW YORK CITY—Amidst rock music, a rap about consciousness, and the calling in of a 25-year-old drunken bet, camps backing two leading theories of how consciousness arises from the brain waited anxiously in a Greenwich village theater on Friday to hear who had won the first round of an ambitious “adversarial collaboration.” Three neutral judges chosen to help design the experiment and evaluate the results gave a qualified victory to advocates of the idea that consciousness is a feature of networks of neurons found at the back of the brain.

But the opposing camp is far from ready to concede. It still contends that consciousness emerges within the brain’s “executive” center, the prefrontal cortex. “The results ended up challenging both [groups], with key predictions of the two theories being disconfirmed by the data,” says Liad Mudrik, a cognitive neuroscientist at Tel Aviv University and one of the judges of the scientific showdown.

The unusual evening event, part of the annual meeting of the Association for the Scientific Study of Consciousness (ASSC), also served as the denouement of a wager placed in 1998 at the second such conference. There, cognitive neuroscientist Christof Koch bet philosopher David Chalmers that the neural correlates of consciousness would be nailed down in 25 years. Drawing on the new experimental results, Koch yesterday conceded that those correlates remain unclear and on a stage gallantly offered up a bottle of 1978 Madeira to Chalmers, with five more fine reds in the wings.

David Chalmers (left) accepting the spoils of his consciousness bet with Christof Koch

For the collaboration, funded by the Templeton World Charity Foundation (TWCF), both sides of the consciousness debate agreed on experiments to be conducted by “theory-neutral” labs with no stake in the outcome. It pits Integrated Information Theory (IIT), the sensory network hypothesis that proposes a posterior “hot zone” as the site of consciousness, against the Global Neuronal Workspace Theory (GNWT), which likens networks of neurons in the front of the brain to a clipboard where sensory signals, thoughts and memories combine before being broadcast across the brain.

On balance, the three judges assessing the initial experiments gave more points to IIT, and its advocates were ready to declare victory. “The results corroborate IIT’s overall claim that posterior cortical areas are sufficient for consciousness, and neither the involvement of [the prefrontal cortex] nor global broadcasting are necessary,” said Melanie Boly, a neurologist and neuroscientist at the University of Wisconsin and a leading proponent of IIT.

But GNWT’s stoic chief architect, Stanislas Dehaene, Director of the INSERM-CEA Cognitive Neuroimaging Unit in Orsay, France, believes the this experimental round had limitations and the results of other tests in the adversarial collaboration–still to be announced–will support the role of the prefrontal cortex. He adds that the new findings locating conscious perception to the back of the brain are predicted by lots of theories, and don’t confirm the specifics of IIT.

Consciousness has compelled philosophers since Plato, but over the last three decades, neuroscientists have entered the fray. Both disciplines seek a working theory of consciousness as the first step towards measuring the phenomenon–whether to make life and death decisions about brain-damaged patients, ascribe rights to animals or determine whether AI may have it.

Among dozens of theories of consciousness, GNWT and IIT are among the most widely discussed. GNWT gained initial support from experiments that asked participants to report the moment they became aware of a stimulus, such as an image flashing on a screen. In those studies, many of them led by Dehaene, brain scans showed that the prefrontal cortex lit up at the moment of perception.

But philosophers and experimentalists questioned whether these studies captured the neural markers of conscious perception, or simply the task of reporting it. Cognitive processes such as paying attention and storing information in memory, both of which enable participants to respond that they’ve seen an image, are known to take place in the prefrontal cortex.

“No-report” studies, where participants passively view images, seemed to offer a workaround. A popular one involves binocular rivalry: if different images are shown to a person’s left and right eye, their conscious perception flips between them. These flips can be monitored—independent of participants’ report—by tracking eye movements. And lo, these experiments found signals of conscious perception at the back of the brain, the area predicted by IIT.

The front-of-brain camp fought back, arguing that these studies were themselves rife with confounders. For example, participants might be so wearied by staring at onscreen images that they stop paying attention to them and let their mind wander to other tasks, a phenomenon that New York University philosopher Ned Block dubbed the “bored monkey problem.”

It was this cauldron of contested evidence that fueled the adversarial collaboration. The project, launched in 2019, was the brainchild of Koch, then chief scientist at the Allen Institute and a proponent of IIT, and Dawid Potgieter, director of Discovery Science programs at TWCF, which committed 20 million dollars to a series of grants for adversarial collaborations testing theories of consciousness.

For the GNWT-versus-IIT phase of the project,Mudrik and the two other judges, psychologists Lucia Melloni at Max Planck Institute and Michael Pitts at Reed College  spent a year working closely with Dehaene and Giulio Tononi, a psychiatrist and neuroscientist at the University of Wisconsin and chief architect of IIT, to design two experiments for which each theory offered clearly distinct predictions. Dehaene and Tononi would have no role in performing the experiments or writing up the results.

The team preregistered the experimental design on an open science website and published the details last February. Six theory-neutral labs would scan the brains of 250 total participants using three techniques: functional magnetic resonance imaging, magnetoencephalography, and electrocorticography, in which electrodes are placed on the brain’s surface prior to a surgery.

The first of the two planned experiments showed participants images with and without an accompanying task—pressing a button in response to either of two target pictures—so researchers could look for differences in the resulting brain signals. IIT predicts that passive perception will activate the back of the brain, but perception while performing tasks will spark the front. GNWT predicts similar brain activation in the two situations.

Key to the experiment were algorithms called multivariate pattern decoders, which could predict which image a participant was viewing at a given time based on their brain signals. Researchers initially “trained” these decoders by feeding them examples of that participant’s brain activity data along with the corresponding image.

GNWT predicts that the frontal networks supporting both active and passive perception should be similar enough to allow the decoder to cross train. That is, if it’s been trained only on signals related to the task of passively observing a face, it should still be able to decode data from the task of pressing a button in response to a face. IIT predicts that cross training will only work well with brain signals from the posterior regions, the proposed site of conscious perception.

And that’s largely what the researchers found: outside of posterior regions, the decoders were not consistently able to switch between the tasked and passive data sets—a result that favors IIT.

But in another analysis, the tables were turned. During conscious perception, IIT predicts neural communication within posterior areas, while GNWT predicts it should be between visual and frontal zones. And in the study, “the expected communication patterns were in line with GNWT,” says Mudrik.

The timing of the recorded signals, meanwhile, offered stronger support for IIT. In the posterior region, activity persisted as long as the image was presented onscreen, as IIT predicts. GNWT instead predicts an initial spike of activity—the “ignition” of the frontal workspace—and another spike when the stimulus disappears. That theory scored a partial win: there was evidence for an initial spike, but not the “off” spike.

Dehaene says the design of the experiment compromised the sensitivity of signal decoding from the front of the brain that would have supported GNWT. It was, he says, a design that Tononi was keen on. In a trade-off, Dahaene scored his preferred design for the subsequent TWCF-funded experiment, which the research team hopes to present at next year’s ASSC meeting. Using a customized video game to distract participants, this experiment will isolate neural signals of conscious perception by comparing brain signals when subjects are aware of seeing an image and when they’re not.

Although Koch’s favored theory now has a leg up on GNWT, he says the continuing doubts around the new results were enough to pay off the bet to Chalmers. “I’ve lost the battle,” he declared onstage, “but won the war for science.”

 

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Here’s how Helene and other storms dumped a whopping 40 trillion gallons of rain on the South

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More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.

That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.

“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”

The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.

Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.

Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.

Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.

Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.

Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.

“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”

The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.

North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.

Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”

Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.

Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.

For Dello, the “fingerprints of climate change” were clear.

“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”

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Follow AP’s climate coverage at https://apnews.com/hub/climate

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Follow Seth Borenstein on Twitter at @borenbears

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Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

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‘Big Sam’: Paleontologists unearth giant skull of Pachyrhinosaurus in Alberta

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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.

On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.

They call it “Big Sam.”

The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.

It didn’t die alone.

“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.

She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”

“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.

The head alone, she said, is about the size of a baby elephant.

The discovery was a long time coming.

The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.

“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.

When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”

“It contains about 100 to 300 bones per square metre,” she said.

Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.

About a year ago, they found the second adult: Big Sam.

Bamforth said both dinosaurs are believed to have been the elders in the herd.

“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.

“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”

The genders of the two adults are unknown.

Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.

The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.

She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.

“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.

“It’s pretty exciting.”

This report by The Canadian Press was first published Sept. 25, 2024.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

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