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Brain-imaging study reveals curiosity as it emerges
You look up into the clear blue sky and see something you can’t quite identify. Is it a balloon? A plane? A UFO? You’re curious, right?
“Curiosity has deep biological origins,” said corresponding author Jacqueline Gottlieb, PhD, a principal investigator at the Zuckerman Institute. The primary evolutionary benefit of curiosity, she added, is to encourage living things to explore their world in ways that help them survive.
“What distinguishes human curiosity is that it drives us to explore much more broadly than other animals, and often just because we want to find things out, not because we are seeking a material reward or survival benefit,” said Dr. Gottlieb, who is also a professor of neuroscience at Columbia’s Vagelos College of Physicians and Surgeons. “This leads to a lot of our creativity.”
Joining Dr. Gottlieb on the research were Michael Cohanpour, PhD, a former graduate student at Columbia (now a data scientist with dsm-firmenich), and Mariam Aly, PhD, also previously at Columbia and now an acting associate professor of psychology at the University of California, Berkeley.
In the study, researchers employed a noninvasive, widely used technology to measure changes in the blood-oxygen levels in the brains of 32 volunteers. Called functional magnetic resonance imaging, or fMRI, the technology enabled the scientists to record how much oxygen different parts of the subjects’ brains consumed as they viewed images. The more oxygen a brain region consumes, the more active it is.
To unveil those brain areas involved in curiosity, the research team presented participants with special images known as texforms. These are images of objects, such as a walrus, frog, tank or hat, that have been distorted to various degrees to make them more or less difficult to recognize.
The researchers asked participants to rate their confidence and curiosity about each texform, and found that the two ratings were inversely related. The more confident subjects were that they knew what the texform depicts, the less curious they were about it. Conversely, the less confident subjects were that they could guess what the texform was, the more curious they were about it.
Three pairs of texforms showing unrecognizable and clear versions of objects. (Credit: Gottlieb Lab/Columbia’s Zuckerman Institute)
Using fMRI, the researchers then viewed what was happening in the brain as the subjects were presented with texforms. The brain-scan data showed high activity in the occipitotemporal cortex (OTC), a region located just above your ears, which has long been known to be involved in vision and in recognizing categories of objects. Based on previous studies, the researchers expected that when they presented participants with clear images, this brain region would show distinct activity patterns for animate and inanimate objects. “You can think of each pattern as a ‘barcode’ identifying the texform category,” Dr. Gottlied said.
The researchers used these patterns to develop a measure, which they dubbed “OTC uncertainty,” of how uncertain this cortical area was about the category of a distorted texform. They showed that, when subjects were less curious about a texform, their OTC activity corresponded to only one barcode, as if it clearly identified whether the image belonged to the animate or the inanimate category. In contrast, when subjects were more curious, their OTC had characteristics of both barcodes, as if it could not clearly identify the image category.
Also active during the texform presentations were two regions in the front of the brain. One is the anterior cingulate cortex, which previous studies implicated in information gathering. The other is the ventromedial prefrontal cortex (vmPFC), which is involved in monitoring a person’s subjective perceptions of value and confidence about different situations. In the new study, both areas were more active when subjects reported being more confident in knowing a texform’s identity (and thus, less curious to see the clarified image).
This is really the first time we can link the subjective feeling of curiosity about information to the way your brain represents that information.
Importantly, said Dr. Gottlieb, vmPFC activity seemed to provide a neurological bridge between the subjective feeling of curiosity and the OTC certainty measure. It’s as though this region read out the uncertainty encoded by the distributed activity pattern in the OTC and helped a person decide if they needed to be curious about the texform.
“This is really the first time we can link the subjective feeling of curiosity about information to the way your brain represents that information,” Dr. Gottlieb said.
The study has two important implications, Dr. Gottlieb said. First, although the study focused on perceptual curiosity elicited by visual stimuli, people experience other forms of curiosity, such as curiosity about trivia questions and factual matters (i.e. how tall is the Eiffel tower?) or social curiosity (which restaurant did my friends go to last night?). One intriguing possibility of the study, she noted, is that the mechanism it has uncovered may generalize to other forms of curiosity. For example, an fMRI study investigating sounds of varying recognizability may show that auditory areas in the brain convey the uncertainty regarding the sound and the vmPFC reads out this uncertainty to determine curiosity.
A second possibility on Dr. Gottlieb’s mind is that the findings could have diagnostic and even therapeutic implications for those with depression, apathy or anhedonia (the inability to feel pleasure), which are conditions often marked by a lack of curiosity.
“Curiosity entails a sort of enthusiasm, a willingness to expend energy and investigate your surroundings. And it’s intrinsically motivated, meaning that nobody is paying you to be curious; you are curious merely based on the hope that something good will come when you learn,” Dr. Gottlieb said. “Those are just some of the amazing things about curiosity.”
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Early dark energy could resolve cosmology’s two biggest puzzles
A new study by MIT physicists proposes that a mysterious force known as early dark energy could solve two of the biggest puzzles in cosmology and fill in some major gaps in our understanding of how the early universe evolved.
Now, the MIT team has found that both puzzles could be resolved if the early universe had one extra, fleeting ingredient: early dark energy. Dark energy is an unknown form of energy that physicists suspect is driving the expansion of the universe today. Early dark energy is a similar, hypothetical phenomenon that may have made only a brief appearance, influencing the expansion of the universe in its first moments before disappearing entirely.
Some physicists have suspected that early dark energy could be the key to solving the Hubble tension, as the mysterious force could accelerate the early expansion of the universe by an amount that would resolve the measurement mismatch.
The MIT researchers have now found that early dark energy could also explain the baffling number of bright galaxies that astronomers have observed in the early universe. In their new study, reported in the Monthly Notices of the Royal Astronomical Society, the team modeled the formation of galaxies in the universe’s first few hundred million years. When they incorporated a dark energy component only in that earliest sliver of time, they found the number of galaxies that arose from the primordial environment bloomed to fit astronomers’ observations.
“You have these two looming open-ended puzzles,” says study co-author Rohan Naidu, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “We find that in fact, early dark energy is a very elegant and sparse solution to two of the most pressing problems in cosmology.”
The study’s co-authors include lead author and Kavli postdoc Xuejian (Jacob) Shen, and MIT professor of physics Mark Vogelsberger, along with Michael Boylan-Kolchin at the University of Texas at Austin, and Sandro Tacchella at the University of Cambridge.
Big city lights
Based on standard cosmological and galaxy formation models, the universe should have taken its time spinning up the first galaxies. It would have taken billions of years for primordial gas to coalesce into galaxies as large and bright as the Milky Way.
But in 2023, NASA’s James Webb Space Telescope (JWST) made a startling observation. With an ability to peer farther back in time than any observatory to date, the telescope uncovered a surprising number of bright galaxies as large as the modern Milky Way within the first 500 million years, when the universe was just 3 percent of its current age.
“The bright galaxies that JWST saw would be like seeing a clustering of lights around big cities, whereas theory predicts something like the light around more rural settings like Yellowstone National Park,” Shen says. “And we don’t expect that clustering of light so early on.”
For physicists, the observations imply that there is either something fundamentally wrong with the physics underlying the models or a missing ingredient in the early universe that scientists have not accounted for. The MIT team explored the possibility of the latter, and whether the missing ingredient might be early dark energy.
Physicists have proposed that early dark energy is a sort of antigravitational force that is turned on only at very early times. This force would counteract gravity’s inward pull and accelerate the early expansion of the universe, in a way that would resolve the mismatch in measurements. Early dark energy, therefore, is considered the most likely solution to the Hubble tension.
Galaxy skeleton
The MIT team explored whether early dark energy could also be the key to explaining the unexpected population of large, bright galaxies detected by JWST. In their new study, the physicists considered how early dark energy might affect the early structure of the universe that gave rise to the first galaxies. They focused on the formation of dark matter halos — regions of space where gravity happens to be stronger, and where matter begins to accumulate.
“We believe that dark matter halos are the invisible skeleton of the universe,” Shen explains. “Dark matter structures form first, and then galaxies form within these structures. So, we expect the number of bright galaxies should be proportional to the number of big dark matter halos.”
The team developed an empirical framework for early galaxy formation, which predicts the number, luminosity, and size of galaxies that should form in the early universe, given some measures of “cosmological parameters.” Cosmological parameters are the basic ingredients, or mathematical terms, that describe the evolution of the universe.
Physicists have determined that there are at least six main cosmological parameters, one of which is the Hubble constant — a term that describes the universe’s rate of expansion. Other parameters describe density fluctuations in the primordial soup, immediately after the Big Bang, from which dark matter halos eventually form.
The MIT team reasoned that if early dark energy affects the universe’s early expansion rate, in a way that resolves the Hubble tension, then it could affect the balance of the other cosmological parameters, in a way that might increase the number of bright galaxies that appear at early times. To test their theory, they incorporated a model of early dark energy (the same one that happens to resolve the Hubble tension) into an empirical galaxy formation framework to see how the earliest dark matter structures evolve and give rise to the first galaxies.
“What we show is, the skeletal structure of the early universe is altered in a subtle way where the amplitude of fluctuations goes up, and you get bigger halos, and brighter galaxies that are in place at earlier times, more so than in our more vanilla models,” Naidu says. “It means things were more abundant, and more clustered in the early universe.”
“A priori, I would not have expected the abundance of JWST’s early bright galaxies to have anything to do with early dark energy, but their observation that EDE pushes cosmological parameters in a direction that boosts the early-galaxy abundance is interesting,” says Marc Kamionkowski, professor of theoretical physics at Johns Hopkins University, who was not involved with the study. “I think more work will need to be done to establish a link between early galaxies and EDE, but regardless of how things turn out, it’s a clever — and hopefully ultimately fruitful — thing to try.”
“We demonstrated the potential of early dark energy as a unified solution to the two major issues faced by cosmology. This might be an evidence for its existence if the observational findings of JWST get further consolidated,” Vogelsberger concludes. “In the future, we can incorporate this into large cosmological simulations to see what detailed predictions we get.”
This research was supported, in part, by NASA and the National Science Foundation.
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Plant-derived secondary organic aerosols can act as mediators of plant-plant interactions
A new study published in Science reveals that plant-derived secondary organic aerosols (SOAs) can act as mediators of plant-plant interactions. This research was conducted through the cooperation of chemical ecologists, plant ecophysiologists and atmospheric physicists at the University of Eastern Finland.
The study showed that Scots pine seedlings, when damaged by large pine weevils, release VOCs that activate defences in nearby plants of the same species. Interestingly, the biological activity persisted after VOCs were oxidized to form SOAs. The results indicated that the elemental composition and quantity of SOAs likely determines their biological functions.
“A key novelty of the study is the finding that plants adopt subtly different defence strategies when receiving signals as VOCs or as SOAs, yet they exhibit similar degrees of resistance to herbivore feeding,” said Professor James Blande, head of the Environmental Ecology Research Group. This observation opens up the possibility that plants have sophisticated sensing systems that enable them to tailor their defences to information derived from different types of chemical cue.
“Considering the formation rate of SOAs from their precursor VOCs, their longer lifetime compared to VOCs, and the atmospheric air mass transport, we expect that the ecologically effective distance for interactions mediated by SOAs is longer than that for plant interactions mediated by VOCs,” said Professor Annele Virtanen, head of the Aerosol Physics Research Group. This could be interpreted as plants being able to detect cues representing close versus distant threats from herbivores.
The study is expected to open up a whole new complex research area to environmental ecologists and their collaborators, which could lead to new insights on the chemical cues structuring interactions between plants.
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Folded or cut, this lithium-sulfur battery keeps going
Most rechargeable batteries that power portable devices, such as toys, handheld vacuums and e-bikes, use lithium-ion technology. But these batteries can have short lifetimes and may catch fire when damaged. To address stability and safety issues, researchers reporting in ACS Energy Letters have designed a lithium-sulfur (Li-S) battery that features an improved iron sulfide cathode. One prototype remains highly stable over 300 charge-discharge cycles, and another provides power even after being folded or cut.
The team coated iron sulfide cathodes in different polymers and found in initial electrochemical performance tests that polyacrylic acid (PAA) performed best, retaining the electrode’s discharge capacity after 300 charge-discharge cycles. Next, the researchers incorporated a PAA-coated iron sulfide cathode into a prototype battery design, which also included a carbonate-based electrolyte, a lithium metal foil as an ion source, and a graphite-based anode. They produced and then tested both pouch cell and coin cell battery prototypes.
After more than 100 charge-discharge cycles, Wang and colleagues observed no substantial capacity decay in the pouch cell. Additional experiments showed that the pouch cell still worked after being folded and cut in half. The coin cell retained 72% of its capacity after 300 charge-discharge cycles. They next applied the polymer coating to cathodes made from other metals, creating lithium-molybdenum and lithium-vanadium batteries. These cells also had stable capacity over 300 charge-discharge cycles. Overall, the results indicate that coated cathodes could produce not only safer Li-S batteries with long lifespans, but also efficient batteries with other metal sulfides, according to Wang’s team.
The authors acknowledge funding from the National Natural Science Foundation of China; the Natural Science Foundation of Sichuan, China; and the Beijing National Laboratory for Condensed Matter Physics.
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