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Comment by Dr. Krishna Kumari Challa on March 13, 2025 at 7:24am

When somebody says 'shut up!', how do you stop speaking?

A premotor cortical network in the brain allows people to voluntarily stop speaking, study suggests

Speech is a unique human ability that is known to be supported by various motor and cognitive processes. When humans start speaking, they can decide to cease at any point; for instance, if they are interrupted by something happening or by another person speaking to them.

The ability to voluntarily stop speaking plays a central role in social interactions, as it allows people to engage in conversations with others while adaptively responding to social cues, environmental stimuli or interruptions.

Researchers  recently set out to better understand how the human brain controls the ceasing of speech using tools to record neurophysiological signals. Their paper, published in Nature Human Behaviour, unveils a previously unknown premotor cortical network that could support voluntary speech inhibition.

Researchers recruited 13 patients diagnosed with treatment-resistant epilepsy who had electrodes implanted on their brains' surfaces to better understand the brain regions that contribute to their epileptic seizures. These patients were asked to complete a speech-stopping task, which asked them to follow instructions on when to start and stop speaking, while their neural activity was recorded.

Neural recordings revealed distinct activity in the premotor frontal cortex correlated with stopping speech. This activity was found in largely separate cortical sites from regions encoding vocal tract articulatory movements. Moreover, this activity primarily occurred with abrupt stopping in the middle of an utterance, rather than naturally completing a phrase.

The findings gathered by this team of researchers hint at the existence of a specialized brain mechanism that supports the voluntary control of speech.

The researchers conducted further tests aimed at validating the existence of this mechanism by stimulating specific parts of the premotor frontal cortex.

Electrocortical stimulation at many premotor sites with inhibitory stop activity caused involuntary speech arrest, which contradicts previous clinical interpretations of this effect as evidence for critical centers of speech production," wrote the team in their paper. "Together, these results suggest a previously unknown premotor cortical network that supports the inhibitory control of speech, providing implications for understanding both natural and altered speech production."

Overall, the results of this study suggest that the human ability to voluntarily stop speech is supported by a particular inhibitory control neural network that had not been uncovered before.

Lingyun Zhao et al, Inhibitory control of speech production in the human premotor frontal cortex, Nature Human Behaviour (2025). DOI: 10.1038/s41562-025-02118-4

Comment by Dr. Krishna Kumari Challa on March 12, 2025 at 11:37am

Turtle Dance
Researchers found that the turtles exhibited significantly higher levels of ‘turtle dance’ behaviour when they were in their designated feeding fields, strongly suggesting that they could distinguish between the two magnetic fields.

Comment by Dr. Krishna Kumari Challa on March 12, 2025 at 11:24am

A 'Yellow Brick Road' at The Bottom of The Pacific Ocean

An example of ancient active volcanic geology!

Comment by Dr. Krishna Kumari Challa on March 12, 2025 at 10:58am

Coma brain waves hint at who’s waking up

A pattern of brain waves that occurs during sleep might help to predict whether an unresponsive person who experienced severe brain.... Researchers recorded the electrical activity in the brains of 226 people in a coma who had experienced recent brain injury, and homed in on a specific patterns of brain activity called sleep spindles. They found that 28% of people who had well-defined sleep spindles recovered consciousness, compared with only 14% of those who lacked this pattern. “We're starting to lift the lid a little bit and find some signs of recovery as it's happening,” says neurologist and study co-author Jan Claassen.

ScienceAlert
Reference: Nature Medicine paper

Comment by Dr. Krishna Kumari Challa on March 12, 2025 at 10:32am

bioRxiv and medRxiv make it official

A new chapter has begun for two of the world’s most popular preprint platforms, bioRxiv and medRxiv, with the launch of a non-profit organization that will manage them. openRxiv, which will have a board of directors and a scientific and medical advisory board, takes over from Cold Spring Harbor Laboratory in New York. It has “become so important that they should have their own organization running them, which is focused on the long-term sustainability of the servers, as opposed to being a side project within a big research institution,” says Richard Sever, the co-founder of both servers.

Nature | 

Preprint sites bioRxiv and medRxiv launch new era of independence

The popular repositories, where life scientists post research before peer review, will be managed by a new organization called openRxiv.

https://www.nature.com/articles/d41586-025-00762-4?utm_source=Live+...

Comment by Dr. Krishna Kumari Challa on March 12, 2025 at 9:37am

Microplastics may threaten global food supply by disrupting photosynthesis

A team of environmental researchers, Earth scientists and pollution specialists  has found evidence that microplastics have a negative impact on photosynthesis in terrestrial, marine, and freshwater ecosystems.

In their study, published in the Proceedings of the National Academy of Sciences, the group conducted a meta-analysis of data from more than 150 studies involving the impact of microplastics on plants.

Prior research has shown that microplastics have made their way to nearly every ecosystem on the planet, and now contaminate plants and animals, including humans. For this new study, the research team wondered if microplastics might have an unknown impact on plants living in the ocean, in fresh water or growing on land, and they conducted a study of prior research to find out.

The team suspected that microplastics might have a direct impact on the ability of plants to engage in photosynthesis. To that end, they searched the literature using an AI app and found 157 studies that mentioned both microplastics and impacts on photosynthesis, which included 3,286 observations.

Combining the results, the researchers calculated that microplastics reduced photosynthetic efficiency across all three plant types by 7% to 12% and caused reductions in production of chlorophyll. Such percentages, they suggest, result in approximately 4% to 14% harvest yield losses of maize, wheat and rice around the globe. They also suggest that microplastics account for up to 7% of losses in global aquatic net primary productivity.

The research team notes that the problem appears to be worsening, which will impact crop production even more. They further suggest that if the problem is not reversed, the result could be a major increase in the number of people at risk of starvation over the next two decades.

 Ruijie Zhu et al, A global estimate of multiecosystem photosynthesis losses under microplastic pollution, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2423957122

Comment by Dr. Krishna Kumari Challa on March 12, 2025 at 9:28am

The same principle applies beyond neuroscience. Imagine a landscape where temperatures and rainfall vary gradually over a space. You might expect species to be spread, and also to vary, smoothly over this region. But in reality, ecosystems often form species clusters with sharp boundaries—distinct ecological "neighborhoods" that don't overlap.

The new study suggests why local competition, cooperation, and predation between species interact with the global environmental gradients to create natural separations, even when the underlying conditions change gradually. This phenomenon can be explained using peak selection and suggests that the same principle that shapes brain circuits could also be at play in forests and oceans.

One of the researchers' most striking findings is that modularity in these systems is remarkably robust. Change the size of the system, and the number of modules stays the same—they just scale up or down. That means a mouse brain and a human brain could use the same fundamental rules to form their navigation circuits, just at different sizes.

The model also makes testable predictions. If it's correct, grid cell modules should follow simple spacing ratios. In ecosystems, species distributions should form distinct clusters even without sharp environmental shifts.

The work adds another conceptual framework to biology. "Peak selection can inform future experiments, not only in grid cell research but across developmental biology.

Mikail Khona et al, Global modules robustly emerge from local interactions and smooth gradients, Nature (2025). DOI: 10.1038/s41586-024-08541-3

Part 3

Comment by Dr. Krishna Kumari Challa on March 12, 2025 at 9:26am

The authors of the research paper propose a simple mathematical principle called peak selection, showing that when a smooth gradient is paired with local interactions that are competitive, modular structures emerge naturally. In this way, biological systems can organize themselves into sharp modules without detailed top-down instruction.

The researchers tested their idea on grid cells, which play a critical role in spatial navigation as well as the storage of episodic memories. Grid cells fire in a repeating triangular pattern as animals move through space, but they don't all work at the same scale—they are organized into distinct modules, each responsible for mapping space at slightly different resolutions.

No one knows how these modules form, but the new model shows that gradual variations in cellular properties along one dimension in the brain, combined with local neural interactions, could explain the entire structure. The grid cells naturally sort themselves into distinct groups with clear boundaries, without external maps or genetic programs telling them where to go.

The new  work explains how grid cell modules could emerge. The explanation tips the balance toward the possibility of self-organization. It predicts that there might be no gene or intrinsic cell property that jumps when the grid cell scale jumps to another module.

Part 2

Comment by Dr. Krishna Kumari Challa on March 12, 2025 at 9:22am

How nature organizes itself, from brain cells to ecosystems

You'll see it everywhere: the way trees form branches, the way cities divide into neighborhoods, the way the brain organizes into regions. Nature loves modularity—a limited number of self-contained units that combine in different ways to perform many functions. But how does this organization arise?

In findings published in Nature, researchers report that a mathematical model called peak selection can explain how modules emerge without strict genetic instructions. The findings, which apply to brain systems and ecosystems, help explain how modularity occurs across nature, no matter the scale.

Scientists have debated how modular structures form. One hypothesis suggests that various genes are turned on at different locations to begin or end a structure. This explains how insect embryos develop body segments, with genes turning on or off at specific concentrations of a smooth chemical gradient in the insect egg.

Another idea, inspired by mathematician Alan Turing, suggests that a structure could emerge from competition—small-scale interactions can create repeating patterns, like the spots on a cheetah or the ripples in sand dunes.

Both ideas work well in some cases, but fail in others. The new research suggests that nature need not pick one approach over the other.

Part 1

Comment by Dr. Krishna Kumari Challa on March 12, 2025 at 9:14am

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