The study found that a rapid thalamic signal is present during waking and dreaming states but disappears during non-REM sleep, highlighting its potential role in consciousness.
Category: biological
The delusion of a particle-only universe
If everything that happens in the world ultimately comes down to the behavior of fundamental particles, it would seem that other entities, from cells to human beings, from currencies to financial markets, aren’t really causing anything at all—that they are just shadows cast by patterns at the most fundamental level. But philosopher David Yates argues this conclusion is wrong. The whole affects the parts, and higher-level structures don’t just describe what is happening at lower levels in more convenient terms—they actively shape what is possible. This means that chemists, biologists, psychologists, and economists aren’t chasing shadows. They are studying structures that genuinely shape how the world unfolds.
In 1974, Jerry Fodor published a seminal paper titled ‘Special Sciences’, in which he argued for an intuitive and compelling picture of the relationship between fundamental physics and higher-level sciences such as biology, psychology and economics. Our world, according to Fodor, is arranged hierarchically, with fundamental physical particles at the bottom, combining to form molecules, which combine to form cells, which combine to form complex organisms, some of which have mental states, among them humans, who combine to form complex societies. The sciences are likewise arranged, with physics at the bottom, followed by chemistry, biology, physiology, neuroscience, psychology, sociology and economics. Now it is vanishingly unlikely, says Fodor, that things that share e.g. psychological or economic properties, also share some property specifiable in the language of physics or other lower-level sciences.
Laser beam builds cell-like protein networks without chemical modification
Networks of protein fibers play important roles in living cells. To understand the dynamical behavior of these networks, model networks are needed to perform in vitro studies. However, fabrication of protein networks similar to those in cells has proved difficult, as current methods could affect the biological function of these proteins—ultimately impacting our understanding of any findings.
Now, researchers at The University of Osaka and Saitama University have used a laser beam to precisely fabricate a network of protein fibers. Their discovery was recently reported in Advanced Science.
The shape of living cells is determined by an internal network of protein fibers called a cytoskeleton. The cytoskeletal structure is dynamic, as the key nodes for cell function shift over time. One such cell function can be witnessed with motor proteins, which convert chemical energy into mechanical work. These proteins walk along cytoskeletal tracks to drive muscle contraction and transport components across the cell.
New X-ray method captures solid-liquid interfaces and bulk liquids simultaneously
Researchers have developed a method for making simultaneous soft X-ray absorption spectroscopy (XAS) measurements of solid-liquid interfaces and bulk liquids. By controlling the thickness of the liquid layer, they obtained the O K-edge XAS spectrum of bulk H2O from a liquid H2O layer on a thin Au film using the transmission method, and they used the electron-yield method to obtain the XAS spectrum of the H2O/Au interface by measuring the drain currents from the Au surface following soft X-ray absorption. This method for obtaining simultaneous XAS measurements of solid-liquid interfaces and bulk liquids can be utilized to investigate the mechanisms of a variety of catalytic, electrochemical, and biological reactions involving solid-liquid interfaces.
Water molecules at solid-liquid interfaces play important roles in various catalytic, electrochemical, and biological reactions. Soft X-ray absorption spectroscopy (XAS) is an element-specific method for investigating the electronic structures of liquid water and organic molecules. In this study, the researchers developed a method for simultaneously obtaining XAS measurements of a solid-liquid interface, using the electron-yield method, and of the bulk liquid, using the transmission method. The paper is published in the Journal of Synchrotron Radiation.
In the present work, they measured the XAS spectra while precisely controlling the thickness of the liquid layer in the range from 20 nm to 40 μm in a liquid cell for the transmission of soft X-rays. The XAS spectra acquired in transmission mode are derived mainly from the bulk liquid because the contributions from the solid-liquid interfaces are smaller than those from the bulk liquid. In contrast, the XAS spectra of solid-liquid interfaces are obtained by detecting Auger electrons, which originate mostly from those interfaces because they escape only from shallow depths.
Why Nanoscale Droplets Don’t Coalesce
A well-shaken mixture of oil and vinegar will separate as the oil droplets eventually coalesce. Droplet growth, or coarsening, usually evolves according to standard rules. But puzzling exceptions persist. When two polymers are mixed in water and the concentration is high enough, droplets containing one or both species form and can remain stable for hours or days. These loose molecular condensates otherwise behave like liquid droplets, and they abound in biological cells. Now Feipeng Chen of the University of Hong Kong and his colleagues have developed a predictive model for coarsening behavior that works across a range of droplet sizes and explains why coarsening may be suppressed in living systems [1].
The researchers derived their model from observations of a solution containing water and two different polymers, opposite in charge and having very different molecular chain lengths. Using light-scattering techniques, the researchers monitored condensate growth over 12 hours. The initial size and subsequent growth rate of the liquid-like droplets, rich in both polymers, turned out to depend on the solution’s overall initial concentration. In the most dilute solutions, condensates tens-of-nanometers in diameter formed and promptly stopped growing for the remaining 12-hour observation period. In solutions having slightly higher concentration, hundreds-of-nanometer condensates formed and remained stable, then underwent abrupt, rapid growth in the later stages. And in the most concentrated solutions, micrometer-scale condensates formed and grew according to a power-law model.
Applying an electric field to the solutions indicated that the nanoscale condensates had significant surface charge. Modeling these measurements revealed that the asymmetric chain lengths of oppositely charged polymers imparted a net charge to the droplet surfaces. These charges led to size-dependent electrostatic barriers that drastically reduced merging efficiency below a critical diameter. The finding offers a principle for controlling size stability in biology, nanotechnology, and soft-matter assembly.
Scientists identify a cell type in the brain that was previously ignored and it may explain why human memory has no known upper limit
The human brain contains roughly 86 billion neurons. That number appears in almost every popular account of memory and intelligence, and it tends to carry an implicit argument: that the scale of human cognition follows from the scale of this cell count. What is less often mentioned is that the brain contains a roughly comparable number of a different cell type entirely, one that researchers have treated, for most of the history of neuroscience, as little more than biological scaffolding.
A paper published on 23 May in the Proceedings of the National Academy of Sciences puts forward a new hypothesis about what those cells, called astrocytes, might actually be doing. The work comes from a team at MIT: lead author Leo Kozachkov, Jean-Jacques Slotine, a professor of mechanical engineering and brain and cognitive sciences, and Dmitry Krotov of the MIT-IBM Watson AI Lab, who is the paper’s senior author. Their claim is not that astrocytes have been misunderstood in any dramatic sense; it is the more careful suggestion that they may be doing computational work that neurons, on their own, cannot account for.
This is a hypothesis supported by a mathematical model. The experimental work needed to test it has not yet been done.
Zoltan Istvan: The Transhumanist Wager Is A Choice We’ll All Have To Make
Thirteen years ago, I sat down with a writer who had just published his first novel.
It was Zoltan Istvan’s very first media interview as a book author.
The book was The Transhumanist Wager. The question behind it was simple and almost unbearable: what would you do, and what would you give up, to live forever?
I loved half of it. I argued with the other half. That tension is exactly why I think it still matters.
Zoltan built his story out of Plato and Nietzsche, out of Thomas More’s Utopia and Zen Buddhism, then wrapped it all in an Atlas Shrugged plot of lone heroes and evil states. The philosophy is sophisticated. The framing is stark. The contradictions are not a flaw. They are the point.
One line from our conversation has stayed with me for more than a decade:
A new origin story for multicellular life points to physics, not genes alone
How did life make the leap from single cells to coordinated, multicellular organisms? And how do genetically identical cells still perform a version of that feat every time an embryo begins to take shape?
In a new Perspective paper appearing in the journal Nature Biotechnology, Bren Professor of Biology and Biological Engineering Magdalena Zernicka-Goetz and collaborator Qi Chen of the University of Utah ask one of biology’s oldest questions in a new way. The paper is titled “Decoding the origins of cellular self-organization for engineered biology.”
Smaller nanoplastics trigger stronger changes in brain neuron activity
Smaller plastic particles have more effects on neurons, the key information processing cells of the brain, new research from the University of Eastern Finland shows. In the study, neuronal cells were exposed to polystyrene nanoplastics at low doses to study subtle changes.
Plastic production continues to rise, despite worldwide concerns. In addition to environmental implications, there is an increasing interest in how exposure to plastics may impact human health, but our understanding is still limited. Only recently it was shown that plastics can accumulate also in the human brain.
Plastic particles smaller than 5,000 nm in diameter are called microplastics, and the smallest plastic particles with a diameter of less than 1,000 nm are called nanoplastics. The small size of nanoplastics enables them to interact with various cell types, and other particles or biological mass, such as bacteria. Compared to microplastics, nanoplastics have larger adsorption capacity and penetrate through biological barriers more easily. This makes them potentially more harmful and a compelling target for research in the field of neurobiology.