How Does the Brain Make Decisions?

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Scientific Frontline: Extended "At a Glance" Summary: Neural Circuitry of Decision-Making

The Core Concept: The brain finalizes decisions through a structural process where selecting one option actively suppresses the neural pathways associated with alternative options. This mechanism involves specific sequences of neuronal activation that lock in a choice and prevent a change of mind.

Key Distinction/Mechanism: During navigational decision-making, a specific set of excitatory neurons associated with a chosen action (e.g., turning right) fires and subsequently activates a targeted set of inhibitory neurons. These inhibitory cells then curb the activity of the neurons associated with the opposite action (e.g., turning left). This functional architecture within the posterior parietal cortex serves to stabilize the committed decision.

Major Frameworks/Components:

• Connectomics: The comprehensive structural mapping of the wiring and connections between neurons using powerful microscopy.
• Functional Behavioral Analysis: The use of virtual reality mazes to record real-time neuronal activity and decision-making dynamics in active subjects.
• Posterior Parietal Cortex: The specific brain region studied, functioning as an "integrative hub" that receives and processes multisensory information to guide navigational choices.
• Synaptic Wiring Motifs: The specific, rule-based interactions between excitatory and inhibitory neurons that provide the foundation for the brain’s computational processes.

Possible trigger for autoimmune diseases discovered

 One of the great mysteries of immunology: the function of B cells (green) in the thymus gland was previously unknown. Researchers have now been able to show that the immune cells help to prevent T cells from attacking the body.
Image Credit: Jan Böttcher, Thomas Korn / TUM

Immune cells must learn not to attack the body itself. A team of researchers from the Technical University of Munich (TUM) and the Ludwig Maximilian University of Munich (LMU) has discovered a previously unknown mechanism behind this: other immune cells, the B cells, contribute to the "training" of the T cells in the thymus gland. If this process fails, autoimmune diseases can develop.

In children and adolescents, the thymus gland functions as a "school for T cells". The organ in our chest is where the precursors of those T cells that would later attack the body's own cells are discarded. Epithelial cells in the thymus present a large number of molecules that occur in the body to the future T cells. If any of them reacts to one of these molecules, a self-destruction program is triggered. T cells that attack the body's own molecules remaining intact and multiplying, on the other hand, can cause autoimmune diseases.

New mechanism discovered

In Nature, the team led by Thomas Korn, Professor of Experimental Neuroimmunology at TUM and a Principal Investigator in the SyNergy Cluster of Excellence, and Ludger Klein, Professor of Immunology at LMU’s Biomedical Center (BMC), describe another previously unknown mechanism behind this.

In addition to the precursors of T cells, the thymus gland also contains other immune cells, the B cells. They develop in the bone marrow but migrate to the thymus in early childhood. "The function of B cells in the thymus gland has been a mystery that has puzzled immunologists for many years," says Thomas Korn. The researchers have now been able to show for the first time that B cells play an active role in teaching T cells which targets not to attack.

Electrons become fractions of themselves in graphene

The fractional quantum Hall effect has generally been seen under very high magnetic fields, but MIT physicists have now observed it in simple graphene. In a five-layer graphene/hexagonal boron nitride (hBN) moire superlattice, electrons (blue ball) interact with each other strongly and behave as if they are broken into fractional charges.
Image Credit: Sampson Wilcox, RLE
(CC BY-NC-ND 4.0 DEED)

The electron is the basic unit of electricity, as it carries a single negative charge. This is what we’re taught in high school physics, and it is overwhelmingly the case in most materials in nature.

But in very special states of matter, electrons can splinter into fractions of their whole. This phenomenon, known as “fractional charge,” is exceedingly rare, and if it can be corralled and controlled, the exotic electronic state could help to build resilient, fault-tolerant quantum computers.

To date, this effect, known to physicists as the “fractional quantum Hall effect,” has been observed a handful of times, and mostly under very high, carefully maintained magnetic fields. Only recently have scientists seen the effect in a material that did not require such powerful magnetic manipulation.

Now, MIT physicists have observed the elusive fractional charge effect, this time in a simpler material: five layers of graphene — an atom-thin layer of carbon that stems from graphite and common pencil lead. They report their results today in Nature.

They found that when five sheets of graphene are stacked like steps on a staircase, the resulting structure inherently provides just the right conditions for electrons to pass through as fractions of their total charge, with no need for any external magnetic field.

The results are the first evidence of the “fractional quantum anomalous Hall effect” (the term “anomalous” refers to the absence of a magnetic field) in crystalline graphene, a material that physicists did not expect to exhibit this effect.

“This five-layer graphene is a material system where many good surprises happen,” says study author Long Ju, assistant professor of physics at MIT. “Fractional charge is just so exotic, and now we can realize this effect with a much simpler system and without a magnetic field. That in itself is important for fundamental physics. And it could enable the possibility for a type of quantum computing that is more robust against perturbation.”

Black hole fashions stellar beads on a string

The international team used a combination of X-ray, radio, and optical data to understand how this unusual chain of star clusters formed stellar jewellery 3.8 billion light-years from Earth.
Image Credit: X-ray: NASA/CXC/SAO/O. Omoruyi et al.; Optical: NASA/ESA/STScI/G. Tremblay et al.; Radio: ASTRON/LOFAR; Image Processing: NASA/CXC/SAO/N. Wolk

One of the most powerful eruptions from a black hole ever recorded has been discovered by an international team of astronomers.

The mega-explosion, which took place billions of years ago, may help explain the formation of a pattern of star clusters resembling beads on a string, according to the study.

This stellar jewelry is located in SDSS J1531, a massive galaxy cluster 3.8 billion light-years from Earth, containing hundreds of individual galaxies and a huge reservoir of hot gas and dark matter.

At the heart of SDSS J1531, two of the cluster’s largest galaxies are colliding with one another.

These colliding giants are surrounded by a set of 19 large clusters of stars, called superclusters, arranged in an ‘S’ formation that resembles a string of beads.

The team used a combination of X-ray, radio, and optical data to understand how this unusual chain of star clusters formed.

False Alarm of the Immune System during Muscle Disease

Prof. Claudia Günther (left) from Dresden and Prof. Eva Bartok (right) from Bonn are jointly investigating the connection between myotonic dystrophy and autoimmune diseases.
Photo Credit: © Universitätsklinikum Dresden & Universitätsklinikum Bonn

Researchers at the University Hospitals of Dresden and Bonn of the DFG Transregio 237 and from the Cluster of Excellence ImmunoSensation2 at the University of Bonn have made progress clarifying why patients with myotonic dystrophy 2 have a higher tendency to develop autoimmune diseases. Their goal is to understand the development of the disease, and their research has provided new, potential therapeutic targets. The results of the study have now been published in the renowned journal Nature Communications.

Myotonic dystrophy 2 (DM2) is a form of muscular dystrophy, a disease that leads to progressive muscle degeneration. It is caused by the expansion of a repetitive DNA sequence containing multiple CCTG bases in the CNBP gene. In general, the sequence of nucleobases in the DNA carries the genetic information. Patients suffer from muscle weakness that is more pronounced in the area of the muscles close to the trunk, as well as sustained muscle stiffness and pain. Although DM2 occurs in roughly one out of 10,000 people in Germany, there are no targeted therapies. In initial studies, Prof. Claudia Günther and her team at the Carl Gustav Carus University Hospital at the Technical University of Dresden also observed that patients with DM2 suffer more from autoimmune diseases with an increased production of antibodies in the blood than the general population. However, the underlying mechanism for these symptoms was previously unknown.

NIH study offers new clues into the causes of post-infectious ME/CFS

In-depth study finds brain, immune, and metabolic abnormalities linked to debilitating chronic disease.
Image Credit: John A Beal
(CC BY 4.0 DEED)

In a detailed clinical study, researchers at the National Institutes of Health have found differences in the brains and immune systems of people with post-infectious myalgic encephalomyelitis/chronic fatigue syndrome (PI-ME/CFS). They also found distinct differences between men and women with the disease. The findings were published in Nature Communications.

“People with ME/CFS have very real and disabling symptoms, but uncovering their biological basis has been extremely difficult,” said Walter Koroshetz, M.D., director of NIH’s National Institute of Neurological Disorders and Stroke (NINDS). “This in-depth study of a small group of people found a number of factors that likely contribute to their ME/CFS. Now researchers can test whether these findings apply to a larger patient group and move towards identifying treatments that target core drivers of the disease.”

A team of multidisciplinary researchers discovered how feelings of fatigue are processed in the brains of people with ME/CFS. Results from functional magnetic resonance imaging (fMRI) brain scans showed that people with ME/CFS had lower activity in a brain region called the temporal-parietal junction (TPJ), which may cause fatigue by disrupting the way the brain decides how to exert effort.

They also analyzed spinal fluid collected from participants and found abnormally low levels of catecholamines and other molecules that help regulate the nervous system in people with ME/CFS compared to healthy controls. Reduced levels of certain catecholamines were associated with worse motor performance, effort-related behaviors, and cognitive symptoms. These findings, for the first time, suggest a link between specific abnormalities or imbalances in the brain and ME/CFS.

Mitochondrial activation in transplanted cells promotes regenerative therapy for heart healing

Regenerative therapy to treat heart failure is more effective when the mitochondria of the regenerative cells are activated prior to treatment.
Image Credit: Gemini Advance

Heart failure stands as a leading cause of mortality worldwide, demanding advanced treatment options. Despite the urgency for more effective treatments, options for severe heart failure remain limited. Cell transplantation therapy has emerged as a promising ray of hope, as it can be used in regenerative therapy to heal the heart.

A research team led by Professor Yuma Yamada of Hokkaido University’s Faculty of Pharmaceutical Science has developed a technique to promote cardiac regeneration by delivering mitochondrial activators to cardiac progenitor cells. Their findings were published in the Journal of Controlled Release.

“Cardiomyocytes efficiently use the mitochondrial tricarboxylic acid cycle to produce large amounts of adenosine triphosphate from several substrates via oxidative phosphorylation (OXPHOS),” explains Yamada. “Based on the energy metabolism of cardiomyocytes, we hypothesized that activating the mitochondrial function of transplanted cells may improve the outcome of cell transplantation therapy.”

Sleep improves ability to recall complex events

Sleep is important for reinforcing complex associations, the basis for completing memories of entire events
Photo Credit: Shane

Researchers have known for some time that sleep consolidates our memories of facts and episodic events. However, the research to date has concentrated mainly on simple associations – that is to say, connections between elements, such as we make when learning new vocabulary. “But in real life, events are generally made up of numerous components – for example, a place, people, and objects – which are linked together in the brain,” explains Dr. Nicolas Lutz from LMU’s Institute of Medical Psychology. These associations can vary in strength and some elements might be connected with each other only indirectly. “Thanks to the neural connections that underlie these associations, a single cue word is often all it takes for somebody to recall not only individual aspects of an event but multiple aspects at once.” This process, which is known as pattern completion, is a fundamental feature of episodic memory. Lutz is lead author of a study recently published in the journal Proceedings of the National Academy of Sciences (PNAS), which investigated the effect of sleep on memory of such complex events.

Cloud model could help with climate research

Clouds have a number of important functions. They act as reflectors whereby water droplets in the cloud reflect radiation back to the Earth, which contributes to the greenhouse effect.
Photo Credit: Rodion Kutsaiev

When clouds meet clear skies, cloud droplets evaporate as they mix with dry air. A new study involving researchers from the University of Gothenburg has succeeded in capturing what happens in a model. Ultimately, this could lead to more accurate climate modeling in the future.

The clouds in the sky have a significant impact on our climate. Not only do they produce precipitation and provide shade from the sun, they also act as large reflectors that prevent the radiation of heat from the Earth – commonly known as the greenhouse effect.

“Although clouds have been studied for a long time, they are one of the biggest sources of uncertainty in climate models,” explains Bernhard Mehlig, Professor of Complex Systems at the University of Gothenburg. “This is because there are so many factors that determine how the clouds affect radiation. And the turbulence in the atmosphere means that everything is in constant motion. This makes things even more complicated.”

New non-toxic method for producing high-quality graphene oxide

Alexandr Talyzin and his research group at the Department of Physics have developed a new method to synthesize graphene oxide.
Photo Credit: Mattias Pettersson

Researchers from Umeå have found a new way to synthesize graphene oxide which has significantly fewer defects compared to materials produced by the most common method. Similarly good graphene oxide could be synthesized previously only using a rather dangerous method involving extremely toxic fuming nitric acid.

Graphene oxide is often used to produce graphene by removing oxygen. However, if you have holes in graphene oxide, you have holes also after converting it into graphene. Therefore, the quality of the graphene oxide is very important. Alexandr Talyzin and his research group at Umeå University have now cracked the puzzle of how to safely make good graphene oxide. Their results were recently published in the scientific journal Carbon.

Graphene is often described as a “wonder material thanks to its flexibility, high mechanical strength and conductivity. But all properties of graphene are affected by defects. Graphene produced from graphene oxide has much worse than expected mechanical properties and conductivity.