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Comment by Dr. Krishna Kumari Challa on December 18, 2025 at 8:53am

HOW THE BRAIN MEASURES DISTANCE OF A FAMILIAR PLACE IN THE DARK

Whether you are heading to bed or toilet of your home in the dark, you don't need to turn on the lights to know where you are as you walk through your house at night. This hidden skill comes from a remarkable ability called path integration: your brain constantly tallies your steps and turns, allowing you to mentally track your position like a personal GPS. You're building a map by tracking movement, not sight.
Scientists think that understanding how the brain performs path integration could be a critical step toward understanding how our brain turns momentary experiences into memories of events that unfold over time.
In their study, the team trained mice to run a specific distance in a gray virtual reality environment without visual landmarks, in exchange for a reward. The animals could only judge how far they had traveled by monitoring their own movement, not by relying on environmental cues.

As mice performed this task, the scientists recorded tiny electrical pulses that neurons use to communicate, allowing them to observe the activity of thousands of neurons.

They focused on the activity of neurons in the hippocampus, a region essential for both navigation and memory. Using computer modeling, they then analyzed these signals to reveal the computational rules the brain uses for path integration.
The hippocampus is known to help animals find their way through the environment. In this brain region, some neurons become active at specific places. However, in environments full of sights, sounds, and smells, it is difficult to tell whether these neurons are responding to those sensory cues or to the animal's position itself.
The scientists discovered that during navigation without landmarks, most hippocampal neurons followed one of two opposite patterns of activity. These patterns were crucial for helping the animals keep track of how far they had traveled.

In one group of neurons, activity sharply increased when the animal started moving, as if marking the start of the distance-counting process. The activity of these neurons then gradually ramped down at different rates as the animal moved further, until reaching the set distance for a reward.

A second group of neurons showed the opposite pattern. Their activity dropped when the animal started moving, but gradually ramped up as the animal traveled farther.

The team discovered that these activity patterns act as a neural code for distance, with two distinct phases. The first phase (the rapid change in neural activity) marks the start of movement and the beginning of distance counting. The second phase (the gradual ramping changes in neural activity) counts the distance traveled. Both short and long distances could be tracked in the brain by using neurons with different ramping speeds.
The scientists have discovered that the brain encodes the elapsed distance or time needed to solve this task using neurons that show ramping activity patterns.
This is the first time distance has been shown to be encoded in a way that differs from the well-known place-based coding in the hippocampus. These findings expand our understanding that the hippocampus is using multiple strategies—ramping patterns in addition to the place-based coding—to encode elapsed time and distance."

When the researchers disrupted these patterns by manipulating the circuits that produce them, the animals had difficulty performing the task accurately and often searched for the reward in the wrong location.

Time or distance encoding by hippocampal neurons via heterogeneous ramping rates, Nature Communications (2025). DOI: 10.1038/s41467-025-67038-3

Comment by Dr. Krishna Kumari Challa on December 18, 2025 at 8:36am

Grok spews misinformation about deadly Australia shooting
Grok, an AI chatbot, disseminated multiple false claims during the Bondi Beach mass shooting in Australia, including misidentifying a hero, mislabeling images, and suggesting a survivor staged his injuries. These errors highlight the limitations of AI chatbots in real-time fact-checking, especially during rapidly evolving news events, and underscore the continued need for human oversight.

Source: News agencies

Comment by Dr. Krishna Kumari Challa on December 18, 2025 at 8:09am

The team also has a theory as to how WHG genes may help people live to a ripe old age. They suggest that these variants were selected during the last Ice Age, when our ancestors had to survive extremely harsh conditions with limited food resources. The scientists think these genes helped improve metabolism to process food more efficiently and strengthen the immune system to protect the body from age-related stresses.

Stefania Sarno et al, Western Hunter-Gatherer genetic ancestry contributes to human longevity in the Italian population, GeroScience (2025). DOI: 10.1007/s11357-025-02043-4

Part 2

Comment by Dr. Krishna Kumari Challa on December 18, 2025 at 8:08am

Why some people live to 100 years or more? Because they carry a higher proportion of genetic material from Western Hunter-Gatherers!

Our hunter-gatherer ancestors have given us many things. They passed down mastery of fire for cooking and early survival technologies, such as stone tools. They may also have given us the secret to a long life. A new study published in the journal GeroScience found that Italian centenarians carry a higher proportion of genetic material from Western Hunter-Gatherers (WHG) compared to the general population.

It has been known for some time that longevity can be explained by "good" genes, as well as by other factors such as our environment and daily habits. Some studies have found individual genes linked to longer life, while others suggest that ancestral DNA may play a role.

Italy has one of the highest concentrations in the world of people living to 100 or more. To help understand why, researchers analyzed the genomes of 333 centenarians and 690 healthy adult controls aged around 50. They compared the DNA of these individuals with 103 ancient genomes of the four groups that make up the modern Italian gene pool.

These are Western Hunter-Gatherers, who were among the original inhabitants of Europe after the Ice Age, Anatolian Neolithic farmers, Bronze Age nomadic groups and ancient groups from the Iranian and Caucasus regions.
The results revealed that those who reached the age of 100 tended to have more Western Hunter-Gatherer DNA than the average person. "The present study shows for the first time that the Villabruna cluster/WHG lineage... contributes to longevity in the Italian population," wrote the research team.

Till now mediterranean diet stole most of the credit!

While everyone in the study carried a mix of DNA from all four ancient groups, only the WHG genetic material was linked to longevity.

In fact, for every small increase in hunter-gatherer DNA, a person's odds of becoming a centenarian rose by 38%. This was even more powerful in women, who were more than twice as likely to reach 100 if they had a higher proportion of this ancient DNA. 
Part 1

Comment by Dr. Krishna Kumari Challa on December 17, 2025 at 9:50am

Study finds sports injuries sustained during a woman's period might be more severe
Injuries sustained by elite female football players during menstruation are more severe and result in over three times more days lost compared to injuries at other times in the menstrual cycle. While menstruation does not increase injury incidence, hormonal and physiological changes may worsen injury severity and prolong recovery. Individual menstrual tracking and tailored training may help reduce injury impact.

Menstruation and injury occurrence; a four season observational study in elite female football players, Frontiers in Sports and Active Living (2025). DOI: 10.3389/fspor.2025.1665482

Comment by Dr. Krishna Kumari Challa on December 17, 2025 at 9:47am

Biodegradable dishes could transfer gluten to foods, posing health risk to gluten-sensitive individuals
Some biodegradable tableware made from wheat by-products can contain gluten and transfer it to foods and drinks at levels exceeding gluten-free regulatory thresholds, particularly into liquids. This poses a potential health risk for individuals with celiac disease or gluten sensitivity, as such products are not required to carry allergen labels.

In 30-minute experiments conducted by researchers, gluten-free foods were placed on the different tableware items at room temperature. The foods' gluten contents were measured and compared against the gluten-free (less than 20 ppm) and low-gluten (less than 100 ppm) regulatory thresholds set by the European Union and the U.S. Food and Drug Administration. Only the gluten-containing plate passed protein into omelet, rice, milk and vegetable cream samples. Significantly less gluten transferred into the solid foods than into the liquids:

• Rice: up to 17 ppm, below the gluten-free threshold.
• Omelet: up to 30 ppm, below the low-gluten threshold.
• Milk: up to 240 ppm, over the low-gluten threshold.
• Vegetable cream: up to 2,100 ppm, over the low-gluten threshold.

In some cases, microwaving foods in the dish reduced gluten contamination compared to room temperature samples, and the researchers hypothesize it is because heat denatures the protein and disrupts its transfer into foods.

The researchers urge mandatory gluten labeling for materials that contact food.

Carolina Sousa et al, Potential Transfer of Toxic Gluten from Biodegradable Tableware to Gluten-Free Foods: Implications for Individuals with Gluten-Related Disorders, Journal of Agricultural and Food Chemistry (2025). DOI: 10.1021/acs.jafc.5c07516

Comment by Dr. Krishna Kumari Challa on December 17, 2025 at 9:24am

40% of MRI signals do not correspond to actual brain activity, study suggests
Approximately 40% of fMRI signals do not accurately reflect neuronal activity, as increased signals can correspond to reduced brain activity and vice versa. Oxygen consumption in active brain regions often rises without increased blood flow, indicating more efficient oxygen extraction rather than greater perfusion. These findings challenge standard interpretations of fMRI data, especially in studies of brain disorders.

For almost three decades, functional magnetic resonance imaging (fMRI) has been one of the main tools in brain research. Yet a new study published in Nature Neuroscience fundamentally challenges the way fMRI data have so far been interpreted with regard to neuronal activity.

According to the findings, there is no generally valid coupling between the oxygen content measured by MRI and neuronal activity.

Researchers found that an increased fMRI signal is associated with reduced brain activity in around 40% of cases. At the same time, they observed decreased fMRI signals in regions with elevated activity.

This contradicts the long-standing assumption that increased brain activity is always accompanied by an increased blood flow to meet higher oxygen demand. Since tens of thousands of fMRI studies worldwide are based on this assumption, these new results could lead to opposite interpretations in many of them.

According to the researchers, these insights also affect the interpretation of research findings in brain disorders. Many fMRI studies on psychiatric or neurological diseases—from depression to Alzheimer's—interpret changes in blood flow as a reliable signal of neuronal under- or over-activation.

Given the limited validity of such measurements, this must now be reassessed. Especially in patient groups with vascular changes—for instance, due to aging or vascular disease—the measured values may primarily reflect vascular differences rather than neuronal deficits, say the researchers.

The researchers therefore propose complementing the conventional MRI approach with quantitative measurements. In the long term, this combination could form the basis for energy-based brain models: rather than showing activation maps that depend on assumptions about blood flow, future analyses could display values indicating how much oxygen—and therefore energy—is actually consumed for information processing.

Samira M. Epp et al, BOLD signal changes can oppose oxygen metabolism across the human cortex, Nature Neuroscience (2025). DOI: 10.1038/s41593-025-02132-9

Comment by Dr. Krishna Kumari Challa on December 17, 2025 at 9:18am

A mild brain injury can trigger Alzheimer's

Mild traumatic brain injury disrupts brain lymphatic vessel function, impairing waste clearance and accelerating harmful tau protein accumulation associated with Alzheimer's disease. Early intervention to restore lymphatic drainage in laboratory models prevented tau buildup and brain degeneration, suggesting a potential therapeutic strategy to reduce Alzheimer's and other neurodegenerative risks after head trauma.

Ana Royo Marco et al, Therapeutic VEGFC treatment provides protection against traumatic-brain-injury-driven tauopathy pathogenesis, Cell Reports (2025). DOI: 10.1016/j.celrep.2025.116521

Comment by Dr. Krishna Kumari Challa on December 17, 2025 at 9:12am

Emerging science: The positive health benefits of microbes

Viruses and bacteria get a bad rap around the world, but now  experts are identifying the positive "upside" of powerful benefits that microbes have on human health.

They  presented a timely reminder of these 'invisible friends' in a new article published in Microbial Biotechnology, underlining the benefits of moving away from a threat-centered view of microbes and biogenic compounds.

The article introduces the "Database of Salutogenic Potential," a world-first prototype open-access repository that catalogs microbes and natural compounds linked to positive health outcomes.

Emerging evidence shows that exposure to diverse environmental microbiomes and natural biochemical products also promotes health and resilience. Rather than viewing biodiversity as something to be eliminated, contemporary approaches recognize the vital role of diverse ecosystems in creating salutogenic, or health-promoting, environments.

By consolidating this data, researchers aim to rebalance the story of microbes—highlighting not only what makes us sick, but also what keeps us well. After all, health is not merely the absence of disease. The implications are far-reaching—from designing healthier cities and schoolyards to guiding ecosystem restoration and rethinking green infrastructure.

Salutogenic microbes—those that promote health—and beneficial biochemical compounds have received comparatively little attention despite their important roles in regulating immune function and metabolic processes, suppressing disease, mitigating stress and supporting ecosystem resilience.

For well over a century,  microbes in the air have mainly been studied as threats—causes of infection, disease and contamination. While this pathogen-centric lens has saved countless lives, it also risks overlooking the invisible biodiversity that actively supports human and planetary health. Just as biodiversity loss threatens our health, restoring microbial and biochemical richness could be a key to healthier futures.

The researchers have identified 124 potentially salutogenic microbial taxa and 14 biochemical compounds (from soil bacteria to plant-derived phytoncides) associated with benefits ranging from immune regulation to stress reduction.

Jake M. Robinson et al, Mapping and Cataloguing Microbial and Biochemical Determinants of Health: Towards a 'Database of Salutogenic Potential', Microbial Biotechnology (2025). DOI: 10.1111/1751-7915.70243

Comment by Dr. Krishna Kumari Challa on December 17, 2025 at 8:37am

Living rocks in South Africa rapidly absorb carbon

South Africa is home to some of the oldest evidence of life on Earth, contained in rocky, often layered outcroppings called microbialites. Like coral reefs, these complex "living rocks" are built up by microbes absorbing and precipitating dissolved minerals into solid formations.

A new study suggests that these microbialites aren't just surviving—they're thriving.

A paper  published in Nature Communications, quantifies how microbialites along the South African coast take up carbon and turn it into fresh layers of calcium carbonate. They show how these structures utilize photosynthesis and chemical processes to absorb carbon day and night, relating those rates for the first time to the genetic makeup of the microbial community.

The findings highlight just how efficient these microbial mats are at removing dissolved carbon from their environment and sequestering it into stable mineral deposits.

Researchers found that these systems were precipitating calcium carbonate rapidly, estimating that the structures can grow almost two inches vertically every year.

More surprising was the finding of carbon uptake day and night. These systems have long been assumed to be driven solely by photosynthesis.

After repeating their experiments several times, the researchers confirmed that the microbes are utilizing metabolic processes other than photosynthesis to absorb carbon in the absence of light, similar to how microbes living in deep-sea vents survive.

Based on daily rates of carbon uptake, the team estimates that these microbialites can absorb the equivalent of nine to 16 kilograms of carbon dioxide every year per square meter.

Rachel E. Sipler et al, Integration of multiple metabolic pathways supports high rates of carbon precipitation in living microbialites, Nature Communications (2025). DOI: 10.1038/s41467-025-66552-8

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