🧠 What If Alzheimer’s Starts Inside Brain Cells — Before the Plaques Take Over?
For decades, Alzheimer’s disease has been strongly associated with amyloid beta plaques — sticky protein deposits that build up between neurons. This idea shaped an entire generation of drug development. But clearing plaques has not been enough to stop or reverse the disease, which suggests the real story may begin earlier and deeper inside the cell.
A new study from the University of California, Riverside, published in PNAS Nexus, proposes a different mechanism: amyloid beta may disrupt neurons by hijacking the same internal “tracks” normally used by tau, another key brain protein.
Inside neurons, microtubules act like tiny railways, helping move vital cargo through long and fragile nerve-cell branches. Tau normally stabilizes these tracks. But the researchers found that amyloid beta can bind to microtubules with roughly similar strength — meaning that, if it accumulates inside neurons, it may compete with tau and push it away from its normal job.
That could trigger a dangerous cascade: microtubules become unstable, cellular transport starts to fail, and displaced tau begins to misbehave — clumping, becoming chemically modified, and moving into parts of the neuron where it does not belong.
In this model, plaques outside cells may not be the original weapon. They may be a visible downstream sign of a much earlier intracellular failure.
Why this matters:
🔹 Amyloid beta and tau appear to compete for overlapping binding sites on microtubules
🔹 The damage may begin inside neurons, before external plaques dominate the picture
🔹 Aging-related decline in autophagy — the cell’s recycling system — could allow amyloid beta to build up internally
🔹 The model may help explain why plaque-clearing drugs have shown limited clinical impact
🔹 It points toward new strategies: protecting microtubules, supporting tau function, or improving intracellular protein cleanup
Important caveat: this is not a clinical trial and not proof that this mechanism causes Alzheimer’s in humans. It is a proposed model based on laboratory experiments — but an interesting one, because it connects two major Alzheimer’s hallmarks, amyloid beta and tau, through the same cellular structure.
More than 57 million people worldwide live with dementia, and Alzheimer’s disease accounts for the majority of cases. If this microtubule-competition model holds up, it could shift part of the field from simply removing plaques to protecting the neuron’s internal transport system before it breaks.
Maybe the real crime scene was never just between brain cells.
Maybe it was inside them all along.
Source: https://doi.org/10.1093/pnasnexus/pgag034
#Alzheimers #Neuroscience #BrainHealth #Dementia #PNASNexus #science
For decades, Alzheimer’s disease has been strongly associated with amyloid beta plaques — sticky protein deposits that build up between neurons. This idea shaped an entire generation of drug development. But clearing plaques has not been enough to stop or reverse the disease, which suggests the real story may begin earlier and deeper inside the cell.
A new study from the University of California, Riverside, published in PNAS Nexus, proposes a different mechanism: amyloid beta may disrupt neurons by hijacking the same internal “tracks” normally used by tau, another key brain protein.
Inside neurons, microtubules act like tiny railways, helping move vital cargo through long and fragile nerve-cell branches. Tau normally stabilizes these tracks. But the researchers found that amyloid beta can bind to microtubules with roughly similar strength — meaning that, if it accumulates inside neurons, it may compete with tau and push it away from its normal job.
That could trigger a dangerous cascade: microtubules become unstable, cellular transport starts to fail, and displaced tau begins to misbehave — clumping, becoming chemically modified, and moving into parts of the neuron where it does not belong.
In this model, plaques outside cells may not be the original weapon. They may be a visible downstream sign of a much earlier intracellular failure.
Why this matters:
🔹 Amyloid beta and tau appear to compete for overlapping binding sites on microtubules
🔹 The damage may begin inside neurons, before external plaques dominate the picture
🔹 Aging-related decline in autophagy — the cell’s recycling system — could allow amyloid beta to build up internally
🔹 The model may help explain why plaque-clearing drugs have shown limited clinical impact
🔹 It points toward new strategies: protecting microtubules, supporting tau function, or improving intracellular protein cleanup
Important caveat: this is not a clinical trial and not proof that this mechanism causes Alzheimer’s in humans. It is a proposed model based on laboratory experiments — but an interesting one, because it connects two major Alzheimer’s hallmarks, amyloid beta and tau, through the same cellular structure.
More than 57 million people worldwide live with dementia, and Alzheimer’s disease accounts for the majority of cases. If this microtubule-competition model holds up, it could shift part of the field from simply removing plaques to protecting the neuron’s internal transport system before it breaks.
Maybe the real crime scene was never just between brain cells.
Maybe it was inside them all along.
Source: https://doi.org/10.1093/pnasnexus/pgag034
#Alzheimers #Neuroscience #BrainHealth #Dementia #PNASNexus #science
Oup
The microtubule nexus linking amyloid beta and tau: A simple and unifying theory for the underlying cause of Alzheimer's disease…
PNAS Nexus, Volume 5, Issue 3, March 2026, pgag034, https://doi.org/10.1093/pnasnexus/pgag034
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🧠 Scientists May Have Found a Missing Link in How Alzheimer’s Kills Brain Cells
For decades, researchers have known that toxic proteins build up in the brains of people with Alzheimer’s disease and other neurodegenerative disorders. But one key question has remained stubbornly difficult:
How exactly does that protein buildup turn into the death of neurons?
A team from King’s College London and the UK Dementia Research Institute has now identified a previously overlooked form of cell death called karyoptosis.
Unlike apoptosis — the well-known “programmed cell death” pathway — karyoptosis appears to attack the cell’s control center first: the nucleus. Under proteotoxic stress, when misfolded proteins accumulate and clump together, the nuclear structure begins to fail. The nucleus shrivels, its supporting scaffold destabilizes, and the cell eventually dies.
The researchers analyzed around 3,000 brain cells from 28 patients with either end-stage Alzheimer’s disease or frontotemporal dementia. In the frontal cortex of Alzheimer’s patients, 35% of cells showed signs of karyoptosis, compared with 15% in healthy older controls.
The key molecular switch appears to involve p38 MAP kinase and LaminB1.
LaminB1 normally helps maintain the structure of the nuclear envelope — the “scaffolding” that keeps the nucleus intact. When toxic proteins accumulate, p38 MAP kinase can destabilize LaminB1, triggering nuclear collapse. In laboratory experiments, blocking this pathway reduced markers of karyoptosis in neurons.
That does not mean scientists have found a cure for Alzheimer’s. This is still early-stage work, and the protective effect has been shown mainly in experimental models, not in living human patients.
But the shift in thinking is important.
Instead of only trying to remove toxic proteins such as amyloid or tau, future therapies might also try to protect neurons from the damage those proteins trigger. In other words: even if the toxic proteins are still there, it may be possible to interrupt the death signal before the cell is lost.
The same mechanism also appears relevant to frontotemporal dementia and ALS models, suggesting karyoptosis may be part of a broader pathway across neurodegenerative disease.
Dementia affects around 57 million people worldwide, and Alzheimer’s disease accounts for roughly 60–70% of cases. Any new route to slowing neuron loss matters — but this one is still a biological roadmap, not a treatment.
The big takeaway:
Sometimes the most important question is not only “what causes the damage?”
It is: what chain reaction does the damage trigger — and can we stop it in time?
Original paper: https://www.nature.com/articles/s41467-026-73802-w
Summary: https://www.sciencedaily.com/releases/2026/06/260626124701.htm
#Alzheimers #Neuroscience #Dementia #BrainHealth #Science
For decades, researchers have known that toxic proteins build up in the brains of people with Alzheimer’s disease and other neurodegenerative disorders. But one key question has remained stubbornly difficult:
How exactly does that protein buildup turn into the death of neurons?
A team from King’s College London and the UK Dementia Research Institute has now identified a previously overlooked form of cell death called karyoptosis.
Unlike apoptosis — the well-known “programmed cell death” pathway — karyoptosis appears to attack the cell’s control center first: the nucleus. Under proteotoxic stress, when misfolded proteins accumulate and clump together, the nuclear structure begins to fail. The nucleus shrivels, its supporting scaffold destabilizes, and the cell eventually dies.
The researchers analyzed around 3,000 brain cells from 28 patients with either end-stage Alzheimer’s disease or frontotemporal dementia. In the frontal cortex of Alzheimer’s patients, 35% of cells showed signs of karyoptosis, compared with 15% in healthy older controls.
The key molecular switch appears to involve p38 MAP kinase and LaminB1.
LaminB1 normally helps maintain the structure of the nuclear envelope — the “scaffolding” that keeps the nucleus intact. When toxic proteins accumulate, p38 MAP kinase can destabilize LaminB1, triggering nuclear collapse. In laboratory experiments, blocking this pathway reduced markers of karyoptosis in neurons.
That does not mean scientists have found a cure for Alzheimer’s. This is still early-stage work, and the protective effect has been shown mainly in experimental models, not in living human patients.
But the shift in thinking is important.
Instead of only trying to remove toxic proteins such as amyloid or tau, future therapies might also try to protect neurons from the damage those proteins trigger. In other words: even if the toxic proteins are still there, it may be possible to interrupt the death signal before the cell is lost.
The same mechanism also appears relevant to frontotemporal dementia and ALS models, suggesting karyoptosis may be part of a broader pathway across neurodegenerative disease.
Dementia affects around 57 million people worldwide, and Alzheimer’s disease accounts for roughly 60–70% of cases. Any new route to slowing neuron loss matters — but this one is still a biological roadmap, not a treatment.
The big takeaway:
Sometimes the most important question is not only “what causes the damage?”
It is: what chain reaction does the damage trigger — and can we stop it in time?
Original paper: https://www.nature.com/articles/s41467-026-73802-w
Summary: https://www.sciencedaily.com/releases/2026/06/260626124701.htm
#Alzheimers #Neuroscience #Dementia #BrainHealth #Science
Nature
Karyoptosis mediates cell death and neurodegeneration upon proteotoxic stress
Nature Communications - This study characterizes karyoptosis as a mechanism of neuronal cell death triggered by proteotoxic stress and executed through disintegration of the nuclear lamina, which...
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🧬 AI Discovers a Natural Peptide That Could Rival Ozempic
Researchers at Stanford Medicine have used artificial intelligence to identify a naturally occurring human peptide that suppresses appetite and promotes weight loss in mice—while avoiding the major side effects commonly associated with GLP-1 drugs like Ozempic.
The newly discovered molecule, called BRP, is only 12 amino acids long. Yet in early laboratory experiments, it activated appetite-regulating neurons far more strongly than existing GLP-1 peptides.
Unlike semaglutide, which acts on receptors throughout the brain, gut, pancreas, and other tissues, BRP appears to target primarily the hypothalamus—the brain region responsible for regulating hunger and metabolism. That more focused mechanism may explain why researchers observed no signs of nausea, constipation, anxiety, or muscle loss in the animal studies.
The discovery itself was powered by AI. Stanford’s Peptide Predictor analyzed more than 20,000 human protein-coding genes, searching for hidden biologically active peptides. From 2,683 candidates, researchers narrowed the list to just 100 for laboratory testing—and BRP emerged as the standout.
In obese mice, a single injection reduced food intake by up to 50% within one hour. After two weeks of treatment, the animals lost significant body fat while untreated mice continued gaining weight. The peptide also improved glucose tolerance and insulin sensitivity.
“Nothing we’ve tested before has compared to semaglutide’s ability to decrease appetite and body weight. We are very eager to learn if it is safe and effective in humans.” — Dr. Katrin Svensson
The findings are still preclinical, meaning BRP has not yet been tested in humans. But if future clinical trials confirm these results, it could represent a new generation of obesity treatments: delivering GLP-1-like benefits through a much more targeted biological pathway—with fewer unwanted side effects.
📄 Nature (2025)
#AI #Obesity #WeightLoss #Ozempic #Neuroscience #StanfordMedicine #science
Researchers at Stanford Medicine have used artificial intelligence to identify a naturally occurring human peptide that suppresses appetite and promotes weight loss in mice—while avoiding the major side effects commonly associated with GLP-1 drugs like Ozempic.
The newly discovered molecule, called BRP, is only 12 amino acids long. Yet in early laboratory experiments, it activated appetite-regulating neurons far more strongly than existing GLP-1 peptides.
Unlike semaglutide, which acts on receptors throughout the brain, gut, pancreas, and other tissues, BRP appears to target primarily the hypothalamus—the brain region responsible for regulating hunger and metabolism. That more focused mechanism may explain why researchers observed no signs of nausea, constipation, anxiety, or muscle loss in the animal studies.
The discovery itself was powered by AI. Stanford’s Peptide Predictor analyzed more than 20,000 human protein-coding genes, searching for hidden biologically active peptides. From 2,683 candidates, researchers narrowed the list to just 100 for laboratory testing—and BRP emerged as the standout.
In obese mice, a single injection reduced food intake by up to 50% within one hour. After two weeks of treatment, the animals lost significant body fat while untreated mice continued gaining weight. The peptide also improved glucose tolerance and insulin sensitivity.
“Nothing we’ve tested before has compared to semaglutide’s ability to decrease appetite and body weight. We are very eager to learn if it is safe and effective in humans.” — Dr. Katrin Svensson
The findings are still preclinical, meaning BRP has not yet been tested in humans. But if future clinical trials confirm these results, it could represent a new generation of obesity treatments: delivering GLP-1-like benefits through a much more targeted biological pathway—with fewer unwanted side effects.
📄 Nature (2025)
#AI #Obesity #WeightLoss #Ozempic #Neuroscience #StanfordMedicine #science
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👁️ Your Eyes May Have Evolved From an Ancient “Cyclops” Organ
Every vertebrate eye — including yours — may trace its origins to a single light-sensitive organ that sat in the middle of the head of a distant ancestor nearly 600 million years ago.
In a new Current Biology study, researchers from Lund University and the University of Sussex propose that an early worm-like ancestor lost its paired eyes after adopting a sedentary lifestyle. What remained was a simple median light-sensitive organ.
Millions of years later, as its descendants became active swimmers, evolution may have repurposed this central organ to form the paired retinas of vertebrates. The same ancestral system also appears to have given rise to the pineal gland, which today regulates our circadian rhythms and melatonin production.
If correct, this model could explain why vertebrate eyes are fundamentally different from those of insects and squid — and why the systems controlling vision and sleep may share a common evolutionary origin.
One important caveat: this is an evolutionary reconstruction, supported by anatomy, developmental biology, and neuroscience, rather than the discovery of a fossil “cyclops.”
📄 Paper: https://www.cell.com/current-biology/fulltext/S0960-9822(25)01676-8
#Evolution #Biology #Vision #Neuroscience #Science
Every vertebrate eye — including yours — may trace its origins to a single light-sensitive organ that sat in the middle of the head of a distant ancestor nearly 600 million years ago.
In a new Current Biology study, researchers from Lund University and the University of Sussex propose that an early worm-like ancestor lost its paired eyes after adopting a sedentary lifestyle. What remained was a simple median light-sensitive organ.
Millions of years later, as its descendants became active swimmers, evolution may have repurposed this central organ to form the paired retinas of vertebrates. The same ancestral system also appears to have given rise to the pineal gland, which today regulates our circadian rhythms and melatonin production.
If correct, this model could explain why vertebrate eyes are fundamentally different from those of insects and squid — and why the systems controlling vision and sleep may share a common evolutionary origin.
One important caveat: this is an evolutionary reconstruction, supported by anatomy, developmental biology, and neuroscience, rather than the discovery of a fossil “cyclops.”
📄 Paper: https://www.cell.com/current-biology/fulltext/S0960-9822(25)01676-8
#Evolution #Biology #Vision #Neuroscience #Science
Current Biology
Evolution of the vertebrate retina by repurposing of a composite ancestral median eye
The vertebrate retina differs dramatically from that in all other animal eyes. In
this review, Kafetzis et al. argue that, before the vertebrates, a series of lifestyle
changes in ‘our’ lineage led to the evolution of new lateral eyes, with a unique retinal…
this review, Kafetzis et al. argue that, before the vertebrates, a series of lifestyle
changes in ‘our’ lineage led to the evolution of new lateral eyes, with a unique retinal…
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👁️ Scientists Have Mapped the Wiring Behind Human High-Resolution Vision
Researchers have created the first complete cell-by-cell and synapse-level wiring map of the human fovea — the pinhead-sized region of the retina that lets us read, recognize faces and see fine detail in color.
The team reconstructed roughly 3,000 neurons and more than 300,000 connections, tracing how signals move through this tiny patch of nervous tissue. What they found was unexpectedly elegant: while much of the retina uses many overlapping pathways, the human fovea funnels visual information through just three major circuits.
That streamlined architecture may be one reason human central vision is so precise. The researchers describe it as more like an expressway than a maze of side streets — sacrificing redundancy for speed and efficiency.
The fovea is technically part of the central nervous system, which makes this the first complete connectivity map of a human CNS structure at this level of detail. Beyond basic neuroscience, the map could become a reference for treatments aimed at retinal diseases that destroy central vision.
We often talk about the brain as the organ that “sees.” But the first stage of high-resolution vision may already be doing far more sophisticated processing than we realized.
#Neuroscience #Vision #HumanBrain #Retina #Connectome #Science
https://www.pnas.org/doi/10.1073/pnas.2603286123
Researchers have created the first complete cell-by-cell and synapse-level wiring map of the human fovea — the pinhead-sized region of the retina that lets us read, recognize faces and see fine detail in color.
The team reconstructed roughly 3,000 neurons and more than 300,000 connections, tracing how signals move through this tiny patch of nervous tissue. What they found was unexpectedly elegant: while much of the retina uses many overlapping pathways, the human fovea funnels visual information through just three major circuits.
That streamlined architecture may be one reason human central vision is so precise. The researchers describe it as more like an expressway than a maze of side streets — sacrificing redundancy for speed and efficiency.
The fovea is technically part of the central nervous system, which makes this the first complete connectivity map of a human CNS structure at this level of detail. Beyond basic neuroscience, the map could become a reference for treatments aimed at retinal diseases that destroy central vision.
We often talk about the brain as the organ that “sees.” But the first stage of high-resolution vision may already be doing far more sophisticated processing than we realized.
#Neuroscience #Vision #HumanBrain #Retina #Connectome #Science
https://www.pnas.org/doi/10.1073/pnas.2603286123
PNAS
Approaching a connectome of the human foveal retina
The foveal retina is a unique primate specialization and a promising target for the first connectome of a human central nervous system structure. I...
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🧠 Singapore Just Opened a Data Center Powered by Living Human Neurons
This sounds like science fiction, but it went live on July 16.
Australian startup Cortical Labs, together with the National University of Singapore and data-center operator DayOne, has launched a biological computing facility where part of the processing is performed not by GPUs — but by living human neurons grown in a lab.
Inside are 20 CL1 biological computers. Each contains at least 200,000 neurons grown on a silicon chip covered with electrodes. The neurons originate from human blood cells that are reprogrammed into stem cells and then differentiated into neurons.
And yes, the computers have to be fed.
Every three days, technicians supply the cells with sugar, micronutrients and pH buffers, while a life-support system regulates oxygen, nitrogen and CO₂.
The strange part is that these neurons can actually learn.
Cortical Labs’ earlier DishBrain experiment showed human and mouse neurons learning to play Pong, with measurable learning appearing within just minutes. Earlier this year, developer Sean Cole connected around 200,000 human neurons to DOOM — allowing them to navigate the game and shoot at enemies.
Biology is nowhere near silicon in raw speed. But it has another advantage: efficiency.
A CL1 consumes around 30 watts. An NVIDIA H100 SXM can draw up to 700 W, while an eight-H100 server may consume roughly 10 kW including supporting hardware.
Cortical Labs also argues that biological neural networks may learn from far smaller datasets — closer to how humans adapt from limited experience.
Access to one CL1 currently costs about $2,200 per month. Cortical Labs already operates 120 units in Melbourne with around 20 paying customers, and Singapore could eventually expand to 1,000 biological computers.
So no, neurons aren’t replacing GPUs tomorrow.
But we have officially reached the stage where a data center needs electricity, an internet connection… and food.
Cyberpunk is becoming an engineering discipline.
#Biocomputing #Neuroscience #AI #DataCenters #CorticalLabs
https://www.straitstimes.com/tech/forget-silicon-chip-servers-singapores-newest-data-centre-needs-to-be-fed
This sounds like science fiction, but it went live on July 16.
Australian startup Cortical Labs, together with the National University of Singapore and data-center operator DayOne, has launched a biological computing facility where part of the processing is performed not by GPUs — but by living human neurons grown in a lab.
Inside are 20 CL1 biological computers. Each contains at least 200,000 neurons grown on a silicon chip covered with electrodes. The neurons originate from human blood cells that are reprogrammed into stem cells and then differentiated into neurons.
And yes, the computers have to be fed.
Every three days, technicians supply the cells with sugar, micronutrients and pH buffers, while a life-support system regulates oxygen, nitrogen and CO₂.
The strange part is that these neurons can actually learn.
Cortical Labs’ earlier DishBrain experiment showed human and mouse neurons learning to play Pong, with measurable learning appearing within just minutes. Earlier this year, developer Sean Cole connected around 200,000 human neurons to DOOM — allowing them to navigate the game and shoot at enemies.
Biology is nowhere near silicon in raw speed. But it has another advantage: efficiency.
A CL1 consumes around 30 watts. An NVIDIA H100 SXM can draw up to 700 W, while an eight-H100 server may consume roughly 10 kW including supporting hardware.
Cortical Labs also argues that biological neural networks may learn from far smaller datasets — closer to how humans adapt from limited experience.
Access to one CL1 currently costs about $2,200 per month. Cortical Labs already operates 120 units in Melbourne with around 20 paying customers, and Singapore could eventually expand to 1,000 biological computers.
So no, neurons aren’t replacing GPUs tomorrow.
But we have officially reached the stage where a data center needs electricity, an internet connection… and food.
Cyberpunk is becoming an engineering discipline.
#Biocomputing #Neuroscience #AI #DataCenters #CorticalLabs
https://www.straitstimes.com/tech/forget-silicon-chip-servers-singapores-newest-data-centre-needs-to-be-fed
The Straits Times
Forget silicon chip servers, Singapore’s newest data centre needs to be fed
Singapore’s first biological data centre uses lab-grown brain cells for energy-efficient computing, ideal for robotics and cybersecurity with limited data needs. Read more at straitstimes.com. Read more at straitstimes.com.
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🧠 Depression May Disrupt the Adult Brain’s Ability to Make New Neurons
For decades, scientists have suspected that depression may interfere with neurogenesis — the formation of new neurons in the adult hippocampus. Most of the strongest evidence, however, came from animal studies.
Now researchers have found evidence of the same process directly in human brains.
The team analyzed nearly 500,000 individual cell nuclei from hippocampal tissue donated by people with major depressive disorder and people without psychiatric illness. Using single-cell gene sequencing, chromatin analysis, spatial transcriptomics and protein measurements, they reconstructed what is effectively a molecular atlas of the hippocampus.
They found a lineage of cells consistent with ongoing adult neurogenesis — but in people with depression, that developmental process appeared to stall before new neurons fully matured. The surrounding hippocampal circuitry also showed signs of inflammation, cellular stress, disrupted synaptic plasticity, altered metabolism and an imbalance between excitatory and inhibitory signaling.
The finding could help explain something particularly characteristic of depression: the tendency for negative memories and experiences to dominate. New hippocampal neurons are thought to contribute to pattern separation — our ability to distinguish a new experience from similar memories in the past.
There is an important caveat: this study shows an association in post-mortem human brains. It does not prove that reduced neurogenesis causes depression, nor does it mean simply increasing neuron production would cure it.
But it moves one long-standing theory of depression from animal experiments much closer to human biology.
Depression may not simply change how neurons communicate.
It may change how the brain renews itself.
#Neuroscience #Depression #Brain #Neurogenesis #MentalHealth #Science
https://www.nature.com/articles/s41591-026-04571-8
For decades, scientists have suspected that depression may interfere with neurogenesis — the formation of new neurons in the adult hippocampus. Most of the strongest evidence, however, came from animal studies.
Now researchers have found evidence of the same process directly in human brains.
The team analyzed nearly 500,000 individual cell nuclei from hippocampal tissue donated by people with major depressive disorder and people without psychiatric illness. Using single-cell gene sequencing, chromatin analysis, spatial transcriptomics and protein measurements, they reconstructed what is effectively a molecular atlas of the hippocampus.
They found a lineage of cells consistent with ongoing adult neurogenesis — but in people with depression, that developmental process appeared to stall before new neurons fully matured. The surrounding hippocampal circuitry also showed signs of inflammation, cellular stress, disrupted synaptic plasticity, altered metabolism and an imbalance between excitatory and inhibitory signaling.
The finding could help explain something particularly characteristic of depression: the tendency for negative memories and experiences to dominate. New hippocampal neurons are thought to contribute to pattern separation — our ability to distinguish a new experience from similar memories in the past.
There is an important caveat: this study shows an association in post-mortem human brains. It does not prove that reduced neurogenesis causes depression, nor does it mean simply increasing neuron production would cure it.
But it moves one long-standing theory of depression from animal experiments much closer to human biology.
Depression may not simply change how neurons communicate.
It may change how the brain renews itself.
#Neuroscience #Depression #Brain #Neurogenesis #MentalHealth #Science
https://www.nature.com/articles/s41591-026-04571-8
Nature
Dysregulated adult hippocampal neurogenesis in major depressive disorder
Nature Medicine - The largest multiomic atlas of the adult human hippocampus identifies disrupted neurogenesis, gene regulation and neural circuits in major depressive disorder, revealing molecular...
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🧠 Scientists Replaced Most of a Mouse’s Cortex With Human Brain Tissue
This sounds like science fiction, but the experiment is real.
Stanford researchers genetically engineered mice so that most of their cerebral cortex and hippocampus never developed. The adult animals were left with only about 2% of the normal amount of corresponding cortical tissue.
Then, shortly after birth, scientists implanted tiny human cortical organoids — brain-like structures grown from human stem cells — into the empty space.
Three months later, more than 90% of the cortical tissue by volume was human-derived.
And it did not simply sit there.
Human neurons became integrated into the mouse nervous system, developed organized electrical activity and sent long-range projections — some extending as far as the spinal cord. The mice retained broadly normal movement, although researchers found specific differences in coordination and spontaneous behavior.
Then came an unexpected discovery.
Inside the transplanted human tissue, researchers found cells resembling von Economo neurons — extremely rare, large neurons associated with brain regions involved in social awareness and decision-making. They occur in humans, great apes, elephants, dolphins and whales, but scientists had never previously succeeded in generating them in laboratory brain cultures.
The team also demonstrated why the model could matter medically. When the animals experienced several hours of reduced oxygen, the human cortical tissue was severely damaged while comparable mouse tissue was largely spared — potentially giving researchers a living model for studying why the developing human brain is particularly vulnerable to oxygen deprivation.
An important distinction: these are not mice with human intelligence or a human brain. The transplanted tissue remained developmentally immature, and the experiment provides no evidence of human-like cognition or consciousness. It is a new animal model for studying human neural development and disease.
But the boundary scientists have crossed is remarkable.
We can now grow substantial amounts of developing human neural tissue not just in a dish —
but inside a living brain, connected to a living nervous system.
Where should the ethical boundary for experiments like this be?
#Neuroscience #Brain #Organoids #StemCells #Biotechnology #Stanford #Science
https://www.nature.com/articles/s41586-026-11032-2
This sounds like science fiction, but the experiment is real.
Stanford researchers genetically engineered mice so that most of their cerebral cortex and hippocampus never developed. The adult animals were left with only about 2% of the normal amount of corresponding cortical tissue.
Then, shortly after birth, scientists implanted tiny human cortical organoids — brain-like structures grown from human stem cells — into the empty space.
Three months later, more than 90% of the cortical tissue by volume was human-derived.
And it did not simply sit there.
Human neurons became integrated into the mouse nervous system, developed organized electrical activity and sent long-range projections — some extending as far as the spinal cord. The mice retained broadly normal movement, although researchers found specific differences in coordination and spontaneous behavior.
Then came an unexpected discovery.
Inside the transplanted human tissue, researchers found cells resembling von Economo neurons — extremely rare, large neurons associated with brain regions involved in social awareness and decision-making. They occur in humans, great apes, elephants, dolphins and whales, but scientists had never previously succeeded in generating them in laboratory brain cultures.
The team also demonstrated why the model could matter medically. When the animals experienced several hours of reduced oxygen, the human cortical tissue was severely damaged while comparable mouse tissue was largely spared — potentially giving researchers a living model for studying why the developing human brain is particularly vulnerable to oxygen deprivation.
An important distinction: these are not mice with human intelligence or a human brain. The transplanted tissue remained developmentally immature, and the experiment provides no evidence of human-like cognition or consciousness. It is a new animal model for studying human neural development and disease.
But the boundary scientists have crossed is remarkable.
We can now grow substantial amounts of developing human neural tissue not just in a dish —
but inside a living brain, connected to a living nervous system.
Where should the ethical boundary for experiments like this be?
#Neuroscience #Brain #Organoids #StemCells #Biotechnology #Stanford #Science
https://www.nature.com/articles/s41586-026-11032-2
Nature
Developmental xenocortication using human-derived organoids in mice
Nature - Xenocortication with human neurons enables circuit- and behaviour-level analysis of neurodevelopment in mice.
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🧠 Just 10 Minutes With AI Can Make You Give Up More Easily
AI makes us faster.
But what happens when we suddenly have to think without it?
A newly peer-reviewed study involving 1,222 participants suggests something uncomfortable: after just 10–15 minutes of AI-assisted problem-solving, people performed worse on their own — and were more likely to give up.
Researchers conducted three randomized experiments involving mathematics and reading comprehension. Some participants solved problems independently, while others had access to ChatGPT. Initially, the AI-assisted group performed better. But when researchers unexpectedly removed the chatbot, the advantage disappeared. In the first experiment, participants who had used AI correctly solved just 57% of subsequent problems, compared with 73% among those who had worked independently. They also skipped nearly twice as many questions: 20% versus 11%.
The researchers identified an especially interesting pattern. Participants who used AI primarily to obtain complete answers struggled more afterward than those who used it for hints or explanations. That comparison was observational, not a separate randomized experiment, but it suggests an important distinction: AI that helps you think may be very different from AI that thinks for you.
The possible explanation is a psychological shift. When answers arrive instantly, independent effort begins to feel unnecessarily difficult. Researchers call attention to the loss of productive struggle — the mental work through which we develop skills and persistence.
Important caveat: The experiments measured immediate effects during short online tasks. They do not establish permanent cognitive damage or show that regular AI use necessarily makes people less intelligent. Whether these effects persist over weeks or months remains unknown.
But the implication is fascinating.
We may be building machines that make us extraordinarily productive while quietly changing how willing we are to solve problems ourselves.
Perhaps the smartest AI assistant isn’t the one that always gives you the answer.
It’s the one that sometimes makes you figure it out.
Would you prefer an AI that solves everything instantly — or one that occasionally forces you to think?
#AI #ChatGPT #Psychology #Neuroscience #CognitiveScience #ArtificialIntelligence #Science
https://arxiv.org/abs/2604.04721
AI makes us faster.
But what happens when we suddenly have to think without it?
A newly peer-reviewed study involving 1,222 participants suggests something uncomfortable: after just 10–15 minutes of AI-assisted problem-solving, people performed worse on their own — and were more likely to give up.
Researchers conducted three randomized experiments involving mathematics and reading comprehension. Some participants solved problems independently, while others had access to ChatGPT. Initially, the AI-assisted group performed better. But when researchers unexpectedly removed the chatbot, the advantage disappeared. In the first experiment, participants who had used AI correctly solved just 57% of subsequent problems, compared with 73% among those who had worked independently. They also skipped nearly twice as many questions: 20% versus 11%.
The researchers identified an especially interesting pattern. Participants who used AI primarily to obtain complete answers struggled more afterward than those who used it for hints or explanations. That comparison was observational, not a separate randomized experiment, but it suggests an important distinction: AI that helps you think may be very different from AI that thinks for you.
The possible explanation is a psychological shift. When answers arrive instantly, independent effort begins to feel unnecessarily difficult. Researchers call attention to the loss of productive struggle — the mental work through which we develop skills and persistence.
Important caveat: The experiments measured immediate effects during short online tasks. They do not establish permanent cognitive damage or show that regular AI use necessarily makes people less intelligent. Whether these effects persist over weeks or months remains unknown.
But the implication is fascinating.
We may be building machines that make us extraordinarily productive while quietly changing how willing we are to solve problems ourselves.
Perhaps the smartest AI assistant isn’t the one that always gives you the answer.
It’s the one that sometimes makes you figure it out.
Would you prefer an AI that solves everything instantly — or one that occasionally forces you to think?
#AI #ChatGPT #Psychology #Neuroscience #CognitiveScience #ArtificialIntelligence #Science
https://arxiv.org/abs/2604.04721
arXiv.org
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