Tag Archives: Neurons

Animal Studies Indicate That Memory Evolves Across Neurons Over Time

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New research by neurobiologists at Northwestern University and the University of Illinois Urbana-Champaign reveals that the brain’s internal GPS changes as individuals navigate familiar environments. These findings shed light on the essential mystery of how the brain encodes and retains spatial memories, influencing scientists’ perspectives on memory, learning, and even aging.

Memories navigating familiar paths are more fluid than previously thought and activate different neurons on each journey. Image credit: Zeinab vessel.

“Our study confirms that the spatial memories in the brain are not fixed but rather dynamic,” stated Professor Daniel Dombeck from Northwestern University.

“You can’t simply point to a specific group of neurons and claim that their memories are located there.”

“We are uncovering the fact that memories shift between neurons over time.”

“The same experience triggers different neurons each time. It’s not an abrupt change; it evolves gradually.”

The hippocampus, situated deep within the temporal lobe, is integral for storing memories related to spatial navigation.

For many years, neurobiologists believed that the same hippocampal neurons encoded the same memory in a consistent location.

This led to the assumption that a person’s route from the bedroom to the kitchen would activate identical neuron sequences during a midnight quest for water.

However, about a decade ago, researchers studied the brains of mice traversing a maze.

Despite running through the identical maze daily, different neurons fired with each run, prompting scientists to question whether this outcome was an anomaly. Perhaps the mice’s experiences were affected by subtle environmental cues.

To delve deeper into these inquiries, Professor Dombeck and his team devised an experiment that meticulously controlled mouse sensory input.

The mice navigated a virtual maze on a treadmill, allowing precise measurements of their speed.

The maze was presented through a multisensory virtual reality platform developed by the researchers.

This setup ensured that the mice experienced the same visual stimuli and odors during all sessions, minimizing environmental variability.

After conducting multiple trials, the results indicated a different set of neurons activated each time, even in the highly controlled virtual setting.

This revelation confirms that the brain’s spatial mapping is inherently dynamic, constantly adapting, even in supposedly stable settings.

“Our findings suggest that memory is fluid,” commented Jason Climer, a professor at the University of Illinois at Urbana-Champaign.

“This ties into a broader question regarding modern AI and why the brain can learn and adapt in ways machines struggle with.”

“It may also be linked to natural forgetting, which is often overlooked but essential for healthy memory function.”

While there were few discernible patterns throughout the experiment, one consistent observation emerged. The more excitable neurons were more successfully activated, leading to stable spatial memory across multiple sessions in the virtual mazes.

Given that neuronal excitability diminishes with age, this finding aids in understanding how aging and related diseases impact the brain’s ability to form new memories.

“The small clusters of stable neurons are unique, and gaining insights into what makes them special could pave the way for new treatments for memory disorders,” stated Professor Climer.

“Memory impairment is a hallmark of Alzheimer’s disease and presents significant challenges for individuals with various neuropsychiatric conditions, such as schizophrenia.”

“By deepening our understanding of fundamental memory aspects, like temporal changes highlighted in our study, we can identify new targets for understanding brain differences in these patients and develop new treatment strategies.”

“Learning about how the brain deals with memory challenges can also inform improvements in computers and AI.”

Survey results were published in the journal on July 23, 2025, in Nature.

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JR Climer et al. The hippocampus expression drifts in a stable, multisensory environment. Nature Published online on July 23, 2025. doi:10.1038/s41586-025-09245-y

Source: www.sci.news

Cancer Cells Hijack Mitochondria from Neurons to Fuel Their Growth

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Neurons Growing Among Cancer Cell Cultures (Stained Green)

Simon Grelet and Gustavo Ayala

Cancer cells are known to hijack energy-generating components from neurons, facilitating their spread to remote locations. This groundbreaking discovery may enhance treatments for the most aggressive tumors.

“This marks the first instance of mitochondrial transfer from nerves to cancer cells,” states Elizabeth Lepasky, who is not directly linked to the study conducted at the Roswell Park Comprehensive Cancer Center in Buffalo, New York. “This signifies a pivotal advancement in cancer neuroscience, a rapidly evolving field.”

Prior knowledge indicated that both intratumor and adjacent tumors produce proteins and electrical impulses that promote cancer growth and dissemination. “A higher density of nerves within tumors correlates with a poorer prognosis,” says Simone Grelet from the University of Southern Alabama.

Earlier investigations have demonstrated that brain tumor cells can absorb mitochondria (the energy-producing organelles) from non-neuronal brain cells. However, the potential for tumor cells to extract mitochondria from neurons remained unclear, according to Grelet.

To explore this, Grelet and his team genetically modified breast cancer cells derived from mice to contain red fluorescent molecules and combined them with mouse neurons that had mitochondria labeled with green pigments in laboratory conditions. Imaging revealed that cancer cells can seize mitochondria from neurons within a matter of hours.

“Cancer cells extend their membranes to absorb mitochondria from neurons,” explains Grelet. “It’s akin to a lineup of mitochondria filtering through a narrow passage, entering the cancer cells sequentially.”

To assess whether this phenomenon occurs in vivo, the researchers injected red breast cancer cells into the mammary glands of female mice to induce tumor growth. They also genetically engineered the surrounding nerves to carry green mitochondria. Approximately one month later, 2% of the cancer cells in these tumors had taken up mitochondria from neurons.

Conversely, 14% of tumor cells that metastasized to the brain exhibited neuronal-derived mitochondria. This suggests that cancer cells acquiring mitochondria from nerves have a significant advantage over other cancer types. Further tests indicate that these mitochondria contribute to greater resilience against the physical and chemical challenges encountered in the bloodstream.

“Cancer cells face numerous hurdles in their migration,” remarks Repasky. “They must escape the primary tumor, navigate barriers to blood vessels, exit the bloodstream, and secure sufficient oxygen and nutrients at secondary sites. By appropriating mitochondria, it appears cancer cells can endure this tumultuous journey,” she adds.

To determine if this process also occurs in humans, researchers examined tumor samples from eight women with metastatic breast cancer. They discovered that tumor cells from distant sites contained, on average, 17% more mitochondria compared to those from breast tumors, suggesting that similar mechanisms are at play in patients, according to Grelet.

Moreover, the team analyzed human prostate tumor samples and observed that cancer cells near nerves contained significantly more mitochondria than those situated further away. “I believe this represents a common mechanism utilized by various tumor types,” asserts team member Gustavo Ayala from the University of Texas Health Science Center in Houston.

The findings indicate that inhibiting mitochondrial transfer could potentially curtail the spread of the deadliest tumors. “We are optimistic that this is achievable, at least for certain tumor types,” Repasky suggests. Ayala mentions that they are working towards developing a drug to facilitate this approach.

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Source: www.newscientist.com

Scientists discover 16 different types of neurons responsible for human sense of touch

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A new study led by scientists from the University of Pennsylvania, Karolinska Institutet, and Linköping University has revealed a landscape view of the human sense of touch.

Somatosensory diversity arises from heterogeneous dorsal root ganglion (DRG) neurons. However, the cell body transcriptome, a key piece of information for deciphering the function of individual human (h)DRG neurons, is lacking due to technical difficulties. In a new study, Yu others. They isolated somatic cells from individual hDRG neurons and performed deep RNA sequencing (RNA-seq) to detect an average of more than 9,000 unique genes per neuron, identifying 16 types of neurons.

Humans perceive touch, temperature, and pain through the somatosensory system.

The general understanding is that there are specific types of neurons for each type of emotion, such as pain, pleasant touch, or coldness.

But new research casts doubt on that notion and shows that bodily sensations are probably much more complex than that.

“Much of the knowledge we have today about how the nervous system works comes from studies of animals,” said Dr. Wenqing Luo of the University of Pennsylvania and colleagues.

“But how similar are mice and humans, for example?”

“Many discoveries made in animal studies have not been confirmed in human studies.”

“One reason for this may be a lack of understanding of how it works in the human body.”

“We wanted to create a detailed atlas of the different types of neurons involved in somatosensation in humans and compare it with neurons in mice and the primate macaque.”

The study involved a detailed analysis of the genes used by individual neurons, so-called deep RNA sequencing.

Neurons with similar gene expression profiles were grouped as one sensory neuron type.

In this way, the researchers identified 16 unique human neuron types.

This study is the first to link gene expression and actual function in different types of neurons.

To investigate the function of neurons, the scientists used microneurography techniques to listen to the signals of one neuron at a time.

Using this technique, skin neurons in awake participants are exposed to temperature, touch, or certain chemicals, and individual neurons are “listened in” to determine how those particular neurons respond and send signals to the brain. You can find out if it is.

During these experiments, the authors made discoveries that would not have been possible if mapping the cellular machinery of different types of neurons had not given them new ideas for experiments.

One such discovery concerns a type of neuron that responds to pleasant touch.

The researchers discovered that this cell type unexpectedly responded to heat and also to capsaicin, the chemical that gives chili peppers their heat.

Scientists were surprised that the touch-sensing neurons responded to such stimuli, since their response to capsaicin is typical of pain-sensing neurons.

Additionally, this type of neuron also responded to cooling, even though it does not produce the only protein known to date that signals the perception of cold.

This finding cannot be explained by what is known about cellular mechanisms and suggests that there are other mechanisms for detecting colds that have yet to be discovered.

The authors speculate that these neurons form an integrated sensory pathway that produces pleasurable sensations.

“We have been listening to the neural signals from these neurons for 10 years, but we knew nothing about their molecular characteristics,” said Dr. Håkan Ólausson from Linköping University.

“This study shows us what kinds of proteins these neurons express and what kinds of stimuli they can respond to, and we can now make connections between them. Moving forward.”

Another example is a type of pain-sensing neuron that conducts very rapidly and has been shown to respond to non-painful cooling and menthol.

“There is a common understanding that neurons are very specialized: one type of neuron detects cold, another type detects specific vibrational frequencies, a third type responds to pressure, and so on.” said Dr. Saad Nagy, also from Linköping University.

“That's how people often talk about it. But it turns out it's much more complicated than that.”

So how do mice, macaques, and humans compare? How similar are we? Many of the 16 types of neurons the researchers identified in their study are largely similar across species.

The biggest difference they found was that conduction in pain-sensing neurons was much faster in response to stimuli that could cause injury.

Compared to mice, humans have more pain neurons, a type of neuron that sends pain signals to the brain at high speeds.

“Our study doesn't answer why this is the case, but we have a theory,” Dr. Ólausson said.

“The fact that pain signals are emitted at a much faster rate in humans compared to mice is probably just a reflection of their body size.”

“Mice don't need such rapid neural signaling. But in humans, the distances are longer and the signals need to be sent to the brain more quickly, before reacting and withdrawing.” You will be injured.”

Regarding this research, paper in diary natural neuroscience.

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H. Yu others. Utilizing deep sequencing of single cell somatic RNA to explore the neural basis of human somatosensation. nut neurosipublished online on November 4, 2024. doi: 10.1038/s41593-024-01794-1

Source: www.sci.news

Injecting Neurons into Rats Gives Mice the Ability to Smell Cookies, Despite Their Lack of Olfactory Function.

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Mouse brain hippocampus (red) containing some rat cells

M. Kadish Imtiaz/Columbia University Irving Medical Center (CC BY-NC-ND)

Rat cells grown in the brains of mice without a sense of smell have enabled them to acquire the sense of smell. This is the first time that one species has experienced the world through the sensory neurons of another species.

When cells of one species multiply within the body of another species, the resulting organism is known as an interspecies chimera. These have previously been used to study specific tissues, such as mice containing cells of the human immune system, to study disease responses. However, creating chimeras of other tissues, such as neural tissue, is more complex.

Researchers at the University of Texas Southwestern Medical Center previously bred mice with parts of rat brains transplanted into them. Now, another team of researchers has shown that this cross-species chimerism may confer the ability to smell in mice genetically modified to lack scent-sensing neurons.

christine baldwin The researchers at Columbia University in New York injected these engineered mouse embryos with rat stem cells. Once the embryos became adult mice, the researchers monitored neuronal activity. The researchers discovered that these animals have functional neural pathways for sensing odors, made up of both rat and mouse cells that can communicate directly with each other.

When researchers tested these mice's sense of smell by searching for hidden mini Oreo cookies, they found that the mice that received stem cell injections found the food more easily, as opposed to the same genetically modified mice. It turned out that it was possible. It wasn't a chimera.

“This is a huge opportunity for human health, allowing us to better understand how to create cell replacement therapies for humans,” Baldwin said. “We can also create models in mice and rats for diseases that affect long-lived organisms.”

The fact that rat cells were able to facilitate food exploration in mice, which normally don't have a sense of smell, is very impressive, he says. walter lowe at the University of Minnesota. “Now, it is not yet clear whether something similar to this can occur in even different species, but at least [this study] Shows what's happening in two relatively close species [in evolutionary terms]” he says.

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Source: www.newscientist.com