Tiny lab-grown brain models and the particles they release may reveal hidden differences among Alzheimer’s patients. Personalized treatment remains one of the biggest challenges in Alzheimer’s disease. Two patients can receive the same medication for symptoms such as depression, anxiety, or agitation and experience very different outcomes, leaving doctors with few ways to predict who [...]
Researchers at NYU Langone Health recorded the activity of hundreds of neurons simultaneously across several brain regions in mice. By tracking how signals move from the hippocampus to the neocortex, where long-term memories are kept, they found that a subset of hippocampal neurons appears to participate in routing information between regions in distinct patterns. These cells participate in both incoming and outgoing signaling, but do so using distinct patterns of activity.
Separate Channels Through the Same Cells
The study focused on a series of interconnected brain regions: CA3, which processes rapidly changing information; CA1, which serves as a central hub; and the retrosplenial cortex, which is important for navigation and spatial memory. About one in four CA1 neurons receives most of the signals from CA3. When these same neurons send signals to the retrosplenial cortex, they fire in a different pattern, creating a separate outgoing channel using the same cells.
Rather than using new neurons, the brain separates these channels by changing how the same neurons fire together. The researchers suggest this arrangement may help reduce interference between new learning and more stable cortical memories.
“Our findings help explain how memory can be both moldable and enduring,” said co-lead author Joaquín Gonzalez, PhD, a postdoctoral fellow in the Department of Psychiatry at NYU Grossman School of Medicine. “By changing how the same cells fire together instead of turning on new cells, the brain can keep information organized and protect older memories.”
What Happens During Sleep
The CA1 neurons involved in learning during the day also stay active at night. The researchers found that these cells remain busy during sleep events called sharp-wave ripples, which are bursts of activity the hippocampus uses to replay and strengthen memories from the day.
Since overlapping neurons are recruited during both waking activity and sleep replay, the same circuit elements appear to participate in both learning and consolidation. This theoretically allows the brain to use a single system for both learning and storing memories, without the two processes interfering with each other.
“Our study shows how learning and memory consolidation can coexist in the same network,” said co-lead author Mihály Vöröslakos, MD, PhD. “Our discovery was made possible because for the first time, we were able to record hundreds of individual neurons across all the key regions simultaneously in animals that were moving around naturally.”
Implications for Disease and AI
The system identified in this research may help explain how memory disorders begin. In Alzheimer’s disease, for example, the hippocampal circuits examined here are some of the earliest to deteriorate. These networks are essential for sorting and organizing new experiences.
“Our discovery of a ‘memory switchboard’ deep in the hippocampus may provide clues as to how memory circuits fail in Alzheimer’s disease,” said co-senior author Zhe S. Chen, PhD, a professor in the Departments of Psychiatry and Neuroscience at NYU Grossman School of Medicine.
Artificial intelligence systems have a hard time holding onto what they’ve already learned when faced with new tasks, a problem researchers call catastrophic forgetting. The human brain appears able to update memories without catastrophic forgetting by altering the use of existing neural circuits. By studying how our brains pull this off, scientists hope to design AI that can keep learning new things without forgetting the old.
“By showing how the mammalian brain can safeguard memories during learning, our research may offer a biological blueprint for designing next-generation AI technology that can update itself continuously without overwriting what it has already acquired,” said co-senior author György Buzsáki, MD, PhD, the Biggs Professor of Neuroscience at NYU Grossman School of Medicine.
The researchers plan to investigate whether similar switchboard-like channels exist in other memory circuits. The authors caution that their findings in mice under controlled conditions do not yet allow conclusions about the human brain.
Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.
Brain scans have uncovered two biologically distinct forms of autism hidden within the spectrum. An international team of researchers has identified at least two biologically distinct forms of autism by examining how different regions of the brain communicate with one another. The findings could help advance more precise and personalized approaches to autism care and [...]
Researchers have uncovered a previously underappreciated mechanism involved in Alzheimer’s disease and developed a compound that interrupts it. For decades, Alzheimer’s research has largely focused on amyloid plaques and tau tangles, the protein abnormalities that accumulate in the brain as the disease progresses. Yet despite billions of dollars in research and numerous drug development efforts, [...]
When you imagine a waterfall, what comes to mind? Maybe a misty cascade into a blue pool surrounded by trees. Perhaps the roar of water splashing down, as well. It’s a big mystery how brain activity differs when imagining a waterfall versus seeing or hearing one in real life. Brain scans now suggest some activity when you imagine something is similar to what happens when you see or hear the real thing.
But that overlap did not appear in brain areas that deal with single senses. Instead, it showed up in high-level brain networks. These are ones that handle inputs from multiple types of senses.
Researchers shared these findings March 31 in Neuron.
Imagining a scene such as this one activates various areas of the brain, a new study shows. sara_winter/iStock/Getty Images Plus
Neuroscientist Rodrigo Braga led the research. “When I was a teenager,” he says, “I remember the first time realizing that there’s like a voice I can hear in my head.” This “internal monologue” narrates one’s own thoughts.
“That’s really strange,” Braga recalls thinking. “Why is it that we experience those thoughts and sensations almost as if we’re perceiving them?”
He’s spent years trying to answer that question. He now works at Northwestern University’s Feinberg School of Medicine. It’s in Chicago, Ill. In a new study, his team asked eight people to imagine scenes, faces, someone else speaking, their own internal monologues and other sounds. All the while, an MRI machine scanned their brains.
Having hours of MRI data on all eight people allowed the team to create individualized brain maps for each. These showed how each person’s brain activity changed during imagination.
The imagination prompts that people got were open-ended. One was: “Imagine a castle on a hill.” Another: “Imagine a rock song playing on the radio.” After each prompt, the scientists asked people what they saw and heard in their heads. The questions probed how vivid each imagined experience had been — how clear and realistic it felt.
After completing the brain scans, Braga’s team asked follow-up questions. These explored what made some mental images more vivid than others.
Under the hood of imagination
The researchers grouped their data into two buckets. In one, they put the data on imagined locations and events. In the other, they grouped the data on imagined speech and language.
When people were thinking about locations or events, they reported highly vivid sights in their mind’s eye. Activity also went up in their brains’ “default network A.” This is a system of nerve cells in the brain — neurons — known to process real spatial information.
When people thought about speech or language, they reported hearing highly vivid sounds in their heads. Activity also spiked in their brains’ language network. This system of neurons is usually involved when someone reads or listens to speech.
In short, imaginary sights and sounds both enlisted parts of the brain used to process real experiences.
But imagined sensations did not activate sight- and sound-specific parts of the brain. Rather, the default network A and language network respond to new information — no matter what sense it had entered through.
Other studies have found that when someone imagines a certain object they’ve just seen, vision-specific brain regions light up. In this study, prompts to imagine more general scenes did not do that.
That might be because the basic visual areas of the brain respond to details like edges, colors and lines, says Nathan Anderson. Those fine details might matter when someone is asked to picture a real object they saw. But, he notes, “people don’t necessarily imagine fine details when they are imagining a [general] scene.” So the neurons that handle specific visual details aren’t needed. Anderson is a neuroscientist who took part in the study. He works at Brigham Young University in Provo, Utah.
These findings don’t surprise Stephen Kosslyn. Since the prompts didn’t ask people to imagine detailed sights or sounds, he says it makes sense that the brain regions linked to those tasks didn’t light up. Kosslyn is a neuroscientist at Harvard University in Cambridge, Mass. He did not take part in the new work.
Open-ended prompts are a strength of the study, says Alfredo Spagna. A psychologist, he works at John Cabot University in Rome, Italy, and did not take part in the study. Everyday mental imagery is likely closer to imagining a castle on a hill than it is to picturing the tiny details of something you just saw, he says. So the open-ended prompts used here probably closely mimic what’s happening in our brains day-to-day.
But there’s still much to learn about how the brain conjures sights and sounds that feel so real. “This is one of the many papers that will come out in the next years that try to break down this obscure concept of vividness,” says Spagna.
Researchers at LMU have found a new type of electricalrhythm in the central thalamus, a small area deep inside the brain. Published in Nature Human Behaviour, the study suggests that this rhythm could serve as a biological indicator of conscious states.
A Signal That Tracks Awareness
This rhythm allows researchers to closely track certain states of consciousness. It appears during wakefulness and REM sleep, but disappears as soon as non-REM sleep begins. In non-REM sleep, slower brain waves take over, and the thalamic signal fades.
The signal does more than just appear with consciousness. It also changes as the brain moves between different states. For example, the rhythm becomes stronger during REM sleep, which lets researchers see small shifts in awareness even within the same stage of sleep.
“Our results show that the central thalamus plays an important role in regulating brain states,” said Dr. Aditya Chowdhury, lead author of the study. “In the context of existing research, our results show that this small deep-lying brain structure could actively influence our states of consciousness.”
Professor Tobias Staudigl, who led the research team, argues the signal’s consistency makes it more than just an interesting discovery. “These characteristic rhythm patterns can be reliably attributed to specific states and thus have the potential to serve as a measurable biological signature of states of consciousness,” Staudigl said.
Getting Inside the Deepest Part of the Brain
Recording electrical activity from deep brain structures is one of neuroscience’s most persistent technical problems. Standard surface EEG can detect general patterns from the brain’s outer layers, but it misses details from deeper areas. Since the thalamus sits at the center of the brain, it has remained largely inaccessible through non-invasive methods.
The LMU team had a rare chance to study this. Their research involved patients already undergoing deep-brain stimulation therapy for epilepsy, which uses electrodes in the thalamus to help control seizures. These electrodes let the researchers record signals directly from inside the thalamus, something that is almost never possible otherwise.
The team combined these recordings with surface EEG, eye-tracking, and detailed sleep-stage analysis. This approach allowed them to see how thalamic activity changes as patients transition between wakefulness and different sleep stages. Their findings offer the most detailed picture yet of what the thalamus actually does as consciousness changes.
Medical Implications
Disorders of consciousness, like coma, vegetative state, and minimally conscious state, are some of the hardest problems in neurology. One reason is that doctors have lacked reliable biological markers to assess patients’ awareness. The thalamic rhythm found in this study could help solve that problem.
If this signal truly tracks brain states linked to consciousness, it could help doctors evaluate awareness in patients who cannot communicate, guide treatment choices, and monitor how patients respond to care over time. The researchers believe it could also be used to improve deep brain stimulation therapy by allowing doctors to adjust treatment based on real-time thalamic activity rather than general clinical signs.
Staudigl was recently awarded funding by the European Research Council to explore the clinical potential of this discovery and to develop applications for treating neurological disease.
Understanding consciousness has always been one of science’s most difficult challenges. While the study does not answer the fundamental question of what consciousness is, these findings provide a consistent, measurable signal that indicates how the brain moves between conscious and unconscious states.
Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.
Synesthesia is a trait that some people have in which one kind of sensory input triggers other senses. To someone with synesthesia, different colors may have different tastes. Or hearing certain sounds may cause them to see certain shapes.
This phenomenon is not a mental illness. Rather, it is considered a form of neurodiversity. Up to 4 percent of people may have some form of synesthesia.
This trait takes many forms. Grapheme-color is one type. This means that a person sees letters or numbers in different colors. For instance, when a person sees the number 7, it may always appear yellow. About 1 percent of people share this trait.
Another type is called chromesthesia. That’s when hearing a sound causes a person to see colors or shapes around them. Historians think that Vincent van Gogh, a 19th-century painter, may have had this trait. He described seeing colors around him when he played the keys of a piano.
Other famous artists, such as singer and songwriter Billie Eilish, have described this experience, too. “Everything that I make I’m already thinking of what color it is, and what texture it is, and what day of the week it is, and what number it is, and what shape,” the musician told iHeart Radio.
Scientists are not sure exactly what causes synesthesia. But they believe it is at least partly linked to a person’s genes.
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By tracking eye movements in zebrafish, researchers identified four different types of sleep, analogous to the complex sleep patterns of humans and other animals.
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Tiny lab-grown brain models and the particles they release may reveal hidden differences among Alzheimer’s patients. Personalized treatment remains one of the biggest challenges in Alzheimer’s disease. Two patients can receive the same medication for symptoms such as depression, anxiety, or agitation and experience very different outcomes, leaving doctors with few ways to predict who [...]