Sleep Cleansing - Microbiota & Anxiety - Street Rats

[Breedlove, S]

https://www.scientificamerican.com/article/how-sleep-cleans-the-brain-and-keeps-you-healthy/

How Your Brain’s Nightly Cleanse Keeps It Healthy

By Lydia Denworth 

A remarkably bright pulsing dot has appeared on the monitor in front of us. We are watching, in real time, the brain activity of a graduate student named Nick, who is having an afternoon nap inside an imaging machine at the Massachusetts Institute of Technology, where Lewis has her laboratory.

The bright spot first appears toward the bottom of the screen, about where Nick’s throat meets his jaw. It moves slowly upward, fades and then is followed by another bright dot. “It really comes and goes,” says Lewis, who is also affiliated with Massachusetts General Hospital. “It’s in waves.” This moving dot depicts something few people have ever seen: fresh cerebrospinal fluid flowing from the spinal cord into the brain, part of a process that researchers are now learning is vital for keeping us healthy.

For decades biologists have pondered a basic problem. As human brains whir and wonder throughout the day, they generate waste—excess proteins and other molecules that can be toxic if not removed. Among those proteins are amyloid beta and tau, key drivers of Alzheimer’s disease. Until recently, it was entirely unclear how the brain takes out this potentially neurotoxic trash.

In the rest of the body, garbage removal is handled initially by the lymphatic system. Excess fluid and the waste it carries move from tissue into the spleen, lymph nodes and other parts of the system, where certain particles are removed and put into the bloodstream to be excreted. It was long thought that the brain can’t use the same trick, because the so-called blood-brain barrier, a protective border that keeps infections from reaching critical neural circuitry, stops the transport of most everything in and out.


© 2025 SCIENTIFIC AMERICAN, 
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https://www.nature.com/articles/d41586-025-02633-4

Why nurturing the gut microbiota could resolve depression and anxiety

    Simon Makin 

Andrew Moseson experienced severe depression for many years. “Some days I wasn’t able to get out bed. I had long periods of unemployment and was living in my car for a time.” He struggled to find relief, nothing worked. “I tried medications, exercise, volunteering, psychedelics. I read books about happiness, about depression,” he says. “Everything helped a little, but it was still there.” Then, in the spring of 2023, he found a clinical trial that would change his life.

The trial was for people with clinical depression who, like Moseson, had not found success with existing medication. It involved faecal microbiota transplantation (FMT), in which stool from a healthy donor is transferred into a recipient’s gastrointestinal tract to restore a healthy balance of gut bacteria.

The procedure did not work as well for everyone who took part in the trial, but for Moseson the results were transformative — and they came fast. “Within about a week, I started feeling better,” he says. “I felt like my brain was refreshed.”

Two years later, Moseson is still taking his previously prescribed medication. “My doctor doesn’t want me to quit my antidepressants,” he says. “There’s a thought that this transplant could make antidepressants work better.” Whatever the mechanism, the change seems stark. “I feel like I’ve been cured,” Moseson says.

Numerous psychiatric and neurological conditions have been linked to disturbances in people’s gut microbiota — the community of trillions of microorganisms that live symbiotically in the gastrointestinal tract. These are just correlations, but studies in rodents show compelling evidence of causality, and other animal research points to multiple pathways through which the microbiota communicates with the brain.

© 2025 Springer Nature Limited

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https://www.thetransmitter.org/social-cognition/hitting-city-streets-to-record-rat-behaviors-qa-with-emily-mackevicius-ralph-peterson/

 Hitting city streets to record rat behaviors

By Marta Hill

Most people flinch when a rat scurries into their path, but not one New York City-based research team: These researchers actively seek out urban rats to study their day-to-day behaviors and interactions. The work is part of a growing trend of neuroscientists studying animals in their natural environments rather than in the lab.

“It’s a classic neuroscience model organism, but we don’t really know that much about their natural ecology,” says team member Emily Mackevicius, senior research scientist at Basis Research Institute.

The fact that urban rats are ubiquitous presents a convenient opportunity for naturalistic study, adds Ralph Peterson, a postdoctoral fellow at the institute, who is also part of the team.

Last year, Peterson, Mackevicius and their colleagues held a series of rat behavior stakeouts around New York City—in the Union Square subway station, in a wooded area of Central Park and on a street corner in Harlem. The team used thermal cameras to track the animals as they foraged in the dark and ultrasonic audio recorders to eavesdrop on rat vocalizations.

Rats in the wild vocalize differently than laboratory rats, the team found. For example, lab rats typically emit calls at 22 kilohertz in negative contexts, such as when they sense danger, according to a 2021 review article. By contrast, the city rats used that frequency across more varied scenarios, including while they were foraging. The team posted their results on bioRxiv last month.

“This creature that we see out at night all the time, running around, is actually vocalizing all the while, and we can’t hear it,” Peterson says.

© 2025 Simons Foundation
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