A new joint study by Tel Aviv University (TAU) and Weizmann Institute of Science researchers has yielded an innovative method for bolstering memory processes in the brain during sleep.

The method relies on a memory-evoking scent administered to one nostril. It helps researchers understand how sleep aids memory, and in the future could possibly help to restore memory capabilities following brain injuries, or help treat people with post–traumatic stress disorder (PTSD) for whom memory often serves as a trigger.

The new study was led by Ella Bar, a Ph.D. student at TAU and the Weizmann Institute of Science. Other principal investigators include Prof. Yuval Nir of TAU’s Sackler Faculty of Medicine and Sagol School of Neuroscience, as well as Profs. Yadin Dudai, Noam Sobel and Rony Paz, all of Weizmann’s Department of Neurobiology. It was published in Current Biology on March 5.

Getting plenty of deep, restful sleep is essential for our physical and mental health. Now comes word of yet another way that sleep is good for us: it triggers rhythmic waves of blood and cerebrospinal fluid (CSF) that appear to function much like a washing machine’s rinse cycle, which may help to clear the brain of toxic waste on a regular basis.

The video above uses functional magnetic resonance imaging (fMRI) to take you inside a person’s brain to see this newly discovered rinse cycle in action. First, you see a wave of blood flow (red, yellow) that’s closely tied to an underlying slow-wave of electrical activity (not visible). As the blood recedes, CSF (blue) increases and then drops back again. Then, the cycle—lasting about 20 seconds—starts over again.

The findings, published recently in the journal Science, are the first to suggest that the brain’s well-known ebb and flow of blood and electrical activity during sleep may also trigger cleansing waves of blood and CSF. While the experiments were conducted in healthy adults, further study of this phenomenon may help explain why poor sleep or loss of sleep has previously been associated with the spread of toxic proteins and worsening memory loss in people with Alzheimer’s disease.

“It’s hard to find a body part they can’t regenerate: the limbs, the tail, the spinal cord, the eye, and in some species, the lens, even half of their brain has been shown to regenerate,” Kentucky researcher Randal Voss said in the release.

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“Just a few years ago, no one thought it possible to assemble a 30+GB genome,” said Kentucky biologist Jeramiah Smith. “We have now shown it is possible using a cost effective and accessible method, which opens up the possibility of routinely sequencing other animals with large genomes.”

With that capability, the team hopes to begin probing the full DNA sequence for insights into the axolotl’s regenerative abilities.

“Now that we have access to genomic information, we can really start to probe axolotl gene functions and learn how they are able to regenerate body parts,” said Voss. “Hopefully someday we can translate this information to human therapy, with potential applications for spinal cord injury, stroke, joint repair… the sky’s the limit, really.”

The patients always knew that when he stimulated their arm, it was him doing it, not them. And when they stimulated their arm, they were doing it, not him. So Penfield said, he couldn’t stimulate the will. He could never trick the patients into thinking it was them doing it. He said, the patients always retained a correct sense of agency. They always know if they did it or if he did it.

So he said the will was not something he could stimulate, meaning it was not material.

So he had three lines of evidence: His inability to stimulate intellectual thought, the inability of seizures to cause intellectual thought, and his inability to stimulate the will. … So he concluded that the intellect and the will are not from the brain. Which is precisely what Aristotle said.

We have finally found time cells in the human brain – they help explain how we recall when events happened, and they could be a target for Alzheimer’s therapies.