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Category: neuroscience – Page 740

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.

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“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.

“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.”

Continue reading “Scientists: Salamander DNA Could Regenerate Human Body Parts” | >

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.

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An international team of researchers that pooled genetic samples from developmentally disabled patients from around the world has identified dozens of new mutations in a single gene that appears to be critical for brain development.

“This is important because there are a handful of that are recognized as ‘hot spots’ for causing ,” said lead author Debra Silver, an associate professor of molecular genetics and microbiology in the Duke School of Medicine. “This gene, DDX3X, is going to be added to that list now.”

An analysis led by the Elliott Sherr lab at the University of California-San Francisco found that half of the DDX3X mutations in the 107 children studied caused a loss of function that made the gene stop working altogether, but the other half caused changes predicted to disrupt the function of the gene.

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In a recent study, scientists at Baycrest’s Rotman Research Institute (RRI) found that research participants moved their eyes to determine whether they had seen an image before, and that their eye movement patterns could predict mistakes in memory. They obtained these results using an innovative new eye tracking technique they developed.

“Our findings indicate that eye movements play a functional role in retrieval,” says Dr. Jennifer Ryan, senior scientist at the RRI and Canada Research Chair in Cognitive Neuroscience of Memory. “They can tell us a lot about someone’s memory.”

This study builds on previous Baycrest research examining the link between eye movements and memory, including the role of our eye movements in memorization and the weakening connection between our eye movements and our brain activity as we age.

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My most recent post, “Living in a Computer Simulation,” elicited some insightful comments from a reader skeptical of the possibility of mind uploading. Here is his argument with my own brief response to it below.

My comment concerns a reductive physicalist theory of the mind, which is the view that all mental states and properties of the mind will eventually be explained by scientific accounts of physiological processes and states … Basically, my argument is that for this view of the mind, mind uploading into a computer is completely impractical due to accumulation of errors.

In order to replicate the functioning of a “specific” human mind within a computer, one needs to replicate the functioning of all parts of that specific brain within the computer. [In fact, the whole human body needs to be represented because the mind is a product of all sensations of all parts of the body coalescing within the brain. But, for the sake of argument, let’s just consider replicating only the brain.] In order to represent a specific human brain in the computer, each neuron in the brain would need a digital or analog representation, instantiated in hardware, software or a combination of the two. Unless this representation is an exact biological copy (clone), it will have some inherent “error” associated with it. So, let’s do a sort of “error analysis” (admittedly non-rigorous).

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Researchers in Europe and the UK have managed to connect biological and artificial neurons together – and allow them to communicate long distances through the internet. The biological neurons were grown in one country, sent signals through an artificial synapse located in another to electronic neurons in a third country.

As advanced as supercomputers get, the human brain still utterly leaves them in the dust. It’s made up of neurons that communicate with each other through pulses of electrical signals, passed across tiny gaps known as synapses. These neurons can both process and store information, unlike computers that require separate types of memory for each task.

Artificial versions of neurons and synapses have shown to be far more powerful than traditional computer chip designs, but they’re still in the experimental stage. And now, a team of researchers has taken the next step and connected the artificial and biological versions between three different countries.

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