On 28 Oct 2013, at 19:20, spudboy...@aol.com wrote:

I read, somewhere, Professor Marchal, that it was the "spindle cells" in the brain that pushed the smarter creatures on this planet into high gear, so to speak, not so much glial, unless we are describing the same thing, primates, whales, dolphins, have spindle cells, and why this makes a difference I don't know. For no rational reason, my limbic system is urging me (?) to include in this email, the first stanza from Hyperactive, by Thomas Dolby. It adds nothing to this discussion, yet here it is, because it seems somehow, fitting.

Spindle neurons seems to be special highways to me. Glial cells seems to play some role in chronic pain. Anyway, this bears on the substitution level, which we cannot know. The pioneer of immortality will bet on artificial mechanism which they can afford, and will not survive without some defects.





At the tender age of three
I was hooked to a machine
Just to keep my mouth from spouting junk
Must have took me for a fool
When they chucked me out of school
'Cause the teacher knew I had the funk

:)

Bruno




-----Original Message-----
From: Bruno Marchal <marc...@ulb.ac.be>
To: everything-list <everything-list@googlegroups.com>
Sent: Mon, Oct 28, 2013 1:53 pm
Subject: Re: Neuroscientists discover new 'mini-neural computer' in the brain


On 28 Oct 2013, at 16:52, Craig Weinberg wrote:

http://medicalxpress.com/news/2013-10-neuroscientists-mini-neural-brain.html

Dendrites, the branch-like projections of neurons, were once thought to be passive wiring in the brain. But now researchers at the University of North Carolina at Chapel Hill have shown that these dendrites do more than relay information from one neuron to the next. They actively process information, multiplying the brain's computing power.

"Suddenly, it's as if the processing power of the brain is much greater than we had originally thought," said Spencer Smith, PhD, an assistant professor in the UNC School of Medicine.

His team's findings, published October 27 in the journal Nature, could change the way scientists think about long-standing scientific models of how neural circuitry functions in the brain, while also helping researchers better understand neurological disorders.

"Imagine you're reverse engineering a piece of alien technology, and what you thought was simple wiring turns out to be transistors that compute information," Smith said. "That's what this finding is like. The implications are exciting to think about."

Axons are where neurons conventionally generate electrical spikes, but many of the same molecules that support axonal spikes are also present in the dendrites. Previous research using dissected brain tissue had demonstrated that dendrites can use those molecules to generate electrical spikes themselves, but it was unclear whether normal brain activity involved those dendritic spikes. For example, could dendritic spikes be involved in how we see?

The answer, Smith's team found, is yes. Dendrites effectively act as mini-neural computers, actively processing neuronal input signals themselves.

Directly demonstrating this required a series of intricate experiments that took years and spanned two continents, beginning in senior author Michael Hausser's lab at University College London, and being completed after Smith and Ikuko Smith, PhD, DVM, set up their own lab at the University of North Carolina. They used patch-clamp electrophysiology to attach a microscopic glass pipette electrode, filled with a physiological solution, to a neuronal dendrite in the brain of a mouse. The idea was to directly "listen" in on the electrical signaling process.

"Attaching the pipette to a dendrite is tremendously technically challenging," Smith said. "You can't approach the dendrite from any direction. And you can't see the dendrite. So you have to do this blind. It's like fishing if all you can see is the electrical trace of a fish." And you can't use bait. "You just go for it and see if you can hit a dendrite," he said. "Most of the time you can't."

Once the pipette was attached to a dendrite, Smith's team took electrical recordings from individual dendrites within the brains of anesthetized and awake mice. As the mice viewed visual stimuli on a computer screen, the researchers saw an unusual pattern of electrical signals – bursts of spikes – in the dendrite.

Smith's team then found that the dendritic spikes occurred selectively, depending on the visual stimulus, indicating that the dendrites processed information about what the animal was seeing.

To provide visual evidence of their finding, Smith's team filled neurons with calcium dye, which provided an optical readout of spiking. This revealed that dendrites fired spikes while other parts of the neuron did not, meaning that the spikes were the result of local processing within the dendrites.

Study co-author Tiago Branco, PhD, created a biophysical, mathematical model of neurons and found that known mechanisms could support the dendritic spiking recorded electrically, further validating the interpretation of the data.

"All the data pointed to the same conclusion," Smith said. "The dendrites are not passive integrators of sensory-driven input; they seem to be a computational unit as well."

His team plans to explore what this newly discovered dendritic role may play in brain circuitry and particularly in conditions like Timothy syndrome, in which the integration of dendritic signals may go awry.


"This revealed that dendrites fired spikes while other parts of the neuron did not, meaning that the spikes were the result of local processing within the dendrites."

Yep, looks like neurons have a nervous system of their own now. Still think that consciousness is a product of the brain?

I refer you to my rare posts where I suggest that the level is the molecular level, and should include the glial cells, which in my opinion (from diverse reading) handle to information.

I also defend the idea that an amoeba, by being unicellular, can be seen as a cell being simultaneously a digestive cell, a muscular cells, a liver cell, a kidney cell, a bone cell, and a brain cell.

Amoebas are not completely stupid and deserve respects, and so are any each of our own cells, despite those cells in multicellular organism have lost a bit of their freedom and universality to cooperate in what is ourself.

Again, the bold quote illustrates comp, and the fact that the level is lower than some thought.

Also with comp, consciousness is NOT a product of the mind. that's still too much an aristotelian way to express the "identity" thesis. Consciousness is not physical, it is the mental state of person associated to machines, when those person develop *some* true belief.

Bruno


http://iridia.ulb.ac.be/~marchal/



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