The conclusion
is that the processing power as previously estimated is hugely larger because
it is going on inside the dendrites as well.
All of which assumes we really know what we are looking at. Of course we are still talking about chemical
signals as yet and no one has figured out how to handle the newly discovered
light signaling also underway.
All this sharply
increases the processing density of the brain sharply to what is possibly
orders of magnitude.
It also makes
the whole problem way more confounding that it appears at first sight.
'Minicomputers'
Live Inside the Human Brain
By By
Charles Q. Choi
The brain may be an even
more powerful computer than before thought — microscopic branches of brain
cells that were once thought to basically serve as mere wiring may actually
behave as minicomputers, researchers say.
The most powerful computer known is the brain. The human brain possesses
about 100 billion neurons with roughly 1 quadrillion — 1 million billion —
connections known as synapses wiring these cells together.
Neurons each act like a relay station for electrical signals. The
heart of each neuron is called the soma — a single thin cablelike fiber known
as the axon that sticks out of the soma carries nerve signals away from the
neuron, while many shorter branches called dendrites that project from the
other end of the soma carry nerve signals to the neuron
Now scientists find dendrites may be more than passive wiring;
in fact, they may actively process information.
"Suddenly, it's as if the processing power of the brain is
much greater than we had originally thought," study lead author Spencer
Smith, a neuroscientist at the University of North Carolina at Chapel Hill,said
in a statement.
Electrical spikes
Axons are what neurons conventionally
use to generate spikes of electricity. However, prior research discovered many
of the same molecules that support electrical spikes are also present in the
dendrites, and experiments with brain tissue showed dendrites can use these
molecules to generate these spikes themselves.
It was unclear whether normal brain activity involved dendritic
spikes, and if so, what role they might play. To find out, Smith and his
colleagues attached tiny glass pipes known as pipettes to dendrites in areas
of the mouse brain responsible
for processing data from the eyes.
"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."
Once they successfully attached pipettes to dendrites, the
researchers took electrical recordings from individual dendrites within the
brains of anesthetized and awake mice. As the mice viewed black-and-white bars
on a computer screen, the scientists detected an unusual pattern of electrical
signals, or bursts of spikes, in the dendrites.
"When we started recording from dendrites, the bursts of
spikes we saw were hard to believe," Smith said. While spikes from axons
"are isolated, solemn obelisks, by comparison, the dendritic spikes we saw
were raucous, dynamic events, with bursts and plateaus."
The properties of electrical signals from the dendrites varied
depending on the features of the images the mice saw. This suggests the
dendrites may actually help the mice process what they see.
Mini computing devices
"This work shows that dendrites, long thought to simply
funnel incoming signals towards the soma, instead play a key role in sorting
and interpreting the enormous barrage of inputs received by the neuron,"
study co-author Michael Hausser at University College Londonsaid in a statement.
"Dendrites thus act as miniature computing devices for detecting and
amplifying specific types of input."
"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."
All in all, "functions we thought required an entire neuron
may be carried out instead by just one portion of a neuron's dendritic
tree," Smith told LiveScience. "This would imply that a single neuron
can act like many, many computational subunits."
However, while he said it was clear dendritic activity increases
the computational power of the brain,
Smith added it was difficult to quantify how much it boosted it by.
The scientists plan to further explore what role dendritic
activity may play elsewhere in the brain other than vision.
"This kind of dendritic processing is likely to be widespread
across many brain areas and indeed many different animal species, including
humans," Hausser said. "This new property of dendrites adds an
important new element to the toolkit for computation in the brain."
Although this is basic research aimed at understanding how brain
circuitry works, it might help address brain disorders as
well, Smith said. "There are diseases that might strongly affect dendritic
spiking and thus brain function, and we can use our new understanding of
dendritic spiking to explore what might go wrong in those diseases," he
said.
The scientists detailed their findings online Oct. 27 in the
journal Nature.
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1 comment:
It does not matter how powerful the human brain is on a hardware level due to religious and political brainwashing/programing the majority of humans have totally defective software...institutionalized stupidity for easy control and exploitation. The really sad part is most humans seem to like being stupid.
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