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New Imaging Method Reveals Brain Connections
An anonymous reader writes "Researchers at the Stanford University School of Medicine, applying a state-of-the-art imaging system to brain-tissue samples from mice, have been able to quickly and accurately locate and count the myriad connections between nerve cells in unprecedented detail, as well as to capture and catalog those connections' surprising variety. A typical healthy human brain contains about 200 billion nerve cells, or neurons, linked to one another via hundreds of trillions of tiny contacts called synapses. It is at these synapses that an electrical impulse traveling along one neuron is relayed to another, either enhancing or inhibiting the likelihood that the second nerve will fire an impulse of its own. One neuron may make as many as tens of thousands of synaptic contacts with other neurons, said Stephen Smith, PhD, professor of molecular and cellular physiology and senior author of a paper describing the study, to be published Nov. 18 in Neuron."
So they have this wonderful new imaging method that can show something unseen until now... and they have no pictures with the article.
Seriously?!
A slab of tissue — in this case, from a mouse's cerebral cortex — was carefully sliced into sections only 70 nanometers thick. (That's the distance spanned by 700 hydrogen atoms theoretically lined up side by side.) These ultrathin sections were stained with antibodies designed to match 17 different synapse-associated proteins, and they were further modified by conjugation to molecules that respond to light by glowing in different colors.
In case you were wondering, you have to be dead to be scanned with this technique, and it doesn't look like they will be able to press a button and scan a whole brain.
http://michaelsmith.id.au
This is immunohistochemistry, just scaled up to many different antibodies for the same sample and realigned in space.
Also, the connectivity is lost. You can't tell which neurons are connected to which other neurons. The overall circuitry, essential for the functioning of neural networks, is invisible. All you can see is points of contact between neurons.
Perhaps combining this technique with super high resolution diffusion tensor imaging would be a way forward. Although, as far as I know, DTI is nowhere near neuron or axon resolution as of yet.
We are already using the 100% of our brain. For something as expensive to maintain as the brain, having 90% of unused area is an evolutionary disadvantage. Maybe we could give it a better use, for some value of better, but is not unused right now.
From the CNET article:
They found that the brain's complexity is beyond anything they'd imagined, almost to the point of being beyond belief, says Stephen Smith, a professor of molecular and cellular physiology and senior author of the paper describing the study: "One synapse, by itself, is more like a microprocessor--with both memory-storage and information-processing elements--than a mere on/off switch. In fact, one synapse may contain on the order of 1,000 molecular-scale switches. A single human brain has more switches than all the computers and routers and Internet connections on Earth.
This is why I am extremely skeptical of claims that we will be able to effectively model the brain, or recreate it artificially, any time soon.
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I was just about to come here and mention DTI, but you beat me to it.
I'm not sure if they're down to neuron/axon resolution yet, but I do know they're pretty close. Dr. Walter Schneider at the University of Pittsburgh has created a movie image of the various connections in his brain.
http://www.lrdc.pitt.edu/schneider/
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Depends on the definition of "use." If you mean firing all at once, then yes, epileptics have that issue. However, just because a neuron is not firing does not mean that it is not doing something and/or receiving signals. BTW neurons don't just receive signals from other neurons, they receive signals from other tissue in the form of hormones.