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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.
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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