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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?!
Oh well, they weren't quick enough!
America, Home of the Brave.
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
..Its (sic) only a matter of time before we can the other 90% of our brain
You go ahead and can yours. I'm keeping mine, thanks.
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.
Also, I'd be interested to see how (or if) they managed to completely wash off antibodies between scans without damaging the tissue or disrupting synaptic structure. Many synaptic proteins recognize and bind each other in the same way that antibodies bind their antigens, so it stands to reason that disrupting antibody binding would also disrupt the binding of these proteins.
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.
RUGBYRUGBYRUGBY
"Now that brain that you gave me. Was it Hans Delbruck's?"
........'No".
--
"Outlook not so good." That magic 8-ball knows everything! I'll ask about Exchange Server next.
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/
:(){
You will end with a situation similar to Star Trek's teleporters. You are killing yourself and hopefully create something elsewhere that believes (for some definition of "believes", maybe behaves is a better approach for that) that is you. And you won't be exactly like before, as with teleporters, to have extra confidence.
In Caprica they were starting to explore the meaning of such thing and then the show got cancelled.
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.
Ah. Good. Uh... would you mind telling me... whose brain... I did put in?
Trust me, you don't want to use "the other 90%" of your brain for consciousness. The full quote is likely to have been something like, "we only use 10% of our brain for consciousness, the rest runs background processes". You do not want to have to consciously keep track of keeping your blood pumping, regulating just the right amount of hormones in each area of the body, heat movement, cellular growth, gamete development, etc. Specialization, even within the body and brain, is important.
I feel fantastic, and I'm still alive.
I do this exact research (diffusion weighted imaging of human brains). We are no where near neuronal/axonal resolution with diffusion weighted scanning (DTI is a special case of diffusion weighted scanning - there are better methods than DTI for analyzing images: e.g., http://brainybehavior.com/neuroimaging/2010/08/hardi_vs_dti/).
With live humans we only resolve down to about 2mm^3. There are many neurons and axons in that space. At best for the whole brain we create only a few fibers for that 2x2x2 mm area when in reality there are tens of thousands to millions of fibers. If we limit our field of view, we can scan at around 500 microns but that is really pushing the limit. With whole removed brains, researchers potentially could scan at 250 microns resolution but 500 microns is more likely. We can do little pieces of brain in ultra high field strength machines at greater resolution (maybe 150 microns).
I think that some day we will get there but we're not particularly close to resolving individual neurons with diffusion weighted imaging.
Further, all neurons have a resting firing rate. They might only fire once per second or so but they are never "still". Most of the neurons in our brain serve as inhibitory regulators for other neurons. If this wasn't the case, we'd have too much activity.
The pasta. You mean wake up and smell the pasta.
The glorious smell of divine carbohydrates smothered in both marinara AND red sauce, nestling two bountiful orbs of meat and bread conglomerate.
Ramen brother, ramen.