Wednesday, July 26, 2017


My people are destroyed for lack of knowledge: because thou hast rejected knowledge, I will also reject thee, that thou shalt be no priest to me: seeing thou hast forgotten the law of thy God, I will also forget thy children

Hosea 4:6

By  Elizabeth Armstrong Moore | Cnet | Nov. 17, 2010

The human brain is truly awesome.

A typical, healthy one houses some 200 billion nerve cells, which are connected to one another via hundreds of trillions of synapses. Each synapse functions like a microprocessor, and tens of thousands of them can connect a single neuron to other nerve cells. In the cerebral cortex alone, there are roughly 125 trillion synapses, which is about how many stars fill 1,500 Milky Way galaxies.

This is a visual reconstruction from array-tomography data of synapses in the mouse somatosensory cortex, which is responsive to whisker stimulation.

(Credit: Stephen Smith/Stanford)

These synapses are, of course, so tiny (less than a thousandth of a millimeter in diameter) that humans haven't been able to see with great clarity what exactly they do and how, beyond knowing that their numbers vary over time. That is until now.

Researchers at the Stanford University School of Medicine have spent the past few years engineering a new imaging model, which they call array tomography, in conjunction with novel computational software, to stitch together image slices into a three-dimensional image that can be rotated, penetrated and navigated. Their work appears in the journal Neuron this week.

To test their model, the team took tissue samples from a mouse whose brain had been bioengineered to make larger neurons in the cerebral cortex express a fluorescent protein (found in jellyfish), making them glow yellow-green. Because of this glow, the researchers were able to see synapses against the background of neurons.

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:

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