The human brain is truly awesome.Here's a four minute video showing the mouse brain as revealed by the Array Tomography. Those synapses are the little orange-red dots in the tissue. Keep in mind that this unimaginably complex organ is the product merely of random mutations and natural selection. In other words, it's an accident. If you believe otherwise, then you're just a superstitious ninny with silly blind faith in a supernatural "sky god." Sophisticated people know that this sort of complexity can easily arise by chance.
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.
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: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.
Just don't ask them to explain how.
