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Stanford University researchers developed a process to make a mouse brain totally transparent. The brain has to be, er, removed from the mouse first but it's still an amazing process that enables scientists to see the entire brain in great detail, without chopping it up. Brilliant bioengineer, Karl Deisseroth, a pioneer in the field of optogenetics, postdoc Kwanghun Chung, and their colleagues have used the same technique, called CLARITY, to make fish and, yes, bits of human brains transparent as well. The process involves replacing the fatty molecules, called lipids, with a hydrogel. As a result, the brain can be studied with visible light and chemical markers with unprecedented clarity and resolution. Check out the stunning fly-through of the rodent's brain above.
Scientists are amassing evidence that suggests exposure to tetraethyl lead — the additive once used in almost all the gasoline sold in the United States — could account for the dramatic increase in crime that happened in this country between the 1960s and 1980s. As leaded gasoline was phased out, they say, children were exposed to less lead, leading to the decline in crime that began to really kick in in the 1990s.
This is the same curve of crime statistics that economist Steven Levitt, of Freakonomics fame, attributed to the legalization of abortion. Levitt's theory was that, after Roe v. Wade, there were fewer unwanted babies born into dire circumstances and, thus, fewer people to grow up on the path to criminal behavior. Levitt matched the rise in abortion rates to the decrease in crime, but frankly, there are a lot of things that you can correlate to the decrease in crime.
What makes the lead theory interesting is that correlations match not just at the national level, but at regional, and even neighborhood levels. Increases in lead relate to increases in crime — usually a couple of decades later. Likewise decreases in lead relate to later decreases in crime. What's more the same correlations exist in countries all over the world. Meanwhile, we know that lead has big impacts on growing bodies — it affects brain function, it's linked to hyperactivity, difficulty managing aggression, and lowered IQ.
Correlation isn't causation. But in this case they definitely seem to be winking suggestively at one another. Kevin Drum has an excellent piece on this at Mother Jones, working through a decade worth of research by multiple scientists that supports this disturbing conclusion. It really is possible that we, as a society, damaged a generation of children and caused a crime wave (not to mention the ongoing damage to kids that live in high-lead neighborhoods today).
Via Michael Mechanic
This is kind of neat. Scientists conducted several psychological and neuro-imaging tests on Temple Grandin — the woman who has used her own autism as a model for designing better livestock control systems. What they found is that Grandin's brain looks different, structurally, from that of a neuro-typical person.
Grandin’s brain volume is significantly larger than that of three neurotypical controls matched on age, sex and handedness. Grandin’s lateral ventricles, the chambers that hold cerebrospinal fluid, are skewed in size so that the left one is much larger than the right. “It’s quite striking,” Cooperrider says. On both sides of her brain, Grandin has an abnormally large amygdala, a deep brain region that processes emotion. Her brain also shows differences in white matter, the bundles of nerve fibers that connect one region to another. The volume of white matter on the left side of her brain is higher than that in controls, the study found.
Grandin isn't the only person with autism to have had their brain scanned. But the differences that have been found aren't always consistent from one study to another. That, of course, makes some sense, given the fact that the word "autism" encompasses a whole spectrum of differences and disabilities which may or may not represent one single thing. But there have been several studies that did find differences similar to the ones found in Temple Grandin.
And here's the really interesting thing. Some scientists think that the common differences we do keep seeing — especially the bit about the larger brain volume — might be a clue that what eventually becomes autism actually begins in the womb. Here's a quick excerpt from a story that Carl Zimmer wrote about this stuff last spring:
When autistic children are born, Courchesne’s research suggests, they have an abundance of neurons jammed into an average-size brain. Over the first few years, the neurons get bigger and sprout thousands of branches to join other neurons. The extra neurons in the autistic brain probably send out a vast number of extra connections to other neurons. This overwiring may interfere with normal development of language and social behavior in young children. It would also explain the excess brain size seen in the MRI scans.
Special thanks to GrrlScientist!
I had no idea that neurons came in such a beautiful diversity of shapes. Each of these neurons has a different function, too: A. Purkinje cell B. Granule cell C. Motor neuron D. Tripolar neuron E. Pyramidal Cell F. Chandelier cell G. Spindle neuron H. Stellate cell.
The image, drawn by science journalist Ferris Jabr, comes from a post of his on the Brainwaves blog, explaining the discovery of the neuron—and the first realizations that not all neurons looked the same. It's the first part of a new series he's working on called "Know Your Neuron".
When the leading anatomists of the 19th century examined fragile nervous tissue with the best microscopes available to them, they identified cell bodies that sprouted many tangled projections. German histologist Joseph Gerlach’s observations convinced him that the fibers emerging from different cell bodies fused to form a continuous network, a seamless web known as the “reticulum.” His ideas were popular. Many researchers accepted that, unlike the heart or liver, the brain and nervous system could not be split up into distinct structural units.
In 1873, Italian physician Camillo Golgi discovered a chemical reaction that allowed him to examine nervous tissue in much greater detail than ever before. For some reason, hardening a piece of brain in potassium dichromate, and subsequently dousing it with silver nitrate, dyed only a few cell bodies and their respective projections in the tissue sample, revealing their complete structures and exact arrangement within the unstained tissue. If the reaction had stained all the neurons in a sample, Golgi would have been left with an unfathomable black blotch, as though someone had spilled a bottle of ink. Instead, his technique yielded neat black silhouettes against a translucent yellow background.
Read the rest of Know Your Neuron: The Discovery and Naming of the Neuron
I love serendipity. On the same day that Anja Austerman posted this awesome knit hat to my Google+ feed, Kevin Zelnio also posted a link reminding me of the existence of the The Museum of Scientifically Accurate Fabric Brain Art. Xeni posted about the museum here back in 2008. But it's awfully fun to contrast the super-detailed brain art on display there with this more whimsical variety.