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A beautiful, synapse-by-synapse tour of a brain

National Geographic has a nice video (as well as a long story by Carl Zimmer) about scientists who are trying to learn more about the way the brain works by slicing mice brains into incredibly thin sections, fore to aft, and then using scans of those slices to create what amounts to a wiring diagram. The goal is to see how all the parts connect and, hopefully, get a better idea of how they all work together.

The video is lovely, with some great shots of lab work and an animated tour of the mouse brain slices. The animation looks, at first, like a time-lapse thing, but it's actually more like driving down a highway and watching buildings on the roadside appearing, becoming larger, and then shrinking in the rearview. Really great stuff! It also underlines a bit why I'm pretty skeptical of Ray Kurzweil's singularity. Or, at least, his estimations of how long it will take for scientists to understand our brains well enough that they could be replicated digitally.

Video Link

Man busted for stealing and selling brains from medical museum

InimanstealsbrainsDavid Charles, 21, was arrested for allegedly stealing jars of brain tissue from the Indiana Medical History Museum. Police tracked Charles down after a California fellow purchased the jars for $100 each on eBay. Museum director Mary Ellen Hennessey Nottage spoke to the man who bought the brains. "He just said he liked to collect odd things," Nottage said.

"Police: Man stole brains, sold them on eBay" (Indianapolis Star)

Musical mind-reading experiment

Researchers at the University of Washington scanned the brains of volunteers listening to one of several simple songs. Based on the neural activity they saw, the scientists were able to identify what song the subjects were hearing. Psychology professor Geoff Boynton presented the results of their study at this week's Neuroscience 2013 conference. (via New Scientist) David 4

The science of "new baby smell"

TIL: There are studies that suggest new babies really do smell different, and seem to trigger special brain chemical pathways in women. But, simultaneously, the smells we more consciously associate with "new baby" — i.e., the new baby smell used in baby products and baby-fresh scents — varies widely by culture. Make of this what you will. Maggie 15

Do IQ test results mean anything at all?

The answer is yes — but only in certain circumstances and that "yes" comes with a whole bunch of caveats. At Discover, Emily Sohn has a nice basic primer on what we know now about intelligence testing and what your score on an IQ test does and doesn't mean. Maggie 12

What is dopamine?

Dopamine — the most talked-about human neurotransmitter — isn't a "love drug", or a "lust drug", or an "addiction drug", writes Bethany Brookshire in a smarter-than-average neuroscience story at Slate. It's actually a lot more complicated than that, and if you keep trying to pigeonhole and oversimplify what it does, you're going to completely misunderstand how your brain works. Maggie 6

What's it like to be a small bird?

Brandon Keim has an amazing feature up at Aeon Magazine, about the idea of animal consciousness — i.e., how animals think and feel and experience their own lives. After delving into the chimpanzee experience of death for a couple weeks, this story really grabbed my attention. Increasingly, it's an idea that scientists are paying more attention to, as well. Maggie 4

What neuroscientists think of the BRAIN Initiative

In general, they seem to like it. But with reservations. The Obama Administration's highly touted brain-mapping program — pitched as a neurological analog to the Human Genome Project — might be approaching the problem of how the brain works in the wrong way. In particular, if the Initiative only focuses on mapping activity in the brain, it's going to miss out on the ways activity and neural architecture work together to create a functioning system. Maggie

Making brains transparent

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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.

"Getting CLARITY: Hydrogel process developed at Stanford creates transparent brain"

Rat brains linked in first ever brain-to-brain interface

"Scientists have connected the brains of lab rats, allowing one to communicate directly to another via cables. The wired brain implants allowed sensory and motor signals to be sent from one rat to another, creating the first ever brain-to-brain interface." [Jen Whyntie at the BBC] Rob

Leaded gasoline and the 20th-century crime wave

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

Temple Grandin's brain doesn't just think differently, it is physically different

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.

Read the story about Temple Grandin's brain

Read Carl Zimmer's story on structural differences in brains of people with autism

Special thanks to GrrlScientist!

Image: Photograph by Jonathunder for Wikipedia, used under CC license.

The beautiful shapes of neurons

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

Fabric brain art

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.