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The close-ups are so striking, they made the cover of the 11 January Journal of Cell Biology.
To capture this pretty picture, the researchers used a complex technique called electron cryotomography. They first froze rat brain cells in action at temperatures as low as -165 degrees Celsius, then looked at the cells at different angles using an electron microscope and, finally, reconstructed them in three dimensions on a computer.
There are other methods to look at synapses, but they require cells to be fixed in chemicals for a long time, which can distort the final product. Light microscopy, a much older and more popular technique, illuminates living cells, but only down to 400 nanometers.
Electron cryotomography seems to beat all of these: its flash-freezing preserves the cell’s structure, and its resolution is 5 nanometers — the size of a few dozen atoms.
The technique reveals the workings of some of the tiny protein filaments scattered across a synapse, whose role had been largely unknown before. One type of filament, dubbed ‘tethers’, anchors synaptic vesicles — the bubble-like structures that shuttle chemical messengers inside the cell — to the cell membrane. That way, when the cell receives the appropriate electric signal, the vesicles are in the right position to release the chemicals into the synapse.
Simply amazing footage of what a Scottish eagle, Tilly, sees during flight (and an explanation of how the producers captured it):
(Hat tip: Bad Astronomy)
Courtesy: U. of Washington Institute for Learning & Brain Sciences
In typical conversation, people speak at a rate of 250 milliseconds per syllable. So imagine how confusing it would be if you lagged behind — even if only by a fraction of a second.
That tiny delay may be what’s provoking the language problems in some children with autism.
Tim Roberts, a radiologist at the Children’s Hospital of Philadelphia, has been studying the phenomenon for the last decade. He uses magnetoencephalography, or MEG, the ‘hair dryer’ brain imaging method that uses magnetic fields to detect changes in brain activity on the order of 10 milliseconds or less.
Last week, his team reported that when listening to tones of different frequencies, children with autism give brain responses in their right hemispheres about 11 milliseconds slower than healthy controls do. In other, unpublished work, Roberts found a much longer delay — about 50 milliseconds — when children with the disorder process speech sounds, such as ‘ah’ or ‘ou’.
The average age of children in the study was 10 years. If the findings are similar in babies and toddlers with autism, Roberts says this lag measurement may be a reliable marker for diagnosing the disorder, even before other symptoms appear.
MEG would be particularly useful for young children because it’s non-invasive and doesn’t require them to perform a difficult task. On the downside, a MEG scan isn’t a realistic option for the majority of children with autism — there are only about 100 machines worldwide.
I wasn’t a huge fan of the story of Avatar, and I thought it ran about 90 minutes longer than it should have. Nevertheless, I’m sure I’ll remember it for a long time because of the gorgeous visual world of Pandora. Unsurprisingly, the meticulous James Cameron consulted a bona fide biologist to help create Sigourney Weaver’s character, Grace, a no-nonsense botanist, and Pandora’s lush landscape (including, even, a catalog of its flora and fauna, called ‘Pandorapedia‘ to accompany the film).
Saturday’s LA Times ran a fascinating Q&A with said expert, plant physiologist Jodie Holt from the University of California, Riverside. Here’s a cute snippet:
“Overall I thought the science in the movie was fantastic! However, several of my colleagues noted, as I did, that the fact that Grace smoked could be a problem in the lab. The tobacco mosaic virus is common on cigarette tobacco and can easily be transmitted from a smoker’s hands to biological samples and contaminate them. I was never consulted about the smoking, as this was a part of Grace’s character separate from the science. Only biologists in the audience who work with molecular samples would think of this, however.”
Paintings of trees with spindly brown branches and plump green leaves cover the walls. Books, plastic cars and coloring books spill out across the carpeted floor and fill several plastic bins.
The children who come here are as young as 3 months on their first visit, and return every few months to participate in a battery of tests of their social behavior and perceptual processing — the brain’s response to non-social stimuli, such as looking at an ordinary object.
About one in four of these children is particularly interesting to the researchers: They are the younger siblings of children with autism, and are much more likely to develop the disorder than are those without a family history of it. Over the past few years, scientists have gathered heaps of behavioral data from these so-called ‘baby sibs’, but the Baby Lab is among the first to look for distinct signatures of brain activity.
Whole-genome sequencing is truly amazing. If every one of us were decoded tomorrow, scientists would no doubt figure out the cause of a slew of now-mysterious diseases.
The trouble is, doing it right (that is, thoroughly) is pretty expensive: the cheapest option right now is Complete Genomics, which does genome sequencing for $20,000 a pop for institutes willing to buy in bulk.
Researchers are now considering a cheaper option. Rather than sequence the 3 billion basepairs of the entire genome — 99% of which is ‘junk’ DNA — why not focus only on the regions that code for proteins, called exons?
After my fun week in Chicago at the Society for Neuroscience conference, I’m now trying to catch up on tweets and blog posts I missed from the American Society of Human Genetics meeting, in Honolulu.
Nature News’s conference blog has an interesting post reporting one of the first surveys of what kind of people are interested in getting genetic testing — and how their results affect their future health care decisions. The ‘Multiplex Initiative‘ is asking 1,000 healthy adults from a the Henry Ford Health System, in Detroit, whether they’d like to be screened for variants in 15 genes that relate to common diseases, such as diabetes, heart disease, and lung cancer.
From the Nature post, here’s what the researchers are finding so far about which people choose to get the tests (emphasis mine):
…one of the strongest factors that predicts which patients choose to take the multiplex test was how much the patient believed that behavior contributes to overall risk of disease. Those who believed more strongly that behavior contributes to disease – that smoking, not just genetic makeup, affects the risk of lung cancer, for example – were more likely to get tested. McBride’s interpreted this finding to mean that the patients wouldn’t believe that they were powerless to do anything about their disease risk if they got a “high risk” test result. And, conversely, they might be more motivated to change their behavior by a multiplex test result.
And Robert Reid of Group Health Cooperative in Seattle said that patients who took the multiplex test made slightly more visits to their primary care doctors in the 18 months after getting their test results than they had in the 18 months prior to taking the test. But even though the increase was significant, it was still a small increase in sheer number of visits. What’s more, the number of screening tests ordered on the patients didn’t increase after the genetic tests were completed.
That seemed like good news to me. It could mean that these people are actually discussing with their docs what the results could mean, and how their lifestyle could affect their risk…right? Right?!
Wrong. The survey found that only 11 percent of the people who got tested discussed the findings with their docs (and 14 percent planned to discuss them). Reid counted that as good news, indicating that the patients weren’t overreacting and spurring unnecessary (and costly) diagnostic tests. I think that’s overly optimistic.
What’s happening, it seems, is that genetic testing makes people think more about their health (and thus, going to the doctor more). But what good are these extra visits if the docs aren’t being asked to help interpret the results? Do the patients figure that their doctor wouldn’t know much about genetics, anyway? Are they right?
Over at Tech Review’s website, ScienceBlogger Mo Costandi has an amazing photo essay showing how brain imaging technology has progressed since Santiago Ramón y Cajal’s exquisite drawings of the late 19th century. A must-read for brain buffs!
People who lack a corpus callosum (right) have trouble identifying fearful (top) and angry (bottom) faces compared with controls (left). The colors indicate amount of time spent looking at the region, with red being the longest.
People born without the large bundle of nerve fibers that bridges the brain’s hemispheres have trouble identifying fearful faces, and don’t look preferentially at others’ eyes to perform this task, according to research presented Sunday at the Society for Neuroscience meeting in Chicago.
Because similar face-processing patterns are seen in people with autism, the new work bolsters the evolving, 20-year-old theory that autism stems from impaired long-range connections in the brain, says lead investigator Lynn Paul.
The corpus callosum is the largest and fastest conduit in the brain, containing an estimated 250 million axons that connect the language and symbolic reasoning of the left side of the brain with the spatial manipulation, and audio-visual processing generally controlled by the right.
Paul studies agenesis of the corpus callosum (AgCC), a congenital disorder in which this important structure does not develop. About 1 in every 3,000 people are born this way, and many of them have average intelligence, walk and talk normally, and have families.
What these people usually can’t do well is rapidly integrate information between the two sides of the brain, which is particularly important in self-awareness, making social judgments, and carrying out live social interactions. These deficits become most apparent around age 8 or 9, when social interactions become much more complicated.
