(Press-News.org) CAMBRIDGE, Mass. -- As anyone who as ever picked up a guitar or a tennis racket knows, precise timing is often an essential part of performing complex tasks. Now, by studying the brain circuits that control bird song, MIT researchers have identified a "chain reaction" of brain activity that appears to control the timing of song.
The song of the zebra finch is very stereotypic; each song lasts about 1 second, and consists of multiple syllables whose timing is almost precisely the same from one performance to the next. "It's a great model system for studying how the brain controls actions", says Michale Fee, senior author of the study and a member of the McGovern Institute for Brain Research.
The brain structures involved in bird song production have been identified, and Fee and colleagues had previously shown that the tempo of the song is controlled by a brain area known as HVC. During the 1-second song, individual neurons in HVC fire just one short burst of activity at a precise time point within the song. Different neurons fire at different times, so the activity of these neurons represents a 'time stamp' that causes the correct instructions to be sent to the vocal organs at each instant within the song.
But how does each HVC neuron know when to fire with such perfect timing? Several different ideas have been proposed, but one especially appealing idea is the "synfire chain" model, in which neurons fire in a chain reaction – each one triggering the next in the sequence, like a cascade of falling dominos.
In a new study, which appears in the October 24 online issue of Nature, Fee and colleagues have now tested this idea using intracellular recordings, an approach that can record tiny voltage fluctuations in individual HVC neurons. In a technical tour-de-force, they developed a method in which these recordings could be made while the bird was freely moving around his cage and engage in natural behaviors such as singing.
Their results support the chain of dominoes model. When individual HVC neurons fire, they do so suddenly, as if hit by the preceding domino. There was no prior build-up of activity; instead, each neuron remained silent until its turn came to fire, at which point it showed a sudden burst of activity, presumably caused by excitatory input from the previous neuron in the chain. In further experiments, the authors showed that this burst of activity is triggered suddenly by an all-or-none influx of calcium through specialized membrane channels that open in response to this excitatory input.
The MIT researchers also showed that the timing of neural bursts in HVC neurons is not easily disturbed by small electrical perturbations. That's important, explains first author Michael Long, who is now at New York University's Langone Medical Center. "If one neuron made a mistake in its timing, every subsequent neuron down the chain would also be off. It would be like a musician with no sense of rhythm."
"This is the first time we've been able to understand the generation of a learned behavioral sequence", says Fee. "We predict that similar mechanisms probably exist in other brains, including our own."
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Dezhe Jin of Pennsylvania State University also contributed to the study.
Source: "Support for a synaptic chain model of neuronal sequence generation," Long MA, Jin DZ, Fee MS. Nature. 24 Oct 2010.
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Producing tightly focused beams of high energy X-rays, to examine everything from molecular structures to the integrity of aircraft wings, could become simpler and cheaper according to new research.
Today, in Nature Physics, researchers from Imperial College London, the University of Michigan and Instituto Superior Téchnico Lisbon describe a tabletop instrument that produces synchrotron X-rays, whose energy and quality rivals that produced by some of the largest X-ray facilities in the world.
Scientific and medical advances often depend on the development of better ...
The manuscripts associated with these summary presentations are in press and will be published in the Canadian Cardiovascular Society (CCS) journal in 2011.
Guidelines are one of the highest priorities for the CCS.
"Feedback and surveys from the CCS membership and the broader cardiovascular community tell us that CCS guidelines are among our most important functions," says CCS president Dr. Charles Kerr. "As we embark on each new guideline project, we endeavor to identify strong co-chairs and expert panels so we can continue to support Canadian cardiovascular health ...
A team of researchers and runners from the Heart and Stroke Foundation have come up with a practical way of answering the question. They used data from magnetic resonance imaging (MRI) to find out what is really going on in the marathoner's heart as the kilometers pile up.
"Marathon runners can be a lot less fit than they think," Dr. Eric Larose today told the Canadian Cardiovascular Congress 2010, co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society.
Lack of real aerobic fitness may directly impact the ways the heart organizes itself ...
Montreal – The blood vessels of obese children have stiffness normally seen in much older adults with cardiovascular disease, Dr. Kevin Harris today told the Canadian Cardiovascular Congress 2010, co-hosted by the Canadian Cardiovascular Society and the Heart and Stroke Foundation. The clock is ticking and the shape of the 13 year-old-heart is changing – for the worse.
"We were surprised to find that these obese children already have stiff blood vessels," says Dr. Harris from B.C. Children's Hospital. "Aortic stiffness is an early indicator of cardiovascular disease in ...
"These two high-risk but universally undertreated groups are less likely attend cardiac rehab than their younger, male counterparts even when they are referred," says Dr. Martin, PhD(c) and surgical trainee at University Calgary/Libin Cardiovascular Institute, speaking on behalf of her co-authors at the Cardiac Wellness institute of Calgary and APPROACH. "And when women do attend cardiac rehab, they tend to present later and at a more serious stage of the disease."
The study of 6,000 people living with cardiovascular disease found that participation in cardiac rehab was ...
FOR EMBARGOED RELEASE:
October 25, 2010 12:01AM ET
New Way of Expanding Cancer Screening for Minority Women
New York, October 25, 2010 — Minority patients have a significantly decreased survival from colon cancer compared to white patients, most often as a result of a late diagnosis. To help address this problem, a team of healthcare professionals at Memorial Sloan-Kettering Cancer Center has identified an efficient way to increase minority access to lifesaving colorectal cancer screening (CRCS) in communities where multiple barriers ...
Offering colorectal cancer screening to poor minority women during mammography visits can effectively expand screening in this otherwise underserved population, although lack of medical insurance remains a significant barrier. That is the conclusion of a new study published early online in Cancer, a peer-reviewed journal of the American Cancer Society. The results highlight the need to find alternative funding sources for colorectal cancer screening from the government or private institutions.
Colorectal cancer screening is inadequate in minority communities in the United ...
Montreal − Levels of anxiety sensitivity may be important in choosing medical treatment for patients with heart failure and atrial fibrillation (AF), Montreal Heart Institute researchers today told the Canadian Cardiovascular Congress 2010, co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society.
Heart and Stroke Foundation researcher and lead author Nancy Frasure-Smith, PhD explained that anxiety sensitivity is the degree to which a person is frightened by bodily sensations and symptoms, particularly those associated with anxiety. ...
For Immediate Release – October 25, 2010 – (Toronto) –A new study from The Centre for Addiction and Mental Health (CAMH) found that contraband tobacco accounts for 43% of all cigarettes consumed by Ontario high school daily smokers in grades 9 to 12.
The study, published in the current edition of Tobacco Control, looked at the smoking habits of Ontario students and found that of high school daily smokers, 50% smoked at least one contraband cigarette per day over the last year. Contraband cigarettes are manufactured on and smuggled from US and Canadian native reserves ...
PERI Software, based in Newark, NJ plans to show its latest smart grid technology software and hardware products at the National Minority Supplier Development Council (NMSDC) Conference. The four-day Conference and Business Opportunity Fair — the nation's benchmark forum on minority supplier development - takes place at the Miami Beach Convention Center beginning Sunday, October 24th and runs through Wed., Oct. 27, 2010.
"As the nation's leading Asian-owned global business solutions company, we're delighted to display our smart grid technology and electric, gas and ...