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Hebbs Rule Shown: Researchers have for the first time directly created and destroyed neural connections

Hebbs Rule Shown: Researchers have for the first time directly created and destroyed neural connections | sciences I 3> | Scoop.it

Researchers from UCSD have for the first time directly created and destroyed neural connections that connect high level sensory input and high level behavioral responses. 

 

Donald Hebb in 1949 was one of the first to seize upon this observation.  He proposed that on the biological level, neurons were rewired so that coordinated inputs and outputs get wired together.  As such, were there a nausea neuron and a boat neuron, through the effects of association, the two would get wired together so that the “boat” itself fires up pathways in the “nausea” part of the brain.

 

In the field of neural networks, this has a name: Hebbian learning.  Pavlov of course also described this phenomenon, and tested it in animals, bequeathing its name the “conditioned response”.

 

Until now the wiring of neural inputs and outputs was a theory with good but indirect evidence.  At UCSD, neuroscientists teamed up with molecular biologists to engineer a mouse whose neurons can be directly controlled for forming and losing connections.

 

They did this by injecting an engineered virus into the auditory nerve cells.  The viruses, largely harmless, carry a light responsive molecular switch (a membrane protein “channel” actually) which gets inserted into cells of the auditory region.  Using laser light of certain frequencies it is possible to both “potentiate” or “depress” the auditory nerve cells.

 

The upshot is that the researchers could directly make the auditory nerve cells increase or decrease their signal strength to other nerve cells, without needing a real, external noise.  In effect, they’ve short-circuited the noise input.  In experiments, they used a light electrical pulse to shock mice while simultaneously stimulating the auditory input with the laser-activated switch.

 

Basically they flashed the laser light at the ear of the mouse.  Over time, the mouse began to associate the laser pulse induced nerve signal with the electrical shock.  The mice were conditioned to exhibit fear even when there was no shock.

 

The crux of the experiment is what happened when the scientists flashed the laser in a way to weaken the auditory nerve.  Now the mouse stopped responding in fear to the laser auditory stimulus.

The experiments showed for the first time that associative learning was indeed the wiring together of sensory and response neurons.  The study was published in Nature.

 

Nature (2014) doi:10.1038/nature13294


Via Dr. Stefan Gruenwald
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Harvard researchers discover hormon that spurs beta cell production. Monthly alternative to insulin?

Harvard researchers discover hormon that spurs beta cell production. Monthly alternative to insulin? | sciences I 3> | Scoop.it

Researchers at the Harvard Stem Cell Institute have discovered a hormone that holds promise for a dramatically more effective treatment of type 2 diabetes, a metabolic illness afflicting an estimated 26 million Americans. It could eventually mean that instead of taking insulin injections three times a day, you might take an injection of this hormone once a week or once a month, or in the best case maybe even once a year,” said Doug Melton (right). Melton and postdoctoral fellow Peng Yi discovered the hormone betatrophin, which has the potential to improve diabetes treatment.

 

Researchers at the Harvard Stem Cell Institute (HSCI) have discovered a hormone that holds promise for a dramatically more effective treatment of type 2 diabetes, a metabolic illness afflicting an estimated 26 million Americans. The researchers believe that the hormone might also have a role in treating type 1, or juvenile, diabetes.

 

The hormone, called betatrophin, causes mice to produce insulin-secreting pancreatic beta cells at up to 30 times the normal rate. The new beta cells only produce insulin when called for by the body, offering the potential for the natural regulation of insulin and a great reduction in the complications associated with diabetes, the leading medical cause of amputations and non-genetic loss of vision.

 

The researchers who discovered betatrophin, HSCI co-director Doug Meltonand postdoctoral fellow Peng Yi, caution that much work remains to be done before it could be used as a treatment in humans. But the results of their work, which was supported in large part by a federal research grant, already have attracted the attention of drug manufacturers.


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Biosciencia's curator insight, April 28, 2013 7:10 AM

The work was published today by the journal Cell as an early online release.

CAEXI BEST's curator insight, April 28, 2013 7:34 PM
Les chercheurs de Harvard viennent de  découvrir une hormone qui stimule la production de cellules bêta. Remplacement mensuel à l'insuline?
Center for Accessible Living NKY's curator insight, May 6, 2013 12:28 AM

More on the new possible treatment for juvenile diabetes.

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C’est tellement compliqué on ne peut jamais savoir ! Pas de vaccins, pas d’OGM et pas de jus de tomate !

C’est tellement compliqué on ne peut jamais savoir ! Pas de vaccins, pas d’OGM et pas de jus de tomate ! | sciences I 3> | Scoop.it
Le principe de précaution dans sa forme rationnelle est une réaction qui me paraît tout-à-fait sensée face à un techno-optimisme béat (qui n’a guère plus cours depuis un très bon moment quand même je pense) et face à de potentielles élites ne se préoccupant...

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Samsung's Galaxy S IV Smartphone Could Have Eye Scrolling

Samsung's Galaxy S IV Smartphone Could Have Eye Scrolling | sciences I 3> | Scoop.it

Samsung's next generation smartphone -- the Galaxy S IV -- could include an eye scrolling feature, making it easier for users to read text, hands free.


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Starlight spectra may reveal signature of life

Starlight spectra may reveal signature of life | sciences I 3> | Scoop.it

Light spectrum from the atmospheres of two Earth-like planets could provide evidence of life, writes Rowan Philp. Two planets as friendly to life as the Earth have been found. Now, Harvard astronomers have told the Mail & Guardian that confirming the existence of life out there is just a matter of time, using an ingenious trick with starlight.

 

Just Google "solar spectrum", and you will see what "sunshine" really looks like under the proverbial microscope. The pair of dark shadows you will see in the burnt-yellow section of its rainbow, reflecting its strong sodium content, is our Sun's unique calling card.

 

The initial question for Kaltenegger and other astrobiologists was this: What would happen if that same bolt of light also passed through the atmosphere of an alien planet as it passed in front of its star before reaching our telescopes? Answer: More rainbow shadow lines. If she can find spectral lines for oxygen and methane, which a parent star itself does not have, she will have made a discovery on the scale of Hubble or Galileo.

 

Roughly 1000 extrasolar planets have so far been confirmed, but the vast majority are way too big or too hot for life to have a chance.

 

Until recently, the "signatures for life" technique was of little use, as most extrasolar planets were found because of wobbles in the orbits of their parent stars, tugged by the planet's gravity. 

 

Most that were found this way were many times bigger than Jupiter and stiflingly close to their stars. But the Kepler mission finds smaller, Earth-like planets by patiently waiting for one to pass across the face of a star, momentarily reducing its light. 

 

Kepler's alignment of star, planet and Earth puts this approach in pole position to make the find.

 

John Grunsfeld, the associate administrator for Nasa's science missions, said: "The Kepler spacecraft has certainly turned out to be a rock star of science. The discovery of these rocky planets in the habitable zone brings us a bit closer to finding a place like home. 

 

"It is only a matter of time before we know if the galaxy is home to a multitude of planets like Earth, or if we are a rarity."


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Researchers Map the 3D Structure of the Telomerase Enzyme

Researchers Map the 3D Structure of the Telomerase Enzyme | sciences I 3> | Scoop.it
Researchers from UCLA and UC Berkeley have, for the first time ever, solved the puzzle of how the various components of an entire telomerase enzyme complex fit together and function in a three-dimensional structure.

 

The telomerase enzyme, which is known to play a significant role in aging and most cancers, represents a breakthrough that could open up a host of new approaches to fighting disease.

 

The creation of the first complete visual map of thetelomerase enzyme, which is known to play a significant role in aging and most cancers, represents a breakthrough that could open up a host of new approaches to fighting disease, the researchers said.

"Everyone in the field wants to know what telomerase looks like, and there it was. I was so excited, I could hardly breathe," said Juli Feigon, a UCLA professor of chemistry and biochemistry and a senior author of the study. "We were the first to see it."


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Le dernier Juracirque park : vite, vite, clonons des mammouths ! Avant que les éléphants ne s’éteignent…

Le dernier Juracirque park : vite, vite, clonons des mammouths ! Avant que les éléphants ne s’éteignent… | sciences I 3> | Scoop.it
Des chercheurs sont sur le point de redonner vie à une espèce éteinte de grenouilles Rheobatrachus silus (la grenouille plate à incubation gastrique), et voici qu’on nous reparle de cloner des mammouths !

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Carbon nanotube transistors designed to detect cancer biomarkers

Carbon nanotube transistors designed to detect cancer biomarkers | sciences I 3> | Scoop.it
New technique could give conventional immunoassays a run for their money

 

Carbon-nanotube transistors could be used to detect minute quantities of disease biomarkers, such as the proteins implicated in prostate cancer, according to new experiments by researchers in the US. The technique could rival conventional methods when it comes to sensitivity, cost and speed.

 

Conventional techniques to detect proteins are typically based on some form of "immunoassay", with the most famous of these being enzyme-linked immunosorbent assay (ELISA). This technique involves introducing an enzyme-modified antibody protein to an unknown amount of target molecule or protein, known as an antigen, and allowing them to bind together. Unreacted antibodies are washed away, leaving behind only antibody–antigen pairs.

 

The reaction can usually be detected by a colour change in the solution or by a fluorescent signal. The degree of colour change or fluorescence depends upon the number of enzyme-modified antibodies present, which in turn depends on the initial concentration of antigen in the sample.

 

Although such tests are routinely used in hospitals and clinics, they are quite long, taking several days or even weeks to complete. They are also costly, complicated to perform and can only detect single proteins at a time.

"Our new nanotube sensors are relatively simple compared to these ELISA tests," team member Mitchell Lerner, at the University of Pennsylvania, told physicsworld.com. "Detection occurs in just minutes, not days, and even at the laboratory scale, the cost of an array of 2000 such sensors is roughly $50 or 2.5 cents per sensor."

 

More importantly still, the sensors are much more sensitive to the target proteins in question. Indeed the Pennsylvania researchers showed that they could detect a prostate-cancer biomarker called osteopontin (OPN) at 1 pg/mL, which is roughly 1000 times lower than that possible with clinical ELISA measurements.


Detecting Lyme disease: The team, which is led by A T Charlie Johnson of Penn's Department of Physics and Astronomy, made its nanotube sensors by attaching OPN-binding antibodies to carbon-nanotube transistors on a silicon chip. Many proteins in the body bind very strongly to specific target molecules or proteins, and OPN is no exception. When the chip is immersed in a test sample, the OPN binds to the antibodies, something that changes the electronic characteristics of the transistor. Measuring the voltage and current through each device thus allows the researchers to accurately measure how much OPN there is in the sample.


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