The famed protein chain reaction that made mad cow disease a terror may be involved in helping to ensure that our recollections don't fade.
Prions are proteins with two unusual properties: First, they can switch between two possible shapes, one that is stable on its own and an alternate conformation that can form chains. Second, the chain-forming version has to be able to trigger others to change shape and join the chain. Say that in the normal version the protein is folded so that one portion of the protein structure—call it "tab A"—fits into its own "slot B." In the alternate form, though, tab A is available to fit into its neighbor's slot B. That means the neighbor can do the same thing to the next protein to come along, forming a chain or clump that can grow indefinitely.
For a brain cell, keeping a memory around is a lot of work. A variety of proteins need to be continually manufactured at the synapse, the small gap that interfaces one cell to another. But whereas a cell may have a multitude of synapses, the protein synthesis that grows and maintains the connection only occurs at specific ones that have been activated. Work in the sea slug Aplysia (a favorite of neuroscientists because of its large cells) showed that a protein called CPEB, for cytoplasmic polyadenylation element binding, is necessary to keep a synapse activated. CPEB acts as a prion.
Once the prion's chain reaction gets started it's self-perpetuating, and thus the synapse can be maintained after the initial trigger is gone—perhaps for a lifetime. But that still doesn't explain how the first prion is triggered or why it only happens in certain synapses and not others.
An answer comes from Si's work on fruit flies, published February 11 in PLoS Biology. Sex—and, in particular, male courtship behavior—is an ideal realm in which to test memory: If a female is unreceptive, the male will remember this and stop trying to court her. Earlier, Si’s team showed that if the fly's version of CPEB, called Orb2, is mutated so that it cannot act as a prion, the insect briefly remembers that the female is unreceptive but that memory fades over the course of a few days.
Now, Si's team has figured out how the cell turns on the machinery responsible for the persistence of memory—and how the memory can be stabilized at just the right time and in the right place.
Before the memory is formed a fly's neuron is full of a version of the prion called Orb2B. Although this version can switch shapes to form prions' characteristic clumps, it can't get started without the related protein Orb2A. In this week's paper Si and colleagues untangled the multipartnered dance that controls Orb2A's role. First, a protein called TOB binds to Orb2A, allowing it to persist intact in the cell. (Normally, it would be broken down within a few hours.) Once stabilized it needs to have a phosphate tag attached, and this is done by another protein called Lim kinase.
Crucially, Lim kinase is only activated when the cell receives an electrical impulse—and only targeted at that synapse, not any other synaptic connections the cell might also be making. That means that the prion chain reaction is turned on in the specific time and place it's needed. This, researchers say, means the cell has a mechanism to stabilize some synapses but not others—potentially explaining why some of our memories fade, whereas others last a lifetime.
Although work so far on these proteins has been in yeast, sea slugs, flies and mice, the human CPEB may operate in the same way to preserve memories. The next steps, both researchers agree, are to develop better techniques to see where in the brain prions are activated, and to dig into more questions about how the prion process is regulated. One burning question: When we forget, does that mean that the prion's chain reaction has been halted?
Sometime in the near future, you might take a bike ride with a couple of drones–one flying in front, one in back–to protect you from nearby cars. As you ride around tight corners, the “Cyclodrone” will shine a beacon of light to warn drivers that you’re there, hosting a tiny camera to record any accidents.
The design is one of several concepts from a team at frog design that wanted to rework the current evil image of the drone. “Drones are taking a beating in the press, being characterized as spies and assassins,” says Cormac Eubanks, who developed the Cyclodrone. “At frog, we are more fascinated by the design potential at the leading edge of technology. We believe now is the time to explore how drones could be a force for good.”
One way to increase the intelligence of a robot is to train it with a series of missions, analogous to the missions (aka levels) in a video game.In a developmental robot, the training would not be simply learning--its brain structure would actually...
Scientists say they have been able to successfully print new eye cells that could be used to treat sight loss. The proof-of-principle work in the journal Biofabrication was carried out using animal cells.
The Cambridge University team says it paves the way for grow-your-own therapies for people with damage to the light-sensitive layer of tissue at back of the eye - the retina. More tests are needed before human trials can begin.
Co-authors of the study Prof Keith Martin and Dr Barbara Lorber, from the John van Geest Centre for Brain Repair at the University of Cambridge, said: "The loss of nerve cells in the retina is a feature of many blinding eye diseases. The retina is an exquisitely organised structure where the precise arrangement of cells in relation to one another is critical for effective visual function.
"Our study has shown, for the first time, that cells derived from the mature central nervous system, the eye, can be printed using a piezoelectric inkjet printer. Although our results are preliminary and much more work is still required, the aim is to develop this technology for use in retinal repair in the future."
They now plan to attempt to print other types of retinal cells, including the light-sensitive photoreceptors - rods and cones.
Scientists have already been able to reverse blindness in mice using stem cell transplants. And there is promising work into electronic retina implants implants in patients.
Clara Eaglen, of the RNIB, said: "This is a step in the right direction as the retina is often affected in many of the common eye conditions, causing loss of central vision which stops people watching TV and seeing the faces of loved ones."
Few genes have made the headlines as much as FOXP2. The first gene associated with language disorders, it was later implicated in the evolution of human speech. Girls make more of the FOXP2 protein, which may help explain their precociousness in learning to talk. Now, neuroscientists have figured out how one of its molecular partners helps Foxp2 exert its effects.
The findings may eventually lead to new therapies for inherited speech disorders, says Richard Huganir, the neurobiologist at Johns Hopkins University School of Medicine in Baltimore, Maryland, who led the work. Foxp2 controls the activity of a gene called Srpx2, he notes, which helps some of the brain's nerve cells beef up their connections to other nerve cells. By establishing what SRPX2 does, researchers can look for defective copies of it in people suffering from problems talking or learning to talk.
Until 2001, scientists were not sure how genes influenced language. Then Simon Fisher, a neurogeneticist now at the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands, and his colleagues fingered FOXP2 as the culprit in a family with several members who had trouble with pronunciation, putting words together, and understanding speech. These people cannot move their tongue and lips precisely enough to talk clearly, so even family members often can’t figure out what they are saying. It “opened a molecular window on the neural basis of speech and language,” Fisher says.
A few years later, other researchers showed that the FOXP2 gene in humans differed from the chimp version by only two bases, the "letters" that make up DNA. That small difference may have affected Foxp2 performance such that animal calls could eventually transform into the human gift of gab. In 2009, a team put the human version of the gene in mice and observed that the rodents produced more frequent and complex alarm calls, suggesting these mutations may have been involved in the evolution of more complex speech. But how Foxp2 works has largely remained a mystery.
Huganir didn't start out trying to solve this mystery. He was testing 400 proteins to see if they helped or hindered the development of specialized junctions between nerve cells, called synapses, which allow nerve cells to communicate with one another. A single neuron can have up to 10,000 synapses, or connections to other neurons, Huganir says. Of the 10 proteins he identified, one that strongly promoted synapse formation was Srpx2, a gene other researchers had linked to epilepsy and language problems.
Huganir and his colleagues examined Srpx2 activity in isolated nerve cells, determining that it stimulated the formation of "excitatory" connections, ones where a "turn on" message was conveyed to the receiving nerve cell. Srpx2 also enhanced the number of excitatory connections in the part of the brain in developing mice that is the equivalent of the human language center, the researchers report online today in Science. Because Foxp2 regulates the activity of several genes, including Srpx2, Huganir and his team took a closer look at howFoxp2 affected this gene. When Foxp2 is around, Srpx2 makes fewer excitatory synapses, they report. It may be that the right balance of excitatory synapses and other connections may be necessary for complex vocalizations, Huganir suggests.
As a final test, the researchers looked to see how changing the activity of the Srpx2 gene affected alarm calls of baby mice. Mice pups separated from their moms call for help with squeals too high-pitched for humans to hear. When the researchers artificially inhibited Srpx2's activity, the mice squealed less. But the pups squealed normally again when gene activity was restored, Huganir and his colleagues report.
The work "shows that Foxp2 affects synapse formation through Srpx2," says Svante Pääbo, a paleogeneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who has studied Foxp2 in primates and in mice. "It is the first target gene of Foxp2 that has a clear function with respect to neuronal function."
MIT researchers have developed a lightweight structure whose tiny blocks can be snapped together much like the bricks of a child’s construction toy. The new material, the researchers say, could revolutionize the assembly of airplanes, spacecraft, and even larger structures, such as dikes and levees.
Neil Gershenfeld, director of MIT’s Center for Bits and Atoms, likens the structure — which is made from tiny, identical, interlocking parts — to chainmail. The parts, based on a novel geometry that Cheung developed with Gershenfeld, form a structure that is 10 times stiffer for a given weight than existing ultralight materials. But this new structure can also be disassembled and reassembled easily — such as to repair damage, or to recycle the parts into a different configuration.
The individual parts can be mass-produced; Gershenfeld and Cheung are developing a robotic system to assemble them into wings, airplane fuselages, bridges or rockets — among many other possibilities.
The new design combines three fields of research, Gershenfeld says: fiber composites, cellular materials (those made with porous cells) and additive manufacturing (such as 3-D printing, where structures are built by depositing rather than removing material).
With conventional composites — now used in everything from golf clubs and tennis rackets to the components of Boeing’s new 787 airplane — each piece is manufactured as a continuous unit. Therefore, manufacturing large structures, such as airplane wings, requires large factories where fibers and resins can be wound and parts heat-cured as a whole, minimizing the number of separate pieces that must be joined in final assembly. That requirement meant, for example, Boeing’s suppliers have had to build enormous facilities to make parts for the 787.
Pound for pound, the new technique allows much less material to carry a given load. This could not only reduce the weight of vehicles, for example — which could significantly lower fuel use and operating costs — but also reduce the costs of construction and assembly, while allowing greater design flexibility. The system is useful for “anything you need to move, or put in the air or in space,” says Cheung, who will begin work this fall as an engineer at NASA’s Ames Research Center.
The concept, Gershenfeld says, arose in response to the question, “Can you 3-D print an airplane?” While he and Cheung realized that 3-D printing was an impractical approach at such a large scale, they wondered if it might be possible instead to use the discrete “digital” materials that they were studying.
“This satisfies the spirit of the question,” Gershenfeld says, “but it’s assembled rather than printed.” The team is now developing an assembler robot that can crawl, insectlike, over the surface of a growing structure, adding pieces one by one to the existing structure.
Back in the fall of 2005 I took a class at the MIT Media Lab called Commonsense Reasoning for Interaction Applications taught by Henry Lieberman and TA'd by Hugo Liu.For the first programming assignment I made a project called AffectWorld, which allows...
One of the coolest visualization techniques to come along in recent years is the careful forensic reconstruction of likely facial features of deceased people from their bony remains, based on subtleties in bone structure and the knowledge of what each variation means, on average. Originally developed so police could put a face to unknown human remains (an application where it has been quite successful), the technique has spilled over into anthropology.
Recreating a face from the underlying bone involves painstaking work with myriad precision measurements so the muscle and skin will have the correct thickness and placement. It also involves having access to a database of enough samples so that the assigned features have a statistical likelihood of being correct. These are not wild guesses or dreamy-eyed artists impressions, but a reasonable recreation of a face that actually existed.
Done with: Timelapse 3D scanning of skull; Python Photogrammetry Tools; 3D Sculpting; Blender Screen capture; FFMPG Video edigint; Kdenlive.
From the abacus to the IBM personal computer, calculating devices have come a long way. Let's take a look through the history of these machines and the remarkable progress that came with the 20th century.
NASA's Mars rover Opportunity has made perhaps the biggest discovery of its nearly 10-year career, finding evidence that life may have been able to get a foothold on the Red Planet long ago.
The Opportunity rover spotted clay minerals in an ancient rock on the rim of Mars' Endeavour Crater, suggesting that benign, neutral-pH water once flowed through the area, scientists said.
"This is water you could drink," Opportunity principal investigator Steve Squyres of Cornell University told reporters today (June 7), explaining why the rock, dubbed "Esperance," stands out from other water-soaked stones the rover has studied.
The golf cart-size Opportunity and its twin, Spirit, landed on the Red Planet in January 2004 on three-month missions to search for signs of past water activity. The robotic explorers found plenty of such evidence (much of it indicating extremely acidic water, however), then just kept rolling along.
Spirit stopped communicating with Earth in 2010 and was declared dead a year later, but Opportunity is still going strong. In August 2011, the six-wheeled robot arrived at the rim of the 14-mile-wide Endeavour Crater, which it has been investigating ever since.
Opportunity has seen signs of clays in Endeavour rocks before, but in nowhere near the concentrations observed in Esperance, researchers said. Overall, Esperance provides strong evidence that ancient Mars was habitable.
"The fundamental conditions that we believe to be necessary for life were met here," Squyres said. The neutral-pH water that generated the clays probably flowed through the region during the first billion years of Martian history, he added, stressing that it's nearly impossible to pin down the absolute ages of Red Planet rocks without bringing them back to Earth.
Opportunity's latest discovery fits well with one made recently on the other side of the planet by the rover's bigger, younger cousin Curiosity, which found strong evidence that its landing site could have supported microbial life in the ancient past.
Ever wonder how Society of Mind came about? Of course you do.One of the key ideas of Society of Mind  is that at some range of abstraction levels, the brain's software is a bunch of asynchronous agents. Agents are simple--but a properly organized
In a world of delicate, experimental nano-drones, the Black Hornet is the first operational system deployed. A hand-launched observation drone, it can resist gusting winds, fly for 25 minutes, and travel nearly a mile from its operator. The autopilot can follow GPS coordinates to conduct a preplanned patrol or simply hover and stare. All in a drone that weighs less than 0.6 ounces.
At the AAAI 2013 Fall Symposia (FSS-13)12, I realized that I was not prepared to explain certain topics quickly to those who are specialists in various AI domains and/or don't delve into philosophy of mind issues.
As self-driving cars move from fantasy to reality, what kind of effect will they have on cities?
A research and urban prototyping project called Shuffle City investigates, and in the process, becomes a manifesto for a new kind of modern city--one that depends less on traditional public transportation like buses or light rail and more on creating a fleet of continuously moving automated vehicles to serve urban mobility needs.
Shuffle City looks at the new possibilities that could arise from cities transitioning to cars without drivers. If cars were put into some constant flow as a public good, and if people didn’t all have their own vehicles, there would be no need for the concrete wastelands and lifeless towers that serve as a parking infrastructure in the urban landscapes of car-centric cities like Phoenix and Los Angeles (Under the current ownership model, the average car spends 21 hours per day parked.)
The share of city space ruled by parking lots will shrink, making way for more green space, environmental buffers, workspace, housing, retail, and denser planning for more walkable cities...
How do we know whether our own actions were voluntary or involuntary? Intentional theories of sense of agency suggest that we consciously perceive the intentions that accompany our actions, but reconstructive theories suggest that we perceive our actions only through the body movements and other effects that they produce. Intentions would then be mere confabulations, and not bona fide experiences. Previous work on voluntary action has focused on immediate experiences of authorship, and few studies have considered memory for voluntary actions. We devised an experiment in which both voluntary action and involuntary movement always occurred at the same time, but could either involve the same hand (congruent condition), or different hands (incongruent condition). When signals from the voluntary and involuntary movements involved different hands, they could therefore potentially interfere in memory. We found that recall of a voluntary action was unaffected by an incongruent involuntary movement. In contrast, recall of an involuntary movement was strongly influenced by an incongruent voluntary action. Our results demonstrate an “intentional capture” of body movement by voluntary actions, in support of intentional theories of agency, but contrary to reconstructive theories. When asked to recall both actions and movements, people's responses are shaped by memory of what they intended to do, rather than by how their body moved.
Ten years ago, the discovery of Mimivirus, a virus infecting Acanthamoeba, initiated a reappraisal of the upper limits of the viral world, both in terms of particle size (>0.7 micrometers) and genome complexity (>1000 genes), dimensions typical of parasitic bacteria. The diversity of these giant viruses (the Megaviridae) was assessed by sampling a variety of aquatic environments and their associated sediments worldwide. We report the isolation of two giant viruses, one off the coast of central Chile, the other from a freshwater pond near Melbourne (Australia), without morphological or genomic resemblance to any previously defined virus families. Their micrometer-sized ovoid particles contain DNA genomes of at least 2.5 and 1.9 megabases, respectively. These viruses are the first members of the proposed “Pandoravirus” genus, a term reflecting their lack of similarity with previously described microorganisms and the surprises expected from their future study.
Pandoraviruses: Amoeba Viruses with Genomes Up to 2.5 Mb Reaching That of Parasitic Eukaryotes Nadège Philippe et al.
This paper presents a heuristic proof (and simulations of a primordial soup) suggesting that life—or biological self-organization—is an inevitable and emergent property of any (ergodic) random dynamical system that possesses a Markov blanket. This conclusion is based on the following arguments: if the coupling among an ensemble of dynamical systems is mediated by short-range forces, then the states of remote systems must be conditionally independent. These independencies induce a Markov blanket that separates internal and external states in a statistical sense. The existence of a Markov blanket means that internal states will appear to minimize a free energy functional of the states of their Markov blanket. Crucially, this is the same quantity that is optimized in Bayesian inference. Therefore, the internal states (and their blanket) will appear to engage in active Bayesian inference. In other words, they will appear to model—and act on—their world to preserve their functional and structural integrity, leading to homoeostasis and a simple form of autopoiesis.
Life as we know it Karl Friston
J. R. Soc. Interface 6 September 2013 vol. 10 no. 86 20130475
RedOrbit Researchers Create Touch-Based Interface That Can Be Applied Anywhere RedOrbit In 2002, Tom Cruise used “smart gloves” to manipulate images and video on a virtual touchscreen in Steven Spielberg's Minority Report.