Mental time-travel in birds

Mental time-travel in birds

  10:22:00 AM    Science Lover

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Certain types of birds may track army ant swarms using sophisticated memory and the ability to plan for the future.

White Whiskered Puff bird Credit: Glenn M Duggan FZS

Some tropical birds collect their prey at army ant raids, where massive swarms of ants sweep through the forest and drive out insects. The behaviour of interest is called bivouac checking; it allows these birds to track the cyclical raid activity of army ant colonies.

Army ants have regular alternating periods of high and low raiding activity, and birds visit the ants’ temporary nest sites (bivouacs) to determine which colonies are raiding on a given day.

The new findings published today in the journal Behavioural Ecology, suggest that bivouac checking allows birds to keep track of multiple army ant colonies, keeping account of which colonies are in periods of high-raiding activity while avoiding colonies with low-raiding activity.

Recent research has discovered that birds check army ant bivouacs at the end of the day, after they have fed at the raid. They may use the information about the army ant nest location the next day to find the ants again, thus accessing a past memory (the nest location) to fulfil a future need (bird will be hungry tomorrow), also known as ‘mental time-travel’.

Two of the authors of the study Corina Logan of the University of Cambridge, and Sean O’Donnell of the University of Washington, observed bivouac checking behaviour in Monteverde, Costa Rica.

Mental time-travel consists of two elements: the ability to remember past events and the ability to anticipate and plan for future events. It has traditionally been considered a quality unique to humans. However, ever since Nicola Clayton of the University of Cambridge discovered that scrub jays (a species of large-brained crow) can remember the past and plan for the future, there have been a suite of studies showing evidence of this ability in other species as well. We now know that corvids (birds in the crow family), some primates, and possibly rats have all shown the ability to remember the past and plan for the future.

Corina Logan, said: “We suspect that future planning could be involved in bivouac-checking bird behaviour because the birds were checking bivouacs when they were not hungry, a behaviour that does not make sense until the next morning upon return to the bivouac when the bird finds the ants raiding again and encounters its next meal – a delayed benefit.”

Until recently, it has been difficult to find model systems for studying mental time travel in an ecologically relevant way. “The fact that we might have happened on a whole new system for exploring these capacities is quite exciting,” added Corina Logan.

Provided by University of Cambridge



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Taking Touch beyond the Touch Screen A prototype tablet can sense gestures, and objects placed next to it.

Taking Touch beyond the Touch Screen A prototype tablet can sense gestures, and objects placed next to it.

  10:05:00 AM    Science Lover

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A tablet computer developed collaboratively by researchers at Intel, Microsoft, and the University of Washington can be controlled not only by swiping and pinching at the screen, but by touching any surface on which it is placed.

In touch: The spacecraft on this tablet's
screen can be controlled by maneuvering
the toy on the table next to it. Credit: Intel

Finding new ways to interact with computers has become an important area of research among computer scientists, especially now that touch-screen smart phones and tablets have grown so popular. The project that produced the new device, called Portico, could eventually result in smart phones or tablets that take touch beyond the physical confines of the device.

"The idea is to allow the interactive space to go beyond the display space or screen space," says Jacob Wobbrock, an assistant professor at the University of Washington's Information School, in Seattle, who helped develop the system. This is achieved with two foldout cameras that sit above the display on either side, detecting and tracking motion around the screen. The system detects the height of objects and determines whether they are touching the surrounding surface by comparing the two views captured by the cameras. The approach make it possible to detect hand gestures as well as physical objects so that they can interact with the display, says Wobbrock.

In one demonstration, software tracks a small ball as it moves across the surface the tablet sits on. As the ball strikes the side of the tablet, a virtual ball appears on-screen following the same trajectory, as if the physical ball had entered the device. In this way the ball can be used to score on-screen goals. In another demonstration, the angle of a toy spaceship placed on the table next to the tablet controls the angle of a virtual spaceship onscreen, allowing the user to shoot down "asteroids."



Wobbrock says the same approach would work on smart phones and other pocket-sized devices. "As devices continue to shrink, they compromise the screen space. But with Portico you can reclaim the surrounding area for interactivity," he says.

With the tablet, Portico increases the usable area sixfold, says Daniel Avrahami a senior researcher at Intel Labs Seattle, who came up with the idea for Portico, and led its development, with help from Shahram Izadi at Microsoft Research in Cambridge, UK. For a 12-inch tablet, "that's the equivalent of a 26-inch screen," says Avrahami, who will present the work in October at the ACM User Interface, Software and Technology Symposium in Santa Barbara, California.

Eventually, says Wobbrock, it may be more practical, especially from a commercial standpoint, to use clip-on cameras instead of foldout ones, which tend to break more easily. But he also notes that the entire display might be replaced with a fold-up frame containing both cameras and a pico projector to produce the image on the surface below.

Eva Hornecker, a lecturer specializing in human-computer interaction at the University of Strathclyde, in Glasgow, Scotland, says there is growing interest in using cameras to detect hand gestures and objects among researchers.

"The problem with touch screens is you can't detect anything that's happening over the surface," Hornecker says. However, she notes that allowing interaction beyond the screen could introduce new challenges such as how to provide feedback so the user knows where the interactive area starts and ends.

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Multifunctional Nanoparticle Enables New Type of Biological Imaging

Multifunctional Nanoparticle Enables New Type of Biological Imaging

  12:30:00 PM    Science Lover

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Spotting a single cancerous cell that has broken free from a tumor and is traveling through the bloodstream to colonize a new organ might seem like finding a needle in a haystack. But a new imaging technique from the University of Washington is a first step toward making this possible.

On top are photoacoustic images taken for gold nanorods (left), the new UW particle that has a magnetic core and surrounding gold shell (center), and a simple magnetic nanoparticle (right). Below is the same image after processing to remove pixels not vibrating with the magnetic field. The center blob is retained because of the particles' magnetic core and is bright because of the particles' gold shell. (Credit: Xiaohu Gao, University of Washington)

UW researchers have developed a multifunctional nanoparticle that eliminates the background noise, enabling a more precise form of medical imaging -- essentially erasing the haystack, so the needle shines through. A successful demonstration with photoacoustic imaging was reported n the journal Nature Communications.

Nanoparticles are promising contrast agents for ultrasensitive medical imaging. But in all techniques that do not use radioactive tracers, the surrounding tissues tend to overwhelm weak signals, preventing researchers from detecting just one or a few cells.

"Although the tissues are not nearly as effective at generating a signal as the contrast agent, the quantity of the tissue is much greater than the quantity of the contrast agent and so the background signal is very high," said lead author Xiaohu Gao, a UW assistant professor of bioengineering.

The newly presented nanoparticle solves this problem by for the first time combining two properties to create an image that is different from what any existing technique could have produced.

The new particle combines magnetic properties and photoacoustic imaging to erase the background noise. Researchers used a pulsing magnetic field to shake the nanoparticles by their magnetic cores. Then they took a photoacoustic image and used image processing techniques to remove everything except the vibrating pixels.

Gao compares the new technique to "Tourist Remover" photo editing software that allows a photographer to delete other people by combining several photos of the same scene and keeping only the parts of the image that aren't moving. "We are using a very similar strategy," Gao said. "Instead of keeping the stationary parts, we only keep the moving part.

"We use an external magnetic field to shake the particles," he explained. "Then there's only one type of particle that will shake at the frequency of our magnetic field, which is our own particle."

Experiments with synthetic tissue showed the technique can almost completely suppress a strong background signal. Future work will try to duplicate the results in lab animals, Gao said.

The 30-nanometer particle consists of an iron-oxide magnetic core with a thin gold shell that surrounds but does not touch the center. The gold shell is used to absorb infrared light, and could also be used for optical imaging, delivering heat therapy, or attaching a biomolecule that would grab on to specific cells.

Earlier work by Gao's group combined functions in a single nanoparticle, something that is difficult because of the small size.

"In nanoparticles, one plus one is often less than two," Gao said. "Our previous work showed that one plus one can be equal to two. This paper shows that one plus one is, finally, greater than two."

The first biological imaging, in the 1950s, was used to identify anatomy inside the body, detecting tumors or fetuses. The second generation has been used to monitor function -- fMRI, or functional magnetic resonance imaging, for example, detects oxygen use in the brain to produce a picture of brain activity. The next generation of imaging will be molecular imaging, said co-author Matthew O'Donnell, a UW professor of bioengineering and engineering dean.

This will mean that medical assays and cell counts can be done inside the body. In other words, instead of taking a biopsy and inspecting tissue under a microscope, imaging could detect specific proteins or abnormal activity at the source.

But making this happen means improving the confidence limits of the imaging.

"Today, we can use biomarkers to see where there's a large collection of diseased cells," O'Donnell said. "This new technique could get you down to a very precise level, potentially of a single cell."

Researchers tested the method for photoacoustic imaging, a low-cost method now being developed that is sensitive to slight variations in tissues' properties and can penetrate several centimeters in soft tissue. It works by using a pulse of laser light to heat a cell very slightly. This heat causes the cell to vibrate and produce ultrasound waves that travel through the tissue to the body's surface. The new technique should also apply to other types of imaging, the authors said.

Co-authors are UW postdoctoral researchers Yongdong Jin and Sheng-Wen Huang and University of Michigan doctoral student Congxian Jia.

Research was funded by the National Institutes of Health, the National Science Foundation and the UW Department of Bioengineering.

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