It is well established that the images the observer sees are divided in half as they are sent to the two hemispheres of the brain. When a person looks at the center of an object, the image from the right half of the object will be sent to one hemisphere of the brain and the image of the left half is sent to the other. This is true whether a person uses one eye or two to look at the object. “Given that the primary visual areas in each hemisphere are seeing only half of the object, it has been assumed that communication between the hemispheres was needed to combine the information,” said Greene.
By using a high-speed LED array to display the images, Greene found evidence that the two sides of the retina interact to enhance the effectiveness of shape cues, which he describes as “linkage.” The cells in the retina appear to be coordinating their responses in a way that benefits shape recognition. Further, they do so with unexpected temporal precision.
The study was done by positioning dots around the outer boundaries of objects, forming stimuli similar to silhouettes. The dots were shown, in successive pairs, one pair after the other, and the observers were then asked to identify each shape. Recognition was best if time intervals that separated pairs and pair members were in the submillisecond range. This was true whether both members of the pair were displayed on the same side of the object or on opposite sides. “This finding suggests that the responses from the two sides of the retina are being linked in some manner, and the process of joining the two halves of an object is not done only in the brain,” says Greene.
“It is unlikely that the nerve signal being sent from the eye to the brain can be precise enough to preserve submillisecond timing differences,” says Greene. Also, for the brain to coordinate nerve signals being sent from opposite sides of the retina, communication between the two hemispheres would be needed. “It strains credulity that these additional processing steps could be accomplished while preserving submillisecond precision in the responses to pair members,” Greene says. He thinks it is more likely that cell structures in the retina link the responses prior to sending the information to the visual cortex. The retina itself may be assessing global relationships among boundary locations, these operations being required for recognition of the shape.
Rochester scientists discover gene controlling genetic recombination rates
23.04.2018 | University of Rochester
One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
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University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
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23.04.2018 | Physics and Astronomy
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