Branch retinal vein occlusion – blockage of the blood vessels that channel blood from the retina – is a common eye disease. A type of blood clot in the eye, the disease causes reduced vision, and people with the disease also typically have an increased risk of hypertension, diabetes and other serious conditions.

 Mette Bertelsen from the University of Copenhagen and colleagues photographically verified the diagnosis of branch retinal vein occlusion in 1168 people.

Scientists studying how songbirds stay on key have developed a statistical explanation for why some things are harder for the brain to learn than others.

"We've built the first mathematical model that uses a bird's previous sensorimotor experience to predict its ability to learn," says Emory biologist Samuel Sober. "We hope it will help us understand the math of learning in other species, including humans."

Sober conducted the research with physiologist Michael Brainard of the University of California, San Francisco.

Their results, showing that adult birds correct small errors in their songs more rapidly and robustly than large errors, were published in the Proceedings of the National Academy of Sciences (PNAS).

Nearby planetary nebula NGC 5189 and its bright gaseous nebula resembles a holiday ornament with a glowing ribbon - so it is perfect for a new Hubble image during the Christmas season.

 Planetary nebulae represent the final brief stage in the life of a medium-sized star. While consuming the last of the fuel in its core, the dying star expels a large portion of its outer envelope and this material then becomes heated by the radiation from the stellar remnant and radiates, producing glowing clouds of gas that can show complex structures, as the ejection of mass from the star is uneven in both time and direction.

Low pressure areas that dropped more than a foot of snow in some Midwestern states have prompted many warnings and weather advisories. Satellite data recently got a look at a major snowstorm.

On Dec. 21st, 2012, at 0729 UTC (2:29 a.m. EST), the Atmospheric Infrared Sounder (AIRS) instrument that flies aboard NASA's Aqua satellite captured an infrared image of the massive low pressure area that caused a major snowstorm in the Midwest and beyond. 

Brain imaging shows us what is happening during events and stimuli but it can't tell us much about how or why. Regardless, conclusion are often drawn and the poles of cultural debates are always jumping on the latest study to affirm their beliefs.

No one will be satisfied with a new University of Oxford study which concluded that the pain relief offered by cannabis is all subjective. The researchers found that an oral tablet of THC, the psychoactive ingredient in cannabis, tended to make the experience of pain more bearable, rather than actually reduce the intensity of the pain. MRI brain imaging showed reduced activity in key areas of the brain that substantiated the pain relief the study participants experienced. 

Taking body size into account, the black piranha and the extinct megapiranha have the most powerful bites of carnivorous fishes throughout known history.

It's no surprise they were both in the finals: The piranhas' specialized jaw morphology allows them to attack and bite chunks out of much larger prey and their aggressive nature, relatively small size and accessible populations make them a suitable group of predatory vertebrates in which to study the evolution of extreme biting capabilities. Even at their small body sizes, diet studies indicate that piranhas will attack and bite chunks of bony fins and flesh from prey many times larger than themselves.