When researcher Julian Asher goes to the symphony, he gets a sensory extravaganza. “When I hear a violin, I see something like a rich red wine,” says Asher…. “A cello is more like honey” [New Scientist]. Asher has a condition called synesthesia in which sensory information gets mixed in the brain; in Asher’s particular form, auditory-visual synesthesia, sounds cause him to see colors. Now, a study led by Asher may have uncovered the genetic source of the condition, which synesthetes say can be both a blessing and a curse.
The researchers collected DNA samples from 196 people who had auditory-visual synesthesia running in their families, they explain in the American Journal of Human Genetics [subscription required]. Asher expected to find a single gene associated with the condition, but scanning the genomes revealed that it was linked to four distinct regions, on chromosomes 2, 5, 6, and 12.
The region that was most strongly linked to synesthesia was an area on chromosome 2 that has also been strongly linked to autism. That doesn’t mean that the two conditions are related, per se, explained Ed Hubbard, a cognitive neuroscientist…. Instead, the common gene or genes are likely “more generally involved in how the brain gets built.” The study also pulled out a region on chromosome 6 that contains genes linked to dyslexia — especially interesting, “seeing as phonemes [the units of sound in language] and letters are two of the strongest synesthetic triggers,” Asher said [The Scientist].
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When you need to brainstorm ideas for a big project, get yourself to a room that’s painted blue. But when it’s time to proofread the final product, find a red room. Those are the implications of a fascinating new study that measured the effect that colors have on cognition. Researchers found that red can make people’s work more accurate, and blue can make people more creative [The New York Times]. Since people associate red with danger, it primes them to proceed with more caution and diligence, Zhu reasons, while blue’s oceanic connotations put them in a more adventurous mood.
Researcher Juliet Zhu decided to tackle the topic because previous studies had come up with inconsistent findings. Some studies had found that red enhances cognition, for example, while other studies suggest the opposite. Zhu suspected this might be because the work didn’t pay enough attention to which types of cognition were being affected. Red might enhance performance on some tasks, she reasoned, while impairing performance on others [ScienceNOW Daily News].
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The odd-looking spookfish is the only vertebrate known to have mirrors in its eyes, according to a new report. The mirrors gather and focus light better than lenses, which spookfish also have, and appear to be an adaptation for living in the murky depths of the Pacific Ocean. Scientists discovered the spookfish’s unusual anatomy after examining the first specimen of the fish ever caught alive. Researcher Ron Douglas found the rare specimen last year in the deep waters between Samoa and New Zealand, but no one on the research boat knew what it was. “It caught my attention because it looked like it had four eyes, and vertebrates with four eyes don’t exist,” says Douglas [New Scientist].
In fact, the spookfish only has two. Spookfish, also known as barreleyes, are a family of deep-sea fish with tubular eyes, rather like telescopes, that point upwards to capture the minimal sunlight that filters down from above. Each eye also has a part that points downward, forming what looks like a second pair of eyes. When researcher Julian Partridge looked at sections of the spookfish eye under the microscope, he discovered that the downward-pointing parts contain mirrors, made of tiny plates of guanine crystals, that help direct light onto the retina. Partridge explains that the mirrored “diverticular” eyes help capture light emitted by other animals: “At these depths it is flashes of bioluminescent light from other animals that the spookfish are largely looking for. The diverticular eyes image these flashes, warning the spookfish of other animals that are active, and otherwise unseen, below its vulnerable belly” [BBC News].
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In a remarkable experiment, researchers found that a man who was rendered completely blind by several strokes could deftly navigate an obstacle course unaided, easily avoiding boxes and sidling around pieces of office equipment. The patient, known only as TN, was left blind after damage to the visual (striate) cortex in both hemispheres of the brain following consecutive strokes. His eyes are normal but his brain cannot process the information they send in, rendering him totally blind [BBC News]. Researchers say TN’s successful performance was an example of the phenomenon “blindsight,” and say it suggests that some small amount of information is being transmitted from his undamaged eyes to a more primitive part of his brain, which operates beneath the level of consciousness.
TN usually walks with a cane, but researcher Beatrice de Gelder convinced him to put it aside and to try to navigate the obstacle course without its help. He was able to do so flawlessly, despite being unable to consciously see any of the obstacles. Head down and hands loose by his side, he twisted his body to slalom slowly but surely between a camera tripod and a swingbin, and neatly stepped around a random series of smaller items. “At first he was nervous,” says de Gelder. “He said he wouldn’t be able to do it because he was blind.” The scientists broke into spontaneous cheers when he succeeded [Nature News].
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Researchers have determined the mechanism by which the world’s simplest vision system works. A team of biologists spent a decade studying the larvae of the marine rag-worm Platynereis, a tiny creature with just two cells that respond to light and direct the worm to swim towards it. The rag-worm and other zooplankton like krill drift in the ocean’s water columns, swimming up from the depths towards the light in order to graze on marine plants called phytoplankton near the surface. This movement, called phototaxis, is the biggest biomass displacement in the world [AFP].
The rag-worm has two cells that work together as “proto-eyes”: one pigment cell and one light-sensitive cell. First, the pigment cell absorbs light and casts a shadow over the photoreceptor cell. The shape of the shadow varies according to the position of the light source. The photoreceptor cell then converts this light signal into electricity, sending it in a signal along a nerve that connects to a band of cells endowed with thin hairs, called cilia, that beat to displace water [AFP]. So although the worm sees no images, it can sense the difference between light and dark and swim in the right direction.
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Tennis referees are far more likely to make wrong “out” calls than wrong “in” calls, according to a new study. A quirk of our visual perception system, which helps us anticipate the motion of an object, seems to bias our perception of where a speeding tennis ball stops moving. “This is not a problem with referees,” says study co-author David Whitney…. “It’s a consequence of human visual processing … a visual illusion caused by a mechanism that allows the system to localize a moving object” [Scientific American].
The idea to study this visual illusion in a real-world context came to Whitney during a Wimbledon match as he watched a player challenge and overturn a referee’s call. For the study, published in Current Biology [subscription required], the researchers used Hawk-Eye technology, a system of high-speed cameras that is often used for contested calls in tennis matches. Three scientists independently reviewed video and instant replay of 4,457 randomly selected points from the 2007 Wimbledon championships. Of the 83 calls that the video and instant replay showed were wrong, 70 were “out” calls [Scientific American]. Without the visual bias, there should have been the same number of wrong “out” calls as “in” calls.
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In a promising result for gene therapy, researchers have dramatically improved the vision of several patients with a rare, inherited eye condition called Leber congenital amaurosis. The early study was intended to simply test the safety of the treatment, but the patients displayed such significant improvement that researchers decided to publicize the results.
Gene therapy works on a simple principle – to replace a malfunctioning gene, and restore function to a part of the body affected by a genetic disorder. In practice, however, it has proved very difficult to find ways to introduce the new gene copies in the correct tissues, and experiments in animals have had mixed results [BBC News].
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