Pioneering Research Helps to Unravel the Brain’s Vision Secrets

Feb. 3, 2013 — A new study led by scientists at the Universities of York and Bradford has identified the two areas of the brain responsible for our perception of orientation and shape.


 

Using sophisticated imaging equipment at York Neuroimaging Centre (YNiC), the research found that the two neighbouring areas of the cortex — each about the size of a 5p coin and known as human visual field maps — process the different types of visual information independently.

The scientists, from the Department of Psychology at York and the Bradford School of Optometry & Vision Science established how the two areas worked by subjecting them to magnetic fields for a short period which disrupted their normal brain activity. The research which is reported in Nature Neuroscience represents an important step forward in understanding how the brain processes visual information.

Attention now switches to a further four areas of the extra-striate cortex which are also responsible for visual function but whose specific individual roles are unknown.

The study was designed by Professor Tony Morland, of York’s Department of Psychology and the Hull York Medical School, and Dr Declan McKeefry, of the Bradford School of Optometry and Vision Science at the University of Bradford. It was undertaken as part of a PhD by Edward Silson at York.

Researchers used functional magnetic resonance imaging (fMRI) equipment at YNiC to pinpoint the two brain areas, which they subsequently targeted with magnetic fields that temporarily disrupt neural activity. They found that one area had a specialised and causal role in processing orientation while neural activity in the other underpinned the processing of shape defined by differences in curvature.

Professor Morland said: “Measuring activity across the brain with FMRI can’t tell us what causal role different areas play in our perception. It is by disrupting brain function in specific areas that allows the causal role of that area to be assessed.

“Historically, neuropsychologists have found out a lot about the human brain by examining people who have had permanent disruption of certain parts of the brain because of injury to it. Unfortunately, brain damage seldom occurs at the spatial scale that allows the function of small neighbouring areas to be understood. Our approach is to temporarily disrupt brain activity by applying brief magnetic fields. When these fields are applied to one, small area of the brain, we find that orientation tasks are harder, while disrupting activity in this area’s nearest neighbour only affected the ability to perceive shapes.”

Dr McKeefry added: “The combination of modern brain scanning technology along with magnetic neuro-stimulation techniques provides us with a powerful means by which we can study the workings of the living human brain.

“The results that we report in this paper provide new insights into how the human brain embarks upon the complex task of analysing objects that we see in the world around us.

“Our work demonstrates how processing of different aspects of visual objects, such as orientation and shape, occurs in different brain areas that lie side by side. The ultimate challenge will be to reveal how this information is combined across these and other brain areas and how it ultimately leads to object recognition.”


Story Source:

The above story is reprinted from materials provided byUniversity of York, via AlphaGalileo.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. Edward H Silson, Declan J McKeefry, Jessica Rodgers, Andre D Gouws, Mark Hymers & Antony B Morland.Specialized and independent processing of orientation and shape in visual field maps LO1 and LO2Nature Neuroscience, 2013 DOI: 10.1038/nn.3327
University of York (2013, February 3). Pioneering research helps to unravel the brain’s vision secrets. ScienceDaily. Retrieved February 4, 2013, from http://www.sciencedaily.com/releases/2013/02/130203145511.htm
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Dung Beetles Follow the Milky Way: Insects Found to Use Stars for Orientation

Jan. 24, 2013 — An insect with a tiny brain and minimal computing power has become the first animal proven to use the Milky Way for orientation. Scientists from South Africa and Sweden have published findings showing the link between dung beetles and the spray of stars which comprises our galaxy.

The dung beetle is the first animal proven to use the Milky Way for orientation. (Credit: Emily Baird)

Although their eyes are too weak to distinguish individual constellations, dung beetles use the gradient of light to dark provided by the Milky Way to ensure they keep rolling their balls in a straight line and don’t circle back to competitors at the dung pile.

“The dung beetles don’t care which direction they’re going in; they just need to get away from the bun fight at the poo pile,” said Professor Marcus Byrne from Wits University.

Byrne and his team previously proved that dung beetles use the sun, the moon and polarised light for orientation. In their experiments, they gave the beetles “caps” which blocked light from reaching their eyes. The team also discovered that the beetles climb on top of their dung balls to perform an orientation “dance” during which they locate light sources to use for orientation.

Now, further experiments, conducted under the simulated night sky of the Wits Planetarium, have shown that the beetles also use the Mohawk of the Milky Way — giving new meaning to dancing with the stars!

“We were sitting out in Vryburg (conducting experiments) and the Milky Way was this massive light source. We thought they have to be able to use this — they just have to!” said Byrne.

Not all light sources are equally useful landmarks for a dung beetle. A moth keeping a constant angle between itself and a candle flame will move in a circle around the flame. However, a celestial body is too far away to change position relative to a dung beetle as it rolls its ball, with the result that the beetle keeps travelling in a straight line.

The scientists suspect the beetles have a hierarchy of preference when it comes to available light sources. So if the moon and the Milky Way are visible at the same time, the beetles probably use one rather than the other.

A few other animals have been proven to use stars for orientation, but the dung beetle is the first animal proven to use the galaxy.


Story Source:

The above story is reprinted from materials provided byWits University, via AlphaGalileo.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. Marie Dacke, Emily Baird, Marcus Byrne, Clarke H. Scholtz, Eric J. Warrant. Dung Beetles Use the Milky Way for OrientationCurrent Biology, 2013; DOI:10.1016/j.cub.2012.12.034
Wits University (2013, January 24). Dung beetles follow the milky way: Insects found to use stars for orientation. ScienceDaily. Retrieved January 28, 2013, from http://www.sciencedaily.com/releases/2013/01/130124123203.htm