Tuesday, March 24, 2015

Brain's light Detecter is not so Simple After All

visual tract in the brain



 There is plenty of indication that all is not so simple and this begins the process of discovering how.  It is also apparent the something drives internal imaging as well and somehow this correlates with our visual systems.

We also have significant unused range that needs to be better understood.

At the same time as we go into space we will want to sharply widen our visual range as well to be able to detect other parts of the spectrum.  You sort of want to see killing radiation.
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BRAIN’S LIGHT DETECTOR IS NOT SO SIMPLE AFTER ALL 

Visualization of the human visual tract. The lateral geniculate nuclei (LGN) are the small grey nodes midway between the eyes at the top and the visual cortex at the bottom. (Credit: Pittsburgh Supercomputer Center)

Posted by David Salisbury-VU on March 9, 2015

http://www.futurity.org/brains-visual-cortex-870742/

Neuroscientists generally think of the front end of the human visual system as a simple light detection system.

The patterns produced when light falls on the retina are relayed to the visual cortex at the rear of the brain, where all of the “magic” happens. That’s when the patterns are transformed into our 3D view of the world. 

Now, however, a brain imaging study challenges this basic assumption. 

Using high-resolution functional magnetic resonance imaging (fMRI), researchers discovered that more complex processing occurs in the initial stages of the visual system than previously thought.

Specifically, they have found evidence of processing in the human lateral geniculate nucleus (LGN), a small node in the thalamus in the middle of the brain that relays nerve impulses from the retina to the primary visual cortex. The details of the work were recently published in the journal Nature Neuroscience.

A MORE COMPLICATED VIEW

An important function of the visual cortex is the processing of rudiments of shape, the angles of lines and edges, which are important for defining the outlines of objects.


The researchers found that the human LGN is also sensitive to the orientation of lines and that this effect is enhanced when a person simply pays attention to the orientations in an image.

“These findings demonstrate that even the simplest brain structures may play a fundamental role in complex neural processes of perception and attention,” says Frank Tong, professor of psychology at Vanderbilt University, who conducted the study with postdoctoral fellow Michael Pratte and Sam Ling at Boston University.

“The findings challenge the conventional wisdom about how and where in the brain the processing of visual orientation information first occurs,” says Michael A. Steinmetz, acting director of the Division of Extramural Research at the National Eye Institute, which provided funding for the study.

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