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Discovering how the brain pays attention
There is a basic premise in visual attention – that is, that humans and primates can attend to something without moving their eyes to that object. We know this well when we can pay attention to something in our peripheral vision or when a parent can read the newspaper and keep their nearby child’s activity under their watchful eye. In the animal world, this ability is useful when direct eye contact can result in conflict.
Scientists were unsure how closely eye movements were tied to the phenomenon of attention and two neuroscientists from Princeton Tirin Moore and Katherine Armstrong showed that the brain circuits that control eye movements can serve a double function. They can program eye movements as well as trigger the amplification or suppression of signals that come in from the locations where the eyes could move.
In a recent issue of Nature, these researchers believe that this is the first study to pinpoint a neural mechanism behind a fundamental of mental activity of being able to direct attention to one thing as opposed to another. "Without regulating your attention, you would orient to everything that appears and moves. An organism that couldn't filter anything just wouldn't work. It would be in a state of constant distraction," said Moore. "This work shows that, whether we are moving our eyes or not, the networks that control eye movements may be a source of that filtering."
The process in brief
Using monkeys, the researchers pinpointed the exact area of the brain that not only controls eye movements but the neurons at that site that made the eyes move. They then located a single neuron, in another part of the brain, that was responsible for processing visual stimuli from precisely the same location targeted by neurons at the eye movement site.
Through electrical stimulation of the specific neurons and observing the results, the researchers concluded “that the very act of preparing an eye movement to a particular location caused an amplification of signals from that area. These eye movement neurons acted like a volume control on an amplifier, controlling the strength of the signal from one particular spot in space, but not altering the quality of that signal. By stimulating neurons in the eye movement area, the researchers in effect forced the animal to shift its attention from one location to another even though it did not move its eyes.”
What’s next
The possibilities to expand this study to others are really interesting especially since until now, there has been no real way to monitor visual information flow or reproduce it in the laboratory. This will lead to other studies of spatial relations, other aspects of attention, short-term memory, and visual planning. In the process, we will discover more about the amazing set of circuits that we not only take for granted but often don’t even notice. It also suggests that we may be able to look at and possibly even treat disabilities at the individual neural circuit or neuronal level.
9:16:24 PM 
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