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article imageParts of the brain fall asleep and wake up again

By Tim Sandle     Dec 9, 2016 in Science
When people are awake the brain’s activity moves through states described as waves. This new observation seems to relate to how much attention is paid at a given point in time and may explain attention lapses.
The new research from Stanford University indicates that small areas of the brain are independently falling asleep and waking back up all the time. This is well established when someone is asleep, but the effect has not been detected when a person is awake, until now. The pattern appears strange to scientists and the areas of the brain that cycle in and out appear to do so independently.
Looking more closely, the neurons in these regions appear to be cycling at different rates, in that they show different levels of activity. This variation was shown using monkeys and probes pushed into the brain which allowed the rates of neurons switching on and off (or ‘firing’ at different rates) to be recorded.
What was interesting was the pattern: the firing on and off with neurons in different brain regions when a person is awake is very similar to what happens with the entire brain when a person is asleep. This information suggests that the processes that regulate brain activity in sleep might also play a role in the degree of attention a person shows when they are awake.
Explaining this further, Dr. Tatiana Engel, who led the study, notes: "Selective attention is similar to making small parts of your brain a little bit more awake.” The researcher adds: "During an on state the neurons all start firing rapidly. Then all of a sudden they just switch to a low firing rate."
The recorded neuron cycles are very short, taking place in fractions of seconds, which means they are not noticeable when a person is awake. It is thought the patterns reflect how a person pays attention and responds to the world. The research with monkeys demonstrated that when the monkeys spent more time paying attention to something the neurons tended to remain in the active state; and the reverse was so when less attention was paid.
The inference of the research with people is that the cycling may explain why people sometimes think they are paying attention when in fact they are missing things. Interestingly the neuron cycling also correlates with pupil dilation, where alert animals and humans tend to have pupils that are more dilated.
The findings are published in the journal Science, in a paper titled “Selective modulation of cortical state during spatial attention.”
More about Brain, Sleep, Wake, Awake, Neurons
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