Feb 242006

According to a study published recently in Nature, neurons firing synchronously help to focus the brain’s attention on certain tasks and lead to quicker response times. When neurons fire independently their electrical output is nothing but noise, and no coherent signal is discernible in the static. When even a few neurons fire synchronously, their individual signals reinforce one another, and a tone arises from the background noise. The study, a collaboration between Robert Desimone, from the McGovern Institute for Brain Research at MIT, and researchers at Radboud University in the Netherlands, expands on previous work by Desimone which concluded that neurons fired synchronously during periods of concentration. The new experiments indicate that neural synchronization also helps the brain detect and react quickly to events.

During the study the researchers focused on neurons in the V4 brain region of laboratory monkeys who were trained to confirm when they saw a dot of light projected on a screen in front of them change in color from white to yellow. The V4 region is a section of the visual cortex that reacts to orientation, spatial frequency, and color. The researchers measured the monkeys’ reaction times both when the dot was the only object on the screen and also when other similar colored lights were displayed in their field of vision as a distraction.

In addition to recording reaction times, the scientists measured the amount of synchronous neural activity before, during, and after the detection of the color change. They found that the more coordination that existed between neurons, the quicker the monkeys reacted to the change. The weaker the synchronization, the slower they responded. The response times correlated so well to synchronization that the researchers could tell a half a second ahead of the change how quickly the monkey would react based on its observed neural activity.

Additionally, the neuroscientists were able to tell when the monkeys were distracted by the extra lights. If their neurons were firing synchronously while the “distraction” lights were displayed it meant the monkeys were focusing on those lights and not ignoring them as they should. This loss of focus led to slower reaction times when the actual target light changed color.

Desimone hopes his research into neural synchrony will lead to breakthroughs in understanding and treating neural disorders that cause attention problems like ADHD.

Read the MIT press release about this study: “Neurons in sync focus attention, researchers find.”

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