Don’t you just hate it when you have something really good to say but the train of thought vanishes into thin air…

So irritating, isn’t it?!

Well now, researchers from the University of California, San Diego, have uncovered exactly where said thought goes.

Using electrodes to track changes in the brain, scientists were able to pinpoint exactly what happens the moment we get startled and lose track of thought, allowing them to determine a link between our fading thoughts and a typical symptom of Parkinson’s disease.

“An unexpected event appears to clear out what you were thinking,” said Adam Aron, a neuroscientist at UC San Diego and lead author of the study.

The experiment revealed that the brain engages in a physical stopping order which has the potential to stop a running train of thought. This can occur when someone interrupts you mid-sentence, or when a loud noise catches you off guard and causes you to lose track of what you were saying.

“We know what the electrical signals look like when somebody has to stop a movement,” Aron told NBC News.

“The radically new idea is just as the brain’s stopping mechanism is involved in stopping what we’re doing with our bodies it might also be responsible for interrupting and flushing out our thoughts.

“We are providing a neural mechanism by which that happens,” he added. “The same stopping system that gives you that kind of jolt when you are getting out of the elevator, and someone else is in your way and you have to stop, that same stopping system is stopping your train of thought.”

Focusing on a part of the brain’s stopping system called the subthalamic nucleus, scientists asked participants to wear an electrode cap as they performed a computer-based memory task, and tried to measure whether a surprise could make them lose concentration.

Participants were shown two long strings of consonants and told to decide whether the second was identical to the first, meaning they had to keep the first sequence in mind as they tried to soak in the second.

At the start of the test, scientists either played a simple tone or the sound of birds singing. As stated in the journal Nature Communications, the birds were more likely to disturb thought patterns with 21 participants slowing down or making mistakes to the sound of birdsong.

Next, scientists asked another 22 participants to undertake the test wearing an electrode cap, while seven participants who suffered from Parkinson’s also performed a similar test.

Those who had Parkinson’s had the electrodes implanted in their brains to help treat their symptoms, meaning their cognitive activity could be read more accurately than those just wearing the cap.

Researchers found that the more the subthalamic nucleus was engaged by the startling stimulus, the more likely it was that participants would make errors.

“We’ve shown that unexpected, or surprising, events recruit the same brain system we use to actively stop our actions, which, in turn, appears to influence the degree to which such surprising events affect our ongoing trains of thought,” said cognitive neurologist Jan Wessel, who worked on the study and who is now at the University of Iowa.

The subthalamic nucleus is linked to various symptoms of Parkinson’s – the inability to quickly shift focus as well as the inability to initiate motion. Patients have also been known to get locked onto a thought, unable to shift their attention away from it. Electrodes implanted in the brains of patients are meant to treat these symptoms.

If a similar thing was happening in the brains of healthy participants, researchers say it could be the system itself that is universal, meaning it could be possible to train people to overcome such distractions.

Additional reporting by NBC News.

Image via Flickr.

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