TRITON Magazine Fall 2016 | Page 17

EXPLORING KNOWLEDGE

WHAT WAS I SAYING ?

Insights into how your thoughts run off the rails .

BY INGA KIDERRA
YOU ’ RE ON THE VERGE of something brilliant , a groundbreaking , gamechanging idea , when suddenly a phone rings and … gone ! Your train of thought derails and you ’ re left wondering what you were thinking about in the first place . Thanks to a new study of the brain ’ s electrical activity , UC San Diego researchers have a theory of just how that happens .
Neuroscientist and professor of psychology Adam Aron led the study , which suggests that the same brain system involved in interrupting body movement also interrupts cognition . The culprit appears to be one part of the brain ’ s overall stopping system — the subthalamic nucleus ( STN ).
Previous research by Aron and colleagues has shown that the STN is engaged for a “ broad stop ”— the whole-body jolt experienced , for example , when you ’ re about to exit an elevator yet there ’ s another person waiting outside the doors .
The study analyzed signals from the scalp in 20 healthy subjects as well as signals from electrode implants in the STNs of seven people with Parkinson ’ s disease . ( In Parkinson ’ s , the STN is the main target for therapeutic deep brain
stimulation , or a “ brain pacemaker .”)
Participants were asked to remember a string of letters while working on a memory task , and then were tested for recall . When participants were intentionally distracted by an audio clip of birdsong , however , monitors found that this unexpected sound manifested the same brain signature as physically stopping the body , engaging the STN . And the more the STN was engaged , the more it affected the subjects ’ working memory , and they forgot the letters they had seen .
More study will determine a correlative or a causal link . If further research bears out the connection , researchers wonder if the phenomenon might be an adaptive feature of the brain , something that evolved long ago as a way to clear thoughts and refocus . Consider Aron ’ s prehistoric example : You ’ re walking along the African savannah gathering firewood , daydreaming about the day ’ s meal , when you hear a rustle in the grass . You make a sudden stop — your thoughts of dinner are gone as you shift focus to what made that noise ... so you don ’ t become dinner yourself .
Aron ’ s findings may also give insights into the nature and treatment of
Parkinson ’ s disease . The same brain system implicated in “ over-stopping ” or “ freezing ” movement in Parkinson ’ s patients might also be what keeps them over-focused , with a thought stream so stable it can be hard to interrupt . More speculatively , the STN may additionally play a role in conditions characterized by distractibility , like attention deficit hyperactivity disorder .
THINKING CAP A study led by neuroscientist and professor of psychology Adam Aron used electroencephalography to analyze the brain activity of healthy volunteers as they completed a memory task .
Photo : Nathalie Belanger
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