YOU’RE ON THE VERGE of something
brilliant, a groundbreaking, game-changing 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 S TN 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
BY INGA KIDERRA
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.
Insights into how your thoughts run off the rails.
WHAT WAS I SAYING?
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.