From the feeling of clothes against the skin, to the sounds of cocktail party chatter, the human brain is constantly blocking out information that could be distracting. Now, a new study reveals how the brain achieves this ignoring feat.
In the study, researchers scanned people's brains while someone was lightly tapping on the participants' fingers and toes. When the researchers told the participants to ignore the feelings in their hands or feet, the scans showed more synchrony between brain waves in different parts of their noodles.
"Moment by moment, we’re really only doing one thing: We have to block things in the sensory and internal world," said Stephanie Jones, a neuroscientist at Brown University and senior author of the study published today (Feb. 3) in the Journal of Neuroscience. [10 Things You Didn't Know About the Brain]
In addition to helping scientists understand how the brain works, the findings have the potential to help people with chronic pain.
"We’re moving into an area of thinking about how we might use noninvasive brain stimulation to help with pain processing," Jones told Live Science.
Ignoring body parts
To find out what goes on in the brain when it ignores distractions, Jones and her colleagues put 12 volunteers in a magnetoencephalography (MEG) scanner, which reveals images of the rapidly changing magnetic fields that are produced by brain activity. The researchers told the volunteers they would feel taps on their left middle finger and their left big toe.
In some cases, the participants were told to pay attention to sensations in their finger and ignore those in their toe, and in others they were told to pay attention to their toe and ignore their finger.
The team used the MEG scanners to look at the synchrony between part of the somatosensory cortex, which processes touch in the hand, and the right inferior frontal cortex (rIFC), which is thought to be involved in blocking out information.
The researchers saw an increase in the synchrony between the "hand area" of the somatosensory cortex and the rIFC when the volunteers were told to only pay attention to the feelings in their foot and ignore those in their hand.
This increased synchrony suggests "there's some coordination" between part of the brain that processes information from the hand, and the part involved in blocking out distractions, Jones said.
Blocking out pain
Understanding how brain rhythms change when people ignore things in their environment isn't just an academic pursuit; Jones and her colleagues think it could be useful in treating people with chronic pain, who often are not helped by existing treatments.
For example, technologies like transcranial magnetic stimulation or transcranial direct current stimulation — which involve creating tiny magnetic or electrical fields in the brain, respectively — may be able to help people block out pain by producing the right patterns of brain activity, Jones said.
Previous research suggests that ignoring parts of the body "is something the brain can be trained to do," Jones said. Catherine Kerr, one of the new study's co-authors, previously did a study in which participants underwent the tapping task before and after meditation. She found that after meditation, people were able to shift their attention to different parts of their bodies faster and to a greater extent than before.