(ORDO NEWS) — If you’ve ever had an imaginary argument in your head, you may have “heard” two voices at once. Your own inner voice and the voice of another participant in the dispute. You may even have “heard” the other person’s accent or tone of voice.
What happens in the brain during this internal monologue? How is it that you can “hear” your thoughts?
It turns out that the same processes occur in the brain as when pronouncing words aloud.
Internal monologues are considered an imitation of open speech, says Helene Louvenbroek, a senior researcher in neurolinguistics and head of the language team at the Psychology and Neurocognition Laboratory of CNRS, a French national research institute.
In childhood, we are virtual sponges, absorbing new information from all sides. Children playing alone often say dialogue out loud, such as between a toy truck and a teddy bear. Between the ages of 5 and 7, this verbalization moves inward, Levenbrook says.
Earlier research has shown that the brain is as active in internal speech as it is in verbalized speech. When study participants were asked to consciously “speak” inside their heads while lying in an MRI machine, the scientists could see the brain regions that process auditory information fire up, as if the participant had actually heard the words.
“The cerebral regions activated during internal speech are very similar to those activated during open speech,” Levenbrook. These areas include the frontal lobe of the left hemisphere and the parietal lobe, which help process external stimulation.
But when you think of something like a fictional argument with another person, the brain goes one step further. During this internal argument, you play two roles: yourself and the person you are arguing with. Playing yourself activates the auditory centers on the left side of your brain, Levenbrook says.
But when you internally switch into the role of the person you’re arguing with, “there’s a sort of shift in brain activation to the right hemisphere,” to equivalent areas like the parietal and frontal lobes, she continues.
If you look at the situation from a different perspective, even if you create this perspective in your head, it leads to a shift in which areas of the brain are involved.
The researchers also observed this phenomenon when participants were asked to imagine movement, Leowenbrook continues. For example, dancers use different parts of the brain to imagine themselves dancing rather than someone else, a study published in the August issue of the journal Cerebral Cortex found.
It’s one thing to see these areas of the brain fire up when a person is told to think about something, but it’s much less clear what happens in our brains when we let our minds run wild, Leowenbrook said. Not all interior monologues are intentional. Sometimes words or sentences just pop up in your head, unprovoked.
This phenomenon could be related to “default mode,” says Robert Chavez, a neuroscientist at the University of Oregon. The DMN is a network of regions in the brain that are active when it is not busy with a specific task.
The DMN is thought to be involved in aspects of inner thinking such as searching for memories, imagining the future, or interoception – feeling or “feeling” what is going on in your body, such as hunger or thirst.
“The default mode network seems to be more active when your mind is in an idle state,” Chavez told Live Science.
Because the default mode network involves planning for the future based on memories, recent experiences, and thought associations, this combination of activities is thought to start an internal monologue when you are focused on yourself.
Much more research needs to be done to understand how inner thoughts arise spontaneously, Leowenbrook says. Taken to extremes, internal thoughts can become dysfunctional, such as thought disorder after an unpleasant or traumatic event, or in mental disorders such as schizophrenia, in which people hear auditory hallucinations.
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