Scientists aren’t sure why you can’t get that song out of your head, but at least now they can see what’s going on in the brain while it’s stuck there. New research offers a first-time look at what’s going on in our brain when we hear an “imaginary sound” and shows there’s little difference in how our minds interpret sounds we actually hear and those we just think we do.
The study, published online on BioRXiv, represents the first time researchers have ever scientifically recorded the brain as it does something most of us likely do every day—hum or sing in our heads. To do this, they used an electrocorticography, a procedure that involves inserting electrodes into the brain. It is traditionally used to treat epileptics who can’t take medication, but the procedure also gives doctors an incredibly clear idea of what is going on inside the brain.
The volunteer in the study had epilepsy and was also a very proficient piano player. (The researchers noted that a musical background is known to improve auditory imagery ability, which may make readings easier.) The volunteer was asked to play a song on an electronic piano, then asked to hum the same song. This allowed the researchers to see what was going on inside his brain during both actions. Results revealed there was not much difference between the two, neurologically speaking.
The team looked at activity in areas of the brain known to be associated with auditory sounds: the pre-central gyrus (pre-CG), post-central gyrus (post-CG), supramarginal gyrus (SMG), medial temporal gyrus (MTG) and superior temporal gyrus (STG). Auditory brain activity during imagined music was the same as when the individual actually heard the music and when he simply hummed it in his head. The researchers concluded that those results suggested that our organization of sounds in the brain continues to occur, even in silence.
While the research is interesting in the way it finally shows the science of something we all do, it could also contribute to finding new ways to restore speech to those who have lost it through injury or disease. The research could particularly help individuals with aphasia, a condition usually induced by stroke but that can also be caused by brain injury. People with aphasia know what they want to say but are unable to verbally express themselves.
The team ultimately wants to know if they can develop a way for patients to re-create the “imaginary” speech they hear in their head but have trouble expressing acoustically. The first step toward doing this is understanding what exactly is going on when we hear sounds that aren’t actually there.
"We are at the very early stages of this research," said study researcher Stéphanie Martin, MedicalXpress reported. "Language is a much more complicated system than music: Linguistic information is nonuniversal, which means it is processed by the brain in a number of stages."