Scientists are investigating auditory central processing in an effort to better understand whether our expectations of sound affect how, and what, we hear. The research team’s current work is pursuing answers to the question: Do we hear sounds as they are, or do our expectations of what we are going to hear affect the way sound is processed? Through the use of computational neuroscience models, colleagues Emili Balaguer-Ballester, PhD, of Bournemouth University, and Andre Rupp, PhD, of Heidelberg University, are mapping the way the brain processes sound.
“Almost 80% of connections between central and pre-cortical areas during sound processing seem to be top-down, from the brain to the auditory peripheral system and not bottom-up, which is perhaps unexpected,” said Balaguer-Ballester. “As sound comes from an external stimulus, it would be fair to assume that most of our processing occurs from what we hear, but that is apparently not the case. What your brain expects to hear can be as important as the sound itself.”
According to an article in the May 16, 2015 edition of the Bournemouth Research Chronicle, Balaguer-Ballester says this assumption is backed up by the fact that it takes hundreds of milliseconds for sound to be processed along the neurons from the ear to the brain, which does not explain how we can immediately recognize the sex of a speaker or identify a melody after just a few milliseconds.
Rupp and his team are combining magneto and electroencephalography to map brain activity through recording electromagnetic currents which occur naturally in the brain and brainstem simultaneously. This allows for very detailed temporal information about how the brain processes sound to be recorded. Rupp sends his data to Balaguer-Ballester, who uses it to develop models to show in detail how the brain processes sound.
The researchers say that by understanding how sound is processed, new treatments for auditory processing disorders can potentially be found in the future.
“This could be the first step towards a better understanding of auditory central processing disorders in children,” said Balaguer-Ballester. “If their learning difficulties stem from the way their brain processes sound and not in their peripheral auditory system, this requires very different treatment to a child who develops serious hearing loss after an illness. Central processing disorders can lead to problems such as the delay of language development in children, so it is important to be able to pinpoint the neural parameter which is altered, in order to appropriately treat the cause of such an alteration.”
Source: Bournemouth Research Chronicle
Photo credits: Bournemouth University; Heidelberg University; © Suzanne Tucker | Dreamstime.com