Over the past few decades, researchers in the neuroscience field have demonstrated that the cerebral cortex generates predictions, and in response, neurons in charge of sensory processing encode the difference between our predictions and reality.
Below we review how our ears and brains work together to help us hear, as well as what one study has shown about this topic.
How We Hear
Soundwaves from our environments are captured by the outer ear and travel down the ear canal, which leads to the eardrum. When the soundwaves hit the eardrum, vibrations are created, which pass through three tiny bones inside the middle ear called the malleus, incus and stapes. These vibrations reach the fluid-filled cochlea within the inner ear, causing the fluid to move. This movement activates the tiny hair cells that line the cochlea, called stereocilia, creating an electrical impulse. This electrical impulse travels via the auditory nerve to the brain, where it is interpreted as sound.
About the Study
The 2020 study, entitled, “Abstract rules drive adaptation in the subcortical sensory pathway,” was published in the journal Neuroscience. The study was led by Dr. Katharina von Kriegstein, who was assisted by other researchers at TU Dresden.
During the study, researchers used functional magnetic resonance imaging (fMRI) to measure the brain responses of 19 participants. As each participant listened to a sequence of sounds, they were asked to identify one sound that deviated from the others. Then, their expectations were manipulated so that they would expect the deviant sound during certain parts of the sequences.
The term “predictive coding” describes perception as a process of hypothesis testing and assumes that the brain is constantly generating predictions about what we will perceive in the world. For example, like when we are at Westminster City Park, and then the brain detects differences between the predictions and what actually occurs.
According to the study authors, “These results provide first unambiguous evidence of abstract processing in a subcortical sensory pathway. They indicate that our prior beliefs alter the neural representation of the outside world even at initial points of the processing hierarchy.” To learn more or to schedule an appointment with a hearing expert, call Advantage ENT & Audiology today.