Neural Mechanism Theories: Dissecting Mismatch Negativity and Stimulus-Specific Adaptation for a Deeper Understanding of Auditory Processing

The ability to automatically detect signal changes is essential to the survival for any organism. For example, an animal living in the forest can distinguish a relatively constant sound background, such as leaves blowing in the wind, from a sudden novel sound, such as a cracking branch, which might indicate the presence of a nearby predator. Distinct brain responses to novel sounds (as opposed to expected sounds) are known as mismatch negativity (MMN) in humans or stimulus-specific adaptation in animal. It is found that the neural response was attenuated by the repetitive stimulation of sound sequences, while the presentation of an unexpected stimulus enhances the neural responses. Three main hypotheses have been proposed concerning the this neural mechanisms: the model adjustment hypothesis, the neural adaptation hypothesis and predictive coding theory. The purpose of this study is to introduce theoretical perspectives within a fundamental scientific approach in order to elucidate MMN mechanisms. Additionally, we will review the literature that explains MMN from an audiological perspective through these theories.