The Role of the Auditory Brainstem in Regularity Encoding and Deviance Detection

Abstract

How does a listener perceive the auditory world and make sense from the myriad of concurrent sounds in the noisy and complex soundscape impinging our ears as a continuous flow? A major emerging view in cognitive auditory neuro- science is that the auditory system implements a pervasive mechanism by which dynamic auditory input is modeled into neural traces of regularities that allow the system to derive perceptual auditory objects. A large number of studies that used auditory sequences of various statistical complexities and that were performed with a range of neuroscience methods (e.g., neuro-imaging, electroencephalography and auditory evoked potentials, single neuron recordings) together have shown that regularity encoding and deviance detection is a key property of the auditory cortex. Furthermore, recordings in the inferior colliculus (IC) and the auditory thalamus of experimental animals have disclosed stimulus-specific adaptation (SSA) at these levels of the auditory pathway, challenging the corticocentric view of regularity encoding and deviance detection. Together with recent experiments using oddball sequences to measure early auditory evoked potentials, such as the middle latency response (MLR) and particularly the frequency-following response (FFR), those studies support the emerging view that regularity encoding and deviance detection are a key functional properties of the entire auditory system from at least the IC to high-order auditory cortical regions, and that the subcortical auditory pathway can implement certain forms of “primitive intelligence”, thereby contributing to audi- tory cognition.