Adaptation in auditory processing

Abstract

Adaptation is an essential feature of auditory neurons, which reduces their responses to unchanging and recurring sounds and allows their response properties to be matched to the constantly changing statistics of sounds that reach the ears. As a consequence, processing in the auditory system highlights novel or unpredictable sounds and produces an efficient representation of the vast range of sounds that animals can perceive by continually adjusting the sensitivity and, to a lesser extent, the tuning properties of neurons to the most commonly encountered stimulus values. Together with attentional modulation, adaptation to sound statistics also helps to generate neural representations of sound that are tolerant to background noise and therefore plays a vital role in auditory scene analysis. In this review, we consider the diverse forms of adaptation that are found in the auditory system in terms of the processing levels at which they arise, the underlying neural mechanisms and their impact on neural coding and perception. We also ask what the dynamics of adaptation, which can occur over multiple timescales, reveal about the statistical properties of the environment. Finally, we examine how adaptation to sound statistics is influenced by learning and experience and changes as a result of aging and hearing loss.

Listening loops and the adapting auditory brain

“…From a functional perspective, firing-rate adaptation seems important in the listening brain’s ability to adjust dynamically to the listening environments in response to changes in that environment, or in response to internal changes that alter its overall sensitivity or dynamics. Adaptive coding is a common phenomenon throughout the brain, and a recent review article provides an excellent primer for understanding the different cadences over which adaptation in the auditory brain unfolds, from the range of milliseconds to over the life-course, as well as potential mechanisms by which these cadences are set or arise ( Willmore and King, 2022 ).…”

Neural adaptation at stimulus onset and speed of neural processing as critical contributors to speech comprehension independent of hearing threshold or age

“…This would explain the fact that after removal of PTT influence by PNOT, the difference between both metrics remains a significant factor explaining variance, and it thus would reflect different nerve adaptation characteristics at the onset of the stimulus. In mammalian inner hair cells nerve adaptation at the onset is associated with vesicle depletion characteristic linked to synaptic fatigue or desensitization kinetic of postsynaptic receptors (Moser and Beutner, 2000; Goutman, 2017; Peterson et al, 2018; Willmore and King, 2023). Thus, a larger or smaller L EDPT -PTT differences that correlate with better or worse speech-in-quiet comprehension (Fig.…”

Hemispheric difference of adaptation lifetime in human auditory cortex measured with MEG

“…Adaptation, also called repetition suppression, is observed in all parts of the auditory system (Willmore & King, 2023). The effect can be characterised through its magnitude—by how much the neuronal response diminishes—and through its lifetime, the timespan over which the attenuating effect of previous stimulation persists.…”