The sound of silence: Omission responses and how the brain predicts in the absence of sound

Abstract

[EN]Omission responses have been proposed as neural signatures of predictive coding mechanisms that arise when expected sensory events fail to occur. These responses support the view that the brain actively generates and updates internal models to anticipate future events, rather than passively processing incoming sensory input. Importantly, omission responses offer a direct index of prediction error and prediction. They are modulated by the behavioral relevance and predictability of the omitted stimulus. Emerging studies have shown that omission responses occur across a range of auditory paradigms and involve complex interactions between excitatory and inhibitory neurons, particularly via feedforward inhibition of pyramidal cells by specific interneuron populations. When an anticipated stimulus is omitted, the resulting disinhibition of pyramidal neurons generates a prediction error signal; crucial for updating internal models and driving synaptic plasticity. This mechanism shares key features with mismatch negativity and corollary discharge, suggesting that overlapping cortical circuits are engaged in predictive processing. Taken together, these findings highlight the value of omission responses as electrophysiological markers of the brain's active prediction and prediction error signaling in auditory perception.