Neuronal responses to omitted tones in the auditory brain: A neuronal correlate for predictive coding

Abstract

Prediction provides key advantages for survival, and cognitive studies have demonstrated that the brain com- putes multilevel predictions. Evidence for predictions remains elusive at the neuronal level because of the com- plexity of separating neural activity into predictions and stimulus responses. We overcome this challenge by recording from single neurons from cortical and subcortical auditory regions in anesthetized and awake prep- arations, during unexpected stimulus omissions interspersed in a regular sequence of tones. We find a subset of neurons that responds reliably to omitted tones. In awake animals, omission responses are similar to anesthe- tized animals, but larger and more frequent, indicating that the arousal and attentional state levels affect the degree to which predictions are neuronally represented. Omission-sensitive neurons also responded to frequen- cy deviants, with their omission responses getting emphasized in the awake state. Because omission responses occur in the absence of sensory input, they provide solid and empirical evidence for the implementation of a predictive process.