Modeling and MEG evidence of early consonance processing in auditory cortex.

Abstract

Pitch is a fundamental attribute of auditory perception. The interaction of concurrentpitches gives rise to a sensation that can be characterized by its degree of consonance ordissonance. In this work, we propose that human auditory cortex (AC) processes pitchand consonance through a common neural network mechanism operating at earlycortical levels. First, we developed a new model of neural ensembles incorporatingrealistic neuronal and synaptic parameters to assess pitch processing mechanisms atearly stages of AC. Next, we designed a magnetoencephalography (MEG) experiment tomeasure the neuromagnetic activity evoked by dyads with varying degrees ofconsonance or dissonance. MEG results show that dissonant dyads evoke a pitch onsetFebruary 15, 20191/44 response (POR) with a latency up to 36 ms longer than consonant dyads. Additionally,we used the model to predict the processing time of concurrent pitches; here, consonantpitch combinations were decoded faster than dissonant combinations, in line with theexperimental observations. Specifically, we found a striking match between thepredicted and the observed latency of the POR as elicited by the dyads. These novelresults suggest that consonance processing starts early in human auditory cortex andmay share the network mechanisms that are responsible for (single) pitch processing.