Functional subnetwork structure in auditory cortex for stream segregation

Abstract

Perceptual integration and segregation of alternating tone sequence differing in frequency (ABA-ABA-...) depend on the frequency differences (Delta-Fs) between A and B tones and the inter-tone intervals (ITIs) between successive tones. In the auditory cortex, tonotopic separation, forward suppression and multisecond habituation have been considered as possible neural correlates of this perceptual phenomenon. This model, however, cannot completely account for the van Noorden's perceptual boundary and the temporally continuous perception of auditory streaming. Here we examined the temporal changes of the functional network properties in auditory cortex to tone sequences with different Delta-Fs and ITIs. Specifically, we recorded local field potentials using microelectrode arrays from anesthetized and awake rats and constructed the functional network based on phase synchrony in gamma-band oscillation. As the results, the networks consisted of sub-networks highly correlated with tonotopy, and the sub-network selective to B tones lasted for a prolonged period at large Delta-F. Such characteristic substructures of functional network are a possible candidate of neural mechanisms of auditory stream segregation.