Functional Heterogeneity of Voice-Encoding Cortex Revealed by Clinical Language Mapping

Regions in the superior temporal sulcus and gyrus have been heavily implicated in voice-selective responses in human auditory cortex. Despite an apparent specialization for the encoding of human voice, research outside the auditory domain suggests that these areas likely participate in additional neural processes including speech processing and production. The aim of the current study was to combine results of electrophysiological recording and clinical stimulation mapping procedures in patients undergoing stereoelectroencephalography (sEEG) to explore potential functional heterogeneity in voice-encoding cortex. Both channels that demonstrated voice-encoding properties and channels critically implicated in language functioning were heavily concentrated in the left STG/S. Analysis of functional overlap revealed channels in the posterior STG/S that appear to be involved in both voice encoding and language. Strength of voice encoding in these functionally diverse sites was not significantly different from sites that were implicated in voice encoding alone. Our findings add to prior observations of functional heterogeneity in the STG/S and contribute to proposed models of speech perception. We discuss these results in the context of the utility of electrophysiological methods in mapping cortical networks and identifying regions essential for functioning.