Neural Substrates of Phonemic Perception

TLDR

The left temporal lobe is known to be involved in speech sound perception, but the distinct roles of its subregions in processing speech signals remain unclear. We found that the left middle/anterior superior temporal sulcus preferentially responds to familiar consonant–vowel syllables, indicating it mediates phonemic perception by linking primary auditory analysis in dorsal STG to higher‑level linguistic processing.

Abstract

The temporal lobe in the left hemisphere has long been implicated in the perception of speech sounds. Little is known, however, regarding the specific function of different temporal regions in the analysis of the speech signal. Here we show that an area extending along the left middle and anterior superior temporal sulcus (STS) is more responsive to familiar consonant–vowel syllables during an auditory discrimination task than to comparably complex auditory patterns that cannot be associated with learned phonemic categories. In contrast, areas in the dorsal superior temporal gyrus bilaterally, closer to primary auditory cortex, are activated to the same extent by the phonemic and nonphonemic sounds. Thus, the left middle/anterior STS appears to play a role in phonemic perception. It may represent an intermediate stage of processing in a functional pathway linking areas in the bilateral dorsal superior temporal gyrus, presumably involved in the analysis of physical features of speech and other complex non-speech sounds, to areas in the left anterior STS and middle temporal gyrus that are engaged in higher-level linguistic processes.