Automatic phoneme category selectivity in the dorsal auditory stream

Mark A. Chevillet, Xiong Jiang, Josef P. Rauschecker, Maximilian Riesenhuber*

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    48 Citations (Scopus)

    Abstract

    Debates about motor theories of speech perception have recently been reignited by a burst of reports implicating premotor cortex (PMC) in speech perception. Often, however, these debates conflate perceptual and decision processes. Evidence that PMC activity correlates with task difficulty and subject performance suggests that PMC might be recruited, in certain cases, to acilitate category judgments about speech sounds (rather than speech perception, which involves decoding of sounds). However, it remains unclear whether PMC does, indeed, exhibit neural selectivity that is relevant for speech decisions. Further, it is unknown whether PMC activity in such cases reflects input via the dorsal or ventral auditory pathway, and whether PMC processing of speech is automatic or task-dependent. In a novel modified categorization paradigm, we presented human subjects with paired speech sounds from a phonetic continuum but diverted their attention from phoneme category using a challenging dichotic listening task. Using fMRI rapid adaptation to probe neural selectivity, we observed acoustic-phonetic selectivity in left anterior and left posterior auditory cortical regions. Conversely, we observed phoneme-category selectivity in left PMC that correlated with explicit phoneme-categorization performance measured after scanning, suggesting that PMC recruitment can account for performance on phoneme-categorization tasks. Structural equation modeling revealed connectivity from posterior, but not anterior, auditory cortex to PMC, suggesting a dorsal route for auditory input to PMC. Our results provide evidence for an account of speech processing in which the dorsal stream mediates automatic sensorimotor integration of speech and may be recruited to support speech decision tasks.

    Original languageEnglish
    Pages (from-to)5208-5215
    Number of pages8
    JournalJOURNAL OF NEUROSCIENCE
    Volume33
    Issue number12
    DOIs
    Publication statusPublished - 20 Mar 2013
    MoE publication typeA1 Journal article-refereed

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