Silent lipreading and covert speech production suppress processing of non-linguistic sounds in auditory cortex

Abstract

ABSTRACT

Auditory cortical deactivation during speech production and following speech perception: an EEG investigation of the temporal dynamics of the auditory alpha rhythm

“…As no overt production took place during the discrimination conditions, it may seem surprising that the auditory cluster should demonstrate α ERS during covert rehearsal as the observed auditory suppression is thought to be contingent on efference copy delivery linked to motor plan execution. These findings are not without precedent, however, as lip-reading (Kauramäki et al, 2010 ; Balk et al, 2013 ) and covert speech (Tian and Poeppel, 2015 ) have been shown to reduce auditory cortical responses. There is also evidence that failure of this sensory suppression in covert productions may be associated with some of the positive symptoms (i.e., auditory hallucinations) of schizophrenia (Ford et al, 2001 ; Ford and Mathalon, 2004 , 2005 ), indicating that auditory suppression during covert production is critical to normal function.…”

Shared and modality-specific brain regions that mediate auditory and visual word comprehension

“…Yet, most studies have focused on mapping activation strength rather than the encoding of word identity by cerebral speech representations. Hence, it could be that visual speech may activate many regions in an unspecific manner, without engaging specific semantic or lexical representations, maybe as a result of attentional engagement or feed-back ( Balk et al, 2013 ; Ozker et al, 2018 ). Support for this interpretation comes from lip reading studies showing that auditory cortical areas are equally activated by visual words and pseudo-words ( Calvert, 1997 ; Paulesu et al, 2003 ), and studies demonstrating cross-modal activations in early sensory regions also for simplistic stimuli ( Ferraro et al, 2020 ; Ibrahim et al, 2016 ; Petro et al, 2017 ).…”

Visual speech gestures modulate efferent auditory system

“…Their¯ndings revealed that observing visual speech gestures suppressed the auditory-cortex processing of the noise bursts only at the critical frequency band for speech processing compared to the control non-speech condition. The suppression activity was focused in the left hemisphere's¯rst transverse sulcus and the right hemisphere's superior temporal gyrus lateral to Heschl's sulcus (Balk et al, 2013). Similarly, in a magnetoencephalography study (Kauramäki et al, 2010), 100 ms (N100/N100 m) responses from the auditory-cortex were suppressed in the lipreading and covert speech production tasks relative to baseline and visual control tasks.…”

“…Visual speech gestures interact with the auditory system to modulate speech perception at both cortical and subcortical levels (Balk et al, 2013;Musacchia et al, 2006). Visual actions have been shown to modulate activity both in the primary and secondary auditory cortices (Calvert et al, 1997;Pekkola et al, 2005).…”

“…Given the active inhibitory e®ects of visual speech gestures on the auditory cortex (Balk et al, 2013;Kauramäki et al, 2010), we hypothesize a cortically mediated increase in MOC activity (i.e., increase in suppression) at the level of cochlea while observing visual speech relative to visual non-speech gestures. We investigated this using the CS-OAE paradigm; the descending cortical in°uences on MOC activity were indirectly assessed by examining the e®ects of CS on transient-evoked otoacoustic emissions (TEOAEs) under three conditions: (a) in the absence of any contralateral noise (Baseline or BL), (b) contralateral noise þ visually observing speech gestures related to productions of vowels /a/ and /u/ (AU) and (c) contralateral noise þ visually observing non-speech gestures related to smiling and frowning (SF).…”