Presentation
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Cortical representations for native and non-native phoneme perception
Poster C79 in Poster Session C, Wednesday, October 25, 10:15 am - 12:00 pm CEST, Espace Vieux-Port
Tzuyi Tseng1, Jennifer Krzonowski1, Alice C. Roy1, Claudio Brozzoli2, Véronique Boulenger1; 1Laboratoire Dynamique Du Langage, UMR 5596 CNRS - Université Lumière Lyon 2, Lyon, France, 2ImpAct team, Inserm, Centre de Recherche en Neurosciences de Lyon, Lyon, France
Converging evidence shows that speech perception induces activations of sensorimotor brain areas that are normally involved in speech production (Skipper et al., 2017; Franken et al., 2022, for reviews). This sensorimotor activity is particularly evident in noisy conditions and is somatotopically organized depending on the place of articulation of phonemes: listening to bilabial and dental consonants activates the motor representations of the lips and the tongue, respectively (Pulvermüller et al., 2006). Motor involvement in non-native phoneme perception has also been reported (Wilson & Iacoboni, 2006). Several studies however failed to replicate the somatotopic mapping of motor cortex in (native) speech perception (Arsenault & Buchsbaum, 2016), or showed premotor recruitment only when the degraded speech sounds became identifiable (Du et al. 2014; Osnes et al, 2011). The necessity and the role of the motor activation in processing non-/native and/or degraded/intact speech sounds therefore remain unclear. The current study aims to unravel how sensorimotor regions are activated as a function of the phonological distance between native and foreign phonemes under degraded or optimal perceptual conditions. We hypothesize that the activity in sensorimotor regions varies depending on the phonological proximity between non-native sounds with respect to the native phonological repertoire. To examine this sensorimotor organization, we run a combined behavioral and fMRI study. We recorded brain activity of twenty healthy French right-handed adults while they were listening to consonant-vowel syllables, embedding either native French consonants (/p/, /t/, /ʃ/, /ʁ/), or non-native Mandarin Chinese consonants (/pʰ/, /tʰ/, /ʂ/, /x/). While half of the syllables were masked with pink noise, the participants were required to identify the consonants as native or non-native by left hand button press. Only a single phonetic feature differentiates between consonants in three of the pairs (aspiration for /p-pʰ/ and /t-tʰ/, and tongue retroflection for /ʃ-ʂ/), whereas consonants in the fourth pair /ʁ-x/ differ on two features (voicing and place of articulation). Either intact or noisy non-native phonemes should trigger strong, though not well-circumscribed, premotor cortical activity. The phonological distance between French and Chinese consonants may however influence the activation pattern. Phonologically-close foreign phonemes (/pʰ/, /tʰ/, /ʂ/) may be processed as degraded versions of the native consonants, thus eliciting similar activity to their noisy native counterparts (/p/, /t/, /ʃ/). On the contrary, the more distant consonant /x/ may be identified as non-native and yield the strongest premotor activity. Preliminary behavioral results show significantly lower performance to identify the Chinese fricative /ʂ/ than the French /ʃ/; no differences between other consonant pairs were found. Preliminary fMRI univariate analyses against the baseline suggest stronger activation in the left inferior frontal cortex when identifying intact French consonants, and in the bilateral superior temporal cortex and the left premotor cortex for phonemes in both languages irrespective of noise. In the supplementary motor area, the activation is stronger for intact than noisy French and for noisy than intact Chinese consonants. As next steps, multivariate and connectivity analyses will allow to assess whether premotor-temporal connectivity varies depending on the phonological distance between native and non-native phonemes.
Topic Areas: Signed Language and Gesture, Multilingualism