Biology subjects

Kalashnikova, M.

Publications and source records attributed to Kalashnikova, M..

3 recordsLinked to original sources

bioRxiv2024

Are you talking to me? How the choice of speech register impacts listeners' hierarchical encoding of speech.

Speakers accommodate their speech to meet the needs of their listeners, producing different speech registers. One such register is Foreigner-Directed Speech (FDS), which is the way native speakers address non-native listeners, typically characterized by features such as slow speech rate and phonetic exaggeration. Here, we investigated how register impacts the cortical encoding of speech at different levels of language integration. Specifically, we tested the hypothesis that enhanced comprehension of FDS compared with Native-Directed Speech (NDS) involves more than just a slower speech rate, influencing speech processing from acoustic to semantic levels. Electroencephalography (EEG) signals were recorded from Spanish native listeners, who were learning English (L2 learners), and English native listeners (L1 listeners) as they were presented with audio-stories. Speech was presented in English in three different speech registers: FDS, NDS and a control register (Slow-NDS) which is slowed down version of NDS. We measured the cortical tracking of acoustic, phonological, and semantic information with a multivariate temporal response function analysis (TRF) on the EEG signals. We found that FDS promoted L2 learners cortical encoding at all the levels of speech and language processing considered. First, FDS led to a more pronounced encoding of the speech envelope. Second, phonological encoding was more refined when listening to FDS, with phoneme perception getting closer to that of L1 listeners. Finally, FDS also enhanced the TRF- N400, a neural signature of lexical expectations. Conversely FDS impacted acoustic but not linguistic speech encoding in L1 listeners. Taken together, these results support our hypothesis that FDS accommodates speech processing in L2 listeners beyond what can be achieved by simply speaking slowly, impacting the cortical encoding of sound and language at different abstraction levels. In turn, this study provides objective metrics that are sensitive to the impact of register on the hierarchical encoding of speech, which could be extended to other registers and cohorts.

neuroscience↗

bioRxiv2024

Temporal Structure of Music Improves the Cortical Encoding of Speech

Long and short-term musical training has been proposed to improve efficiency of cortical tracking of speech, the mechanism through which brain oscillations synchronize to the acoustic temporal structure of external stimuli. Here, we study how different rhythm structures of the musical signal can guide the temporal dynamics of auditory oscillations phase-aligned to the speech envelope. For this purpose, we investigated the effects of prior exposure to rhythmically structured musical sequences on cortical tracking of speech in Basque-Spanish bilingual adults. We conducted two EEG experiments where participants were presented with sentences in Basque and Spanish preceded by musical sequences that differed in their beat structure. The beat structure of the musical sequences was created to 1) reflect and match the syllabic structure of the sentences, 2) reflect a regular rhythm but not match the syllabic structure of the sentences, and 3) follow an irregular rhythm. First, we showed that the regularity found in the rhythmic structure of music acts as a temporal guide for brain oscillations. Second, our findings suggest that not only the regularity in music is crucial but so is adjusting this regularity to optimally reflect the rhythmic characteristics of the language. Third, despite finding some differences across frequencies for each language, we still found a strong effect of rhythm regularity on cortical tracking of speech. We showed that rhythm, inherent in musical signals, guides the adaptation of brain oscillations, by adapting the temporal dynamics of the oscillatory activity to the rhythmic scaffolding of the musical signal.

neuroscience↗

bioRxiv2022

Atypical cortical encoding of speech identifies children with Dyslexia versus Developmental Language Disorder

Slow cortical oscillations play a crucial role in processing the speech envelope, which is perceived atypically by children with Developmental Language Disorder (DLD) and developmental dyslexia. Here we use electroencephalography (EEG) and natural speech listening paradigms to identify neural processing patterns that characterize dyslexic versus DLD children. Using a story listening paradigm, we show that atypical power dynamics and phase-amplitude coupling between delta and theta oscillations characterize dyslexic and DLD children groups, respectively. We further identify EEG common spatial patterns (CSP) during speech listening across delta, theta and beta oscillations describing dyslexic versus DLD children. A linear classifier using four deltaband CSP variables predicted dyslexia status (0.77 AUC). Crucially, these spatial patterns also identified children with dyslexia in a rhythmic syllable task EEG, suggesting a core developmental deficit in neural processing of speech rhythm. These findings suggest that there are distinct atypical neurocognitive mechanisms underlying dyslexia and DLD.

neuroscience↗