Biology subjects

Bednaya, E.

Publications and source records attributed to Bednaya, E..

3 recordsLinked to original sources

bioRxiv2024

Resilience and vulnerability of speech neural tracking to early auditory deprivation

Infants are born with biological biases that favour language acquisition. One is the auditory systems ability to track the envelope of continuous speech, a pivotal feature for spoken language comprehension in adulthood. However, the extent to which neural speech tracking relies on postnatal auditory experience remains unknown. In this case-control study, we tested children with or without access to functional hearing in the first year of life after they received cochlear implants (CIs) for hearing restoration. We measured neural speech tracking in CI users with a congenital bilateral profound deafness (CD) or who acquired it later in development (AD; minimum auditory experience after birth 12 months), as well as in two groups of hearing controls listening to original (HC) or vocoded-speech (HC-v). Remarkably, neural speech tracking in children with CIs was unaffected by the absence of perinatal auditory experience. Regardless of deafness onset, CI users and HC exhibited a similar neural tracking magnitude at short timescales [~]50- 130 ms (P1TRF) of brain activity. However, this neural tracking phase (P1TRF) was delayed in CI users, and its timing depended on the age of hearing restoration. Conversely, at longer timescales [~]130-260 ms (N2TRF) of brain activity, speech tracking was substantially dampened in participants with CIs, thereby accounting for their comprehension deficits. Speech tracking in HC listening to vocoded-speech and in a phantom head-model with CIs suggested that neural processing differences between HC and CI children could not merely be explained by the degraded acoustic stimulation, nor by electrical artifacts of the implants. These findings highlight (i) the resilience of sensory components of neural speech tracking to the lack of hearing in the first year of life, (ii) the crucial role played when hearing restoration takes place in mitigating the impact of atypical auditory experience, (iii) the vulnerability of higher hierarchical levels of speech processing in CI users.

neuroscience↗

bioRxiv2024

The impact of face masks on face-to-face neural tracking of speech: auditory and visual obstacles

Face masks provide fundamental protection against the transmission of respiratory viruses but hamper communication. We estimated auditory and visual obstacles generated by face masks on communication by measuring the neural tracking of face-to-face speech. To this end, we recorded the EEG while participants were exposed to naturalistic audio-visual speech, embedded in multi-talker noise, in three contexts: (i) no-mask (audio-visual information was fully available), (ii) virtual mask (occluded lips, but intact audio), and (iii) real mask (occluded lips and degraded audio). The neural tracking of lip movements and the sound envelope of speech was measured through backward modeling, that is, by reconstructing stimulus properties from neural activity. Behaviorally, face masks increased listening -phonological-errors in speech content retrieval and perceived listening difficulty. At the neural level, we observed that the occlusion of the mouth abolished lip tracking and dampened neural tracking of the speech envelope at the earliest processing stages. Degraded acoustic information due to face mask filtering altered neural tracking at later processing stages instead. Finally, a consistent link emerged between the increment of listening perceived difficulty and the drop in reconstruction performance of speech envelope when attending to a speaker wearing a face mask. Results clearly dissociated the visual and auditory impacts of face masks on face-to-face neural tracking of speech. While face masks hampered the ability to predict and integrate audio-visual speech, the auditory filter generated by face masks impacted the neural processing stages typically associated with auditory selective attention. The link between perceived difficulty and neural tracking drop provided evidence of a major impact of face masks on the metacognitive levels subtending speech processing.

neuroscience↗

bioRxiv2022

Early visual cortex tracks speech envelope in the absence of visual input

Neural entrainment to continuous speech is typically observed within the language network and can be modulated by both low-level acoustic features and high-level meaningful linguistic units (e.g., phonemes, phrases, and sentences). Recent evidence showed that visual cortex may entrain to speech envelope, however its putative role in the hierarchy of speech processing remains unknown. We tested blindfolded participants who listened to semantically meaningful or meaningless stories, either in quiet or embedded in multi-talker babble noise. Entrainment to speech was assessed with forward linear modeling of participants EEG activity. We investigated (1) low-level acoustic effects by contrasting neural tracking of speech presented in quiet or noise and (2) high-level linguistic effects by contrasting neural tracking to meaningful or meaningless stories. Results showed that envelope tracking was enhanced and delayed for speech embedded in noise compared to quiet. When semantic information was missing, entrainment to speech envelope was fastened and reduced. Source modeling revealed that envelope tracking engaged wide neural networks beyond the auditory cortex, including early visual cortex. Surprisingly, while no clear influence of semantic content was found, the magnitude of visual cortex entrainment was affected by low-level features. The decrease of sound SNR-level dampened visual cortex tracking, suggesting an active suppressing mechanism in challenging listening conditions. Altogether, these findings provide further evidence of a functional role of early visual cortex in the entrainment to continuous speech.

neuroscience↗