Biology subjects

Lizarazu, M.

Publications and source records attributed to Lizarazu, M..

9 recordsLinked to original sources

bioRxiv2026

Modulating Neural Tracking of Speech in Infants

Neural oscillations synchronize to the rhythmic structure of speech, a process known as cortical tracking that is thought to support speech perception and language acquisition. Individual differences in cortical tracking during infancy predict later language outcomes, yet little is known about whether this neural mechanism can be shaped by recent auditory experience early in development. Here, we tested whether brief exposure to structured musical rhythms modulates cortical tracking of speech in Spanish-Basque bilingual infants at 6 and 10 months of age. Infants listened to speech preceded by either temporally regular musical sequences that mirrored the rhythmic structure of the speech signal or rhythmically irregular musical sequences. Cortical tracking was measured using electroencephalography and quantified as speech-brain coherence in the delta and theta frequency bands. Regular musical sequences enhanced subsequent cortical tracking of speech, but the effects varied across age, language, and frequency band. In Spanish, rhythmic priming enhanced delta-band tracking at 10 months of age, whereas in Basque it enhanced theta-band tracking at both 6 and 10 months. These language-specific effects suggest that rhythmic priming interacts with the temporal properties of individual languages and infants developing linguistic experience. Together, the findings demonstrate that cortical tracking is a highly flexible neural mechanism during infancy and can be rapidly modulated by structured rhythmic input. Thus, we identify rhythmic experience as a potential pathway through which infants auditory environment shapes neural speech processing during language development.

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↗

bioRxiv2024

Cortical tracking of speech is reduced in adults who stutter when listening for speaking

PurposeInvestigate cortical tracking of speech (CTS) in adults who stutter (AWS) compared to typically fluent adults (TFA) to test the involvement of the speech-motor network in tracking auditory information. MethodParticipants EEG was recorded while they either had to simply listen to sentences (listening only) or complete them by naming a picture (listening-for-speaking), thus manipulating the upcoming involvement of speech production. We analyzed speech-brain coherence and brain connectivity during listening. ResultsDuring the listening-for-speaking task, AWS exhibited reduced CTS in the 3-5 Hz range (theta), corresponding to the syllabic rhythm. The effect was localized in left inferior parietal and right pre-/supplementary motor regions. Connectivity analyses revealed that TFA had stronger information transfer in the theta range in both tasks in fronto-temporo-parietal regions. When considering the whole sample of participants, increased connectivity from the right superior temporal cortex to the left sensorimotor cortex was correlated with faster naming times in the listening-for-speaking task. ConclusionsAtypical speech-motor functioning in stuttering also impacts speech perception, especially in situations requiring articulatory alertness. The involvement of frontal and (pre-) motor regions in CTS in typically fluent adults is highlighted. Speech perception in individuals with speech-motor deficits should be further investigated, especially when smooth transitioning between listening and speaking is required, such as in real-life conversational settings.

neuroscience↗

bioRxiv2023

The contribution of early language exposure to the cortical tracking of speech

Cortical tracking of speech is relevant for the development of speech perception skills. However, no study to date has explored whether and how cortical tracking of speech is shaped by accumulated language experience, the central question of this study. In 35 bilingual children (6 y.o.) with considerably bigger experience in one language, we collected electroencephalography data while they listened to continuous speech in their two languages. Cortical tracking of speech was assessed at acoustic-temporal and lexico-semantic levels. Children showed more robust acoustic-temporal tracking in the least experienced language, and more sensitive cortical tracking of semantic information in the most experienced language. Additionally, and only for the most experienced language, acoustic-temporal tracking was specifically linked to phonological abilities, and lexico-semantic tracking to vocabulary knowledge. Our results indicate that accumulated linguistic experience is a relevant maturational factor for the cortical tracking of speech at different levels during early language acquisition.

neuroscience↗

bioRxiv2023

Language experience shapes predictive coding of rhythmic sound sequences

Perceptual systems heavily rely on prior knowledge and predictions to make sense of the environment. Predictions can originate from multiple sources of information, including contextual short-term priors, based on isolated temporal situations, and context-independent long-term priors, arising from extended exposure to statistical regularities. While the effects of short-term predictions on auditory perception have been well-documented, how long-term predictions shape early auditory processing is poorly understood. To address this, we recorded magnetoencephalography data from native speakers of two languages with different word orders (Spanish: functor-initial versus Basque: functor-final) listening to simple sequences of binary sounds alternating in duration with occasional omissions. We hypothesized that, together with contextual transition probabilities, the auditory system uses the characteristic prosodic cues (duration) associated with the native languages word order as an internal model to generate long-term predictions about incoming non-linguistic sounds. Consistent with our hypothesis, we found that the amplitude of the mismatch negativity elicited by sound omissions varied orthogonally depending on the speakers linguistic background and was most pronounced in the left auditory cortex. Importantly, listening to binary sounds alternating in pitch instead of duration did not yield group differences, confirming that the above results were driven by the hypothesized long-term "duration" prior. These findings show that experience with a given language can shape a fundamental aspect of human perception - the neural processing of rhythmic sounds - and provides direct evidence for a long-term predictive coding system in the auditory cortex that uses auditory schemes learned over a lifetime to process incoming sound sequences.

neuroscience↗

bioRxiv2021

Reading-related brain changes in audiovisual processing: cross-sectional and longitudinal MEG evidence

The ability to establish associations between visual objects and speech sounds is essential for human reading. Understanding the neural adjustments required for acquisition of these arbitrary audiovisual associations can shed light on fundamental reading mechanisms and help reveal how literacy builds on pre-existing brain circuits. To address these questions, the present longitudinal and cross-sectional MEG studies characterize the temporal and spatial neural correlates of audiovisual syllable congruency in children (4-9 years old, 22 males and 20 females) learning to read. Both studies showed that during the first years of reading instruction children gradually set up audiovisual correspondences between letters and speech sounds, which can be detected within the first 400 ms of a bimodal presentation and recruit the superior portions of the left temporal cortex. These findings suggest that children progressively change the way they treat audiovisual syllables as a function of their reading experience. This reading-specific brain plasticity implies (partial) recruitment of pre-existing brain circuits for audiovisual analysis. Significance StatementLinking visual and auditory linguistic representations is the basis for the development of efficient reading, while dysfunctional audiovisual letter processing predicts future reading disorders. Our developmental MEG project included a longitudinal and a cross-sectional study; both studies showed that childrens audiovisual brain circuits progressively change as a function of reading experience. They also revealed an exceptional degree of neuroplasticity in audiovisual neural networks, showing that as children develop literacy, the brain progressively adapts so as to better detect new correspondences between letters and speech sounds.

neuroscience↗

bioRxiv2021

Real-Time EEG Neurofeedback as a Tool to Improve Neural Entrainment to Speech

Neurofeedback represents a particular type of biofeedback whose aim is to teach self-control of brain function by measuring brain activity and presenting a feedback signal in real-time. Traditionally, neurofeedback has been used to complement interventions for various neuropsychological disorders through techniques like frequency training, which attempts to change the power ratio of certain EEG frequency bands. However, to date, there are no neurofeedback approaches that look directly into modulating the neural entrainment to speech. Speech-brain entrainment, which stands for the alignment of the neural activity to the envelope of the speech input, has been shown to be key to speech comprehension. In fact, atypical neural entrainment to speech seems to be consistently found in language development disorders such as dyslexia. Thus, making speech entrainment neurofeedback a promising technique to obtain behavioral improvements. In this work, we present the first open-source brain-computer interface system that can be reliably used to provide speech entrainment neurofeedback while still being flexible enough to deliver more traditional coherence-based neurofeedback. In addition, it has the potential of being an open-source alternative to deliver other types of neurofeedback if configured to do so.

bioengineering↗

bioRxiv2020

Temporal uncertainty affects the visual processing of predicted stimulus properties

Predictive processing has been proposed as a fundamental cognitive mechanism to account for how the brain interacts with the external environment via its sensory systems. In vision, contextual information triggers predictions about the content ("what") of environmental stimuli to update an internal generative model of the surrounding world. However, visual information dynamically changes across time, and temporal predictability ("when") may influence the impact of internal predictions on visual processing. In this magnetoencephalography (MEG) study, we investigated how processing feature specific information ("what") is affected by temporal predictability ("when"). In line with previous findings, we observed suppression of evoked neural responses in the visual cortex for predictable stimuli. Interestingly, we found that temporal uncertainty increased expectation suppression. This suggests that in temporally uncertain scenarios the neurocognitive system invests less resources in integrating bottom-up information. Multivariate pattern analysis showed that predictable visual features could be decoded from neural responses. Temporal uncertainty did not affect decoding accuracy for early visual responses, with the feature specificity of early visual neural activity preserved across conditions. However, decoding accuracy was less sustained over time for temporally jittered than for isochronous predictable visual stimuli. These findings converge to suggest that the cognitive system processes visual features of temporally predictable stimuli in higher detail, while processing temporally uncertain stimuli may rely more heavily on abstract internal expectations.

neuroscience↗

bioRxiv2019

Neocortical activity tracks syllable and phrasal structure of self-produced speech

To gain novel insights into how the human brain processes self-produced auditory information during reading aloud, we investigated the coupling between neuromagnetic activity and the temporal envelope of the heard speech sounds (i.e., speech brain tracking) in a group of adults who 1) read a text aloud, 2) listened to a recording of their own speech (i.e., playback), and 3) listened to another speech recording. Coherence analyses revealed that, during reading aloud, the readers brain tracked the slow temporal fluctuations of the speech output. Specifically, auditory cortices tracked phrasal structure (<1 Hz) but to a lesser extent than during the two speech listening conditions. Also, the tracking of syllable structure (4-8 Hz) occurred at parietal opercula during reading aloud and at auditory cortices during listening. Directionality analyses based on renormalized partial directed coherence revealed that speech brain tracking at <1 Hz and 4-8 Hz is dominated by speech-to-brain directional coupling during both reading aloud and listening, meaning that speech brain tracking mainly entails auditory feedback processing. Nevertheless, brain-to-speech directional coupling at 4- 8 Hz was enhanced during reading aloud compared with listening, likely reflecting speech monitoring before production. Altogether, these data bring novel insights into how auditory verbal information is tracked by the human brain during perception and self-generation of connected speech.\n\nHighlightsO_LIThe brain tracks phrasal and syllabic rhythmicity of self-produced (read) speech.\nC_LIO_LITracking of phrasal structures is attenuated during reading compared with listening.\nC_LIO_LISpeech rhythmicity mainly drives brain activity during reading and listening.\nC_LIO_LIBrain activity drives syllabic rhythmicity more during reading than listening.\nC_LI

neuroscience↗