Biology subjects

Wallois, F.

Publications and source records attributed to Wallois, F..

5 recordsLinked to original sources

bioRxiv2026

A touch that lingers: synchronized patting strengthens neural tracking of auditory rhythm in newborns

Rhythmic auditory stimulation in early life rarely occurs in isolation. Caregivers naturally combine singing and speech with rhythmic touch, rocking, and visual cues. Newborns are sensitive to auditory rhythm from birth, yet little is known about how temporally aligned information across sensory modalities shapes the neural encoding of auditory rhythmic structure. Here, we tested whether rhythmic touch can alter how the newborn brain tracks an ongoing auditory signal beyond the period of tactile stimulation. We recorded high-density electroencephalography from full-term newborns (N = 40), 1-3 days after birth, while they were exposed to recorded French lullabies presented either alone or accompanied by gentle patting synchronized with the metrically strong beat. Patting was delivered intermittently, allowing us to compare neural responses to lullabies across conditions, notably during periods without concurrent tactile stimulation. We quantified neural tracking of the lullabies using brain-stimulus coherence and temporal response function modeling. Newborns' neural activity synchronized with the rhythmic structure of the lullabies at frequencies corresponding to both the beat and the metrically accented strong beat. Critically, neural tracking was stronger when the lullabies had been accompanied by synchronized touch than when they were presented alone, and this enhancement persisted during subsequent periods in which no touch was delivered. Although rhythmic touch enhanced tracking in newborns with both weaker and stronger auditory-only tracking, there was a larger gain in those who initially showed weaker auditory tracking. Together, our findings reveal that the newborn brain exploits rhythmic touch to strengthen its encoding of auditory rhythm, and that this benefit outlasts the touch itself. This provides neural evidence that patting an infant in time with a song, a caregiving practice shared across cultures, does more than simply provide a tactile stimulation. It shapes how the newborn brain encodes the song's rhythm.

neuroscience↗

bioRxiv2026

Effect of tempo on newborns' neural processing of auditory rhythm: Emergence of sensitivity to metrical structure

Rhythm perception ability underpins music and language processing, and its developmental origins trace back to the earliest periods of life. While most rhythm patterns contain a variety of inter-onset intervals, listeners typically extract a steady underlying beat periodicity, as well as beat grouping periodicities (groups of two or three beats will be at frequencies 1/2 or 1/3, respectively, of that of the primary beat), forming a metrical hierarchy. While the developing brain can track auditory rhythm before birth, a previous study found that neural sensitivity to faster beat-related periodicities emerges early in third trimester of gestation, whereas encoding of slower metrical structure periodicities only appears closer to term birth. However, as rhythm patterns were only presented at one tempo, neural sensitivity to metrical structure could not be disentangled from sensitivity to tempo during early development. Thus, here we presented auditory rhythmic sequences at two different tempi and used high-resolution electroencephalography to measure neural sensitivity to their encoding in full-term newborns and young adults. Adults demonstrated a similar sensitivity to metrical structure across tempi, with greatest response at the duple metrical frequency regardless of tempo. Newborn neural responses, by contrast, were tempo-dependent, displaying markedly different response patterns across beat and meter frequencies at the different tempi. Together, these results reveal that tempo and metrical structure interact in shaping how the neonatal brain encodes auditory rhythm, suggesting that early neural processing may be constrained in its ability to track slower periodicities, and highlighting a developmental shift in the relative contributions of tempo and metrical structure to rhythmic processing. Research HighlightsO_LIAdults show stable sensitivity to metrical structure across tempi, with peak responses at the duple level. C_LIO_LINewborns neural responses are tempo-dependent, showing distinct patterns across beat and metrical frequencies. C_LIO_LITempo and metrical structure jointly shape neural encoding of rhythm in the brain, revealing a developmental shift in their relative contributions. C_LI

neuroscience↗

bioRxiv2023

Detection of regularities in auditory sequences before and at term-age in human neonates

During the last trimester of gestation, fetuses and preterm neonates begin to respond to sensory stimulation and to discover the structure of their environment. Yet, neuronal migration is still ongoing. This late migration notably concerns the supra-granular layers neurons, which are believed to play a critical role in encoding predictions and detecting regularities. In order to gain a deeper understanding of how the brain processes and perceives regularities during this stage of development, we conducted a study in which we recorded event-related potentials (ERP) in 31-wGA preterm and full-term neonates exposed to alternating auditory sequences (e.g. "ba ga ba ga ba"), when the regularity of these sequences was violated by a repetition (e.g., "ba ga ba ga ga"). We compared the ERPs in this case to those obtained when violating a simple repetition pattern ("ga ga ga ga ga" vs "ga ga ga ga ba"). Our results indicated that both preterm and full-term neonates were able to detect violations of regularity in both types of sequences, indicating that as early as 31 weeks gestational age, human neonates are sensitive to the conditional statistics between successive auditory elements. Full-term neonates showed an early and similar mismatch response (MMR) in the repetition and alternating sequences. In contrast, 31-wGA neonates exhibited a two-component MMR. The first component which was only observed for simple sequences with repetition, corresponded to sensory adaptation. It was followed much later by a deviance-detection component that was observed for both alternation and repetition sequences. This pattern confirms that MMRs detected at the scalp may correspond to a dual cortical process and shows that deviance detection computed by higher-level regions accelerates dramatically with brain maturation during the last weeks of gestation to become indistinguishable from bottom-up sensory adaptation at term. HighlightsO_LIStarting at 31 wGA, neonates are sensitive to conditional statistics between successive events. C_LIO_LIThe MisMatch Response detected at the scalp may correspond to a dual cortical process C_LIO_LIThe prediction error signal accelerates during the third trimester of gestation C_LIO_LIIt overlaps with the phenomenon of sensory adaptation at term age C_LI

neuroscience↗

bioRxiv2023

Multiscale entropy analysis of combined EEG-fNIRS measurement in preterm neonates

In nature, biological systems such as the human brain are characterized by complex and non-linear dynamics. One way of quantifying signal complexity is Multiscale Entropy (MSE), which is suitable for structures with long-range correlation at different time scales. In developmental neuroscience, MSE can be taken as an index of brain maturation, and can differentiate between healthy and pathological development. In our current work, we explored the developmental trends of MSE on the basis of 30 simultaneous EEG - fNIRS recordings in premature infants between 27 and 34 weeks of gestational age (wGA). To explore potential factors impacting MSE, we determined the relation between MSE and the EEG Power Spectrum Density (PSD) and Spontaneous Activity Transients (SATs). As a result, via wGA, the MSE calculated on the EEG increases, thus reflecting the maturational processes in the brain networks, whereas in the fNIRS, MSE decreases, which might indicate a maturation of the brain blood supply. Moreover, we propose that the EEG power in the beta band (13-30 Hz) might be the main contributor to MSE in the EEG. Finally, we highlight the importance of SATs in determining MSE as calculated from the fNIRS recordings. HighlightsBiological systems show complex and non-linear dynamics. With Multiscale Entropy (MSE) we studied simultaneous EEG-fNIRS in premature infants. MSE in the EEG increases over gestational age, MSE in the fNIRS decreases. EEG power spectrum density and spontaneous activity transients contribute to MSE.

neuroscience↗

bioRxiv2022

Skull and scalp segmentation in neonatal cerebral MRI using subject-specific probability models

This study presents a new approach for segmenting cranial bones in magnetic resonance images (MRIs) acquired from neonates in the gestational age range of 39 to 42 weeks. the approach uses subject-specific probability maps of the skull and scalp, created from atlas computed tomography (CT) images taken retrospectively from neonates in the same age range. the method also uses a subject-specific probability map of cerebrospinal fluid (CSF), constructed from retrospective atlas MRIs. To build skull, scalp, and CSF probability maps, a subject-specific bimodal MR-CT neonatal head template is employed. In the next step, the subject-specific probability maps are fed to the expectation maximization algorithm in conjunction with Markov random field method implemented in FSL software to segment the skull and scalp from the input MR image. The results of the proposed method were evaluated through various experiments. First, we employed our method as a brain tissue extractor and compared its results with public methods such as the Brain Extraction Tool (BET) and Brain Surface Extractor (BSE). Second, we calculated the similarity in shape between the frontal and occipital sutures (which had been reconstructed from segmented cranial bones) and the ground truth. For this purpose, modified versions of the Dice similarity coefficient (DSC) were adopted and used. Finally, retrospective data including MRI and CT images obtained from the same neonate within a short time interval were used. After aligning the two images, the DSC and modified Hausdorff distance (MHD) were used to compare the similarity of the cranial bones in the MR and CT images. Furthermore, the anterior fontanel size was compared to the normal size reported for neonates in the same age range. Cranial bone thickness was calculated and compared to normal values reported for healthy neonates. The results of these experiments demonstrated the success of our segmentation method. The algorithm for creating subject-specific atlases is publicly accessible through a graphical user interface at medvispy.ee.kntu.ac.ir.

bioengineering↗