Biology subjects

Hertz-Pannier, L.

Publications and source records attributed to Hertz-Pannier, L..

6 recordsLinked to original sources

bioRxiv2025

Characterization of aperiodic and theta activity in preterm infants using EEG: Insights into cerebral maturation and inter-individual variability

Disrupting critical processes of brain development, preterm birth interferes with the maturation of brain networks and functional activity, including theta oscillations that are thought to play a key role in early network formation. Traditional EEG spectral analyses have indicated marked development of theta power in early infancy, but these approaches mix oscillatory and non-oscillatory activity, limiting insights into the mechanisms underlying the neural changes. Using spectral parameterization, we aimed to evaluate developmental changes in aperiodic activity and periodic theta power in infants born very preterm compared to full-terms, and to further explore whether clinical factors and brain microstructure could explain the inter-individual variability within preterms. High-density EEG was acquired during active/REM sleep at term-equivalent age (TEA) and 2 months corrected age (2mCA) in 41 very preterm infants (born <32 weeks gestational age [GA]; mean {+/-} standard deviation: 26.9{+/-}1.7 weeks) and 13 full-term controls (born [≥]37 weeks GA; 40.1{+/-}1 weeks). Spectral parameterization was used to extract aperiodic components (offset, exponent) and periodic theta power globally and across spatial clusters of electrodes (anterior, central, posterior). From TEA to 2mCA, offset, exponent, and theta power increased with no differences between preterm and full-term infants. At TEA, metrics of aperiodic activity were stronger in anterior compared with posterior areas, but this regional landscape shifted by 2mCA with pronounced increases in aperiodic offset and exponent in posterior areas from TEA to 2mCA. Within preterms, inter-individual variability in aperiodic and periodic activity at TEA was partly explained by clinical risk factors: male sex, lower gestational-age at birth, small weight at birth, and invasive ventilation were linked to alterations of aperiodic offset, exponent and theta power. Additionally, higher theta power at TEA correlated with lower cortical fractional anisotropy assessed with diffusion MRI at the same age, consistently with more advanced maturation of the brain. Collectively, these findings indicate that EEG spectral parameterization combined with spatial analysis provides a sensitive framework for characterizing the postnatal maturation of brain activity in infants, as well as early vulnerabilities associated with prematurity and perinatal adversity.

neuroscience↗

bioRxiv2025

Multimodal imaging of human fetal brain development at the mesoscopic scale using 11.7 T ex vivo MRI

We present the first release of p-HCP (Prenatal Human Connectome Patterns), an imaging dataset of human fetal brain development covering the second half of gestation. This dataset was acquired ex vivo using magnetic resonance imaging (MRI) at ultra high field (11.7 teslas), and includes whole-hemisphere T2-weighted images at 100 {micro}m isotropic resolution, quantitative relaxometry (T1, T2, and [Formula]), and high angular resolution diffusion-weighted images for multiple b-values at 200 {micro}m. Brains larger than the workspace of the small-bore scanner were sectioned into blocks, acquired blockwise, and digitally reconstructed using a dedicated semi-automatic method. This initial data release includes three gestational ages (18, 27, and 31 post-conceptional weeks) with a complete set of anatomical images, relaxometry maps, and diffusion-based microstructure measurements. This dataset offers new opportunities to investigate neurodevelopmental processes that have not yet been explored with full three-dimensional coverage at this resolution by MRI, and may serve as a multimodal mesoscopic reference template for the fetal brain.

neuroscience↗

bioRxiv2025

On the typical development of the central sulcus in infancy: a longitudinal evaluation of its morphology and link to behaviour

IntroductionThe progressive folding of the cortex is an important feature of neurodevelopment starting early during gestation. The central sulcus (CS) is one of the first to fold. Since it represents the anatomical boundary between primary somatosensory and motor functional regions, its developing morphology may inform on the acquisition of sensorimotor skills. We aimed to identify potential asynchronous morphological changes along the CS during infancy, with the hypothesis that this may reflect the gradual emergence of body usage. MethodBased on 3T anatomical magnetic resonance imaging (MRI) and dedicated post-processing, we characterized the evolution in CS depth and curvature in 33 typical infants (aged 1 and 3 months, 22 with longitudinal data) in relation to 23 young adults as a reference. Four regions of interest (ROIs) along the CS, supposed to correspond to different parts of the body and one centred on the hand knob (HK), were reproducibly examined and compared across groups. We also explored the relationship between the age-related changes in morphological features and the global motor scaled scores evaluated at 3 months of age with the Bayley Scales of Infant and Toddler Development. ResultsWhile all ROIs showed significant increases in CS depth and curvature between 3-month-olds and adults, the results were more variable between 1 and 3 months of age depending on cross-sectional and longitudinal analyses. The central-medial and central-lateral regions showed the most consistent increase in depth. Besides, motor development at 3 months of age was not significantly related to CS morphological changes, but a positive trend was observed for depth changes in the (HK-related) central-medial ROI. ConclusionThe rapid evolution of CS folding during infancy may reflect the intense but asynchronous maturation of the brain sensorimotor system, with the differential growth of cortical areas related to body parts and underlying white matter connections. Although it will have to be replicated on larger groups and at other ages, this longitudinal and multimodal study highlights the potential of characterizing CS features as key markers of early sensorimotor development, both at the cerebral and behavioural levels. Combining anatomical and functional neuroimaging could provide deeper insights into the relationship between CS morphology and somatotopic organization in typical infants, but also in infants at risk of developing motor disorders.

neuroscience↗

bioRxiv2024

Temporal dynamics and maturation of resting-state activity in preterm infants

By interfering with the normal sequence of mechanisms serving the brain maturation, premature birth and related stress can alter perinatal experiences, with potential long-term consequences on a childs neurodevelopment. The early characterization of brain functioning and maturational changes is thus of critical interest in premature infants who are at high risk of atypical outcomes and could benefit from early diagnosis and dedicated interventions. Using high-density electroencephalography (HD-EEG), we recorded brain activity in extreme and very preterm infants at the equivalent age of pregnancy term (n=43), and longitudinally 2-months later (n=33), compared with full-term born infants (n=14). We characterized the maturation of brain activity by using a dedicated microstate analysis to quantify the spatio-temporal dynamics of the spontaneous transient network activity while controlling for vigilance states. The comparison of premature and full-term infants first showed slower dynamics as well as altered spatio-temporal properties of brain activity in preterm infants. Maturation of functional networks between term-equivalent age and 2 months later in preterms was linked to the emergence of faster dynamics, manifested in part by shorter duration of microstates, as well as an evolution in the spatial organization of the dominant microstates. The inter-individual differences in the temporal dynamics of brain activity at term-equivalent age were further impacted by sex (with slower microstate dynamics in boys) and by gestational age at birth for some microstate dynamics but not by other considered risk factors. This study highlights the potential of the microstate approach to reveal maturational properties of the emerging brain network activity in premature infants.

neuroscience↗

bioRxiv2022

Early structural connectivity within the sensorimotor network: deviations related to prematurity and association to neurodevelopmental outcome

The sensorimotor (SM) network is crucial for optimal neurodevelopment. However, undergoing rapid maturation during the perinatal period, it is particularly vulnerable to preterm birth. Our work explores the prematurity impact on the microstructure and maturation of primary SM white matter (WM) tracts at term-equivalent age (TEA) and evaluates the relationships between these alterations and neurodevelopmental outcome. We analyzed diffusion MRI data from the developing Human Connectome Project (dHCP) database: 59 preterm (PT) low-risk infants scanned near TEA, compared to a control group of full-term (FT) neonates paired for age at MRI and sex. We dissected pairwise connections between primary SM cortices and subcortical structures using probabilistic tractography and evaluated their microstructure with diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) models. In addition to tract- specific univariate analyses of diffusion metrics, we computed a maturational distance related to prematurity based on a multi-parametric Mahalanobis distance of each PT infant relative to the FT group. Finally, we evaluated the relationships between this distance and Bayley Scales of Infant and Toddler Development (BSID-III) scaled scores at 18 months corrected age. Our results confirm important microstructural differences in SM tracts between PT and FT infants, with effects increasing with lower gestational age at birth. Additionally, comparisons of maturational distances highlight that prematurity has a differential effect on SM tracts which follows the established WM caudo-rostral developmental pattern. Our results suggest a particular vulnerability of projections involving the primary sensorimotor cortices (S1) and of the most rostral tracts, with cortico-cortical and S1-Lenticular tracts presenting the highest alterations at TEA. Finally, NODDI-derived maturational distances of specific tracts seem related to fine motor and cognitive scores. This study expands the understanding of the impact of early WM alterations in the emerging SM network on long-term neurodevelopment. In the future, related approaches have potential to lead to the development of neuroimaging markers for neurodevelopmental disorders, with special interest for subtle neuromotor impairments frequently observed in preterm-born children.

neuroscience↗

bioRxiv2020

A Connectome-Based Approach to Assess Motor Outcome after Neonatal Arterial Ischemic Stroke

Objectivestudies of motor outcome after Neonatal Arterial Ischemic Stroke (NAIS) often rely on lesion mapping using MRI. However, clinical measurements indicate that motor deficit can be different than what would solely be anticipated by the lesion extent and location. Because this may be explained by the cortical disconnections between motor areas due to necrosis following the stroke, the investigation of the motor network can help in the understanding of visual inspection and outcome discrepancy. In this study, we propose to examine the structural connectivity between motor areas in NAIS patients compared to healthy controls in order to define the cortical and subcortical connections that can reflect the motor outcome Methods30 healthy controls and 32 NAIS patients with and without Cerebral Palsy (CP) underwent MRI acquisition and manual assessment. The connectome of all participants was obtained from T1-weighted and diffusion-weighted imaging. Resultssignificant disconnections in the lesioned and contra-lesioned hemispheres of patients were found. Furthermore, significant correlations were detected between the structural connectivity metric of specific motor areas and manuality assessed by the Box and Block Test (BBT) scores in patients. Interpretationusing the connectivity measures of these links the BBT score can be estimated using a multiple linear regression model. In addition, the presence or not of CP can also be predicted using the KNN classification algorithm. According to our results, the structural connectome can be an asset in the estimation of gross manual dexterity and can help uncover structural changes between brain regions related to NAIS.

bioengineering↗