Biology subjects

Cabaraux, P.

Publications and source records attributed to Cabaraux, P..

5 recordsLinked to original sources

bioRxiv2026

Temporal structure of postural sway reveals altered cortical postural coupling in aging and stroke: insights from nonlinear dynamics and state-space analysis

BackgroundBalance maintenance in humans is not only a mechanical process, but it also relies on continuous interactions between cortical activity and body dynamics. Alterations in postural sway are commonly observed in aging and stroke and are frequently used to assess balance impairment. However, similar balance deficits do not necessarily reflect similar underlying sensorimotor control mechanisms. Therefore, investigating brain-body interactions and their relationship to characteristics of postural behavior may provide deeper insights into the neural processes underlying balance dysfunction in these populations. ObjectiveTo determine whether brain-body coupling is associated with characteristics of postural behavior captured by the temporal organization of postural fluctuations beyond conventional magnitude-based measures of postural sway, and whether these relationships differ between stroke survivors, healthy older adults, and young adults. MethodsEEG and center-of-pressure (CoP) signals were recorded simultaneously in stroke survivors (n = 12), healthy older adults (n = 18), and young controls (n = 17) during quiet standing under 4 different manipulated sensory conditions. Sway-based corticokinematic coherence (CKC) as well as linear and nonlinear features (sample entropy, SE; fractal dimension, FD) of CoP were extracted. Linear mixed-effects model assessed associations between features and CKC, and model performance was compared using Akaike Information Criterion. Multidimensional state vectors were constructed from CKC, linear and nonlinear CoP features, and Euclidean distances between consecutive states in the standardized feature space were computed to quantify condition-dependent transitions in brain-body control organization. ResultsNonlinear features showed significant, group- and feature-dependent associations with CKC in the mediolateral direction, driven by significant SE and FD effects in the stroke group and an SE effect in the older group, while no significant associations were observed in the young group. Including nonlinear features in baseline models containing only linear CoP features significantly improved model fit. CKC alone showed low classification performance (AUC 50 to 65), whereas combining CKC with linear and nonlinear features improved group discrimination (AUC up to 0.86). State-space transition analysis revealed larger condition-dependent transitions in stroke participants compared with healthy older adults, particularly going from eyes open to eyes closed when standing on foam. ConclusionBrain-body coupling during standing may be understood more comprehensively by factoring in the temporal structure of fluctuations rather than their amplitude alone. These findings support the use of nonlinear dynamical features, combined with CKC, as potential markers of balance impairment.

neuroscience↗

bioRxiv2026

Assessment of sensorimotor cortical beta oscillations from peripheral electromyography and force recordings

The beta oscillations of the human primary sensorimotor cortex (SM1) play a crucial role in regulating motor and cognitive behavior in health and disease. However, their assessment relies on costly and complex neuroimaging techniques, limiting scalability and translational applications. We present a novel method for assessing beta oscillations from easily obtained peripheral electromyography and force recordings. We show that movement-induced modulations in SM1 beta oscillations can be assessed from the electromyography or force recordings of a contracted contralateral hand muscle. We demonstrate the fidelity of this method in young and elderly healthy participants and in Parkinsons disease patients. We also demonstrate that the resting-state SM1 beta interhemispheric coupling can be assessed from an interhand coupling between the electromyography or force of contracted homologous hand muscles. This methodology enables scalable and cost-effective investigations of beta oscillations for all fields of human neuroscience and for the development of accessible disease/therapeutic markers.

neuroscience↗

bioRxiv2026

Cortical involvement in stroke survivors for balance maintenance

Stroke survivors often experience balance impairments which may result in increased risk of falling. However, it is unclear whether and how a stroke changes cortical involvement for postural control. To clarify this issue, we assessed the effect of stroke on sway-based corticokinematic coherence (CKC), which is a measure of the coupling between cortical electrophysiological signals and postural sways. To that end, we recorded the center-of-pressure fluctuations and electroencephalographic cortical activity of 34 stroke survivors and 34 healthy participants performing balance tasks during which sensory information was manipulated, by either removal or alteration. We found significantly increased CKC derived from medio-lateral sway in stroke participants when standing on foam compared to healthy controls, suggesting an increase in cortical involvement to compensate for the decreased function of the hemiparetic side, even in highly functional stroke survivors. Moreover, a relationship was found between CKC and clinical scores (Berg Balance Scale and Fugl-Meyer). This suggests that CKC could be used as a biomarker to track progress beyond traditional functional recovery as measured by clinical scores.

neuroscience↗

bioRxiv2025

Proprioceptive and visual motion detection acuity contribute to children dynamic postural control

Acquiring efficient postural control strategies is key to childrens proper motor development. For that, the brain needs to continuously integrate sensory information and convert it into corrective motor commands. Although this entire process naturally hinges on the reliability of early senses, very few studies have investigated early sensory acuity and its role in postural stability during development. Clarifying this could lead to a better understanding of conditions, such as developmental coordination disorder (DCD), where the impairment of balance control is substantial. Here, we tested 25 typically developed school-aged children with a Visual Motion Detection test (VMDT), an ankle Joint Position Sense test (aJPST), force-plate assessed posturography, and the Movement Assessment Battery for Children - Second edition (MABC-2). We found a significant correlation between the balance score of the MABC-2 and both VMDT score (r = 0.60, p = 0.003) and aJPST score (r = -0.47, p = 0.02). However, no such relationship was found between the force-plate assessed sway amplitude during upright standing and the two sensory acuity scores. Importantly, the MABC-2 balance scores were associated with upright stability, but only to a limited extent. Given that the MABC-2 balance component factors in static and dynamic balance while posturography focuses only on static balance, our results point at a key role of early sensory acuity for dynamic balance. Together, these findings bring attention to possible clinical tools for motor impairment detection and subsequent rehabilitation strategies during development.

neuroscience↗

bioRxiv2024

Transcallosal generation of phase aligned beta-bursts underlies TMS-induced interhemispheric inhibition

The excitability of the sensorimotor (SM1) cortices is reflected in the bilateral [~]20 Hz beta oscillations. The extent to which these oscillations subtend the interhemispheric inhibition (IHI) captured by the Transcranial Magnetic Stimulation (TMS) ipsilateral Silent Period (iSP) protocol remains unclear. Therefore, we investigated the relationship between movement-related beta suppression and the iSP, along with their role for manual dexterity. Forty adults underwent an Electroencephalography assessment of beta suppression during volitional left hand movement and a TMS assessment of iSP recorded from the right hand. In both cases, left SM1 beta oscillations (contralateral to the activated right SM1), were monitored through a proxy signal - the Electromyography of the contracted right hand. Bimanual dexterity was assessed with the Purdue Pegboard. Volitional movement caused significant bilateral SM1 beta suppression in nearly all participants ([≥] 85 %). ISPs were observed in every participant. In the proxy signal for the left SM1, the iSP coincided with TMS-evoked high-amplitude beta bursts. These bursts showed significant phase alignment across participants 10-70 ms after the TMS pulse. There was no significant association between the left-/right-hemisphere beta suppression, iSP, and bimanual dexterity. Our results highlight the distinct nature of beta oscillation changes during volitional movement compared to TMS-iSP and show that TMS induces IHI via transcallosal generation of phase aligned beta bursts. Furthermore, our data suggests that only the initial phase of a beta burst carries an inhibitory effect. It also highlights the possibility of evoking a beta burst with the iSP protocol, opening perspectives for future neuroimaging and modeling studies.

neuroscience↗