Biology subjects

Dierick, F.

Publications and source records attributed to Dierick, F..

7 recordsLinked to original sources

bioRxiv2026

Grip Force Complexity Under Constraint: Evidence from Fractal and Entropy Analyses

The present study investigates how grip force (GF) and load force (LF) dynamics reorganize under varying task constraints, focusing on the fractal and entropic properties of motor output. Twenty healthy adults performed precision grip tasks across five force conditions: two spontaneous conditions (pre, post) without visual feedback and three target-driven conditions (natural, -10%, +10% of natural). The temporal and informational structure of GF and LF signals were quantified using the Hurst exponent (H) and Sample Entropy (SampEn), capturing long-range temporal organization and local irregularity. Constrained conditions reduced GF coefficient of variation but increased both H and SampEn relative to spontaneous pre-trials, while LF indices remained largely unchanged. Thus, grip control under constraint became more temporally persistent and locally irregular, suggesting a more structured temporal organization rather than a simple loss of complexity. Intra-trial analyses further revealed an increase in H from the first to the second half of spontaneous trials, consistent with progressive self-organization in the absence of explicit constraints. Across conditions, H and SampEn were positively correlated for both GF and LF, suggesting that predictability and complexity are not necessarily inversely related in this context. Overall, these findings suggest that the human motor system adapts to force constraints not by suppressing variability, but by reorganizing it across scales, combining temporal persistence with local flexibility. This multidimensional characterization of variability may help refine theoretical models of optimal movement variability and may inform clinical or training approaches aimed at assessing or enhancing neuromotor adaptability.

neuroscience↗

bioRxiv2023

Unveiling the Impact of Arsenic Toxicity on Immune Cells in Atherosclerotic Plaques: Insights from Single-Cell Multi-Omics Profiling.

Millions worldwide are exposed to elevated levels of arsenic. This significantly increases their risk of developing atherosclerosis, a pathology primarily driven by immune cells. While the impact of arsenic on immune cell populations in atherosclerotic plaques has been broadly characterized, cellular heterogeneity is a substantial barrier to in-depth examinations of the cellular dynamics for varying immune cell populations. Here, we present one of the first single-cell multi-omics profiling of atherosclerotic plaques in apolipoprotein E knockout (apoE-/-) mice to understand the transcriptomic and epigenetic changes in various immune cells induced by arsenic. Our data reveal that arsenic alters the transcriptional profile of macrophages in a subtype-specific manner with implicated shifts in cell-cell interaction and cell fate predictions. Additionally, our data suggest that arsenic-mediated changes in chromosome accessibility are more profound than their effects on the transcriptome, hence revealing markers of arsenic exposure and potential targets of interventions. TeaserArsenic changes gene expression and epigenome primarily of macrophages in atherosclerotic plaque, suggesting intervention targets.

pharmacology and toxicology↗

bioRxiv2019

Digital Natives and Dual Task: Handling It But Not Immune Against Cognitive-Locomotor Interferences

Digital natives developed in an electronic dual tasking world. This paper addresses two questions. Do digital natives respond differently under a cognitive load realized during a locomotor task in a dual-tasking paradigm and how does this address the concept of safety? We investigate the interplay between cognitive (talking and solving Ravens matrices) and locomotor (walking on a treadmill) tasks in a sample of 17 graduate level participants. The costs of dual-tasking on gait were assessed by studying changes in stride interval time and its variability at long-range. A safety index was designed and computed from total relative change between the variability indices in the single walking and dual-task conditions. As expected, results indicate high Ravens scores with gait changes found between the dual task conditions compared to the single walking task. Greater changes are observed in the talking condition compared to solving Ravens matrices, resulting in high safety index values observed in 5 participants. We conclude that, although digital natives are efficient in performing the dual tasks when they are not emotional-based, modification of gait are observable. Due to the variation within participants and the observation of high safety index values in several of them, individuals that responded poorly to low cognitive loads should be encouraged to not perform dual task when executing a primate task of safety to themselves or others.

physiology↗

bioRxiv2019

Adiabatic invariants drive rhythmic human motion in variable gravity

Natural human movements are stereotyped. They minimise cost functions that include energy, a natural candidate from mechanical and physiological points of view. In time-changing environments, however, motor strategies are modified since energy is no longer conserved. Adiabatic invariants are relevant observables in such cases, although they have not been investigated in human motor control so far. We fill this gap and show that the theory of adiabatic invariants explains how humans move when gravity varies.

biophysics↗

bioRxiv2019

Age-related kinematic behavior on fast head-neck rotation target task in non-painful individuals aged from 8 to 85 years old

RationaleKinematic behavior during fast cervical rotations is a useful parameter for assessing sensorimotor control performances in neck-pain patients. However, in asymptomatic individuals from children to seniors, the influence of age still needs to be explored. Aim and methodWe assessed the impact of age on sensorimotor control performance of the head-neck with execution time and kinematic variables (time of task, mean speed/acceleration/deceleration, overshoots, minimum/maximum speed) during standardized fast rotation target task using the DidRen Laser test. Eighty volunteers were stratified in four different age-groups: Children [8-14y]: n=16; Young Adults [18-35y]: n=29; Old Adults [36-64y]: n=18; Seniors [65-85y]: n=17. ResultsTo perform the test, Children were slower compared to Young Adults (p<0.001) and Old Adults (p<0.001). It was also slower in Seniors compared to Young Adults (p<0.013). Mean speed was slower in Children and Seniors compared to Young Adults (p<0.001) and Old Adults (p<0.001). Mean acceleration was slower for Children compared to Young Adults (p<0.016) and Old Adults (p<0.015). Mean deceleration was slower for Children compared to Young Adults (p<0.001) and Old Adults (p<0.003). ConclusionThe DidRen Laser test allows us to discriminate age-specific performances for mean speed, acceleration and deceleration. Seniors and Children needed to be slower to become as precise as Young and Old people, no difference was observed for overshoots which assesses accuracy of movement. Age must therefore be considered as a key parameter when analyzing execution time and kinematic results during DidRen Laser test.

physiology↗

bioRxiv2018

Clinical and MRI changes of puborectalis and iliococcygeus after a short period of intensive pelvic floor muscles training with or without instrumentation. A randomized study

PurposeThis study evaluates the impact of a 3-week period of intensive pelvic floor muscles training (PFMT), with or without instrumentation, on clinical and static magnetic resonance imaging (MRI) changes of puborectalis (PR) and iliococcygeus (IL) muscles.\n\nMethods24 healthy young 5 women were enrolled in the study and 17 achieved the 9 sessions of 30 minutes training exercises and conducted all assessments. Participants were randomly assigned in two training groups: voluntary contractions combined with hypopressive exercises (HYPO) or biofeedback exercises combined with transvaginal electrical stimulations (ELEC). Clinical and T2-weighted MRI assessments io were realized before and after training.\n\nResultsModified Oxford Grading System (MOGS) scores for left PR and perineal body significantly increased in the two groups (p=0.039, p=0.008), but MOGS score for right PR significantly increased only in HYPO (p=0.020). Muscle volumes of right and left IL significantly decreased (p=0.040, p=0.045) after training as well as signal i5 intensities of right and left PR (p=0.040, p=0.021) and thickness of right and left IL at mid-vagina location (p=0.012, p=0.011).\n\nConclusionsA short period of intensive PFMT induces clinical and morphological changes in PFMs at rest suggesting a decrease in IL volume and adipose content of PR. Given the difference in cost and accessibility between HYPO and ELEC approaches, PFMT should be based primarily on non-instrumented exercises.

physiology↗

bioRxiv2017

Apparent diffusion in nucleus pulposus is associated with pain and mobility improvements after spinal mobilization for acute low back pain

Pain perception, trunk mobility in flexion, extension, and lateral flexion, and apparent diffusion coefficient (ADC) within nucleus pulposus of all lumbar discs were collected before and after posterior-to-anterior mobilization in 16 adults with acute low back pain. ADC was computed from diffusion maps and 3 specific portions of the nucleus pulposus were investigated: anterior (ADCant), middle (ADCmid), and posterior (ADCpost), and their mean as ADCall, a summary measure of ADC within nucleus pulposus. Pain ratings were significantly reduced after mobilization, and mobility of the trunk was significantly increased. Concomitantly, a significant increase in ADCall values was observed. The greatest ADCall changes were observed at the L3-L4 and L4-L5 levels and were mainly explained by changes in ADCant and ADCpost. The simultaneous reduction in pain and increase of water diffusion within nucleus pulposus has has been previously observed in subjects with chronic conditions and exists in the acute phase of the disease. Since the largest changes in ADC were observed at the periphery of the nucleus pulposus, and taken together with pain decrease, our results suggest that increased peripheral random motion of water molecules is implicated in the modulation of the intervertebral disc nociceptive response.

physiology↗