Biology subjects

den Otter, R.

Publications and source records attributed to den Otter, R..

3 recordsLinked to original sources

bioRxiv2025

Trial-Level Sequence Modeling Reveals Hidden Dynamics of Dual-Task Interference

Theories of dual-task interference assume that the same cognitive operations underlie multitasking regardless of stimulus timing, yet this core assumption has remained untested due to methodological limitations of behavioral averaging. Here, we combine hidden multivariate pattern (HMP) analysis with deep spatiotemporal sequence modeling of single-trial EEG to uncover the neural dynamics of multitasking in the psychological refractory period (PRP) paradigm. Using a deep spatiotemporal sequence model trained on Long stimulus-onset asynchrony (SOA) trials, we identify Encoding, Central, and Response operations and show that these same operations occur in the Short SOA condition, demonstrating shared cognitive processes across interference conditions. Additionally, trial-level decoding reveals multiple distinct sequences of cognitive operations across both tasks during interference, varying both within and across individuals. These sequences predict behavioral differences in reaction time and accuracy, revealing how interference timing within the cognitive operation sequence influences performance. In other words, we found trial-by-trial variability related to individual strategies directly affecting accuracy and reaction time (RT). Our findings challenge static bottleneck accounts and establish trial-level sequence modeling as a powerful tool to investigate the hidden dynamics of multitasking.

neuroscience↗

bioRxiv2025

The Effect of Physical Activity Level on Age-Related Differences in Responses to Optic Flow Perturbation during Human Walking

BackgroundHuman aging increases the reliance on vision for walking balance due to age-related declines in proprioceptive and vestibular function. Regular physical activity (PA) may reduce the reliance on visual input during walking. This study examined whether PA levels modulate age-related responses to perturbations of the optic flow that is crucial in the control of human locomotion. MethodsSixty active and inactive younger (YA and YI: 23.3{+/-}3.91 y) and older adults (OA and OI: 68.3{+/-}3.98 y; n=15 for each group) walked on a treadmill in front of a virtual hallway. The walking protocol consisted of 3-minute walking without, and 8-minute with mediolateral optic flow perturbation. Sacrum and heel marker positions and ground reaction forces were recorded. Power spectral density (PSD) of the mediolateral sacrum position and gait parameters were analyzed. ResultsThe PSD increased more in OA compared to OI adults (p=0.041) while YA and YI adults did not differ. Mean (and variability of) step width and mediolateral margin of stability increased irrespective of age and PA (all p<0.001). During the 8-minute perturbation, OA adults demonstrated greater decreases in PSD than the OI adults (p=0.039). Additionally, the variability in the mediolateral margin of stability reduced more in YA and OA adults compared to YI and OI adults (p=0.048). ConclusionHigher PA levels in OA adults were associated with stronger immediate responses in body sway to optic flow perturbations compared to older inactive and younger adults. This may support the beneficial effects of physical activity on age-related visual dependency during gait.

neuroscience↗

bioRxiv2025

The effects of gait speed on the responses to immediate and prolonged exposure to mediolateral optic flow perturbation in healthy young adults

BackgroundOptic flow is vital for locomotor control and is often perturbed to study the impact of optic flow on balance control. However, it remains unclear whether gait speed influences responses to such perturbations. This study aims to examine the effects of gait speed on gait parameters following immediate and prolonged exposure to mediolateral optic flow perturbations. MethodsTwenty-one young adults (23.43 {+/-} 4.19 years) walked on an instrumented treadmill, including 3 phases: baseline (3 min), perturbation with mediolateral optic flow (8 min), and post-perturbation (3 min). Trials were conducted at 0.6, 1.2, and 1.8 m/s. Ground reaction forces and 3D motion data were collected to calculate mediolateral margin of stability (MoS), mean step length (SL), step width (SW) and their variabilities. Three repeated-measures ANOVAs (Speed by Phase) were used to compare: baseline vs. early perturbation, early vs. late perturbation, and baseline vs. post-perturbation. ResultsThe responses to immediate and prolonged exposure to optic flow perturbation were speed dependent. Walking at slow speeds induced greater immediate responses in mediolateral gait parameters (SW and mediolateral MoS, both p < 0.001) compared to walking at faster speeds. During the perturbation phase, the adaptations were larger at faster vs. slower speeds for gait parameters in the direction of movement (SL, p = 0.007). ConclusionImmediate responses and adaptations to mediolateral optic flow perturbations are speed-dependent and larger at slower gait speeds. The responses to prolonged perturbation are interpreted as step-to-step adaptations that may inform future interventions and studies on gait speed selection.

neuroscience↗