title: Postural sway and gaze can track the complex motion of a visual target.
abstract: Variability is an inherent and important feature of human movement. This variability has form exhibiting a chaotic structure. Visual feedback training using regular predictive visual target motions does not take into account this essential characteristic of the human movement, and may result in task specific learning and loss of visuo-motor adaptability. In this study, we asked how well healthy young adults can track visual target cues of varying degree of complexity during whole-body swaying in the Anterior-Posterior (AP) and Medio-Lateral (ML) direction. Participants were asked to track three visual target motions: a complex (Lorenz attractor), a noise (brown) and a periodic (sine) moving target while receiving online visual feedback about their performance. Postural sway, gaze and target motion were synchronously recorded and the degree of force-target and gaze-target coupling was quantified using spectral coherence and Cross-Approximate entropy. Analysis revealed that both force-target and gaze-target coupling was sensitive to the complexity of the visual stimuli motions. Postural sway showed a higher degree of coherence with the Lorenz attractor than the brown noise or sinusoidal stimulus motion. Similarly, gaze was more synchronous with the Lorenz attractor than the brown noise and sinusoidal stimulus motion. These results were similar regardless of whether tracking was performed in the AP or ML direction. Based on the theoretical model of optimal movement variability tracking of a complex signal may provide a better stimulus to improve visuo-motor adaptation and learning in postural control.
authors.affiliation: Motor Control and Learning Laboratory, School of Physical Education and Sport Science, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Vassilia
authors.initials: V
authors.lastname: Hatzitaki
authors.affiliation: Biomechanics Research Building, University of Nebraska at Omaha, Omaha, Nebraska, United States of America.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Stergiou
authors.affiliation: Motor Control and Learning Laboratory, School of Physical Education and Sport Science, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Sofianidis
authors.affiliation: Biomechanics Research Building, University of Nebraska at Omaha, Omaha, Nebraska, United States of America.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Kyvelidou
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D011187:Posture / Q000502:physiology*