A Complex Semi-automatic Method for Kinetic and Two-dimensional Kinematic Motion Analysis for Posture and Movement Investigation

Functional reach (FR) – maximal forward reach with both arms while standing, is a well-known dynamic balance test. Different underexplained reaching strategies exist. This study was motivated by the need of an affordable and robust approach for their evaluation. We introduce a complex semi-automatic method for two-dimensional kinematic and kinetic analysis based on video capture with inexpensive camera, free automatic marker tracking software, pedobarographic measurements and problem-oriented algorithms for kinetic and kinematic data evaluation. Subjects performed FR with passive markers on their right side while standing on a Tekscan platform. Kinematic and kinetic data were simultaneously collected. Video trimming by sound was applied for synchronization between video and platform recordings. Automatic object tracking by color (Viana.Net) was applied for kinematic measurements. Center-of-pressure excursions were evaluated by Tekscan software. All data were further processed by problem-oriented algorithms (MatLab). Evaluated measures: FR length, horizontal and vertical marker paths, ankle and hip angles and their corresponding linear or angular velocities while moving forward or backward. During these movements the horizontal displacements of the center-of-gravity marker highly correlated with center-of-pressure anterior-posterior sway. The method allows measuring distances, angles and velocities. It is prospective for concerted kinetic and two-dimensional kinematic analysis of dynamic standing balance

Posture, Balance and the Brain International Workshop Proceedings Posture, Balance and the Brain Creative Commons BY-NC-SA 4.0 Sensory Conflict Influence on Functional Reach Performance and Dynamic Standing Balance

ABSTRACT: Adequate integration of sensory information from different modalities is essential for standing balance. Inadequate and/or incongruent information inputs cause sensory conflict which endangers equilibrium. That is even more expressed during dynamic suprapostural tasks, such as functional reach (FR). Our aim was to study the influence of sensory conflict on FR performance and dynamic standing balance steadiness. Ten healthy right-handed adults performed FR standing on a pedobarographic platform in four sensory conditions: eyes-open (EO), eyes-closed (EC), head in maximal extension and eyes open or closed (EO-HE/EC-HE), adding conflict of vestibular origin. Data were analyzed by Two-Way RM Anova and paired t-test. Factor vision was significant, while only a tendency for head position was found for FR, which shortens in EC, EO-HE and especially EC-HE. For center of pressure (COP) sway path both vision and head position were significant factors. Sway path increased in both EC conditions compared to EO, respectively. Head extension also increased sway path, differences were found between EC and EC-HE. The longest sway path was in EC-HE. Only vision was significant for medio-lateral (M-L) COP sway, which increased in EC compared to EO, respectively. Again, the greatest sway was in EC-HE. The increased COP sway path and M-L sway correspond with decreased FR performance. All these results suggest that absence of vision and/or inadequate vestibular information input, deteriorate dynamic standing balance and task performance, which is expressed the most when both sensory modalities are affected. Factor head position was significant for forward and backward COP velocities (when subjects reach forward and return to initial position). For forward velocity there was significant diminution only between EC-HE and EO, for backward velocity -between EO and both HE conditions. These results suggest that altered vestibular information probably causes velocity decrease. Accuracy of return from FR to initial COP position was greater in EC than in EO. This may be explained by increased weight of proprioception in absence of visual information and/or increased confidence in its presence. Our study suggests a correlation between balance steadiness and suprapostural task performance during sensory conflict. Absence of vision has more impact than altered vestibular information in all cases but for the decrease in FR task dynamics

Posture, Balance and the Brain International Workshop Proceedings Posture, Balance and the Brain Creative Commons BY-NC-SA 4.0 Audio-Visual Entrainment Influence on Postural Dynamics

ABSTRACT: The influence of multimedia on modern digital users is constantly growing. The paper describes an experimental study of audio-visual (AV) entrainment towards dynamical changes of selected human biometrics. Special wearable equipment of AV stimulation and polyphysiographic postural and brain activities recordings were accomplished for entrainment effect exploration. The obtained results demonstrated evident quantitative changes in both center-ofpressure sway and EEG of the studied subjects after the entrainment session, outlined with time-frequency spectral and multifractal measures. Practical implementation of the study results is directly applicable to the rehabilitation goals and nowadays digital world people stress relaxation, together with working capacity enlargement by multimedia applications

Interactions between Cortical Rhythms and Spiking Activity of Single Basal Ganglia Neurons in the Normal and Parkinsonian State

In order to evaluate the specific interactions between cortical oscillations and basal ganglia–spiking activity under normal and parkinsonian conditions, we examined the relationship between frontal cortex electroencephalographic (EEG) signals and simultaneously recorded neuronal activity in the internal and external segments of the pallidum or the subthalamic nucleus (STN) in 3 rhesus monkeys. After we made recordings in the normal state, hemiparkinsonism was induced with intracarotid injections of the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in one animal, followed by additional recordings. Spiking activity in the pallidum and STN was associated with significant shifts in the level of EEG synchronization. We also found that the spectral power of beta- and gamma-band EEG rhythms covaried positively before the basal ganglia spikes but did not covary or covaried negatively thereafter. In parkinsonism, changes in cortical synchronization and phase coherence were reduced in EEG segments aligned to STN spikes, whereas both were increased in data segments aligned to pallidal spikes. Spiking-related changes in beta/gamma-band covariance were reduced. The findings indicate that basal ganglia and cortex interact in the processing of cortical rhythms that contain oscillations across a broad range of frequencies and that this interaction is severely disrupted in parkinsonism