A biological walker is faster and better recognized when aligned with body axis observer.

The representation of the vertical direction is a compromise between the directions given by the egocentric and allocentric references. Dissociations between these two referentials in the discrimination of a biological walker which typically refers to a model of verticality questions the coordinate system (allocentric and/or egocentric) used to perceive it. With a point-light display paradigm, the characteristics of an artificial walking pattern were manipulated in order to offer to 10 healthy participants (5 men/5 women; 24.

Does proprioception contribute to the sense of verticality?

The representation of the vertical can be assessed by measuring the visual, tactile or perception of the postural vertical (PV). It is well accepted that visceral graviceptors and Golgi tendon receptors contribute to perception of the PV, whereas the role of muscular proprioception (Ia muscle spindles) remains to be clarified. The objective of this study was to analyze whether or not muscular proprioception contributes to the representation of verticality.

Effects of plantar flexor muscle fatigue induced by electromyostimulation on postural coordination.

The aim of the present study was to investigate the influence of a modification of an intrinsic capacity (plantar flexor strength) on the implementation of in-phase and anti-phase mode of coordination. Analysis of hip and ankle relative phases during fore-aft tracking task was done before and after an electromyostimulation fatigue protocol on the soleus muscles. Results showed participants used exclusively in-phase and anti-phase modes of coordination, with a sudden switch from one to the other with target frequency increase.

Optimization model predictions for postural coordination modes.

This paper examines the ability of the dynamic optimization model to predict changes between in-phase and anti-phase postural modes of coordination and to evaluate influence of two particular environmental and intentional constraints on postural strategy. The task studied was based on an experimental paradigm that consisted in tracking a target motion with the head. An original optimal procedure was developed for cyclic problems to calculate hip and ankle angular trajectories during postural sway with a minimum torque change criterion.