About the Postural Control Laboratory

    Evaluation of dynamic postural control for experimental studies and medical testing of astronauts is supported using modified and enhanced versions of the commercially available EquiTest computerized dynamic posturography system developed by NeuroCom, International (Clackamas, OR, USA) for clinical assessment of disorders in balance control.

    Posture Platform used to test balance control Posture Platform used to test balance control
    The standard EquiTest system consists of a computer-controlled, motor-driven support surface and visual surround. Force transducers beneath the support surface can be used to servo-control the pitch of the support surface and/or visual surround Posture Platform used to test balance controlto follow the sway of a subject, thus decoupling proprioceptive and/or visual sensory feedback respectively from the true orientation of the subject. The support surface can also be driven to provide rapid (~0.4s) constant velocity perturbations to the postural control system by altering either the pitch or the fore-aft horizontal position of the platform.

    In order to improve the sensitivity of the posture platform system, and to improve our ability to interpret its output our EquiTest systems has been modified to monitor and record 3-dimensional multi-segment kinematics of sway using an OPTOTRAK 3020 active marker motion analysis system developed by Northern Digital, Inc. (Waterloo, Ontario, Canada). This system is currently equipped to track up to twelve infrared light emitting diodes at a maximum sampling frequency of 3500 Hz divided by the number of markers being used. Other EquiTest systems are equipped with a swaybar system to measure horizontal (anterior-posterior) positions of the hips and shoulders using rotational potentiometers. Both systems have Watson ARS-C241-A1 angular rate sensors (Eau Claire, WI, USA) to measure pitch and roll velocities of the head, and an EMG system capable of recording the activity of six muscle groups.