Reweighting of sensory inputs to control quiet standing in children from 7 to 11 and in adults.

How sensory organization for postural control matures in children is not clear at this time. The present study examined, in children aged 7 to 11 and in adults, the postural control modifications in quiet standing when somatosensory inputs from the ankle were disturbed. Since the reweighting of sensory inputs is not mature before 10, we hypothesized that postural stability was more affected in children than in adults when somatosensory inputs were altered and that this postural instability decreased as age increased during childhood.

Short-term memory effects of an auditory biofeedback on isometric force control: is there a differential effect as a function of transition trials?

The aim of the present study was to investigate memory effects, force accuracy, and variability during constant isometric force at different force levels, using auditory biofeedback. Two types of transition trials were used: a biofeedback-no biofeedback transition trial and a no biofeedback-biofeedback transition trial. The auditory biofeedback produced a low- or high-pitched sound when participants produced an isometric force lower or higher than required, respectively.

Local and global effects of neck muscle vibration during stabilization of upright standing.

Neck muscle vibration (NMV) during upright standing is known to induce forward leaning, which has been explained as a global response to the (illusory) perception of a lengthening of the dorsal neck muscles. However, the effects of NMV both at the level of individual joints and on whole-body postural coordination, and its potential modulation by vision, have not yet been analyzed in detail. Eight healthy young adult participants completed a total of ten trials each, with a 10-s period of unperturbed standing followed by a 10-s period of NMV.

Age-related differences in cognitive and postural dual-task performance.

The present experiment assessed, in children aged 7-11 and in adults, whether postural control is affected by cognitive processes and vice versa. Using a dual-task, the level of difficulty of a Stroop task and bipedal quiet stance varied alternatively. We hypothesised that the interference between cognitive and postural tasks was non-linear during childhood with a so-called turning point around 8.

Effects of mirror feedback on upright stance control in elderly transfemoral amputees.

Objective: To investigate the effects of mirror feedback on upright stance control in elderly transfemoral amputees.

Design: Before and after intervention trials.

Setting: University medical bioengineering laboratory.

Sensory supplementation through tongue electrotactile stimulation to preserve head stabilization in space in the absence of vision.

Purpose: To investigate the effectiveness of a head position-based, tongue-placed biofeedback system in providing sensory supplementation to preserve head stability in space in the absence of visual information.

Methods: Nine healthy young men with normal vision and no history of previous motor problems, neck injury, vertigo, neurologic disease, or vestibular impairment voluntarily participated in the experiment. They were asked to stand, their feet placed in a semitandem position, as immobile as possible in two conditions of No Vision and Vision and two conditions of No Biofeedback and Biofeedback.

Head position-based electrotactile tongue biofeedback affects postural responses to Achilles tendon vibration in humans.

The purpose of the present experiment was to investigate whether postural responses to ankle proprioceptive perturbation Achilles tendon vibration were affected by the availability of augmented sensory information about head orientation/motion with respect to gravitational vertical, i.e., normally provided by the vestibular system.

Dual-task study of cognitive and postural interference in 7-year-olds and adults.

The study examined, in children aged 7 and adults, the postural control when a cognitive task (modified Stroop) of varying level of difficulty is executed simultaneously. Postural difficulty also varied (with or without vibrations of the ankle joint). We hypothesized that children's performance was more affected than adults', when the difficulty of the cognitive and postural tasks increased.

The increased foreperiod duration to attain the neutral optimal preparation from sitting to standing.

The purpose of the present experiment was to investigate the effects of a neutral preparation during the foreperiod on motor and postural programming processes in a voluntary upper limb movement. The foreperiod duration (300, 500, 700 and 900 ms) and the postural condition (sitting vs standing) were manipulated using a neutral preparation (no advanced information during the preparatory signal). Thirteen subjects performed a raising arm movement with 1 kg load at the wrist.

Effects of foreperiod duration on anticipatory postural adjustments: determination of an optimal preparation in standing and sitting for a raising arm movement.

The purpose of the present experiment was to examine the motor and postural preparation processes evolving during the foreperiod (known to be optimal at 500 ms in sitting) in a voluntary upper limb movement executed while standing. The foreperiod duration (300, 500, 700 and 900 ms) and the postural conditions (sitting versus standing) were manipulated using a priming procedure. Two types of prime were provided: (1) a prime giving valid information on the side of the raising arm movement to execute, and (2) a prime giving non-valid information (prime opposite to the required side).

Predictable postural perturbation in premotor and motor components of reaction time.

The aim of the present experiment was to study the central control of posture and movement coordination. Subjects' task was voluntarily to raise their arms in response to a visual signal, this movement generating an unloading in which the weight of the load (0 gm, 1500 gm, 3000 gm, or 4500 gm) was known in advance. Thus, subjects could predict the postural perturbation generated by the unloading.