Postural responses to vibrostimulation of the neck muscle proprioceptors in man

Effect of gaze on postural responses to neck proprioceptive and vestibular stimulation in humans

“…However, because the vestibular input is constant, the head might be interpreted as stationary and the trunk tilted backwards with respect to the support surface, therefore the postural reaction occurs in the forward direction. It is considered unlikely that body sway results from a simple cervico-spinal response (Magnus, 1924) since: (i) the subjects showed the same body sway direction when head and trunk were turned together ( Figs 2B and 3), and (ii) it was shown that the direction of body sway is coherent with illusory or hypnotically suggested head orientations rather than with the actual head orientations (Gurfinkel et al 1989(Gurfinkel et al , 1992Smetanin et al 1993). (b) Galvanic stimulation of the vestibular system is normally interpreted as a lateral tilt of the body relative to gravity as sensed by the labyrinthine organs (Popov et al 1986;Fitzpatrick et al 1994;Hlavacka et al 1995;Day et al 1997).…”

“…1B). In fact, if vibration is applied asymmetrically it may induce lateral displacements even when the head and eyes are in the primary (straight ahead) direction (Smetanin et al 1993). In two subjects we tested different frequencies (in the range 40-100 Hz) and amplitudes (0·5 and 0·8 mm) of neck muscle vibration in order to verify whether the direction of the postural response could depend on the stimulus parameters.…”

“…When applied to a standing human subject with the head, trunk and eyes in a primary position (straight ahead), neck muscle vibration causes forward body lean (Gregoric et al 1978). Rotation of the head to the shoulder redirects the sway so that it becomes more lateral: stimulation of either the left or the right side of the neck, with the head turned to the left, induces a left lateral component of body sway, and with the head turned to the right induces right lateral sway (Smetanin et al 1993). The direction of this response and its dependence on head orientation, the increase in the response on unstable supports (Ivanenko et al 1999), the asymmetry in the response shown in unilateral labyrinthine-defective patients (Popov et al 1996) and the absence of the response in bilateral labyrinthine-defective patients (Lekhel et al 1997) led to the hypothesis that the sway is an involuntary response due to a central interpretation of neck afferent and vestibular signals of head motion.…”

Neck Muscle Vibration and Spatial Orientation During Stepping in Place in Humans

“…In "neglect" patients, neck muscle vibration can compensate the horizontal displacement of the sagittal midplane (Karnath 1994;Karnath et al 1993). In standing subjects, neck muscle vibration induces body tilt and increased sway, suggesting that posture is organized with respect to a "body schema," to the construction of which neck input contributes together with eye and skeletal muscle (Eklund 1972;Gurfinkel et al 1995;Ivanenko et al 1999;Kavounoudias et al 1999;Roll et al 1989b;Smetanin et al 1993). Most likely, the parietal cortex contributes to the egocentric representation of space, since many of its areas receive signals from neck muscles and from the labyrinth (Bottini et al 2001).…”

Postural Stability and Visual Verticality Perception of Neck Disturbance of the Middle-aged during Quiet Standing

“…It provides information on the position of the head and body [1][2][3][4][5] as well as motions and localizations of visual objects [2][3][4][5][6] . The neck functions in body balance maintenance through activity of the high density of deep neck muscle spindles 7) .…”