Neck Muscle Vibration Modifies the Representation of Visual Motion and Direction in Man

Abstract

The retinal coordinates of an image are normally insufficient to define the direction of an object in body-centred visual space. Gaze direction, specified by information on the position of eye-in-head and on the position of head-on-torso, is also required. While the source of the eye-in-head signal is controversial, it is clear that proprioceptive signals from neck muscles are sufficient to provide head-on-torso information. Observations by Goodwin et al., beginning in 1972, that vibration of limb muscles modifies proprioception from them, and induces illusory motion and false perception of limb position, suggested this study of the effects of neck muscle vibration on the representation of visual space. Verbal reports, supported by objective measures, revealed that vibration of muscles on one side of the neck induces a visual illusion: contralateral displacement of a small visual target viewed in the dark. Pointing movements towards the target are similarly affected, confirming that the representation of directions in visual space is modified by neck muscle vibration. A second vibration-induced illusion was uncovered when apparent displacement ceased. This is an illusion of pure target motion in the same direction as the previously observed displacement. The magnitudes of both the displacement and pure motion illusions were dependent on vibration amplitude and were unrelated to real or apparent movements of eyes or head. Taken together these observations indicate that vibration of neck muscles can modify independently (1) the central representation of the instantaneous direction of gaze and (2) the signal of the velocity with which this direction is changing.

Location memory biases reveal the challenges of coordinating visual and kinesthetic reference frames

“…Results showed some suggestion that subjects were using body midline as a reference frame in a manner similar to the visible reference, although without the stability for targets aligned with body midline. This lack of stability in perception of body midline in dark conditions may be related to contributions from both visual and kinesthetic inputs in the Vis conditions of Experiments 1 and 2 (e.g., Biguer et al 1988;Karnath et al 2002). For instance, the locations of visual targets viewed in a dark environment may influence perceived body midline, with potentially enhanced perception of body midline with a broader range of target locations.…”

Muscular proprioception contributes to the control of interceptive actions.

“…Following the work of Biguer et al (1988), we hypothesized that continuous tendon vibration would lead participants to misperceive the position of the head relative to the trunk and, as a consequence, make judgment errors. Indeed, Right vibration should cause participants to make early judgments (in comparison with the control condition), while Left vibration should cause participants to make late judgments.…”

“…vibration should elicit late judgments due to an illusory sensation of trunk displacement toward the left (cf., Biguer et al, 1988).…”

“…Indeed, when vibrating the inferior rectus muscle of the participant's eye and/or the sterno-cleidomastoidus muscle, the participant perceives a slow target illusory movement in the upward direction (Roll et al, 1991). In the same way, vibrating left posterior neck muscles gives rise to a kinesthetic illusion of a slow target movement to the right (Biguer et al, 1988;Taylor & McCloskey, 1991). More interestingly, manipulating the muscular proprioceptive channel also affected pointing movements, since vibrating neck muscles gives rise to a pointing bias in the direction of the perceived movement of the target (Roll et al, 1991).…”

“…This methodology has never been used to identify the role of proprioception in interceptive tasks. Biguer et al (1988) asked participants to stop a moving spot when they thought it would cross their body midline. This experiment was designed to provide an objective measurement of the illusory sensation of displacement using a perceptual task.…”