Journal of Vestibular Research - Volume 7, issue 2-3

Authors: DiZio, P. | Lackner, J.R. | Mergner, T.

Article Type: Editorial

DOI: 10.3233/VES-1997-72-301

Citation: Journal of Vestibular Research, vol. 7, no. 2-3, pp. 87-88, 1997

Authors: Pettorossi, V.E. | Errico, P. | Ferraresi, A.

Article Type: Research Article

Abstract: Quick phases (QPs) induced by horizontal and vertical sinusoidal vestibular stimulations were studied in rabbits, cats, and humans. In all the animals, large and frequent horizontal QPs were observed following yaw stimulation in prone position. By contrast, QPs were almost absent during roll stimulation in rabbits, and they were small and oblique during pitch stimulation in cats and humans. As a result of these differences, the range of gaze displacement induced by vestibular stimulations was greater in the horizontal plane than in the vertical one. We also found that the trajectory of the QPs in rabbits was kept horizontal even …when the yaw rotation was off vertical axis of ±45° in the sagittal plane. Moreover, in the rabbit, the rare horizontal QPs induced by roll stimulation did not change their orientation at various pitch angles of roll stimulation axis. The QPs were also analyzed following roll stimulation of the rabbit in supine position. In this condition, in which the otolithic receptors were activated in the opposite way compared to prone position, large vertical QPs were elicited. We concluded that these results provide evidence that the otolithic signal plays a role in controlling occurrence and trajectory orientation of the QPs. Show more

Keywords: vestibulo-ocular reflex, quick phases, otolithic receptors, gravity

DOI: 10.3233/VES-1997-72-302

Citation: Journal of Vestibular Research, vol. 7, no. 2-3, pp. 89-99, 1997

Authors: Lacour, Michel | Sun, Jiurong | Harlay, Françoise

Article Type: Research Article

Abstract: The vestibular syndrome following unilateral lesion of the vestibular system and the subsequent behavioral compensation over time have been well documented in many species. However, the locomotor pattern changes and the behavioral strategies used to preserve balance have still not been described. This study was aimed at quantitatively describing posturolocomotor behavior in cats tested before and after unilateral vestibular neurectomy (UVN) by the rotating beam test, which provides locomotor tasks of various difficulty. The position of head, neck, and trunk and the trajectory of the forelimbs and hindlimbs were recorded in 5 cats by 3D motion analysis. Step length and …frequency, walking velocity, and body height were computed. Results showed that normal cats adapted their locomotor patterns to the speed of beam rotation by increasing step length and/or frequency, that is, by increasing walking velocity, but without drastically changing their body posture. By contrast, UVN cats typically lowered their body centers of gravity and modified their locomotor patterns according to the locomotor task. Mean walking velocity was decreased in the low range of beam rotation as a result of smaller step length and lower frequency, and it was increased in the high range by opposite effects on these step cycle parameters. Modifications of the locomotor parameters were a function of the direction of beam rotation, showing significant reduction of step length, frequency, and velocity in the low range of counterclockwise compared to clockwise beam rotation, that is, during rotations toward the lesioned side. Phase plane plots of foot linear velocity with respect to foot linear displacement along the horizontal longitudinal axis displayed two different limit cycles, adapted to easy (low range of beam rotation) and more difficult (high range of rotation) walking conditions, in the normal cat. These dynamic profiles of the trajectories of the limbs during the step cycle were not greatly modified after vestibular lesion, but the phase plane typically observed in the high range for the normals was also found in the low range for the UVN cats. Thus, locomotor equilibrium function in the cat is strongly impaired following UVN, but locomotor balance can still be achieved in the UVN cats by the development of adaptive posturolocomotor strategies compensating for the lack of vestibular inputs. Show more

Keywords: locomotion, kinematics, unilateral vestibular neurectomy, cat

DOI: 10.3233/VES-1997-72-303

Citation: Journal of Vestibular Research, vol. 7, no. 2-3, pp. 101-118, 1997

Authors: Maurer, C. | Kimmig, H. | Trefzer, A. | Mergner, T.

Article Type: Research Article

Abstract: Object localization in space signals in the absence of an external reference (visual, auditory, haptic) involves a signal of the head in space (vestibular). The present study asks whether signals of body position relative to the support surface (proprioceptive) are involved as well, by investigating the role of vestibular-neck interaction (dissociating head and trunk position). Normal human subjects saw a light spot (object) and continuously nulled displacement steps of the spot. They did so before and after vestibular and/or neck rotational stimulation in the horizontal plane, reproducing a predesignated object localization in space (i), relative to the head mid-sagittal (ii), …and relative to the trunk mid-sagittal (iii). The predominant frequency contained in the stimuli was varied (0.05, 0.1, and 0.4 Hz). (I) Object localization in space upon whole-body rotation (vestibular stimulus) at high frequency was veridical, whereas that at low frequency fell short. Almost identical results were obtained for trunk rotation about the stationary head (neck stimulus). In contrast, when combining the stimuli in the form of head rotation on the stationary trunk, the results were veridical, independent of stimulus frequency. Additional findings obtained with a large variety of vestibular-neck stimulus combinations suggest a linear summation of vestibular and neck signals. (II) Object localization with respect to the head was approximately veridical, being independent of vestibular and neck stimulation. However, this only applied if subjects were not biased by a head-in-space motion illusion of neck origin. (III) Object localization with respect to the trunk was veridical in all conditions tested. The findings support a recently developed concept, according to which humans evaluate the kinematic state of a visual object in space by (a) relating it to that of the body support by means of an essentially ideal proprioceptive coordinate transformation, and (b) relating, in turn, the kinematic state of the support to a vestibularly derived notion of space, using a proprioceptive coordinate transformation that “knows” the vestibular transfer characteristics. One important aspect is that object localization in space always is veridical during head and trunk rotation relative to a stationary support (for example, the ground) despite non-ideal vestibular transfer characteristics. Additional findings in patients with chronic loss of vestibular function confirm this concept. Show more

Keywords: vestibular-neck interaction, visual object localization, self-motion perception, space coordinate system, trunk coordinate system, head coordinate system, human, vestibular loss patients

DOI: 10.3233/VES-1997-72-304

Citation: Journal of Vestibular Research, vol. 7, no. 2-3, pp. 119-135, 1997

Authors: Blouin, Jean | Gauthier, Gabriel M. | Vercher, Jean-Louis

Article Type: Research Article

Abstract: The vestibular signal plays a significant role in sensing changes in head orientation during rotations and in determining the magnitude of the rotations, but has only minor contributions in updating the internal representation of object positions with respect to the body after body rotations. The small contribution of the vestibular signal in egocentric object localization was evidenced in experiments in which the subjects reported the remembered position of eccentric earth-fixed targets after passive body rotations. The experiment reported here tested whether motor systems, such as the oculomotor system, make use of vestibular signals to generate accurate goal-directed motor responses toward …a target whose position needs to be updated with respect to the body during and after whole-body rotations. The results showed that although subjects can produce saccadic eye movements of about the same magnitude as passive whole-body rotations (as previously reported by a number of researchers), they failed to generate accurate saccades toward the position of an extinguished peripheral visual target after the rotation. Overall, these results combined with those found in the literature suggest different central processes for determining changes in body orientation in complete darkness and for updating a target position with respect to the body during and after body rotations. Show more

Keywords: vestibular signal, body orientation, space perception, object localization, human

DOI: 10.3233/VES-1997-72-305

Citation: Journal of Vestibular Research, vol. 7, no. 2-3, pp. 137-143, 1997

Authors: Assaiante, C. | McKinley, P.A. | Amblard, B.

Article Type: Research Article

Abstract: The main purpose of this study was to investigate the development of head-trunk coordination during single hops using one foot or two feet in children of two ages (5.5 to 6 and 7 to 7.5) and adults (n = 6/group). The kinematics of the subjects' hops were analyzed by means of an automatic optical TV-image processor called the ELITE system. The absolute angular dispersion of the head, trunk, and leg about the pitch and the roll axis were measured. Head and trunk pitch and roll anchoring indexes were calculated in order to compare the stabilization of a given segment with …respect both to external space and to the underlying anatomical segment. Results were analyzed separately for 3 phases: take-off, flight, and landing. Only the last two phases, flight and landing, are presented in this paper, and the following was found: 1) During flight, under both unipedal and bipedal conditions, head and trunk stabilization in space about the pitch axis occurred in children as well as in adults, suggesting an articulated operation of the head-trunk unit. In contrast, during landing, in children and adults, head stabilization in space tended to disappear while trunk stabilization in space was still present, suggesting an en bloc operation of the head-trunk unit. Similarly, pelvis stabilization in space about the roll axis occurred in all subjects during both flight and landing under unipedal conditions, where lateral balance control is of primary importance. Taken together, these results suggest that head stabilization in space is phase dependent, while trunk stabilization is phase independent. The trunk, including the pelvis, may thus constitute a stable reference frame from which anteroposterior and lateral balance control is organized during hops. 2) For head-trunk coordination, whatever the component of rotation, the two groups of children differed from adults, but did not differ from each other, suggesting that, while jumping, the transition between 6 and 7 years of age in the organization of balance control takes place in the coordination of the lower limbs during the preparatory phase of the take-off. Show more

Keywords: development, jumps, head and trunk stabilization, lateral and anteroposterior equilibrium, kinematic analysis, humans

DOI: 10.3233/VES-1997-72-306

Citation: Journal of Vestibular Research, vol. 7, no. 2-3, pp. 145-160, 1997

Authors: Bloomberg, Jacob J. | Peters, Brian T. | Smith, Shannon L. | Huebner, William P. | Reschke, Millard F.

Article Type: Research Article

Abstract: During locomotion, angular head movements act in a compensatory fashion to oppose the vertical trunk translation that occurs during each step in the gait cycle. This coordinated strategy between head and trunk motion serves to aid gaze stabilization and perhaps simplifies the sensory coordinate transformation between the head and trunk, allowing efficient descending motor control during locomotion. Following space flight, astronauts often experience oscillopsia during locomotion in addition to postural and gait instabilities, suggesting a possible breakdown in head-trunk coordination. The goal of the present investigation was to determine if exposure to the microgravity environment of space flight induces alteration …in head-trunk coordination during locomotion. Astronaut subjects were asked to walk (6.4 km/h, 20 s trials) on a motorized treadmill while visually fixating on a centrally located earth-fixed target positioned either 2 m (FAR) or 30 cm (NEAR) from the eyes. In addition, some trials were also performed during periodic visual occlusion. Head and trunk kinematics during locomotion were determined with the aid of a video-based motion analyzing system. We report data collected preflight (10 days prior to launch) and postflight (2 to 4 hours after landing). The coherence between pitch head and vertical trunk movements during gaze fixation of both FAR and NEAR targets was significantly reduced following space flight indicating decreased coordination between the head and trunk during postflight locomotion. Astronauts flying on their first mission showed greater alterations in the frequency spectra of pitch head movements as compared to their more experienced counterparts. These modifications in the efficacy of head movement control may account for the reported disruption in gaze performance during locomotion and may contribute to postflight postural and gait dysfunction. Show more

Keywords: head-trunk coordination, locomotion, space flight, human subjects

DOI: 10.3233/VES-1997-72-307

Citation: Journal of Vestibular Research, vol. 7, no. 2-3, pp. 161-177, 1997

Authors: Takahashi, Masahiro | Ogata, Michihiko | Miura, Masako

Article Type: Research Article

Abstract: In order to clarify the significance of motion sickness in the vestibular system, we compared the findings of experimental motion sickness between different kinds of subjects, some of which were already reported. Subjects were healthy adults, healthy children between the ages of 4 and 15 years, and patients with congenital and acquired labyrinthine loss. They were asked to walk while wearing horizontally and vertically reversing goggles. Equilibrium ataxia as well as motion sickness were evoked by horizontal reversal, but not by vertical reversal in healthy subjects. Kindergarten children exhibited severe ataxia, but little nausea. The frequency of severe ataxia decreased …during growth, inversely as the frequency of nausea syndrome increased. Although a patient with acquired loss became severely ataxic, a patient with congenital loss did not show any ataxia at all. The present study suggests that vestibular cues are indispensable to the ego-spatial relationship in the brain, and once the ego–spatial relationship becomes inadequate, discomfort acts as a safety device to brake uncontrollable actions. Then, perception of the outer world may automatically adjust voluntary actions by affecting motor commands. The importance of visual cues for representing an alternative framework may differ between congenital and acquired labyrinthine loss. Show more

Keywords: motion sickness, spatial orientation, children, labyrinthine loss

DOI: 10.3233/VES-1997-72-308

Citation: Journal of Vestibular Research, vol. 7, no. 2-3, pp. 179-187, 1997

Authors: Allum, J.H.J. | Gresty, M. | Keshner, E. | Shupert, C.

Article Type: Review Article

Abstract: The assumption that the CNS regulates head stability during human balance corrections is explored in this review (an outgrowth of discussions initiated during the Head/Neck meeting held in Vail, Colorado, USA, July 1995). Two major questions were considered. First, how do the vestibulocollic (VCR) and cervicocollic (CCR) reflexes interact with intrinsic mechanical properties of the head neck system to control head position during balance corrections? Second, how is this interaction affected by factors such as vestibular loss, aging, and changes in behavioral goals or central set? The authors conclude that head velocities observed during balance corrections depend to a large …extent on the movements of the head–neck mass-viscoelastic system whose properties could be altered by cocontracting the neck muscles. For experiments involving stance perturbations, much of the corrective response in neck muscles appeared to be triggered by trunk and leg proprioceptive signals, and a major role for the VCR was not established. Evidence consistent with a role for the vestibular system was found in other experimental paradigms in which the head was perturbed directly. In these paradigms the VCR modulates the amplitude of functionally stabilizing responses and damps mechanically induced instability of the head and neck. Show more

Keywords: head movements, balance corrections, vestibulocollic reflex, cervicocollic reflex, postural control, neck muscles

DOI: 10.3233/VES-1997-72-309

Citation: Journal of Vestibular Research, vol. 7, no. 2-3, pp. 189-218, 1997

Authors: Graf, W. | Keshner, E. | Richmond, F.J.R. | Shinoda, Y. | Statler, K. | Uchino, Y.

Article Type: Research Article

Abstract: Extensive information has been accumulated over the past several years about the head-neck sensory-motor system, in particular that relating to cats. Using still x-ray and cineradiographic analysis, the skeletal geometry of head–neck posture in three dimensions—when an animal is resting, actively orienting, or locomoting—is described. From these descriptions, cervical, vertebral, and craniocervical joint biomechanics for all three rotational dimensions are quantified. These behavioral data on muscle and skeletal movements have been incorporated in a biomechanical, functional anatomical model of the head-neck movement system. Individual as well as groups of neck muscles have been measured in detail and their kinematics determined. …The role of a number of these muscles will be described for several reflex and voluntary behavioral contexts, including muscle co-contractions. Having established how each movement is accomplished, the neuronal sensory-motor reflex basis of head–neck system stabilization in space is addressed. The vestibular system is largely responsible for acquisition and maintenance of upright posture. The bilateral semicircular canals (horizontal, anterior, posterior) and otoliths (sacculus, utriculus) feed information differentially to specific neck muscles: these connections are reviewed with regard to the origin of the reflex arc from each receptor to its destination of specific muscles. Behavioral data from normal animals, and from animals whose vestibular receptor systems are selectively lesioned, will be reviewed to complement the functional interpretation of the sensory–motor transformations. Finally, the requirements for space–time coordinated cat head-neck movements will be synthesized, based on biomechanics, muscle kinematics, canal/otolith connectivity, and selective lesion experiments. Show more

Keywords: head–neck, stabilization, cat, sensory–motor, posture

DOI: 10.3233/VES-1997-72-310

Citation: Journal of Vestibular Research, vol. 7, no. 2-3, pp. 219-237, 1997