Journal of Vestibular Research - Volume 6, issue 1

Article Type: Other

DOI: 10.3233/VES-1996-6108

Citation: Journal of Vestibular Research, vol. 6, no. 1, pp. I-I, 1996

Authors: Fuller, James H.

Article Type: Research Article

Abstract: Head movement propensity – the pattern of head saccades dependent on methods of target presentation – varies among individuals. The present group of 9 young adults was previously ranked in a visual saccadic task according to this propensity. The present report examines how and why this propensity changes if the saccades are made to auditory targets. 1) Spatially identical, interleaved, auditorily and visually elicited horizontal saccadic gaze shifts (jumps) differed in amplitude and in starting and/or ending position. The jumps were executed in two head movement modes: first, the non-aligned mode was a standard reaction-time single gaze step between two …points. Second, the head-aligned mode required alignment of the head with the fixation (starting) point; thereafter both modes were identical. All results in the auditory task are expressed relative to the visual results. 2) In the non-aligned mode, head movement amplitudes were increased on average by 15% (for example, an 80° jump elicited a 12° larger head movement), and velocity decreased by 12%, reflecting the increased demands of the auditory task. More importantly, the differences between subjects was narrowed; that is, head movement propensity was homogenized in the auditory task. In the visual task, head-movers willingly move their heads off and across the midline, whereas non-movers are unwilling to leave the midline from eccentric starting points or to eccentric ending points. This is called the midline attraction effect and was previously linked to spatial reference frames. The homogenization in the auditory task was characterized by head-movers increasing, and non-movers decreasing, their midline attraction, suggesting altered spatial reference frames. 3) For heuristic purposes, the ideal head-mover is defined by a gain of 1.0 in the visual task, and by external earth-fixed reference frames. Similarly, the ideal non-mover has a gain of 0.0 and has a bias toward body (or some part of the body)-fixed reference frames. In the auditory task these gains (and reference frames) in head-movers and non-movers are homogenized (closer to 0.5), either by the participation of the head (movement of the ears in space) in sensory acquisition or by differences in central nervous processing of the two modalities, or both. Show more

Keywords: head saccade, saccadic gain, gaze shift, eye-head coordination

DOI: 10.3233/VES-1996-6101

Citation: Journal of Vestibular Research, vol. 6, no. 1, pp. 1-13, 1996

Authors: Kolev, Ognyan I. | Altaparmakov, Ivan A.

Article Type: Research Article

Abstract: The cardinal symptoms of motion sickness occur in the gastrointestinal system. This study sought to investigate the influence of sickness-provoking motion stimuli on the interdigestive migrating electric complex (IDMEC) of the gastrointestinal system. Thirteen susceptibles and 14 insusceptibles to motion sickness were subjected to intralumenal recording before and after caloric vestibular stimulations. Motion sickness developed in all subjects. The results indicate that there are no significant differences in the IDMECs of susceptibles and insusceptibles in a state of rest; vestibular stimulation changes the duration of IDMEC phases (P < 0.05 and P < 0.01); IDMEC changes differ slightly between susceptibles …and insusceptibles; motion stimuli induce simultaneous nonpropulsive spike activity, which is more frequent in susceptibles (P < 0.01); vestibular stimulation applied during phase III of IDMEC does not provoke vomiting in susceptibles. Show more

Keywords: interdigestive, migrating electric complex, caloric vestibular stimulation, motion sickness

DOI: 10.3233/VES-1996-6102

Citation: Journal of Vestibular Research, vol. 6, no. 1, pp. 15-21, 1996

Authors: de Graaf, Bernd | de Roo, A. Julius

Article Type: Research Article

Abstract: Previous investigations suggest strong similarities between aftereffects of an 1.5-hour 3 gx centrifuge run (Sickness Induced by Centrifugation; SIC) and the Space Adaptation Syndrome (SAS). Head movements proved to be especially nauseogenic in both cases. Until recently, during SIC experimentation, the performance of head movements was not adequately operationalized, which hampered a statistical evaluation. For this purpose, a test was designed by which head movements in four directions (left, right, up, and down) were provoked and registered, once before and once after a 1-h 3 g centrifuge run. Subjects had to execute these head movements in order to perform …well on a psychomotor task. The results indicate that the test described is sensitive in discriminating between subjects who are seriously affected after a long duration centrifugation and those who are not. Because differences in performance were found only on those parts of the task in which head movements were involved, objective evidence is obtained in favour of a vestibular cause in the etiology of SIC. Show more

Keywords: hyper G-load, head movements, motion sickness, psychomotor task

DOI: 10.3233/VES-1996-6103

Citation: Journal of Vestibular Research, vol. 6, no. 1, pp. 23-29, 1996

Authors: Cohen, Helen

Article Type: Research Article

Abstract: Few papers describe illusions of motion after sailing for which subjects do not seek medical assistance. After sailing on a square-rigged ship for five-hour periods subjects were surveyed about the incidence, intensity, and quality of such illusions. Even on a calm day, 20% to 41% of the crew experienced post-sailing vertigo, but it only occurred among the nonprofessional sailors. This phenomenon is characterized by extinction with repeated exposure, a lag time to onset of about two hours, brief duration, and occurrence in enclosed visual surrounds. These data are similar to vestibular habituation and suggest that some central vestibular mechanisms may …be involved. Show more

Keywords: habituation, mal de debarquement, vestibular

DOI: 10.3233/VES-1996-6104

Citation: Journal of Vestibular Research, vol. 6, no. 1, pp. 31-35, 1996

Authors: Karlberg, Mikael | Johansson, Rolf | Magnusson, Måns | Fransson, Per-Anders

Article Type: Research Article

Abstract: Useful clinical tests are lacking for the controversial entity “cervical vertigo”. In earlier studies patients assumed to suffer from cervical vertigo or dizziness manifested disturbed postural control as compared to healthy subjects, but were hard to distinguish from patients with other balance disorders. Using posturography in which stance was perturbed by a vibratory stimulus applied towards the calf muscles, we studied 16 consecutive patients with recent onset of neck pain and concomitant complaints of vertigo or dizziness, but normal findings at otoneurological examination and electronystagmography; 18 patients with recent vestibular neuritis; and 17 healthy subjects. We performed system identification of …a model of the control of upright human stance, using the vibratory stimulus as input and the recorded body sway as output. According to values for the three normalized parameters of the transfer function of the model (ie, swiftness, stiffness, and damping), cervical vertigo patients were distinguished both from healthy subjects (P < 0.001), and from vestibular neuritis patients (P < 0.001). It was also possible to distinguish the vestibular neuritis group from the group of healthy subjects (P < 0.01). The results show disturbed postural control in patients with cervical vertigo to differ from that in patients with recent vestibular neuritis, and indicate posturographic assessment of human posture dynamics to be a possible future tool for use in diagnosing cervical vertigo. Show more

Keywords: neck, vertigo, vestibular function test, posture

DOI: 10.3233/VES-1996-6105

Citation: Journal of Vestibular Research, vol. 6, no. 1, pp. 37-47, 1996

Authors: Sansom, Andrew J. | Smith, Paul F. | Darlington, Cynthia L.

Article Type: Research Article

Abstract: We describe the use of fentazin anesthesia (0.4 mg/ml fentanyl citrate, 58.3 mg/mL xylazine HCl, and 3.2 mg/mL azaperone, Parnell, New Zealand) for labyrinthine surgery in guinea pigs. Fentazin provides stable surgical anesthesia for approximately 1 hour, rapid recovery from anesthesia following the surgery, and has significant analgesic and anxiolytic properties. Its advantages in comparison to other anesthetics (for example, ketamine HCl) are discussed.

Keywords: labyrinthectomy, guinea pig, fentazin, analgesia, opioid

DOI: 10.3233/VES-1996-6106

Citation: Journal of Vestibular Research, vol. 6, no. 1, pp. 49-52, 1996

Authors: Maki, B.E. | McIlroy, W.E.

Article Type: Short Communication

Abstract: Healthy young adults (n = 39) were asked to perform four different secondary cognitive tasks during quiet unperturbed stance, in order to investigate the influence of physiological arousal and attention distraction on the control of spontaneous postural sway. During each task, postural activity was quantified in terms of center-of-pressure displacement, leg-muscle activation, and ankle and hip rotation. Arousal was monitored via skin conductance, and questionnaires were used to assess state anxiety. Respiratory trunk movements were also recorded, to assess potential arousal-related destabilizing effects, but failed to show a strong association with the postural measures. The nature of the secondary task …affected the postural responses in that subjects tended to lean slightly forward, and exhibited higher levels of activation in tibialis anterior, when performing a mental-arithmetic task. Although this task affected both attention and arousal, the leaning effect was limited to subjects who reported higher levels of anxiety-related autonomic or somatic symptoms during testing, and the degree of leaning was correlated with the level of physiological arousal. A secondary task that diverted attention but did not affect physiological arousal (listening to a spoken-word recording) failed to elicit changes in postural response. These findings suggest that the changes in leaning were associated with task-related changes in physiological arousal, and highlight the need to account for the potentially confounding influence of arousal when studying attentional effects. Given the potential influence on stability, the results also suggest that leaning should be monitored or controlled during balance assessment, particularly when dealing with individuals who may be anxious or afraid of falling. Show more

Keywords: arousal, attention, balance, posture

DOI: 10.3233/VES-1996-6107

Citation: Journal of Vestibular Research, vol. 6, no. 1, pp. 53-59, 1996