Journal of Vestibular Research - Volume 13, issue 1

Authors: Anker, A.R. | Ali, A. | Arendt, H.E. | Cass, S.P. | Cotter, L.A. | Jian, B.J. | Tamrazi, B. | Yates, B.J.

Article Type: Research Article

Abstract: Prior work has shown that the vestibular system contributes to regulating activity of upper airway muscles including the tongue protruder muscle genioglossus. The goal of the present experiments was to determine whether electrical vestibular stimulation could potentially be used to alter genioglossal activity in awake animals. Six adult cats were instrumented for recording of EMG activity from genioglossus, abdominal musculature, and triceps. In addition, a silver ball electrode was implanted on the round window for stimulation of vestibular afferents. Subsequently, stimulation and recordings were conducted while animals were awake. In all cases, stimulation using single shocks or trains of pulses …> 100 μA in intensity produced responses in all muscles, including genioglossus. The latency of the genioglossal response was approximately 12 msec, and delivering continuous current trains to the labyrinth chronically elevated the muscle's activity. Although a number of muscles were affected by the stimulus, animals experienced no obvious distress or balance disturbances. Vestibular stimulation remained effective in producing genioglossal responses until experiments were discontinued 1–2 months following onset. These data suggest that electrical vestibular stimulation could potentially be used therapeutically to alter upper airway muscle activity. Show more

Keywords: upper airway, tongue musculature, respiration, vestibular system

DOI: 10.3233/VES-2003-13101

Citation: Journal of Vestibular Research, vol. 13, no. 1, pp. 1-8, 2003

Authors: Russell, Noah A. | Horii, Arata | Smith, Paul F. | Darlington, Cynthia L. | Bilkey, David K.

Article Type: Research Article

Abstract: In order to investigate whether bilateral peripheral vestibular lesions cause long-term impairment of spatial learning, rats were tested in a reference memory radial arm maze learning task at least 5 weeks following a bilateral labyrinthectomy (BL) or sham control lesion. All control rats reached criterion (i.e., 1 error or less, averaged across 7 trials for 3 consecutive days of training) but only 4 of the 8 BL rats had reached criterion by day 21 of the training sessions. The control rats reached criterion more quickly than the lesioned rats (Control, 7.0 ± 0.63 days, Lesioned, 15.8 ± 1.4 days, t …10 = 5.84 , p < 0.0001). This difference resulted from the greater number of errors made by the BL animals. However, the latency to respond was comparable as a result of the increased locomotor activity of the BL group (i.e., ’hyperkinesis), and the overall rate of acquisition of the task, as indicated by analysis of the exponential decrease in errors over the entire training period, was not significantly different between the 2 groups. The results of this study demonstrate that BL in rats produces long-term changes in performance in a spatial reference memory task, which are not simply due to the inability to move but may relate to the way that the brain uses vestibular information to create spatial representations and determines behavioural strategies on the basis of these representations. Show more

Keywords: peripheral vestibular lesions, bilateral labyrtinthectomy, spatial learning

DOI: 10.3233/VES-2003-13102

Citation: Journal of Vestibular Research, vol. 13, no. 1, pp. 9-16, 2003

Authors: Nowé, Vicky | Wuyts, Floris L. | Hoppenbrouwers, Mieke | Van de Heyning, Paul H. | De Schepper, Arthur M. | Parizel, Paul M.

Article Type: Research Article

Abstract: Knowledge of the exact distance between the utricles is important in new vestibular tests, such as the unilateral centrifugation (UC) test for the unilateral examination of the utricles. During this test, subjects are rotated at constant velocity and simultaneously laterally displaced along an interaural axis so that one labyrinth becomes aligned with the axis of rotation. When the axis of rotation crosses precisely through one labyrinth, only the opposite labyrinth is stimulated. To achieve this setup, precise knowledge of the interutricular distance is needed. The purpose of this study is to investigate the correlation between the interutricular distance (IUD), measured …on T2-weighted magnetic resonance images, and specific external measures of head dimensions such as distance nasion-inion, intermastoid distance (IMD), distances between the temporomandibular joints and between the lateral margins of the orbits. Data have been collected in a series of 50 subjects (25 men and 25 women). On MR images we found a mean IUD of 7.22 cm (S D = 0.42 cm). There was a strong correlation between the IUD measured on MR images and the intermastoid distance. A linear combination of the IMD, nasion-inion distance and height of the subjects could predict the IUD very satisfactory (R=0.85, adjusted R 2 = 0.723 ). We also determined a measure of eccentricity of the vestibular labyrinths. The 95% prediction interval for the asymmetry appeared to be less than 4.3%. Show more

DOI: 10.3233/VES-2003-13103

Citation: Journal of Vestibular Research, vol. 13, no. 1, pp. 17-23, 2003

Authors: Radtke, Andrea | Popov, Konstantin | Bronstein, Adolfo M. | Gresty, Michael A.

Article Type: Research Article

Abstract: We examined the hypothesis that vestibular signals may exert a rapid control on the heart adjusting cardiovascular function to maintain homoestasis during changes in body posture. Short- and long-latency effects of vestibular stimulation on heart rate (HR), systolic blood pressure (SP), diastolic pressure (DP) and digital blood flow (BF) were studied in fourteen normal controls (NC) and nine labyrinthine-defective subjects (LDS) exposed to abrupt head accelerations. Subjects lay supine with their head suspended in a sling whose 'release' was triggered at delays of 170 ms and 570 ms after an R-spike of the ECG. Release caused the head to fall …with an acceleration ∼0.8 g for approximately 140 ms. Three additional NC underwent head drops at 170 ms, 370 ms, 470 ms and 570 ms to determine response latencies with precision. In NC, the short-latency response to head drops timed 170 to 470 ms after an R-spike was to shorten the time to the next R-spike in comparison to pre-drop heartbeat cycles. Drops at 570 ms delay shortened only the succeeding post-stimulus RR-interval. In LDS, head drops timed 170 ms after a heartbeat failed to shorten the ongoing cardiac cycle. For both delays only the succeeding cardiac cycle was significantly shortened. In all subjects, SP rose slightly by approximately 1–3% and BF decreased by 7–24% after 3–4 heartbeats post-drop. The results are evidence for an excitatory vestibulo-cardiac reflex in man which accelerates heart rate at a latency circa 500–600 ms. SP and BF are affected at longer latencies of several heart beats. A delayed increase of heart rate in response to postural challenge may contribute to the autonomic distress experienced by patients with vestibular loss. Show more

Keywords: vestibular reflex, cardiac reflex-autonomic function, heart rate control

DOI: 10.3233/VES-2003-13104

Citation: Journal of Vestibular Research, vol. 13, no. 1, pp. 25-37, 2003

Authors: Stål, F. | Fransson, P.A. | Magnusson, M. | Karlberg, M.

Article Type: Research Article

Abstract: The aim of this study was to investigate the significance of information from the plantar cutaneous mechanoreceptors in postural control and whether postural control could compensate for reduced cutaneous information by adaptation. Sixteen healthy subjects were tested with eyes open or eyes closed with hypothermic and normal feet temperature during posturography where body sway was induced by vibratory proprioceptive stimulation towards both calf muscles. The hypothermic anesthesia was obtained by cooling the subject's feet in ice water for 20 minutes. Body movements were evaluated by analyzing the anteroposterior and lateral torques induced towards the supporting surface by a force platform …during the posturography tests. The reduction of cutaneous sensor information from the mechanoreceptors of the feet significantly increased the vibration-induced torque variance mainly in the anteroposterior direction. However, the effects of disturbed mechanoreceptors information was rapidly compensated for through postural adaptation and torque variance was in level with that without anesthesia within 50 to 100 seconds of stimulation, both when standing with eyes open and eyes closed. Our findings suggest that somatosensory input from mechanoreceptors in the foot soles contribute significantly in maintaining postural control, but the sensory loss could be compensated for. Show more

Keywords: postural control, sensation, hypothermic anesthesia, adaptation

DOI: 10.3233/VES-2003-13105

Citation: Journal of Vestibular Research, vol. 13, no. 1, pp. 39-52, 2003

Authors: Zalewski-Zaragoza, Robert Aureo | Viirre, Erik Scott

Article Type: Research Article

Abstract: Persons who experience vertigo often describe their symptoms as a sensation of oscillations. Based on such a description, a pilot study was performed to determine if the frequency of the vertigo sensation could be quantified in a manner analogous to tone matching in tinnitus treatment. Fifteen subjects were tested using a virtual image system that consisted of a head mounted display showing a scene that oscillated horizontally or vertically at an adjustable frequency. Subjects were asked to adjust the direction and frequency to match their typical vertigo sensation. Results show that most persons with chronic vertigo had symptoms that could …be realistically simulated by vection induced by the oscillating scene and that matched to a consistent specific frequency. They reported an average frequency of 1.09 Hz (range 0.27 to 3.3 Hz, SD 0.25). The large majority (13 out of 15) matched to a horizontal stimulus. Subjects that gave particularly high subjective ratings of the similarity of the motion sensation (7–8 out of 10) from the vection to their vertigo had lower frequency matches (average 0.61 +/- 0.25). Repeated measurements in 4 subjects 8 to 27 days later showed consistent results. This vertigo measurement technique may be used in the future to assess the ability of vestibular rehabilitation to reduce chronic vertigo. Identification of a specific frequency of chronic vertigo may be important in the specification of rehabilitation exercises. Show more

Keywords: vertigo, frequency, vection, head mounted display

DOI: 10.3233/VES-2003-13106

Citation: Journal of Vestibular Research, vol. 13, no. 1, pp. 53-56, 2003