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Biomedical subjects

R J von Baumgarten

Publications and source records attributed to R J von Baumgarten.

At least 19 recordsLinked to original sources
PubMed1996

Evidence of sensory conflict and recovery in carp exposed to prolonged weightlessness.

BACKGROUND: Evidence in support of the sensory conflict hypothesis for space motion sickness (SMS) is still needed. HYPOTHESIS: We hypothesized that sensory conflict and recovery processes should be demonstrated in intact fish during initial days of microgravity exposure, as a disturbance and restoration of the dorsal light response (DLR; a functional model of visual-graviceptor interaction), respectively. We also expected that this would be true in an otolith-removed fish if it had been fully compensated for dysfunction before the exposure. METHODS: The DLR of carp (Cyprinus carpio) was examined intermittently during the 8-d mission of Spacelab-J. Two carp, normal and labyrinthectomized (LB), made the flight. RESULTS: In the normal carp, the DLR was unstable for the first 3 d inflight but gradually recovered thereafter. The recovery was characterized by gradual restoration of the DLR tilt speed. The LB fish whose otoliths had been removed 2 mo before the flight maintained DLR at the first inflight test session (22 h after launch), but DLR was disrupted at 2 d as in normal fish. The recovery process could not be evaluated in this fish, because the EEG cable which was attached to the fish for supplementary study became tightly twisted and thus immobilized the fish for the remainder of the experiment. CONCLUSION: These findings provided additional evidence in fish for sensory-motor disorder and readjustment during the early phase of microgravity, thus supporting the sensory conflict hypothesis for SMS.

Animals↗
PubMed1994

Ground based eccentric chair experiments.

Two subjects were rotated eccentrically in a manner described before. In contrast to a normal control group settings of a luminous line to the subjective vertical were almost unrelated to the gravitoinertial summation vector of gravity and centrifugal forces about four weeks before and totally so shortly after space flight. Only after four days post flight had passed a noticeable relation to the gravitoinertial vector re-established itself in the one subject which actually flew. The correspondence became normal six days after flight. Since there were no clinical abnormalities evident in the subjects, it is suggested, that both subjects suppressed their vestibular information presumably as an effect of vestibular deconditioning training before flight. In addition as a consequence of the flight experience one subject continued to ignore it several days after the flight.

Gravity Sensing↗
PubMed1994

Ocular torsion during microgravity on a space mission in 1992.

On a space mission in 1992 we investigated the effect of pure neck receptor stimulation on eye roll position in space. To do this, we used the flash afterimage method. We found that eye rotations in static tilted head positions are absent in weightlessness. This suggests that in microgravity the neck position receptors do not contribute to a measurable extent to static OCR.

Adult↗
PubMed1994

Space experiment using large-sized fish: in case of carp in Spacelab-J mission.

Two carp of 26 cm in size, intact and otolith-removed (LB), were flown on the Spacelab-J for 8 days in September 12-20, 1992. Light-dependent reaction to alternating direction of illumination was recorded for 10 min twice a day together with the cerebellar EEG activity, on 2 days before the launch, during the flight and for 4 days after the landing, in same fish chamber. Reproducing the video image, it was revealed that both carp were healthy during the mission, but the LB fish was almost immobilized from the 3rd test session (48 hours in flight) by tight twisting of the EEG cable. Both fish after landing tended to stay still on the bottom of the fish chamber. Findings that the body weight reduced remarkably in both fish and that nitrite and nitrate levels of the fish water were usually high, suggested that the fish metabolism might have been enhanced during the flight.

Animals↗
PubMed1992

Clinical verification of a unilateral otolith test.

In a previous study we reported promising results for a new test to differentiate in vivo unilateral otolith functions. That study pointed to a need for further validation on known pathological cases. In this presentation we will detail the results gathered on a group of clinically verified vestibular defectives (verum) and a normal (control) group. The subjects in the verum group were former patients of the ENT clinic of the university hospital. These subjects had usually suffered from neurinoma of the VIIth cranial nerve or inner ear infections. All had reguired surgical intervention including removal of the vestibular system. The patients were contacted usually two or more years postoperatively. A group of students from the pre- and clinical phase of medical training served as control. Both groups were subjected to standardized clinical tests. These tests served to reconfirm the intra- or postoperative diagnosis of unilateral vestibular loss in the verum group. In the control group they had to establish the normalcy of the responses of the vestibular system. Both groups then underwent testing on our eccentric rotary chain in the manner described before. Preliminary results of the trials indicate that this test may indeed for the first time offer a chance to look at isolated otolith apparati in vivo.

Adult↗
PubMed1991

Transition from self tilt to object tilt during maintained lateral tilt in parabolic flight.

19 young healthy subjects were subjected to parabolic rollercoaster flight. A horizontal luminous line was seen by the subjects in a headfixed goggle device. During the hypergravic phases of parabolic flight the luminous line seemed to rotate into and during the hypogravic phase against the direction of static head tilt. Ocular counter rotation and activity of the neck position receptors cannot explain these subjective rotations. We conclude that information from the otolith system, converging with visual information within the brain, dislocated the headfixed visual target line. While the retinal image of the luminous line remains unchanged, loading and unloading the otoliths in parabolic flight changes the sensation of self tilt into object tilt, hereby subjectively rotating visual targets such as the luminous line.

Eye Movements↗
PubMed1987

General remarks on the role of the vestibular system in weightlessness.

Different methods are described to experimentally achieve weightlessness. Since the function of the otolith system depends on the presence of contact forces opposing gravity, it is disabled in weightlessness and may send misleading positional information to the brain. Without the contributions of the otolith system it is difficult in space to distinguish self-motion from object motion. Furthermore, the disintegration of information from the neck position receptors from those of the otolith system can lead to additional illusory positional sensations. Since the function of the semicircular canal system in previous space flights was found to be essentially undisturbed, the vestibular experiments in the Spacelab-D1 missions concentrated more on the otolith system. The function of other orientational cues from the visual system, the semicircular canal system and proprioception can be studied in isolation from the otolith system in space. In the Spacelab-D1 mission, the space vestibular sled was used as a device for studying linear acceleration. The vestibular helmet "permitted" video and EOG recordings of all eye movements and provided caloric and optokinetic stimulation. Various factors contributing to static and dynamic forms of space sickness are identified.

Humans↗
PubMed1986

European vestibular experiments on the Spacelab-1 mission: 1. Overview.

During the flight of Spacelab-1 a series of vestibular experiments was performed on the crew by a group of European investigators. Control experiments were carried out on the same subjects pre- and postflight. The tests included caloric stimulation of the ears, threshold measurements of response to linear acceleration, motion sickness provocative stimuli, vestibulo-ocular reflexes during linear and angular stimulation, estimation of the subjective vertical (luminous line measurements) and static ocular counterrotation at various tilt angles. The caloric experiment proved the existence of a nonthermoconvective mechanism of caloric nystagmus in space. Most of the other test results point to a greater dependence on visual and somatosensory than on otolith cues in the microgravity environment. Some results, in particular the raised threshold to perception of linear acceleration in flight and the temporary reduction of ocular counterrotation at lateral tilts postflight, suggest a decreased gain of the otolith system as a possible effect of space vestibular adaptation.

Acceleration↗
PubMed1982

Dependence of motion sickness in automobiles on the direction of linear acceleration.

Thirty-eight normal volunteers were tested in an ambulance car while being accelerated in one of the following positions: (1) sitting upright facing forward in the car, (2) lying supine on a stretcher head forward, (3) supine position head backward. Consecutive short period of negative horizontal acceleration (0.7-0.95 g) were achieved by brisk braking manoeuvres of the car, followed by weak reacceleration (0.15 g). Motion sickness symptoms were observed and recorded after each experiment using a special motion sickness scaling index which was weighted according to the strength of any particular symptom. The results indicate that horizontal linear acceleration in a car, such as experienced during multiple breaking manoeuvres, is an effective motion sickness provoking stimulus. Negative X-axis stimulation is more nauseogenic then acceleration in the Z-axis stimulation is more nauseogenic then acceleration in the Z-axis of the body.

Acceleration↗
PubMed1980

Physiological response to hyper- and hypogravity during rollercoaster flight.

Healthy male subjects--26--were flown in a Lear jet aircraft through rollercoaster and parabolic weightlessness flight. Eye movements, respiration, and blood volume pulse were recorded on magnetic tape. The same subjects underwent a battery of five vestibular tests in the laboratory on the ground. One subject in each flight was flown in an upright position, the other in a 90 degree foreward tilted head position. The foreward tilted subjects always reported motion sickness earlier and after fewer rollercoaster manoeuvres than the upright sitting subjects. It is concluded that the susceptibility to changes of X-axis acceleration is higher than to changes of Z-axis acceleration. Correlation was found between the ability to estimate the subjective vertical (modified Müller-Aubert-test), optokinetic nystagmus asymmetries, and susceptibility to rollercoaster flight sickness.

Adult↗
PubMed1979

A model for vestibular function in altered gravitational states.

During evolution, the vestibular organ was made to serve mainly two purposes: 1) to guide eye movements during sharp turns, so that the point of fixation in the visual field can be kept steady, a function accomplished by the semicircular canal system and 2) to indicate the terrestrial vertical, so that upright posture and gait can be maintained even in the dark. The otolith system serves the latter purpose. Since the function of the semicircular canal system does not depend on gravity, it is not grossly disturbed by gravitational levels different from 1 g. The proper function of the otolith system depends entirely on the presence of a gravitational force vector of 9.8/m/sec2 directed towards the center of the earth. This system therefore malfunctions when the amplitude of the combined gravito-inertial load is different from 1 g and also when the direction of the sensed gravitational pull is "contaminated" by additional inertial reactive forces as during horizontal acceleration. The effect of such inertial stimulations is probably even stronger in a weightless environment, in which case the background stimulation of terrestrial gravity is absent. Moreover, minor mass differences between the otolithic membranes of the left and right inner ear, even if well compensated on the ground, might lead to malcompensation in weightlessness as well as in hypergravity. A hypothetical model is developed to describe in the central nervous system compensating mechanisms in hypo- and hypergravitational states. The "space-sled" is introduced as a new research tool and recommendations are made for a prophylactic training regimen to reduce or prevent space sickness.

Adaptation, Physiological↗
PubMed1978

Effect of prehatching weightlessness on adult fish behavior in dynamic environments.

At 16-17 months of age, three groups of fish from the embryonated eggs in the ASTP killifish experiment were subjected to postflight tests consisting of rapidly changing environments. It was found that the group of fish with the least amount of development at orbital insertion (A-32) had a decreased rheotropism for both the moving background and the rotating water current tests when compared to ground control fish. Exposure to parabolic aircraft flight conditions revealed that the A-32 fish were less disoriented during zero gravity periods and were hypersensitive to high-gravity periods. These results suggested a modified vestibular competency due to a 9-d prehatching weightlessness exposure.

Adaptation, Physiological↗
PubMed1975

Effects of prolonged weightlessness on the swimming pattern of fish aboard Skylab 3.

Two fingerling fish and 50 embryonated eggs of (Fundulus heteroclitus) were flown aboard Skylab 3 in a plastic bag aquarium. Videographic picutres were taken with the on-board color-TV camera on flight Days 3 and 22 and video tapes were made for later evaluation on the ground. When observed first after 3 d in orbital weightlessness, both fish swam in tight circles for a considerable fraction of the observed time resembling the "looping behavior" as observed in previous studies with goldfish in parabolic aircraft flight. The frequency of looping diminished slowly after the third day until normal swimming was prevalent. At flight Day 22, both fish swam normally with their backs turned toward the light source. Looping episodes could still be provoked at this time by gentle shaking of the bag aquarium. Of the fish eggs carried aboard, 96% hatched during the mission. The hatch fry displayed normal swimming behavior.

Animals↗