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Biomedical subjects

M F Reschke

Publications and source records attributed to M F Reschke.

At least 37 records · Page 2Linked to original sources
PubMed1992

Treatment of motion sickness in parabolic flight with buccal scopolamine.

Treatment of acute motion sickness induced by parabolic flight with a preparation of scopolamine placed in the buccal pouch was investigated. Twenty-one subjects flew aboard a KC-135 aircraft operated by the National Aeronautics and Space Administration (NASA) which performed parabolic maneuvers resulting in periods of 0-g, 1-g, and 1.8-g. Each subject flew once with a tablet containing scopolamine and once with a placebo in a random order, crossover design. Signs and symptoms of motion sickness were systematically recorded during each parabola by an investigator who was blind to the content of the tablet. Compared with flights using placebo, flights with buccal scopolamine resulted in significantly lower scores for nausea (31%-35% reduction) and vomiting (50% reduction in number of parabolas with vomiting). Side effects of the drug during flight were negligible. We conclude that buccal scopolamine is more effective than a placebo in treating ongoing motion sickness.

Administration, Buccal↗
PubMed1988

Ground-based training for the stimulus rearrangement encountered during spaceflight.

Approximately 65-70% of the crew members now experience motion sickness of some degree during the first 72 h of orbital flight on the Space Shuttle. Lack of congruence among signals from spatial orientation systems leads to sensory conflict, which appears to be the basic cause of space motion sickness. A project to develop training devices and procedures to preadapt astronauts to the stimulus rearrangements of microgravity is currently being pursued. The preflight adaptation trainers (PATs) are intended to: demonstrate sensory phenomena likely to be experienced in flight, allow astronauts to train preflight in an altered sensory environment, alter sensory-motor reflexes, and alleviate or shorten the duration of space motion sickness. Four part-task PATs are anticipated. The trainers are designed to evoke two adaptation processes, sensory compensation and sensory reinterpretation, which are necessary to maintain spatial orientation in a weightless environment. Recent investigations using one of the trainers indicate that self-motion perception of linear translation is enhanced when body tilt is combined with visual surround translation, and that a 270 degrees phase angle relationship between tilt and surround motion produces maximum translation perception.

Adaptation, Physiological↗
PubMed1987

Space motion sickness preflight adaptation training: preliminary studies with prototype trainers.

Preflight training frequently has been proposed as a potential solution to the problem of space motion sickness. The paper considers successively the otolith reinterpretation, the concept for a preflight adaptation trainer and the research with the Miami University Seesaw, the Wright Patterson Air-Force Base Dynamic Environment Simulator and the Visually Coupled Airborne Systems Simulator prototype adaptation trainers.

Adaptation, Physiological↗
PubMed1987

Effects of prolonged weightlessness on self-motion perception and eye movements evoked by roll and pitch.

Seven astronauts reported translational self-motion during roll stimulation 1-3 h after landing following 5-7 d of orbital flight. Two reported strong translational self-motion perception when they performed pitch head motions during entry and while the orbiter was stationary on the runway. One of two astronauts from whom adequate data were collected exhibited a 132 degrees shift in the phase angle between roll stimulation and horizontal eye position 2 h after landing. Neither of two from whom adequate data were collected exhibited increased horizontal eye movement amplitude or disturbance of voluntary pitch or roll body motion immediately postflight. These results are generally consistent with an otolith tilt-translation reinterpretation model and are being applied to the development of apparatus and procedures intended to preadapt astronauts to the sensory rearrangement of weightlessness.

Electrooculography↗
PubMed1987

Effects of proposed preflight adaptation training on eye movements, self-motion perception, and motion sickness: a progress report.

A program has been initiated to develop apparatus and procedures to preadapt astronauts to the sensory rearrangement associated with weightlessness in spaceflight. If space motion sickness is a consequence of adaptation to that sensory rearrangement, preflight training could afford astronauts significant relief from the motion sickness. The preflight adaptation trainer (PAT) was designed to produce rearranged relationships between visual and otolith signals analogous to those experienced in space. Investigations have been undertaken with three prototype trainers. The results indicated that exposure to the PAT sensory rearrangement altered self-motion perception, induced motion sickness, and changed the amplitude and phase of the horizontal eye movements evoked by roll stimulation. However, the changes were inconsistent. Appropriate measures of adaptation and protocols for producing the adaptation efficiently remain to be determined.

Adaptation, Physiological↗
PubMed1987

Reliability of provocative tests of motion sickness susceptibility.

Accurate prediction of space motion sickness is dependent, in part, upon the reliability of terrestrial-based motion sickness susceptibility tests. In the present study, test-retest reliability values were derived from motion sickness susceptibility scores obtained from two successive exposures to each of three tests: 1) Coriolis Sickness Sensitivity Index (CSSI); 2) Staircase Velocity Movement Test (SVMT); and 3) Parabolic Flight Static Chair Test (PSCT). The reliability of the three tests ranged from 0.70 to 0.88. Normalizing values from predictors with skewed distributions improved the reliability. The apparent inconsistency between our finding of high reliability of predictive tests, and previous reports of low correlations between ground-based predictors and space motion sickness may be due to unreliability in assessment of the sickness criterion. Issues of reliability and validity of predictor and criterion measures, and their implications for future development of ground-based predictive tests are discussed in some detail.

Acceleration↗
PubMed1987

The use of the logistic model in space motion sickness prediction.

The one-equation and the two-equation logistic models were used to predict tested subjects' susceptibility to motion sickness in KC-135 parabolic flights using data from other ground-based motion sickness tests. A data set containing data from 6 provocative tests, 2 vestibular function tests, and 1 motion sickness experience questionnaire from 162 subjects was used in this study. The prediction results from the logistic models were compared with those from the previously-used Bayes linear discriminant analysis procedures. The results based on this data set show that the logistic models correctly predicted substantially more cases (an average of 13%) in the data subset used for model building. In the data subset used for model cross-validation, the logistic models correctly predicted 4% and 5% more cases in the prediction of vomit or nonvomit, and of degree of susceptibility, respectively. Overall, the logistic models ranged from 53 to 65% predictions of the three endpoint parameters, whereas the Bayes linear discriminant procedure ranged from 48 to 65% correct for the cross validation sample.

Adult↗
PubMed1986

Vestibulo-spinal response modification as determined with the H-reflex during the Spacelab-1 flight.

Our laboratory at the Johnson Space Center has employed the H-reflex recorded from the soleus muscle as a method of monosynaptic reflex testing in conjunction with vertical linear acceleration to assess modification of utriculo-saccular function induced through prolonged exposure to microgravity. It was hypothesized that exposure to free fall would reduce the necessity for postural reflexes in the major leg muscles, and that postural modification would reflect a change, not in the peripheral vestibular organs, but more centrally. This postural adjustment would reflect a sensory motor rearrangement where otolith receptor input was reinterpreted to provide an environmentally appropriate response. In addition to the H-reflex (which was the only inflight measurement), vestibulo-spinal EMG from the gastrocnemius, and self-motion reports were obtained in response to a sudden earth vertical fall. Preflight, inflight and postflight motion sickness reports were also recorded, and related to the H-reflex data. The results indicated that early inflight H-reflex amplitude was similar to that recorded preflight, but that measurements obtained later in the flight (day seven) did not show a change in potentiation as a function of the different drop to shock intervals. Immediate postflight H-reflex response in three of the four astronauts tested showed a rebound effect. Postflight gastrocnemius EMG in response to the sudden fall did not show a significant change from preflight values. However, one crewman who was tested early postflight did show an increase in EMG activity in response to the sudden fall. This immediate postflight effect returned to baseline rapidly. Self-motion perception obtained inflight suggested that the early inflight drops were perceived like those preflight. Drops later inflight were described as sudden, fast, hard and translational in nature. Immediately postflight the drops were perceived like those late inflight, and the astronauts said that they did not feel as though they were falling, rather the floor came up to meet them. Post hoc peak H-reflex amplitude, both preflight and postflight was related to inflight space motion sickness.

Humans↗
PubMed1986

Dynamic posture analysis of Spacelab-1 crew members.

Dynamic posture testing was conducted on the science crew of the Spacelab-1 mission on a single axis linear motion platform. Tests took place in pre- and post-flight sessions lasting approximately 20 min each. The pre-flight tests were widely spaced over the several months prior to the mission while the post-flight tests were conducted over the first, second, fourth, and sixth days after landing. Two of the crew members were also tested on the day of landing. Consistent with previous postural testing conducted on flight crews, these crew members were able to complete simple postural tasks to an acceptable level even in the first few hours after landing. Our tests were designed to induce dynamic postural responses using a variety of stimuli and from these responses, evaluate subtle changes in the postural control system which had occurred over the duration of the flight. Periodic sampling post-flight allowed us to observe the time course of readaptation to terrestrial life. Our observations of hip and shoulder position, when subjected to careful analysis, indicated modification of the postural response from pre- to post-flight and that demonstrable adjustments in the dynamic control of their postural systems were taking place in the first few days after flight. For transient stimuli where the platform on which they were asked to stand quickly moved a few centimeters fore or aft then stopped, ballistic or open loop 'programs' would closely characterize the response. During these responses the desired target position was not always achieved and of equal importance not always properly corrected some 15 seconds after the platform ceased to move. The persistent observation was that the subjects had a much stronger dependence on visual stabilization post-flight than pre-flight. This was best illustrated by a slow or only partial recovery to an upward posture after a transient base-of-support movement with eyes open. Postural responses to persistent wideband pseudorandom base-of-support translation were modeled as time invarient linear systems arrived at by Kalman adaptive filter techniques. Derived model parameters such as damping factor and fundamental frequency of the closed loop system showed significant modification between pre- and post-flight. This phenomenon is best characterized by movement of the poles toward increasing stability. While pre-flight data tended to show shoulders and hips moving in phase with each other, post-flight data showed a more disjoint behavior.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗
PubMed1985

Otolith tilt-translation reinterpretation following prolonged weightlessness: implications for preflight training.

Observations with three astronauts yielded two major findings. First, perceived self-motion during sinusoidal roll differed immediately postflight from preflight. Between 70 and 150 min after landing, roll was perceived primarily as linear translation. Secondly, more horizontal eye movement was elicited by roll stimulation immediately postflight relative to both preflight and later postflight observations. These results support an "otolith tilt-translation reinterpretation" hypothesis, which has clear implications for understanding astronaut reports of space motion sickness during the early period of orbital flight. A proposal for "prophylactic adaptation training" which may provide preflight adaptation to weightlessness, derives from this research.

Adaptation, Physiological↗
PubMed1984

Vestibulospinal reflexes as a function of microgravity.

The idea that sustained microgravity will result in altered otolith input requiring a modification of postural control was explored by using the pathway that links the otolith organs and spinal motoneurons. Two related methods were used. First, the Hoffmann reflex was used to measure at specific times the excitability of the soleus-spinal motoneuron pool during a brief unexpected linear acceleration. Second, extensive dynamic postural testing with a moving platform was done before and after flight. The Hoffmann reflex amplitude, reflecting otolith-modulated motoneuron sensitivity, was low in flight after adaptation, and its postflight potentiation may have been dependent on rate of adaptation. The strength of inflight motion sickness symptoms was related to postflight Hoffmann reflex amplitude. Dynamic posture tests showed significant deviations from the results obtained before flight. The strategy used for balance on the moving platform was modified, and the behavior of the subjects suggested a decrease in awareness of the direction and magnitude of the motion.

Electromyography↗
PubMed1983

Transdermal scopolamine in the prevention of motion sickness: evaluation of the time course of efficacy.

This study evaluated the time course of efficacy of transdermal scopolamine in the prevention of motion sickness induced by exposure to coriolis stimulation in a rotating chair. We measured levels of efficacy, quantified side effects and symptoms, and determined inter- and intra-subject variability following use of transdermal scopolamine. The response to transdermal scopolamine was highly variable, although overall we recorded a 40% improvement (p less than 0.05) in test scores 16-72 h after application of the transdermal system. This variability could not be explained solely by the levels of scopolamine present in the blood. The improvement was not due to the artifactual repression by scopolamine of selected symptoms of motion sickness. An unexpectedly high incidence of side effects was reported. It was concluded that the therapeutic use of transdermal scopolamine be evaluated individually and that individuals be cautioned that subsequent usage may not always be effective.

Administration, Topical↗
PubMed1978

Locomotor dysfunction after surgical lesions in the unilateral vestibular nuclei region in squirrel monkeys.

The present experimental results in squirrel monkeys indicated that the performance of psycho-physically advanced locomotor task (squirrel monkey rail test) was severely impaired after the placement of the medium to relatively large surgical lesions in the unilateral vestibular nuclei area, and therefore, confirmed that this brain-stem structure is essential for the signal relay and/or input coordination. The severest locomotor disability was found 10-14 days after the surgery; thereafter, squirrel monkeys showed very gradual and only limited degree of performance recovery. The post-ablative performance levels were no better than 1/5 of their pre-ablative performance levels.

Animals↗
PubMed1977

Effect of otolith end organ ablation on pendular rotation nystagmus in squirrel monkeys.

Damped pendular rotation nystagmus was studied in squirrel monkeys before and after otolith end organ ablation (two-stage operations). After each operation, the nystagmic slow phase eye speed toward the operated side was reduced (to about 73% of that before the operation) and that to the non-operated side did not show any marked change. A few subjects showed spontaneous nystagmus with amphetamine administration but only in dark (could not be found in light) immediately after the operation, and it disappeared rapidly. Therefore, this post-ablative reduction of the slow phase eye speed is considered to result from the loss of inputs from the otolith end organs.

Amphetamine↗