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All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Sensitive Quantitative Assessment of Balance Disorders

Computerized dynamic posturography (CDP) has become a standard technique for objectively quantifying balance control performance, diagnosing the nature of functional impairments underlying balance disorders, and monitoring clinical treatment outcomes. We have long used CDP protocols to assess recovery of sensory-motor function in astronauts following space flight. The most reliable indicators of post-flight crew performance are the sensory organization tests (SOTs), particularly SOTs 5 and 6, which are sensitive to changes in availability and/or utilization of vestibular cues. We have noted, however, that some astronauts exhibiting obvious signs of balance impairment after flight are able to score within clinical norms on these tests, perhaps as a result of adopting competitive strategies or by their natural skills at substituting alternate sensory information sources. This insensitivity of the CDP protocol could underestimate of the degree of impairment and, perhaps, lead to premature release of those crewmembers to normal duties. To improve the sensitivity of the CDP protocol we have introduced static and dynamic head tilt SOT trials into our protocol. The pattern of postflight recovery quantified by the enhanced CDP protocol appears to more aptly track the re-integration of sensory-motor function, with recovery time increasing as the complexity of sensory-motor/biomechanical task increases. The new CDP protocol therefore seems more suitable for monitoring post-flight sensory-motor recovery and for indicating to crewmembers and flight surgeons fitness for return to duty and/or activities of daily living. There may be classes of patients (e.g., athletes, pilots) having motivation and/or performance characteristics similar to astronauts whose sensory-motor treatment outcomes would also be more accurately monitored using the enhanced CDP protocol. Furthermore, the enhanced protocol may be useful in early detection of age-related balance disorders.

Paloski, Willilam H.↗
NASA NTRS2006

Architecting Ourselves: Schema to Facilitate Growth of the International Space Architecture Community

This paper develops a conceptual model, adapted from the way research and development non-profits and universities tend to be organized, that could help amplify the reach and effectiveness of the international space architecture community. The model accommodates current activities and published positions, and increases involvement by allocating accountability for necessary professional and administrative activities. It coordinates messaging and other outreach functions to improve brand management. It increases sustainability by balancing volunteer workload. And it provides an open-ended structure that can be modified gracefully as needs, focus, and context evolve. Over the past 20 years, Space Architecture has attained some early signs of legitimacy as a discipline: an active, global community of practicing and publishing professionals; university degree programs; a draft undergraduate curriculum; and formal committee establishment within multiple professional organizations. However, the nascent field has few outlets for expression in built architecture, which exacerbates other challenges the field is experiencing in adolescence: obtaining recognition and inclusion as a unique contributor by the established aerospace profession; organizing and managing outreach by volunteers; striking a balance between setting admittance or performance credentials and attaining a critical mass of members; and knowing what to do, beyond sharing common interests, to actually increase the market demand for space architecture. This paper develops a conceptual model, adapted from the way research-anddevelopment non-profits and universities tend to be organized, that could help amplify the reach and effectiveness of the international space architecture community. The model accommodates current activities and published positions, and increases involvement by allocating accountability for necessary professional and administrative activities. It coordinates messaging and other outreach functions to improve brand management. It increases sustainability by balancing volunteer workload. And it provides an open-ended structure that can be modified gracefully as needs, focus, and context evolve. This organizational model is offered up for consideration, debate, and toughening by the space architecture community at large.

space architecure↗
NASA NTRS2006

Head Tilt Posturography to Enhance Balance Control Assessment for Astronauts: A Case Study

For many years, we have used a standard clinical computerized dynamic posturography (CDP) protocol to assess recovery of integrated sensory-motor function in astronauts returning from space flight. The most reliable indications of postflight crew performance capabilities have been obtained from the sensory organization tests (SOTs) within the CDP protocol, particularly SOTs 5 (eyes closed, surface support sway referenced) and 6 (eyes open, surface support and visual surround sway referenced), which are sensitive to changes in availability and/or utilization of vestibular cues. We have observed, however, that some astronauts exhibiting visible signs of incomplete sensory-motor recovery are able to score within clinical norms on standard SOTs 5 and 6 trials, perhaps as a result of cognitive strategies driven by their naturally competitive natures. To improve the sensitivity of the CDP protocol for assessing recovery of integrated sensory-motor function and fitness to return to duties and/or activities of daily living, we have introduced pitch plane head tilt SOT trials to our protocol. In a preliminary study of 5 short duration (~11day missions) astronauts, we showed that they were unable to maintain balance on landing day when performing dynamic head tilt trials, despite scoring within the clinically normal range on the standard SOT trials. The present case report illustrates the advantages of including head tilt trials for assessing sensory-motor recovery in long duration crewmembers.

Hwang, E. Y.↗
NASA NTRS2010

Calibration Designs for Non-Monolithic Wind Tunnel Force Balances

This research paper investigates current experimental designs and regression models for calibrating internal wind tunnel force balances of non-monolithic design. Such calibration methods are necessary for this class of balance because it has an electrical response that is dependent upon the sign of the applied forces and moments. This dependency gives rise to discontinuities in the response surfaces that are not easily modeled using traditional response surface methodologies. An analysis of current recommended calibration models is shown to lead to correlated response model terms. Alternative modeling methods are explored which feature orthogonal or near-orthogonal terms.

Wind tunnel models↗
NASA NTRS1994

Metabolic Cages for a Space Flight Model in the Rat

A variety of space flight models are available to mimic the physiologic changes seen in the rat during weightlessness. The model reported by Wronski and Morey-Holton has been widely used by many investigators, in musculoskeletal physiologic studies especially, resulting in accumulation of an extensive database that enables scientists to mimic space flight effects in the 1-g environment of Earth. However, information on nutrition or gastrointestinal and renal function in this space flight model is limited by the difficulty in acquiring uncontaminated metabolic specimens for analysis. In the Holton system, a traction tape harness is applied to the tail, and the rat's hindquarters are elevated by attaching the harness to a pulley system. Weight-bearing hind limbs are unloaded, and there is a headward fluid shift. The tail-suspended rats are able to move freely about their cages on their forelimbs and tolerate this procedure with minimal signs of stress. The cage used in Holton's model is basically a clear acrylic box set on a plastic grid floor with the pulley and tail harness system attached to the open top of the cage. Food is available from a square food cup recessed into a corner of the floor. In this system, urine, feces, and spilled food fall through the grid floor onto absorbent paper beneath the cage and cannot be separated and recovered quantitatively for analysis in metabolic balance studies. Commercially available metabolic cages are generally cylindrical and have been used with a centrally located suspension apparatus in other space flight models. The large living area, three times as large as most metabolic cages, and the free range of motion unique to Holton's model, essential for musculoskeletal investigations, were sacrificed. Holton's cages can accommodate animals ranging in weight from 70 to 600 g. Although an alternative construction of Holton's cage has been reported, it does not permit collection of separate urine and fecal samples. We describe the modifications to Holton's food delivery system, cage base, and the addition of a separator system for the collection of urine and fecal samples for metabolic and nutrition studies in the tail suspension model.

Harper, Jennifer S.↗
NASA NTRS2003

The Effect of Spaceflight on the Ultrastructure of the Cerebellum

In weightlessness, astronauts and cosmonauts may experience postural illusions as well as motion sickness symptoms known as the space adaptation syndrome. Upon return to Earth, they have irregularities in posture and balance. The adaptation to microgravity and subsequent re-adaptation to Earth occurs over several days. At the cellular level, a process called neuronal plasticity may mediate this adaptation. The term plasticity refers to the flexibility and modifiability in the architecture and functions of the nervous system. In fact, plastic changes are thought to underlie not just behavioral adaptation, but also the more generalized phenomena of learning and memory. The goal of this experiment was to identify some of the structural alterations that occur in the rat brain during the sensory and motor adaptation to microgravity. One brain region where plasticity has been studied extensively is the cerebellar cortex-a structure thought to be critical for motor control, coordination, the timing of movements, and, most relevant to the present experiment, motor learning. Also, there are direct as well as indirect connections between projections from the gravity-sensing otolith organs and several subregions of the cerebellum. We tested the hypothesis that alterations in the ultrastructural (the structure within the cell) architecture of rat cerebellar cortex occur during the early period of adaptation to microgravity, as the cerebellum adapts to the absence of the usual gravitational inputs. The results show ultrastructural evidence for neuronal plasticity in the central nervous system of adult rats after 24 hours of spaceflight. Qualitative studies conducted on tissue from the cerebellar cortex (specifically, the nodulus of the cerebellum) indicate that ultrastructural signs of plasticity are present in the cerebellar zones that receive input from the gravity-sensing organs in the inner ear (the otoliths). These changes are not observed in this region in cagematched ground control animals. The specific changes include the formation of lamellar bodies, profoundly enlarged Purkinje cell mitochondria, the presence of inter-neuronal cellular protrusions in the molecular layer, and signs of degeneration in the distal dendrites of the Purkinje cells. Since these morphologic signs are not apparent in the control animals, they are not likely to be due to caging or tissue processing effects. The particular nature of the structural alterations in the nodulus, most notably the formation of lamellar bodies and the presence of degeneration, further suggests that excitotoxicity (damaging overstimulation of neurons) may play a role in the short-term neural response to spaceflight. These findings suggest a structural basis for the neuronal and synaptic plasticity accompanying the central nervous system response to altered gravity and help identify the cellular bases underlying the vestibular abnormalities experienced by astronauts during periods of adaptation and re-adaptation to different gravitational forces. Also, since the short- and long-term changes in neural structure occurring during such periods of adaptation resemble the neuronal alterations that occur in some neurologic disorders such as stroke, these findings may offer guidance in the development of strategies for rehabilitation and treatment of such disorders.

Holstein, Gay R.↗