Biomedical subjects

B D Ulrich

Publications and source records attributed to B D Ulrich.

10 recordsLinked to original sources

PubMed2001

The Feldenkrais Method: a dynamic approach to changing motor behavior.

This tutorial describes the Feldenkrais Method and points to parallels with a dynamic systems theory (DST) approach to motor behavior Feldenkrais is an educational system designed to use movement and perception to foster individualized improvement in function. Moshe Feldenkrais, its originator, believed his method enhanced people's ability to discover flexible and adaptable behavior and that behaviors are self-organized. Similarly, DST explains that a human-environment system is continually adapting to changing conditions and assembling behaviors accordingly. Despite little research, Feldenkrais is being used with people of widely ranging ages and abilities in varied settings. We propose that DSTprovides an integrated foundation for research on the Feldenkrais Method, suggest research questions, and encourage researchers to test the fundamental tenets of Feldenkrais.

Activities of Daily Living↗

PubMed2001

Treadmill training of infants with Down syndrome: evidence-based developmental outcomes.

OBJECTIVE: On average, infants with Down syndrome (DS) learn to walk about 1 year later than nondisabled (ND) infants. The purpose of this study was to determine if practice stepping on a motorized treadmill could help reduce the delay in walking onset normally experienced by these infants. METHODS: Thirty families of infants with DS were randomly assigned to the intervention or control group. All infants were karyotyped trisomy 21 and began participation in the study when they could sit alone for 30 seconds (Bayley Scales of Infant Development, Second Edition 1993, item 34). Infants received traditional physical therapy at least every other week. In addition, intervention infants received practice stepping on a small, motorized treadmill, 5 days per week, for 8 minutes a day, in their own homes. Parents were trained to support their infants on these specially engineered miniature treadmills. Every 2 weeks research staff went into the homes and tested infants' overall motor progress by administering the Bayley Scales of Infant Development, Second Edition, monitored growth status via a battery of 11 anthropometric measures, and checked parents' compliance with physical therapy and treadmill intervention. The primary measures of the intervention's effectiveness were comparisons between the groups on the length of time elapsed between sitting for 30 seconds (entry into the study) and 1) raising self to stand; 2) walking with help; and 3) walking independently. RESULTS: The experimental group learned to walk with help and to walk independently significantly faster (73.8 days and 101 days, respectively) than the control group, both of which also produced large effect size statistics for the group differences. The groups were not statistically different for rate of learning to raise self to stand but there was a moderate effect size statistic suggesting that the groups were meaningfully different in favor of the experimental group. CONCLUSIONS: These results provide evidence that, with training and support, parents can use these treadmills in their homes to help their infants with DS learn to walk earlier than they normally would. Current research is aimed at 1) improving the protocol to maximize outcome; 2) determining the impact of treadmill practice on walking gait patterns; 3) testing the application to other populations with a history of delays in walking; and 4) determining the long-term benefits that may accrue from this form of activity. motor development, Down syndrome, early intervention, walking.

Age Factors↗

PubMed1997

Sensitivity of infants with and without Down syndrome to intrinsic dynamics.

We examined the way in which infants with and without Down syndrome (DS) adapted their intrinsic dynamics, that is, their spontaneous leg movements, to perturbations. Weights totaling 25%, 50%, and 100% of their estimated calf mass were attached to one leg as they sat in an infant seat and moved freely. Particularly at higher weightings, infants in both groups demonstrated bilateral sensitivity and adaptability by increasing activity levels of the unweighted leg relative to the weighted leg. Individual differences in sensitivity thresholds were observed for both groups, but more infants with than without DS demonstrated minimal overt adaptation to the perturbation. We argue that the capacity to respond differentially to the dynamics of movement contexts is necessary for acquiring functional motor skills.

Down Syndrome↗

PubMed1995

Developmental shifts in the ability of infants with Down syndrome to produce treadmill steps.

BACKGROUND AND PURPOSE: In this study, we used a dynamic systems strategy to examine longitudinally the ability of infants with Down syndrome to produce alternating steps when supported on a motorized treadmill. SUBJECTS: Seven infants participated, ranging in age from 8 to 11 months at entry into the study and 13 to 29 months at their final session. METHODS: Data were collected in the infants' homes on a monthly basis. Testing continued until each subject produced consistent alternating step patterns during three consecutive test sessions. RESULTS: All infants responded by producing alternating steps, on average, 13.3 months before they walked independently, but they initiated this response at a wide range of chronological ages and significantly later than reported previously for nondisabled infants. Similar developmental variables (control parameters) marked the shift into responsiveness to the treadmill context for all infants with Down syndrome, but these variables differed from those identified for nondisabled infants. CONCLUSION AND DISCUSSION: With age, alternating treadmill stepping became a more stable response, although the relative timing of interlimb coordination (phase lag) of the step cycles remained quite variable across ages. We discuss our results relative to the usefulness of dynamic systems theory in understanding delayed development and the possibilities of pursuing the treadmill paradigm as an intervention approach.

Down Syndrome↗

PubMed1995

Spontaneous leg movements of infants with Down syndrome and nondisabled infants.

Infants with Down syndrome (DS) represent a population in which new behaviors are acquired significantly more slowly than in nondisabled infants. We propose that infants' spontaneous movements hold a key to understanding the process of development--of integrating intrinsic dynamics and function. In this investigation, we compared the spontaneous leg movements of 10 infants with DS and 2 groups of nondisabled (ND) infants matched for chronological age and motor age. In contrast to common perceptions, we did not observe a significant difference in the frequency of movements between infants with DS and ND infants. But, infants with DS demonstrated significantly fewer of the most complex patterned leg movements, that is, kicking patterns. Further, the frequency with which both DS and ND infants kicked was significantly correlated with the age at which they began to walk. Biomechanical variables were identified, as well, that related to their emergent movement patterns. These data are consistent with Edelman's proposal that spontaneous movements that occur repeatedly in regions of the organism's functional work space facilitate the development of stable behavioral patterns and emphasize the role of the interaction of multiple subsystems in the emergence of new behaviors.

Arousal↗

PubMed1992

Alternating stepping patterns: hidden abilities of 11-month-old infants with Down syndrome.

Normally developing infants can produce organized alternating stepping patterns long before they stand alone or attempt to walk, if supported upright on a motorized treadmill. The purpose of this study was to examine whether infants with Down syndrome, who begin to walk at a much later age than non-disabled infants, could produced alternating steps in a similar way. Six of the seven 11-month-old infants studied responded to the treadmill stimulus by producing alternating steps. This suggests that the basic neural substrate necessary for upright locomotion is available long before walking occurs in infants with Down syndrome, as it is in normally developing infants. The infants in this study began to walk at an average of 13.3 months after demonstrating the ability to produce treadmill steps.

Down Syndrome↗

PubMed1991

Hidden skills: a dynamic systems analysis of treadmill stepping during the first year.

When prelocomotor infants are supported on a motorized treadmill, they perform well-coordinated, alternating stepping movements that are kinematically similar to upright bipedal locomotion. This behavior appeared to be a component of independent walking that could not be recognized without the facilitating context of the treadmill. To understand the ontogenetic origins of treadmill stepping and its relation to later locomotion, we conducted a longitudinal study using an experimental strategy explicitly derived from dynamic systems theory. Dynamic systems theory postulates that new forms in behavior emerge from the cooperative interactions of multiple components within a task context. This approach focuses on the transitions, often nonlinear, where one preferred mode of behavior is replaced by a new form. Specific predictions about these transitions help uncover the processes by which development proceeds. Chapters II, III, and IV introduce dynamic principles of pattern formation and their application to development. In our application of these principles, we tested nine normal infants twice each month beginning from month 1 in a task where the treadmill speed was gradually scaled up and in an additional condition where each leg was driven by the treadmill at a different speed. Kinematic variables were derived from computerized movement analysis equipment and videotaped records. We also collected a number of anthropometric measurements, Bayley motor scores, and a behavioral mood scale for each month. Several infants stepped on the treadmill in their first month, but in all infants performance showed a rapidly rising slope from month 3 to month 6. Infants also showed corresponding improvement in adjustments to speed and relative coordination between the legs. In dynamic terminology, we found evidence that alternating stepping on the treadmill became an increasingly stable attractor during the middle months of the first year. Dynamic predictions that transitions would be characterized by increased variability and sensitivity to perturbation were borne out. Identifying the transitions enabled us to suggest a control parameter or variable moving the system into the stable response to the treadmill. This appeared to be the waning of flexor dominance in the legs during posture and movement that allowed the leg to be stretched back on the treadmill and so elicited the bilaterally alternating response. Further studies are needed to test this hypothesis. This dynamic analysis confirmed earlier suggestions that skill in general, and locomotion in particular, develops from the confluence of many participating elements and showed how emergent forms may result from changes in nonspecific components. A dynamic approach may be useful for understanding ontogenetic processes in other domains as well.

Exercise Test↗

PubMed1990

Understanding movement control in infants through the analysis of limb intersegmental dynamics.

One important component in the understanding of the control of limb movements is the way in which the central nervous system accounts for joint forces and torques that may be generated not only by muscle actions but by gravity and by passive reactions related to the movements of limb segments. In this study, we asked how the neuromotor system of young infants controls a range of active and passive forces to produce a stereotypic, nonintentional movement. We specifically analyzed limb intersegmental dynamics in spontaneous, cyclic leg movements (kicking) of varying intensity in supine 3-month-old human infants. Using inverse dynamics, we calculated the contributions of active (muscular) and passive (motion-dependent and gravitational) torque components at the hip, knee, and ankle joints from three-dimensional limb kinematics. To calculate joint torques, accurate estimates were needed of the limb's anthropometric parameters, which we determined using a model of the human body. Our analysis of limb intersegmental dynamics explicitly quantified the complex interplay of active and passive forces producing the simple, involuntary kicking movements commonly seen in 3-month-old infants. our results revealed that in nonvigorous kicks, hip joint reversal was the result of an extensor torque due to gravity, opposed by the combined flexor effect of the muscle torque and the total motion-dependent torque. The total motion-dependent torque increased as a hip flexor torque in more vigorous kicks; an extensor muscle torque was necessary to counteract the flexor influences of the total motion-dependent torque and, in the case of large ranges of motion, a flexor gravity torque as well. Thus, with changing passive torque influences due to motions of the linked segments, the muscle torques were adjusted to produce a net torque to reverse the kicking motion. As a consequence, despite considerable heterogeneity in the intensity, range of motion, coordination, and movement context of each kick, smooth trajectories resulted from the muscle torque, counteracting and complementing not only gravity but also the motion-dependent torques generated by movement of the linked segments.

Journal Article↗

PubMed1989

Development of stepping patterns in human infants: a dynamical systems perspective.

Upright locomotion has been, perhaps, the most studied of all human motor behaviors. The acquisition of this motor milestone has been of major interest to developmentalists from the motor as well as the cognitive domains. Until recently, developmentalists have chosen a nonexperimental approach, opting instead to describe the motor behaviors that precede walking, assigning them precursor status, and attributing the sequence solely to maturation of the nervous system. In this paper, I will discuss evidence that suggests that we may better understand this and other aspects of motor development by viewing them from the theoretical perspective of nonlinear and complex dynamical systems. Focus will be on the availability of a coordinated and alternating stepping pattern throughout much of the first year of life. Factors that influence the expression of and variability in this movement pattern will also be discussed. In addition, I will address the need to understand the development of control of pattern formations as well as their coordination, and I will discuss one approach that may provide some insight; that is, to study the modulations and patterns of muscle and other forces underlying limb movements.

Journal Article↗

PubMed1987

Bilateral coordination in human infants: stepping on a split-belt treadmill.

A motorized treadmill often elicits locomotor-like alternate stepping in 7-month-old infants who normally perform few, if any, stepping movements. The step cycle duration is a function of the speed of the treadmill. When infants were held so that each leg was on a separate treadmill belt, each of which was driven at a different speed, the overall cycle duration was intermediate between the cycle durations at the fast or slow speeds alone. Infants shortened the stance on the slow belt and increased the stance on the fast belt to maintain regularly alternating steps. Even before voluntary locomotion, both legs acted in a cooperative manner, with the dynamic status of one limb affecting the timespace behavior of the opposite limb.

Female↗