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fNIRS Brain Imaging: Development of Functional Motor Control

Investigators: Ryota Nishiyori, Silvia Bisconti, Beverly Ulrich.

The purpose of this study is to use a new technology, functional near-infrared spectroscopy (fNIRS) to study the emergence of cortical involvement in the control of functional motor tasks. Specifically, we are interested in the development of reaching and stepping. We use fNIRS to examine the differences in amount and symmetry of activation of the primary motor cortex (M1) and frontal areas during the execution of these motor tasks.

To enable us to understand the emergence reaching and stepping we will investigate if the amount and symmetry of activation of the arm regions for reaching, and leg regions for stepping will change between the ages of 6 months (low but functional skill level) and 12 months (highly skilled). As this technology is new, we begin by verifying with adults that we are able to 1) map the specific locations of upper and lower limb activity and 2) observe difference between one and two limbs moving in M1. In collaboration with the Pediatric Multimodal Imaging group at the Center for Human Growth and Development (CHGD) at the University of Michigan, we are using a 32-Channel TechEn CW6 system.

Treadmill Training for Infants Born with Spina Bifida

Investigators: Do Kyeong Lee, Ryota Nishiyori, Arielle Bianco, and Beverly Ulrich.

In this study we build on the results of several basic science studies we published previously involving infants born with myelomeningocele (MMC) the most common form of spina bifida . We are assessing the impact of functionally specific, rigorous, and long-term activity, early in life, on the development of their bone mineral content, bone growth, development of muscle control, spinal reflexes, and the ability to step. MMC is a neural tube defect in which one or more of the vertebral arches fails to close allowing the spinal cord to protrude from the spine, causing sensory and motor damage. Although these infants receive neurosurgery to replace the spine within the vertebral column and protect it, usually within 24 hours of birth, this does not “fix” the neurological damage. Typically, these infants have difficulty learning to control the legs and walk.

We provide families with small motorized treadmills, in their homes. They support their babies upright on it to help them practice supporting their weight upright and stepping (10 minutes per day, 5 days per week). Families enroll for one year and infants receive traditional physical therapy as well. We conduct extensive testing at three times, a.) prior to onset the treadmill practice, b.) after six months, and c.) after twelve months. We work with families every two weeks to support their efforts and to conduct additional assessments. Currently our work is being funded by the Blue Cross Blue Shield of Michigan Foundation.

Analyzing the Development of Locomotor Activity in Infants with Myelomeningocele

Investigators: Caroline Teulier, Beth A Smith, Masayoshi Kubo, Chia-Lin Chang, Victoria Moerchen, Karin Muraszko, and Beverly D Ulrich.

The purpose of this study is to describe and analyze the development of leg control in infants born with Myelomeningocele (MMC) and with typical development (TD). We are focusing on the quality (control and coordination) and quantity of infants’ stepping movements over the first postnatal year.

We studied 12 infants in each group (MMC and TD), longitudinally, at ages 1, 3, 6, 9, 12, 18 months, at the onset of walking and after 3 months of walking experience. All infants with MMC have a myelomeningocele located at a sacral or lumbar level. Infants with TD were without known cognitive, sensory or motor impairments. We supported them on a table top in 4 attempts to elicit newborn stepping response, and on a small motorized treadmill for 10 trials of 20s. Subsequently we monitored their supine spontaneous leg movements for 5 minutes. Reflective markers were placed bilaterally on leg joints; data were captured using a 6-camera Peak Motus™ system. EMG electrodes were placed on gastrocnemius, tibialis anterior, quadriceps and hamstring muscles. Results will help us understand the impact of internal (spinal cord lesions) and external (environmental) factors on motor skill acquisition in humans, and also help us to design therapeutic interventions that facilitate the acquisition of walking and lower limb control in infants with MMC.

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Effect of Enhancing Sensory Input on Motor Output in Infants with Myelomeningocele (MMC)

Investigators: Caroline Teulier, Beth A Smith, Jill Heathcock, Victoria Moerchen, Karin Muraszko, and Beverly D Ulrich.

With this set of three studies we want to determine the effect of enhancing the sensory input available on the activation of the neuromotor system, monitored kinematically and kinetically. We are addressing the potential change in responsiveness related to age, to different forms of sensory information (visual, tactile, load), and to combinations of enhanced sensory input that may be needed to surpass their threshold of sensitivity to sensory information.

In Study One we are testing the impact of enhancing one single source of sensory input at a time. We are testing 12 babies in each of two age groups, 2-5 and 7-10 months, all with lesions within the lumbar or sacral areas. We support them upright on a small motorized treadmill, use motion capture and EMG to monitor steps, non-stepping leg motion, and muscle activation patterns under the following treadmill conditions: baseline trials (typical smooth belt), visual flow enhancement (belt covered in a checkerboard design), enhanced tactile pressure on the sole (weight added to legs), enhanced joint input (babies positioned near the rear edge of the belt to limit stance duration causing ankle and hip to extend rapidly as foot “drops off” the edge quickly), enhanced stance (Velcro socks on a belt covered with fabric increases foot contact in stance), enhanced friction (Dycem covered belt increases coefficient of friction).

In Study Two we combine pairs of stimuli tested in Study One to determine if their combination will be more effective than one alone. The age groups remain the same but sample size is 6 per age group. Conditions are: baseline, enhanced visual flow plus friction, visual flow plus enhanced joint input, friction plus enhanced joint input, enhanced joint input plus enhanced tactile pressure on the sole.

In Study Three we use manual manipulation of the legs in varying combinations, interspersed with baseline trials, to determine if this increased (primes) muscle activity and leads, subsequently, to increased voluntary step production.

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Integrity of Neuromotor Repsonses in Infants with Myelomeningicele

Investigators: Caroline Teulier, Beth A Smith, Genna Mulvey, Bernard Martin, Karin Muraszko, and Beverly D Ulrich

Our aim with these studies is to use neurophysiologic techniques, vibration and tendon-tap stimulation, to assess the mono- and polysynaptic sensorimotor loops of gait muscles of infants with myelomeningocele (MMC). We will also test the effect of vibratory stimulation to the soles of the feet and leg muscles on the occurrence and quality of alternating stepping patterns.

Study 1: We are evaluating the function of monosynaptic, polysynaptic, and pre-synaptic Ia-proprioceptive loops for three core locomotor muscles in each leg. We will test the tendon response (T-reflex) in the tibialis anterior, gastrocnemius and quadriceps muscles of infants with and without MMC. We will use continuous vibration to test inhibition of the T-reflex, the Tonic Vibration Reflex (TVR) and the Antagonist Vibration Reflex (AVR) in the same muscles. Infants will be seated securely in an adjustable infant chair. We will encourage them to remain calm and will apply tendon-tap, tendon-tap and vibration or vibration only to each tendon when the infant is not actively contracting the muscle. Using a Noraxon EMG system and computer we will record muscle responses of stimulated muscles (and antagonist muscle when attempting to elicit an AVR), vibration signal, magnitude and timing of mechanical events. The EMG of the hamstrings will be recorded when testing the quadriceps muscle.

Study 2: We are determining the impact of vibration applied to the sole of the foot or to the leg muscles on stepping movements. We will test stepping in response to vibratory input at the muscle belly or on the soles of the feet while we support infants with and without MMC upright on a stationary surface and upright in a partial body-weight supported treadmill context. We will provide alternating vibration to 1) the soles of the feet, 2) to the muscle bellies of the quadriceps muscles, or 3) to the muscle bellies of the gastrocnemius muscles. We will use digital video to record stepping responses.

Participants: 12 infants with MMC (sacral or lumbar lesion levels) and 12 infants with TD, ages 2-5 months or 7-10 months.

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Effects of Environmental Perturbations on Variability and Stability of Gait Patterns in Older Adults with Down Syndrome

Investigators: Beth A. Smith and Beverly D. Ulrich.

The combined effects of ligamentous laxity, low tone, obesity, inactivity and physiological decrements associated with aging lead to stability-enhancing adaptations during unperturbed, comfortable walking at a younger chronological age in adults with Down syndrome (DS) as compared to their peers with typical development (TD) (Smith and Ulrich, 2008). To extend our understanding of gait adaptation and stability in older adults with DS, we are using 3-D motion analysis and a safety harness to assess gait variability and falls during challenging and commonly encountered environmental perturbation conditions. At the conclusion of this study we will identify some of the environmental perception-action scenarios that present the most challenge to walking stability in adults with DS, information we believe can affect intervention practices.

Participants: 14 adults with DS, 35 to 65 years of age, and 14 age, height and weight-matched adults with TD. As of June, 2008, we are recruiting only adults with DS.

Walking conditions: unperturbed, counting (divided attention), distracting sounds, uneven surface, obstacle, low light condition, a combination of counting and low light, and a combination of uneven surface and distracting sounds.

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Production of Stiffness and Impulse during Treadmill Walking in Older Adults with Down Syndrome (DS)

Investigators: Beth A. Smith, Masa Kubo, Ken Holt, Elliott Saltzman, Beverly D. Ulrich.

We are using an escapement-driven damped inverted pendulum and spring model to ]estimate global stiffness and impulse values. Stiffness represents a conservation mechanism of soft tissue, the storage and return of elastic energy of muscles and tendons. Angular impulse is energy released into the system by the muscles to replace what is lost during each walking stride. This study advances our work investigating stiffness and impulse values during walking in toddlers and preadolescents with DS, now investigating the combined effects of DS and the neurophysiologic changes associated with aging on the production of stiffness and impulse during walking.

Participants: 12 older adults with DS and 12 adults with typical development were matched for height, weight and age (range 35 to 62 years). We used a 6-camera motion capture system to record 3-dimensional full body joint marker locations as participants walked across the room at a comfortable self-selected overground walking pace and on a treadmill at 40%, 75% and 110% of their overground speed.

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Walking Strategies and Variability in New Walkers with and Without Down Syndrome

Investigators: Beth A. Smith, Genna Mulvey, Beverly Ulrich, Nick Stergiou, Masayoshi Kubo, Chia-Lin Chang.

At the onset of walking, toddlers produce a wide variety of step lengths and widths. Patterns within this variability, as well as how they adjust their walking patterns to external constraints such as obstacles, can tell us about the function this variability serves as they explore their newfound skills. Toddlers with typical development and toddlers with Down syndrome walked on an instrumented gait mat and on a treadmill across months of walking experience. We analyzed the nonlinear patterns of variability in their knee position across consecutive strides using the Lyapunov Exponent values and surrogation analysis. In addition, we placed an obstacle across their walking path and observed the strategies they used to cross the obstacle, along with their gait characteristics as they approached the obstacle. Through this study, we gain a greater understanding of the development of stable walking patterns as well as strategies used to cope with challenges to walking stability.

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Effects of constraints (clothing and motion-capture devices) on treadmill steps in infants

Investigators: Anniek Groenen, Anne Kruijsen, Genna Mulvey, Beverly Ulrich.

Analysis across studies conducted in this lab has suggested that the clothing and measurement equipment babies have worn while stepping on a treadmill may reduce their leg movements compared to when they wear nothing. To examine this, we supported infants with typical development on a treadmill to observe differences in the stepping movements they made under four different conditions: 1) Wearing nothing 2) Wearing a cloth swim diaper only 3) Wearing a disposable diaper only 4) Wearing a disposable diaper, tights, muscle sensors (EMG), and reflective markers on their legs. The long-term goal is to use the information from this proposed study as the basis for developing the protocols for treadmill therapy to assist infants with myelomeningiocele in learning to walk: It is important to determine what the child should wear during therapy to provide the best conditions for eliciting stepping movements while minimizing cleaning burdens on parents during at-home therapy sessions.

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Your Kinesiology Connection

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