RIC Research Seminars 2016 - Rehabilitation Institute of Chicago

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RIC Research Seminars 2016

To schedule a seminar at SMPP, please contact the seminar coordinators at seminar-coordinator@ricres.org

  ***All seminars are in RIC, Room 1301 (map) at 12pm - 1pm unless otherwise noted.

Fri, Dec 09

Speaker: Jacob Sosnoff , PhD

Title: Cognitive-Motor Interference in Multiple Sclerosis: Assessment, Predictors and Prevention
Abstract:Multiple sclerosis is a leading cause of neurological disability in young adults. It is estimated that there are nearly 400,000 individuals in US living with MS and over 2.5 million worldwide. Individuals with multiple sclerosis (MS) regularly exhibit deficits in motor and cognitive function. Recent evidence suggests that these impairments are compounded when motor and cognitive task are performed simultaneously such as walking while talking. The changes incurred during simultaneous performance of motor and cognitive tasks are a result of cognitive-motor interference (CMI). Recently, research has been conducted to understand and analyze the impact of CMI. This presentation will review evidence, correlates, and consequences of CMI in MS. Novel data on the effect of rehabilitation strategies on cognitive motor interference in persons with multiple sclerosis will also be presented. Lastly, knowledge gaps pertaining to CMI in MS will be identified.

Fri, Dec 02

Speaker: Carolynn Patten, PhD, PT, FAPTA

Title: Upper-extremity Rehabilitation Post-stroke: are we asking the right questions?
Abstract: Stroke is the leading cause of disability worldwide with the most persistent stroke-related motor impairments affecting the upper-extremity (UE)1 . While this problem is well recognized, effective approaches for rehabilitation of UE hemiparesis remain elusive. Of note, the majority of stroke rehabilitation therapies target means to facilitate the involved hemisphere in an effort to induce experience-dependent neural plasticity. However, inhibitory circuits are also critical to motor control and have not been well studied following stroke.
Short intracortical inhibition (SICI) is a GABAa-mediated phenomenon argued to mediate motor selectivity and contribute to performance of dexterous tasks. Here we studied SICI at rest and during active hand movements. When measured at rest, we found SICI magnitude was similar across healthy controls, affected and unaffected hemispheres of persons post-stroke. However, when measured during activity SICI is markedly reduced in the affected hemisphere of persons with chronic stroke and the magnitude of SICI measured during activity was strongly associated with motor performance (B&B test scores).
It has been argued that reduced GABAa inhibition may enable neural plasticity in the early period following stroke. However, persistent disinhibition is maladaptive. The magnitude of SICI disinhibition during activity could serve as a biomarker for motor recovery. Our results also suggest that repetitive limb use in individuals revealing GABAa dysfunction may exacerbate a maladaptive state and interfere with motor recovery. Relevant to contemporary stroke rehabilitation, these findings contribute to ongoing discussion regarding strategies to optimize recovery

Wed, Nov 30

Speaker: Jui-Te (Ray) Lin, PhD

Title: The influence of wheelchair mechanical parameters and human physical fitness on propulsion effort
Abstract: The majority of wheelchair studies that evaluate propulsion efforts across wheelchair configurations examines long and steady propulsion. However, the results of these studies cannot represent performance during daily maneuvers, which include changes in speed and direction. Although each component of wheelchair configuration was widely examined, these studies were not able to describe the mechanical properties of wheelchairs in a systematic way. Beyond mechanical properties, physical fitness was proved to be related to health status and exercise performance. In addition, the biomechanical characteristics of the user were shown to influence wheelchair maneuvers. However, it is still unknown how these human factors influence wheelchair propulsions altogether. Therefore, the overall objective of my study is to define the relative influence of mechanical wheelchair parameters as well as individual physical and biomechanical variables on propulsion efforts during over-ground maneuvers.
In this study, we developed and validated a test that quantifies the impact of wheelchair configurations on frictional energy loss, particularly loss related to turning trajectories. We also developed a testing protocol designed to measure users’ maximum propulsion strength and aerobic capacity. After methods development, we identified the impact of the mechanical parameters of wheelchairs as well as the physical and biomechanical variables of operators on propulsion efforts during over-ground maneuvers. Mechanical parameters include both inertial and frictional measurements. Operator factors include shoulder position, propulsion strength, and aerobic capacity. To evaluate the performance of daily maneuvering, we designed a repeatable maneuver consisting of several momentum changes.
Because of the breadth of wheelchair configurations and variance in user physical capacity, it is necessary to define the effects of wheelchair configurations and user fitness on propulsion with a systematic approach. The study results demonstrated that shoulder position and weight distribution had a significant influence on frictional energy loss and propulsion efforts. However, aerobic capacity and muscle strength had less influence on daily wheelchair maneuvers. Clinicians can use our findings to improve wheelchair customizations and to prescribe human fitness programs. Manufacturers can also use our findings to improve their wheelchair design by understanding the importance of shoulder position and weight distribution.

Fri, Nov 18

Speaker: Kevin Mattheus Moerman, PhD

Title: Non-invasive analysis of soft tissue mechanical properties
Abstract: Understanding the mechanical properties of living human soft tissue is relevant to many areas of research, including impact biomechanics, rehabilitation engineering, tissue engineering, and surgical simulation. Constitutive property analysis of living human tissue presents with significant challenges and requires non-invasive methods, such as: non-invasive mechanical tissue excitation and inverse analysis of detailed non-invasively measured experimental boundary conditions. This presentation will feature an overview of non-invasive methods for the determination of soft tissue mechanical properties. Finally the use of such biomechanical data for patient-specific medical device design will also be discussed.

Wed, Nov 2

Speaker: Geoff Fernie, PhD, PEng, CEng, FCAHS ​

Title: Research at Toronto Rehabilitation Institute
Bio: Geoff Fernie, PhD, PEng, CEng, FCAHS is the Institute Director, Research, at Toronto Rehabilitation Institute-University Health Network. He has a primary appointment at the University of Toronto as Professor in the Department of Surgery with cross appointments that include the Institute of Biomaterials and Biomedical Engineering, Department of Mechanical and Industrial Engineering, Department of Physical Therapy and Department of Occupational Science and Occupational Therapy.
Dr. Fernie has led the creation of the most advanced product development and testing environment in rehabilitation technology in the world. He has a track record of taking inventions from the laboratory and making them available on the market. He currently has 8 commercialized products and 4 currently in clinical trials, and has helped to launch several companies. In addition to his investigative work as a world class scientist, and an outstanding and progressive engineer, Dr. Fernie has served on numerous committees to inform and advance public policy pertaining to persons with disabilities; he has chaired a number of influential conferences to further advance the profile and the need to address issues related to disability and aging. Dr. Fernie has over 140 peer-reviewed journal papers and book chapters, 22 awarded patents and an additional 13 patent filings.
Dr. Fernie has received several awards for his achievements in improving the lives of people with disabilities and exemplary dedication to the creation and design of modern technology, most recently the Queen Elizabeth II Diamond Jubilee Medal in 2012, the Inaugural 2014 Honourable David C. Onley Award and the Canadian Society for Biomechanics Biannual Career Award in 2014.

Fri, Sep 20

Speaker: Emily Lawrence, PhD

Title: Demographic and Clinical Covariates of Sensorimotor Processing
Abstract: ​Dexterity can be defined as using the upper or lower extremities to stabilize unstable objects at sub-maximal force levels. The Strength–Dexterity (SD) paradigm asks participants to compress slender and compliant springs prone to buckling at low forces (i.e., <3N with the fingers and <15% of the body weight with the isolated leg). The maximal level of steady state SD compression (i.e., mean compression force) has been successfully used to quantify the effects of age and sex on neural control capabilities during a dynamic manipulation task. However, as one would expect, sustained compression of deformable and unstable objects exhibits nonlinear, time-varying forces, which may provide additional insight on the neural control of dynamical regulation of low forces. While traditional linear analyses (i.e., root mean square, standard deviation, etc.) have shown limited success, they lack the robustness of a nonlinear analytic approach. Therefore, this presentation highlights research employing the delayed embedding theorem to reconstruct phase portraits from SD paradigm compression force data to explore the demographic and clinical covariates of sensorimotor processing for both finger and leg dexterity.

Fri, Sep 16

Speaker: Cristina Bayón Calderón

Title: Research Lines of group of Neural and Cognitive Engineering: Novel Robotic Platform for Gait Rehabilitation and Training in Children with Cerebral Palsy

Abstract:   In the last decades, different technologies have emerged with the aim of helping the work of the medicine. The group of Neural and Cognitive Engineering (gNEC-CSIC-Spain) has a long track expertise in research studies that generate new technological solutions pursuing the comprehension and control of human biological systems and its relation to the environment. Research activities aim at leading the transition from classic robots to neuroprostheses in the field of rehabilitation robotics.

The talk will present a new robotic device for gait rehabilitation in children with Cerebral Palsy and similar motor disorders: CPWalker. The over ground prototype allows tailored therapies with body weight and autonomous locomotion support, and provides means for testing novel rehabilitation strategies depending on the patients' needs. Preliminary results of a pilot study with pediatric population will be shown.

Fri, Sep 09

Speaker: Allison S. Hyngstrom, P.T., PhD

Title: Neuromuscular Fatigue and Motor Unit Firing Behavior Post Stroke

Abstract: An often overlooked aspect of force generation in the chronic stroke population is neuromuscular fatigue. Neuromuscular fatigue is an acute, exercise-related reduction in force or power and it impacts a person’s functional endurance. For example, neuromuscular fatigue can limit the distance a stroke survivor can walk at a grocery store without rest or the ability to maintain a fast enough walking speed to cross the street safely. In healthy individuals, both neural and muscular factors contribute to neuromuscular fatigue, but muscular mechanisms (e.g. build-up of metabolic byproducts) play a primary role in limiting performance. In contrast, data from our laboratory and others, suggest that impaired neural excitation of the paretic muscles primarily contributes to neuromuscular fatigue. Limited neural excitation of paretic muscle not only interferes with the acute force demands of an activity, but also limits strength training, which depends on sufficient muscle activation to initiate muscular hypertrophy. In our laboratory, we use high density surface EMG arrays to understand how stroke-related changes in motor unit firing behavior may contribute to neuromuscular fatigue. Our initial results indicate that post stroke there is a decreased ability to modulate motor unit firing rates as fatigue develops and this may contribute to limitations in muscle contraction endurance.

Fri, Aug 19

Speaker: Andrea A. Domenighetti, PhD

Title: An Introduction To Molecular Biology Of The Cell

Abstract:This talk is addressed to researchers and non-researchers alike that have little or no knowledge - but would like to know more - about cellular biology and mechanisms of gene expression. During this presentation I will give an introduction to the cell and its genome (diversity of cells and genomes; genetic information in Eucaryotes), as well as basic information on mechanisms of gene expression (definitions of DNA, chromatin and chromosome; how cells read the genetic information from DNA to protein; mechanisms of gene expression to create specialized cell types from a stem cell; examples of pathologies associated or driven by a change in gene expression).

Fri, Aug 12

Speaker: Junho Choi, PhD

Title: Robots for rehabilitation and assistance in KIST
Abstract:This talk introduces rehabilitation robots developed in Korea Institute of Science and Technology. COWALK, which is a treadmill-based gait training system, is developed to help patients with difficulties in maintaining normal gait pattern to regain normal gait pattern. In order to provide more natural gait pattern, COWALK is equipped with actuators to provide pelvic motions. With pelvic motion, it is possible for the patient to improve their balance during walking. Intention of the patients, which is interpreted as acceleration or deceleration, is estimated using interaction force and/or electromyography sensors to keep the patients motivated. COWALK-Mobile, which is an exoskeleton to assist patients with activities of daily living’s, is developed based on biomechanics of walking. Using dynamics of walking, it is possible to reduce required motor torque, which results in further reduction of weight of the exoskeleton. Mechanically adjustable stiffness actuator(MASA) is series elastic actuator with variable elasticity. Using MASA, a robotic device for elbow training is developed. According to performance of the patient, stiffness of the MASA is controlled to increase interaction torque of the patients.

Fri, Aug 05

Speaker: Kevin Young, PhD

Title: Minimally Invasive Principles and Technology to Measure Dynamic Skeletal Muscle Sarcomere Length
Abstract:Millions of patients in the United States suffer every year from movement disorders and weakness. Unfortunately, the gold standard to diagnose these problems is the muscle biopsy, which requires painful surgeries and is often difficult to obtain.To overcome this challenge, we are developing a new method called resonant reflection spectroscopy to collect sarcomere data. We use recent advances in laser engineering to measure sarcomere length through a minimally invasive fiber optic probe, which is much less traumatic than the current gold standard-tissue biopsies. Furthermore, we can collect data during movement and at multiple time points which allows us to better understand movement disorders in general. This talk will communicate the theory and validations of resonant reflection spectroscopy.

Fri, July 29

Speaker: Tamar Makin, PhD

Title: Adaptive and maladaptive reorganisation in amputees: Exploring the adult brain's opportunities for change
Abstract: Arm amputation provides a powerful model for studying plasticity, as it results in massive input and output loss consequential to losing a hand. Amputation also leads to profound changes in behaviour, driven by individuals’ need to compensate for severe disability (adaptive behaviour). Despite this strong behavioural pressure, research on amputation has been largely restricted to deprivation-driven (and supposedly passive) brain reorganisation, with little regard for the potential interaction between deprivation and behavioural related plasticity. As a consequence, sensory deprivation is widely held to cause maladaptive plasticity, resulting in phantom pain. Using a range of neuroimaging approaches I examine the extent to which experience modulates brain structure and function in amputees and individuals with congenital hand absence. I present evidence to challenge the proposed link between cortical reorganisation and phantom pain, and instead demonstrate preservation of topographic representations of the missing (‘phantom’) hand. I will show that phantom pain is associated with maintained representation of the phantom hand as opposed to brain plasticity, with potential implications on future treatment using neuromodulation. Instead I provide new evidence that adaptive behaviour using the intact hand, residual arm or a prosthetic limb leads to extensive reorganisation, both within and beyond the sensorimotor system. Based on this evidence, I suggest that plasticity in amputees is experience-dependant, and is not inherently maladaptive.

Fri, July 08

Speaker: Alexander Drobyshevsky, PhD

Title: Structural and functional perinatal brain injury in a rabbit cerebral palsy model

Abstract: His current presentation “Structural and functional perinatal brain injury in a rabbit cerebral palsy model” will describe a rabbit model of cerebral palsy. This model is one of the few mid-size clinically relevant animal models in the field of perinatal brain injury that results in motor deficits in newborns after global fetal hypoxia - ischemia, with the most robust and pronounced motor impairment among other the other models, including muscle hypertonia. The talk will discuss the clinical relevance of the rabbit model, pattern of the motor deficits, and the use of non-invasive fetal MRI biomarker to predict motor deficits, patterns and mechanism of injury, in particular structural and functional injury to white matter. In addition, the latest development will be presented regarding the effect of perinatal brain injury to structural and functional spinal cord maturation, as well as on spinal reflexes and muscle structure in affected limbs.

Thurs, June 30

Speaker: Sofia Triantafillou, PhD

Title: Integrative Causal Discovery

Abstract: Causal modeling allows predicting a system’s behavior not only under observation but also under intervention. Computational Causal Discovery aims to induce causal models, causal networks, and causal relations from observational data with limited or no interventions. Logic-based causal discovery is a novel, versatile approach in reconstructing causal networks. This approach accepts and reasons with multiple heterogeneous data sets that are obtained under different experimental conditions (interventions), and measure different quantities. Based on standard causal assumptions, associative patterns in the data that constraint the search space of possible causal model are translated in a logic program and solved using state-of-the-art SAT solvers. The method is shown to produce non-trivial predictions that are significantly validated in public data sets from a wide range of scientific domains.

Tue, June 28

Speaker: Anne Silverman, PhD

Title: Effects of Lower-Limb Amputation on Low Back Biomechanics and Dynamic Balance Control

Abstract: The Functional Biomechanics Laboratory uses both experimental and computational approaches to identify the underlying muscular actions that result in pathological movement patterns. In addition, we apply these tools determine how the musculoskeletal system adapts to clinical interventions, such as rehabilitation programs and assistive devices. In this talk, I will describe two of our ongoing projects applied to people with lower-limb amputations: (1) low-back biomechanics during walking and (2) comparison of the effects of passive and powered lower-limb prostheses on the regulation of dynamic balance. Our computational approach to estimating low back biomechanics has identified greater muscle forces, spinal loads and trunk-pelvis ranges of motion in people with an amputation. These results provide insight into potential mechanisms for low back pain development and motivate future investigations using a multiscale modeling approach. Through our investigation of dynamic balance, we have identified the key points during the gait cycle when falls are most likely to occur, what conditions result in the greatest fall risk, and how this changes with the use of passive and powered prostheses. These results have broadened our understanding of capabilities and limitations of current prosthetic devices. Both projects have characterized altered movement strategies in people with lower-limb amputations, and suggest device and training interventions that may mitigate risks of pain and falls following amputation.

Fri, June 17

Speaker: Andrew Kondrat, MA

Title: Navigating Grant Reviews with Research Ethics Consultations
Abstract:When submitting proposals for grants or NIH funding, researchers may receive responses from reviewers raising ethical issues that researchers will need to address. In this presentation, RIC researchers and staff from the Donnelley Ethics Program will discuss a recent research ethics consultation that addressed ethical concerns that an NIH grant reviewer had raised. The presentation will briefly give an overview of research ethics consultation then use this case to illustrate the process and utility of this service. Research ethics consultations can assist researchers in thinking through and responding to ethical concerns in order to strengthen their research proposal and proactively address potential ethical issues.

Panel-members:

Lynn Rogers, PhD; Co-investigator
Heidi Roth, PT, DHS, NCS; Research Therapist and Project Coordinator
Andy Kondrat, PhD; Ethics consultant and philosopher
Debjani Mukherjee, PhD; Ethics consultant and psychologist
Teresa Savage, PhD, RN; Ethics consultant and registered nurse

Tues, June 14

Speaker: Sameer Ashaie, PhD

Title: Modulating the Semantic System- A Combined tDCS and Eye-tracking Approach

Abstract: Confrontation naming is a complex process that involves multiple stages and can be initiated through multiple modalities. Models of confrontation naming have implicated both the anterior temporal lobes (ATL) and the temporo-parietal junction (TPJ) in the semantic stage of naming. I will discuss how we employed transcranial direct current stimulation (tDCS) to modulate the ATL and the TPJ to understand brain-behavior relationships involved in semantic stage of naming. Since the effects of tDCS are often very small or non-existent, we incorporated a novel method of combining tDCS with eye-tracking. The results permit me to consider how building a body of evidence regarding reliable effects of tDCS on cognitive task performance is important for establishing its efficacy as an intervention device in progressive neurogenic disorders and aphasia.

Fri, June 10

Speaker: Andrew Sawers, PhD

Title: Learning why we fall and why we don’t… one step at a time

Abstract: Measures of success and failure (i.e. you hit the target or you miss the target) provide a direct assessment of motor ability. In contrast, balance proficiency is typically evaluated using motor behaviors that are of insufficient difficulty to evoke failures in balance control. This limits our ability to: 1) quantify better walking balance and predict fall risk, and 2) identify the neuromechanical basis of “better balance” to guide the design of rehabilitation interventions. In this talk I will describe how my research has begun to address these important gaps. First I will discuss the development of a quick, in-expensive, and clinically viable test of walking balance proficiency based upon beam walking that can differentiate expert, novice, and amputee balance. Features of this test may address key limitations of existing clinical balance test that fail to predict fall risk in people with lower limb loss. Next, I will present results based on novel analyses of muscle activation patterns among professional ballet dancers (experts) and untrained novices performing a challenging beam-walking task. This data reveals that versatility rather than specificity of muscle coordination patterns underlies better walking balance, and that successful rehabilitation may require therapies that train patients to utilize common muscle coordination patterns across different motor behaviors rather than behavior specific motor solutions. Finally, I will conclude this talk by providing a brief overview of future projects in our lab.

Tue, June 7

Speaker: Salima Suleman, PhD Candidate

Title: Decision-making and Aphasia

Abstract: Investigation into the decision-making abilities of people with aphasia has diverse applications and potential for future inquiry. In this presentation, I will explore multiple facets of decision-making including: 1) the legal and clinical context for assessments of decision-making capacity; 2) a theoretical model of cognitive decision-making and the ways in which cognitive decision-making may be impaired in people with aphasia; 3) preliminary findings from my doctoral dissertation examining decision-making abilities of people with aphasia; 4) potential avenues for future research; and, 5) implications of current and future research findings on advocacy movements, theoretical understanding, and clinical practice for speech-language pathologists and other healthcare professionals.

Fri, June 3

Speaker: Maurizio Corbetta, MD

Title: Stroke, Brain Networks, and Behavior

Abstract:I will discuss results from a set of longitudinal studies in stroke aimed at understanding the behavioral, structural and functional imaging phenotype of stroke at the population level. I will show that, in contrast to traditional neurological teaching, impairment in stroke can be described by a small number of clusters of correlated behavioral deficits; that sensory-motor deficits are better predicted by structure while cognitive deficits are better predicted by large scale changes in functional organization. Finally, that recovery of function does not depend only on local mechanisms, as evinced from animal models, but also on the normalization of large-scale patterns of cortical dynamics.

Fri, May 27

Speaker: Thomas G. Sandercock, PhD

Title: Muscle Stiffness: Direct Mechanical Measurements in Animals Compared to Estimates Using Shear Wave Ultrasound

Abstract: Muscle stiffness plays an important role in motor control. Also, changes in stiffness are an indication of disease, making it a key clinical measurement. However, stiffness is difficult to assess in humans, so quantitative measurements are seldom made. Elastography, using ultrasound, offers the possibility of relatively simple measurements. In this talk I discuss the passive and active contributions to muscle stiffness. I will present measurements of short-range stiffness in animals and discuss how these data gave rise to a simple and accurate model. Finally I will present hypotheses relating elastography to short range stiffness, and present preliminary data testing these relations.

Mon, May 23

Speaker: Julio Hernandez Pavon, PhD

Title: Novel methods for characterizing large-scale networks with nTMS−EEG
Abstract:Navigated transcranial magnetic stimulation combined with simultaneous electroencephalography (nTMS−EEG) allows non-invasive cortical excitability, connectivity, and functional mapping studies with millisecond temporal and ~10 mm spatial resolution. However, due to the strong TMS-evoked scalp muscle artifacts, nTMS−EEG studies are mainly limited to areas close to the midline or analyzing only late latencies (>30 ms) when the muscle activity has ceased but, unfortunately, many of the neuronal events of interest have already subsided. These artifacts thus significantly hamper the utility of the method. In this talk, I will describe nTMS−EEG results from frontal and lateral (especially language-related) areas where we use independent and principal component analysis (ICA/PCA) based methods for removing and/or suppressing the muscle artifacts. I will also describe how to use the beamformer method for source localization of TMS-evoked EEG data to improve the interpretability of the data. These studies and methods open new avenues for developing new diagnostic and therapeutic tools in neurology and presurgical planning.

In my work, new modeling tools have been developed to predict the cross-scale, graded stiffening mechanisms that endow healthy the rotator cuff tendon-to-bone attachment with high resilience. I studied how tissue stiffness variations arise and alleviate stress concentrations. In addition, I investigated these mechanisms of load transfer to resolve the seemingly paradoxical underpinnings of the architecture of the rotator cuff across species, which provided further guidance for repair strategies. Finally, I investigated the biomechanical role of the functionally graded peri-cellular matrix (PCM) surrounding chondrocytes such as those that appear in the fibrocartilaginous region of the attachment of tendon to bone, and in articular cartilage. Results supported a hypothesis that this functionally graded peri-cellular matrix (PCM) may serve as a tool for controlling surface signaling of these cells and the dilatation of the PCM, the latter being vital for the flow of nutrients. Together, the results highlight the role of gradients in physiology, and the role of mechanics in guiding tissue engineered strategies for repairing these gradients.

Fri May 20

Speaker: Monica Perez, PhD

Title: The Corticospinal Pathway following Spinal Cord Injury

Abstract:The corticospinal tract is an important target for motor recovery after spinal cord injury (SCI) in humans. Using noninvasive electrophysiological techniques we have demonstrated the presence of reorganization in corticospinal projections targeting spinal motor neurons of muscles located close and at a distance from the injury site in individuals with chronic anatomically incomplete cervical SCI. Our physiological findings indicate that corticospinal transmission in intrinsic hand muscles change in a task-dependent manner and to a different extent in individuals taking and those who are not taking baclofen. We used this physiological information to develop noninvasive protocols to enhance transmission on residual corticospinal projections in humans with incomplete SCI. For example, we have precisely timed the arrival of descending and peripheral volleys at corticospinal-motoneuronal synapses of hand and leg muscles. We found that the arrival of presynaptic volleys prior to motor neuron discharge enhanced corticospinal transmission and hand and leg voluntary motor output. Modulation of residual corticospinal connections may represent a therapeutic target for enhancing voluntary motor output following SCI.

Mon, May 16

Speaker: Matteo Bertucco, PhD

Title: The effect of EMG-based augmented sensory feedback on motor functions in
Abstract: Brain injury at birth or during infancy can cause motor disability not only by a direct effect on motor areas of the brain but also by an indirect effect on the ability to acquire new skills during a child’s crucial learning period. Thus, a strong and unexplored potential exists for new therapeutic interventions to prevent or reverse abnormalities of motor learning. This long-term effect of a lesion is an almost completely unexplored area with importance not only to children, but also to adults who as children have suffered brain injury. Both motor and sensory deficits can impair skill learning. As a first step toward understanding the effect of early brain injury on subsequent skill learning, we aim to study the effect of sensory deficits on learning of upper and lower extremities movement tasks. Particularly we aim to determine whether EMG-based augmented sensory feedback can improve the rate of motor learning in the child’s natural environment and in a laboratory environment in children with movement disorders, such as cerebral palsy and dystonia. These results will help to refocus the current therapeutic paradigms by using the biofeedback technique as a motor exploration aid where sensory deficits can prevent the development of motor skills.

Fri, May 13

Speaker: Domen Novak, PhD

Title: Improving motivation, exercise intensity and motor learning in arm rehabilitation using competitive and cooperative exercises

Abstract: Although intensive physical rehabilitation is essential for recovery of motor function after neurological injuries such as stroke, most patients lack motivation and thus do not exercise frequently or intensely enough. This leads to suboptimal rehabilitation outcome, permanent limitations in functional abilities and a reduced quality of life. It is thus critical to motivate patients to more regularly and more intensely participate in motor rehabilitation exercises.
One way to motivate patients would be to allow them to compete or cooperate with other patients, therapists, friends or relatives. This presentation will provide an overview of our own research into technology-supported competitive and cooperative arm rehabilitation exercises. We first performed a study where 15 pairs of unimpaired subjects and 4 pairs of stroke survivors performed competitive and cooperative exercises with the ARMin arm rehabilitation robot. Both competition and cooperation resulted in higher enjoyment than exercising alone, and the subject's personality predicted whether they would prefer competitive or cooperative exercises.
We then performed a follow-up study where 29 patients with arm impairment exercised together with their friend, spouse or therapist using a home rehabilitation device. We found that competition can also increase exercise intensity in a single session, especially when competing against a loved one. As the next step, we are planning multisession studies to determine whether increased motivation and exercise intensity hold up over multiple sessions and whether they lead to better rehabilitation outcome.
In addition to potential benefits of competition, we are also studying how a patient could work together with a therapist or even another patient in order to improve motor learning. We have implemented a system that allows a therapist to demonstrate motions to a patient via two haptically coupled arm rehabilitation exoskeletons. Furthermore, the therapist can feel whether or not the patient is actively participating in the motion. The technical implementation and first evaluation of the system will be presented, and future clinical applications will be discussed.

Fri, May 6

Speaker: John Krakauer, MD

Title: What are we going to do about neurorehabilitation of stroke?

Abstract: I will talk about recent work in humans and non-human animal models suggesting we need to focus rehabilitation after stroke on the short time window of spontaneous biological recovery. The emphasis needs to be on restitution rather than compensation. A recent ongoing trial of early stroke rehabilitation will be described.

Thurs, May 5

Speaker: Fatemeh (Sally) Saadat

Title: Cross-scale modeling of functional grading in musculoskeletal tissues

Abstract: Interfaces in physiology often present transitional zones with gradual changes in composition, structure, and mechanical properties. For example, the attachment between tendon to bone features a unique interfacial region between that is critical for musculoskeletal physiological function. Unfortunately, this transitional tissue is not regenerated naturally after overuse injures, and in most cases, is followed by poor healing. My research aims to identify, through mathematical modeling of graded tissue regions, the ways that these regions contribute to physiological function, and the ways that the degeneration of these regions contribute to pathology. This fundamental insight can serves as a foundation for guiding repair and tissue engineering strategies for healing of graded tissue regions.
In my work, new modeling tools have been developed to predict the cross-scale, graded stiffening mechanisms that endow healthy the rotator cuff tendon-to-bone attachment with high resilience. I studied how tissue stiffness variations arise and alleviate stress concentrations. In addition, I investigated these mechanisms of load transfer to resolve the seemingly paradoxical underpinnings of the architecture of the rotator cuff across species, which provided further guidance for repair strategies. Finally, I investigated the biomechanical role of the functionally graded peri-cellular matrix (PCM) surrounding chondrocytes such as those that appear in the fibrocartilaginous region of the attachment of tendon to bone, and in articular cartilage. Results supported a hypothesis that this functionally graded peri-cellular matrix (PCM) may serve as a tool for controlling surface signaling of these cells and the dilatation of the PCM, the latter being vital for the flow of nutrients. Together, the results highlight the role of gradients in physiology, and the role of mechanics in guiding tissue engineered strategies for repairing these gradients.

Fri, April 29

Speaker: Amos Winter, PhD

Title: Using the constraints of emerging markets to create high-performance, low-cost assistive devices

Abstract:The MIT Global Engineering and Research (GEAR) Lab strives to understand the unique technical and socioeconomic challenges imposed by emerging markets, and then utilize engineering science and product design to create high-performance, low-cost, globally-relevant technologies. This talk will focus on GEAR Lab’s work designing wheelchairs and prosthetic limbs. The Leveraged Freedom Chair (LFC) is an all-terrain wheelchair that is 80% faster and 40% more efficient than conventional wheelchairs offered in the developing world, and can be completely fabricated out of low-cost materials and bicycle components. These attributes have made the chair a valuable product in poor countries, and a disruptive technology for the U.S. and European market. The talk will also cover GEAR Lab’s work to parametrically connect the mechanical design of prosthetic knees and feet to the anticipated biomechanical performance of amputees who use these devices. We have devised a way to predict the ideal torque profile for a low-mass prosthetic knee to induce able-bodied kinematics, and how this profile can be replicated using low-cost, passive mechanical elements. For prosthetic feet, we have created a new evaluation metric that builds on roll-over shape and incorporates kinematic and temporal information about the lower leg trajectory, in order to tune the stiffness and geometry of the foot to replicate able-bodied walking motion.

Fri, April 22

Speaker: Tom Ferrone

Title: Intellectual Property 101 at RIC

Abstract:This talk will give an overview of patents, trademarks, and copyrights at RIC. In addition, we will cover the basic agreements that RIC uses to support research, including non-disclosure agreements, subawards, joint development agreements, and IP licensing agreements.

Thur, April 21

Speaker: Dr. Sun Chung, PhD

Title: New Therapeutic Considerations for Mechanical Connective Soft Tissue Lesions: Biomechanical Approach to Low Back Exercise and Stem Cell Application for Tendon Tears

Abstract:Mechanical connective soft tissues (MCST), to name a few – intervertebral discs, knee meniscus, rotator cuff tendons, collateral ligaments, plantar fascia, and heel fat pad - play key roles in common musculoskeletal pain and disability. Life-long gradual deterioration of MCST has become a major problem as human life expectancy has significantly increased. Because MCST lesions are progressive with numerous injury-healing-reinjury cycles throughout a whole life requiring continuous management, conservative management principle seems more appropriate than operative approach. New strategies for conservative treatment of MCST lesions will be discussed. Firstly, optimal exercise therapies for low back pain will be discussed on the basis of biomechanical perspectives. Secondly, application of stem cells on tendon tears will be presented including animal experiment and clinical trial results.

Fri, April 15

Speaker: Dr. Jun Yao, PhD

Title: Cortical reorganization following interventions

Abstract: During the past ten years, surface electroencephalogram (EEG) signals have been used in our lab to study the cortical reorganization following nerve injury and interventions. This presentation tries to demonstrate evidence that changes in cortical activity following interventions can be used as a biomarker for the effectiveness of treatments.
Specifically, this presentation will disseminate cortical reorganization following 1) targeted reinnervation in amputee subjects, 2) progressive shoulder abduction loading intervention of reaching in chronic stroke subjects, and 3) ReIn-Hand-assisted task-specific upper limb intervention in individuals with moderate to severe stroke.
In general, our results suggest that an effective treatment is associated with the return of cortical features closer to a normal case.

Fri, April 8   

Speaker: Dr. Eric Hoffman, PhD

Title: Successful vs. failed remodeling of muscle: What genetic modifiers and synchrony may teach us
Abstract: Muscle, as with many tissues, is capable of remodeling. Remodeling can occur in terms of cellular adaptations (e.g. hypertrophy of myofibers), or can occur in the context of necrosis and regeneration. Muscle regeneration typically occurs in response to acute muscle injury, and in this context is 'episodic' (a single bout of degeneration and regeneration taking place over 2-3 week time frame). However, many of the clinical conditions of muscle involve chronic remodeling (inflammation and injury that does not resolve well). Chronic inflammation and remodeling of muscle (and many tissues) can lead to fibrosis - fibrotic replacement of the tissue that can be commensurate with failure of tissue function. Sometimes called 'failed regeneration', this process is quite striking in Duchenne muscular dystrophy - an inborn error of muscle that leads to repetitive bouts of degeneration/regeneration, fibrotic replacement, muscle wasting and an early death. We sought to understand the molecular underpinnings of failed regeneration in muscle. We found that episodic remodeling and successful regeneration share nearly all molecular features with chronic remodeling and failed regeneration. However, the major distinction was the staging of molecular processes as a function of time. Whereas certain key elements of episodic remodeling each have their 'place and time' (synchronous remodeling), chronic inflammation and unsuccessful remodeling is a dyssynchronous process, with wrong molecular players playing roles at the wrong time and wrong place. This model is shown experimentally through re-creation of asynchronous remodeling in normal mouse muscle. The model is then extended to include studies of asthma and lung inflammation, as well as the mechanism of action of corticosteroids (a pharmacological variant of the diurnal hormone, cortisol).
Host: Dr. Leiber

Tue, April 16

Speaker: Majed Samad

Title:  A cognitive perspective of bilingual language control: An evolving field in language rehabilitation?

Abstract:  Two separate lines of research have widely studied, in isolation, language control and cognitive control in the bilingual brain. With a growing bilingual population, it is imperative to understand the link between the two systems (linguistic and cognitive) not only to recognize the consequences bilingualism has on language processing and production, but also because it holds important implications for language rehabilitation. The first section of the talk will provide a brief overview of the mechanisms of bilingual language control across the life-span. This section will highlight the role of domain-general executive control, especially individual differences in inhibitory control, in selecting words from the contextually appropriate language. The second section will briefly focus on the clinical implications of the interplay between cognitive and linguistic systems for effective language rehabilitation.

Wed, March 30  

Speaker: Dr. Arthur (Art) English, PhD

Title:   Enhancing axon regeneration in peripheral nerves with exercise

Abstract:  Moderate exercise is an experimental rehabilitation treatment that enhances axon regeneration following peripheral nerve injury. The effectiveness of exercise in this regard relies on its promotion of neuronal brain-derived neurotrophic factor and on androgen receptor signaling. Increased neuronal activity is adequate to promote regeneration in injured nerves, but the dosing of activity and its relationship to neurotrophins and sex steroid hormones are less clear. Effective translation of these therapies will require the development of principles associated with their cellular mechanisms.

At the end of this lecture, you should be able to:

  1. Show how moderate daily exercise may be used to enhance recovery from peripheral nerve injuries.
  2. Identify the evidence that neuronal brain-derived neurotrophic factor and androgen receptor signaling are required for the effectiveness of these treatments.
  3. Define how knowledge of these cellular mechanisms might contribute to promoting the clinical translation of these therapies

Fri, March 25

Speaker: Dr. James (Jim) Elliott, PT, PhD

Title:   Quantifying injury following Motor Vehicle Collisions…making the invisible, visible

Abstract:  Integrated and global research efforts involving a diverse group of professionals has realized that the prediction of recovery following motor vehicle collisions involves a complex interplay between biological, psychological, and environmental processes. Jim and his lab are working on new imaging based methods for making the mostly invisible experience of pain and disability more visible and meaningful at the level of the clinician. In this session, Jim will speak about emerging advancements in the clinical assessment of the patient with suspected head/neck trauma.

OBJECTIVES:

Be able to integrate current best evidence into effective assessment, sub-group classification and management of the patient with acute and chronic traumatically induced neck disorders.

To highlight recent evidence of physiological changes in spinal cord and skeletal muscle tissues following whiplash injury.

Integrate this new knowledge into a ‘triangulated’ understanding of a patient’s pain complaint, and develop effective management strategies to prevent the transition from acute to chronic pain and disability.

Fri, March 18

Speaker: Dustin Tyler, PhD

Title:   Restoring Touch: Development and Clinical Implementation of Advanced Neural Interface Technology

Abstract:  Loss of limb, spinal cord injury, stroke, cerebral palsy, Parkinson’s disease, and other neurological impairments result in loss of sensation and of function for millions of people every year with no prospect of help from pharmacological or traditional surgical treatment. Neural prostheses reconnect sensory feedback and motor function to these patients. The link between the man and the man-made, i.e. the neural interface, is a critical component to system performance and capability. Restoration of somatosensation and autonomic function, with the potential to replace pharmacological approaches, is only possible with direct neural interfaces. The current pipeline of state-of-the-art interface approaches, from concept to clinical implementation, will be highlighted. For nearly 2 million people in the US and 185,000 more each year, the loss of sensation is one of the most significant effects of limb loss resulting from trauma or vascular disease. We have connected sensors in the prosthesis directly to the user’s nerves, restoring sensory feedback and closed-loop robotic control to individuals with upper extremity limb loss. Selective stimulation of small regions of the peripheral nerve provides spatial resolution in the perceived sensation and development of new pulse coding allows control of the quality of the sensation. Sensation improves fine task control and Individuals now feel tactile sensation, have improved control, sense motion, and have ability to discriminate texture. In the words of a subject, they can, “feel [my] hand for the first time since the accident,” and “feel [my] wife touch my hand.”

Wed, March 14

Speaker: Jonathan Rivnay, PhD

Title: Organic electronics for neural interfacing
Abstract: The interface between electronics and the human brain represents one of the most significant technological and scientific endeavors of our time. Plugging into the brain, one of nature’s most complex and least understood creations, promises to reveal how we function and to unlock new routes for diagnosis and treatment. Organic electronic materials possess attractive properties for favorably bridging electronics and brain tissue; they are better mechanically matched to tissue than inorganic materials, and support mixed ionic/electronic conduction, allowing for efficient bi- directional communication with the brain. I will address how these unique properties can be implemented in active devices that advance the current state of the art in recording and stimulation of brain activity. Organic electrochemical transistors, for example, are ideal platforms for neural interfacing due to their high power gain. I harness the volumetric gating of these devices to demonstrate human electroencephalography (EEG) measurements with significant signal enhancement at low frequencies. I then demonstrate the use of conducting polymers and polyelectrolytes as active elements in organic electronic ion pumps -- devices which allow for localized electrophoretic delivery, without the adverse effects of fluidic delivery. I show that delivery of an endogenous inhibitory neurotransmitter can stop seizure-like activity locally in brain tissue. Finally, I demonstrate how the ionic and electronic transport properties of organic electronic materials can be controlled with chemistry and processing techniques. These findings set the stage for a more general fundamental understanding of mixed conduction in organic materials, which is necessary for rational materials and device design for far-reaching bioelectronic applications.

Fri, March 11

Speaker: Ning Jiang, PhD 

Title: Towards robustness myoelectric control: some preliminary studies
Abstract: sEMG, in addition to its inherent variability, is influenced by a number of factors when used as the control source of prosthetic devices. These factors include electrode positions, positions, joint-angles of limbs and trunk, contraction level, user adaptation, just to name a few. It has been shown by researchers at SMPP and others that these changing condition of these factors can be detrimental for myoelectric control algorithms that do not account for these effects. This is one of the a key challenges in myoelectric control. In this talk, I will discuss several studies by me and my colleagues in Germany and China in addressing this challenge.

Wed, March 9

Speaker: Robert Gregg, PhD

Title: High-Performance Control of Lower-Limb Prosthetics and Orthotics: Lessons from Robot Locomotion

Abstract: The gait cycle is typically viewed as a periodic sequence of discrete events, starting with heel contact during initial stance and ending with knee extension during late swing. This convention has informed the design of control strategies for powered prosthetic legs, which almost universally utilize a finite state machine to switch between several distinct controllers throughout the gait cycle. This paradigm requires substantial time and effort to tune the many controller and switching parameters, and it is not robust to perturbations that push the gait cycle forward or backwards (i.e., changes in phase). This makes it difficult to 1) study the control mechanisms of non-steady human gait and 2) design wearable robots that respond in harmony with the human user. Instead of discretely representing the phases of gait, a continuous representation of phase could parameterize larger portions, or the entirety, of the gait cycle. In particular, the concept of a mechanical phase variable has been successfully used to control the progression of leg joints in dynamic walking robots. However, it is unclear which phase variable, if any, could provide a robust representation of phase for non-steady human locomotion. This talk will share the results of a perturbation study with 10 able-bodied human subjects, observing that a specific mechanical variable can robustly parameterize the human gait cycle with very high correlation. This phase variable is then implemented in a unified controller to synchronize prosthetic joint patterns with the location of the human body in the gait cycle. This approach is validated by experiments with a human subject walking on a custom powered knee-ankle prosthesis at variable speeds. Having unified the control of specific tasks, ongoing work aims to achieve task-invariant control of wearable robots through energy shaping methods.

Fri, March 4

Speaker: Helena Fordell, MD

Title: RehAtt – a multi sensory scanning training in Virtual Reality for neglect, associated to increase of frontal neuronal activity in chronic neglect
Abstract: A presentation and demonstration of a visuo spatial scanning training enhanced by directed visual, audio and tactile stimulation cues and feedback,
including visuo-motor activation designed in a Virtual Reality 3D game. The user perceived an interactive 3D environment using a desktop computer, a monitor,
3D glasses and a force feedback interface by the use of Phantom Omni, robotic device. A first evaluation has been made in 15 subjects with chronic neglect in tests, behavioral assessment and fMRI. Training with the VR-method improved spatial attention and showed transfer to improved spatial attention in activities of daily living in chronic neglect. A fMRI study was performed in 12 of the patients and showed how patients improved their performance in the Posner fMRI task. In addition, patients increased their task-evoked brain activity as a consequence of the VR interventions in an extended network including prefrontal and temporal cortex during attentional cueing. In resting state during fMRI the preliminary results show a significant improvement in connectivity in the dorsal attention network after training. In a Proof of Concept study founded by the Swedish government we visit key-opnion leaders for feedback about design and feasibility.

Fri, Feb 19

Speaker: Ken Paller, PhD

Title:   Off-Line Learning via Sleep-Based Memory Re-Procesing
Abstract:  The benefits of learning depend on neurocognitive processing of various sorts, including processing engaged well after the overt activities of acquisition and practice. The many hours we spend sleeping may provide a vital opportunity for such off-line processing. Although most memories that we form each day are later forgotten, some are stabilized and can endure indefinitely. Some memories may remain retrievable particularly because they are robustly reactivated and consolidated during sleep. In experiments utilizing subtle auditory stimulation, we can selectively encourage memory reactivation during sleep, modulating various types of learning as measured later. These strategies have opened up new opportunities for investigating learning, with the potential for novel clinical applications such as in stroke recovery.

Thur, Feb 18

Speaker: Megan O’Brien, PhD

Title: The neuroeconomics of error and effort in movement

Abstract: Consider that the goal of a voluntary movement is to put the body in a more valuable state, so that our movement decisions are based on maximizing rewards and minimizing any costs incurred while pursuing those rewards. Neuroeconomic principles are well-suited for describing movement behavior and control in this way, allowing us to quantify the utility of movement as a summation of the movement’s rewards and costs. The reward of a movement depends on the value of the object attained as well as the probability of obtaining it. The cost of a movement can be naturalistically represented as the effort spent in executing the motor commands. Then, the utility of a movement is determined by getting as much reward as possible while expending as little effort as possible. Importantly, these rewards and costs are susceptible to subjective valuation (wherein individuals may assign more or less value to them than their objective worth), which in turn affects movement behavior. Formalizing movement as a decision-making process allows us to compare the subjective valuation of these rewards and costs between tasks, domains, and populations.
In this talk, I will describe human movement using a neuroeconomic framework. I will present several novel studies that contribute to a broader question: how do subjective interpretations of movement rewards and costs manifest in our behavior? Specifically, I will discuss how implicit threat affects our weighting of the probability of movement error, and how a well-known cognitive bias affects our valuation of movement effort.

Tue, Feb 16

Speaker: Majed Samad

Title: Models of own-body perception and applications to the clinic

Abstract: The body is a fundamental anchor in every individual's perceptual reality, possessing privileged processing status and underlying much of what may be called the sense of selfhood. We have investigated the computational rules governing the integration of information that relates to one's own body using useful illusions such as the rubber hand illusion and a novel visual-tactile variant of the ventriloquist illusion, and shown that an extension of the causal inference model that has previously been shown to account for audiovisual integration can also account for the rubber hand illusion, with two experiments confirming the model's predictions. In addition to modeling, we have also attempted to utilize psychophysical paradigms to improve diagnosis of focal hand dystonia and cervical dystonia, as well as attempt to improve outcomes through the use of proprioceptive perceptual learning. Finally, we are currently conducting an EEG study to uncover the oscillatory markers of multisensory integration through the use of a novel feature selection algorithm and multivariate classification methods with the aim of diagnosing abnormalities of integration in disease populations and devising interventions for their treatment. Overall, these results demonstrate the utility of 1) computational methods for improving our understanding of neural information processing, and 2) psychophysical approaches to improving medical outcomes for patients with challenging clinical disorders.

Fri, Jan 22

Speaker: Keith Gordon, PhD

Title: Robotic Interventions to Enhance Locomotor Stability

Abstract: All mechanisms for stabilizing human walking are not equal. Often individuals with neurologic impairments choose stabilization strategies that inherently sacrifice critical components of community ambulation including speed and energetic efficiency. This is in contrast to neurologically intact individuals who utilize locomotor strategies that are concurrently stable, agile and efficient. I will present a unique perspective on how training environments can be structured to encourage individuals with neurologic impairments to actively practice “higher level” stabilization strategies that this population would typically avoid. Specifically, I will discuss a simple robotic tool we have developed to modulate the requirements for stabilization during walking and demonstrate how we are leveraging this device to drive individuals to adapt varying mechanisms for stabilizing gait.

Fri, Jan 15

Speaker: Thomas Howard, PhD

Title: Learning Models for Robot Decision Making

Abstract: The efficiency and optimality of robot decision making is often dictated by the fidelity and complexity of models for how a robot can interact with its environment. It is common for researchers to engineer these models a priori to achieve particular levels of performance for specific tasks in a restricted set of environments and initial conditions. As we progress towards more intelligent systems that perform a wider range of objectives in a greater variety of domains, the models for how robots make decisions must adapt to achieve, if not exceed, engineered levels of performance. In this talk I will discuss progress towards model adaptation for robot intelligence, including recent efforts in natural language understanding for human-robot interaction.
This presentation will introduce a framework for integrating mechanical characterization of passive prostheses, human subject testing, and numerical simulation to study these relationships and accurately classify prosthesis function in an effort to optimize clinical prescription guidelines and prosthesis designs. Methods of prosthesis mechanical characterization to inform research, clinical prescription and cost justification will be presented, as well as studies that use systematic approaches to explore the effects of isolated prosthesis properties on user performance.

Fri, Jan 8

Speaker: Matthew Major, PhD

Title: Exploring the relationships between lower-limb prosthesis mechanical properties and user performance for clinical prescription and prosthesis design optimization.

Abstract: Prosthetists are confronted with the universal challenge to select from a wide variety of commercially-available lower-limb prostheses to best help patients reach their functional and health-related goals. With more prosthetic components being developed each year, this challenge becomes increasingly difficult, particularly as the fundamental relationship between prosthesis mechanical properties (i.e., stiffness, damping, and roll-over geometry) and user performance (e.g., walking dynamics, muscle activation patterns, and metabolic cost) are still poorly understood. This lack of understanding hinders the development of future prostheses that are designed to maximize walking efficiency. Furthermore, there is no standardized method for the mechanical testing of prostheses for accurate and reliable classification based on functional characteristics (e.g., energy storage-and-return, multi-axial, etc.). Without such standardized methods, clinical prescription, recommendation, and cost justification suffer from ambiguity and may result in suboptimal patient rehabilitation outcomes. Characterization of prosthesis mechanical properties provides a critical means for systematic exploration of the effects of these properties on the biomechanical and physiological performance of lower-limb prosthesis users, and allows for accurate and reliable prosthesis functional classification. Ultimately, improved understanding of this paradigm will inform clinical prescription guidelines and facilitate development of optimal prosthesis designs to enhance the mobility and health of lower-limb prosthesis users.

This presentation will introduce a framework for integrating mechanical characterization of passive prostheses, human subject testing, and numerical simulation to study these relationships and accurately classify prosthesis function in an effort to optimize clinical prescription guidelines and prosthesis designs. Methods of prosthesis mechanical characterization to inform research, clinical prescription and cost justification will be presented, as well as studies that use systematic approaches to explore the effects of isolated prosthesis properties on user performance.