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SMPP Seminars 2014

To schedule a seminar at SMPP, please contact Margaret Duff. Her email is ( )

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

Fri, April 25

Speaker: Song Joo Lee, Ph.D.

Title: Effects of Six-Week Pivoting Neuromuscular Training on Offaxis Neuromechanical Properties in Males and Females

Abstract: Musculoskeletal injuries of lower limbs often occur in pivoting sports and females are at higher rate of injuries than males. However, there is a lack of information on gender differences in offaxis neuromechanical properties in axial plane pivoting and frontal plane sliding and methods to improve offaxis neuromuscular control under injury related situations. The goal of the research was to investigate effects of genders and 6 week neuromuscular training on lower limb offaxis neuromechanical properties.

First, gender differences of proprioception and neuromuscular control in pivoting under external perturbations, and offaxis neuromuscular control under slippery conditions were investigated. Compared to males, females demonstrated lower proprioceptive acuity under weight-bearing and decreased pivoting neuromuscular control with higher pivoting instability, lower leg pivoting stiffness, and entropy of time to peak EMG in gastrocnemius muscles during stepping under external perturbations and decreased offaxis neuromuscular control during stepping under slippery conditions.

Second, effects of 6-week pivoting neuromuscular training on proprioception and neuromuscular control under external perturbations and slippery conditions were investigated. Six-week pivoting neuromuscular training improved proprioceptive acuity and neuromuscular control under injury-related situations, and females benefited more from the training.
The secondary goal of the research was to investigate effects of 3D knee geometries and gender dependent tibial external rotation laxity on the susceptibility of ACL impingement against the femoral intercondylar notch using a finite element knee model.Our findings suggest that 3D knee geometries and joint laxity alter biomechanical contact properties between the ACL and femur.

Overall, the research investigated effects of gender differences and 6-week neuromuscular training to understand potential modifiable and non-modifiable risk factors of musculoskeletal injuries, ACL injuries in particular. This study may help understand factors contributing to musculoskeletal injuries in females and males, and develop neuromuscular training strategies to improve neuromuscular control and proprioceptive acuity.

Host: Dr. Zhang

Fri, April 18

Speakers: Lois Huggins and Kathy Galvin

Title: Communicating With Influence

Abstract:   Communicating With Influence highlights effective communication skills, including Active Listening and Assertion, to enhance participants’ communication and interpersonal skills, and to increase participants’ ability and confidence to provide feedback to others.  It is an interactive one-hour session.

Host: Dr. Kuiken

Wed, April 16

Speaker: James Buffi

Title: Using Biomechanical Simulation and Modeling to Calculate Potential Muscle Contributions to Elbow Varus Torque during Baseball Pitching

Abstract: Failures of the ulnar collateral ligament (UCL) and damage to the osseous articulation of the elbow are common and severe elbow injuries that occur in baseball pitchers as a result of the excessive elbow valgus torque imposed by the baseball pitching motion. Despite high injury risk to elbow musculoskeletal structures during pitching, research characterizing muscle contributions to protecting this joint during the pitching task is extremely limited. One reason for this limitation is that common experimental methods in cadavers and living subjects are not sufficient to understand muscle function in this high-performance, high-velocity, multiarticular task. Consequently, biomechanical modeling and simulation are required to better understand individual muscle contributions and associated injury implications. The goals of this project were to develop a simulation framework for the baseball pitching motion and to use this framework to characterize potential muscle contributions to protecting the elbow joint during this complex task.

To achieve these goals, an upper-extremity and a whole-body musculoskeletal model were developed for use in a quasi-static sensitivity analysis and a forward dynamic analysis, respectively. Additionally, because an important medial elbow muscle (flexor digitorum superficialis) inserts in the hand, a method was defined and evaluated for recording hand motion with an instrumented glove. The quasi-static simulation indicated that adopting a flexed elbow posture at a critical time point in the pitching motion substantially decreased the ability of the medial elbow muscles to generate protective varus torque. Therefore, a more extended elbow posture may mitigate elbow injury risk. In a forward dynamics simulation of a single subject’s pitching motion, activation and contraction dynamics limited the ability of the medial elbow muscles to actively counter the rapid increase in elbow valgus torque imposed by the pitch. In simulation, it was demonstrated that the intrinsic stiffness properties of muscles that allow them to instantaneously respond to perturbations may be an essential mechanism necessary to protect baseball pitchers from UCL injury. Overall, the simulation framework developed in this project represents an essential advancement to the field of pitching biomechanics that, for the first time, allows researchers and clinicians to evaluate potential contributions of the elbow muscles.

Host: Dr. Murray

Wed, April 9

Speaker: Yunju Lee

Title: On the Behavior of the Adult Upper Extremity under Impulsive End-Loads?

Abstract: Falls in the elderly are a serious socioeconomic problem for which costs have reached $30 billion/year in direct costs alone. The reality of aging is that one loses about 1% of muscle strength/year after the age of 55 years. When this loss of muscle strength is combined with obesity, the strength-to-weight ratio becomes unfavorable and the upper extremity muscles may no longer be able to prevent the arms from buckling at the elbows in a fall. The result can be head injury and even death.

In this seminar we shall review a novel apparatus and the experimental methods we used to identify the viscoelastic properties of active upper extremity muscles in healthy young and older adults identified via dynamic optimization techniques. We shall discuss in silico studies that employed ADAMS multi-body dynamics computer models to show that older females have a 25% lower arm buckling load than young females of the same body size. We will also examine the question of whether the muscle reflexes are fast enough to stiffen the arm protraction muscles during a fall arrest. Finally we discuss the utility of this research in providing exercise or rehabilitation goals for the upper extremities of older adults.

Host: Dr. Zhang

Tues, April 8

Speaker: Nathalia Headley, David Wingate, and David Zembower

Title: Conducting Investigational Drug Studies

Abstract: This presentation will focus on accomplishing the following learning objectives:

  • Debriefing on the Q2 FY2014 Corporate Compliance Investigational Drug Study Audit
  • Identify the key requirements in the FDA and IRB regulations, and RIC policies
  • Identify what your primary roles and responsibilities are in conducting investigational drug studies
  • Discuss helpful tips and pointers to run your drug study effectively and protect human subjects
  • Identify your primary references and resources, and know where to go and who to contact for additional help

Fri, April 4

Speaker: Christian Ethier, PhD

Title: Brain-controlled muscle stimulation: a neuroprosthesis for the restoration of grasp function after paralysis
Abstract: We have developed a neuroprosthesis that allows monkey subjects to pick up and move objects despite a peripheral nerve block causing complete paralysis of the flexor muscles below the elbow. The restored voluntary movement was achieved using signals recorded from approximately 100 neurons in the primary motor cortex to control electrical stimulation of the paralyzed muscles. After nerve block, the monkeys were able to use the neuroprosthesis to perform a functional grasping task with a success rate approaching their normal performance, whereas they were essentially unable to complete this task without assistance. We are now investigating adaptive decoders to facilitate the implementation and improve the performance of this neuroprosthetic system in chronically paralyzed subjects. In human spinal cord injured patients, such a system could provide natural control of arm and hand movements through normal cognitive processes, and greatly enhance the patients' independence and overall well-being.

Host: Dr. Miller

Fri, March 21

Speaker: Suzanne Sokalski

Title: IRB 101

Abstract: Please join us for a discussion of:

  • When does the IRB need to be involved?
  • What kind of review is appropriate for your project?
  • What are IRB reviewers looking for?
  • Practical tips for submitting in eIRB
  • Your questions

Fri, March 14

Speakers: Paul Wanda, PhD and Matt Perich

Title and abstract (Paul): Signatures of uncertainty in motor and dorsal premotor cortex of non-human primates

Behavioral studies show that humans can combine noisy information from previous experience and current feedback to guide their movements in a near Bayes-optimal manner. However, little is known about the neural encoding of uncertainty. Here, we designed a behavioral paradigm to test several theoretical models with electrophysiological data. We trained macaques to perform a modified center-out reaching task and found evidence of Bayes-like weighting of sensory feedback in the monkeys’ behavior. We recorded neural signals from macaque dorsal premotor cortex (PMd) and primary motor cortex (M1) using chronically-implanted, 96-channel multi-electrode arrays. As feedback uncertainty increased, we found that both firing rates and across-trial rate variability increased across the population of recorded PMd neurons, initiating during planning (non-movement) phases. These results suggest a complex neural code for uncertainty in motor areas.

Title and abstract (Matt): Neural correlates of adaptation to dynamic and kinematic perturbations in motor cortex

Coordination of visually guided movements requires a transformation from planned kinematics to executed dynamics that must be learned through trial and error and the adaptation of an internal model. Thus motor adaptation may be mediated by adjusting the computations performed by M1 and PMd. The differing functional roles of M1 and PMd in coordinating movement suggest different roles in motor adaptation. To test this, we compared neural activity during adaptation to two reaching perturbations: a static visual rotation (VR) or viscous curl force field (CF). The CF affected only the dynamics of the movement, and when fully adapted, the kinematic trajectories were identical to the unperturbed reaches. In contrast, the VR required new planned trajectories to reach the targets. We described the spatial tuning of each recorded neuron using a preferred direction (PD). We found that when correlating activity with the actual direction of hand movement, M1 PDs were constant during adaptation to both perturbations even as task performance improved. PMd neurons, in contrast, showed an apparent change in tuning with the same analysis methods. However, PMd tuning was stable during adaptation if the tuning was instead calculated with respect to the target direction. These results highlight the functional differences between PMd and M1 in coordinating limb movements, where M1 activity relates to the dynamics of the movement and PMd relates primarily to the goal.

Host: Dr. Miller

Fri, March 7

Speaker: Ghulam Rasool

Title: Task-specific Muscle Synergies – A Novel Framework for Task Discrimination

Abstract: The control of an artificial robotic limb using myoelectric signals from leftover muscles in amputees is a challenging problem in rehabilitation engineering. We present a novel scheme to tackle the problem by employing task-specific muscle synergies and state-space representation of the neural signals. The proposed framework incorporates information about muscle configurations, e.g., muscles acting in agonist /antagonist pairs or synergistically, using the hypothesis of muscle synergies. The neural drive, comprised of muscle synergy activation coefficients, is modeled as the unknown latent system state. Subsequently, we employ a recursive Bayesian technique to estimate the neural drive. The estimated neural drive is later used to discriminate between various tasks. The task discrimination decisions by the proposed scheme are further improved by a post-processing routine using posterior probabilities. The proposed algorithm is robust and computationally efficient yielding a discrimination decision in approximately 3 ms. Real-time performance and controllability of the algorithm was evaluated using the targeted achievement control (TAC) test. Based on the results of this study, the proposed algorithm outperformed the commonly employed linear discriminant analysis (LDA) algorithm in off-line accuracy (p<.001) and real-time performance (p<.01) for single as well as multi-degree-of-freedom (DOF) tasks.

Host: Dr. Rymer 

Thurs, March 6

Speaker: Jeremy Newkirk, PhD

Title: Measurement and Quantification of the Human Shoulder Girdle Motion and Design of a Humanoid Shoulder Girdle Mechanism with Minimal Actuation

The shoulder girdle plays an important role in the large pointing workspace that humans enjoy. The goal of this work was to characterize the human shoulder girdle motion in relation to the arm and recreate it with a humanoid shoulder girdle mechanism so as to ultimately improve the human-like motion of humanoids. The overall motion of the human shoulder girdle was characterized based on motion studies completed on test subjects during voluntary (natural/unforced) motion. The collected data from the experiments were used to develop surface fit equations that represent the position and orientation of the glenohumeral joint for a given humeral pointing direction. These equations completely quantify gross human shoulder motion relative to the humerus. The equations are presented along with goodness-of-fit results that indicate the equations well approximate the motion of the human glenohumeral joint. This is the first time the motion has been quantified for the entire workspace, and the equations provide a reference against which to compare the motion of candidate humanoid shoulder girdle mechanisms. A novel 2-degree-of-freedom parallel mechanism composed of two platforms, one leg with two revolute joints and two legs with spherical-prismatic-spherical joint combinations (1-RR, 2-SPS), is introduced and analyzed. The results from the data collection were used to find the optimal configuration for this mechanism to mimic human shoulder girdle motion. The results indicate that the optimized mechanism well approximates the motion of the human shoulder girdle, making it the first mechanism that replicates human shoulder girdle motion with minimal actuation. The methodology for incorporating the shoulder girdle mechanism into the shoulder-elbow complex is presented. The kinematic equations of motion for the complex were derived, and a qualitative analysis was completed that indicates the motion of the full system is similar to that of the human shoulder-elbow complex. The work presented here lays the groundwork for replicating complex human shoulder girdle motion with a relatively simple robotic system. 

Host: Dr. Kuiken

Tue, March 4

Speaker: Ross Arena, PT, PhD

Title: CPX: Reinventing Clinical and Research Applications

Abstract: Cardiopulmonary exercise testing (CPX) is clinically indicated for several diagnoses/suspected diagnoses with a wealth of scientific evidence supporting its value.  Moreover, the use of CPX as a primary or secondary research endpoint, when an exertional assessment is needed, is readily justifiable.  The appropriate application of CPX for clinical or research purposes has been somewhat hindered by the high volume of data generated and a lack of clarity on which variables are most relevant for a given test indication.  This presentation is based on the recent EACPR/AHA joint statement that significantly consolidates CPX interpretation based upon test indication and current evidence. 

Host: Dr. Rymer 

Fri, Feb 28

Speaker: Reza Shadmehr, PhD

Title: A memory of errors in sensorimotor learning

Abstract: When performing a motor task, experiencing an error results in a change in motor behavior on the next trial. Models of this behavior typically feature one or more fixed error-sensitivity parameters that describe the percentage of the error that is accounted for in the next trial. However, these models of learning cannot explain recent motor control results in areas such as savings, meta-learning, and saturation in the amount that is learned from a sensory prediction error. Here we show that the brain modulates, through a principled mechanism, how much it is willing to learn from error. To understand the rules that govern changes in error-sensitivity, we perform experiments which manipulate the statistics of the perturbations, altering the history of experienced errors, and record its effects on error-sensitivity. We find that positive lag-one autocorrelations up-regulate error-sensitivity local to the specific errors that were experienced, whereas negative autocorrelations down-regulate error-sensitivity. Our results suggest that motor memory is composed of both a memory of actions and a memory of previously experienced errors. This memory of errors sheds new light on a number of puzzling observations, including savings and meta-learning.

Host: Dr. Miller 

Fri, Feb 21

Speaker: Yasin Seven, PhD

Title: Neuromotor Control of the Diaphragm Muscle: Functional Recovery after Cervical Spinal Cord Injury

Abstract:  Diaphragm muscle (DIAm) is activated during ventilatory and non-ventilatory motor behaviors, which require different levels and patterns of central drive as well as involve different central pattern generators. DIAm motor units are diverse in their mechanical and fatigue properties. Therefore, how these motor units are being recruited determines the force and fatigability of muscle contractions. DIAm single motor unit activity was assessed in rodents exhibiting spontaneous recovery after spinal cord injury across resting breathing, hypoxia-hypercapnia, sighs and airway occlusion.

Due to limitations of single motor unit recordings, compound EMG was simultaneously recorded to measure DIAm activity. So far, it is unclear how much information can be obtained about motor unit activity using compound EMG. DIAm EMG power spectral density shifted to higher frequencies with the recruitment of fatigable fast-twitch motor units during sneezing (maximal DIAm force). Additionally, the non-stationary period of DIAm EMG reflected the time period where DIAm motor units are being recruited.

Host: Dr. Rymer

Tue, Feb 18

Speaker: Robert Ajemian, PhD

Title: The Perpetual Motion of Motor Memories and How they Differ Profoundly from Computer Bytes

Abstract: From throwing a baseball to playing the piano to using the latest I-Phone keypad, humans are constantly acquiring novel sensorimotor skills throughout the course of their lives.  A fundamental goal of neuroscience has been and continues to be an elucidation of neuroplasticity – that is, the neural mechanisms underlying motor memory acquisition and storage.  For over a half-century, the computer metaphor has shaped the neuroscience community’s thinking regarding the transfer and storage of information.  According to this viewpoint, the nervous system lays down a synaptic trace during learning, and, while the details of this process are quite complex (LTP, LTD, spike-timing dependent plasticity, etc.), the interpretation of the memory is unambiguous.  The memory IS the desired synaptic trace.  Further, as long as this trace remains intact, so too does the memory.  However, there are clear functional and architectural differences between the inorganic circuitry of a computer chip and the biochemical environment of a neuron.  From a functional standpoint, signal processing in computer chips is virtually noiseless, conducted at transmission velocities approaching the speed of light, and wholly reproducible from one trial to the next.  In contrast, neurons are both noisy in their signal processing and slow in their signal transmission, while their constitutive components – including the memory-related dendritic spines and axonal boutons – constantly undergo wholesale molecular turnover.  From an architectural standpoint, computers utilize local circuit connectivity in an essentially serial manner, whereas neurons in our brain are highly interconnected for parallel processing (each neuron connects, on average, to 10,000 other neurons).  With this perspective in mind, we propose a uniquely biological theory of motor memory formation based on three assumptions: 1) neural signal processing and synaptic change are both extremely noisy processes, 2) synapses are constantly being modified through learning-dependent mechanisms at extremely high rates (hyperplasticity), and 3) the motor system is highly redundant at all levels.  What emerges from this framework is a unique dynamic interpretation of sensorimotor memory: memories are defined not by fixed patterns of synaptic weights but, rather, by non-stationary synaptic patterns that fluctuate coherently.  The predictions this theory makes are subsequently compared to the known physiological and behavioral properties of the human sensorimotor system.

Host: Dr. Mussa-Ivaldi

Fri, Feb 14

Speaker: Brenna Argall, PhD

Title: Selective and Customizable Autonomy for Rehabilitation Robots

Abstract: For decades, the potential for automation---in particular, in the form of ”smart” wheelchairs---to aid those with motor, or cognitive, impairments has been recognized. The introduction of partial automation makes an assistive machine into a sort of robot, that shares control with the human user. This human-robot team is truly heterogeneous: the goal of the automation is to fill a gap left by the sensory/motor impairment of the user. This talk will identify opportunities for machine learning, artificial intelligence and robot autonomy to be leveraged within rehabilitation and assistive robotics, and overview some ongoing projects within the Argall Research Group.

Tue, Feb 4

Speakers:  Fabrizio Sergi, PhD

Title: Human robotics for gait assistance and clinical neuroscience: two case studies

Host: Dr. Kuiken

Fri, Jan 31

Speakers:  Dr. Chris Marciniak, Dr. Richard Harvey, Kathleen Doherty, and Nathalia Headley

Title: Expert Insights into the IRB

Abstract:   Institutional Review Boards (IRBs) were created to protect people who  volunteer to be in research studies.  The IRB, composed of researchers  and non-scientists, review applications to ensure that the researchers  have designed and planned their studies to minimize patient harms while yielding useful results.  But how does the IRB work and what would be helpful for clinicians and  early career researchers to know about IRB?  The Donnelley Ethics  Program has organized a panel of experienced researchers and IRB members to give you an insight in the workings of an IRB. 

Fri, Jan 24

Speaker: Dr. Milap Sandhu

Title: Intermittent hypoxia and neuroplasticity after spinal cord injury

Abstract:   An important goal of spinal cord injury (SCI) research is to enhance plasticity in the neural pathways spared by the lesion. One experimental strategy for induction of neuroplasticity is brief and repeated exposure to low oxygen, also called “intermittent hypoxia”. Recent studies show that intermittent hypoxia can safely and effectively enhance respiratory and somatic function in both animals and humans after SCI. We are interested in understanding the mechanisms of hypoxia-induced plasticity and developing combinatorial approaches that utilize intermittent hypoxia to improve motor recovery after SCI. I will present data from three different studies which used intermittent hypoxia or related therapies to enhance respiratory function after cervical SCI. First, we studied the impact of intermittent hypoxia on cervical interneurons, which play an important role in the neural circuit remodeling and spontaneous recovery after SCI. Using a multi-array spinal cord recording approach, we show that these interneurons are capable of dynamic reconfiguration during hypoxia.  Similar to respiratory motoneurons, interneurons also showed long term facilitation of activity following intermittent hypoxia. Second, we investigated if a pharmacological agent that activates hypoxia-sensitive carotid chemoafferent neurons can also be used for targeted induction of respiratory neuroplasticity. Our results show that repeated systemic delivery of doxapram, a respiratory stimulant, can trigger robust time-dependent plasticity in the respiratory motor system. In addition, the pattern and magnitude of doxapram-induced facilitation is similar to hypoxia-induced plasticity. Doxapram is an FDA approved drug and may therefore be of use in the context of neurorehabilitation following SCI. Third, we are interested in developing experimental combinatorial approaches using intermittent hypoxia in conjunction with therapies that promote axonal regeneration. To this end, we have shown that hypoxia can modulate the activity of neuronal progenitor cells which have been transplanted into the spinal cord after injury. Furthermore, in related experiments, we have shown that in vitro exposure of neural precursor cells (i.e. partially differentiated stem cells) to intermittent hypoxia can impact their proliferation, survival and differentiation properties. Therefore, intermittent hypoxia may be useful to “prime” donor cells prior to grafting in the spinal cord. In conclusion, plasticity is an important feature of the spared neural pathways after injury, and intermittent hypoxia provides a tool to harness this plasticity and holds promise for use in conjunction with other therapeutic approaches. 

Host: Drs. Jayaraman and Rymer

Fri, Jan 10  **RESCHEDULED from Nov 8

Speaker: Dr. Sean Deeny (from the Rehabilitation Technologies & Outcomes Lab)

Title:  EEG Measures of Cognitive Workload and Cortical Dynamics During Myoelectric Prosthetic Limb Use

Abstract:   A primary goal in development of new myoelectric prosthetic technology is to reduce the cognitive workload or attentional demands of limb control.  Towards that end, the past decade has seen significant advances in prosthetic limb control strategies, prosthetic design, and even surgical techniques, all of which are intended to make prosthesis control as intuitive and functional as possible. However, there are currently no objective and quantitative outcome measures employed in the prosthetics literature to assess cognitive burden of using myoelectric prostheses, or to effectively measure and distinguish the cognitive, perceptual, or motor demands of prosthetic limb use.  We are exploring EEG measures of cortical resource allocation during myoelectric limb control for the purpose of evaluating and guiding new technological advances in “intuitive” prostheses.  We examined the efficacy of event-related potential (ERP) measures of cortical activation as a cognitive workload outcome tool during myoelectric virtual arm control, and compared the cognitive and physical workload of two methods of myoelectric control, direct control (DC) and pattern recognition control (PRC) in sixteen healthy participants with in-tact limbs.  For complicated (3 DOF) movements, PRC was faster and required less muscle activation (EMG), consistent with greater efficiency.  ERP measures of cognitive workload distinguished different levels of difficulty (viewing, 1 DOF, 3 DOF), and distinguished DC from PRC in the 3 DOF condition. We are currently adapting the paradigm to be testing in patients with upper limb and lower limb amputations, and exploring other EEG measures of cortical activation and cortico-cortical communication for future studies.

Host: Dr. Jayaraman   

Fri, Jan 3

Speaker: Dr. Jinsook Roh

Title: Toward muscle coordination-based biological markers for stroke neurorehabilitation

Abstract: How the central nervous system selects which muscles to use from a  mechanically redundant set to complete a motor task is one of the major  unresolved questions in Motor Neuroscience. It is central to understanding both normal  movement and its disruption in neurological disorders. The resulting  scientific knowledge can provide insights on the physiological changes  occurring after neurological injury and form a foundation for innovative translation to develop effective outcome measures in  neuromodulation and neurorehabilitation. Understanding the differences  between normal and pathological neuromuscular coordination schemes can  be utilized to design novel biofeedback of rehabilitative interventions to restore motor functions in stroke survivors. I will  discuss scientific findings on the neural mechanisms of muscle  coordination in animal models and their translation to quantify  abnormalities in muscular coordination in stroke survivors.  

Host: Dr. Rymer