Wei Wang PhD and Doug Weber PhD University of Pittsburgh
Motor Cortical Representation of Hand Movement and Implications for Neuroprosthetics

Janice Eng PhD PT/OT University of British Columbia

Motor Cortical Representation of Hand Movement and Implications for Neuroprosthetics - Wei Wang PhD University of Pittsburgh
May 8, 2008

This talk will cover two topics.  The first topic is on motor cortical representation of hand position, velocity, and rotation during 3D reaching movement.  Motor cortical representation of hand movement is studied by recording single-neuron activities from the primary motor cortex while non-human primates performed 3D reach tasks in a virtual reality simulator. It is found that multiple movement parameters can be represented simultaneously by a common neuronal population at the motor cortex. Cortical representation of hand position and hand velocity interact with each other linearly, while cortical representation of hand translation and hand rotation interact with each other non-linearly in a gain field fashion. Furthermore, a novel decoding algorithm was developed to extract multiple movement signals from a common neuronal population for controlling prosthetic devices.

The second topic covers recent work in developing a practical brain-computer interface technology. Single-neuron recording has the highest spatial and temporal resolution, but it requires sophisticated recording hardware, and it may lack long-term stability due to tissue encapsulation.  EEG is non-invasive, and it can be recorded with simpler system.  However, its spatial resolution is limited.  Recent work using electrodes implanted in the skull but not penetrating the brain, known as electrocorticography (ECoG), has demonstrated that ECoG can be a powerful technology that combines the merits of both single-neuron recording and EEG.  Hence, it can achieve an optimal balance between the specificity of recorded neural signals and the simplicity of the recording system.  Furthermore, since magnetoencephalography (MEG) signals share similar characteristics as ECoG, MEG can be used as powerful non-invasive methods for conducting "ECoG-type" brain-computer interface studies, as well as for studying human motor physiology.  Preliminary studies have show that a significant modulation of MEG signals during volitional movement was observed for both overt and imagined wrist movement.

First Annual Ann Putnam Kaleckas Lecture:
Movement a System and a Science: Importance to Physical Therapy
Shirley Sahrmann PT PhD FAPTA
April 22, 2008

Several dilemmas have confronted the profession as we have sought to define our body of knowledge and our role in health care. As suggested by the name, physical therapy has its roots in providing treatment for individuals with a lesion in a system of the body, resulting in a focus on rehabilitation or restoration of function of both body segments and of the whole body in performance of activities.  Yet there is growing recognition that the profession should have an active role in guiding the health of individuals without frank lesions.  These dilemmas stem from a question debated for many years.  What is our body of knowledge and what is our relationship to other medical professions?  During the 1970’s and 80’s the primary focus was the patient with central nervous system dysfunction.  The research that most physical therapists pursued was directed at the aberrations in motor behavior in patients with central nervous system dysfunction or in the mechanisms of the nervous system.  

The debate about what constituted the defining body of knowledge of physical therapy finally resulted in identifying movement as the focus of both the practice and the science of the profession.  A publication in 1987 related movement science to the rehabilitation of individuals with central nervous system lesions. Now 20 years later there is ample evidence that movement science is just as important to conditions of the musculoskeletal, cardiopulmonary, and metabolic systems as to the nervous system.  Furthermore, what has not been addressed is the important role the physical therapist should have in guiding the optimal generation of tissues as well as minimizing the effects of degeneration and lesions of body systems.   This role grows out of the fact that MOVEMENT IS A SYSTEM of the body similar to the metabolic system or endocrine system.  Such a role calls for a paradigm shift from practitioners with a short time intense period of patient contact to a birth to death practitioner.  In addition there should be an amalgamation in research and practice of considering all the components of the movement system to avoid an overfocus on just the nervous system or just the musculoskeletal system. A paradigm shift is in order for the delivery of services, for research, and for recognition that movement science covers all components of the movement system, musculoskeletal, neuromotor, cardiopulmonary, and metabolic.  Musculoskeletal conditions have their roots in motor control and neuromotor lesions have major manifestations in musculoskeletal dysfunction.  Physical therapy has a unique role in health care, because we can address the CAUSE of problems not just the manifestation and we can use movement as a treatment and not just as a form of diagnosis. As doctors of Physical Therapy we must move confidently and swiftly to define our expertise and practice patterns so that they parallel those of others with responsibility for the care of a system of the body.

This lecture will discuss the reasons and directions for a paradigm shift and discuss the evidence to support the rationale.

Local Neuro-mechanical Factors for Progression of Knee Osteoarthritis - Allison Chang PT DPT Northwestern University
April 3, 2008

Current Concepts in Articular Cartilage Repair & Rehabilitation - David R. Guelich MD, Chicago Orthopedics & Sports Medicine
March 13, 2008

What is articular cartilage? Macroanatomy, Microanatomy, Biology of cartilage healing
Articular Cartilage Injury: Osteochondritis Dessicans, Traumatic­associated lesions? Natural history­should we treat articular cartilage injuries?
Historical Treatments: Lavage, Chondroplasty, Abrasion chondroplasty
Modern Treatments: Microfracture, OATS­osteochondral autografts, Allograft OATS, ACI­autologous chondrocyte implantation
Rehabilitation of Cartilage Treatments:
Tailoring postoperative rehabilitation programs, What are the patient factors? How are associated injuries factored?
Principles of rehabilitation of cartilage repair: Knee (Weight bearing, Motion, Location of repair), Shoulder, Ankle
What is the future?

Susanna Calkins PhD Assoc. Director Searle Center for Teaching Excellence, Northwestern University
February 21, 2008

Jaques Duysens MD., PhD Chair in Motor Control, Catholic University Leuven, Belgium
February 5, 2008

Ellis Nam MD, Chicago Orthopedics and Sports Medicine
November 15, 2007

Nora Francis PT OTR DHS, Assistant Professor, DPTHMSNovember 8, 2007
November 8, 2007

Jennifer Brach PT PhD, Assistant Professor, University of Pittsburgh
October 11, 2007

Deydre S. Teyhen PT PhD OCS, Assistant Professor, Baylor University
September 27, 2007

Total Hip Replacement: Why We Need It and How We Can Do It Right - Fang (Amanda) Lin, DSc, Department of Physical Therapy and Human Movement Sciences, Northwestern University
September 13, 2007

Biomechatronic Engineering in Stroke Rehabilitation - Arno Stienen, MSc, University of Twente, Enschede, The Netherlands
August 20, 2007

According to recent publications, training with upper-extremity rehabilitation robotic devices is equivalent if not better than routine stroke rehabilitation, probably because the robotics increase the training intensity for the patients. Several components may affect the therapy outcome in upper-extremity rehabilitation robotics. A common component is gravity compensation, which facilitates upper-extremity movements. Gravity compensation by itself could improve motor control further or faster, separate from other effects of robotic therapy. To isolate the rehabilitation value of gravity compensation, we created the dedicated gravity compensation system, the Freebal. It is a simple, lightweight, and purely mechanical device using ideal-spring mechanisms, capable of providing constant gravity compensation in a roughly 1 m^3 volume. We have used the Freebal to investigate what happens in acute stroke patients when we fully compensate for their arm strength against the gravitational pull, what are the changes in movement and EMG patterns and how is this linked to new research by other scientists who achieve positive results when only using gravity compensation in training. As an alternative to the functional approach of mimicking activities of daily living, targeted force-coordination training may also have its benefits. Our passive exoskeleton, the Dampace, is designed to combine the functional training of activities of daily living with force-coordination training. It has controlled braking on the three rotational axes of the shoulder and one on the elbow. To overcome some of the difficulties traditionally associated with exoskeletons, the Dampace axes do not need to be aligned to the human shoulder and elbow axes. Although it adds more complexity, the reduction of setup times to just a few minutes, along with the absence of static reaction forces in the human joints, are major advantages and have been well received by therapists and physicians. Controlled braking instead of actively assisting actuators, has the advantage of inherent safety and patients always actively participating, at the cost of not being able to assist movements or create all virtual environments. So where does this leave us?

The Role of the Cortex in the Loss of Independent Joint Control Following Stroke - Jun Yao PhD Research Assistant Professor in the Department of Physical Therapy and Human Movement Sciences
April 26, 2007

The role of the cortex in the expression of discoordination, defined as a loss of independent joint control following stroke, was quantified by simultaneously recording 163-channel EEG together with elbow/shoulder torques and EMGs from the paretic upper limb. The novel combination of imaging and mechanical measurements provides the first evidence not only of a significantly greater overlap between activity in sensorimotor cortices (SMC) related to the elbow versus shoulder tasks in hemiparetic stroke as compared to able-bodied subjects but also of a linear relationship between the overlap and obligatory shoulder/elbow coupling. The result of this study points to a distinct loss in cortical resolution following stroke resulting in an increased overlap in SMC activity related to the execution of isometric shoulder and elbow tasks, thus leading to a reduction in the independent joint control commonly observed following stroke.

Outcomes of Upper limb training and Botulinum toxin A across the Int'l Classification of Function (ICF) - Rosalyn Boyd PT PhD Associate Professor, LaTrobe University School of Physiotherapy Murdoch Children's Research Institute, Victoria, Australia
March 8, 2007

This seminar would discuss the recently completed RCT that investigated the effects of Upper limb training with and without intramuscular injections of BTX-A incorporating functional MRI, measures of muscle stiffness with torque motors, measures or activity limitation, participation and health related quality of life. Dr. Boyd will also address the limitations of various tools and the new directions that outcome measurement in CP is taking with new tools measuring Participation and HRQOL.

Complexity of Cortical Sensorimotor Atrophy and Plasticity following Cervical Spinal Cord Injury: Implications for Recovery and Rehabilitation - Molly Verrier, M.H.Sc., Dip(P&OT) Associate Professor, University of Toronto
February 1, 2007

Optimal hand function in patients with tetraplegia is reported to be one of the most important indicators for Quality of Life. Therefore understanding how to evaluate and optimize recovery of hand function post injury is of import to rehabilitation scientists. However, the determinants of both neurological (sensorimotor) and functional (activity) recovery in tetraplegia remain largely unexplored. Precise and meaningful measurements of recovery are difficult due to lack of sensitive and standardized assessment protocols that capture change in both sensorimotor function and function ability. Likewise the variability in the extent, location and degree of completeness of injury make interpretation of findings problematic. Animal studies of complete spinal cord transection have demonstrated atrophy in both the motor system (rubro- and cortico-spinal neurons) and in the sub-cortical sensory system (cuneate nuclei and thalamus). Using voxel-based morphometry we compared grey matter volumes in a cross sectional group of spinal-cord injured (SCI) persons (n=18) with “complete” cervical SCI (mean time post injury = 51 [range 1-160] months) resulting in tetraparesis (mean overall ASIA motor score = 19/50; overall sensory score = 24/56) and a group of seventeen age-matched controls to determine if there is cortical atrophy in humans. In contrast to animal studies, there was no evidence of atrophy in primary motor (M1) hand areas in this chronic population. However, medial thalamus and extensive primary sensory (S1) areas demonstrated atrophy in our SCI group compared to the controls. These findings imply that atrophy may be predominantly caused by a lack of overall neuronal input to the region. Accordingly, a de-efferented M1 may continue to get input from higher motor areas, whereas a de-afferented S1 directly loses input resulting in a measurable level of atrophy which have over time post injury have consequences for recovery.

To gain insight into the recovery process we examined cortical sensory and motor representations for voluntary movements to determine extent and location of movement-related cortical activation using functional MRI. Seven tetraplegics and two controls were studied longitudinally up to one year using motor tasks consisting of wrist (at the level of injury) and foot (below the level of injury) movements. Recovery was assessed using the ASIA motor sub-scores related to the level of the injury. In the SCI subjects, initially impaired wrist movements recovered such that by the final study session, movements were performed without observable impairments. During impaired movements, little task-related activation within primary motor cortex (M1) was present while higher-order sensorimotor cortical activation was extensive. During recovery, M1 activation increased and higher-order activation decreased such that, by the final study session, the overall pattern was similar to that of controls. If movement did not recover however, a progressive decrease towards no activation was observed across all sensorimotor areas.

Precise monitoring and understanding of the cortical contributions to movement during recovery could prove useful for improving the application, timing  and evaluation of therapeutic interventions targeted at promoting increased hand function. Studies are underway in the lab to apply therapeutic FES to enhance sensory input and to validate measures and that will capture subtle changes in hand function temporally to determine efficacy of these approaches.

Colum MacKinnon, PhD (PHTMS Grand Rounds)
January 18, 2007

Modern total joint replacements of the hip and knee have emerged as one of the most successful and beneficial surgical procedures of our time. Beginning in the late 1960's, total hip and knee replacements were developed to address arthritis of the hip and knee that previously could not be treated and was a common cause of disability. Failure to correctly position an acetabular cup can result in dislocation of the hip or impingement resulting in component damage and potentially early failure. In total knee replacement, proper positioning of the implants is necessary to restore neutral mechanical alignment of the limb, balancing of the ligaments around the knee for stability and achievement normal range of motion with complete extension and a functional range of knee flexion. For the past three decades total hip and knee implants have been placed relying on mechanical guides to estimate the correct position in surgery.

Evolving from stereo tactic neurosurgical procedures, computer assisted surgical procedures have been developed for both the hip and knee. For hip and knee replacement, computer assisted navigation results in significantly more accurate and reproducible placement of the implants. The benefit of this is a much decreased likelihood of premature total joint failure though dislocation, malalignment, loosening and wear.

This presentation will discuss the rational for these devices, how computer assisted total joint replacement is performed and our early results.