October 30, 2003

Exploring interactions of brain and body

Assistant professor Jules Dewald and research associate Jun Yao are linking brain activity sites in the motor cortex to the specific muscle groups they stimulate.

photos by Jim Ziv

By Elizabeth Crown

Most people would agree that trying to make individuals fall, asking others to pedal a bicycle while lying down and hurling a test participant forward in a sled moving at a speed of 2 Gs constitute a novel approach to physical therapy.

Yet, these seemingly unconventional projects at the Feinberg School of Medicine are providing basic and clinical scientists in the department of physical therapy and human movement sciences new insights into the interactions of the brain and the body.

Associate professor Mark Rogers (left) and department chair John Brooke discuss research as Rogers sets up a balance-perturbing experiment in his motion analysis lab.

Northwestern’s physical therapy researchers, often in collaboration with scientists from diverse fields of study on both campuses, focus on decoding the brain’s connection to physical disabilities and developing new methods of treating patients with stroke and brain injuries, motor coordination disorders and other neurological conditions, such as Parkinson’s disease, that affect balance, gait and other essential, everyday tasks.

Knowledge derived from these studies is rapidly altering the face of physical therapy clinical practice, as well as expanding the breadth and depth of the department’s renowned 75-year-old professional education program — consistently rated among the nation’s top 10 such programs by the U.S. News & World Report’s “Best Graduate Schools” annual survey. In turn, Northwestern students pursuing a doctor of physical therapy degree are required to complete a two-year “synthesis project” with one of the department’s basic or clinical science faculty — all 23 of whom conduct research — thus keeping the physical therapy graduate education program as dynamic and cutting-edge as the department’s research enterprise.

“We’re working hard to educate the very best entry-level physical therapists and to uncover through research the most important concepts about physical therapy practice and its underlying mechanisms,” said John Brooke, professor and chairman of the department.

“Our educational program, which is to a clinical doctor of physical therapy (D.P.T.) degree, emphasizes evidence-based practice in physical therapy. Those entering the profession today must be able to appraise research and judge whether to add a technique to clinical practice based on peer-reviewed, published evidence,” he said.

Brooke, who was named chair in 2000, is a distinguished educator and researcher who studies the control of body proprioception and ergonomics. Proprioception is the ability to sense the position, location, orientation and movement of the body and its parts. Ergonomics is the application of scientific information — anatomy, physiology, and psychology – to design of objects, systems and environments for human use.

Like Brooke’s work, research throughout the department is decidedly multidisciplinary in its scope. During a visit to the department’s laboratories on the 11th floor of the 645 North Michigan building, it’s not unusual to see physical therapy faculty and staff functioning as computer experts, physiologists, neuroscientists, research engineers and clinicians. In addition, many members of the physical therapy faculty have secondary appointments in neurology, physical medicine and rehabilitation, otolaryngology and biomedical engineering.

“Successful treatment requires an expansive view of the patient’s needs as well as an understanding of vital biomedical, psychological and societal mechanisms,” Brooke said.

“For years physical therapists have moved limbs and asked patients to move limbs, expecting rehabilitation. But the brain and the central nervous system’s roles in this have not been adequately explored. The adult brain is very plastic. Research has shown that therapeutic manipulations alter the connections in the brain. With one or two exceptions, we don’t understand how that translates into physical therapy practice. But in 10 years’ time, we will,” he said.

Brooke explained that in researching the biomedical rehabilitation of damaged tissues, it is clear that wide-ranging mechanisms are at play. For example, what happens in movement rehabilitation at the ankle results also in changes in the brain, and these brain changes can be imaged. Further, when the brain can be led to change, and imaging reveals the change, recovery from movement disorder can be facilitated.

Mark Rogers, associate professor and an expert on postural instability and falls in the elderly, is a proponent of the department’s multidisciplinary approach.

“This interface of brain control, biomechanics and behavior is applied to investigating interactions among what have traditionally been looked at as separate systems. We need to understand how individual systems interact as a total movement system and quantify their parameters in a meaningful way,” Rogers said.

Rogers, who has a secondary appointment in physical medicine and rehabilitation, uses a computer-controlled robotic waist-puller device and signal transducers to study the mechanics of falling. The data fed from infrared cameras and ground force plates into the computer provide Rogers and his laboratory group a wealth of information on how and why people fall, why they fall more as they age and how they attempt to protect themselves, or adjust their posture, from falling.

Facilitating recovery from stroke-induced movement disorders is one of the department’s primary research focuses. The effects of stroke vary, based on the type of stroke and its severity and location in the brain. The majority of strokes affect one of the brain’s hemispheres, resulting in muscle weakness or paralysis on the opposite side of the body.

Assistant Professor Jules Dewald uses a variety of techniques to study and treat post-stroke upper-limb movement abnormalities — including functional magnetic resonance imaging and high-resolution electroencephalography — to evaluate how the brain reorganizes itself so that some arm movements unfortunately become difficult to perform and to test new training strategies to overcome such disorders. Dewald has a secondary appointment in physical medicine and rehabilitation and collaborates with researchers in biomedical engineering,

At a research open house earlier this year, David Brown discusses the device he developed to study the effects of stroke on locomotive patterns of muscle activation.

David Brown, assistant professor, focuses on functional impairments, particularly in the mechanisms that control walking, in patients with stroke and brain injury. One of his projects uses a bicycle ergometer, which he helped design, to study how a stroke patient’s impaired nervous system processes loading signals for locomotion. Stroke patients lie on a rotating bench on which is mounted a bicycle-like apparatus. By rotating the bench incrementally during rehabilitation to increase the weight borne by the patient, and using electrodes to stimulate nerves and to measure leg muscle activity, Brown and his co-researchers can evaluate the extent of the response to body-weight loading of the stroke patient’s muscles and central nervous system.

Assistant Professor Colum D. MacKinnon, who has a secondary appointment in the department of neurology, is investigating brain patterns of motor function activity, especially in patients with neurological disorders such as Parkinson’s disease and dystonia.

MacKinnon uses a number of cutting-edge imaging and brain-monitoring techniques to examine the role of the primary and supplementary motor areas and the brainstem in timing and selection of muscle activity during voluntary movement.

With colleagues in the Parkinson’s Disease and Movement Disorders Center at Northwestern, as well as two other medical schools in Chicago, MacKinnon is evaluating the effect of deep-brain stimulation, a neurosurgical intervention, as a treatment of movement and posture abnormalities in advanced Parkinson’s disease.

Faculty members (from left) Dudley Childress, James Webster and Bruce Turpin talk research with Tim Hain (seated).

Timothy Hain, M.D., professor of physical therapy, neurology and otolaryngology, is an expert on dizziness and balance disorders caused by problems in the inner ear and on head-neck postural control in whiplash. With researchers from both campuses, Hain studies how people with vestibular disorders use their other senses to compensate and regain their balance. To study the neurophysiological effects of whiplash, Hain uses a computer-controlled, high-acceleration sled to accurately and safely induce head-neck perturbations.

The department’s other two research “clusters” consist of clinical research, led by Antoinette P. Sander, assistant clinical professor, and professional education research, headed by Karen W. Hayes, associate professor and director of professional education.

Among the clinical research projects currently under way are studies of lymphedema following breast cancer surgery, rehabilitation of ligament damage, electrical stimulation of muscles and cardiac monitoring in exercising heart transplant patients.

Research in the professional education cluster is aimed at improving communication skills between instructors and students as well as clinicians and patients, enhancing curricula and increasing enrollment of underrepresented minority applicants.

The department’s profile is further enhanced by a new relationship with the physical therapy section of rehabilitation services at Northwestern Memorial Hospital. The two entities are exchanging services and increasing interaction in course lectures, laboratories, clinical experiences and faculty practice at the hospital.

This complements a similar relationship the department has with physical therapy services in the Rehabilitation Institute of Chicago.