Research in the Motor Control Laboratory focuses on motor coordination across the lifespan and in neurological populations. Theoretical approaches are combined with clinical applications to advance our understanding of the mechanisms underlying sensorimotor control of human movement as well as provide the basis for rehabilitative interventions. The lab is equipped with an electromagnetic 3-D motion analysis system, force plate, instrumented manipulanda, surface EMG systems, an eye movement system, and a variety of clinical assessment tools. Research opportunities are available for post-doctoral, doctoral and masters students as well as undergraduate students. Current research includes collaborations with Physical Medicine and Rehabilitation and Internal Medicine.
Contact Information:
Director: Susan Brown, Ph.D.
Telephone: (734) 763-6755
Email: shcb@umich.edu
| Upper Limb Function in Pediatric Motor Disorder Conditions |
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a. Effectiveness of Upper Limb Training in Hemiparetic Cerebral Palsy
In collaboration with Dr. Edward Hurvitz, Dept.of Physical Medicine and Rehabilitation (link), we have been investigating the effectiveness of a home-based upper limb training program in improving motor function in children with spastic hemiparesis. In contrast to constraint-induced training protocols, our six-week regimens involve a traditional (30 min, three times a week) or intensive (30 min, twice daily, five days a week) program in which student trainers work with the child in either a home or school setting. Using programs designed by an occupational therapist, the child is encouraged to perform task-oriented movements using the affected arm and hand. Laboratory-based, quantitative assessments of upper limb function are performed prior to training, and at three, six, and nine weeks post baseline. Preliminary results indicate that intensive training (as described above) can lead to improved control of arm trajectory during forward reaching by as early as three weeks. A more traditional approach may also improve trajectory control but appears to take up to six weeks before improvement is seen.
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(funded by the National Institute on Disability and Rehabilitation Research) |
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b. Bilateral Sensorimotor Coordination in Children with Hemiparetic Cerebral Palsy
In neurological conditions where one limb is more impaired than the other, rehabilitation typically focuses on the affected limb to the exclusion of the other less or unaffected limb. However, there are both theoretical and neurophysiological arguments to suggest that the use of bilateral tasks may actually improve limb function in conditions characterized by unilateral learned disuse. Our understanding of the problems specific to bilateral limb control in asymmetric conditions such as cerebral palsy, is remarkably poor. Further, it is not known whether proprioceptive impairment may contribute to the motor deficits observed in this population and how these impairments correlate with each other. Proprioceptive ability is quantified using an upper limb matching paradigm and forward reaching unilateral and bilateral movements are analyzed in 3-D space. |
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c. Upper Limb Function in Congenital Brachial Plexus Palsy
Congenital brachial plexus palsy (CBPP) arises from injury to the brachial plexus as a result of compression or traction of the anterior shoulder during delivery. While recovery occurs in most individuals, muscle weakness may persist to varying degrees. Typically, this condition presents as an asymmetric motor deficit with only one arm being affected. From a motor control perspective, very little is known how this condition impacts motor coordination – does muscle weakness manifest itself through simply motor slowing or are there also deficits in, for example, multijoint coordination, particularly during bimanual tasks? Will bilateral movement facilitate unilateral impairment which might, in turn, be an effective rehabilitative technique in this population? In addition to examining motor performance in CBPP, we are also examining proprioceptive ability in order to determine whether a long-term reduction in limb usage due to muscle weakness impacts not only motor output but utilization of sensory feedback as well.
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(Funded by UM Mott Children’s Hospital) |
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| The Effects of Aging on Upper Limb Function |
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a. Hand Force Coordination in the Elderly
These studies examine the coordination of bimanual force production during prehension and power grip tasks in young and elderly subjects. Developmental issues concerning unilateral versus bilateral maximum force production, as well as the coordination of simultaneous pinch and power grip during bimanual tasks, form the basis for these studies |
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b. Age-Related Changes in Limb-Posture Coordination
Older adults are more likely to experience loss of balances due to age-related changes in the cognitive, sensory, and motor systems. One way to maintain balance during daily activities is to make anticipatory postural adjustments (APA) prior to the occurrence of postural perturbations. We are currently investigating APA in young and older adults during reaching tasks made from the standing position. In young adults, the organization of APA is influenced by the expected magnitude and direction of the perturbation and the side of limbs used to carry out the motor action. The goal of this research is to find out whether or not older adults can adapt their APA in response to changes in these task demands. |
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c. Age-Related Changes in Upper Limb Proprioceptive Acuity
Changes in motor function as a result of the aging process are well documented yet our understanding of proprioceptive deficits are remarkably poor. Most studies examining age-related sensory loss have focused on the lower limb despite the importance of upper limb function in many activities of daily living. This project examines changes in upper limb proprioceptive acuity in older adults using a position matching paradigm in which the need for proprioceptive memory and interhemispheric transfer of proprioceptive feedback can be manipulated. In addition, the effects of general physical activity levels on proprioceptive acuity will also be examined. (Funded by UM- Elizabeth Crosby Research Award) |
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d. Sensory Facilitation of Upper Limb Movements in the Elderly and in Parkinson’s Disease
Slowness of voluntary movement coupled with impaired control of movement sequences characterize degenerative neurological disorders such as Parkinson’s Disease and may compromise functional activities in older, but otherwise healthy, individuals. Sensory facilitation of locomotor function has been documented in a variety of disease conditions but little research has been conducted on upper limb control. This study examines the effectiveness of sensory cueing on upper limb coordination and balance control in healthy elderly individuals and persons with Parkinson’s Disease. Auditory stimuli are used as external timing cues for rhythmic reach and grasp movements made from a standing position. Postural stability (center of pressure), arm trajectory (3-D kinematics) and grasp control (force production) are analyzed with a particular emphasis on the temporal coordination of trunk, arm, and hand movement. Preliminary results indicate that auditory cueing of repetitive arm reaching movements made from standing improves motor coordination in PD. Thus, sensory pacing of motor tasks may be an effective means of maintaining or even improving functional ability in individuals with chronic movement disorder conditions. (Supported by the NAI Institute on Ageing) |
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| The role of handedness in proprioceptive acuity |
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It is thought that proprioceptive feedback related to limb position is enhanced during active versus passive displacement, presumably as a result of the increased fusimotor drive in goal-directed movement. To what extent this phenomenon may be affected by hemispheric asymmetries has not been examined despite recent suggestions that control strategies differ for the dominant and nondominant arms (Sainburg, 2002). The purpose of this study is to determine the effects of limb dominance on proprioceptive acuity during matching tasks where reference movements are either passively or actively generated. A variety of proprioceptive matching tasks which vary in terms of perceptual motor difficulty are utilized and, thus far, a dominance effect has been seen for tasks that require matching a remembered limb position with the contralateral arm. This effect is only seen during passive movements, however, as in active matching no differences in error have been observed between the two forearms. These results suggest that limb position feedback may be utilized differently by the two hemispheres in passive conditions where spindle sensitivity is minimal and/or in conditions where no efferent copy of a motor command is generated. |
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Motor Control Lab Members
Back Row (left to right): Dann Goble, Colleen Lewis, Dr. Susan Brown, Megan Penfold, Min Huang, Diane Adamo, Brian Marian.
Front Row (left to right): Amber Rho, Corinne Kistka, Jineane Shibuya. |
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Faculty:
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Susan
Brown, Ph.D. (shcb@umich.edu),
Director |
| Post-Doctoral Fellow: |
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Colleen Lewis, Ph.D. (caelewis@umich.edu) |
| Doctoral Students: |
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Diane Adamo, M.S.O.T. (adamo@umich.edu) |
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Gerry Conti, M.S.O.T. (gconti@umich.edu) |
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Dann Goble, M.H.K. (dgoble@umich.edu) |
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Min Huang, M.A. Ed.M. (mhhuang@umich.edu) |
| Research
Assistant: |
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Nichole
Samczyk, B.S. (nsamczyk@umich.edu) |
| Undergraduate
Students (2004): |
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Jason Chesney, Movement Science |
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Corinne Cistka, Psychology |
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Jodi Kirsch, Movement Science |
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Brian Marian, Movement Science |
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Megan Penfold, Movement Science |
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Amber Rho, Movement Science |
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Jineane Shibuya, Movement Science |
| Collaborators: |
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Edward Hurvitz, M.D. (ehurvitz@umich.edu), UM Dept. of Physical Medicine and Rehabilitation |
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Neil Alexander, M.D. (nalexand@umich.edu), UM Geriatrics Center, CCGCB |
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