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Motor Control Laboratory

Dr. Susan Brown

4100 Observatory Lodge
1402 Washington Heights
Ann Arbor, MI 48109-2013
Phone: (734) 763-5829
Dr. Brown's research web site (leaving Kinesiology site)

Research Overview

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.

More information can be found on Dr. Brown's research web site (leaving Kinesiology site)
Dr. Brown's work with virtual trainers featured on the U-M Health System site.

Contact Information:
Director: Susan Brown, Ph.D.
Telephone: (734) 763-6755
Email: shcb@umich.edu

Current Projects

Upper Limb Function in Pediatric Onset Motor Disorder Conditions

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.
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. (Funded by U-M Mott Children's Hospital)

Effectiveness of Upper Limb Training in Children with Hemipalesic Cerebral Palsy
In collaboration with Dr. Edward Hurvitz, Dept.of Physical Medicine and Rehabilitation, we have recently completed a study investigating the effectiveness of a home-based upper limb training program in improving motor function in children with spastic hemiplegia. Six-week training involved either a traditional (30 min, three times a week) or intensive (30 min, twice daily, five days a week) programs in which student trainers worked one-on-one with the child in either a home or school setting. Using programs designed by an occupational therapist, children were encouraged to perform task-oriented movements using the affected arm and hand both unilaterally and bilaterally. Laboratory-based, quantitative assessments of upper limb function were performed prior to training, and at three, six, and nine weeks post baseline. Results indicate that intensive training (as described above) can lead to improved control of arm trajectory and hand function 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. (funded by the National Institute on Disability and Rehabilitation Research)

For more information, including abstracts and research posters, visit Dr. Brown's research site.

Upper Limb Sensorimotor Training in Adults with Hemiplegic Cerebral Palsy

Cerebral palsy (CP) is viewed as a pediatric disorder despite the fact that the life expectancy in CP is comparable to that of the general population. Although considered a non-progressive condition, many adults with CP experience declines in functional performance beginning as early as late adolescence. An upper limb training and assessment protocol has been developed entitled Project ULTrA for adults with hemiplegic CP. This intervention will involve upper limb reaching, hand grasp function and sensory training components based on principles of neural plasticity. For more information, please visit Dr. Brown's web site. (leaving Kinesiology site). This work is also featured on the U-M Health System site, which has a video

The Effects of Aging on Upper Limb Function

Bilateral Force Coordination in the Elderly
The ability to precisely control force generation during bilateral hand tasks can be particularly challenging for older individuals. These studies examine bilateral force coordination during tasks involving different types of force production (grasp versus pinch) and having different temporal requirements in terms of force onset and offset.
Age-Related Changes in Limb-Posture Coordination
During reaching from a standing position, the central nervous system must maintain trunk stability through anticipatory postural adjustments (APA) which occur prior to limb movement. An impaired ability to produce APAs during reaching can lead to loss of balance and falls, particularly in older individuals. In these studies, we focus on the coordination between center of pressure excursion and arm movement kinematics as a function of age, target location, and limb dominance.

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 grasp force and position matching paradigms 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 U-M-NSF ADVANCE Award, National Institute on Aging)

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.

For more information, including abstracts and research posters, visit Dr. Brown's research web site.

The Role of Proprioception in Handedness

Despite the emphasis that has been placed on feedback utilization in the determination of handedness, most studies on motor laterality have focused on visually-guided movements. Given the number of activities that rely heavily upon previous proprioceptive experience, the extent to which limb asymmetries exist during proprioceptively-guided movements is certainly of importance. Utilizing an elbow position matching paradigm limb asymetries in the utilization of proprioceptive information are being explored under a variety of task conditions including the mode of target presentation (active vs. passive), the need for generation and/or interhemispheric transfer of target position information and the workspace within which matches are made. Thus far, a clear dominance effect has been seen during tasks that require memory-based matching of a target limb position with the contralateral arm. These results suggest that limb position feedback may be utilized differently by the dominant and non-dominant hemispheres.

For more information, including abstracts and research posters, visit Dr. Brown's research web site.

Members

Motor Control Laboratory members: Diane Adamo, Min Huang, Dr. Susan Brown,
Dr. Colleen Lewis. Missing: Gerry Conti, Dann Goble.

Faculty:
    Susan Brown, Ph.D. (shcb@umich.edu), Director
Post-Doctoral Fellow:
    Colleen Lewis, Ph.D. (caelewis@umich.edu)
Doctoral Students:
    Diane Adamo, M.S.O.T. (adamo@umich.edu)
    Gerry Conti, M.S.O.T. (gconti@umich.edu)
    Dann Goble, M.H.K. (dgoble@umich.edu)
    Min Huang, M.A. Ed.M. (mhhuang@umich.edu)
Master's Student:
    Beth Wiggert, B.S., P.T. (bwiggert@umich.edu)
Visiting Scholar:
    Karen Healy, B.S. (khealy@umich.edu)
Undergraduate Students:
    Pooja Bhadbhade
    Alison Clune
    Katie DiCosmo
    Beth Hill
    Stephanie Levy
    Joe McCarthy
    Gabrielle Nguyen
    Allison Parent
    Brian Skvarla
    Christy Waechter
Collaborators:
    Edward Hurvitz, M.D. (ehurvitz@umich.edu), U-M Dept. of Physical Medicine and Rehabilitation
    Neil Alexander, M.D. (nalexand@umich.edu), U-M Geriatrics Center, CCGCB