Influence of Contralesional Cortex on Muscle Activity Patterns During a Pedaling Task Post-Stroke

Project: Research project

Project Details

Description

Stroke is a leading cause of disability in the United States, with most stroke survivors experiencing lasting locomotor deficits. One category of deficit is muscle phasing; muscles of the paretic limb are active during inappropriate phases of the locomotor cycle. This inappropriate phasing varies significantly depending on the activity of the non-paretic limb, even when the limbs are mechanically isolated and the task of the paretic limb held constant. Prior research has shown that control of force required from the non-paretic limb, rather than its afferent feedback, is responsible for inappropriate phasing of muscle activity of the paretic limb, with greater nonparetic limb activity resulting in increasingly inappropriate paretic muscle activity phasing. This suggests that increased descending drive of the contralateral limb is responsible in part for interfering with phasing of muscles in the paretic limb following stroke.
While average muscle activity phasing is inappropriate, in a small percentage of cycles muscle activity is well-phased, suggesting there is potential for rehabilitation of this deficit. I propose providing visual EMG signal feedback to subjects on the phasing of a knee extensor muscle, the vastus medialis (VM). VM plays a critical role in locomotion, and its phase of activation varies significantly between behaviors. Visual feedback has shown promise in varying force profiles in nonimpaired individuals, and I predict that individuals with lower limb hemiplegia post-stroke can also use visual feedback to vary phase. To investigate the role of contralateral interference in this within-task phase shift, I will investigate two-legged versus one-legged pedaling, and predict subjects performing a bilateral task will have greater difficulty achieving phase changes due to interference from activation of the contralateral limb.
Based on this ability to vary phase, I then propose to investigate how robust this phase change is to variation in the task, by asking subjects to achieve a consistent deactivation phase during a variety of speeds. As a result of these proposed studies, I will have determined the ability of the post-stroke nervous system to alter inappropriately phased muscle activity in the context of a locomotor-like task and at a variety of speeds, thus forming a scientifically-based paradigm for exercise intervention to assist people recovering from stroke to enjoy improved function and increased participation in the community.
StatusFinished
Effective start/end date1/1/1412/31/15

Funding

  • American Heart Association Midwest Affiliate (14PRE18870084)

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