Workspace location influences joint coordination during reaching in post-stroke hemiparesis

Area of Science:

• Neuroscience
• Biomechanics
• Rehabilitation Science

Background:

• Post-stroke hemiparesis often leads to motor control deficits.
• Understanding joint coordination is crucial for effective stroke rehabilitation.

Purpose of the Study:

• To investigate how workspace location affects joint coordination in individuals with post-stroke hemiparesis.
• To determine the influence of trunk motion on reaching movements beyond functional arm length.

Main Methods:

• Utilized the uncontrolled manifold approach to partition joint variance during reaching tasks.
• Measured joint motions, hand movement characteristics, and trunk movement in hemiparetic and control subjects.
• Analyzed variability in joint combinations controlling hand path and position relative to the trunk.

Main Results:

• Hemiparetic subjects showed significantly greater non-equivalent joint variability when reaching ipsilaterally compared to controls.
• This increased variability was related to hand path and position control relative to the trunk.
• Altered relative timing between hand and trunk movements was observed during ipsilateral reaches in hemiparetic individuals.

Conclusions:

• Findings suggest a deficiency in the "arm compensatory synergy" in individuals with hemiparesis.
• Potential causes include altered central commands, limited shoulder-elbow coordination, or reduced degrees-of-freedom for trunk compensation.
• These deficits may hinder effective reaching movements, especially towards the affected side.