Optimization and variability of motor behavior in multifinger tasks: what variables does the brain use?

Area of Science:

• Neuroscience
• Motor Control
• Biomechanics

Background:

• Neural control of movement can be conceptualized using different elemental variables.
• Key elemental variables for finger pressing tasks include individual finger forces and central motor commands (finger modes).

Purpose of the Study:

• To determine which set of elemental variables (finger forces vs. central commands) is utilized for optimizing finger force sharing.
• To identify which set of elemental variables is employed for stabilizing motor performance during finger pressing tasks.

Main Methods:

• Employed analytical inverse optimization (ANIO) to assess optimization aspects.
• Utilized uncontrolled manifold (UCM) analysis to evaluate performance stabilization.
• Compared the efficacy of individual finger forces and central commands using these techniques.

Main Results:

• UCM analysis indicated that central commands are favored for performance stabilization.
• ANIO demonstrated comparable effectiveness for both finger forces and central commands in optimization.
• Suggests a neural control scheme where a cost function based on finger forces is transformed into one optimized in the space of central commands.

Conclusions:

• Central commands are likely used by the central nervous system (CNS) for stabilizing finger pressing tasks.
• The CNS may optimize performance by substituting a finger-force-based cost function with a more computationally convenient central-command-based one for feedforward control.