Passive responses in mouse hind leg locomotion

Area of Science:

• Biomechanics
• Locomotion
• Mammalian Physiology

Background:

• Mouse size suggests passive forces play a role in leg movement.
• Understanding passive forces is crucial for modeling mouse locomotion.

Purpose of the Study:

• To investigate the role and magnitude of passive forces in mouse hind leg movements.
• To determine if passive forces influence joint angles during locomotion.

Main Methods:

• Anesthetized mice hind leg passive movements were measured.
• Responses to changes in gravity orientation and manual leg deflections were recorded.

Main Results:

• Passive responses limit joint rotation range and are present at locomotory joint angles.
• Legs returned to intermediate postures upon release from deflection, indicating passive forces can move the limb.
• Passive response amplitude scaled linearly with deflection, with consistent slopes across joints.

Conclusions:

• Passive forces are significant during mouse locomotion, potentially affecting joint angles.
• The amplitude and direction of passive forces may vary individually, impacting movement patterns.