Obstacle stepping involves spinal anticipatory activity associated with quadrupedal limb coordination

Area of Science:

• Neuroscience
• Locomotion Biomechanics
• Motor Control

Background:

• Spinal reflexes in leg muscles facilitate obstacle avoidance during walking.
• The role of arm muscles in obstacle avoidance reflexes is less understood.

Purpose of the Study:

• To investigate the involvement of both leg and arm muscles in obstacle avoidance.
• To examine anticipatory changes in spinal reflexes during obstacle avoidance tasks.

Main Methods:

• Subjects walked on a treadmill with reduced vision and received acoustic cues for obstacle avoidance.
• Tibial nerve stimulation was used to evoke reflex responses in leg and arm muscles.
• Electromyographic activity was recorded to assess muscle activation patterns.

Main Results:

• Reflex responses in all examined arm and leg muscles were enhanced before obstacle avoidance.
• Contralateral arm flexor muscles showed exponential adaptation correlating with task performance improvement.
• Arm muscle electromyographic activity mirrored reflex enhancements and adaptations during obstacle steps.

Conclusions:

• Anticipatory quadrupedal limb coordination, involving proximal arm muscles, is crucial for acquiring and performing obstacle avoidance.
• Up-regulated activity in cervico-thoracic interneuronal circuits likely underlies this coordinated motor response.