Exploiting evolutionarily conserved pathways to promote plasticity of human spinal circuits

Area of Science:

• Neuroscience, Rehabilitation Science, Locomotion Studies

Background:

• Humans retain evolutionary traits from quadrupedal ancestors, influencing neural pathways.
• The central nervous system exhibits neuroplasticity, allowing activity to alter its function.
• Spinal cord excitability, measurable via reflexes, is a key indicator of neuroplasticity.

Purpose of the Study:

• To review conserved pathways in human locomotion and their role in rhythmic movement.
• To experimentally investigate exploiting conserved pathways for bidirectional spinal cord excitability modulation.

Main Methods:

• Review of human quadrupedal locomotion characteristics and cutaneous input integration.
• Experimental modulation of spinal cord excitability using patterned cutaneous stimulation.
• Exploitation of cervicolumbar connections to enhance rhythmic movement-induced plasticity.
• Investigating interactions between rhythmic movement, fatigue, and cutaneous stimulation.

Main Results:

• Patterned cutaneous stimulation increased spinal cord excitability.
• Cutaneous afferent stimulation amplified voluntary plantar and dorsiflexion.
• Rhythmic movement and fatigue decreased spinal cord excitability.
• Cutaneous stimulation mitigated excitability reductions caused by fatigue.

Conclusions:

• Cutaneous stimulation increases, while quadrupedal locomotor activity decreases, spinal cord excitability.
• Conserved pathways can be targeted for bidirectional modulation of spinal cord excitability.
• Findings provide insights for rehabilitation and sport performance enhancement.