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Weak motor cortex contribution to the quadriceps activity during human walking
Caroline Iglesias1, George Lourenco, Véronique Marchand-Pauvert
1UPMC Univ Paris 06, ER 6, F-75005, Paris, France.
Gait & Posture
|November 25, 2011
Summary
Human walking involves complex motor control. This study found reduced cortical influence on knee extensor muscles during walking compared to standing, suggesting a lesser role for the motor cortex in knee movement during locomotion.
Area of Science:
- Neuroscience
- Human Locomotion
- Motor Control
Background:
- The precise contribution of cortical and sub-cortical pathways to human locomotion remains incompletely understood.
- While the motor cortex influences ankle muscles during walking, its role in knee extensor activity is less clear.
Purpose of the Study:
- To investigate the modulation of cortical excitability in the Vastus Lateralis (VL) muscle during treadmill walking.
- To compare the cortical contribution to VL activity during walking versus tonic contraction while standing.
Main Methods:
- Transcranial magnetic stimulation (TMS) was employed during treadmill walking at 3-4 km/h.
- Sub-threshold and paired-pulse TMS techniques were used to assess cortical excitability, intra-cortical inhibition, and H-reflex modulation in the VL muscle.
Main Results:
- Sub-threshold TMS effects on VL EMG activity were significantly depressed during walking compared to standing.
- Paired-pulse TMS revealed no change in intra-cortical inhibition during walking, and sub-threshold TMS did not alter the VL H-reflex.
- Cortical pathways mediating short intra-cortical inhibition and facilitation in the VL motor area showed depressed excitability during walking.
Conclusions:
- The excitability of specific cortical pathways influencing the Vastus Lateralis is significantly reduced during walking.
- These findings suggest a lesser cortical contribution to knee extensor muscle activity during human locomotion compared to ankle muscles.
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