Hindlimb Movement in the Cat Induced by Amplitude-Modulated Stimulation Using Extra-Spinal Electrodes

J Neural Eng, 2008 · DOI: 10.1088/1741-2560/5/2/002 · Published: June 1, 2008

Simple Explanation

This study investigates how electrical stimulation of the spinal cord using electrodes placed outside the spinal column can induce hindlimb movement in cats. The researchers explored how different locations and patterns of stimulation affect the type of movement produced, such as flexion or extension of the hindlimbs. The study also looks at the impact of spinal cord transection on these induced movements, suggesting implications for restoring locomotion after spinal cord injury.

Study Duration

Not specified

Participants

8 cats (2 male and 6 female, 2.8 kg to 4.3 kg)

Evidence Level

Not specified

Key Findings

1
Stimulation location influences movement type: rostral segments (L5) induced flexion, caudal segments (L7/S1) induced extension.
2
Dorsal root stimulation at L7 produced the largest ground reaction force, sufficient to support body weight.
3
Amplitude-modulated stimulation, combined with timed stimulation of different spinal segments, can generate stepping movements.

Research Summary

The study demonstrated that extra-spinal electrical stimulation, particularly when amplitude-modulated, can induce coordinated hindlimb movements in cats, including flexion, extension, and stepping. The location of stimulation along the spinal cord (rostral vs. caudal segments) determined the type of movement induced, and dorsal root stimulation at L7 was particularly effective in generating ground reaction force. Spinal cord transection did not abolish the induced movements, suggesting that the stimulation directly activates spinal locomotor circuits without requiring supraspinal input.

Practical Implications

Restoration of Locomotion

The findings suggest a potential method for restoring locomotor function after spinal cord injury by using extra-spinal electrodes and amplitude-modulated stimulation to activate spinal locomotor circuits.

Clinical Translation

The use of extra-spinal electrodes, already employed clinically, makes the stimulation strategy and techniques developed in this study potentially translatable to human applications for SCI rehabilitation.

Controlled Movement

Amplitude-modulated stimulation allows for controlled adjustment of stepping amplitude and duration, improving upon constant-intensity epidural stimulation methods.

Study Limitations

1
Study conducted under pentobarbital anesthesia, which may influence reflex motor activity.
2
Neural control of locomotion in humans is significantly different from that in cats.
3
Only an open-loop control method using a pre-determined stimulation waveform was employed in this study

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