Selective and Graded Recruitment of Cat Hamstring Muscles With Intrafascicular Stimulation

The muscles of the hamstring group can produce different combinations of hip and knee torque. Thus, the ability to activate the different hamstring muscles selectively is of particular importance in eliciting functional movements such as stance and gait in a person with spinal cord injury. We invest...

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Bibliographic Details
Published in:IEEE transactions on neural systems and rehabilitation engineering 2009-12, Vol.17 (6), p.545-552
Main Authors: Dowden, Brett R., Wilder, Andrew M., Hiatt, Scott D., Normann, Richard A., Brown, Nicholas A. T., Clark, Gregory A.
Format: Article
Language:English
Subjects:
Activated
Activation
Animals
Arrays
Cats
Electric Stimulation - methods
Electrodes
Electromyography
Feline hamstring muscles
Hindlimb - innervation
Hindlimb - physiology
Hip
Instruments
intrafascicular stimulation
Knee
motor neuroprosthesis
Muscle Contraction - physiology
Muscle, Skeletal - innervation
Muscle, Skeletal - physiology
Muscles
Nerves
neuromuscular stimulation
Pulse modulation
Recruitment
Recruitment, Neurophysiological - physiology
Sciatic Nerve - physiology
selective activation
Spinal cord injury
Stimulation
Thresholds
Torque
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Summary:The muscles of the hamstring group can produce different combinations of hip and knee torque. Thus, the ability to activate the different hamstring muscles selectively is of particular importance in eliciting functional movements such as stance and gait in a person with spinal cord injury. We investigated the ability of intrafascicular stimulation of the muscular branch of the sciatic nerve to recruit the feline hamstring muscles in a selective and graded fashion. A Utah Slanted Electrode Array, consisting of 100 penetrating microelectrodes, was implanted into the muscular branch of the sciatic nerve in six cats. Muscle twitches were evoked in the three compartments of biceps femoris (anterior, middle, and posterior), as well as semitendinosus and semimembranosus, using pulse-width modulated constant-voltage pulses. The resultant compound muscle action potentials were recorded using intramuscular fine-wire electrodes. 74% of the electrodes per implant were able to evoke a threshold response in these muscles, and these electrodes were evenly distributed among the instrumented muscles. Of the five muscles instrumented, on average 2.5 could be selectively activated to 90% of maximum EMG, and 3.5 could be selectively activated to 50% of maximum EMG. The muscles were recruited selectively with a mean stimulus dynamic range of 4.14 ± 5.05 dB between threshold and either spillover to another muscle or a plateau in the response. This selective and graded activation afforded by intrafascicular stimulation of the muscular branch of the sciatic nerve suggests that it is a potentially useful stimulation paradigm for eliciting distinct forces in the hamstring muscle group in motor neuroprosthetic applications.
ISSN:1534-4320
1558-0210
DOI:10.1109/TNSRE.2008.2011988