Electrical Activation of Spinal Neural Circuits: Application to Motor-System Neural Prostheses

Grill, Warren M.

doi:10.1046/j.1525-1403.2000.00097.x

Cited by 13 publications

(8 citation statements)

References 70 publications

(110 reference statements)

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“…The characteristics of these responses differed from those obtained by direct muscle activation-either via intramuscular stimulation or by intraspinal stimulation in the deep ventral horn. These results support the concept that electrical activation of spinal neural circuits by intraspinal stimulation may simplify the artificial control of multi-joint motor function (Barbeau et al 1999;Grill 2000).…”

Section: Implications For Artificial Control Of Motor Functionsupporting

confidence: 83%

Modularity of Motor Output Evoked By Intraspinal Microstimulation in Cats

Lemay

Grill

2004

Journal of Neurophysiology

110

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We studied the forces produced at the cat's hindpaw by microstimulation of the ipsi- and contralateral lumbar spinal cord in spinal intact alpha-chloralose anesthetized (n = 3) or decerebrate (n = 3) animals. Isometric force and EMG responses were measured at 9-12 limb configurations, with the paw attached to a force transducer and with the hip and femur fixed. The active forces elicited at different limb configurations were summarized as force fields representing the sagittal plane component of the forces produced at the paw throughout the workspace. The forces varied in amplitude over time but the orientations were stable, and the pattern of an active force field was invariant through time. The active force fields divided into four distinct types, and a few of the fields showed convergence to an equilibrium point. The fields were generally produced by coactivation of the hindlimb muscles. In addition, some of the fields were consistent with known spinal reflexes and the stimulation sites producing them were in laminae where the interneurons associated with those reflexes are known to be located. Muscle activation produced by intraspinal stimulation, as assessed by intramuscular EMG activity, was modified with limb configuration, suggesting that the responses were not fixed, but were modified by position-dependent sensory feedback. The force responses may represent basic outputs of the spinal circuitry and may be related to similar spinal primitives found in the frog and rat.

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Section: Implications For Artificial Control Of Motor Functionsupporting

confidence: 83%

Modularity of Motor Output Evoked By Intraspinal Microstimulation in Cats

Lemay

Grill

2004

Journal of Neurophysiology

110

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“…A new approach to FES emerged in the form of intraspinal microstimulation (ISMS) to tap into spinal networks involved in the generation of micturition [13]- [15], or patterned movements of the legs [1], [4], [16]- [21]. The lumbosacral region of the spinal cord contains the cell bodies of motoneurons innervating the muscles of the lower extremities.…”

Section: Introductionmentioning

confidence: 99%

Intraspinal microstimulation generates functional movements after spinal-cord injury

Saigal

Renzi

Mushahwar

2004

IEEE Trans. Neural Syst. Rehabil. Eng.

116

113

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Restoring locomotion after spinal-cord injury has been a difficult problem to solve with traditional functional electrical stimulation (FES) systems. Intraspinal microstimulation (ISMS) is a novel approach to FES that takes advantage of spinal-cord locomotor circuits by stimulating in the spinal cord directly. Previous studies in spinal-cord intact cats showed near normal recruitment order, reduced fatigue, and functional, synergistic movements induced by stimulation through a few microwires implanted over a 3-cm region in the lumbosacral cord. The present study sought to test the feasibility of ISMS for restoring locomotion after complete spinal-cord transection. In four adult male cats, the spinal cord was severed at T10, T11, or T12. Two to four weeks later, 30 wires (30 microm, stainless steel) were implanted, under anesthesia, in both sides of the lumbosacral cord. The cats were then decerebrated. Stimulus pulses (40-50 Hz, 200 micros, biphasic) with amplitudes ranging from 1-4x threshold (threshold = 32 +/- 19 microA) were delivered through each unipolar electrode. Kinetics, kinematics, and electromyographic (EMG) measurements were obtained with the cats suspended over a stationary treadmill with embedded force platforms for the hindlimbs. Phasic, interleaved stimulation through electrodes generating flexor or extensor movements produced bilateral weight-bearing stepping of the hindlimbs with ample foot clearance during swing. Minimal changes in kinematics and little fatigue were seen during episodes of 40 consecutive steps. The results indicate that ISMS is a promising technique for restoring locomotion after injury.

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“…It is our belief that only simple FES systems are promising from the clinical point of view. Electrical stimulation of spinal neural circuits, rather than direct activation of motoneurons, will simplify generation of complex motor behaviors (8). Electrical stimulation of the dermatomes, described in this article, is just one possible access to the spinal neural circuitry from the periphery.…”

Section: Discussionmentioning

confidence: 99%