Electrical stimulation of the sural cutaneous afferent nerve controls the amplitude and onset of the swing phase of locomotion in the spinal cat

Abstract

Sensory feedback plays a crucial role in the control of locomotion and in the recovery of function after spinal cord injury. Investigations in reduced preparations have shown that the locomotor cycle can be modified through the activation of afferent feedback at various phases of the gait cycle. We investigated the effect of phase-dependent electrical stimulation of a cutaneous afferent nerve on the locomotor pattern of trained spinal cord-injured cats. Animals were first implanted with chronic nerve cuffs on the sural and sciatic nerves and electromyographic electrodes in different hindlimb muscles. Cats were then transected at T12 and trained daily to locomote on a treadmill. We found that electrical stimulation of the sural nerve can enhance the ongoing flexion phase, producing higher (+129%) and longer (+17.4%) swing phases of gait even at very low threshold of stimulation. Sural nerve stimulation can also terminate an ongoing extension and initiate a flexion phase. A higher prevalence of early switching to the flexion phase was observed at higher stimulation levels and if stimulation was applied in the late stance phase. All flexor muscles were activated by the stimulation. These results suggest that electrical stimulation of the sural nerve may be used to increase the magnitude of the swing phase and control the timing of its onset after spinal cord injury and locomotor training.

Central Pattern Generator for Locomotion: Anatomical, Physiological, and Pathophysiological Considerations

“…Another avenue to increase lower CPG drive and extensor activity may be based on electrical stimulation of ventrolateral tracts near thoracic segmental areas already known for reactivating the lumbar CPG in animal models (Cheng and Magnuson, 2011). Alternatively, direct stimulation of the CPG (e.g., intraspinally, epidurally, or transcutaneously, Holinski et al, 2011; Gorodnichev et al, 2012; Moshonkina et al, 2012) or indirectly by peripheral nerve stimulation (e.g., Guertin et al, 1995; Ollivier-Lanvin et al, 2011) or muscle vibration (Field-Fote et al, 2012) can possibly be used to boost lumbar CPG activation and bipedal stepping expression. Pharmacological aids such as fast-acting and brain-permeable adrenergic α1 agonists (e.g., methoxamine or a regulatory-approved midodrine sold as Amatine) could also possibly help to increase leg extensor activity in UTS patients.…”

Motoneuronal and muscle synergies involved in cat hindlimb control during fictive and real locomotion: a comparison study

“…The methods of animal training, implantations of EMG electrodes, and locomotion data collection have been described elsewhere (Boyce et al 2007;Gregor et al 2006;Ollivier-Lanvin et al 2011;Prilutsky et al 2011) and are described only briefly here. Prior to surgical implantation of EMG electrodes, cats were trained to walk on a treadmill or across a walkway (3.0 ϫ 0.4 m) with Plexiglas walls with the use of operant conditioning methods and food reward.…”

“…Locations of the EMG electrodes were verified by mild electrical stimulations through the implanted wires. Ip 1 4 175 Ip 5 33 512 SmAB 41 91 2,641 AB 5 30 482 Sart(A or M) 34 77 2,059 SartM 6 44 792 PBSt 29 69 1,914 PB 5 28 432 RF 9 27 652 RF 5 21 363 VA 8 15 293 VA 6 40 742 TA 43 92 2,662 TA 6 36 665 Plong 12 27 876 EDL 22 After recovery (10 -14 days), EMG activity (sampling rate 2,400 Hz, treadmill; 3,000 Hz, overground) and kinematics of walking, as well as ground reaction forces during overground walking, were recorded synchronously as previously described (Boyce et al 2007;Gregor et al 2006;Ollivier-Lanvin et al 2011;Prilutsky et al 2011; see Table 1). Cats walked overground at a self-selected speed (typically between 0.4 and 0.6 m/s) and on the motorized treadmill at a speed of 0.4 m/s.…”

The effect of timing electrical stimulation to robotic-assisted stepping on neuromuscular activity and associated kinematics

“…The ability to modulate spinal plasticity, and resulting functional recovery, by hind-limb afferent stimuli has also been demonstrated in a number of previous studies [41][42][43]. Recent evidence that FES of cutaneous afferent pathways is effective in modulating the generation of stepping in cats and humans with SCI [44][45] could indicate that applied stimulation may enhance afferent modulation of spinal circuitry.…”