Phase-dependent modulation of monosynaptic reflexes has been reported for several muscles of the lower limb of uninjured rats and humans. To assess whether this step-phase-dependent modulation can be mediated at the level of the human spinal cord, we compared the modulation of responses evoked simultaneously in multiple motor pools in clinically complete spinal cord injury (SCI) compared with n...

During the evolution of bipedal modes of locomotion, a sequential rostrocaudal activation of trunk muscles due to the undulatory body movements was replaced by more complex and discrete bursts of activity. Nevertheless, the capacity for segmental rhythmogenesis and the rostrocaudal propagation of spinal cord activity has been conserved. In humans, motoneurons of different muscles are arranged i...

Recent studies indicate a modular organization of the nociceptive withdrawal reflex system. Each module has a characteristic receptive field, closely matching the withdrawal movement caused by its effector muscle. In the rat, the strength of the sensory input to each module is tuned during the first postnatal weeks, i.e., erroneous spinal connections are depressed, and adequate connections are ...

Anuran metamorphosis includes a complete remodeling of the animal's biomechanical apparatus, requiring a corresponding functional reorganization of underlying central neural circuitry. This involves changes that must occur in the coordination between the motor outputs of different spinal segments to harmonize locomotor and postural functions as the limbs grow and the tail regresses. In premetam...

Spinal reflexes have traditionally been treated as separate from voluntary movements. However, animal experiments since the 1950s and human experiments since the 1970s have documented that sensory activities in afferents from muscles, skin, and joints are integrated with descending motor commands at the level of common spinal interneurons. Two different roles of this sensorimotor integration at...

Spinal manipulative therapy (SMT) is common in the management of low back pain (LBP) and has been associated with changes in muscle activity, but evidence is conflicting. This study investigated the effect of SMT on trunk muscle activity in postural tasks in people with and without LBP. In 20 subjects (10 with LBP and 10 controls), EMG recordings were made with fine-wire electrodes inserted int...

OBJECTIVE To use a combination of electrophysiological techniques to determine the extent of preserved muscle activity below the clinically-defined level of motor-complete spinal cord injury. METHODS Transcranial magnetic stimulation and vestibular-evoked myogenic potentials were used to investigate whether there was any preserved muscle activity in trunk, hip and leg muscles of 16 individual...

A model of the spinal cord neural circuitry for control of cat hindlimb movements during locomotion was developed. The neural circuitry in the spinal cord was modeled as a network of interacting neuronal modules (NMs). All neurons were modeled in Hodgkin-Huxley style. Each NM included an αmotoneuron, Renshaw, Ia and Ib interneurons, and two interneurons associated with the central pattern gener...

Spinal myoclonus is a rare disorder characterized by myoclonic movements in muscles that originate from several segments of the spinal cord and usually associated with laminectomy, spinal cord injury, post-operative, lumbosacral radiculopathy, spinal extradural block, myelopathy due to demyelination, cervical spondylosis and many other diseases. On rare occasions, it can originate from the peri...

Clinical evaluation of clonus in spastic muscles was performed by comparing reflex path length with clonus frequency for different muscles in the same patient. It was found that clonus frequency varied inversely with reflex path length (r = 0.84, p less than 0.001). The findings confirm that clonus is generated by a peripheral mechanism of self re-excitation rather than a central spinal pacemaker.