The effects of chlorphenesin carbamate (CPC) and mephenesin on spinal neurons were investigated in spinal rats. CPC (50 mg/kg i.v.) inhibited the mono-(MSR) and poly-synaptic reflex (PSR), the latter being more susceptible than the former to CPC depression. Mephenesin also inhibited MSR and PSR, though the effects were short in duration. CPC had no effect on the dorsal root potential evoked by ...

Skeletal muscle tone is modulated in a stereotypical pattern across the sleep-wake cycle. Abnormalities in this modulation contribute to most of the major sleep disorders; therefore, characterizing the neurochemical substrate responsible for transmitting a sleep-wake drive to somatic motoneurons needs to be determined. Glutamate is an excitatory neurotransmitter that modulates motoneuron excita...

Cerebral palsy (CP) is a permanent disorder caused by a lesion to the developing brain that significantly impairs motor function. The neurophysiological mechanisms underlying motor impairment are not well understood. Specifically, few have addressed whether motoneuron or peripheral axon properties are altered in CP, even though disruption of descending inputs to the spinal cord may cause them t...

Previous studies have demonstrated that plantar cutaneous afferents can adjust motoneuron excitability, which may contribute significantly to the control of human posture and locomotion. However, the role of plantar cutaneous afferents in modulating the excitability of stretch and H-reflex with respect to the location of their excitation remains unclear. In the present study, it was hypothesize...

background and objective: sciatic nerve transection is characterized by a rapid wave of motoneuron death associated with progressive synaptic lesions. the purpose of this study was to evaluate the long term synaptic changes. materials and methods: this basic study was carried out on paraffin- or resin-embedded tissue blocks for evaluation of synaptophysin and choline acetyl transaferase (chat) ...

In the months after spinal cord injury, motoneurons develop large voltage-dependent persistent inward currents (PICs) that cause sustained reflexes and associated muscle spasms. These muscle spasms are triggered by any excitatory postsynaptic potential (EPSP) that is long enough to activate the PICs, which take > 100 ms to activate. The PICs are composed of a persistent sodium current (Na PIC) ...

INTRODUCTION Under natural motor control, repetitive firing of motoneurons is transmitted by their motor axons to muscle fibers in the “one to one” fashion that allows the analysis of human motoneuron firing via recordings of motor unit (MU) action potentials (see Kernell, 2006; Heckman and Enoka, 2012). However, when axons are diseased or damaged, local increasing axonal excitability may resul...

Since its first description in 1874 by Charcot, the hallmark feature of ALS is the progressive degeneration of upper and lower motoneurons (Charcot, 1874). In the spinal cord, motoneuron degeneration starts long before symptom onset and advances in a size-related fashion, in which large-size alpha-motoneurons degenerate first followed by small-size alpha-motoneurons (Pun et al., 2006; Hegedus e...

33 Hindlimb motoneuron excitability was compared among exercise-trained (E), sedentary 34 (S), and spinal cord transected (T) Sprague-Dawley rats by examining the slope of the 35 frequency-current (F/I) relationship, using standard intracellular recording techniques in rats 36 anesthetized with ketamine/xylazine. The T group included spinal transected and spinal isolated 37 rats; the E animals ...