Adrenergic receptors modulate motoneuron excitability, sensory synaptic 1 transmission and muscle spasms after chronic spinal cord injury. 2 Rank MM, Murray KC, Stephens MJ, D’Amico J, Gorassini MA, and Bennett DJ 3 Centre for Neuroscience, University of Alberta, Edmonton, Alberta, Canada 4 5 6 Running Title: Adrenergic receptors modulate spasms. 7

Fast glutamatergic transmission via ionotropic receptors is critical for the generation of locomotion by spinal motor networks. In addition, glutamate can act via metabotropic glutamate receptors (mGluRs) to modulate the timing of ongoing locomotor activity. In the present study, we investigated whether mGluRs also modulate the intensity of motor output generated by spinal motor networks. Appli...

BACKGROUND Depression of spinal cord motoneuron excitability has been proposed to contribute to surgical immobility. The H-reflex, which measures alpha-motoneuron excitability, is depressed by volatile anesthetics, whereas the action of propofol is unknown. The objective of this study was to determine the effects of propofol anesthesia on the H-reflex. METHODS In 13 patients (group 1), H-refl...

The excitability of thenar motoneurons (reflected by F-wave persistence and amplitude) and thenar muscle force were measured during a stimulation protocol (90 s of 18-Hz supramaximal electrical stimulation of the median nerve) designed to induce muscle fatigue (force decline). Data from muscles (n = 15) paralyzed by chronic cervical spinal cord injury were compared with those obtained from cont...

Stroke survivors often exhibit abnormal motoneuron excitability, manifested clinically as spasticity with exaggerated stretch reflexes in resting muscles. We examined whether this abnormal excitability is a result of increased activation of intrinsic voltage-dependent persistent inward currents (PICs) or whether it is a result of enhanced synaptic inputs to the motoneuron. This distinction was ...

The excitability of lumbar motoneurons in the cat is increased during fictive locomotion induced by stimulation of the mesencephalic locomotor region (MLR). This change in excitability has previously been demonstrated experimentally. During fictive locomotion: (1) the afterhyperpolarization (AHP) is reduced and (2) the voltage threshold for production of an action potential is lowered. The exci...

We investigated the effects of water swallowing, pharyngeal stimulation, and oropharyngeal anesthesia on corticobulbar and craniobulbar projections to human swallowing musculature. Changes in pathway excitability were measured via electromyography from swallowed intraluminal pharyngeal and esophageal electrodes to motor cerebral and trigeminal nerve magnetic stimulation. After both water swallo...

Spasticity is commonly observed after chronic spinal cord injury (SCI) and many other central nervous system disorders (e.g., multiple sclerosis, stroke). SCI-induced spasticity has been associated with motoneuron hyperexcitability partly due to enhanced activation of intrinsic persistent inward currents (PICs). Disrupted spinal inhibitory mechanisms also have been implicated. Altered inhibitio...

30 Stroke survivors often exhibit abnormal motoneuron excitability, manifested clinically 31 as spasticity with exaggerated stretch reflexes in resting muscles. We examined whether this 32 abnormal excitability is a result of increased activation of intrinsic voltage-dependent 33 persistent inward currents (PICs), or whether it is due to enhanced synaptic inputs to the 34 motoneuron. This disti...