introduction: the thyroid hormones have profound effects on the development of neuromuscular system. these hormones exert their influence on both muscle fibers and related motoneurons during development. the masseter is one of the most important muscles for mastication in mammals. we attempted to evaluate the effect of thyroid hormone deficiency on the morphological characteristics of masseteri...

A hallmark of rapid eye movement (REM) sleep is a potent suppression of postural muscle tone. Motor control in REM sleep is unique because it is characterized by flurries of intermittent muscle twitches that punctuate muscle atonia. Because somatic motoneurons are bombarded by strychnine-sensitive IPSPs during REM sleep, it is assumed that glycinergic inhibition underlies REM atonia. However, i...

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...

Interactions between ingrowing nerve fibers and their target tissues form the basis for functional connectivity with the central nervous system. Studies of the developing dental pulp innervation by nerve fibers from the trigeminal ganglion is an excellent example of nerve-target tissue interactions and will allow specific questions regarding development of the dental pulp nerve system to be add...

We demonstrate the presence of nitric oxide synthase containing fibers within the guinea pig trigeminal motor nucleus and describe the effects of nitric oxide (NO) on trigeminal motoneurons. Using immunohistochemical techniques, we observed nitrergic fibers displaying varicosities and giving rise to bouton-like structures in apposition to retrogradely labeled motoneuron processes, most of which...

The supratrigeminal region (SupV) receives abundant orofacial sensory inputs and descending inputs from the cortical masticatory area and contains premotor neurons that target the trigeminal motor nucleus (MoV). Thus it is possible that the SupV is involved in controlling jaw muscle activity via sensory inputs during mastication. We used voltage-sensitive dye, laser photostimulation, patch-clam...

Evoked potential was recorded by needle electrode from the oculomotor nucleus in decerebrate cats, following electrical stimulation of the inferior oblique nerve. The evoked potential was usually triphasic, but complex potential with the second and third negative leaves, or with long latency negative waves, was incidentally recorded depending upon the position of the recording electrode. In the...

To initiate and maintain bursts (and plateau potentials) in the presence of serotonin, guinea pig trigeminal motoneurons utilize L-type Ca2+ and persistent Na+ inward currents. However, the intrinsic currents that contribute to burst termination and determine the duration of the interburst interval are unknown. Therefore we investigated the roles of outward currents, whose slow activation is co...