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Static and dynamic components of mechanical impedance of human forearm were evaluated by applying two kinds of perturbations: 1) large viscoelastic loads, and 2) small pseudo-random perturbations. When the task involved the active resistance of the perturbations, both stiffness and viscosity increased relatively to their values in the passive task, the(More)
The firing rate of single cerebellar nuclear neurons was studied during microiontophoretic application of noradrenaline (NA), 5-hydroxytryptamine (5-HT) and their agonists in deeply anesthetized rats. NA application depressed the neuronal firing rate more in the medial nucleus (MN) than in the interpositus (IN) and in the lateral nucleus (LN). These(More)
The effects of noradrenaline (NA) on inhibitory responses to gamma aminobutyric acid (GABA) in neurones of the deep cerebellar nuclei were studied in vivo in rats, using extracellular single-unit recordings and microiontophoretic drug application. NA application altered GABA-evoked responses in 95 % of the neurones tested, but the effects differed between(More)
The effects of dorsal raphe (DR) electrical stimulation on the neuronal activity of vestibular nuclei were studied in anaesthetized rats. The aim was to establish whether the central systems classically involved in nociceptive functions are able to influence vestibular secondary neurons. DR activation induced modifications of the firing in 70% of the tested(More)
The excitatory responses evoked by glutamate and its agonists in secondary vestibular neurons of the rat were studied during microiontophoretic application of 5-hydroxytryptamine (5-HT). Ejection of 5-HT modified neuronal responsiveness to glutamate in 86% of the studied units, the effect being a depression of the excitatory responses in two-thirds of cases(More)
In mesencephalic red nucleus (RN), GABA-induced inhibition of neuronal firing is modulated by noradrenaline acting on alpha2- and beta-adrenoceptors. Since both GABAA and GABAB receptors are present in the rat RN, we have recorded the firing activity of RN neurons in vivo from anaesthetized rats to study how GABAA- and GABAB-mediated effects are modulated(More)
In cats with C4-T2 unilateral dorsal rhizotomy, stimulation of interpositus nucleus of the cerebellum, ipsilateral to the deafferented side, elicits in forelimbs single muscle contractions, which display threshold, latencies and spatial-temporal characteristics similar to those of the muscular responses produced in the other forelimb, upon stimulation of(More)
Microiontophoretic ejection (10-100 nA) of serotonin (5-hydroxytryptamine) into the superior vestibular nucleus induced modifications of the mean firing rate in 87% of the neurons examined. The responses to 5-hydroxytryptamine application were excitatory in 48% of the cells, inhibitory in 29%, and biphasic (inhibitory/excitatory) in the remaining 10%. The(More)
The effects of microiontophoretic application of 5-hydroxytryptamine (5-HT) on the neuronal firing rate of the medial vestibular nucleus (MVN) were studied in anaesthetized rats. Ninety-three % of the units modified their background activity following 5-HT iontophoresis, enhancements of the firing rate being recorded in 42%, decreases in 38% and biphasic(More)
5-hydroxytryptamine (5-HT) was delivered microiontophoretically (20-80 nA) to cells of the lateral vestibular nucleus of anaesthetized rats to test its influence on the spontaneous activity of single neurons. 5-HT increased the rate of firing of 94% of the units tested. The enhancement persisted for up to 700 s after the end of the 5-HT ejection and the(More)