Inhibition of medullary reticulospinal neurons by excitation of the dorsolateral parts of the pons which block movement and muscle tone in rats.

Analysis of the response of 128 reticulospinal neurons in the magnocellular and ventral reticular nuclei showed that 36.7% of these cells responded with short-latency (2-4 msec) action potentials and increased their tonic activity in response to electrical stimulation of the central parts of the hypothalamus, which evoked increases in hindlimb muscle tone in rats. These cells completely stopped producing action potentials during electrical stimulation and during chemical stimulation of the dorsolateral parts of the pons, which inhibited movement and muscle tone.

[Changes in the neuronal activity in the dorsolateral pontine region caused by electrical stimulation of the brainstem regions inhibiting movement and the muscle tone].

Activity of 44 mesencephalic locomotor area's (MLR) units and 38 pontine inhibitory area's (PIA) units was recorded during stimulation of the giganto-cellular reticular nucleus and oral pontine reticular nucleus inducing the hindlimb muscle tone inhibition in decerebrated rats. The muscle tone suppression was always accompanied by a decrease in the MLR and an increase in the PIA unit discharges. Stimulation of the brainstem inhibitory area seems to activate reticulospinal inhibitory system and suppress some MLR units relating to locomotion and muscle tone.

[The inhibition of medullary reticulospinal neurons during the excitation of the dorsolateral portions of the pons blocking movement and muscle tonus in rats].

Hypothalamic stimulation increasing the muscle tone in hindlimbs, and excitation of the pontine dorsolateral areas inhibiting movements and the muscle tone in rats, were studied. Hypothalamic stimulation made 36.7% of the reticulospinal neurones to discharge in the form of short-latency spikes and to increase the muscle tone.

[Neuron reactions of brain structures suppressing motion during development of animal hypnosis in guinea pigs].

Multisensory and motor units are suppressed in hypnosis in the guinea pig giganto-cellular reticular nucleus and in the dorsolateral. pons. In contrast, inhibitory intexneuvons neurons and the ponto-medulla neurons are activated in hypnosis.

[Electrophysiological analysis of interaction between the neuron populations of pons and medulla participating in inhibition of the motor activity].

Neurons of cuneiform, subcuneiform, medial parabrachial, median raphe nuclei were studied. 26-47% units were found to send monosynaptic inputs to the raphe magnus nucleus, gigantocellular reticular and ventral reticular nuclei. 17-43% responded to stimulation of the inhibitory brain stem areas with excitatory-inhibitory reactions.

Neuronal reactions in the dorsolateral pontine area during the immobility response in rats.

Reactions of 277 neurones located in the brain pons dorsolateral portion were analised in staying awake and narcotized rats during immobility reflex, induced by the skin constriction on the neck dorsal surface. Got excited: fast adaptive tactile neurons (n = 32), interneurons (n = 42), and cells forming monosynaptic inputs to the parts of medulla oblongata, which inhibit the movements (n = 10). Were inhibited: somatosensory (n = 42), nociceptive (n = 24) and nonidentificated (n = 14) neurons.

[Neurophysiology and analysis of the phenomenon of catalepsy].

Neurophysiological mechanisms of the photogenic catalepsy (the "animal hypnosis"), genetic catalepsy, and cataplexy are discussed. The data obtained demonstrates a significance of the brainstem structures suppressing motor activity and the muscle tone in these conditions. Motor disorders associated with the general immobility are discussed from the standpoint of the evolutionary theory.

[The effect of the stimulation of sections of the pons that inhibit movement on the neuronal activity of the medial medulla oblongata].

Out of 249 units of the medial medullary area, 40 were ineffective, 25 fired antidromically, 48--orthodromically, 72 were inhibited and 64 developed a tonic firing pattern during stimulation of inhibitory pontine areas. The data obtained revealed that somatosensory neurons were mostly inhibited whereas reticulospinal neurons suppressed the activity of the hindlimb motoneurons.

[Changes in the functional activity of the brain stem system that inhibits movement during the development of cataleptiform states].

Electrical stimulation of the n.cuneiformis and medial parabrachial nucleus inducing the inhibition of locomotor behaviour, was performed in cataleptic and non-cataleptic rats. The stimulation of the inhibitory brainstem zones proved to be more effective in cataleptic animals, the state having been induced by a nociceptive stimulus.

[The interaction of the thalamic parafascicular complex with the brain stem centers that inhibit locomotor activity].

Effects of electrical and chemical stimulation of the thalamus parafascicular complex on the rat behaviour and functional state of the inhibitory brain stem centres were studied in chronic experiments. The electrical stimulation of the parafascicular complex suppressed the locomotion and augmented multiunit activity in the inhibitory brain stem centres. The lesion of the raphe magnus nucleus and the medial portion of the reticular giganto-cellular nucleus eliminated the inhibition.

[The participation of the frontal cortical areas in the regulation of the functions of the inhibitory motor centers in the brain stem].

Effects of electrical and chemical stimulations of the frontal and fronto-parietal cortex on behaviour of rats and functional state of the brain-stem inhibitory centers, was studied in chronic experiments. Functional influences of rostral cortex on the brainstem structures was shown.

[The central neurophysiological mechanisms in the regulation of inhibition].

Electrical and local chemical stimulation of the n. cuneiformis, the parabrachial medial nucleus, the n. raphe median and the n.

[The effect of brain stem structures on the formation of defensive behavior in animals].

Electrical lesions of the nucleus cuneiformis, parabrachial medial nucleus, nucleus raphe median and the nucleus raphe magnus induce an active response of defence. Local microinjections of kainic acid in these sites result in a contrary effect. The findings suggest that inhibitory locomotor system of the brainstem may influence the formation of defensive behaviour in rats.

[The participation of the inhibitory locomotor system of the brain stem in regulating pain sensitivity].

Electrical stimulation of medial parabrachial nucleus, nucleus cuneiformis, Raphe median nucleus and Raphe magnus nucleus induced cataleptic behaviour and analgesic effect in rats. Microinjections of 5,6-dihydroxytriptamine in n. Raphe magnus blocked the antinociception elicited by stimulation of these sites but did not affect the inhibition of locomotion.

[An analysis of the neuronal processes in the activating brain systems of the rat during the acquisition of an instrumental defense reflex].

In chronic experiment, a defensive conditioned reflex was elaborated in rats with electrodes implanted in the reticular oral pons nucleus, cortico-medial group of amygdalar nuclei, ventromedial hypothalamic nucleus and central grey substance of the midbrain. Synchronization of the activity of neuronal groups of emotiogenic formations in the studied brain structures, became enhanced at formation of the conditioned reflex. A dependence was revealed of the level of correlation of limbic neuronal groups activity on functional state of the reticular formation, as well as neurochemical correlation mechanisms.

[Neurochemical mechanisms of regulation in cataleptiform states in animals].

Influence of serotonin- and GABA-ergic systems on cataleptic responses to electrical stimulation of the medial parabrachial nucleus, cuneiform nucleus, median and magnus raphe nuclei, was investigated in chronic experiments on rats. The brainstem structures seem to form a morphofunctional inhibitory system participating in catalepsy.

[Participation of visceral centers of the brain stem in the development of emotional and behavioral responses].

Effect of electrical stimulation of the medial parabrachial nucleus on behaviour, respiration rate, orienting-investigating reaction of rats was studied in chronic experiments.

[Functional changes in the argentaffin cells of the stomach and electrical activity of the brain of the rat after injection of neurotensin into the hypothalamus and 3d ventricle of the brain].

Administration of neurotensin or its analogue into the hypothalamic structures altered the degree of activity synchronization among hypothalamic and brain-stem structures, the synchronization becoming most obvious among ventro-medial nucleus, amygdala and the central grey matter. Administration of the drugs into the 3rd ventricle and paraventricular nuclei suggested antagonistic effects of these peptides at the hypothalamic level. The data obtained could be regarded as local effects of the neuropeptides upon neurons of the paraventricular nucleus and as systemic effects upon argentaffin cells of the stomach antral portion.

[Effect of somatostatin on the neurosecretory cells of the hypothalamic paraventricular nucleus and argentaffin cells of the antral part of the rat stomach].

Administration of somatostatin induced changes of functional activity in all the central and peripheral structures under study. Neuronal activity in the paraventricular nucleus decreased by the 3rd and 15th min after somatostatin injection whereas by the 20th min the firing rate increased. Amount of argenaffin cells was sharply reduced, at that, between the 4th and 15th min which suggested an active release of enterochromaffin cell granules into the blood.