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At least 19 recordsLinked to original sources
PubMed1979

Effects of diphenylhydantoin on the spontaneous activity of Purkinje, nucleus interpositus, red nucleus and motor cortex cells.

(1) Extracellular multiunit recordings were made of the spontaneous activity in cerebellar Purkinje cells, nucleus interpositus, red nucleus and sensorimotor cortex in acute cat preparations. (2) Changes in this spontaneous neural activity produced by the administration of diphyenylhydantoin (DPH) were studied. DPH was infused i.v., generally at a concentration of 2.5 mg/ml and at a rate varying from 0.08 to 0.48 mg/kg/min. Two different patterns of infusion were used: fixed time, variable rate and variable time, fixed rate. Pulsed doses were also given at intervals of 5--10 min. (3) DPH at a level of 10--20 mg/kg produces a significative initial deceleration in all structures followed by a significative acceleration in the Purkinje cells, nucleus interpositus and red nucleus as a dose of 20--30 mg/kg is reached. Higher levels caused a profound depression of multiunit activity. (4) The activation produced by DPH is oscillatory (3--5/min) in character and is composed of 'trains' which occur at a rate of 20--30/sec with very rapid discharge frequencies (600--800 Hz). (5) A direct significant correlation was found between DPH serum levels and the intravenously administered dose. The activating DPH dose (20--30 mg/kg) corresponded to serum levels of 24--32 micrograms/ml. (6) The possibility is discussed whether the anticonvulsant action of DPH may be due in part to the production of rhythmic oscillatory activity in the cerebello-rubro-olivo-cerebellar ciruit and the depression of the cerebellothalamic-cortical pathway.

Animals↗
PubMed1979

Interaction of peripheral and cerebellar inputs to red nucleus neurons.

In chloralose anesthetized cats responses of red nucleus neurons to cerebellar cortical or peripheral stimulation are described. Interactions between cerebellar (conditioning) and peripheral (test) stimulations were studied at various interstimulus intervals. Peripheral stimulation alone typically evoked a complex response consisting of an early (15 ms latency) burst, a period of depression of activity (inhibition, lasting up to 300 ms) and a late, long-lasting (on an average 300 ms) excitation. Cerebellar cortical stimulation resulted in a similar pattern of response; but it was composed predominantly of only two phases, an initial inhibition followed by a prolonged late discharge. With conditioning- testing intervals in a range of 10-150 ms, depending on the cell, there was a conspicuous depression of the sh0i.t-latency test excitation, followed by a prominent potentiation of this component. An occlusion of the inhibitory or late excitatory responses occurred when conditioning-testing stimuli were applied with an interval shorter than 0.5 s. It is suggested that the early excitation and the subsequent late components are generated in the red nucleus by independent mechanisms. The initial depression of the early test response is explained as an effect of Purkinje cell inhibition, and the later potentiation as a result of temporary blockage of the cerebellar cortex to afferent input.

Animals↗
PubMed1978

A quantitative electron microscope study of cerebellar axon terminals on the magnocellular red nucleus neurons in the cat.

In the red nucleus (RN) of the cat, the bouton covering ratio (BCR: the ratio of whole somatic surface length and that covered with axon terminals) and the density of axon terminals in contact with somatic profiles (DAST: the number of axosomatic terminals per micron of somatic surface membrane) were calculated in each neuronal somatic profile over 60 micron in diameter. The mean BCR was 61.4 +/- 1.43 (S.E. M.)%. The mean DAST of axosomatic terminals filled with spherical synaptic vesicles (S-terminals) was 27.7 +/- 0.95, and that of terminals with pleomorphic and/or flattened vesicles (F-terminals) was 10.3 +/- 1.12. Subsequently, sequential changes of the BCR and DAST of intact terminals were examined in the RN deafferented from the cerebellorubral fibers. The mean BCR and DAST were decreased most markedly during the survival period of 4-7 days; thus decrease was chiefly due to degeneration of S-terminals (BCR: 16.7 +/- 1.17 %, DAST of S-terminals: 7.1 +/- 1.12, DAST of F-terminals: 5.8 +/- 1.22). In the RN 11-63 days after the operation, both the BCR and DAST tended to re-increase slightly and the majority of the re-increased terminals appeared to be F-terminals. Possible meanings of this re-increase of axosomatic terminals are discussed.

Afferent Pathways↗
PubMed1976

Brachium conjunctivum-red nucleus synaptic system in the baboon.

Electrophysiological properties of the brachium conjunctivum-red nucleus (BC-RN) synaptic system were studied in barbiturate-anesthetized baboon (Papio). Topographic recordings from the mesencephalon demonstrated that most of the BC-evoked activity was restricted to an area histologically identified as red nucleus; however, some brachium-evoked activity was recorded from the surrounding mesencephalic reticular formation. Short latency BC-evoked activity was also recorded from the pons in the region of nucleus reticularis tegmenti pontis. The majority of the BC fibers were found to conduct at a rate of 44 m/sec; a second group of BC fibers with a slower conduction velocity of 23 m/sec was also observed. Brachium-evoked responses recorded from magnocellular and pravicellular RN neurons were short latency responses consistent with monosynaptic activation of these RN neurons by the BC fibers. The BC-RN synaptic system was found to be a very secure synaptic system and could transmit activity at high rates of stimulation with little or no failure. The responsiveness of the BC fibers was found to be similar to that of optic nerve fibers and pyramidal tract fibers, both of which have been characterized as being similar to peripheral A fibers. The responsiveness of the BC-RN synaptic system began to decrease 5 msec after a single or repetitive transmission and was reduced to about 50% of normal responsiveness at 34 msec. This period of reduced postsynaptic responsiveness was associated with a reduction in presynaptic input to RN and suggest that a disfacilitation at the level of the deep cerebellar nuclei may be in part responsible for the subnormal responsiveness of the BC-RN synaptic system.

Animals↗
PubMed1978

Discharge of red nucleus neurons during voluntary muscle contraction: activity patterns and correlations with isometric force.

Discharges of red nucleus neurons were analyzed in the cat during voluntary muscle contractions performed under isometric and anisometric conditions. The observations established: (1) that neurons of the red nucleus modulate their firing in advance of the motor output under both conditions; (2) that increased activity of these neurons is specific to the direction of the force exerted ; (3) that this increase is primarily related to the magnitude of the rate of force change generated by the animal.

Action Potentials↗
PubMed1978

Organization of the mammalian red nucleus and its interconnections with the cerebellum.

The red nucleus in monkeys and rats consists of a magnocellular, rubrospinal portion which receives its cerebellar information from the nucleus interpositus, and a parvocellular, rubroolivary portion which receives cerebellar afferents from the nucleus lateralis. Distinct interpositorubrospinal and dentatorubroolivary projections are therefore common to these 2 species.

Animals↗
PubMed1979

Cells of origin of the frontal projections to magnocellular and parvocellular red nucleus and superior colliculus in cynomolgus monkey. An HRP study.

Cells of origin of frontal cortical projections to parvocellular and magnocellular red nucleus (MRN) and superior colliculus were identified by means of retrograde HRP transport. The cells projecting to parvocellular red nucleus (PRN) are mainly located in areas 6 and 4, and are situated in the upper part of layer V, i.e. above the Betz cells, while those projecting to MRN are mainly located posteriorly in area 4, and are situated deep in layer V, i.e. at the level of the Betz cells. The neurons projecting to superior colliculus are located deep in layer V of areas 9, 8 and 6.

Animals↗
PubMed1978

Dependence of the activity of interpositus and red nucleus neurons on sensory input data generated by movement.

Cats performed flexion movements of the forearm, and the discharge of interpositus and red nucleus neurons was examined for relationships to the motion and to the EMG activity of agonist and antagonist muscles. It is shown that, over a wide range in the time course of the motion, the activity of the neurons is covariant with both the EMG and the movement parameters, in particular, the velocity. Also, the discharge of the interpositus neurons is modulated in phase with the velocity of passive movement. It is concluded that during fast, intentional movements, sensory input data generated by motion is a major determinant of the output of the interpositus nucleus. Furthermore, the results are consistent with the concept that this output provides a continuous modulation of spinal segmental mechanisms by way of the red nucleus and rubrospinal tract.

Animals↗
PubMed1977

[Excitability of the senso-motor cortex and red nucleus of rabbits with different levels of cortical potential spatial synchronization].

The motor reaction of the rabbit to the threshold electrical stimulation of the sensomotor cortex and red nucleus was studied to determine excitability of these structures. Under conditions of the computer-controlled experiment the excitability of the two structures was compardd for situations characterized by different levels of cortical potential correlation. An increase in the spatial synchronization of the cortical potentials is shown to be accompanied by intensification in excitability of the sensomotor cortex and red nucleus. This intensification seems to be one of possible neurophysiological mechanisms of the probability increase for the effector reaction to sensory stimuli when the cortical spatial synchronization rises.

Animals↗
PubMed1979

Projections of precentral and premotor cortex to the red nucleus and other midbrain areas in Macaca fascicularis.

Midbrain projections from the precentral and premotor cortex were studied autoradiographyically in seven macaques. Earlier findings of Kuypers and Lawrence (1967) based on silver impregnated axonal degeneration were largely confirmed and partly extended. Laminar projections into the parvocellular red nucleus were found bilaterally from the somatotopic representation areas of the precentral cortex and three main divisions of premotor cortex (ventral, dorsal, and medial). The heaviest contralateral projection was recorded from the medial hemispheric aspects of area 6 (partly identical with the supplementary motor cortex). Homolateral projections were found from the limb areas of the precentral motor cortex to the magnocellular portion of the red nucleus and direct evidence for the overlap between corticorubral projections and corresponding areas of origin of the rubrospinal tract was obtained. Other projections concerned N. Darkschewitsch, N. Edinger-Westphal, suprarubral and dorsal mesencephalic reticular formation and adjacent lateral periaqueductal grey, substantia nigra, pretectal region, superior colliculus and N. tegmenti pedunculo-pontinus.

Animals↗
PubMed1978

Electron-microscopic study of the maturing rat red nucleus. I. The large-neuron population.

The maturing large neurons of the rat red nucleus in animals ranging in age from 1 to 21 days of postnatal life were studied ultrastructurally. Days 1--6 were characterized by rapid morphologic maturation occurring concomitantly with the onset of synaptogenesis. Morphogenesis was confined to the soma, while the first synaptic contacts were also formed in relationship to the soma. Days 6--9 demonstrated continued somal morphogenesis exemplified by cytoplasmic expansion and by the conspicuous presence of perisomatic and growth cone processes. Proximal dendritic morphogenesis was initiated, and synaptogenesis became complex with synaptic sites occurring in relation to the neuronal soma, the perisomatic processes and proximal dendrites. Days 9--15 were characterized by the completion of somal and proximal dendritic morphogenesis and by a massive degree of synaptogenic activity. During this interval, the soma lost perisomatic and growth cone processes, while somatic spines appeared. By the end of this period the neuronal soma and the proximal dendrites appeared mature in terms of both morphology and synaptic input. Complete neuronal maturation was ultimately attained by day 21 of postnatal life.

Animals↗
PubMed1975

A cytoarchitectonic and Golgi study of the red nucleus in the rat.

The cytology of rubral neurons was investigated using both paraffin and 1 mu thick Epon sections. The neurons were divided into four size categories which form a continuum with regard to cellular characteristics. Giant neurons (greater than 40 mu) and large neurons (26-40 mu) predominate in the caudal one-third of the nucleus. Large neurons extend up the ventral, medial and lateral borders of the nucleus into its middle one-third. The caudal one-third of the nucleus together with this extension of large cells is designated as the magnocellular part of the nucleus. The more rostral part of the nucleus contains predominantly small (less than 20 mu) and medium size (20-25 mu) neurons, and this constitutes the parvocellular part of the nucleus. The characteristics of each cell type are described. Camera lucida drawings of the rubral neurons were made in three different planes of section, and the extent of the magnocellular and parvocellular portions of the nucleus was determined. Dorsomedial and ventrolateral subgroups of the magnocellular part of the nucleus are found 300-400 mu from the caudal pole. A lateral horn of small and medium size neurons with the addition of a few large neurons extends from the lateral part of the nucleus 500-700 mu from the caudal pole. Golgi preparations of the red nucleus were examined in three planes of section. Giant and large neurons display short spines on the soma and also, along the entire length of the dendrites. Inaddition, more elongate spinous processes are seen on these dendrites and are frequently aggregated into tufts at loci on the dendrites or at their terminations. The dendrites of these neurons radiate in all directions from the soma but remain within the confines of the nucleus. Medium size neurons demonstrate radially arranged dendrites. Sparsely positioned spines are seen along the length of the dendrites but are absent on the soma. A number of such neurons demonstrate tufts of elongate spines on their dendrites. The dendrites of small neurons branch infrequently and remain within the confines of the nucleus. A few dendritic but no somatic spines are seen in association with these neurons.

Animals↗
PubMed1978

Red nucleus cell activity in awake cats during a placing reaction.

It is known that the discharges of the posterior red nucleus (RN) cells are modulated during locomation (Orlovsky, 1972). The aims of the present investigation were to look for a possible relationship between the unitary activity of RN cells and movements as well as postural reactions of the forelimbs. In the experimental arrangement used, the cat stood on four transducers which recorded to forces on each limb. The animal was restrained by a hammock supporting a part of the total body weight. A horizontally moving plate touched one forepaw and pushed it backwards until a placing mavement was induced. During the first part of the sequence, the mechanically stimulated limb was actively unloaded just prior to the placing movement, while the contralateral forelimb simultaneously presented a loading postural reaction. The results can be summarized and interpreted in the following way: 1. The RN cells exhibit large variations of discharge frequencies during phasic muscular activities linked to movement and to postural adjustments, but no correlations can be established between tonic cell activity and static postural forces exerted by the limb. 2. During the swing phase, the neuronal activity of some RN cells is maximal during flexion, while for others the maximum is during extension. 3. When there is a modification in frequency at the onset of the placing reaction relative to activity during the unloading reaction, the beginning of this change occurs after the onset of the movement as recorded by a potentiometer placed at the elbow joint. 4. The increases of frequency are higher during reciprocal muscle activation (during the movement) than during coactivation of antagonistic muscles (during the postural loading reaction). 5. During the loading reaction (with mostly extensor activation) the frequency of firing of those neurones discharging during the flexion phase. Thus the data may indicate that the RN is included in a feed-back loop which is linked not to muscle activities but rather to phasic spinal reflexes.

Action Potentials↗
PubMed1977

Pharmacology of the brachium conjunctivum: red nucleus synaptic system in the baboon.

Acetylcholine, biogenic amines, and certain amino acids were applied by microiontophoresis to parvicellular and magnocellular red nucleus (RN) neurons of baboon while recording brachium conjunctivum (BC)-evoked and amino acid-evoked unit discharge from these neurons. Glycine, gamma-aminobutyric acid, and beta-alanine were potent depressants of BC-RN synaptic transmission, amino acid-evoked firing, and spontaneous activity of all RN neurons studied. Glycine was clearly more potent than the other 2 depressant amino acids. L-Glutamic and DL-homocysteic acid were strong excitants of all RN neurons tested. Dopamine, noradrenaline, and 5-hydroxytryptamine depressed the excitability of both parvicellular and magnocellular RN neurons; no excitatory effects were observed with these biogenic amines on RN neurons. Acetylcholine increased the rate of firing of spontaneously discharging parvicellular RN neurons and facilitated the amino acid-induced firing of these same neurons. Acetylcholine did not facilitate BC-RN synaptic transmission nor could this transmission be blocked by cholinergic antagonists. Unlike parvicellular RN neurons, the responsiveness of magnocellular neurons was either unaltered by acetylcholine or slightly decreased. These experiments demonstrate a difference in the pharmacologic responsiveness of parvicellular and magnocellular RN neurons to acetylcholine but do not provide evidence for a cholinergic input to RN via the brachium conjunctivum.

Acetylcholine↗
PubMed1976

Comparison between red nucleus and precentral neurons during learned movements in the monkey.

Monkeys were trained to depress a hold key for a period of 2 sec. After this hold period, either a red or a green cue lamp appeared in random sequence. The red lamp required the monkey to move his hand from the hold key to a target button within 1 sec of the cue presentation. The green lamp required continued depression of the hold key for 1 sec following presentation of the cue. Correct performance was reinforced with fruit juice. In comparing poststimulus and peri-response latencies of 48 red nucleus (RN) and 46 percentral gyrus (PG) units related to the arm movement triggered by the red lamp, the onset of activity in most RN units occurred after the onset of activity in most PG neurons. For 48 RN neurons, the peak of the distribution of onset times was shifted 120 msec later than for 46 neurons. This delay between PG and RN is even greater than the delay between PG and postcentral gyrus. It is known that RN receives powerful inputs both from the sensorimotor cortex and from cerebellum--and it seems possible that the activity in RN was dependent on the combined action of these two inputs, with sensory feedback from movement (relayed via postcentral gyrus and/or cerebellum) being one input, and a central program from cerebellum and/or precentral gyrus being the other input.

Action Potentials↗
PubMed1979

Instrumental conditioned responses in cats with bulbar pyramid and red nucleus lesions.

Adult cats were trained to insert a forelimb into horizontally mounted transparent cylinders and then either depress a barrier or pull a sliding tray against resistance in order to receive food reward. Unilateral lesions of both bulbar pyramid and red nucleus resulted in severe neurological deficits. However, the instrumental tasks were soon accomplished at preoperative levels of rapidity and strength, although movements of the digits and wrist were reduced and adjustive movements occurred chiefly at more proximal joints. These results support our hypothesis that conditioned and unconditioned behaviors are mediated through different mechanisms.

Animals↗