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At least 145 records · Page 8Linked to original sources
PubMed2002

Cerebellar input to magnocellular neurons in the red nucleus of the mouse: synaptic analysis in horizontal brain slices incorporating cerebello-rubral pathways.

We studied the synaptic input from the nucleus interpositus of the cerebellum to the magnocellular division of the red nucleus (RNm) in the mouse using combined electrophysiological and neuroanatomical methods. Whole-cell patch-clamp recordings were made from brain slices (125-150 microm) cut in a horizontal plane oriented to pass through both red nucleus and nucleus interpositus. Large cells that were visually selected and patched were injected with Lucifer Yellow and identified as RNm neurons. Using anterograde tracing from nucleus interpositus in vitro, we examined the course of interposito-rubral axons which are dispersed in the superior cerebellar peduncle. In vitro monosynaptic responses in RNm were elicited by an electrode array placed contralaterally in this pathway but near the midline. Mixed excitatory post-synaptic potentials (EPSPs)/inhibitory post-synaptic potentials (IPSPs) were observed in 48 RNm neurons. Excitatory components of the evoked potentials were studied after blocking inhibitory components with picrotoxin (100 microM) and strychnine (5 microM). All RNm neurons examined continued to show monosynaptic EPSPs after non-N-methyl-D-aspartate (NMDA) glutamate receptor components were blocked with 10 microM 6,7-dinitroquinoxaline-2,3-dione or 5 microM 2,3-dihydro-6-nitro-7-sulfamoyl-benzo(f)-quinoxaline (NBQX; n=12). The residual potentials were identified as NMDA receptor components since they (i) were blocked by the addition of the NMDA receptor antagonist, D,L-2-amino-5-phosphonovaleric acid (APV), (ii) were voltage-dependent, and (iii) were enhanced by Mg(2+) removal. Inhibitory components of the evoked potentials were studied after blocking excitatory components with NBQX and APV. Under these conditions, all RNm neurons studied continued to show IPSPs. Blockade of GABA(A) receptors reduced but did not eliminate the IPSPs. These were eliminated when GABA(A) receptor blockade was combined with strychnine to eliminate glycine components of the IPSPs. Thus, IPSPs evoked by midline stimulation of the superior cerebellar peduncle, while blocking alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) and NMDA receptors, raise the possibility of direct inhibitory inputs to RNm from the cerebellum. In summary we propose that the special properties of the NMDA receptor components are considered important for the generation of RNm motor commands: their slow time course will contribute a steady driving force for sustained discharge and their voltage dependency will facilitate abrupt transitions from a resting state of quiescence to an active state of intense motor command generation.

Animals↗
PubMed1982

Velocity signals related to hand movements recorded from red nucleus neurons in monkeys.

Neural activity of the red nucleus was studied in monkeys trained to operate devices requiring shoulder, elbow, wrist, hand, or finger movements. Single cell activity was more closely related to movements of the hand and fingers than to movements of the other joints. Discharge consistently preceded movements by a constant time interval; duration of discharge was highly correlated with the duration of movement; and discharge rate was highly correlated with movement velocity. These data suggest a role for the rubrospinal pathway in the initiation and control of hand movements.

Action Potentials↗
PubMed1997

The cerebellum and red nucleus are not required for In vitro classical conditioning of the turtle abducens nerve response.

The role of the cerebellum during motor learning is a controversial issue. Many authors have suggested that the cerebellum and its connections with the red nucleus are essential for the acquisition of the conditioned eye blink reflex. Although there is little argument that the cerebellum is an important component to the generation of the conditioned response (CR), a number of studies have suggested that the cerebellum is not essential for conditioning. Using an in vitro model of the classically conditioned turtle abducens nerve response, we investigated the effect of cerebellar and red nucleus lesions on the acquisition, extinction, and reacquisition of CRs. Neural discharge was recorded from the abducens nerve after a single shock unconditioned stimulus (US) was applied to the ipsilateral trigeminal nerve. When the US was paired with a conditioned stimulus (CS) applied to the posterior eighth, or auditory, nerve, a positive slope of CR acquisition was recorded in the abducens nerve. After extinction stimuli in which the CS and US were alternated, the number of CRs decreased to near zero. When the CS and US were once again paired, reacquisition at a faster rate was recorded. The CRs showed unusual timing features compared with preparations in which the cerebellum was intact; they had significantly shorter latencies and showed burst-like responses. These data demonstrate that it is possible to classically condition this in vitro preparation in the absence of the cerebellum and red nucleus. However, the latencies of CRs were found to be dramatically altered in the cerebellar-lesioned preparations, suggesting that the cerebellum does play a role in the timing of the CR.

Abducens Nerve↗
PubMed2003

Facilitation of the jaw reflexes by stimulation of the red nucleus in the rat.

The effects of the red nucleus (RN) stimulation on the jaw-opening reflex (JOR) and the masseteric monosynaptic reflex (MMR) were studied in anesthetized rats. The JOR was evoked by electrical stimulation of the inferior alveolar nerve. The MMR was evoked by electrical stimulation of the mesencephalic trigeminal nucleus. The JOR and the MMR were recorded as electromyographic responses of the anterior belly of the digastric and the masseter muscles, respectively. The conditioning electrical stimulation of the RN facilitated both the JOR and the MMR bilaterally. The facilitatory effect on the JOR was much larger than that on the MMR. Additionally, microinjection of monosodium glutamate into the RN also elicited facilitation of the JOR and the MMR. The results suggest the RN plays an important role in reflex control of jaw movements.

Animals↗
PubMed1987

Parametric relationships of individual digit movements to neuronal discharges in primate magnocellular red nucleus.

Single units were recorded in the magnocellular red nucleus (RNm) while digit movements were monitored in a monkey performing on an individual digit device. The monkey was trained to press switches for water reward while optical systems of infrared emitters and diodes were taped to thumb, index, middle and ring digits for monitoring movements. Of 53 neurons recorded while operating the individual digit device, 9 showed statistically significant parametric relationships with movement velocity and duration. Onset of activity preceded movement by an average of 90 +/- 26 ms. This result suggests that a small group of neurons in the forelimb area of RNm in the monkey is parametrically related to individual digit movements, even though the majority of neurons are related to grouped movements of the hand and digits as previously reported.

Animals↗
PubMed1995

Behavioral and biochemical changes after bilateral electrolytic lesions of the red nucleus of rat.

Bilateral electrolytic lesions of the red nucleus (RN) of rat decreased apomorphine-induced stereotypy, increased haloperidol-induced catalepsy, reversed apomorphine-induced hypothermy, decreased spiroperidol-induced hypomotility, and BHT-920-induced yawning and penile erection episodes. Moreover, apomorphine antagonized haloperidol-induced catalepsy in the RN-lesioned group. The lesioned animals revealed depleted levels of dopamine and its metabolites in brain areas as well as serotonin and its metabolite. The brain areas analyzed were pyriform cortex, substantia nigra, striatum, enthorinal cortex, and cerebellum. Based on these results, it is very likely that the RN has a complex role in the behavior of rats as a consequence of dopaminergic-serotoninergic changes in the central nervous system.

Animals↗
PubMed1997

Analysis of ion channel expression by astrocytes in red nucleus brain stem slices of the rat.

The red nucleus (RN) has been widely used to study the formation and remodeling of synaptic connections during development and in post-lesion plasticity. Since glial cells are thought to contribute to synaptic plasticity, and information on functional properties of brain stem glia is missing, we analyzed voltage-gated ion channels as well as glutamate receptors expressed by glial cells of the RN. The patch-clamp technique was applied to identified cells in acute brain stem slices of 5- to 12-days-old rats. Based on their pattern of membrane currents, two types of glial cells could be distinguished. A first type was characterized by passive, symmetrical currents. The second population of cells, which was the focus of the present study, expressed a complex pattern of voltage-gated channels. These cells could be labeled with antibodies against glutamine synthetase and S100 beta, suggesting an astroglial origin. Depolarizing voltage steps activated transient and delayed rectifier K+ currents as well as Na+ currents. In addition, a subset of cells expressed Ba2+ sensitive inward rectifier K+ currents activated by hyperpolarization. All "complex" glial cells analyzed possessed ionotropic glutamate receptors of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype, while functional kainate and N-methyl-D-aspartate (NMDA) receptors could not be detected. Receptor activation blocked outward rectifying K+ currents, similar to previous observations in glial cells of the hippocampus and the corpus callosum.

Animals↗
PubMed2001

Deafferentation-induced abnormal neurofilament phosphorylation in red nucleus neurones.

Hippocampal deafferentation has been proposed as a pathogenetic mechanism for neurofibrillary tangle (NFT) formation in human mesolimbocortical dementia. We previously developed a rodent model of hippocampal deafferentation involving bilateral destructive lesions of the ventrotegmental area (VTA), septum of the medial forebrain and entorhinal cortex combined with pharmacological inhibition of serotonin 5-HT2 and dopamine D1 receptors. Unexpectedly, we observed an alteration in phosphorylated neurofilament protein immunoreactivity and argyrophilia in magnocellular neurones of the red nucleus. Here, we determined the neuroanatomical, pharmacological and temporal requirements for this effect on red nucleus neurones. We found that abnormal phosphorylation and argyrophilia were critically dependent on bilateral destruction of the VTA and antagonism of 5-HT2 receptors. Although extensive neurofilament hyperphosphorylation and argyrophilia were observed in red nucleus magnocellular neurones within nine days of treatment, no NFTs were formed and these effects were transitory. Resolution of these cytoskeletal abnormalities was accompanied by increased expression of the calcium binding protein, parvalbumin, suggesting that alterations in intraneuronal calcium levels may modify the deafferentation response.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1981

[Synaptic processes in red nucleus neurons induced in the cat by stimulation of the substantia nigra].

Peculiarities of synaptic processes in red nucleus neurons evoked by stimulation of various parts of substantia nigra and cerebellar interposital nucleus were studied in acute experiments in cats using an intracellular recording technique. Such stimulation is stated to induce mono- and polysynaptic activation of the rubrospinal neurons. Great similarity is found in developing monosynaptic cerebellar and nigral excitatory effects. Convergence of these influences onto the same rubro-spinal neurons is revealed. Functional significance of inputs from substantia nigra to the red nucleus for performance of movements is discussed.

Animals↗
PubMed1980

Effects of red nucleus lesions on forelimb movements in the cat.

The effects of uni- and bilateral lesions of the red nucleus on the ability to retrieve food with a forepaw from food wells of different shape were analyzed. Movements which required the use of distal muscles, e.g. retrieving food from narrow horizontal and vertical tubes, were more affected than movements primarily involving more proximal muscles. A decrease in the digital skill occurred during at least 4 months after the surgery, even in the case of subtotal lesions of the red nucleus. The effects of uni- and bilateral rubral lesions appeared to be essentially similar.

Animals↗
PubMed1984

Glucose utilization is unchanged in red nucleus after axotomy.

Separate series of adult rats were subjected to unilateral high cervical and low thoracic section of the rubrospinal tract and sacrificed 1-30 (cervical series) and 3-100 days (thoracic series) later. Local cerebral glucose utilization ([14C]2-DG method of Sokoloff et al.) was determined in the red nucleus and in the inferior colliculus, nucleus interpositus and sensorimotor cortex of both sides in operates and controls. Although severe atrophy of rubral neurons follows cervical tractotomy while reversible chromatolytic alterations occur after thoracic lesions, glucose utilization did not differ in the red nucleus of operated and control rats. However, glucose utilization increased slightly in the inferior colliculus of all operated animals, a finding of indeterminate significance. The failure of axotomized intrinsic neurons of red nucleus and their surround to show altered glucose utilization stands in sharp contrast to the marked increase which occurs in cranial nerve nuclei after axotomy of their contained extrinsic neurons. The data are held to constitute another indication that there is a fundamental difference in the metabolic responses of extrinsic and intrinsic mammalian neurons to axotomy and may support the contention that, in mammals, the axon reaction of intrinsic neurons is fundamentally different from that of extrinsic nerve cells. This difference may have significance for failure of axon regeneration in mammalian CNS.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

GABAergic mechanisms in the cat red nucleus: effects of intracerebral microinjections of muscimol or bicuculline on a conditioned motor task.

Interneurons in the Red Nucleus (RN) are known to be under cortical control and to exert an inhibitory action, mediated by GABAergic mechanisms, on the main output towards the spinal cord. The effects of discrete injections of a GABA receptor agonist (muscimol) or an antagonist (bicuculline) in the Red Nucleus were tested on a motor task performed by seven cats. The subjects were trained to release a lever with a flexion movement of the forelimb controlled by a reaction time (RT) paradigm. Muscimol as well as bicuculline increased RTs in a dose-dependent manner at doses below 100 ng. However the parameters of the force exerted on the lever were differentially altered by the two drugs. Muscimol increased RTs by slowing down the force change preceding movement as well as slightly delaying its latency. While bicuculline increased drastically the force change latency. It could also speed up the force change velocity for low doses. At higher doses (up to 500 ng) both drugs produced an arrest of the performance either associated with anxiety signs (bicuculline) or dystonic movements of the head followed by body rotations (muscimol). The strong motor impairments as well as the disruption of the conditioned performances following muscimol or bicuculline microinjection in the RN suggest an important functional role for GABAergic interneurons. Under the control of cortical afferences they can modulate rubrospinal activity and participate in the triggering of a conditioned movement.

Animals↗
PubMed1981

Increased glutamate decarboxylase activity in the red nucleus of the adult cat after cerebellar lesions.

Glutamate decarboxylase (GAD)activity, a marker for GABAergic structures, was studied in the cat red nucleus. GAD is more concentrated in the rostral than in the caudal third of the structure. GAD levels were measured after chronic unilateral lesions of the cerebellum. Destruction of the dentate area and of the nucleus interpositus induced increases of GAD in the contralateral but not in the ipsilateral red nucleus. Similar changes also occurred in the denervated nucleus ventralis lateralis (VL) and nucleus ventralis anterior (VA) of the thalamus. Results show that loss of the excitatory cerebellar input could lead to changes in inhibitory GABAergic nerve terminals. This increase may be induced transsynaptically within existing neurons or, more likely, additional GAD-containing nerve terminals may be formed by axonal sprouting.

Afferent Pathways↗
PubMed2002

Discharge characteristics of neurons in the red nucleus during voluntary gait modifications: a comparison with the motor cortex.

We have examined the contribution of the red nucleus to the control of locomotion in the cat. Neuronal activity was recorded from 157 rubral neurons, including identified rubrospinal neurons, in three cats trained to walk on a treadmill and to step over obstacles attached to the moving belt. Of 72 neurons with a receptive field confined to the contralateral forelimb, 66 were phasically active during unobstructed locomotion. The maximal activity of the majority of neurons (59/66) was centered around the swing phase of locomotion. Slightly more than half of the neurons (36/66) were phasically activity during both swing and stance. In addition, some rubral neurons (14/66) showed multiple periods of phasic activity within the swing phase of the locomotor cycle. Periods of phasic discharge temporally coincident with the swing phase of the ipsilateral limb were observed in 7/66 neurons. During voluntary gait modifications, most forelimb-related neurons (70/72) showed a significant increase in their discharge activity when the contralateral limb was the first to step over the obstacle (lead condition). Maximal activity in nearly all cells (63/70) was observed during the swing phase, and 23/63 rubral neurons exhibited multiple increases of activity during the modified swing phase. A number of cells (18/70) showed multiple periods of increased activity during swing and stance. Many of the neurons (35/63, 56%) showed an increase in activity at the end of the swing phase; this period of activity was temporally coincident with the period of activity in wrist dorsiflexors, such as the extensor digitorum communis. A smaller proportion of neurons with receptive fields restricted to the hindlimbs showed similar characteristics to those observed in the population of forelimb-related neurons. The overall characteristics of these rubral neurons are similar to those that we obtained previously from pyramidal tract neurons recorded from the motor cortex during an identical task. However, in contrast to the results obtained in the rubral neurons, most motor cortical neurons showed only one period of increased activity during the step cycle. We suggest that both structures contribute to the modifications of the pattern of EMG activity that are required to produce the change in limb trajectory needed to step over an obstacle. However, the results suggest an additional role for the red nucleus in regulating intra- and interlimb coordination.

Action Potentials↗
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↗
PubMed1981

Quantitative analysis of the neuronal population of the red nucleus of the cat.

There is strong evidence in the literature for a correlation between the two parts of the red nucleus, magnocellular and parvocellular, and different functions. Unfortunately in the cat, the species most studied both physiologically and anatomically, there are no morphological criteria distinguishing the two portions. With quantitative techniques applied to Nissl preparations the neuronal population of the Red Nucleus has been studied in serial sections along the rostrocaudal axis of the mesencephalon of the cat. Statistical analysis of the data revealed a horizontal plane dividing the two portions of the nucleus with a high statistical significance level. This plane lies between the caudal two-thirds and the rostral third of the nucleus. Although in the model two portions can be distinguished, it is not possible to assign to either a single type of neuron, whether or considered in terms of shape or size.

Animals↗
PubMed1986

Modulatory influences of red nucleus stimulation on the somatosensory responses of cat trigeminal subnucleus oralis neurons.

Little is known of the effect of red nucleus (RN) stimulation on somatosensory neurons despite its known anatomic projections to somatosensory relay nuclei. The effect of RN stimulation on the somatosensory responses of trigeminal subnucleus oralis (Vo) neurons was investigated in chloralose- or barbiturate-anesthetized cats. Arrays of bipolar stimulating electrodes were inserted into the contralateral and ipsilateral RN and the contralateral thalamus. Extracellular single-unit recordings were obtained in Vo with tungsten microelectrodes. Neurons in Vo were excited to just suprathreshold by electrical stimulation within their receptive fields. Red nucleus influences were studied by applying 100-ms, 500-Hz conditioning trains to the contralateral or ipsilateral RN 130 ms prior to the peripheral test stimulus. The effect of RN stimulation was also tested on mechanically evoked responses of Vo cells. The somatosensory responses of most cells (70/73) were inhibited after RN stimulation. Some of these cells (15/70) could be antidromically activated from the contralateral thalamus. Stimulation of the RN resulted in excitation followed by inhibition in nine Vo cells. The results suggest that the RN may modulate transmission of somatosensory information through Vo.

Animals↗