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PubMed1994

Newly observed pre-cerebellar neurons in the rat are homologous to neurons in the nucleus conterminalis in man.

After injection of wheat germ agglutinin-horseradish peroxidase into the rat cerebellum, a small number of large neurons were labeled in a narrow area between the pyramidal tract and the inferior olivary nucleus. These labeled neurons are distinct from previously described pre-cerebellar neurons in distribution and neuronal size. Together with the known strong acetylcholinesterase activity in this area, the results of this study show that these neurons comprise a novel pre-cerebellar nucleus, which I have designated 'nucleus subolivaris'. Based upon morphological characteristics, it is likely that this small pre-cerebellar nucleus is the homologue of the nucleus conterminalis in man.

Adult↗

PubMedDate not supplied

[The correlation between changes in cell excitability and synaptic efficiency in posttetanic rearrangements in the cortex].

By calculating correlation coefficient (CC) was revealed the positive linear correlation between the changes of a direct and synaptic components of the pyramidal tract response pointing to the correlation between post-tetanic changes of synaptic efficiency and coincident shifts of cellular excitability. Values of CC calculated at initial stages of the trace process formation decreased afterwards and in an hour after the tetanic stimulation there was no significant correlation between the changes of components. Such temporary specificity in the association of the mechanisms under study permits to suppose the community of intracellular molecular substrate underlying interaction and manifestation of these mechanisms at certain stage of trace organization.

Animals↗

PubMed1985

Experimental amyotrophic lateral sclerosis in the guinea-pig.

In guinea-pigs a diet which was deficient in ascorbic acid provoked neurogenic atrophy of the muscles, degeneration of the anterior horn motor cells and demyelination of the pyramidal tract. Muscles showed a decrease of cytochrome and cytochrome c oxidase. Subcutaneous haemorrhages were also found, particularly around the knee joints. The haemorrhages and the histopathology of the muscles and spinal cord were prevented by a high dosage of ascorbic acid. In animals with an ascorbic acid deficiency, histopathology of muscles and spinal cord were also prevented by L-cysteine, L-methionine and L-hydroxyproline. Subcutaneous haemorrhages were not prevented by these supplements.

Amyotrophic Lateral Sclerosis↗

PubMed1979

Regrowth of severed axons in the neonatal central nervous system: establishment of normal connections.

When pyramidal tract axons are cut in the adult hamster, fibers degenerate in both anterograde and retrograde directions from the lesion. If the same operation is performed on infant hamsters, however, there is massive regrowth of the severed axons via a new brainstem pathway to their appropriate terminal sites in the medulla and spinal cord. In contrast to previous studies, these results suggest that axons in the mammalian central nervous system damaged early in life may regenerate in a functionally useful way.

Age Factors↗

PubMed1978

Supplementary motor area of the monkey: activity of neurones during performance of a learned motor task.

1. Recordings were made of the natural dischages of neurones in the supplementary motor area (SMA) of conscious monkeys trained to perform a stereotyped motor task with either hand. 2. Eighty % of the total population of cells showed modulation of their activity during particular movements of either limb. Two thirds of this group had a similar pattern of modulation regardless of whether the contralateral or ipsilateral hand was used. 3. The number of cells whose activity was related to movements of distal joints was approximately equal to that whose discharges occurred with proximal movements. 4. Only 5% of cells tested sent their axons into the pyramidal tract, and only 15% of units investigated showed responses to passive manipulation of the limbs. The effective afferent input usually was of a rather complex kind. 5. The findings suggest that the discharges of a large number of neurones in SMA are changing during particular movements of either arm, and that only a small number of cells receive afferent sensory input. These results contrast with those obtained in the primary motor area and suggest a different role for SMA the control of movement.

Action Potentials↗

PubMed1993

Vertebral artery section for treating arterial compression of the medulla oblongata. Case report.

A case of a 30-year-old man who showed progressive pyramidal tract signs caused by compression of the left vertebral artery is presented. Initial decompression of the vertebral artery by placing a piece of sponge between the artery and medulla had no long-term effect. The left vertebral artery distal to the origin of the posterior inferior cerebellar artery was then sectioned, decompressing the medulla oblongata. The patient's symptoms improved postoperatively. This is the first reported case of brain-stem compression by an elongated vertebral artery treated by sectioning of the artery.

Adult↗

PubMed1986

Long-term alterations in amino acid-induced ionic conductances in chronic epilepsy.

Extracellular free sodium (Na+)o and calcium (Ca2+)o concentration changes were measured in the rat motor cortex, using ion-selective microelectrodes. During ionophoretic applications of excitatory amino acids, decreases in (Na2+)o and in (Ca2+)o were observed. Ca2+ signals were not or very little modified by applications of tetrodotoxin while Na+ signals were slightly depressed, up to 20%. Laminar profile analysis revealed that, while the magnitude of Na+ signals was rather constant throughout the cortex, Ca2+ signals were largest in upper cortical layers. Lesioning and pharmacological experiments indicated that the corresponding permeabilities were most probably located on apical dendrites of pyramidal tract neurons. The relative amplitude of Na+ and Ca2+ signals induced by the release of the glutamate agonists N-methyl-D-aspartate, quisqualate and kainate and the shape of the laminar profile of such responses indicated that different ionic permeabilities located on different neurons underlie such responses. Similar experiments performed on chronic epileptogenic motor foci in rats indicated that the amino acid-induced ionic responses were altered. The significance of such alterations for epileptogenesis is discussed.

Amino Acids↗

PubMedDate not supplied

Influences of cerebral cortex and cerebellum on the red nucleus of the rat.

The aim of the present work was to investigate the unitary responses of neurons belonging to the magnocellular and parvocellular division of the red nucleus (RN) to stimulation of efferents from motor cortex and cerebellum. In anesthetized rats spontaneous discharges of rubro-olivary (RO) and rubrospinal (RS) neurons were tested for stimulation of motor cortex (CX), pyramidal tract (PT), interpositus (IN) and dentate (DN) cerebellar nuclei. It has been observed that the majority of RO and RS neurons were influenced by stimulation of both IN and DN as well as by activation of CX and PT. These results indicate that (1) a segregation of cerebral and cerebellar afferents to RN of rat does not exist and (2) convergent responses from the same cerebral and cerebellar structures have been observed in a high number of both RS and RO neurons.

Animals↗

PubMedDate not supplied

Catecholamines and serotonin in the area postrema of normal and sodium-depleted dogs.

Sodium depletion, a maneuver that is accompanied by a 14-fold elevation of plasma renin activity (PRA), alters the norepinephrine concentration of the canine area postrema (AP), a circumventricular organ of the 4th ventricle known to be sensitive to circulating angiotensin II. The norepinephrine concentration of the AP after 3 weeks of sodium depletion decreased by 43%, whereas the concentration of epinephrine and dopamine and the activity of phenylethanolamine-N-methyltransferase (PNMT) did not change. In the pyramidal tract (PT) and choroid plexus (CP) catecholamines were present in significantly lower amounts than in the AP; their concentrations were unaffected by sodium depletion in the PT, but in the CP the norepinephrine concentration was reduced. Serotonin was present in the AP but its concentration was unaltered by sodium depletion. These findings provide evidence that sodium depletion produced an alteration in the concentration of norepinephrine of the area postrema without any change in the concentration of epinephrine, dopamine or serotonin.

Animals↗

PubMed2004

Normal brain activation in hemiatrophy due to multiple sclerosis: a functional MRI case study.

Evidence from recent functional magnetic resonance imaging studies suggests that adaptive cortical changes ('plasticity') could participate in the maintenance of function in multiple sclerosis (MS). Here, we addressed the impact of brain atrophy on the pattern of cerebral activation in an MS patient with a relapsing-remitting course. This patient showed mildly disabling hemiparesis of the left side (EDSS 2.0), and corresponding brain hemiatrophy (15% volume reduction) of the right hemisphere. The clinical syndrome was considered to result from a lesion in the corona radiata involving corticospinal fibers. Motor-evoked potential recordings confirmed substantial axonal damage to the pyramidal tract arising from that hemisphere. Irrespective of these asymmetries, normal brain activation was found for hand and foot movements for both brain sides. This demonstrates that brain atrophy itself does not necessarily induce cortical adaptive changes, even if mild disability is present. On the other hand, significantly disabling distinct clinical syndromes e.g. arising from spinal cord lesions may evoke cortical changes irrespective of brain atrophy. This issue has to be studied in longitudinal investigations.

Adult↗

PubMed1999

Micturitional disturbances are associated with impaired breathing control in multiple sclerosis.

STUDY OBJECTIVES: To investigate whether the localization of multiple sclerosis (MS), the duration of the disease, and the level of neurologic functioning in patients with MS predispose them to disturbed breathing control. DESIGN: Case-control study. SETTING: Outpatient pneumology department of a university hospital. PATIENTS: Twenty-three MS patients and 51 healthy control subjects. MEASUREMENTS AND RESULTS: Resting mouth occlusion pressure at 0.1 s after onset of inspiratory effort (P0.1) was measured during the hypercapnic response (HCR) and the hypoxic response (HR) in all subjects. The Kurtzke expanded disability status scale and the functional system score were used to describe the level of neurologic functioning of the MS patients. Predictors of HCR and HR were assessed by multiple regression analysis. Low maximal inspiratory pressure (MIP) values correlated with low resting P0.1 values (r = 0.44; p = 0.05), although in neuromuscular diseases, high resting P0.1 values are usually found to compensate for low MIPs. Detrusor-sphincter dyssynergia (DSD) was the only predictor for lower ventilatory HCR (p = 0.006; r2 = 0.52), lower P0.1 HCR (p = 0.004; r2 = 0.47), lower ventilatory HR (p = 0.04; r2 = 0.28), and lower P0.1 HR (p = 0.04; r2 = 0.10); low MIPs and pyramidal tract involvement had no role. CONCLUSIONS: (1) Impaired control of breathing in some MS patients is related mainly to central defects. (2) DSD is the most important predictor of disturbed ventilatory control, presumably because the micturition and pneumotaxic center are closely related and located in the rostral pons. (3) No relationship with the duration of the MS disease could be demonstrated, which can be explained by the variable course of MS itself.

Adult↗

PubMedDate not supplied

Familial amyotrophic lateral sclerosis with posterior column degeneration and basophilic inclusion bodies: a clinical, genetic and pathological study.

We report an autopsy case of familial amyotrophic lateral sclerosis (FALS). The patient was a Japanese woman with hereditary burden. Family history revealed 12 patients with FALS over four generations. She developed muscle weakness of the proximal part of the upper extremities at age 42, followed by dysarthria, dysphagia, muscle weakness and atrophy in the lower extremities, spasticity, hyperreflexia and Babinski's sign. At age 44, she needed ventilatory support. At age 45, she died of bronchopneumonia. The total duration of the disease was three years and one month. Genetic study showed the absence of a mutation in the Cu/Zn superoxide dismutase-1 gene. Neuropathological examination revealed not only neuronal loss in the upper and lower motor neuron and Clarke's column, but also degeneration of the pyramidal tracts, middle root zone of the posterior column and posterior spinocerebellar tract. Bunina bodies and Lewy body-like inclusion bodies were absent. A few basophilic inclusion bodies were present in the neurons of the brain stem and anterior horn of the lumbar cord. Based on these clinical, genetic and pathological findings with a review of the literature, we concluded that our case was the first reported case of FALS with posterior column involvement and basophilic inclusion bodies.

Adult↗

PubMedDate not supplied

[Organization of neuronal responses in the sensomotor cortex during simultaneous stimulation of brain structures].

It has been found on alert non-immobilized rabbits that paired stimulations of the medical lemniscus, the midbrain reticular formation and the pyramidal tract in different succession cause in the sensorimotor cortex the formation of a temporary connection by the parameters of single unit activity and evoked potentials. The temporary connection is manifested in dynamics of evoked responses and in the change of electrical activity at the moment of usual presentation of the second stimulus, if it is omitted. The inflow of impulse activity by different paths adds some peculiarities to the organization of the temporary connection. The leading role in the given model situation may belong to the non-specific system.

Animals↗

PubMed1980

Manipulatory forelimb movements in normal and pyramidotomized dogs.

Normal and unilaterally pyramidotomized dogs were trained to retrieve food from various test devices to allow an estimation of the importance of the pyramidal tract for forelimb movements. The effects of pyramidotomy were relatively weak on movements which to a least extent required use of distal muscles. They were strongest on movements in which wrist flexion and toes flexion and adduction were necessary to get hold of the food. The latter tasks, however, were also among the most difficult ones for normal dogs. The deficits of movements performed after pyramidotomy were similar as previously found in cats if allowance is made for generally weaker components of distal limb muscles in the dog than in the cat.

Animals↗

PubMed1984

Termination areas of corticobulbar and corticospinal fibres in the rat.

Solution of the cobaltic lysine complex compound injected into the bulbar pyramid was taken up by pyramidal tract (PT) fibres and intraaxonally transported as far rostral as the internal capsule, and as far caudal as segment C4 of the spinal cord. With sulfide-precipitation of the cobalt and silver-intensification of the CoS, terminal branches of corticobulbar and corticospinal fibres could be shown in the following structures: In the pons the medial, ventral and the medial part of the lateral pontine nuclei are supplied with collaterals of PT fibres. The medial pontine nucleus receives contralateral PT fibres as well. The nucleus raphe magnus receives PT fibre collaterals from both sides. In the reticular formation contralateral fibres terminate in n. reticularis pontis caudalis, n. gigantocellularis, n. paramedianus, n. reticularis ventralis and dorsalis. Ipsilateral fibers terminate in the n. gigantocellularis and n. reticularis ventralis. The inferior olive receives both ipsilateral and contralateral PT fibres. All parts of the central gray substance are supplied by ipsi-and contralateral fibres which emerge from the PT at the level of the pyramidal decussation. The caudal nucleus of the spinal nucleus of the trigeminus receives a strong bundle of crossing PT fibres which terminate in the subnucleus magnocellularis. The dorsal column nuclei are virtually outlined by the numerous terminals of PT fibres. An oval area at ventrolateral aspect of the cuneate nucleus is innervated by PT fibres. The neurones of this area send their axons to the dorsal white column. In the spinal cord PT fibre terminals delineate four areas of termination. The first is the internal basilar nucleus which is the most richly supplied. The second lies lateral and ventral to this nucleus including segments of laminae V, VI, and VII. The third area extends into the ventral horn including a small zone of the ventral part of lamina VII. Thin PT fibre collaterals may establish here direct contacts with motoneurone dendrites. The fourth area includes laminae III and IV and receives individual terminal formations of thicker PT fibres. Findings which corroborate and which extend previous results are discussed. A few notes are made on the functional significance of some of these fibre connections.

Animals↗

PubMed1994

[Transcranial magnetic stimulation].

The technique of transcranial magnetic stimulation of the motor cortex is a new neurophysiological examination of the central motor pathways. In clinical application a reduced MEP/M wave amplitude ratio had a higher correlation with hyperreflexia than did a delayed MEP onset latency. The inhibitory period (IP) which is a transient suppression of muscle action potentials following motor evoked potentials (MEP) by magnetic cortical stimulation is caused primarily by inhibitory process in the motor cortex, because the duration of IP did not depend on the amplitude of MEPs, MEP distribution over the motor cortex or severity of voluntary contraction. Furthermore, the IP was shorter and the amplitude of MEP was increased when ipsilateral motor cortex stimulation to the thenar muscle preceded the contralateral cortex stimulation. C response in a patient with familial essential myoclonus was significantly suppressed by the magnetic stimulation of the sensory cortex locally and during the IP. The uncrossed pyramidal tract was proved by motor cortex stimulation in a patient with hemorrhage in the right thalamus and internal capsule who showed a right hemiparesis. The enhancement of cortical SEP amplitudes (P23 and N30) were noted when the median nerve was stimulated at 50 msec following magnetic stimulation over the sensory cortex locally. SEPs by twin coil stimulation at thoracic and lumbar root levels are useful in detecting the lesions of spinal cord or roots. Sympathetic skin responses and sudomotor potentials are recorded easily by the neck magnetic stimulation, and are useful method for evaluating sympathetic nerve function.

Cerebral Cortex↗

PubMed1986

Pyramidal input to the basal ganglia in the cat.

In cats with mesencephalic decerebration sparing the cerebral peduncles and ablation of sensorimotor cortex, changes in firing of single neurons of caudate nucleus (CD), putamen (PU), globus pallidus (GP) and entopeduncular necleus (EN) were studied following stimulation of the ipsilateral medullary pyramidal tract (MPT). Cells in CD and PU were not extensively influenced by impulses backfired from MPT (14.7% and 18.7%, respectively). Conversely, a larger number of GP cells (28.1%) and especially EN cells (46.9%) exhibited pronounced changes in their firing following MPT stimulation. The MPT-induced effects on CD and PU were either inhibition or excitations, the latter appearing at latencies greater than 11 ms. The responses observed in GP and EN cells were most frequently excitations, some of which appeared with latencies below 5 ms.

Afferent Pathways↗

PubMed1967

The laminar organization of dorsal horn and effects of descending impulses.

1. An examination of the physiological properties of cells in cat lumbar dorsal horn shows that there are three horizontal laminae which correspond approximately to Rexed (1952) laminae 4, 5, and 6.2. A summary diagram (Fig. 9) suggests the relation of the laminae to each other and to afferent and descending fibres. All three laminae respond to cutaneous stimulation but only lamina 6 responds to movement. By comparing responses of cells in decerebrate and spinal preparations, it is shown that the brain stem inhibits cutaneous responses and enhances movement responses. Pyramidal tract stimulation affects cells in laminae 4, 5, and 6.3. Cells in lamina 4 have small cutaneous receptive fields and respond as though many different types of specific cutaneous afferents converge on them. Cells in lamina 5 respond as though many cells of lamina 4 converge on them. In the decerebrate animal the responses of lamina 5 cells habituate to repeated light pressure stimuli but the cells remain responsive to new stimuli in other parts of their receptive field. Impulses descending from the brain stem can switch the modality of lamina 6 cells from cutaneous to proprioceptive.

Animals↗