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PubMed1995

Occipital cortico-pyramidal projection in hypothyroid rats.

It is well established that the progressive disappearance of a transient occipito-spinal projection in neonatal rats involves the selective elimination of axonal collaterals. We studied whether the development of the occipito-spinal pathway was affected by hypothyroidism induced by treatment with the goitrogen 6n-propyl-2-thiouracil (PTU) beginning prenatally. Using both anterograde (biocytin and Dil) and retrograde (horseradish peroxidase and Fast Blue) tracing techniques in adult hypothyroid rats, we found that many cells with projections into the pyramidal tract are present in regions of visual cortex that are devoid of such cells in normal adult rats. Our results suggest that hypothyroidism induced by PTU treatment leads to the maintenance of occipito-spinal projections that are normally transient.

Animals↗

PubMed2005

Characterization of efferent projections of chemosensitive neurons in the caudal parapyramidal area of the rat brain.

The caudal parapyramidal area of the rat brain contains a population of neurons that are highly sensitive to an increase in the extracellular hydrogen ion concentration ([H+]o). Some of them fire synchronously with respiration when [H+]o is increased. These chemosensitive neurons are located in the caudal ventrolateral medulla in a medial region, closest to the pyramidal tract, and a lateral region, beneath the lateral reticular nucleus. To assess the nature of medullary connections, biotinylated dextran amine injections were performed after recordings from the neurons had been completed. The injections were located within the areas containing serotonergic neurons of the caudal parapyramidal area. The injections within the medial and lateral parts of the caudal parapyramidal region revealed bilateral terminal fields of varicosities within the nucleus of the solitary tract and the ventral respiratory column. Efferent bilateral projections to the lateral paragigantocellular, lateral reticular, and inferior olive nuclei, as well as ipsilateral projections to medial and lateral caudal parapyramidal regions were also identified. Efferent projections towards the raphe obscurus from both medial and lateral caudal parapyramidal regions were found. Medial caudal parapyramidal regions also sent efferent projections towards the raphe pallidus, B1-B3 region, and to the dorsal and ventral parts of the medullary reticular nuclei. The detection of H(+)-sensitive neurons in the caudal parapyramidal area and their projections towards the nucleus of the solitary tract and to the ventral respiratory column, associated with respiratory regulation, indicate that this region could be an excellent candidate for central chemoreception.

Animals↗

PubMed1979

Ortho-antidromic latency fitting and identification of antidromically activated CNS long-axoned neurones.

The intrinsic errors of the collision test were evaluated in extracellular recordings of cat's pyramidal tract (PT)-units. A modified collision technique by means of paired and suitably timed PT-stimuli allowed the demonstration of the ortho-antidromic latency fitting. This method could represent an important counterproof to the true antidromic activation of CNS long-aconed neurons.

Action Potentials↗

PubMed1984

An intracellular study of descending and non-cutaneous afferent input to spinocervical tract neurones in the cat.

Previous studies of input on to spinocervical tract neurones have been extended by investigating the post-synaptic actions of non-cutaneous afferent fibres and of descending tracts on to these neurones, using intracellular recording. In particular, actions of group II muscle, joint and Pacinian afferent fibres and rubro- and corticospinal tract fibres were investigated. Group II muscle afferent fibres evoked excitation and inhibition at a minimal latency compatible with a disynaptic linkage. Increasing the stimulus strength to include group III afferent fibres enhanced these post-synaptic actions only modestly. Inhibition was evoked less frequently and/or required trains of stimuli. Weak stimulation of the interosseous nerve evoked short latency (disynaptic) inhibition or excitation, the latter less frequently. Post-synaptic potentials evoked below threshold for group III afferent fibres of the interosseous nerve are attributed to the actions of Pacinian corpuscles. Low threshold joint afferent fibres evoked excitation at short latency. Higher threshold joint afferent fibres usually evoked inhibition at longer latency, although high threshold excitation was sometimes observed. Stimulation of the pyramidal tract evoked constant latency, unitary e.p.s.p.s which followed high frequencies. The evidence suggests that such e.p.s.p.s are evoked monosynaptically. Polysynaptic excitation and inhibition were also observed. No convincing evidence could be found of actions evoked directly by the rubrospinal tract, although actions mediated via other descending systems could be induced from the red nucleus. A large degree of convergence was seen from different peripheral and descending systems on to individual neurones.

Action Potentials↗

PubMed1984

Neuroanatomical status of monkeys showing functional compensation following neonatal cerebellar lesions.

Neuroanatomical changes observed at the light microscopic level in various brain areas of four adult monkeys, who had various degrees of cerebellar ablation shortly after birth, are described in this study. Extensive neonatal hemilateral ablations of the cerebellar cortex (sparing the nuclei), which have previously been shown to leave the adult monkey with no discernible motor deficits, lead to substantial degeneration, mainly within the remaining cerebellum and the brain stem. In particular: 1) Ipsilateral to the lesion the intracerebellar nuclei and to some extent also the lateral vestibular nucleus are clearly reduced in size, whereas the contralateral cerebellum appears normal. 2) The principal olive and parts of the pontine nuclei show massive degeneration contralateral to the lesion. 3) Among the nuclei efferent to the cerebellum only the red nucleus contralateral to the lesion shows clear signs of degeneration. 4) Morphometric analysis of motor cortex and pyramidal tract reveals no systematic differences between the left and right sides, nor any other morphological indication of compensation. The morphological abnormality pattern in our monkeys is particularly similar to that described in cases of humans with olivo-pontocerebellar atrophies.

Animals↗

PubMed2001

Spatiotemporal distribution of GAP-43 in the developing rat spinal cord: a histological and quantitative immunofluorescence study.

In the rat spinal cord we studied developmental changes in spatiotemporal expression of the growth-associated protein GAP-43, which is known to play an important role in neural development, axonal regeneration, and modulation of synaptic function. GAP-43 was expressed predominantly in the white matter at embryonic day 13 to postnatal day 7, evenly in the white and gray matter at the 2nd to the 3rd postnatal week, and predominantly in the gray matter after the 5th postnatal week. The shifting of predominance was quantitatively assessed. On the basis of histological findings and quantitative assessment of GAP-43 immunoreactivity, it appears likely that the development proceeds from the phase of mostly axonal elongation during the embryonic period and the 1st postnatal week, via the phase of axonal elongation and formation of end arbors and synaptic organization during the 2nd to the 4th postnatal week, to the phase of final maturation of synaptic organization. GAP-43 was continuously expressed through adulthood in neuropil of the gray matter, the pyramidal tract, and the dorsal portion of the lateral funiculus that was identified as serotonergic by confocal laser scanning microscopic studies. The continuous expression may imply perpetual remodeling in these structures even in adulthood.

Animals↗

PubMed1990

[The characteristics of the synaptic reorganization in the sensorimotor cortex of cats after the destruction of the symmetrical portion of the cortex in the opposite hemisphere].

Intracellular recording technique has been used to study reactions of corticospinal neurons (CSN) to stimulation of the ipsilateral ventrolateral nucleus (VLN) of the thalamus in acute experiments on adult intact cats and on cats after lesion on the contralateral sensorimotor cortex (exposition from 6 months to 1.5 years). Acceleration of the monosynaptic EPSPs rise phase in slow CSN was revealed in operated animals, which presumed the reorganization of the synaptic contacts in the SD membrane of flow CSN. Detailed analysis of features and branching of CSN axon, collaterals passing to VLN of the thalamus and participating in formation of the ipsilateral pyramidal tract was made by the method of collision test. The significance of the plastic synaptic reconstruction in the ipsilateral thalamo-cortex reverberating system during the outflow formation under conditions of the partial cortex interhemisphere deafferentation is discussed.

Animals↗

PubMed2005

Motor cortical modulation of cutaneous reflex responses in the hindlimb of the intact cat.

We have used the technique of spatial facilitation to examine the interactions between the signals conveyed by the corticospinal tract and those of cutaneous afferents in the hindlimb of the intact, walking cat. Microstimulation was applied to 20 cortical sites in the hindlimb representation of the motor cortex and to three different cutaneous nerves innervating the hindpaw in four cats. Conditioning stimuli to the motor cortex induced both facilitation and depression of cutaneous reflexes evoked by stimulation of nerves in the hindlimb contralateral to the cortical stimulation site. Facilitation was most frequently evoked by conditioning stimuli in the range of 10-30 ms before the cutaneous stimulation; depression was normally evoked by shorter and longer conditioning delays. Similar changes were observed after conditioning stimuli to the pyramidal tract, suggesting that the changes were independent of any changes in cortical excitability. Modulation of reflex activity varied according to the muscle under study, the cutaneous nerve used to evoke the reflex and the cortical site used to condition the reflex. Together, these results suggest that there is spatial convergence of corticospinal and cutaneous afferent activity and that this convergence is mediated by distinct subpopulations of spinal interneurons.

Animals↗

PubMed1991

Striatopallidonigral degeneration in Pick's disease: a clinicopathological study of 41 cases.

The frequency and degree of stiatopallidonigral (SPN) degeneration were examined in 41 autopsy cases of Pick's disease. Based on the degree of SPN degeneration, these cases were arranged into four groups: 1) group I (severely degenerate; 19.5%), 2) group II (moderately degenerate; 22.0%), 3) group III (mildly degenerate; 36.5%), and 4) group IV (non-degenerate; 22.0%). 17 of the 41 cases had a definite (moderate to severe) SPN degeneration. The striatum, especially the caudate nucleus, was most frequently and most severely affected, while the internal segment of the globus pallidus was least frequently and least severely affected. In general, the oral portions of the SPN nuclei were more severely involved. In addition, in the putamen and globus pallidus the dorsomedial portions adjacent to the internal capsule were apt to be affected more markedly than the other portions. In the substantia nigra the degeneration tended to be more predominant in the pars reticulata than in the pars compacta, although both were usually involved. In addition, the medial to central portions of the substantia nigra were more vulnerable. In comparing the severely and moderately degenerate groups (groups I and II) with the mildly and non degenerate groups (groups III and IV), the former had more female cases, longer duration of illness, and more third-stage cases. In addition, the former contained more cases with lower brain weight and (predominant) frontal atrophy type, and more atypical cases without Pick bodies, or with symmetrical pyramidal tract degeneration or with combined traumatic lesions. It is notable that in all cases with definite SPN degeneration no extrapyramidal involuntary movements had been detected.

Adult↗

PubMed1994

MRI abnormalities in Behr syndrome.

The etiology of Behr syndrome remains uncertain. A 6-year-old girl with a progressive syndrome of optic atrophy, ataxia, myoclonic epilepsy, urinary incontinence, and pyramidal tract degeneration suggestive of Behr syndrome is described. Diffuse, symmetric white matter abnormalities were demonstrated by magnetic resonance imaging suggesting that Behr syndrome may represent a disorder of white matter associated with an unknown biochemical abnormality.

Brain↗

PubMed1987

Beta-receptor-mediated increase in cerebral blood flow during hypoglycemia.

We tested the hypothesis that beta-adrenergic receptor stimulation is involved with the increase in regional cerebral blood flow (rCBF) during hypoglycemia. Rats were surgically prepared with the use of halothane-nitrous oxide anesthesia. A plaster restraining cast was placed around the hindquarters, and anesthesia was discontinued. Hypoglycemia was produced by an intravenous injection of insulin (15 U/kg); normoglycemic control rats were given saline. Propranolol (1.5 mg/kg) was administered to some control and some hypoglycemic rats to block the beta-adrenergic receptors. Regional CBF was measured using 4-[N-methyl-14C]iodoantipyrine. Plasma glucose in the normoglycemic and hypoglycemic groups was approximately 6 and 1.4 mumol/ml, respectively. Regional CBF increased during hypoglycemia in rats that were not treated with propranolol. The increase varied from approximately 60 to 200% depending on the brain region. During hypoglycemia, propranolol abolished the increase in rCBF in the hypothalamus, cerebellum, and pyramidal tract. In other regions the increase in rCBF was only 33-65% of the increase in hypoglycemic rats that were not treated with propranolol. We conclude that beta-receptor stimulation plays a major role in the increase in rCBF during hypoglycemia.

Animals↗

PubMed1993

Reduced isotope uptake restricted to the motor area in patients with amyotrophic lateral sclerosis.

To study degeneration in the central nervous system in amyotrophic lateral sclerosis (ALS), we studied four patients using single photon emission tomography (SPECT) and magnetic resonance imaging (MRI). MRI demonstrated high intensity along the pyramidal tract on T2-weighted images in two. SPECT demonstrated reduced isotope uptake restricted to the motor area. While the cause of degeneration of the cortical neurons in the motor area is unknown, SPECT is useful for detecting the degeneration in patients with ALS.

Amyotrophic Lateral Sclerosis↗

PubMed1984

[Synaptic plasticity at the levels of the archicortex and neocortex].

A review of the author's studies of properties and mechanisms of long-term potentiation (LTP) is presented. LTP of field potentials and neuronal responses at hippocampal CA1 and CA3 regions of unanaesthetized rabbit was found. Excitatory and inhibitory post-synaptic potentials increased after tetanization. Microiontophoretic and histochemical studies revealed no appropriate changes in acetylcholine sensitivity or in acetylcholinesterase activity to explain LTP. Quantal analysis of EPSP evoked by microstimulation indicated increase in the number of transmitter quanta released by a presynaptic spike. LTP of field potentials evoked by white matter stimulation at neocortical slices and sensorimotor cortex of unanaesthetized rabbit are described. Changes in short-latency neuronal responses and "indirect" component of pyramidal tract response suggest monosynaptic LTP at neocortex. It is concluded that the main mechanism of both hippocampal and neocortical LTP consists of an increase in efficacy of excitatory synapses. It is suggested that these synapses are used in learning and memory processes.

Acetylcholine↗

PubMed1989

Postnatal development of the corticospinal tract in the rat. An ultrastructural anterograde HRP study.

Horseradish-peroxidase was used to anterogradely label and thus to trace the growth of corticospinal axons in rats ranging in age from one day to six months. Three to eight HRP-gels were implanted in the left cerebral hemisphere of the cortex. In each spinal cord three levels were studied, the cervical intumescence (C5), the mid-thoracic region (T5) and the lumbar enlargement (L3). The methodology employed for the electron microscopic visualization of HRP has been described previously (Joosten et al. 1987a). The outgrowth of labelled unmyelinated corticospinal tract axons in the rat spinal cord primarily occurs during the first ten postnatal days. The outgrowth of the main wave of these fibres is preceded by a number of pathfinding axons, characterized by dilatations at their distal ends, the growth cones. By contrast, later appearing unmyelinated axons, which presumably grow along the pathfinding axons, do not exhibit such growth cones. The first labelled pioneer axons can be observed in the cervical intumescence at postnatal day one (P1), in the mid-thoracic region at day three (P3) and in the lumbar enlargement at day five (P5). Prior to the entrance of the axons, the prospective corticospinal area or the pre-arrival zone is composed of fascicles consisting of unlabelled, unmyelinated fibres surrounded by lucent amorphous structures. During the outgrowth phase of the corticospinal fibres some myelinated axons could be observed within the outgrowth area even before day 14. These axons, however, were never labelled. These findings strongly suggest that the outgrowth area, which is generally denoted as the pyramidal tract, contains other axons besides the corticospinal fibres (and glial cells).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1998

Fast corticospinal system and motor performance in children: conduction proceeds skill.

Transcranial magnetic stimulation and motor performance tests were used to study the correlation between corticospinal maturation and actual motor performance in a group of young school children (n = 10, mean age = 7 years, age range = 6-9 years). The results were compared with normal adults (n = 10, mean age = 24 years, age range = 22-26 years). In children the central conduction time under the preinnervation condition of facilitation and the postexcitatory silent period was similar to that in adults. However, the central conduction time under relaxation, the latency jump (defined as the difference between the two preinnervation conditions), and the stimulus intensity were statistically different between children and adults (P < 0.01-0.001). Children did not reach the same level of performance as adults in any of the motor performance tasks (simple acoustic reaction time, tapping, ballistic movement, tracking, and diadochokinesis) (P < 0.05-0.01). The results indicate that at an early school age, children already possess mature fast corticospinal pathways able to access spinal motoneurons through the pyramidal tract. However, despite the partially adult-like level of neuronal maturation, young school children were not able to perform deliberate motor actions with the same proficiency as adults.

Adult↗

PubMed2003

Babinski-Nageotte's syndrome and Hemimedullary (Reinhold's) syndrome are clinically and morphologically distinct conditions.

A hemimedullary infarction, in which medial and lateral medullary lesions occur simultaneously, is a rare cerebrovascular disease. It has been suggested that the Babinski-Nageotte's syndrome is the classical brainstem syndrome that corresponds to hemimedullary lesion. In this study we compare clinical symptoms and magnetic resonance imaging (MRI) data of two patients exhibiting classical Babinski-Nageotte's syndrome according to the original description with symptoms and MRI data of a patient with clinically complete hemimedullary lesion. Our study shows that Babinski-Nageotte's syndrome is neither clinically nor on MRI identical with hemimedullary lesion. Hypoglossal palsy, an invariable symptom of hemimedullary syndrome, is not part of the Babinski-Nageotte's syndrome according to the original description. Consistent with the original historical report, Babinski- Nageotte's syndrome is a lateral "Wallenbergian" medullary lesion with a spreading of the lesion to the more basal localised pyramidal tract. The clinical features of the hemimedullary syndrome, described in 1894 by Reinhold, and the MRI appearances in our patient with this syndrome are clearly different from other classical brainstem syndromes and should be called Reinhold's syndrome.

Adult↗

PubMed1973

Neurological disease associated with folate deficiency.

In a general medical hospital population the neurological status of 24 patients with severe folate deficiency was compared with that of a control group of 21 patients with normal serum folate. A significant increase of organic brain syndrome and pyramidal tract damage was found in the folate-deficient group. These findings were independent of the degree of anaemia or the presence of alcoholism. These data are consistent with the view that severe folate deficiency may cause neurological deficits.

Alcoholism↗

PubMed2005

[Can diffusion tensor imaging predict the functional outcome of supra-tentorial stroke?].

We used diffusion tensor imaging (DTI) to assess wallerian degeneration of the pyramidal tract after the onset of supra-tentorial stroke, and correlation of the extent of Wallerian degeneration with the motor function at 3 months after stroke. Twenty eight patients with supra-tentorial acute stroke were examined, two weeks and one month after stroke by DTI. We measured fractional anisotropy(FA) of affected side/ unaffected side (FA ratio) in the cerebral peduncle. We used modified Rankin Scale (mRS) for assessment of motor function at 3 months after stroke. FA ratio was significantly reduced at 2 weeks after stroke (0.833 +/- 0.146) compared to on admission (0.979 +/- 0.0797). But no significant change of FA ratio was seen between two weeks and one month after stroke in 7 cases examined (0.758 +/- 0.183 vs. 0.754 +/- 0.183). In all patients in whom the FA ratio was under 0.8 at 2 weeks after stroke, motor function showed poor recovery (mRS 4 and 5) at 3 months after stroke. When FA ratio was over 0.8 at 2 weeks after stroke, motor function at 3 months after stroke showed good recovery (mRS 0 to 3) expect for three elderly patients. With the use of DTI, Wallerian degeneration could be detected in the corticospinal tracts at midbrain level during the early phase of supra-tentorial stroke. We conclude that DTI may be useful for early prediction of motor function prognosis in patients with supra-tentorial acute stroke.

Adult↗