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Showing papers on "Motor neuron published in 1981"


Journal ArticleDOI
TL;DR: In histograms prepared from seven cases of amyotrophic lateral sclerosis (ALS), the Cl and Al peaks were decreased selectively and severely, providing evidence for alpha, but not gamma, motor neuron vulnerability.
Abstract: The diameter histograms of cell bodies (cytons) in motor neuron columns at the L5 segment of the spinal cord of adult man reproducibly yield three peaks of increasing height: small (Cs), intermediate (Ci), and large (Cl). Histograms of L5 myelinated axons obtained from the ventral root have two peaks of increasing height: intermediate (Ai) and large (Al). In histograms prepared from seven cases of amyotrophic lateral sclerosis (ALS), the Cl and Al peaks were decreased selectively and severely. This provides evidence for alpha, but not gamma, motor neuron vulnerability. The Cl peak of spinal ganglion neurons and the Al peak of dorsal roots were significantly reduced in number, without a concomitant increase in Ci, Cs, and Ai peaks. This, plus earlier reports of abnormal cutaneous sensation thresholds, abnormal rates of fiber degeneration in cutaneous nerves, and dorsal column demyelination, provides evidence that large afferent neurons are affected in ALS, but to a lesser degree than alpha motor neurons.

206 citations


Journal ArticleDOI
TL;DR: It is found that decrement in MND relates to activity of disease of the motor neuron, and the mean amplitude of the compound muscle action potential was significantly lower in both the rapid-disease and slow-Disease groups than in controls.
Abstract: we found significant decrement of the compound muscle action potential recorded from the abductor digiti minimi muscle in response to repetitive nerve stimulation in patients with rapidly developing motor neuron disease (MND), but not in patients with slowly developing disease when measured before exercise (7.6 ± 1.3% versus 1.6 ± 1.6%) and 2 minutes after exercise (13.6 ± 1.2% versus 0.5 ± 0.5%). All patients showed repair of decrement immediately after exercise. The mean amplitude of the compound muscle action potential was significantly lower in both the rapid-disease (2.9 ± 0.9 mV) and slow-disease (5.2 ± 1.6 mV) groups than in controls (14.5 ± 1.2 mV). For individual patients, there was no correlation between amplitude of the compound muscle action potential and decrement. These data indicate that decrement in MND relates to activity of disease of the motor neuron.

107 citations


Journal ArticleDOI
TL;DR: The present study suggested that the site of the primary lesion seems to be in the α-motoneuron fibers in motor neuron diseases, such as ALS or SPMA, and the marked discrepancy in the pathologic change in theα-mot oneuron fibersIn the VSR and the nerve roots innervating the external ocular muscles was noteworthy.
Abstract: Amyotrophic lateral sclerosis (ALS) and adult onset X-linked recessive bulbospinal muscular atrophy (SPMA), constituting the category of adult onset form of motor neuron disease, were analyzed on motor nerve roots. The results of morphometric analysis on ventral spinal roots (VSR) of all spinal segments from ALS and SPMA revealed the following three findings: (1) the large-myelinated α-motoneuron fibers were markedly decreased in number throughout all segments; (2) thin-myelinated autonomic preganglionic fibers were almost completely preserved; (3) small-intermediate-myelinated fibers which are considered to correspond to γ-motoneuron fibers were generally well preserved in ALS, but decreased by one-half to one-third in SPMA. However, all the components of the nerve roots of the oculomotor, trochlear, and abducent nerves were completely preserved in both ALS and SPMA. Moreover, the teasedfiber study showed that the regenerating-sprouting process rarely occurred in the VSR of ALS and SPMA. The present study suggested that the site of the primary lesion seems to be in the α-motoneuron fibers in motor neuron diseases, such as ALS or SPMA. However, the marked discrepancy in the pathologic change in the α-motoneuron fibers in the VSR and the nerve roots innervating the external ocular muscles was noteworthy.

57 citations


Journal ArticleDOI
TL;DR: The results suggest that atrophy and loss of such proximal elements cannot be explained by acute distal pathology, but could be the result of chronic disorders, particularly when severe.
Abstract: Morphometric assessment of the size distribution of cell bodies (cytons) in motor neuron columns from serial sections of lumbar spinal segments reproducibly yields three peaks. Using troughs between peaks as division points, it is possible to determine the number of large (Cl), intermediate (Ci), and small (Cs) cytons per lumbar segment. In a patient with above-knee amputation 4 1/2 years previously, the number of Cl was 42%, Ci 99%, and Cs 129% that of normal. Nine years after total amputation of a lower limb for chondrosarcoma, a second patient exhibited values of 25%, 14%, and 55%, respectively. Normal results were obtained from the non-amputated sides. These results, and our previous studies on the permanent axotomy model, show that loss of target tissue by axotomy leads to atrophy and then loss of motor neurons. Extrapolated to the interpretation of morphologic abnormalities of proximal neuronal alterations in peripheral neuropathy, these results suggest that atrophy and loss of such proximal elements cannot be explained by acute distal pathology, but could be the result of chronic disorders, particularly when severe.

52 citations


Journal ArticleDOI
TL;DR: It is proved that this scheme will transform the initial pattern of innervation into one in which each muscle fibre has contact from a single axon, subject to the total survival strength available to each motor neuron remaining constant.
Abstract: An analysis is given of the polyneuronal innervation of embryonic skeletal muscle and its subsequent elimination during development. The amount of polyneuronal innervation that has been observed is consistent with the notion that initially each motor neuron distributes its contacts at random among the available fibres of a particular muscle. The idea that the elimination of excess innervation proceeds through interactions between terminals is placed on a quantitative basis. Each motor neuron is presumed to have a finite capacity for maintaining the structure and activity of its terminals, which is shared out among them; a survival strength can be assigned to each terminal. Survival strengths undergo a process of continual adjustment. A terminal with above average strength for its endplate is strengthened at the expense of the weaker terminals, subject to the total survival strength available to each motor neuron remaining constant. It is proved that this scheme will transform the initial pattern of innervation into one in which each muscle fibre has contact from a single axon. Interpretations of the following results are given: the decrease in the spread of motor unit size during the development of innervation of the rat soleus muscle; the time course of superinnervation; the effects of neonatal partial denervation. Various suggestions are made for future experimental approaches.

40 citations


Journal ArticleDOI
TL;DR: The importance of the observation lies in the more precise localisation voltage source for "M" response in terminal or near-terminal carpal tunnel median nerve entrapments and avoidance of possible misinterpretation of electrophysiological observations in this most common nerve ent Trapment syndrome.
Abstract: At late stages of median nerve entrapment in the carpal tunnel there may be total denervation of the thenar muscles. Surface electrodes over the thenar endplate zone may record an initial and predominantly positive "M" response to supramaximal median nerve stimulation. By a combination of techniques, it has been established that this surface positive response originates from surviving lumbrical muscles innervated by the median nerve. Their relative preservation may be related to their location in the median nerve. Intraoperative investigations have shown that the thenar motor fibres are primarily located in the ventral-lateral part of the median nerve whereas lumbrical motor fibres are in a more dorsal location and hence are probably better protected against the flexor retinaculum. This relative preservation of lumbrical motor fibres has been observed in other peripheral neuropathies and motor neuron disease, but not in median nerve regeneration of the following nerve transection. The importance of the observation lies in the more precise localisation voltage source for "M" response in terminal or near-terminal carpal tunnel median nerve entrapments and avoidance thereby of possible misinterpretation of electrophysiological observations in this most common nerve entrapment syndrome.

38 citations


Journal ArticleDOI
TL;DR: The number of neurons in motor neuron pools to different limb muscles were determined during development using horseradish peroxidase and each showed a similar percentage decline of 45% in cell numbers during the first postnatal week.

35 citations


Journal ArticleDOI
TL;DR: The topographical projection of segmental nerves 8 and 9 to the glutaeus muscle of developing frogs was determined during the motor neuron death period and the emergence of this mature innervation pattern is accompanied by motor neurons death, with which it may be causally related.

35 citations


Journal ArticleDOI
TL;DR: While some general features of organization of these reflexes are common, specific differences have developed that contribute to differences in the expression of the two behaviors.
Abstract: 1. Defensive inking behavior and gill withdrawal in ApIysia offer simple test systems in which the cellular and biophysial determinants of elementary behavioral acts can be examined. Since a good deal is known regarding both the behaviors and their underlying neural circuits, it is possible to compare directly these two defensive reflexes at the cellular level. 2. Both the ink and gill motor neurons are activated by tactile or electrical stimulation of the mantle region. At least part of the sensory input is mediated by previously identified LE, RE, and RF cluster sensory neurons (4, 6). Some sensory neurons make direct monosynaptic connections to both gill and ink motor neurons. 3. In addition to the monosynaptic pathway, both types of motor neurons receive polysynaptic input. R 18 is an example of one excitatory interneuron that produces fast excitatory postsynaptic potentials (EPSPs) in both ink motor neuron L14 and gill motor neuron L7. 4. Tactile stimulation of the skin also excites a cluster of at least three interneurons, one of which has been identified as L31. L31 produces a slow decreased conductance EPSP in ink motor neuron L14 but appears to make no connection to gill motor neuron L7. 5. In addition to the excitatory input to ink motor neurons, there is a pronounced slow inhibitory input from a cluster of at least five cells, one of which has been identified as L32. In contrast to the predominant slow inhibition of ink motor neurons, L32 produces predominant fast EPSPs in gill motor neuron L7. 6. Tactile stimulation of the skin inhibits L32 and at least part of the inhibition is mediated by the previously identified interneuron L16 ( 18). L16 is weakly electrically coupled to ink motor neuron L14 but not to gill motor neuron L7. 7. The two circuits utilize common sensory neurons and interneurons and are mediated by both monoand polysynaptic pathways. However, some neurons (L32) have different synaptic actions on each type of motor neuron, others (L3 1) appear to be used for one circuit and not the other, while one neuron (L16) is electrically coupled to ink motor neuron L14 but not to gill motor neuron L7. In addition, the ink motor neurons are electrically coupled while the gill motor neurons are not (9, 11). Furthermore, the ink motor neurons have intrinsic biophysical properties, which contribute to their firing pattern (2, 9, 12). Thus, while some general features of organization of these reflexes are common, specific differences have developed that contribute to differences in the expression of the two behaviors (11, 26).

31 citations


Journal Article
TL;DR: Regions of neurofilamentous degeneration adjacent to and contiguous with filamentous enlargements in areas of neuronal degeneration in the spinal cord were found in six cases of sporadic motor neuron disease (MND).
Abstract: Regions of neurofilamentous degeneration adjacent to and contiguous with filamentous enlargements in areas of neuronal degeneration in the spinal cord were found in six cases of sporadic motor neuron disease (MND). Unusual particles, 28 nm in diameter, were found within the lesions. The lesion might possibly be significant in relation to neuronal degeneration in MND.

22 citations


Book ChapterDOI
01 Jan 1981
TL;DR: In the intact muscles of normal mice, sprouting and synapse formation is an ongoing process which can be enhanced by contralateral axotomy, and the underlying mechanism may be the transneuronal induction of sprouted muscle fibres already innervated by their parent axons.
Abstract: Publisher Summary The pattern of innervation of tissues is characterised by the specificity of connections and the number of synapses that exist between the innervating neurons and their target cells The proper numerical balance of synaptic connections is established during development and maintained throughout life The different mechanisms suggested to be instrumental in the establishment and maintenance of this numerical balance have in common the involvement of a direct mode of interaction (trophic or activity) between the neurons and their target cells The cutaneous-pectoris muscles of the frog are two distinct muscles that lie side by side in the front of the frog's chest Each muscle is supplied by a separate motor nerve whose cell bodies are situated in the spinal cord on the same side as the muscle they innervate Most muscle fibers are innervated by a single motor neuron but about 16% are polyneuronally innervated This normal adult pattern of innervation of intact muscles can be altered

Journal ArticleDOI
TL;DR: In 22 patients with motor neuron disease (MND), the mean concentration of serotonin (5HT) in platelets was slightly increased, platelet monoamine oxidase (MAO) activity was significantly increased, and plasma concentrations of total and both free and bound tryptophan were significantly decreased.
Abstract: • In 22 patients with motor neuron disease (MND), the mean concentration of serotonin (5HT) in platelets was slightly increased, platelet monoamine oxidase (MAO) activity was significantly increased, and plasma concentrations of total and both free and bound tryptophan were significantly decreased. Though platelet MAO activity was positively correlated with concentrations of 5HT, independent causal mechanisms are probable. When patients were rated according to severity, highest values of platelet 5HT and MAO activity were found in the most severely affected group, whereas concentrations of both total and protein-bound tryptophan were most decreased. Changes in concentrations of 5HT and tryptophan may reflect compensatory changes in response to degeneration of motor neurons or to interruption of their monoaminergic innervation.

Journal ArticleDOI
TL;DR: The main dilator motor neuron of the esophageal nervous system (OD I), which has a spike-initiating zone in three different centers, sends an axon into each output nerve of the symmetrical commisural ganglia.
Abstract: 1. The main dilator motor neuron of the esophageal nervous system (OD I), which has a spike-initiating zone in three different centers, sends an axon into each output nerve of the symmetrical commisural ganglia. 2. The somatofugal spikes generated by the esophageal spike-initiating zone of ODl (located in the esophageal ganglion) are rhythmically blocked in the commissural ganglia and regularly fail in the output nerves. 3, The conduction block does not result from the repetitive firing of the ODl axons, as spikes can propagate without block for several seconds at frequencies up to 100 Hz when synaptic activity is blocked in the commissural ganglia. It also does not depend on the discharge of the commissural spike-initiating zones of ODl, and thus does not act as a low-pass filter. 4. However, a slight influence of the geometry of the axons of ODl is shown by the fact that spikes pass through the site of block more easily in the orthodromic direction than in the antidromic one and that for orthodromic spikes the extent of block differs in the different output nerves of a given side. 5. The conduction block in the commissural part of the axons of ODl is essentially synaptically controlled by the oscillators (one in each commissural ganglion) that generate the esophageal rhythm. This is indicated by the fact that the block is temporally related to the esophageal rhythm, that eliminating the synaptic activity of the oscillators suppresses the conduction block, that the block is more extensive on the side of the active esophageal oscillator, and that stimulating the synaptic activity of an oscillator increases the duration of the conduction block. 6. The esophageal oscillators exert a true control on impulse conduction in ODl axons. They not only regularly impede the spike propagation, but also alternately enhance it. 7. Several important functional implications are discussed, among which the most fundamental is that a rhythm generator can induce a rhythmical muscular activity either by phasically stimulating a silent motor neuron or by rhythmically blocking the axonal conduction in a tonically firing motor neuron.

Journal ArticleDOI
TL;DR: The progression of the disease appears to be faster than in spinal muscular atrophy of Wohlfart-Kugelberg-Welander and the descriptive term, 'X-linked spinal and bulbar atrophy' or 'Kennedy-Stefanis disease' is proposed.
Abstract: X-linked spinal and bulbar muscular atrophy of late onset is a rare variety of motor neuron disease. In this report a Greek family with 2 affected brothers is described. It is interesting that all Gre

Journal ArticleDOI
TL;DR: The results support the hypothesis of a neurogenic origin of the skeletal muscle fiber abnormalities that have been reported in psychotic patients.
Abstract: • Excessive branching of subterminal motor nerves and multiple innervation of skeletal muscle fibers were significantly more common in 102 psychotic patients of various diagnostic types than in 23 age-matched normal control subjects. Increased branching of subterminal motor nerves was significantly more common in paranoid schizophrenic patients than in nonparanoid schizophrenic patients and normal control subjects. The results support the hypothesis of a neurogenic origin of the skeletal muscle fiber abnormalities that have been reported in psychotic patients.

Journal ArticleDOI
TL;DR: Findings are evidence of rapid, reversible changes in the nervous system following the trigger for the transformation process in snapping shrimp, as well as an additional neuronal modification early within this period.

Journal ArticleDOI
TL;DR: Filamentous axonalmasses, similar to the abnormal enlargements found in the ventral horns, were found in Clarke’s nucleus in six cases of sporadic A LS, suggesting that this system is also pathologically involved.

Journal ArticleDOI
05 Jun 1981-JAMA
TL;DR: Somatosensory potentials recorded over the head and spinal cord have been useful procedures to evaluate afferent pathways in the CNS and may have prognostic value early in the course of head and spine cord injuries.
Abstract: The United Nations has proclaimed 1981 the International Year of the Disabled, and thus the research and clinical advances in physical medicine and rehabilitation are appropriately highlighted. Diagnosis Single-fiber electromyography has emerged as a clinically useful technique to identify neuromuscular transmission defects at an earlier stage in myasthenia gravis and related diseases. It also has become helpful in the semiquantitative estimation of reinnervation after nerve regrowth and certain motor unit diseases. This technique involves the measurement of variations in latencies of transmission of clinically mediated nerve impulses across the myoneural junction within a given motor neuron. Somatosensory potentials recorded over the head and spinal cord have been useful procedures to evaluate afferent pathways in the CNS. These may have prognostic value early in the course of head and spinal cord injuries and are also being used to monitor the spinal cord in certain operations on the spinal column. Pain Management

Journal ArticleDOI
01 Jan 1981
TL;DR: It is demonstrated that supraspinal nerve influence can modify the axonal transport of ACh and cholinergic enzymes in the rat sciatic nerve, and that descending monoamine pathways may, at least to some extent, participate in this modulation of intraneuronal dynamics in the motor neuron.
Abstract: The content and intra-axonal transport of acetylcholine (ACh) and the ACh-metabolizing enzymes choline-acetyl-transferase (CAT) and ACh-esterase (AChE) in the rat sciatic nerve were studied after various experimental procedures. The procedures involved: (1) spinal cord transection (SCT) at the thoracic level 1 day to 3 weeks prior to experiments, to abolish nerve activity of the lower motor neurons (in the lumbar intumescence-sciatic nerve) from supraspinal centres; (2) physical training for 2 h daily during 2 weeks in a rodent treadmill, to increase nerve activity from supraspinal levels; and (3) the use of selective neurotoxins to cause degeneration of descending bulbospinal monoaminergic (MA) neurons. The results of these studies demonstrate that supraspinal nerve influence can modify the axonal transport of ACh and cholinergic enzymes in the rat sciatic nerve, and that descending monoamine (MA) pathways may, at least to some extent, participate in this modulation of intraneuronal dynamics in the motor neuron. Since it has been shown by many investigators that factors which have a trophic influence on skeletal muscle cells both in vitro and in vivo are present in motor nerves and transported along the axons in a distal direction, we suggest that the synthesis and axonal transport of such factors may also be under control of supraspinal nerve activity. Therefore, it is possible that metabolic changes and dystrophy of muscles occurring in patients with lesions of the 'upper motor neuron-type' may also, in addition to other factors, be dependent on changes in intra-axonal transport of various substances in the lower motor neuron.


Journal ArticleDOI
TL;DR: A 51‐year‐old male has suffered the gradual onset of difficulty with memory, concentration and cognition at age 50 and progressively developed severe dementia accompanied by muscle wasting and fasciculation prominent in the upper arms and shoulders and the bulbar muscles.
Abstract: A 51-year-old male has suffered the gradual onset of difficulty with memory, concentration and cognition at age 50. He has progressively developed severe dementia accompanied by muscle wasting and fasciculation prominent in the upper arms and shoulders and the bulbar muscles. EMG and muscle biopsy revealed denervation patterns and a CT-scan showed moderate cerebral atrophy. Cases of presenile dementia with motor neuron disease reported in Japan have been reviewed and the possibility of a new clinico-pathologic entity is discussed.


Journal ArticleDOI
TL;DR: Figure Pol vgraphlic (top) atid oscil/loscopic (/ottotI) recoridings of.s.s ssitll te7 reappearance of miuscle totie.
Abstract: Figure Pol vgraphlic (top) atid oscil/loscopic (/ottotI) recoridings of. (A) .seiLl-ie di.,ring rest. ninvoc/loic jerk.s. Tue oscil/oscopic recording s/iows. the siiu/ltaneoius occurrenCe of.spike (117d1 inYloC/iic Ierk.s. (B) sci--ire drlitig posture wit/il out-stretch/ec/ artiiu drllop of the lieaid ailcl iii.s. Tlhe oscilloscopic recordiig s110.S1 tIle coinicidenice of /ofs o tolle withi the .slow comiponenlt o/ t/he spike-and-wave comiip/ex; the spike is sync/hronou.s ssitll te7 reappearance of miuscle totie.

Book ChapterDOI
01 Jan 1981
TL;DR: Man is capable of performing a nearly infinite variety of movements, each of them generated by a specific pattern of motor neuron discharge, but only the simplest can be generated by the isolated spinal cord.
Abstract: Man is capable of performing a nearly infinite variety of movements, each of them generated by a specific pattern of motor neuron discharge. Only the simplest (e.g., withdrawal of a limb or scratching) can be generated by the isolated spinal cord. The motor repertoire of the spinal motor neurons and associated interneurons is limited to reflex responses (see Chap. 5). All other movements, ranging in complexity from coordinated walking to playing a Beethoven sonata, are generated by the central motor areas of the brain. The descending spinal tracts provide pathways for the central motor control of patterns of spinal motor neuron discharge. The central motor control systems include the motor cortex, which controls both pyramidal and extrapyramidal systems; the basal ganglia; and the cerebellum. Although at present many of the functions of these motor systems are not understood, each is thought to contribute in a specific manner to the generation of movement. The motor cortex-pyramidal system is associated with the voluntary performance of fines-killed movements. Gross involuntary movements are generated by the motor cortex-extrapyramidal system.