Showing papers on "Motor neuron published in 1978"

5'-Nucleotidase of microglial cells in the facial nucleus during axonal reaction.

Abstract: Transaction of the facial nerve causes proliferation of microglial cells in the facial nucleus. The miroglial cells can be seen in perineuronal and perivascular positions. A high activity of 5′-nucleotidase is demonstrated cytochemically in the plasma membranes of these cells. The increase of enzymatic sites for the production of adenosine during axonal reaction might be of functional significance for the regenerating motor neuron.

Contribution of individual mechanoreceptor sensory neurons to defensive gill-withdrawal reflex in Aplysia

Abstract: 1. To evaluate the contribution which mechanoreceptor sensory neurons make to the defensive gill-withdrawal reflex we developed an isolated reflex preparation. We then reduced this isolated reflex to a microcircuit (consisting of a single sensory cell and single motor cell) so as to causally relate the contribution of individual cells to the expression and plastic properties of the behavior. 2. Mechanoreceptor neurons make significant contributions to the amplitude and duration of the complex PSP in the motor neurons. A single spike in a sensory neuron produces an EPSP in the motor neuron which accounts for 7-36% of the complex EPSP produced by weak tactile stimulation of the skin. 3. More than 50% of the synaptic input to the gill motor neurons appears to be monosynaptic. Perfusing the ganglion with solutions of high divalent cations reduced the motor neurons' complex PSP by only 40%. 4. The population response of the mechanoreceptors to a point stimulus can be simulated by repetitively firing a single sensory neuron. Firing a single sensory cell discharges the motor neuron and produces a gill contraction similar to that produced by a natural stimulus. 5. Mechanoreceptors make monosynaptic connections onto gill motor neurons which decrement with repeated stimulation paralleling the decrement of the complex PSP to punctate tactile stimulation of the skin. 6. The results indicate that the known neural elements may quantitatively account for most of the expression of the behavior and its short-term habituation.

Excitation of Leg motor neurons by giant interneurons in the cockroachPeriplaneta americana

Abstract: 1. Giant interneurons (GI's) of the cockroachPeriplaneta americana were stimulated intracellularly while levator and depressor motor axons of the metathoracic leg were recorded extracellularly. The intracellular stimulus was a train of pulses, each of which evoked one GI action potential. The resultant burst of GI action potentials resembled that elicited by natural stimulation. The GI was identified by Procion Yellow iontophoresis. The motor axons were identified by spike height analysis. 2. Six of the seven identifiable GI's on each side have been studied. Four of these evoked trains of action potentials in the ipsilateral motor axons (Figs. 4, 6, 7, 8 and 9). Two GI's excited contralateral motor axons (Fig. 5). 3. Each GI evoked a characteristic and reproduceable response. 4. Increasing the pulse frequency or train duration of the intracellular stimulus leads to an increase in the number of action potentials evoked. 5. The giant-to-motor response persists, and sometimes increases, following decapitation (Fig. 11). 6. The responses of the motor neurons to each GI, and known responses of each GI to different wind directions, permitted predictions of the response of the motor neurons to different wind directions. These predictions were born out in experiments using controlled wind puffs (Figs. 12 and 13). 7. The results are discussed in relation to the responses of each GI to wind puffs of different directions, and the leg movements which these puffs elicit.

Diaphragmatic paralysis in motor neuron disease Report of two cases and a review of the literature

Abstract: Two patients presenting with respiratory insufficiency had diaphragmatic paralysis secondary to adult-onset motor neuron disease (progressive spinal muscular atrophy). A review of the literature discloses seven similar cases, most of them reported in non-neurological journals.

Werdnig-Hoffmann disease: proposal of a pathogenetic mechanism.

Abstract: Light and electron microscopic study and morphometric analysis were performed on the spinal cords and roots from six cases of acute Werdnig-Hoffmann disease and four control cases, in search of the pathogenesis of the selective motor neuron changes considered primarily responsible for Werdnig-Hoffmann disease This investigation posits a centrifugal traction mechanism based upon the discovery of cylindrical outgrowths of glial bundles, selective loss of large myelinated fibers, and axonal degeneration in the proximal portion of anterior spinal roots (and to a lesser extent in posterior spinal roots) in all six disease cases This traction mechanism exerts principally upon anterior spinal nerve roots and can account for morphologic and morphometric data characteristically ascribed to Werdnig-Hoffmann disease

Neuromuscular transmission in longitudinal muscle of the leech,Hirudo medicinalis

Abstract: A study was made of the pattern of motor innervation and neuromuscular transmission in the longitudinal muscle of the body wall of the leech. 1. The chemical sensitivity of muscle fibres was tested by applying acetylcholine (ACh) iontophoretically or in the form of droplets. The depolarizing action of ACh on the muscle fibres was greatest at sites where focal synaptic potentials are recorded after stimulation of the excitatory motor neuron. In many muscle fibres several sites of high ACh sensitivity may occur, a result which suggests that the muscle fibres are multiply innervated. Histologically identified nerve terminals were consistently observed at regions of high ACh sensitivity (Figs. 6, 7). 2. The cholinergic blocking agent curare reversibly reduced the amplitude of the excitatory synaptic potentials evoked by the motor neuron (Figs. 4, 5). 3. It is suggested that ACh is the transmitter released by the longitudinal motor neuron.

Specificity of afferent and efferent regeneration in the cockroach: establishment of a reflex pathway between contralaterally homologous target cells.

Abstract: 1. In 132 cockroaches the main leg nerve on one side (right), of the metathoracic segment was crossed to the opposite (left) side and allowed to regenerate. In 3-8 wk, 59% of the animals displayed reflex activity in the left leg (behaviorally demonstrated by leg withdrawal following tarsal stimulation). 2. EMGs from the femoral extensor revealed potentials characteristic of normal activity in the extensor, which is innervated by an identified motor neuron, Ds. 3. Intracellular recordings from processes within the right hemiganglion of the metathoracic ganglion (CNS) demonstrated 1:1 activity between a unit in the CNS recording and the EMG of the left extensor. Subsequent intracellular staining revealed that the unit was on the right side of the CNS and was identified as motor neuron Ds by the location of its soma and dendrites. This finding indicated that specific, contralateral, efferent reinnervation occurs in the cockroach. 4. In normal cockroaches a monosynaptic reflex exists between hair plate afferents and Ds. A temporal analysis (stimulus-interval histogram) indicated that the reflex is also established in the crossed-regenerated animals. These data suggested that specific contralateral afferent reinnervation also occurs in the cockroach and that the monosynaptic nature of the normal reflex was reestablished. 5. Therefore, cell-to-cell specificity in neuron-to-neuron or neuron-to-muscle interactions not only occurs in normally developing or regenerating animals but also occurs between contralaterally homologous target cells, given the proper experimental conditions. It is also suggested that this experimental procedure of redesigning pathways may be a useful tool for further studies of behavior.

Protein composition of cockroach muscles: identification of candidate recognition macromolecules.

Abstract: The protein composition of each of the coxal depressor muscles from the leg of the cockroach, Periplaneta americana, was analyzed by SDS polyacrylamide gel electrophoresis. The proteins from each muscle were fractionated according to their extractability in Ringer's solution, 1% Triton X-100 and 1% SDS. The gel protein patterns of the fractionated muscles revealed some biochemical differences that could be correlated with mechanical and ultrastructural differences observed among the muscles. In addition, proteins were detected that were considered to be candidate recognition macromolecules that are responsible for the intercellular recognition process that enables regenerating motor neurons to specifically recognize and make stable, functional connections only with the muscles to which they were originally connected. The major evidence for this identification of candidate recognition macromolecules was that their presence in the muscle could best be correlated with innervation by an identified motor neuron. In addition, these proteins remain present in denervated muscles for at least as long as it takes for the original innervation pattern to be reformed by the regenerating motor neurons.

Histochemical study of the muscle spindles in parkinsonism, motor neuron disease and myasthenia. An examination of the pathological fusimotor endings by the acetylcholinesterase technic.

Abstract: Pathological changes of the fusimotor endings in parkinsonism, motor neuron disease and myasthenia were examined by the acetylcholinesterase technic on serial sections. In parkinsonism, the diffuse endings, which are thought to be supplied by the static gamma nerve fibers, showed remarkable enlargement, while en plaque and en grappe endings were atrophic. In motor neuron disease, en plaque and en grappe endings, which are thought to be innervated by the beta nerve fibers and dynamic gamma nerve fibers respectively, revealed marked atrophy. However the diffuse endings were normal. In myasthenia gravis and myasthenic syndrome (Eaton-Lambert syndrome), en plaque and en grappe endings were atrophic, though only the diffuse endings were spared. The significance of these changes in the fusimotor endings is discussed.

Transformation of the afferent tactile signal into a motor command in the cat motor cortex

Abstract: Activity of 112 neurons of the precruciate motor cortex in cats was studied during a forelimb placing reaction to tactile stimulation of its distal parts. The latent period of response of the limb to tactile stimulation was: for flexors of the elbow (biceps brachii) 30–40 msec, for the earliest reponses of cortical motor neurons about 20 msec. The biceps response was observed 5–10 msec after the end of stimulation of the cortex with a series of pulses lasting 25 msec. Two types of excitatory responses of the neurons were identified: responses of sensory type observed to each tactile stimulation of the limb and independent of the presence or absence of motion, and responses of motor type, which developed parallel with the motor response of the limb and were not observed in the absence of motion. The minimal latent period of the responses of motor type was equal to the latent period of the sensory responses to tactile stimulation (20±10 msec). Stimulation of the cortex through the recording microelectrode at the site of derivation of unit activity, which increased during active flexion of the forelimb at the elbow (11 stimuli at intervals of 2.5 msec, current not exceeding 25 µA), in 70% of cases evoked an electrical response in the flexor muscle of the elbow.

Motor neuron diseases in man and animals.

Abstract: Aspects of motor neuron diseases in man are described and compared with a series of animal models for these disorders Such models provide new approaches to understanding many features of abnormalities of the central and peripheral nervous system