Showing papers on "Nervous system published in 1974"

Analysis of Vertebrate Structure

Abstract: INTRODUCTION. The Nature Of Vertebrates Morphology. SURVEY OF VERTEBRATE ANIMALS: THE PRINCIPAL STRUCTURAL PATTERNS. Nature, Origins, and Classification of Vertebrates. Fishes. Tetrapods. THE PHYLOGENY AND ONTOGENY OF STRUCTURE: EVOLUTION IN RELATION TO TIME AND MAJOR TAXA. Early Development. Integument and Its Derivatives. Teeth. Head Skeleton. Body Skeleton. Muscles and Electric Organs. Coelom and Mesenteries. Digestive System. Respiratory System and Gas Bladder. Circulatory System. Excretory System and Osmoregulation. Reproductive System and Urogenital Ducts. Nervous System: General, Spinal Cord, and Perpheral Nerves. Nervous System: Brain. Sense Organs. Endocrine Glands. STRUCTURAL ADAPTATION: EVOLUTION IN RELATION TO HABIT AND HABITAT. Structural Elements of the Body. Mechanics of Support and Movement. Form, Function, and Body Size. Running and Jumping. Digging, and Crawling without Appendages. Climbing. Swimming and Diving. Flying and Gliding. Energetics and Locomotion. Feeding. Appendix: Anatomical Preparations. Glossary. Index.

Tumours of the nervous system.

Abstract: Tumours of the nervous system of animals are not as rare as has been commonly believed. In dogs, especially the brachycephalic breeds, these tumours occur as frequently as in man. The tumours are grouped according to tissue of origin as follows: nerve cells, neuroepithelium, glia, peripheral nerves and nerve sheaths, meninges and vessels, the pineal and pituitary glands, and the craniopharyngeal duct. Tumours of the glia are relatively common and are divided into the following types: astrocytoma, oligodendroglioma, glioblastoma, spongioblastoma, medulloblastoma, and unclassified gliomas.

Neurotoxicity of Commonly Used Antineoplastic Agents

Abstract: THE incidence of neurologic disorders has been steadily increasing in several neoplastic diseases as recent advances in therapy have lengthened patient survival.1 2 3 The neurologic complications of cancer most frequently result from metastasis to the nervous system or compression of neural structures by extraneural tumor. In addition, an interesting group of nonmetastatic neuromuscular disorders has recently been described,4 , 5 and the broad concept of "carcinomatous neuromyopathy" is frequently invoked to explain obscure neurologic symptoms in patients with cancer.6 However, it is also important to realize that neurologic dysfunction may be iatrogenic — i.e., caused by the treatment of cancer. Radiation myelitis and . . .

Synaptic interactions of identified nerve cells in the spinal cord of the sea lamprey.

Abstract: As part of a continuing study on the organization of the lamprey nervous system, two additional groups of interneurons have been identified by physiological and morphological criteria in the isolated spinal cord of Petromyzon marinus. These and other identified nerve cells were tested for synaptic interactions using separate intracellular microelectrodes for stimulation and recording. 1 Edge cells were identified by their unusual location in the lateral fiber tracts of the spinal cord. Their axons extended rostrally either on the ipsilateral or contralateral side of the cord. 2 Some edge cells showed polysynaptic EPSP's and IPSP's after stimulation of sensory dorsal cells, but interactions with other identified neurons were rare. A single cell was excited by a giant interneuron. One edge cell produced IPSP's in a contralateral edge cell, and another produced IPSP's in lateral cells on the opposite side of the spinal cord. Thus, some edge cells have an inhibitory function. 3 Lateral cells were distinguished from giant interneurons and edge cells by their cell bodies in the lateral grey of the spinal cord in the gill and trunk regions, their ipsilateral dendrites, and their long ipsilateral axons extending as far as the tail. 4 Lateral cells were excited and inhibited polysynaptically by sensory dorsal cells and, in turn, produced weak IPSP's in unidentified neurons. Stimulation of lateral cells produced neither visible movements peripherally nor synaptic potentials in other lateral cells, in giant interneurons, or in edge cells. 5 Giant interneurons were previously identified on the basis of their cell bodies in the caudal half of the spinal cord, their bilateral dendrites, and their long contralateral axons extending towards the brain. Giant interneurons exhibited unitary composite EPSP's when more caudal giant interneurons were stimulated. The two components of the EPSP were due to electrical and chemical transmission. Under the electron microscope a contact between a dendrite of one giant interneuron and the probable axon of another had separate junctions resembling chemical and electrical synapses. 6 Intracellular stimulation of sensory dorsal cells produced both monosynaptic and polysynaptic EPSP's in giant interneurons. Some dorsal cells produced unitary composite EPSP's Giant interneurons are part of a convergent, multispecific sensory system extending towards the brain.

Pattern of remyelination in the CNS

Abstract: IT has been suggested that reduction of internodal length may be a feature of remyelinated central nerve fibres as it is of peripheral nerve fibres1. As the technique for measuring internodal length of nerve fibres in the central nervous system (CNS) is tedious and requires a high degree of skill and patience from the investigator2, it is unlikely that this method can be applied to routine neuropathological investigations. Recent ultrastructural studies on remyelination in the mouse, following primary demyelination induced by feeding cuprizone (Bis - cyclohexanone - oxaldihyrozone)3–5 have shown that measurements of the relationship between myelin sheath thickness and axon diameter provides an easier method of identifying remyelinated axons.

Myosin from cross-reinnervated cat muscles.

Abstract: Correlated physiological changes, and structural and functional changes in myosin, following cross-reinnervation of cat fast-twitch and slow-twitch muscles, indicate that the myosin phenotype is controlled through the nervous system.

Inductive functions of the nervous system.

Abstract: In addition to their responsibility for the minute to minute control of behavior and homeostasis, nerve cells are important in maintaining the long term stability of structure and function of the nervous system and the cells it innervates. The trophic action of motor nerve cells on skeletal muscles is a well known example of such an activity. Miledi (270) defined trophic actions as due to "an influence of the nerve not mediated by impulses," but it has recently been suggested that only some of the classical trophic effects on skeletal muscle are exerted independently of nerve im­ pulses and/or muscle contraction. For example, direct electrical stimulation of a denervated muscle may reverse the development of denervation hypersensitivity (83, 241). The presence and the function of muscie innervation have a variety of in de pen­ dentiy exerted long term effects on the motoneurone itself, and on the physiological and anatomical state of the muscle. For example, botulinus toxin affects most of the trophic actions of the nerve except the maintenance of end plate cholinesterase (82), preganglionic cholinergic nerves form functional synapses on frog skeletal muscle but do not induce endpiate cholinesterase (223), and adrenergic nerves can prevent denervation fibrillation without forming functional synapses (265). Similarly com­ plex sets of interactions have been described elsewhere in the peripheral and auto­ nomic nervous systems, and within the brain as well.

Vital staining of specific monoamine-containing cells in the leech nervous system.

Abstract: Neutral red and several related dyes selectively stain certain cells in the ventral nerve cord of the leech. These cells are identical with those that can be shown by the FalckHillarp fluorescence technique to contain serotonin or a catecholamine; evidence suggests that the catecholamine is dopamine. Although the mechanism of staining remains unknown, it does not depend on active uptake of the dye. Stained cells in ganglia that were incubated for 12 hours in culture medium retained their normal physiological properties. Thus neutral red may be useful for locating specific monoamine-containing neurons in living nervous tissue.

Hormonal Mechanisms Underlying Insect Behaviour

Abstract: Publisher Summary The behavioral responses of an animal to its environment can be drastically modified by changes in its hormonal milieu. Hormonal effects on behavior have been long established in vertebrates, and have been studied primarily with respect to the effects of hormones on sexual behavior. This chapter is concerned with actions of the endocrine system on the nervous system, which lead to overt behavioral acts. Hormones are well suited for modulating the general responsiveness of the nervous system because they have access to all of the neurons. For a widespread change to be mediated through purely neural means, requires an extensive series of excitatory and inhibitory networks. The extra neural circuitry will provide rapid and “fine-tuned” modulation of response thresholds, but it will also increase the complexity and size of the CNS. Hormonal modulation, by contrast, apparently either facilitates or suppresses neural pathways, according to the response characteristics of the particular neurons involved. The manner by which hormones exert their effects on the nervous system is unknown. They may alter the permeability characteristics of the neurons, affect the level of transmitter synthesis, facilitate, or block synaptic transmission, etc. Invertebrates, with their simplified nervous systems and their large, identifiable neurons, have proved to be excellent animals in which to answer many questions concerning the functioning of the nervous system.

The morphology of cricket giant interneurons.

Abstract: Axonal iontophoresis of cobalt chloride was used to describe the morphology of the seven largest interneurons in the abdominal nervous system of the cricket Acheta domesticus. The somata of these neurons are all found in the terminal (5th) abdominal ganglion. This ganglion is derived from four primitive segmental ganglia (the 7th–10th primitive segments) and the morphology of the interneurons within this ganglion suggests that the neurons are derived from different primitive segments. Furthermore, some of the neurons appear to be serially homologous elements. Three aspects of the morphology support these suggestions: (1) soma position, (2) relative positions of commissural processes, and (3) the general shape and extent of dendritric fields.

The pathogenesis of pseudorabies in mice following peripheral inoculation.

Abstract: Summary Three-week-old mice were inoculated with pseudorabies virus by means of the left hind foot pad. Infectious virus was isolated from tissues in the sequence: foot pad, sciatic nerve and dorsal root ganglion, lower, middle, upper spinal cord, and brain. Virus was recovered in one instance only from the liver, but could not be recovered from the spleen or heart blood. The involvement of the kidneys, adrenal glands, coeliac ganglion and skin in the spread of infection was also studied. The possible role of the autonomic nervous system in the pathogenesis is suggested. In this respect, immunosympathectomy prior to inoculation reduced the incidence of infection in the adrenal glands and kidneys. Interruption of the sciatic and femoral nerves led to reduced mortality and an altered pathogenesis. A new pattern of virus isolation from the tissues was observed in mice dying at later times following section or ligation of these nerves. The electron microscope observations indicated that neurons rather than glia are of major importance in facilitating virus spread within and from the nervous system.

Distribution of acetylcholine, choline, choline acetyltransferase and acetylcholinesterase in regions and single identified axons of the lobster nervous system.

Abstract: — Acetylcholine, its precursor (choline), and the enzymes of its biosynthesis and degradation (choline acetyltransferase and acetylcholinesterase, respectively) have been studied and quantified in extracts of several regions of the nervous system of the lobster and in single, isolated axons of identified efferent excitatory, efferent inhibitory and afferent sensory neurons. The choline acetyltransferase is a soluble enzyme similar to that from other species. The predominant acetylcholine-hydrolysing enzyme is largely membrane-bound and has been characterized as a specific acetylcholinesterase. A single peak of acetylcholinesterase activity can be detected upon velocity sedimentation analysis of Triton X-100-treated extracts of all regions of the nervous system. Choline acetyltransferase distribution parallels that of sensory neural elements, and its specific activity shows nearly a 500-fold difference from the richest to the poorest neural source. Acetylcholinesterase levels span only a 23-fold range, and activity is found in all neural regions, including those free of known sensory components. A radiochemical microassay for choline and acetylcholine in the range of 20–2000 pmol is described in detail. All 3 types of axons contain comparable levels of choline (ca. 2 pmol/μg protein), but acetylcholine is asymmetrically distributed. Efferent axons contain no detectable acetylcholine, while sensory axons from abdominal muscle receptor organs have an average of 1·9 pmol/μg protein. Choline acetyltransferase is similarly distributed; sensory axons show at least 500-fold greater activity than efferent axons. Acetylcholinesterase is nearly uniformly distributed among the three types of fibres. These results are discussed in terms of a general view of transmitter accumulation in single neurons.

Branchial innervation and ciliary control in the ascidian Corella.

Abstract: The cilia lining the stigmata of the branchial sac of an ascidian circulate water through the animal. These stigmatal cilia are under nervous control; when either siphon is stimulated, both siphons close by muscular contractions and at the same time the stigmatal cilia stop beating simultaneously in all parts of the branchial sac. Spontaneous ciliary arrests may also occur, with or without associated closure of the siphons. Elements of the branchial nervous system that run in the gill bars are assumed to be concerned in coordination of the ciliary arrests. The majority of the branchial nerve fibres emerge dorsally from the visceral nerves that form the posterior brain roots, although nerves are also believed to enter the branchial sac along its anterior margin. No cell bodies could be found in the branchial nerves or in the visceral nerves, so that the cell bodies of the branchial nerve fibres are assumed to lie in the central nervous system. The branchial nerve fibres form a peripheral conducting net extending throughout the branchial sac. Branches of these nerve fibres terminate in contact with some of the ciliated cells; cell-to-cell conduction (through close junctions?) probably spreads excitation to the other ciliated cells. Nerve-nerve junctions appear to be more sensitive to curare than those between nerves and ciliated cells. Electrical recordings from the branchial sac, obtained with suction electrodes, show that arrest of the cilia is accompanied by electrical activity, and that prolonged arrest is maintained by trains of regular pulses. Intracellular microelectrodes in the ciliated cells indicate that these cells have a negative resting potential of 30-40 mV, and that a ciliary arrest is associated with a positive-going spike of 45-50 mV. The externally recorded 'ciliary arrest potentials' probably represent the coordinated depolarization of many ciliated cells. The rhythmical character of the trains of pulses presumably depends on pacemaker activity; this is not localized, since intact organisms or isolated small portions of the branchial sac are capable of generating similar trains of pulses. During the arrest response the stigmatal cilia first perform a reverse beat, then maintain the reverse position for several seconds before slowly relxaing and after several more seconds recommencing to beat with progressively increasing amplitude. The duration of the arrest response varies in media with different concentrations of the common cations, and also varies in response to repetitive stimulation, in a manner which suggests that the depolarization of the ciliated cells is associated with an influx of Ca$^{2+}$, so that the ciliary control here may have some close parallels with that described for Paramecium.

Anatomy of the Afferent Auditory Nervous System of Mammals

Abstract: The understanding of the auditory system depends, finally, upon the fitting together of anatomical, physiological and behavioral analyses of the system. Each analysis presents a picture of the system based upon its own experimental procedures. It is the purpose of this chapter to present the auditory system, from acoustic nerve to cerebral cortex, as it stands revealed by anatomical experiments and observations.

The distribution of muscarinic receptor sites in the nervous system of the dog

Abstract: — The concentration of muscarinic receptors has been measured in 22 areas of the dog nervous system by measuring the atropine-sensitive uptake of tritium-labelled propylbenzilylcholine mustard. The highest concentration of receptor was found in the caudate nucleus, intermediate concentrations were found in five areas of cerebral cortex, the other basal ganglia and the superior colliculus. Significant concentrations were found in the corpus callosum and subcortical white matter, and are believed to be on axons derived from cholinoceptive neurons. The results are discussed in relation to other evidence concerning cholinergic transmission in the nervous system.

Neuropathological and biochemical studies in Fabry's disease.

Abstract: Pathological and biochemical studies were performed on a patient with Fabry's disease. Abnormal deposits in the nervous system were restricted mainly to neurons of the autonomic nervous system. Affected neurons were found in the supraoptic and paraventricular nuclei, the midline nucleus, substriatal grey, nucleus amygdalae, presubiculum of hippocampus, fifth and sixth cortical layers of the parahippocampus and inferior temporal gyrus, dorsal motor nucleus of the vagus, superior and inferior salivatory nuclei, Edinger-Westphal nucleus, reticular formation of the pons and medulla oblongata, trigeminal ganglia, non-pigmented cells of the substantia nigra, intermediolateral column, spinal dorsal root ganglia, sympathetic ganglia and the submucous and myenteric plexuses. Abnormal deposits were found also in the periventricular glial cells, perineurium, the endothelial and smooth muscle cells of blood vessels throughout the body, the heart, kidneys and reticuloendothelial cells of many organs. The histogram of the sural nerve showed a decrease in the smaller myelinated and unmyelinated fibers. The abnormal deposits were glycolipids, CTH and CDH. Although there were two distinct staining characteristics of the deposited material with Luxol fast blue and PAS in paraffin section, these differently stained deposits could not be differentiated by histochemical and biochemical studies.

NS-1 (Nervous System Antigen-1), a Glial-Cell-Specific Antigenic Component of the Surface Membrane

Abstract: A methylcholanthrene-induced glioblastoma of the C57BL/6 inbred mouse strain was used to raise antibodies in C57BL/6 and C57BL/10 inbred mice and in (C57BL/6 × DBA/2) and (C57BL/6 × Balb/c) F1 hybrids. When examined by the cytotoxicity test, these antibodies define a cell-surface component (or components) found exclusively on brain tissue of all mouse strains studied and of several other mammalian species including man. The antigen, named NS-1 (nervous system antigen-1), is present on cells of three of the four mouse-glial-cell tumors tested, but not on the C1300 neuroblastoma, a tumor of neuronal origin. NS-1 occurs in higher concentration in regions of the nervous system richer in white than in gray matter, and in lower than normal concentrations in brains of myelindeficient neurological mutant mice. The concentration of NS-1 gradually increases postnatally and reaches the adult level between the third and fourth week. The existence of more than one allele or genetic locus controlling NS-1 activity is suggested by the occurrence of higher amounts of NS-1 in brains of the A and C57BL/6 than of the Balb/c and DBA/2 mouse strains. NS-1 is the first cellsurface component to be described that is not only unique to nervous tissue, but specific for glial cells.

Copper deficiency and the central nervous system. Myelination in the rat: morphological and biochemical studies.

Abstract: Less histologically demonstrable myelin was present in the central nervous system of newborn rats having a mean brain copper concentration only 20% that of normal Tremor, spontaneous tail elevation and a loss of aggressive character were consistent features Significant decreases in typical myelin lipids, sulfatide, and especially galactocerebroside were found in agreement with the histological deficit The composition of gangliosides and phospholipids were unaltered except for a slight enrichment in phosphatidylcholine Galactosylation of ceramide, in vitro, was depressed in copper-deficient brain and the relevance of this finding is discussed Swayback, a non-febrile, ataxic disorder of newborn and young lambs, was first reported by Bennetts in Western Australia (4, 5) The disease is associated with low levels of copper in tissue of both ewes and affected lambs (6) due to low copper content in pastures Supplementation with copper of either the ewe during pregnancy, or the lamb directly, prevents manifestations of the disease (7, 15) Although a well known entity in sheep, a condition resembling swayback also has been reported in copper-deficient goats (26, 37, 41) and pigs (33, 50) The common pathological features of swayback include symmetrical demyelination with subsequent cavitation of the cerebral white matter and degeneration of descending tracts in the spinal cord (28, 42, 43); however, myelin aplasia has also been observed (27) Similar changes have been induced in lambs (31) and guinea pigs (16) born to mothers fed experimental diets deficient in copper, but myelin changes have not been reported in the copper-deficient rat Demyelination and amyelination accompanying swayback disease in sheep are associated with a depletion of typical myelin lipids such as cerebroside (27) The decrease in lipids may be involved in the pathogenesis of the disease in the nervous system, but the basic defect that results in decreased myelin lipid is not known Recently, DiPaolo and Newberne (13) observed a variety of clinical and morphological abnormalities in copper-deficient newborn rats which include a high mortality, retarded growth, petechial and ecchymotic hemorrhages in brain, muscle and subcutaneous tissue, focal necrosis in the brain associated with neonatal incoordination of the hind limbs, hemorrhagic necrosis of the liver, cardiac hemorrhage, and severe, widespread vascular dilation in cardiac walls and septae We also observed behavioral changes in rats having a mean brain copper concentration about 20% of normal The purpose of this report is to describe further these changes, present the histological myelin anomalies observed in these animals, and correlate this morphological observation with quantitation of brain lipids and the in vitro synthesis of galactocerebroside

The pharmacology of the insect nervous system

Abstract: Publisher Summary This chapter focuses on axonal and synaptic pharmacology of the insect nervous system. It describes the mechanisms of nerve excitation and conduction and of synaptic transmission. The efficiency of drugs is a function of the ability to reach the receptor sites within the nervous tissue. The chapter further discusses the mechanism whereby ions and molecules are excluded from the nervous system. It has been shown that in insect species, the changes in the chemical composition of the medium bathing the nervous system are not reflected in equivalent changes in neuronal function. An earlier study of the rates of penetration of a number of compounds into the nervous system indicated that insect ganglia contain one or several barriers. This barrier(s) is able to discriminate against size, charge, and polarity of the molecule. It has been demonstrated that uncharged molecules penetrated easily into the central nervous system (CNS) than the charged ones. Investigations have shown that regulation could take place at different levels of the nervous system. Insects do not differ from other animal species and that the mechanisms for excitation, conduction. The synaptic transmission is not significantly different from those found in other invertebrate or vertebrate species.

Persistent modification of synaptic interactions between sensory and motor nerve cells following discrete lesions in the central nervous system of the leech

Abstract: We have examined changes that develop in the synaptic interactions of sensory and motor nerve cells following surgical lesions to the central nervous system of the leech. In one type of operation an individual ganglion was isolated from the rest of the nervous system by severing all the incoming and outgoing fibres. During the next few weeks, marked changes appeared in synaptic interactions.1. In chronically isolated ganglia inhibitory potentials were recorded in the motoneurone which raises the skin into ridges (the AE cell) following impulses in sensory neurones that respond to pressure (P) or noxious (N) stimuli. In contrast the same AE cell in ganglia taken from normal animals shows excitatory synaptic potentials when the P or N sensory cells are stimulated.2. Another altered synaptic interaction in ganglia isolated by lesions was that between sensory cells responding to touch and a motoneurone that supplies longitudinal muscles (L cell). Instead of the pure, electrical coupling potential seen normally, a large, additional chemically mediated excitatory potential was also apparent.3. Some of the changes in synaptic interactions were not restricted to synapses within the isolated ganglion, but appeared gradually over the following year in successive ganglia along the length of the ventral nerve cord.4. Indirect evidence suggests that the altered synaptic potentials that became conspicuous after operations are also present but smaller and obscured in normal animals.5. It is concluded that some synapses in the leech nervous system are more readily changed than others by cutting the connectives. Furthermore, these changes influence in a predictable manner the way in which the animal behaves in response to mechanical stimuli.

Neural integration (central nervous system)

Abstract: Publisher Summary Insects as multicellular and highly organized animals have developed two systems for the integration and coordination of cellular and organ functions: (1) the nervous system and (2) the endocrine system. Both consist of cellular units and communication between them and other body cells is an essential feature of insect life. The two systems are responsible for adjusting the animal to rapid and slow environmental changes. They are connected structurally and functionally by the responsiveness of neurons to humoral factors and in taking over the secretory function from cells belonging to the nervous system and initiating the release of hormones by nervous commands. Therefore, neurosecretory cells are believed to be a link between nervous and endocrine elements and were found to possess neuronal and endocrine properties in an earlier study. This chapter discusses some of the aspects of integrative activity taking place in insect nervous systems. It focuses on some of the functions of its central part in the control of behavioral activities.