Showing papers on "Nervous system published in 1976"

From neuron to brain

Abstract: Introduction to the Fifth Edition PART I: INTRODUCTION TO THE NERVOUS SYSTEM Principles of Signaling and Organization Signaling in the Visual System Functional Architecture of the Visual Cortex PART II: ELECTRICAL PROPERTIES OF NEURONS AND GLIA Ion Channels and Signaling Structural Basis of Ion Channel Function The Ionic Basis of the Resting Potential The Ionic Basis of the Action Potential Electrical Signaling in Neurons Transport across Cell Membranes Properties and Functions of Neuroglian Cells PART III: INTERCELLULAR COMMUNICATION Mechanisms of Direct Synaptic Transmission Indirect Mechanisms of Synaptic Transmission Release of Neurotransmitters Neurotransmitters in the Central Nervous System Transmitter Synthesis, Transport, Storage, and Inactivation Synaptic Plasticity PART IV: INTEGRATIVE MECHANISMS Autonomic Nervous System Cellular Mechanisms of Behavior in Ants, Bees, and Leeches PART V: SENSATION AND MOVEMENT Sensory Transduction Transduction and Transmission in the Retina Touch, Pain, and Texture Sensation Auditory and Vestibular Sensation Constructing Perception Circuits Controlling Reflexes, Respiration, and Coordinated Movements PART VI: DEVELOPMENT AND REGENERATION OF THE NERVOUS SYSTEM Development of the Nervous System Critical Periods in Sensory Systems Regeneration of Synaptic Connections after Injury PART VII: CONCLUSION Open Questions Clinical relevance emphasized Appendices Current Flow in Electrical Circuits Metabolic Pathways for the Synthesis and Inactivation of Low Molecular Weight Transmitters Structures and Pathways of the Brain

The structure of the ventral nerve cord of Caenorhabditis elegans

Abstract: The nervous system of Caenorhabditis elegans is arranged as a series of fibre bundles which run along internal hypodermal ridges. Most of the sensory integration takes place in a ring of nerve fibres which is wrapped round the pharynx in the head. The body muscles in the head are innervated by motor neurones in this nerve ring while those in the lower part of the body are innervated by a set of motor neurones in a longitudinal fibre bundle which joins the nerve ring, the ventral cord. These motor neurones can be put into five classes on the basis of their morphology and synaptic input. At any one point along the cord only one member from each class has neuromuscular junctions. Members of a given class are arranged in a regular linear sequence in the cord and have non-overlapping fields of motor synaptic activity, the transition between fields of adjacent neurones being sharp and well defined. Members of a given class form gap junctions with neighbouring members of the same class but never to motor neurones of another class. Three of the motor neurone classes receive their synaptic input from a set of interneurones coming from the nerve ring. These interneurones can in turn be grouped into four classes and each of the three motor neurone classes receives its synaptic input from a unique combination of interneurone classes. The possible developmental and functional significance of these observations is discussed.

From neuron to brain: A cellular approach to the function of the nervous system

Abstract: The title of this book well describes its approach and its content. In a series of six sections the authors present a vivid and well-balanced discussion of the basic neurophysiologic mechanisms necessary for the transmission and integration of information, and then relate these mechanisms to such complex phenomena as visual perception, neural specificity, and the development of neuronal connections. The approach is highly personal and imaginative. It is also somewhat unorothdox. Instead of the usual progression from simple to complex, the authors begin, after a brief introduction, with a complicated topic-visual perception. Their discussion reveals the need to understand more basic issues. Hence they turn to the cellular aspects of neurophysiology , including the resting membrane potential, the action potential, and synaptic mechanisms. Next reflexes are considered, and then sensory receptors. Finally, the authors return to their starting point. Again they address themselves to visual perception; but this time, with the intervening material as a background, they are able to take the subject in new directions and to add additional perspectives. This individualistic approach works. The topics meld logically and coherently and the result is a beautiful perspective of many aspects of modem neurobiology . Emphasis is placed on basic neurophysiologic principles throughout the book. To do this, information obtained from many model systems is described in considerable detail. Some, such as the squid giant axon and the frog neuromuscufar junction, are familiar to the clinical neurologist accustomed to standard texts. Others, such as the crustacean stretch receptor, the goldfish Mauthner cell, and the leech CNS, are less conventional. They are systems, however, which have been used by modem neurophysiologists, including the authors and many of their present and former colleagues, to understand the cellular machinery of the nerve cell. And a great many of the principles which hold for invertebrates can be directly extrapolated to the mammalian central nervous system. Although the authors have achieved a masterful overview of neurophysiologic processes, they have not attempted a comprehensive treatment of the mammalian nervous system. The clinical neurologist will not find information concerning cerebellar function, the motor cortex, or the dorsal column. But the authors have succeeded in producing a text which, in the absence of previous neurophysiologic knowledge, can be read with comprehension and enjoyment. The reader is aided in this regard by a glossary, notes on nomenclature, an appendix on current flow, reviews of key terms, and informative schematic drawings. Furthermore, this volume provides a strong basis for reading and digesting other texts which deal more directly with clinically relevant material. Graduate students, residents, and large numbers of clinicians who have not received specific training in basic neurophysiology will find this volume an excellent guide to much of what is pertinent and modem in neurobiology. However, this is not a text just for the novice. A trained neurophysiologist may already know much of what is contained in these pages, but what a pleasure it is to read material that has seldom been presented so clearly! From Neuron to Bruin is heartily recommended.

fine structure of the nervous system

Abstract: Novel adhesive-sealant compositions useful for bonding metal and/or glass surfaces are disclosed. These adhesive-sealant compositions are comprised of an aluminous cement and the reaction product of a tetracarboxylic dianhydride or a tricarboxylic monoanhydride and a dihydrazine, dihydrazide or aromatic diamine. The adhesive sealant is capable of withstanding surface temperatures of up to 1,000 DEG F. without loss of adhesive or sealing properties.

Nonadrenergic inhibitory nervous system in human airways.

Abstract: Human airways, from the middle of the trachea to the distal bronchi, were studied in vitro for the presence of inhibitory nerves. The tissue was obtained from operations and from recent autopsies. ...

Electrotonic processing of information by brain cells

Abstract: In contrast to well-studied through-protection neurons that propagate information from one region to another in the central nervous system, short-axon or axonless neurons form local circuits, transmitting signals through synapses and electrical junctions between their dendrites. Interaction in this dendritic network proceeds without spike action potentials. Interaction is mediated by graded electrotonic changes of potential and is transmitted through high sensitivity (submillivolt threshold) synapses rather than by lower sensitivity (20 to 100-mv threshold) synapses typical of projection neurons. A crucial feature of local circuits is their high degree of interaction both through specialized junctional structures and through the extracellular fields generated by local and more distant brain regions. The anatomical evidence for the nature and distribution of neuronal local circuits in the nervous system is surveyed. Bioelectric mechanisms are discussed in relation to the special properties of local circuits, including dendrodendritic synapses, synaptic sensitivity, electrotonic coupling, and field effects. Intraneuronal and interneuronal transport of various types of substances suggests that the biochemical and the bioelectrical parameters are functionally interwoven. Through such interactions neuronal local circuits, with their distinctive properties, may play an essential role in higher brain function.

Pioneer neurones in an insect embryo.

Abstract: INSECT sense organs are produced by small groups of specialised epidermal cells1. The receptor neurones differentiate at the surface, so developing sensory axons grow inwards from the epidermis to the central nervous system (CNS). How do they find their way? During larval life the axons of newly differentiated sense cells combine with those of neighbouring receptors and thus are guided to the nearest branch of a peripheral nerve which carries them to the CNS2. At metamorphosis the axons of adult sensory neurones reach their central destination by growing along persistent larval nerves which are associated with the developing imaginal disks3–5. Thus with pathways to the ganglia already established, growth along existing nerves ensures the delivery of each generation of sensory axons to within a few hundred micrometres of their central targets. Just how the connection between the surface and the CNS is first established, whether by an outgrowth of nerves from the centre or by pioneering axons which grow inwards from the surface has never been shown, although some descriptions of embryonic development imply that the first axons to enter the developing appendages are growing outwards from the CNS6,7. Presumably these early centrifugal axons would provide a route for the later differentiating sensory fibres to follow in growth to the centre. Here, however, I report observations on the embryonic nervous system of Locusta migratoria which show that the first pathways between the epidermis and the central ganglia are formed by axons which grow inwards from peripheral neurones which differentiate early in embryonic life.

The shapes of sensory and motor neurones and the distribution of their synapses in ganglia of the leech: a study using intracellular injection of horseradish peroxidase.

Abstract: Three types of sensory neurones and two kinds of motor neurones in the segmental ganglion of the leech were examined with the light and electron microscope after intracellular injection of horseradish peroxidase (HRP) for a histological marker. The aim was to develop a method for identifying the synapses of specific cells in the ganglion’s complex neuropil and to form a picture of their distribution and structure. Reaction of HRP with different benzidine derivatives produces opaque and electron dense deposits. For light microscopy a blue stain is formed that makes processes visible in whole mounts millimeters away from the injection site at the soma. The reaction product for electron microscopy is distributed throughout the cytoplasm, yet ultrastructural details are preserved. The sensory neurones that respond specifically to touch or pressure or noxious mechanical stimuli to the skin share in their branching pattern a number of common features. A single process arising from each cell body forms large primary branches that pass through the neuropil and leave the ganglion by the ipsilateral connectives and roots. Within the neuropil these branches give rise to numerous smaller secondary processes. In contrast, the annulus erector and large longitudinal motoneurones send their main process across the ganglion to bifurcate and enter the contralateral roots. Secondary processes of the motoneurones are highly branched and more numerous than those of the sensory cells. Each type of sensory and motor cell is distinguished by the shape, length and distribution of its secondary processes. Secondary processes of sensory neurones exhibit numerous swellings and irregularly shaped fingers. Electron micrographs show that the sensory neurones make synapses at these specializations, each of which contacts several postsynaptic processes. The sensory neurones receive inputs at the same fingers and swellings, an arrangement suggesting that regions within a cell’s arborization may function semi-autonomously. The main process and large branches of the two motor neurones are studded with spines a few micrometres long and a fraction of a micrometre in diameter. Vesicle-containing varicosities from other cells make synaptic contact primarily with the spines, which themselves have few vesicles. These two motor neurones are largely, if not entirely, postsynaptic to other neurones within the leech nervous system.

The nerve growth factor: its role in growth, differentiation and function of the sympathetic adrenergic neuron.

Abstract: Publisher Summary This chapter discusses the role of nerve growth factor (NGF) in the growth, differentiation, and function of the sympathetic adrenergic neuron In the course of the divergence of cell lineages among the 10-12 billions of nerve cells that build the vertebrate nervous system, the sympathetic nerve cell is the first to acquire structural and biochemical differentiative marks In the 3-day chick embryo or in the 6-week, 1-cm-long human embryo, two thin bands of undifferentiated cells migrate from their site of origin, the neural crest, and move along the sides of the diminutive, still open, neural tube into the underlying mesenchymal tissue A few of these cells assemble as two strands and segregate from other neural crest derivatives, which give origin to sensory neurons, neural supporting elements, pigment, cartilage, and connective tissue The two cellular strands consist of loosely packed cells with no differentiating marks designated as the primary sympathetic trunks They segregate, in turn, into two components: one of these moves in a dorsolateral direction and gives rise to the segmentally arranged paravertebral ganglia, which settle in close apposition to the motor roots of spinal nerves; and the other migrates in a ventromedial direction in the pre-aortal region and forms the prevertebral sympathetic ganglia, which extend from the thoracic to the pelvic region

Vascular and brain dopamine beta-hydroxylase activity in young spontaneously hypertensive rats

Abstract: Dopamine beta-hydroxylase activity was higher in mesenteric vessels, adrenal glands, and serum of 3-week-old spontaneously hypertensive rats but lower in the locus coeruleus than it was in the control Wistar-Kyoto rats. The results support the concept that the nervous system is an important regulator of blood pressure.

Reactive Synaptogenesis in the Adult Nervous System

Abstract: In 1885 Exner suggested that the recovery of muscular contraction observed after partial transection of a motor nerve, but prior to regeneration of the damaged fibers, resulted from collateral growth of intact fibers and reinnervation of the muscle. Subsequently Edds (1950), Hoffman (1950), and others (Weddell et al., 1946; Hones et al., 1945; Weiss and Edds, 1946) demonstrated conclusively that the transection of few motor fibers could in fact result in axon collateral sprouting by the remaining undamaged fibers. This phenomenon was extended to connections between neurons when Murray and Thompson (1957) provided direct anatomical evidence for axon collateral sprouting in the partially denervated sympathetic ganglion and Liu and Chambers (1958) reported evidence for axon sprouting in the spinal cord. Over the last 20 years there has been an explosive growth of research on axon sprouting in the central nervous system. It is now clear that the phenomenon exists and can be highly selective in terms of which fibers sprout, which neurons are reinnervated, and at what ages it can be demonstrated.

Effects of methionine-enkephalin and leucine-enkephalin compared with those of morphine on brainstem neurones in cat

Abstract: Two new peptides, methionine-enkephalin (met-enkephalin) and leucine–enkephalin (leu-enkephalin), have been isolated from brain, identified and synthesised1. The interest in these compounds lies in their morphine-like activity which was recognised and tested by their action on isolated preparations from the peripheral nervous system. Since morphine is used for its central action in producing analgesia, it is important to investigate whether these substances have activity in the central nervous system similar to that of morphine. We report here the findings of similar depressant actions of all three substances on brainstem neurones in the cat.

Neural principles in vision

Abstract: Opening Remarks.- 1 Vertebrates.- 1.1 Patterns of Golgi-Impregnated Neurons in a Predator-Type Fish Retina.- 1.2 A Comparative Study of the Horizontal Cells in the Vertebrate Retina: I. Mammals and Birds.- 1.3 Neuronal Connections and Cellular Arrangement in the Fish Retina.- 1.4 Golgi, Procion, Kernels and Current Injection.- 1.5 Electrophysiological and Histological Studies of the Carp Retina.- 1.6 Interactions and Feedbacks in the Turtle Retina.- 1.7 Interactions between Cones and Second-Order Neurons in the Turtle Retina.- 1.8 Synaptic Transmission from Photoreceptors to the Second-Order Neurons in the Carp Retina.- 1.9 Retinal Physiology in the Perfused Eye of the Cat.- 2 Arthropods.- 2.1 Adaptations of the Dragonfly Retina for Contrast Detection and the Elucidation of Neural Principles in the Peripheral Visual System.- 2.2 Voltage Noise in Insect Visual Cells.- 2.3 Spectral and Polarization Sensitivity of Identified Retinal Cells of the Fly.- 2.4 Neuronal Processing in the First Optic Neuropile of the Compound Eye of the Fly.- 2.5 Beyond the Wiring Diagram of the Lamina Ganglionaris of the Fly.- 2.6 Mosaic Organizations, Layers, and Visual Pathways in the Insect Brain.- 2.7 Structure and Function of the Peripheral Pathway in Hymenopterans.- 2.8 Neuronal Architecture and Function in the Ocellar System of the Locust.- 2.9 The Resolution of Lens and Compound Eyes.- 3 Molluscs.- 3.1 Ultrastructural Observations on the Cortex of the Optic Lobe of the Brain of Octopus and Eledone.- 3.2 The Question of Lateral Interactions in the Retina of Cephalopods.- 3.3 Hyperpolarizing Photoreceptors in Invertebrates.- 3.4 The Economy of Photoreceptor Function in a Primitive Nervous System.

Gonadotropin-releasing hormone and thyrotropin-releasing hormone: distribution and effects in the central nervous system.

Abstract: Publisher Summary This chapter discusses the distribution and effects of gonadotropin-releasing hormone (GnRH) and thyrotropin-releasing hormone (TRH) in the central nervous system (CNS). The studies presented in the chapter provide evidence for the ubiquitous distribution of GnRH and TRH in extrahypothalamic regions of the rat nervous system, including the pineal gland, anterior pituitary, midbrain, cerebral and cerebellar cortices, and brain stem. TRH has also been demonstrated by radioimmunoassay in the rat spinal cord and in human cerebral spinal fluid. The heterogeneous distribution pattern of these peptides, found in greatest concentrations in hypothalamus and midbrain, corresponds with regions endowed with biogenic amines, inducing dopamine and norepinephrine. Hypothalamic peptides, such as melanocyte-inhibiting factor (MIF)-1, ProLeuGlyAmide, TRH, GnRH, and growth hormone-inhibiting hormone (GHIH), exert behavioral influences in animal bioassay models that do not depend on the integrity of the endocrine system. These have been exemplified by L-dopa potentiation in MIF-1, TRH, GnRH, and GHIH, serotonin potentiation in TRH and GnRH, reversal of barbiturate hypnosis in TRH, and protection against audiogenic seizures in GnRH. The direct application of three of these peptides, TRH, GnRH, and GHIH, on individual neurons at many levels of the rat CNS results in rapid and reversible suppression of action potentials, similar to the inhibitory effects of histamine and dopamine on identical neurons. Electrical stimulation of 134 tuberoinfundibular neuron axon terminals reveals efferent projections to unexpected areas of the CNS, including the anterior hypothalamic area, medial preoptic area, and the nucleus dorsalis medialis of the thalamus. These latter observations raise the possibility that these peptidergic neurons can be a potential source for hypothalamic peptides identified in the outer regions of median eminence.

Dopaminergic Agents: Influence on Serotonin in the Molluscan Nervous System

Abstract: Treatment of the mussel Mytilus edulis with 6-hydroxydopamine or with alpha-methyl-p-tyrosine decreased dopamine and increased serotonin in the nervous system. Treatment with dopamine decreased serotonin concentrations and prevented the effect of 6-hydroxydopamine. The serotonin concentration appears to be determined in part by the concentration of dopamine.

Maturation of the Mammalian Nervous System and the Ontogeny of Behavior1

Abstract: Publisher Summary This chapter describes the origins of the central nervous system, cerebellum: intrinsic connections and inherent growth mechanisms underlying locomotor behavior, cerebral cortex: extrinsic connections and CNS organization, and limbic system structures including illustrations of neuronal plasticity in development. The chapter also discusses the studies on several areas of the cerebral cortex to elucidate the behavioral significance of pathways connecting distant structures, the organization of structures into systems, and the modulation of development by experience. The development of the nervous system is strongly influenced by the external environment and the opportunities that it provides for experience and learning. Cells destined to become neurons are generated at specific days in specific places on the embryonic neural plate. These cells migrate, again according to precise timetables, to their ultimate destinations. Development is a sequential process, and one function of a stepwise maturational progression may be to regulate the order and impact of internal and external stimuli and experience on the developmental process itself. Thus, uniformity and orderliness in the sequence of exposure to the environment may be governed and programmed by the developmental timetables of different parts of the nervous system. The rules and mechanisms for regenerative phenomena in the developing nervous system are not yet well understood, but it is most unlikely that when discovered, they will overturn basic concepts of the CNS structure and function.

Excitability of nerve-free hydra

Abstract: THE simplest nervous systems known are those of Coelenterate polyps, of which hydra is one. Nerve cells of the common freshwater hydra occur in a diffuse, two-dimensional nerve net dispersed among the epithelial cells of the outer, ectodermal layer1–4. There are also a few nerve cells in the inner, endodermal layer but these are scattered and do not seem to form a continuous net5. Nowhere in a hydra are there nerve cell concentrations or clusters of sufficient complexity to warrant being called ganglia. There have been many behavioural and electrophysiological investigations of hydra6–9, but the function of the nervous system in the control of behaviour is still unclear. In other coelenterates epithelial cells have been shown to be capable of propagating behavioural signals10,11. Several conducting systems coupled with spontaneously active pacemakers have been identified in hydra, but it is not known which of these conducting systems, if any, are neuronal and which result from activity in non-neuronal, epithelial cells. We have investigated the behaviour of Hydra attenuata in effectively nerve-free animals and show that such behaviour as remains, is controlled by non-neuronal cells.

Role of the epiphysis in the migration of the retinal epithelial pigment in some teleosts

Abstract: Role of the pineal organ (epiphysis) in the migration of the retinal epithelial pigment in response to changes in ambient light conditions was investigated. Pinealectomy, and section of the optic nerves and the spinal cord enable us to conclude that the influence of the nervous system is minimal or lacking in this phenomenon, which seems to be controlled mainly by a humoral factor. Pigment migration within retinal cells is directly affected by intraocular injection of melatonin. The results suggest that a humoral factor of the pineal organ, possibly melatonin, may play a role in the physiological control of retinal pigment-granule movements.

On the occurrence of Schwann cells within the normal central nervous system.

Abstract: The presence of Schwann cells and P.N.S. myelin are reported in subpial areas of apparently normal spinal cord from one control rabbit, two experimental rabbits and one experimental guinea pig. These P.N.S. elements exerted no adverse effects upon local C.N.S. components. The occurrence of ectopic Schwann cells in the normal C.N.S. has also been reported elsewhere in studies on normal human spinal cord tissue. The propensity for Schwann cells to reside in the normal C.N.S. of several species makes it necessary for experiments and hypotheses on the aetiology of Schwann cell invasion into the abnormal C.N.S. to take the present phenomenon into consideration.

Distribution of monoaminergic neurons in the nervous system of non-malacostracan crustaceans.

Abstract: A comparative investigation of the distribution of monoaminergic neurons in non-malacostracan crustaceans was performed with the histochemical fluorescence method of Falck-Hillarp.Two fluorophores were found: the more widespread of the two emits a green fluorescence; and the more sparsely distributed emits a yellow to brown-yellow fluorescence.Specific green fluorescent areas were shown to exist in the protocerebrum. The central body and the optic ganglia of the compound eye (where present) are always fluorescent. Moreover, the centre of the nauplius eye may have a green fluorophore, as in ostracods, and a neuropile area, here called the frontal area. These neuropile centres are known from ordinary histological studies of the nervous system. In addition, there are specific monoaminergic centres, such as the so-called dorsal area of phyllopods and anostracans as well as the copepod specific areas. Specific monoaminergic areas appear in the deutocerebrum and the suboesophageal ganglion where they are particularly well developed.Presumed sensory neurons in the cavity receptor organ of Artemia salina are shown to be monoaminergic. Monoaminergic sensory neurons have not been described previously in Arthropods.Presumed motor innervation of hind-gut and trunk muscles is also found, and it is concluded that in crustaceans neurons of every type (sensory, internuncial, motor) may be monoaminergic. (Less)