Showing papers on "Nervous system published in 1971"

Atlas of the Mouse Brain and Spinal Cord

Abstract: Atlas Of The Mouse Brain The Allen Mouse Brain Atlas includes a full-color, high-resolution anatomic reference atlas accompanied by a systematic, hierarchically organized taxonomy of mouse brain structures. In 2011, the reference atlas was updated to enable interactive online exploration of the atlas and to provide a deeper level of 3-D annotation for informatics analysis and viewing in the Brain Explorer® 3-D viewer.

Dopamine-sensitive adenyl cyclase: possible role in synaptic transmission.

Abstract: An adenyl cyclase activated by low concentrations of dopamine has been found in the mammalian superior cervical sympathetic ganglion The existence of this enzyme may account for the increased amount of adenosine 3',5' monophosphate associated with synaptic activity in the ganglion The results suggest that the physiological effects of dopamine in the ganglion, and possibly elsewhere in the nervous system, may be mediated by stimulating the synthesis of adenosine 3',5'-monophosphate

The Fine Structure of the Nervous System

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Summing up: some implications of the neuron as a secreting cell.

Abstract: ‘Believing that the nervous system is something more than a mere system of conducting paths, I formed the hypothesis that nerve cells are true secreting cells, and act upon one another and upon the cells of other organs by the passage of a chemical substance of the nature of a ferment or proferment’ (Scott 1905). ‘The most striking morphological feature of the neuron is the tremendous accumulation within its cytoplasm of small granules associated with a well developed endoplasmic reticulum. The same type of association is found in the ergastoplasm of glandular cells... cells which sustain an intense protein production. In the nerve this activity is implicit in chromatolysis and to certain types of generalized stress. The rapid regeneration of axons and the peculiar damming up of axoplasm proximal to a ligature are also reflexions of a continuous and rapid protein synthesis in the perikaryon.... The fact that the structure of the Nissl substance is the same as that of the ergastoplasm in glandular cells means that future analysis... in such readily available cells as those of the pancreas and liver can be profitably applied to the nerve cell’ (Palay & Palade 1955). ‘Neurosecretion should not perhaps be used as a term to describe only the histochemically demonstrable secretory processes of nerves such as those of the hypothalamo-pituitary system. The analogies are sufficient to indicate that similar processes are involved in the production, transport and secretion of acetylcholine from other nerve endings. So these, too, may also be called neurosecretory nerves’ (Hebb 1959). ‘All neurons have a secretory function by which active substances are synthesized and released. Secretion may act over a short distance on specific chemical receptors or on distant receptors by way of the blood stream. Intermediary examples are the adrenergic neuro-effectors ending on smooth muscle. Neurosecretion may be produced all along the neuron or at the nerve endings. In all cases, it is stored within a membrane in vesicles which represent multimolecular quantal units of neurosecretion’ (De Robertis 1964).

Cytochemical studies of protein transport in the nervous system.

Abstract: The transport of materials within the nervous system has received much attention in recent years. Considerable information has accumulated concerning such subjects as the exchange of substances between the circulation and nervous tissue, the passage down axons of molecules and organelles originating in perikarya and the release and fate of neurotransmitters and neurosecretory agents at synapses and other neuron endings (see, for example, Wolstenholme & Porter 1968; Barondes 1969). Many investigations are underway on modulations of transport during nerve growth and regeneration and in tissue responding to injury or to other experimental alterations. However, numerous gaps remain. Of central importance to future analysis of intraneuronal transport will be the determination of details of the routes and mechanisms by which various components synthesized in the perikaryon become distributed throughout the cell. It is becoming increasingly clear that different components move along axons at quite different rates (see, for example, McEwen & Grafstein 1968). This heterogeneity may reflect the existence of a variety of intraaxonal transport pathways. Important clues derive from such work as the studies on microtubules reported by D. S. Smith in the present proceedings but much remains to be learned about possible compartmentalization of movement within axons. Similarly, the organization of perikarya must be further investigated. Neurons possess abundant rough endoplasmic reticulum, many free ribosomes, a well-developed Golgi apparatus and other features consonant with their intensive metabolic activity. Remarkably little is known, however, about most of the molecules synthesized within perikarya and about the division of labour among the organelles of the perikaryal cytoplasm.

The effect of undernutrition on the development of myelin in the rat central nervous system

Abstract: Newborn rats were segregated into litters of 6 and 22 pups. Undernourished groups were maintained for 21 and 53 days at which time a portion of each group was sacrificed and the remainder refed until 121 days. The amount of myelin isolated from the central nervous system was decreased in nutritionally deprived animals but there was little change in its chemical composition or intereference in the normal chemical maturation of the membrane. The only consistent change was a reduction in phosphatidyl ethanolamine plasmalogen. This deficit tended to be corrected by nutritional rehabilitation and was most complete in those animals refed ad lib. diets for the longest time periods prior to sacrifice. The relatively normal chemical composition of myelin obtained from undernourished animals differs from changes described in myelin membranes isolated from patients with destructive or degenerative diseases of the nervous system. This seems to be further evidence that the reduction in myelination in undernutrition is a result of decreased synthesis of the membrane.

Changes in the Nervous System and Musculature of Old Rats

Abstract: Changes in the nervous system and musculature of normal 34-month-old rats are described. Wallerian degeneration as well as segmental demyelination were observed in the peripheral nervous system, with changes more severe in the sciatic than in the brachial nerves. Signs of nerve-fibre degeneration were also seen in the cord and lower brain stem. The degenerative changes were usually mild, but in a number of animals there was severe degeneration of the gracile tract and lateral columns. Other changes in the nervous system included lipochrome pigment in nerve cells and other cellular elements throughout brain and cord, and eosinophilic bodies in the lower brain stem and cord. In some animals the ventricular system in the brain was dilated. Changes in the skeletal musculature were believed to represent neurogenic muscular atrophy secondary to changes in the nervous system.

Transport in the Central Nervous System

Abstract: Most of the prominent and important effects of narcotic analgesics on the body are a result of their action in the central nervous system (CNS). The sites and mechanisms of action of these drugs in the nervous system are unknown. One approach to identifiying a site or mechanism of action of a drug is to study its distribution within the responsive tissues. In the case of the narcotic analgesics the significance and specificity of sites of drug localization in the CNS can be evaluated by correlating the rise and fall of drug concentration at various sites with the onset and duration of pharmacological actions (for example, analgesia), by studying the effects of narcotic antagonists (for example, nalorphine or naloxone) on the distribution of the drug, and by determining the effects of tolerance development on the tissue concentrations of narcotic analgesics. This approach to identifying a site of narcotic action in the nervous system has proven to be unrewarding in the intact animal (for example, see Mule et al.,(1, 2, 7) Hug et al.,(3, 4) Johannesson et al.,(5, 6) and Chernov and Woods(8) and see Way and Adler(9) for earlier references). First, unique sites of localization were not detected. Second, changes in localization induced by nalorphine or tolerance development were small, often neither biologically nor statistically significant. Third, in the intact animal there are numerous factors that influence the uptake of drugs by the nervous system, and the reproducibility and interpretation of experiments thereby are made difficult. Finally, the techniques employed would not be likely to detect sites of localization at the cellular or subcellular levels.

On the innervation of the rat and pig adrenal cortex

Abstract: The innervation of the adrenal cortex of the rat and the pig is investigated with the electron microscope. Nerve fibers containing synaptic and two types of dense-cored vesicles come into contact with endocrine cells. There are no specialized pre- and postsynaptic membranes. The synaptic cleft is about 200 A wide. Generally the basement membrane between nerve and cell is absent. These observations are discussed on the base of more recent experimental findings. Small fibers having an average diameter of about 0.2 to 0.5 μ and containing only tubules and filaments are considered to represent parts of an afferent nervous system.

Sensory, motor, and autonomic dysfunction: The nervous system in familial dysautonomia

Abstract: FAMILIAL DYSAUTONOMIA is a complex and poorly understood disease which was first described in 1949 under the title, “Central autonomic dysfunction with defective‘ lacrimation.”l Since that time, additional clinical observations have led to the establishment of criteiia for diagnosk24 These criteria include autosomal recessive inheritance with Jewish parentage, defective lacrimation, vasomotor instabilities, poor temperature control, and episodic hyperhidrosis. In addition to abnormalities attributable to the field of action of the autonomic nervous system, there are sensory disturbances which include corneal anesthesia, indifference to pain, and impaired taste sensation. Indicators of neuromuscular dysfunction are poor coordination and absent or hypoactive deep tendon reflexes. Body growth is often retarded and mental development is slow. Pharmacologic and physiologic studies have amplified the clinical data and to some extent aided in understanding the disease.5-14 Reports of anatomic pathologic defects in dysautonomia have been very varied and, as in the case of pharmacologic and physiologic studies, have not permitted the development of a single unifying concept of this still perplexing disea~e.1,15-~0 Our studies of a 1-year-old child with familial dysautonomia have revealed findings, some of which have not been previously reported, which may help to clarify this disease and may aid in distinguishing it from other ill-understood clinical syndromes with certain similarities.21-23

Microscopic localization of cholinesterases in the nervous systems of the lobsters, Panulirus argus and Homarus americanus

Abstract: Using acetylthiocholine as substrate, microscopically localizable cholinesterase (ChE) activity is demonstrated in neural and glial elements of central and peripheral nervous systems of the lobsters, Panulirus argus and Homarus americanus. Moderate to very intense ChE activity occurs in all synaptic regions of the central ganglia and stomatogastric ganglion, in glial sheaths around neuron somata and peripheral nerve axons, and in cytoplasm of a few nerve cell bodies. Axons, identified as motor, contain extremely little ChE. The principal reaction in peripheral nerves occurs in sheath elements of sensory fibres; in most cases, much of the reaction is lost as the nerves lose the sheaths at the point of entry into brain.

The organization of the cerebral ganglion in the shore crab, Carcinus maenas. I. Morphology.

Abstract: The organization of the cerebral ganglion of the shore crab Carcinus maenas, is investigated by conventional histological and electronmicroscopic techniques. This study forms part of a comprehensive survey of the blood-brain interface, particularly interesting in this group, as decapod Crustacea are unusual among invertebrates in possessing an intracerebral blood supply. Apart from the intracerebral blood vessels, tissue organization is closely similar to that observed in insect central neural ganglia. The ganglion is surrounded by the neural lamella, an acellular connective tissue sheath, probably containing mucopolysaccharide and collagen. A layer of specialised glia, the perineurium, immediately underlies the neural lamella, and appears to contribute to its formation. Large glia occupying a conspicuous cortical zone below the perineurium may be involved in glycogen metabolism and storage. Further morphologically distinct glial types are observed associated with neurones and blood vessels, but all neuroglia within the ganglion are probably of common origin. Neurone cell bodies are generally situated peripherally in groups, and send axons into neuropil (synaptic) areas in the ganglion core. Large lacunae in the cortical region and narrower 20 nm clefts deeper in the ganglion, constitute the interstitial space, and contain deposits of fibrillar material. Possible physiological implications are discussed.

Histochemical localization of monoamines in the crab central nervous system.

Abstract: The localization of monoaminergic cells in the central nervous system of the crab Carcinus maenas was studied by the Falck-Hillarp fluorescence histochemical technique. Specific green fluorescence attributable to catecholamines was found in neurons and neuropile of eyestalk ganglia, brain, circumesophageal connectives and ganglia, and ventral ganglia. Specific yellow fluorescence attributable to 5-hydroxytryptamine was found in neurons of the brain and ventral ganglia.

Botulinum Toxin as a Tool for Research on the Nervous System

Abstract: In recent years there has been a great increase of interest in the mechanisms by which nerves transfer information to other nerves and to nonneural end organs. New chemical, pharmacological and physiological techniques have been developed to study the variety of neurotransmitter agents and mechanisms which exist in nature. Nevertheless, our knowledge of the sequence of events from synthesis of a transmitter through its ultimate effect at the innervated end-organ is incomplete for any given agent or synapse.

The Role of Sheath Cells in Glutamate Uptake by Insect Nerve Muscle Preparations

Abstract: Publisher Summary This chapter discusses the role of sheath cells in glutamate uptake by insect nerve muscle preparations Glutamic acid has also been recovered from perfusates of stimulated insect neuromuscular preparations Glutamate transport may have been such a mechanism Its persistence in the vertebrate nervous system possibly represents the remains of an old and universal neural process, may be as a general excitant More extensive studies on the role of glutamate and other amino acids in neural function of lower forms may contribute to the understanding of its role in the vertebrate nervous system Glutamate appears to be acting on the postjunctional membrane because its effectiveness in producing muscle contraction persists after denervation eliminates all neurally evoked action The chapter also discusses the evolutionary implications of the facilitated transport mechanism for glutamate in vertebrate nerve The excitatory neuromuscular transmitter in annelid worms appears to be acetylcholine as it is in vertebrates

The Circulatory System of Lymnaea Stagnalis (L.)

Abstract: The present study deals with the circulatory system of the pulmonate freshwater snail Lymnaea stagnalis. As, due to structural and functional complications (e.g., open system, both lung and skin respiration), the study of circulation in gastropods is difficult, the present investigations had, in many respects, a preliminary character. Three methods for studying the blood system were used. Two of these (radiography and corrosion preparations) easily permitted to establish the main course of the vascular system in several areas of the snail. The third method (histological preparations of ink injected animals) was used for most of the investigations. The latter comprise the following subjects: the main arterial and venous systems of the whole animal, the nervous tissue, the skin of the head and the kidney-lung complex. Furthermore, details are given on several organs and tissues such as the buccal mass and the gizzard, the penis, the digestive gland and the ovotestis. The open blood system of L. stagnalis shows remarkable differentiations. Several organs (gizzard, buccal mass) are internally vascularized. Muscular contractions assist in circulating the blood through these organs. Other organs have a complicated external vascular system (nervous system, glands). Intraspecific and interspecific differences occur frequently in the circulatory systems of pulmonates. This is illustrated by a discussion of the vascular system of the central nervous system. The general circulation cannot be sustained by the action of the heart alone. Muscular contractions (during locomotion especially those of the columellar muscle) are indispensable. Hence the detailed circulation dynamics are difficult to establish. The provision of the tissues with oxygen occurs in complicated ways. This is connected with the fact that L. stagnalis has two systems of respiration, viz., skin and lung respiration. The vascularization of the kidney is distinctly of a type which may be expected in animals producing hypotonic urine. The system most probably lacks a counter-current principle. The details of the vascular system of several organs and tissues (e.g., kidney-lung system, central nervous system) roughly accord with those in other pulmonates. The description of the vascular system of the skin of L. stagnalis is new, and it is supposed that this system occurs generally in gastropods. For a further appreciation of the function and the dynamics of the circulation in pulmonates ecological and ethological aspects must be taken into consideration.

Neural Coding in Olfactory Receptor Cells

Abstract: One goal which the electrophysiologist pursues is to discover the relation between inputs to a particular cell or section of the nervous system and the changes in temporal patterns of electrical neural activity which result from those inputs. Each pair of events which an animal can distinguish as being different must certainly be represented by a different pair of patterns of nerve cell activity. This must hold for the receptor cells (in the case of the vertebrate olfactory organ neurons) and for all units higher in the nervous hierarchy. Efferent connections from other parts of the nervous system to the olfactory receptor neurons are absent, hence we expect that changes in activity patterns of these neurons will depend only upon changes in smells presented to the animal, assuming a stable internal milieu. This assumption may not hold in fact since odorous stimulation may modify receptor function through sympathetic control of air flow through the nose and through circulating endocrine substances. If our goal were to be achieved completely we should be able to look at the activity of primary neurons and identify the stimulus or stimuli. That is what we mean when we say we understand the neural code.

The fine structure of neuroglia in the central nervous system of Nereid polychaetes.

Abstract: The principal supportive elements of the nereid central nervous system are non-neuronal cells that are referred to as supportive glia. Supportive glial cells form a conspicuous cortex in the nerve cord. The inner region of this cortex consists of closely packed processes and cell bodies of fibrous supportive glial cells that are arranged in concentric layers around the perimeter of the neuropile. The fibrous appearance of the glial cells results from dense bundles of cytoplasmic filaments. Many fibrous glial processes penetrate the neuropile and ramify among the neuronal elements. Larger, irregularly shaped cells are the chief supportive glial elements of the peripheral region of the cortex where they line the stromal sheath (neural lamella) and invest the neuronal perikarya with extensive concentric systems of lamellate processes. These glial cells usually possess a relatively undifferentiated cytoplasm with scattered glycogen granules, but occasionally have a well developed Golgi apparatus, endoplasmic reticulum and densely packed particulate glycogen. The supportive glia exhibits numerous desmosomes as well as 5-layered (“tight”) and 7-layered (“gap”) junctions. Interspersed among the supportive glial cells are non-neuronal cells referred to as granulocytes. These cells have abundant large, granular inclusions, electron lucent vesicles, plasmalemmal infoldings and microtubules. The granulocytes may be derived from undifferentiated glial cells or may represent coelomocytes that have invaded the nervous tissue.

Essentials of neurology

Abstract: Some general principles in neurology the symptoms and signs of disease in the nervous system investigation of the patient with neurological disease pain disorders of language and speech, apraxia and agnosia disorders of consciousness behaviour, memory, intellect, personality and their disorders the special senses the motor system the sensory system the automatic nervous system developmental, hereditary and degenerative disorders trauma and the nervous system infection and allergy and the nervous system demyelinating diseases neoplasms and the nervous system vascular disorders of the nervous system disorders of the lower motor neurone and voluntary muscles lesions of motor cranial nerves of spinal roots and of peripheral nerves metabolic disorders and the nervous system.

Relative importance of nervous control of cardiac output and arterial pressure

Abstract: The relative amounts of control that the nervous system exercises over arterial pressure versus cardiac output were studied in 41 dogs divided into 2 groups—intact dogs and dogs with all or most of the central nervous system destroyed. Responses of both groups were compared during 3 different types of circulatory stress: (1) opening and closing arteriovenous (A-V) fistulas, (2) massive infusion of blood, and (3) stimulation of muscle contraction. The results showed that the intact dogs controlled arterial pressure many times as effectively as did the dogs with the central nervous system destroyed. On the other hand, there was little difference in the control of cardiac output in the 2 groups of animals. Quantitative comparisons showed a feedback gain for nervous control of arterial pressure of −6.4 versus a feedback gain for control of cardiac output of −0.23. These experiments suggest that the nervous system is of much less importance for control of cardiac output than for control of arterial pressure.

Neuromuscular junctions on the muscle cells in the central nervous system of the leech, Hirudo medicinalis.

Abstract: The central nervous system of the leech is surrounded by fibrous tissue in which are contained muscle cells whose presumed function is to accommodate the length of the nervous system to coincide with changes in the length of the animal. In this paper a three-dimensional reconstruction of these muscles was described. Each neuromuscular junction consists of 5–50 neural terminals closely applied to the muscle. Furthermore, some morphologic evidence for synaptic interaction between terminals was obtained. We believe that this complex morphology of the terminals indicates that there is a relatively complex integrative mechanism for neuromuscular transmission at the periphery.

Topochemical aspects of nucleic acid and protein metabolism within the neuron-neuroglia unit of the spinal cord anterior horn

Abstract: — Using a two-wavelength modification of ultraviolet and visible cytospectro-photometric methods, the content of nucleic acids per cell was determined in neuronal cytoplasm and glial satellite cell-bodies from the spinal cord anterior horns in mice and rats. Mice which had been swimming for 3 and 4 h showed an increase in the content of RNA in the spinal motoneurons with no changes in the neuroglia. Stronger stimulation of the nervous system such as electrical skin irritation (20-40 V, approx. 40 impulses/min) for 5 min resulted in an increase of RNA in the motoneurons of rat spinal cord and a decrease in the surrounding glia. Exhausting actions upon the nervous system (60 min irritation of rat paws by the electrical current, acute clonic convulsions in rats injected with cardiazol (pentamethylenetetrazol, metrazol) or initial free motor activity after 3 weeks of restraint of mice) induced a marked decrease of RNA content throughout the whole neuron-neuroglia unit. After stimulation, return to normal amounts of RNA and protein was more rapid in glia than in neurons. After 1-3 days rest the level of RNA was normal in motoneurons, but a decrease in glial RNA was shown. These trace changes in the glia are believed to reflect an adaptation mechanism in the nervous system at the cellular level. The relationship between neuronal and glial compartments within the neuron-neuroglia unit is discussed; a supporting, homeostatic, secondary role of glial metabolism with respect to adequate reconstruction of neuronal metabolism is outlined.

Localization of monoamine-containing neurones in the nervous system ofStrophocheilus oblongus (Gastropoda)

Abstract: The histochemical fluorescence method of Falck and Hillarp was used to locate monoamine-containing neurones in the nervous system ofStrophocheilus, a Brazilian land snail. Green-fluorescing (catecholamines) cell bodies were found only in cerebral ganglia. Neuropiles of all ganglia contained many green-fluorescing fibers most of which appeared to enter from the periphery. Giant (up to 500 μ) non-fluorescing cells were seen in most ganglia of the suboesophageal mass. Green-fluorescing fibers surrounded, and apparently ended on, their axon hillocks and proximal segments of axons. Green-fluorescing sensory cells were seen in the eyeless tentacles. Cells fluorescing yellow (5-hydroxytryptamine) or yellow fading to green on exposure to ultraviolet light were found in cerebral, visceral and right palliai ganglia. Ligature of the cardiac nerve for 24 hrs resulted in an accumulation of yellow or “yellow green”-fluorescing masses in axons proximal to the constriction. The distribution of monoamine-containing neurones inStrophocheilus is rather similar to that found in other pulmonate molluscs such asHelix.

The brain specific proteins S 100 and 14.3.2 in experimental brain tumors of the rat.

Abstract: Primary tumors of the nervous system in rats induced by weekly administration of 6 mg/kg N-methylnitrosourea and spontaneous human brain tumors were investigated comparatively using immunoprecipitation technique. It is shown that two proteins antigenically identical with the specific glia proteins S100 and 14.3.2 are present in spontaneous as well as in experimental gliomas and schwannomas. These results demonstrate that the model of experimental tumors of the nervous system in rats is practicable for comparative morphological and biochemical studies of tumors of glial and schwann cell origin.