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Sample records for efferent callosal connections

  1. The afferent and efferent callosal connections of retinotopically defined areas in cat cortex

    SciTech Connect

    Segraves, M.A.; Rosenquist, A.C.

    1982-08-01

    We compared the callosal afferent and efferent connections of different retinotopic loci within a given visual cortical area as well as the connectivity patterns among similar retinotopic loci in different visual areas. Small injections (75 nl) of a mixture of horseradish peroxidase and (/sup 3/H)leucine were made through a recording pipette at injection sites identified by retinotopic mapping. A small locus of cortex within a callosally connected region had precise reciprocal connections with the homotopic locus in the contralateral hemisphere. This small locus also was callosally connected with a variable number of heterotopic loci. Both reciprocal and nonreciprocal heterotopic callosal connections were found. Homotopic and heterotopic connections appeared to have a high degree of retinotopic fidelity. Precisely homotopic connections were present not only between locations on the vertical meridian representations at the left and right area 17/18 borders but also, for example, between mirror-symmetrical points on the peripheral horizontal meridian representation in the left and right posteromedial lateral suprasylvian areas. In several experiments, we found that both callosal neurons and terminals in the homotopic cortex were grouped into two to three distinct clusters ranging from 600 to 900 micrometers in width. Callosal neurons with homotopic connections were primarily pyramidal cells in lower layer III and upper layer IV. Outside of areas 17 and 18, there was a significant number of pyramidal and fusiform-shaped callosal neurons in layers V and VI. The majority of callosal terminals were located in layers II, III, and IV.

  2. Visual interhemispheric communication and callosal connections of the occipital lobes.

    PubMed

    Berlucchi, Giovanni

    2014-07-01

    Callosal connections of the occipital lobes, coursing in the splenium of the corpus callosum, have long been thought to be crucial for interactions between the cerebral hemispheres in vision in both experimental animals and humans. Yet the callosal connections of the temporal and parietal lobes appear to have more important roles than those of the occipital callosal connections in at least some high-order interhemispheric visual functions. The partial intermixing and overlap of temporal, parietal and occipital callosal connections within the splenium has made it difficult to attribute the effects of splenial pathological lesions or experimental sections to splenial components specifically related to select cortical areas. The present review describes some current contributions from the modern techniques for the tracking of commissural fibers within the living human brain to the tentative assignation of specific visual functions to specific callosal tracts, either occipital or extraoccipital.

  3. Development of callosal connections in the sensorimotor cortex of the hamster.

    PubMed

    Norris, C R; Kalil, K

    1992-12-01

    To investigate the development of corpus callosal connectivity in the hamster sensorimotor cortex, we have used the sensitive axonal tracer 1,1 dioctadecyl-3,3,3',3', tetramethylindocarbocyanine perchlorate (DiI), which was injected either in vivo or in fixed brains of animals 3-6 days postnatal. First, to study changes in the overall distribution of developing callosal afferents we made large injections of DiI into the corpus callosal tract. We found that the anterogradely labeled callosal axons formed a patchy distribution in the contralateral sensorimotor cortex, which was similar to the pattern of adult connectivity described in earlier studies of the rodent corpus callosum. This result stands in contrast to previous retrograde studies of developing callosal connectivity which showed that the distribution of callosal neurons early in development is homogeneous and that the mature, patchy distribution arises later, primarily as a result of the retraction of exuberant axons. The initial patchy distribution of callosal axon growth into the sensorimotor cortex described in the present study suggests that exuberant axons destined to be eliminated do not enter the cortex. In addition, small injections of DiI into developing cortex resulted in homotopic patterns of callosal topography in which reciprocal regions of sensorimotor cortex are connected, as has been shown in the adult. Second, to study the radial growth of callosal afferents we followed the extension of individual callosal axons into the developing cortex. We found that callosal axons began to invade the contralateral cortex on about postnatal day 3, with little or no waiting period in the callosal tract. Callosal afferents then advanced steadily through the cortex, never actually invading the cortical plate but extending into layers on the first day that they could be distinguished from the cortical plate. The majority of callosal axons grew radially through the cortex and did not exhibit substantial

  4. Efferent connections of the septal area in the pigeon.

    PubMed

    Krayniak, P F; Siegel, A

    1978-01-01

    The efferent connections of the septum in the pigeon were studied with the use of anterograde (3H-leucine autoradiography) and retrograde (horseradish peroxidase histochemistry) transport methods. It was observed that the dorsal septum projects to the lateral hypothalamus, portions of the periventricular hypothalamus, dorsomedial thalamus and midbrain reticular formation. Fibers from the ventral half of the septum (i.e., nucleus of the diagonal band) project to medial and lateral sectors of the hypothalamus, dorsomedial thalamus, lateral habenular nucleus and midbrain tegmentum. In addition, fibers originating from this region also project to the hippocampal and parahippocampal cortices.

  5. Investigating the functional role of callosal connections with dynamic causal models.

    PubMed

    Stephan, Klaas E; Penny, Will D; Marshall, John C; Fink, Gereon R; Friston, Karl J

    2005-12-01

    The anatomy of the corpus callosum has been described in considerable detail. Tracing studies in animals and human postmortem experiments are currently complemented by diffusion-weighted imaging, which enables noninvasive investigations of callosal connectivity to be conducted. In contrast to the wealth of anatomical data, little is known about the principles by which interhemispheric integration is mediated by callosal connections. Most importantly, we lack insights into the mechanisms that determine the functional role of callosal connections in a context-dependent fashion. These mechanisms can now be disclosed by models of effective connectivity that explain neuroimaging data from paradigms that manipulate interhemispheric interactions. In this article, we demonstrate that dynamic causal modeling (DCM), in conjunction with Bayesian model selection (BMS), is a powerful approach to disentangling the various factors that determine the functional role of callosal connections. We first review the theoretical foundations of DCM and BMS before demonstrating the application of these techniques to empirical data from a single subject.

  6. Evolutionary Plasticity of Habenular Asymmetry with a Conserved Efferent Connectivity Pattern

    PubMed Central

    Guerrero, Néstor; Meynard, Margarita M.; Palma, Karina; Concha, Miguel L.

    2012-01-01

    The vertebrate habenulae (Hb) is an evolutionary conserved dorsal diencephalic nuclear complex that relays information from limbic and striatal forebrain regions to the ventral midbrain. One key feature of this bilateral nucleus is the presence of left-right differences in size, cytoarchitecture, connectivity, neurochemistry and/or gene expression. In teleosts, habenular asymmetry has been associated with preferential innervation of left-right habenular efferents into dorso-ventral domains of the midbrain interpeduncular nucleus (IPN). However, the degree of conservation of this trait and its relation to the structural asymmetries of the Hb are currently unknown. To address these questions, we performed the first systematic comparative analysis of structural and connectional asymmetries of the Hb in teleosts. We found striking inter-species variability in the overall shape and cytoarchitecture of the Hb, and in the frequency, strength and to a lesser degree, laterality of habenular volume at the population level. Directional asymmetry of the Hb was either to the left in D. rerio, E. bicolor, O. latipes, P. reticulata, B. splendens, or to the right in F. gardneri females. In contrast, asymmetry was absent in P. scalare and F. gardneri males at the population level, although in these species the Hb displayed volumetric asymmetries at the individual level. Inter-species variability was more pronounced across orders than within a single order, and coexisted with an overall conserved laterotopic representation of left-right habenular efferents into dorso-ventral domains of the IPN. These results suggest that the circuit design involving the Hb of teleosts promotes structural flexibility depending on developmental, cognitive and/or behavioural pressures, without affecting the main midbrain connectivity output, thus unveiling a key conserved role of this connectivity trait in the function of the circuit. We propose that ontogenic plasticity in habenular morphogenesis

  7. Midbrain periaqueductal grey region in the cat has afferent and efferent connections with solitary tract nuclei.

    PubMed

    Bandler, R; Tork, I

    1987-02-10

    Wheat germ agglutinin-horseradish peroxidase (WGA-HRP) injections were made at the same sites within the midbrain periaqueductal grey region (PAG) of the cat at which microinjections of excitatory amino acids had previously elicited the set of autonomic and somatic reactions (i.e. pupil dilatation, piloerection, retraction of the ears, arching of the back, hissing, howling and growling) known as the 'defence reaction'. The WGA-HRP injections revealed that this PAG region has an extensive set of afferent and efferent connections with solitary tract nuclei (NTS). Within the NTS the majority of labelled neurons were distributed, in approximately equal numbers, in the ipsilateral medial solitary nucleus (SM) and the ipsilateral and the contralateral ventrolateral solitary nuclei (SVL). The densest anterograde labelling was found in the ipsilateral SM, with lighter anterograde labelling in the contralateral SM and bilaterally in the commissural solitary nucleus and SVL. The described connections between the defence region of the PAG and the NTS not only provide a new anatomical basis for cardiovascular and respiratory components of the reaction, but also add to the evidence that, in addition to the hypothalamus, the PAG is an important integrating center for the autonomic and somatic elements of the defence reaction. PMID:2436102

  8. Efferent connections of the rostral linear nucleus of the ventral tegmental area in the rat.

    PubMed

    Del-Fava, F; Hasue, R H; Ferreira, J G P; Shammah-Lagnado, S J

    2007-03-30

    The ventral tegmental area (VTA) is crucially involved in brain reward, motivated behaviors, and drug addiction. This district is functionally heterogeneous, and studying the connections of its different parts may contribute to clarify the structural basis of intra-VTA functional specializations. Here, the efferents of the rostral linear nucleus (RLi), a midline VTA component, were traced in rats with the Phaseolus vulgaris leucoagglutinin (PHA-L) technique. The results show that the RLi heavily innervates the olfactory tubercle (mainly the polymorph layer) and the ventrolateral part of the ventral pallidum, but largely avoids the accumbens. The RLi also sends substantial projections to the magnocellular preoptic nucleus, lateral hypothalamus, central division of the mediodorsal thalamic nucleus, lateral part of the lateral habenula and supraoculomotor region, and light projections to the prefrontal cortex, basolateral amygdala, and dorsal raphe nucleus. A similar set of projections was observed after injections in rostromedial VTA districts adjacent to RLi, but these districts also send major outputs to the lateral ventral striatum. Overall, the data suggest that the RLi is a distinct VTA component in that it projects primarily to pallidal regions of the olfactory tubercle and to their diencephalic targets, the central division of the mediodorsal thalamic nucleus and the lateral part of the lateral habenula. Because the rat RLi reportedly contains a lower density of dopaminergic neurons as compared with most of the VTA, its unusual projections may reflect a non-dopaminergic, putative GABAergic, phenotype, and this distinctive cell population seemingly extends beyond RLi boundaries into the laterally adjacent VTA. By being connected to the central division of the mediodorsal thalamic nucleus (directly and via ventral striatopallidal system) and to the magnocellular preoptic nucleus, the RLi and its surroundings may play a role in olfactory-guided behaviors, which

  9. SUBCORTICAL CONNECTIONS OF THE PERIRHINAL, POSTRHINAL, AND ENTORHINAL CORTICES OF THE RAT. II. EFFERENTS

    PubMed Central

    Agster, Kara L.; Pereira, Inês Tomás; Saddoris, Michael P.; Burwell, Rebecca D.

    2016-01-01

    This is the second of two studies detailing the subcortical connections of the perirhinal (PER), the postrhinal (POR) and entorhinal (EC) cortices of the rat. In the present study, we analyzed the subcortical efferents of the rat PER areas 35 and 36, POR, and the lateral and medial entorhinal areas (LEA and MEA). Anterograde tracers were injected into these five regions, and the resulting density of fiber labeling was quantified in an extensive set of subcortical structures. Density and topography of fiber labeling were quantitatively assessed in 36 subcortical areas, including olfactory structures, claustrum, amygdala nuclei, septal nuclei, basal ganglia, thalamic nuclei, and hypothalamic structures. In addition to reporting the density of labeled fibers, we incorporated a new method for quantifying the size of anterograde projections that takes into account the volume of the target subcortical structure as well as the density of fiber labeling. The PER, POR and EC displayed unique patterns of projections to subcortical areas. Interestingly, all regions examined provided strong input to the basal ganglia, although the projections arising in the PER and LEA were stronger and more widespread. PER areas 35 and 36 exhibited similar pattern of projections with some differences. PER area 36 projects more heavily to the lateral amygdala and much more heavily to thalamic nuclei including the lateral posterior nucleus, the posterior complex, and the nucleus reuniens. Area 35 projects more heavily to olfactory structures. The LEA provides the strongest and most widespread projections to subcortical structures including all those targeted by the PER as well as the medial and posterior septal nuclei. POR shows fewer subcortical projections overall, but contributes substantial input to the lateral posterior nucleus of the thalamus. The MEA projections are even weaker. Our results suggest that the PER and LEA have greater influence over olfactory, amygdala, and septal nuclei

  10. Functional magnetic resonance imaging connectivity analyses reveal efference-copy to primary somatosensory area, BA2.

    PubMed

    Cui, Fang; Arnstein, Dan; Thomas, Rajat Mani; Maurits, Natasha M; Keysers, Christian; Gazzola, Valeria

    2014-01-01

    Some theories of motor control suggest efference-copies of motor commands reach somatosensory cortices. Here we used functional magnetic resonance imaging to test these models. We varied the amount of efference-copy signal by making participants squeeze a soft material either actively or passively. We found electromyographical recordings, an efference-copy proxy, to predict activity in primary somatosensory regions, in particular Brodmann Area (BA) 2. Partial correlation analyses confirmed that brain activity in cortical structures associated with motor control (premotor and supplementary motor cortices, the parietal area PF and the cerebellum) predicts brain activity in BA2 without being entirely mediated by activity in early somatosensory (BA3b) cortex. Our study therefore provides valuable empirical evidence for efference-copy models of motor control, and shows that signals in BA2 can indeed reflect an input from motor cortices and suggests that we should interpret activations in BA2 as evidence for somatosensory-motor rather than somatosensory coding alone.

  11. Functional Magnetic Resonance Imaging Connectivity Analyses Reveal Efference-Copy to Primary Somatosensory Area, BA2

    PubMed Central

    Cui, Fang; Arnstein, Dan; Thomas, Rajat Mani; Maurits, Natasha M.; Keysers, Christian; Gazzola, Valeria

    2014-01-01

    Some theories of motor control suggest efference-copies of motor commands reach somatosensory cortices. Here we used functional magnetic resonance imaging to test these models. We varied the amount of efference-copy signal by making participants squeeze a soft material either actively or passively. We found electromyographical recordings, an efference-copy proxy, to predict activity in primary somatosensory regions, in particular Brodmann Area (BA) 2. Partial correlation analyses confirmed that brain activity in cortical structures associated with motor control (premotor and supplementary motor cortices, the parietal area PF and the cerebellum) predicts brain activity in BA2 without being entirely mediated by activity in early somatosensory (BA3b) cortex. Our study therefore provides valuable empirical evidence for efference-copy models of motor control, and shows that signals in BA2 can indeed reflect an input from motor cortices and suggests that we should interpret activations in BA2 as evidence for somatosensory-motor rather than somatosensory coding alone. PMID:24416222

  12. Efferent and afferent connections of the olfactory bulb and prepiriform cortex in the pigeon (Columba livia).

    PubMed

    Atoji, Yasuro; Wild, J Martin

    2014-06-01

    Although olfaction in birds is known to be involved in a variety of behaviors, there is comparatively little detailed information on the olfactory brain. In the pigeon brain, the olfactory bulb (OB) is known to project to the prepiriform cortex (CPP), piriform cortex (CPi), and dorsolateral corticoid area (CDL), which together are called the olfactory pallium, but centrifugal pathways to the OB have not been fully explored. Fiber connections of CPi and CDL have been reported, but those of other olfactory pallial nuclei remain unknown. The present study examines the fiber connections of OB and CPP in pigeons to provide a more detailed picture of their connections using tract-tracing methods. When anterograde and retrograde tracers were injected in OB, projections to a more extensive olfactory pallium were revealed, including the anterior olfactory nucleus, CPP, densocellular part of the hyperpallium, tenia tecta, hippocampal continuation, CPi, and CDL. OB projected commissural fibers to the contralateral OB but did not receive afferents from the contralateral olfactory pallium. When tracers were injected in CPP, reciprocal ipsilateral connections with OB and nuclei of the olfactory pallium were observed, and CPP projected to the caudolateral nidopallium and the limbic system, including the hippocampal formation, septum, lateral hypothalamic nucleus, and lateral mammillary nucleus. These results show that the connections of OB have a wider distribution throughout the olfactory pallium than previously thought and that CPP provides a centrifugal projection to the OB and acts as a relay station to the limbic system.

  13. Septal complex of the telencephalon of lizards: III. Efferent connections and general discussion.

    PubMed

    Font, C; Lanuza, E; Martinez-Marcos, A; Hoogland, P V; Martinez-Garcia, F

    1998-11-30

    The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combining retrograde and anterograde neuroanatomical tracing. The results confirm the classification of septal nuclei into three main divisions. The nuclei composing the central septal division (anterior, lateral, medial, dorsolateral, and ventrolateral nuclei) displayed differential projections to the basal telencephalon, preoptic and anterior hypothalamus, lateral hypothalamic area, dorsal hypothalamus, mammillary complex, dorsomedial anterior thalamus, ventral tegmental area, interpeduncular nucleus, raphe nucleus, torus semicircularis pars laminaris, reptilian A8 nucleus/substantia nigra and central gray. For instance, only the medial septal nucleus projected substantially to the thalamus whereas the anterior septum was the only nucleus projecting to the caudal midbrain including the central gray. The anterior and lateral septal nuclei also differ in the way in which their projection to the preoptic hypothalamus terminated. The midline septal division is composed of the dorsal septal nucleus, nucleus septalis impar and nucleus of the posterior pallial commissure. The latter two nuclei projected to the lateral habenula and, at least the nucleus of the posterior pallial commissure, to the mammillary complex. The dorsal septal nucleus projected to the preoptic and periventricular hypothalamus and the anterior thalamus, but its central part seemed to project to the caudal midbrain (up to the midbrain central gray). Finally, the ventromedial septal division (ventromedial septal nucleus) showed a massive projection to the anterior and the lateral tuberomammillary hypothalamus. Data on the connections of the septum of P. hispanica and Gecko gekko are discussed from a comparative point of view and used for better understanding of the functional anatomy of the tetrapodian septum.

  14. A center's callosities.

    PubMed

    Adams, B B; Lucky, A W

    2001-02-01

    We present a case report of a 14-year-old white male who developed hyperkeratotic plaques on the distal aspects of 2 toes. He was referred by his primary care physician for the treatment of onychomycosis. With questioning, the patient stated that he played center for his high school basketball team. After physical examination, he was diagnosed with callosities caused by his basketball activities. Proper nail hygiene and wearing of larger footwear resulted in improvement of his callosities. Sports-related cutaneous injuries should be included in the differential diagnosis of nail and toe abnormalities.

  15. Callosal Connections of Primary Visual Cortex Predict the Spatial Spreading of Binocular Rivalry Across the Visual Hemifields

    PubMed Central

    Genç, Erhan; Bergmann, Johanna; Tong, Frank; Blake, Randolph; Singer, Wolf; Kohler, Axel

    2011-01-01

    In binocular rivalry, presentation of different images to the separate eyes leads to conscious perception alternating between the two possible interpretations every few seconds. During perceptual transitions, a stimulus emerging into dominance can spread in a wave-like manner across the visual field. These traveling waves of rivalry dominance have been successfully related to the cortical magnification properties and functional activity of early visual areas, including the primary visual cortex (V1). Curiously however, these traveling waves undergo a delay when passing from one hemifield to another. In the current study, we used diffusion tensor imaging (DTI) to investigate whether the strength of interhemispheric connections between the left and right visual cortex might be related to the delay of traveling waves across hemifields. We measured the delay in traveling wave times (ΔTWT) in 19 participants and repeated this test 6 weeks later to evaluate the reliability of our behavioral measures. We found large interindividual variability but also good test–retest reliability for individual measures of ΔTWT. Using DTI in connection with fiber tractography, we identified parts of the corpus callosum connecting functionally defined visual areas V1–V3. We found that individual differences in ΔTWT was reliably predicted by the diffusion properties of transcallosal fibers connecting left and right V1, but observed no such effect for neighboring transcallosal visual fibers connecting V2 and V3. Our results demonstrate that the anatomical characteristics of topographically specific transcallosal connections predict the individual delay of interhemispheric traveling waves, providing further evidence that V1 is an important site for neural processes underlying binocular rivalry. PMID:22162968

  16. The claustrum of the ferret: afferent and efferent connections to lower and higher order visual cortical areas

    PubMed Central

    Patzke, Nina; Innocenti, Giorgio M.; Manger, Paul R.

    2014-01-01

    The claustrum, a subcortical telencephalic structure, is known to be reciprocally interconnected to almost all cortical regions; however, a systematic analysis of claustrocortical connectivity with physiologically identified lower and higher order visual cortical areas has not been undertaken. In the current study we used biotinylated dextran amine to trace the connections of the ferret claustrum with lower (occipital areas 17, 18, 19 and 21) and higher (parietal and temporal areas posterior parietal caudal visual area (PPc), posterior parietal rostral visual area (PPr), 20a, 20b, anterior ectosylvian visual area (AEV)) order visual cortical areas. No connections between the claustrum and area 17 were observed. Occipital visual areas 18, 19 and 21 revealed a reciprocal connectivity mainly to the caudal part of the claustrum. After injection into parietal areas PPc and PPr labeled neurons and terminals were found throughout almost the entire rostrocaudal extent of the dorsal claustrum. Area 20b revealed reciprocal connections mainly to the caudal-ventral claustrum, although some labeled neurons and terminals were observed in the dorso-central claustrum. No projection from the claustrum to areas AEV and 20a could be observed, though projections from AEV and 20a to the claustrum were found. Only injections placed in areas PPr and AEV resulted in anterogradely labeled terminals in the contralateral claustrum. Our results suggest that lower order visual areas have clearly defined connectivity zones located in the caudal claustrum, whereas higher order visual areas, even if not sending and/or receiving projections from the entire claustrum, show a more widespread connectivity. PMID:24616671

  17. Evolutionarily conserved organization of the dopaminergic system in lamprey: SNc/VTA afferent and efferent connectivity and D2 receptor expression.

    PubMed

    Pérez-Fernández, Juan; Stephenson-Jones, Marcus; Suryanarayana, Shreyas M; Robertson, Brita; Grillner, Sten

    2014-12-01

    The dopaminergic system influences motor behavior, signals reward and novelty, and is an essential component of the basal ganglia in all vertebrates including the lamprey, one of the phylogenetically oldest vertebrates. The intrinsic organization and function of the lamprey basal ganglia is highly conserved. For instance, the direct and indirect pathways are modulated through dopamine D1 and D2 receptors in lamprey and in mammals. The nucleus of the tuberculum posterior, a homologue of the substantia nigra pars compacta (SNc)/ventral tegmental area (VTA) is present in lamprey, but only scarce data exist about its connectivity. Likewise, the D2 receptor is expressed in the striatum, but little is known about its localization in other brain areas. We used in situ hybridization and tracer injections, both in combination with tyrosine hydroxylase immunohistochemistry, to characterize the SNc/VTA efferent and afferent connectivity, and to relate its projection pattern with D2 receptor expression in particular. We show that most features of the dopaminergic system are highly conserved. As in mammals, the direct pallial (cortex in mammals) input and the basal ganglia connectivity with the SNc/VTA are present as part of the evaluation system, as well as input from the tectum as the evolutionary basis for salience/novelty detection. Moreover, the SNc/VTA receives sensory information from the olfactory bulbs, optic tectum, octavolateral area, and dorsal column nucleus, and it innervates, apart from the nigrostriatal pathway, several motor-related areas. This suggests that the dopaminergic system also contributes to the control of different motor centers at the brainstem level.

  18. Voltage-sensitive-dye imaging of microstimulation-evoked neural activity through intracortical horizontal and callosal connections in cat visual cortex

    NASA Astrophysics Data System (ADS)

    Suzurikawa, Jun; Tani, Toshiki; Nakao, Masayuki; Tanaka, Shigeru; Takahashi, Hirokazu

    2009-12-01

    Recently, intrinsic signal optical imaging has been widely used as a routine procedure for visualizing cortical functional maps. We do not, however, have a well-established imaging method for visualizing cortical functional connectivity indicating spatio-temporal patterns of activity propagation in the cerebral cortex. In the present study, we developed a novel experimental setup for investigating the propagation of neural activities combining the intracortical microstimulation (ICMS) technique with voltage sensitive dye (VSD) imaging, and demonstrated the feasibility of this setup applying to the measurement of time-dependent intra- and inter-hemispheric spread of ICMS-evoked excitation in the cat visual cortices, areas 17 and 18. A microelectrode array for the ICMS was inserted with a specially designed easy-to-detach electrode holder around the 17/18 transition zones (TZs), where the left and right hemispheres were interconnected via the corpus callosum. The microelectrode array was stably anchored in agarose without any holder, which enabled us to visualize evoked activities even in the vicinity of penetration sites as well as in a wide recording region that covered a part of both hemispheres. The VSD imaging could successfully visualize ICMS-evoked excitation and subsequent propagation in the visual cortices contralateral as well as ipsilateral to the ICMS. Using the orientation maps as positional references, we showed that the activity propagation patterns were consistent with previously reported anatomical patterns of intracortical and interhemispheric connections. This finding indicates that our experimental system can serve for the investigation of cortical functional connectivity.

  19. Tau Pathology Spread in PS19 Tau Transgenic Mice Following Locus Coeruleus (LC) Injections of Synthetic Tau Fibrils is Determined by the LC’s Afferent and Efferent Connections

    PubMed Central

    Iba, Michiyo; McBride, Jennifer D.; Guo, Jing L.; Zhang, Bin; Trojanowski, John Q.; Lee, Virginia M.-Y.

    2015-01-01

    Filamentous tau inclusions are hallmarks of Alzheimer’s disease (AD) and other neurodegenerative tauopathies. An increasing number of studies implicate the cell-to-cell propagation of tau pathology in the progression of tauopathies. We recently showed [25] that inoculation of preformed synthetic tau fibrils (tau PFFs) into the hippocampus of young transgenic (Tg) mice (PS19) overexpressing human P301S mutant tau induced robust tau pathology in anatomically connected brain regions including the locus coeruleus (LC). Since Braak and colleagues hypothesized that the LC is the first brain structure to develop tau lesions and since LC has widespread connections throughout the CNS, LC neurons could be the critical initiators of the stereotypical spreading of tau pathology through connectome-dependent transmission of pathological tau in AD. Here, we report that injections of tau PFFs into the LC of PS19 mice induced propagation of tau pathology to major afferents and efferents of the LC. Notably, tau pathology propagated along LC efferent projections was localized not only to axon terminals but also to neuronal perikarya, suggesting transneuronal transfer of templated tau pathology to neurons receiving LC projections. Further, brainstem neurons giving rise to major LC afferents also developed perikaryal tau pathology. Surprisingly, while tangle bearing neurons degenerated in the LC ipsilateral to the injection site starting 6 months post-injection, no neuron loss was seen in the contralateral LC wherein tangle bearing neurons gradually cleared tau pathology by 6–12 months post-injection. However, the spreading pattern of tau pathology observed in our LC-injected mice is different from that in AD brains since hippocampus and entorhinal cortex, which are affected in early stages of AD, were largely spared of tau inclusions in our model. Thus, while our study tested critical aspects of the Braak hypothesis of tau pathology spread, this novel mouse model provides unique

  20. Electrophysiological Correlates of Morphological Neuroplasticity in Human Callosal Dysgenesis

    PubMed Central

    Lazarev, Vladimir V.; de Carvalho Monteiro, Myriam; Vianna-Barbosa, Rodrigo; deAzevedo, Leonardo C.; Lent, Roberto; Tovar-Moll, Fernanda

    2016-01-01

    In search for the functional counterpart of the alternative Probst and sigmoid bundles, considered as morphological evidence of neuroplasticity in callosal dysgenesis, electroencephalographic (EEG) coherence analysis was combined with high resolution and diffusion tensor magnetic resonance imaging. Data of two patients with callosal agenesis, plus two with typical partial dysgenesis with a remnant genu, and one atypical patient with a substantially reduced genu were compared to those of fifteen neurotypic controls. The interhemispheric EEG coherence between homologous nontemporal brain regions corresponded to absence or partial presence of callosal connections. A generalized coherence reduction was observed in complete acallosal patients, as well as coherence preservation in the anterior areas of the two patients with a remnant genu. jThe sigmoid bundles found in three patients with partial dysgenesis correlated with augmented EEG coherence between anterior regions of one hemisphere and posterior regions of the other. These heterologous (crossed) interhemispheric connections were asymmetric in both imaging and EEG patterns, with predominance of the right-anterior-to-left-posterior connections over the mirror ones. The Probst bundles correlated with higher intrahemispheric long-distance coherence in all patients. The significant correlations observed for the delta, theta and alpha bands indicate that these alternative pathways are functional, although the neuropsychological nature of this function is still unknown. PMID:27055255

  1. Are there efferent synapses in fish taste buds?

    PubMed

    Reutter, Klaus; Witt, Martin

    2004-12-01

    In fish, nerve fibers of taste buds are organized within the bud's nerve fiber plexus. It is located between the sensory epithelium consisting of light and dark elongated cells and the basal cells. It comprises the basal parts and processes of light and dark cells that intermingle with nerve fibers, which are the dendritic endings of the taste sensory neurons belonging to the cranial nerves VII, IX or X. Most of the synapses at the plexus are afferent; they have synaptic vesicles on the light (or dark) cells side, which is presynaptic. In contrast, the presumed efferent synapses may be rich in synaptic vesicles on the nerve fibers (presynaptic) side, whereas the cells (postsynaptic) side may contain a subsynaptic cistern; a flat compartment of the smooth endoplasmic reticulum. This structure is regarded as a prerequisite of a typical efferent synapse, as occurring in cochlear and vestibular hair cells. In fish taste buds, efferent synapses are rare and were found only in a few species that belong to different taxa. The significance of efferent synapses in fish taste buds is not well understood, because efferent connections between the gustatory nuclei of the medulla with taste buds are not yet proved.

  2. Are there efferent synapses in fish taste buds?

    PubMed

    Reutter, Klaus; Witt, Martin

    2004-12-01

    In fish, nerve fibers of taste buds are organized within the bud's nerve fiber plexus. It is located between the sensory epithelium consisting of light and dark elongated cells and the basal cells. It comprises the basal parts and processes of light and dark cells that intermingle with nerve fibers, which are the dendritic endings of the taste sensory neurons belonging to the cranial nerves VII, IX or X. Most of the synapses at the plexus are afferent; they have synaptic vesicles on the light (or dark) cells side, which is presynaptic. In contrast, the presumed efferent synapses may be rich in synaptic vesicles on the nerve fibers (presynaptic) side, whereas the cells (postsynaptic) side may contain a subsynaptic cistern; a flat compartment of the smooth endoplasmic reticulum. This structure is regarded as a prerequisite of a typical efferent synapse, as occurring in cochlear and vestibular hair cells. In fish taste buds, efferent synapses are rare and were found only in a few species that belong to different taxa. The significance of efferent synapses in fish taste buds is not well understood, because efferent connections between the gustatory nuclei of the medulla with taste buds are not yet proved. PMID:16217620

  3. Expression of Arabidopsis callose synthase 5 results in callose accumulation and cell wall permeability alteration.

    PubMed

    Xie, Bo; Deng, Yunfei; Kanaoka, Masahiro M; Okada, Kiyotaka; Hong, Zonglie

    2012-02-01

    Callose is the major polysaccharide present in the callose wall of developing microspores and the growing pollen tube wall. It is also an essential component of other specialized cell walls and its synthesis can be induced by pathogen infection, wounding and environmental cues. Among the 12 callose synthase genes (CalS) present in the Arabidopsis genome, CalS5 plays the predominant role in the synthesis of the callose wall, callose plugs and pollen tube wall. When expressed as a GFP-tagged protein in cultured tobacco BY-2 cells, CalS5 was found to be present in the plasma membrane and the Golgi-related endomembranes. Unlike the cell plate-specific CalS1 isozyme, CalS5 was not concentrated to the cell plate at cytokinesis. Expression of CalS5 resulted in callose accumulation only in the cell wall of BY-2 cells. The fact that no callose was found in the endomembranes suggests that CalS5 is not functional in that compartment. These cells exhibited a decreased plasmolysis rate in hypotonic solutions and an increased cytolysis rate in hypertonic conditions. This study demonstrates that an artificial callose wall could be synthesized by expressing a callose synthase enzyme. PMID:22195570

  4. Expression of Arabidopsis callose synthase 5 results in callose accumulation and cell wall permeability alteration.

    PubMed

    Xie, Bo; Deng, Yunfei; Kanaoka, Masahiro M; Okada, Kiyotaka; Hong, Zonglie

    2012-02-01

    Callose is the major polysaccharide present in the callose wall of developing microspores and the growing pollen tube wall. It is also an essential component of other specialized cell walls and its synthesis can be induced by pathogen infection, wounding and environmental cues. Among the 12 callose synthase genes (CalS) present in the Arabidopsis genome, CalS5 plays the predominant role in the synthesis of the callose wall, callose plugs and pollen tube wall. When expressed as a GFP-tagged protein in cultured tobacco BY-2 cells, CalS5 was found to be present in the plasma membrane and the Golgi-related endomembranes. Unlike the cell plate-specific CalS1 isozyme, CalS5 was not concentrated to the cell plate at cytokinesis. Expression of CalS5 resulted in callose accumulation only in the cell wall of BY-2 cells. The fact that no callose was found in the endomembranes suggests that CalS5 is not functional in that compartment. These cells exhibited a decreased plasmolysis rate in hypotonic solutions and an increased cytolysis rate in hypertonic conditions. This study demonstrates that an artificial callose wall could be synthesized by expressing a callose synthase enzyme.

  5. Complete callosal disconnection after closed head injury.

    PubMed

    Vuilleumier, P; Assal, G

    1995-02-01

    We report a patient with complete callosal disconnection syndrome after severe closed head injury. MRI showed a complete destruction of the corpus callosum throughout its length. Although traumatic callosal lesions are a frequent finding in autopsy studies, as well as in some recent MRI studies, clinical signs of callosal disconnection are rarely observed after head injuries and a complete disconnection syndrome has not been reported yet. This case study and the review of other reported cases suggest that posttraumatic callosal disconnection is probably often overlooked. Our patient had also a severe memory disorder that might be partly related to the bilateral involvement of the fornix, as this structure is closely adjacent to the posterior corpus callosum, and was also shown by MRI to be very probably damaged.

  6. Vestibular efferent neurons project to the flocculus

    NASA Technical Reports Server (NTRS)

    Shinder, M. E.; Purcell, I. M.; Kaufman, G. D.; Perachio, A. A.

    2001-01-01

    A bilateral projection from the vestibular efferent neurons, located dorsal to the genu of the facial nerve, to the cerebellar flocculus and ventral paraflocculus was demonstrated. Efferent neurons were double-labeled by the unilateral injections of separate retrograde tracers into the labyrinth and into the floccular and ventral parafloccular lobules. Efferent neurons were found with double retrograde tracer labeling both ipsilateral and contralateral to the sites of injection. No double labeling was found when using a fluorescent tracer with non-fluorescent tracers such as horseradish peroxidase (HRP) or biotinylated dextran amine (BDA), but large percentages of efferent neurons were found to be double labeled when using two fluorescent substances including: fluorogold, microruby dextran amine, or rhodamine labeled latex beads. These data suggest a potential role for vestibular efferent neurons in modulating the dynamics of the vestibulo-ocular reflex (VOR) during normal and adaptive conditions.

  7. Callosal Disconnection Syndrome Associated with Relapsing Polychondritis.

    PubMed

    Baba, Toru; Kanno, Shigenori; Shijo, Tomomi; Nishio, Yoshiyuki; Iizuka, Osamu; Kamimura, Naoto; Ishii, Tomonori; Mori, Etsuro

    2016-01-01

    Relapsing polychondritis (RP) is a rare inflammatory disorder of the cartilagenous structures, and it sometimes involves the central nervous system. Encephalitis associated with RP causes a wide variety of symptoms according to the affected sites. We herein report the first case of 72-year-old right-handed man who developed acute meningoencephalitis associated with RP involving the corpus callous. After immunosuppressive therapy, his symptoms dramatically improved, but difficulty in performing bimanual movements with occasional diagonistic dyspraxia in his right hand remained. Because callosal signs are easily missed, especially in acute settings, it would be useful to know that RP can sometimes cause callosal disconnection syndrome.

  8. Efferent Insights into Cochlear Mechanics

    NASA Astrophysics Data System (ADS)

    Cooper, Nigel P.; Guinan, John J.

    2011-11-01

    Medial olivocochlear efferent (MOCE) effects on tone-evoked basilar membrane (BM) vibrations are analyzed in terms of the vector differences between BM responses with and without MOCE stimulation. The technique is sensitive to rapid (i.e., "fast", τ≤100 ms) changes in both the amplitude and the phase of the BM responses, and reveals MOCE effects over much wider frequency and intensity ranges (for a given BM location) than previously envisioned. The findings confirm and extend previous suggestions that MOCE effects are brought about by at least two different, outer-hair-cell based mechanisms. The effects on BM responses to characteristic frequency (CF) tones are consistent with suggestions that the MOCEs affect both the stiffness and the damping of the cochlear partition (damping effects dominating at low levels, and stiffness effects dominating at high levels). The analyses also indicate that MOCE activity can enhance, rather than inhibit, BM responses to low frequency tones (well below CF)—albeit by miniscule amounts. If one assumes that all of the mechanical effects of MOCE activation are brought about via gain changes in a single "cochlear amplifier" [4], these results seem to reveal that this amplifier exhibits a frequency-dependent transition from negative feedback (below CF) to positive feedback (near CF). This scenario is reminiscent of the type of amplification proposed by Mountain et al. a long, long time ago [9].

  9. Neuroimaging techniques offer new perspectives on callosal transfer and interhemispheric communication.

    PubMed

    Doron, Karl W; Gazzaniga, Michael S

    2008-09-01

    The brain relies on interhemispheric communication for coherent integration of cognition and behavior. Surgical disconnection of the two cerebral hemispheres has granted numerous insights into the functional organization of the corpus callosum (CC) and its relationship to hemispheric specialization. Today, technologies exist that allow us to examine the healthy, intact brain to explore the ways in which callosal organization relates to normal cognitive functioning and cerebral lateralization. The CC is organized in a topographical manner along its antero-posterior axis. Evidence from neuroimaging studies is revealing with greater specificity the function and the cortical projection targets of the topographically organized callosal subregions. The size, myelination and density of fibers in callosal subregions are related to function of the brain regions they connect: smaller fibers are slow-conducting and connect higher-order association areas; larger fibers are fast-conducting and connect visual, motor and secondary somotosensory areas. A decrease in fiber size and transcallosal connectivity might be related to a reduced need for interhemispheric communication due, in part, to increased intrahemispheric connectivity and specialization. Additionally, it has been suggested that lateralization of function seen in the human brain lies along an evolutionary continuum. Hemispheric specialization reduces duplication of function between the hemispheres. The microstructure and connectivity patterns of the CC provide a window for understanding the evolution of hemispheric asymmetries and lateralization of function. Here, we review the ways in which converging methodologies are advancing our understanding of interhemispheric communication in the normal human brain.

  10. Auditory Efferent System Modulates Mosquito Hearing.

    PubMed

    Andrés, Marta; Seifert, Marvin; Spalthoff, Christian; Warren, Ben; Weiss, Lukas; Giraldo, Diego; Winkler, Margret; Pauls, Stephanie; Göpfert, Martin C

    2016-08-01

    The performance of vertebrate ears is controlled by auditory efferents that originate in the brain and innervate the ear, synapsing onto hair cell somata and auditory afferent fibers [1-3]. Efferent activity can provide protection from noise and facilitate the detection and discrimination of sound by modulating mechanical amplification by hair cells and transmitter release as well as auditory afferent action potential firing [1-3]. Insect auditory organs are thought to lack efferent control [4-7], but when we inspected mosquito ears, we obtained evidence for its existence. Antibodies against synaptic proteins recognized rows of bouton-like puncta running along the dendrites and axons of mosquito auditory sensory neurons. Electron microscopy identified synaptic and non-synaptic sites of vesicle release, and some of the innervating fibers co-labeled with somata in the CNS. Octopamine, GABA, and serotonin were identified as efferent neurotransmitters or neuromodulators that affect auditory frequency tuning, mechanical amplification, and sound-evoked potentials. Mosquito brains thus modulate mosquito ears, extending the use of auditory efferent systems from vertebrates to invertebrates and adding new levels of complexity to mosquito sound detection and communication. PMID:27476597

  11. Medial Cochlear Efferent Function: A Theoretical Analysis

    NASA Astrophysics Data System (ADS)

    Mountain, David C.

    2011-11-01

    Since the discovery of the cochlear efferent system, many hypotheses have been put forth for its function. These hypotheses for its function range from protecting the cochlea from over stimulation to improving the detection of sounds in noise. It is known that the medial efferent system innervates the outer hair cells and that stimulation of this system reduces basilar membrane and auditory nerve sensitivity which suggests that this system acts to decrease the gain of the cochlear amplifier. Here I present modeling results as well as analysis of published experimental data that suggest that the function of the medial efferent reflex is to decrease the cochlear amplifier gain by just the right amount so that the nonlinearity in the basilar membrane response lines up perfectly with the inner hair cell nonlinear transduction process to produce a hair cell receptor potential that is proportional to the logarithm of the sound pressure level.

  12. Efferent pathways of the mouse lateral habenula

    PubMed Central

    Quina, Lely A.; Tempest, Lynne; Ng, Lydia; Harris, Julie; Ferguson, Susan; Jhou, Thomas; Turner, Eric E.

    2014-01-01

    The lateral habenula (LHb) is part of the habenula complex of the dorsal thalamus. Recent studies of the LHb have focused on its projections to the ventral tegmental area (VTA) and rostromedial tegmental nucleus (RMTg), which contain GABAergic neurons that mediate reward prediction error via inhibition of dopaminergic activity. However, older studies in the rat have also identified LHb outputs to the lateral and posterior hypothalamus, median raphe, dorsal raphe, and dorsal tegmentum. Although these studies have shown that the medial and lateral divisions of the LHb have somewhat distinct projections, the topographic specificity of LHb efferents is not completely understood, and the relative extent of these projections to brainstem targets is unknown. Here we have used anterograde tracing with adeno-associated virus mediated expression of green fluorescent protein, combined with serial two-photon tomography, to map the efferents of the LHb on a standard coordinate system for the entire mouse brain, and reconstruct the efferent pathways of the LHb in three dimensions. Using automated quantitation of fiber density, we show that in addition to the RMTg, the median raphe, caudal dorsal raphe, and pontine central gray are major recipients of LHb efferents. Using retrograde tract tracing with cholera toxin subunit B, we show that LHb neurons projecting to the hypothalamus, VTA, median raphe, and caudal dorsal raphe, and pontine central gray reside in characteristic, but sometimes overlapping regions of the LHb. Together these results provide the anatomical basis for systematic studies of LHb function in neural circuits and behavior in mice. PMID:25099741

  13. Efferent pathways of the mouse lateral habenula.

    PubMed

    Quina, Lely A; Tempest, Lynne; Ng, Lydia; Harris, Julie A; Ferguson, Susan; Jhou, Thomas C; Turner, Eric E

    2015-01-01

    The lateral habenula (LHb) is part of the habenula complex of the dorsal thalamus. Recent studies of the LHb have focused on its projections to the ventral tegmental area (VTA) and rostromedial tegmental nucleus (RMTg), which contain γ-aminobutyric acid (GABA)ergic neurons that mediate reward prediction error via inhibition of dopaminergic activity. However, older studies in the rat have also identified LHb outputs to the lateral and posterior hypothalamus, median raphe, dorsal raphe, and dorsal tegmentum. Although these studies have shown that the medial and lateral divisions of the LHb have somewhat distinct projections, the topographic specificity of LHb efferents is not completely understood, and the relative extent of these projections to brainstem targets is unknown. Here we have used anterograde tracing with adeno-associated virus-mediated expression of green fluorescent protein, combined with serial two-photon tomography, to map the efferents of the LHb on a standard coordinate system for the entire mouse brain, and reconstruct the efferent pathways of the LHb in three dimensions. Using automated quantitation of fiber density, we show that in addition to the RMTg, the median raphe, caudal dorsal raphe, and pontine central gray are major recipients of LHb efferents. By using retrograde tract tracing with cholera toxin subunit B, we show that LHb neurons projecting to the hypothalamus, VTA, median raphe, caudal dorsal raphe, and pontine central gray reside in characteristic, but sometimes overlapping regions of the LHb. Together these results provide the anatomical basis for systematic studies of LHb function in neural circuits and behavior in mice. J. Comp. Neurol. 523:32-60, 2015. © 2014 Wiley Periodicals, Inc. PMID:25099741

  14. Interhemispheric connections of the somatosensory cortex in the rabbit.

    PubMed

    Ledoux, M S; Whitworth, R H; Gould, H J

    1987-04-01

    Corpus callosal connections of somatosensory cortex were studied in rabbits by combining anatomical tracing and electrophysiological mapping in the same animals. The results show that callosal connections are unevenly distributed in SI and SII. In SI, the representations of all body surfaces caudal to the neck and midline structures of the head have dense callosal connections. Conversely, connections are sparse to absent within representations of laterally positioned surfaces of the head, such as the sinus hairs, vibrissae, and nonmidline portions of the lips. Almost all of SII has dense callosal connections; only the representations of the vibrissae and sinus hairs have moderate callosal connections. The laminar distribution of callosal connections in rabbit SI and SII is similar to that observed in other mammals. Callosal terminations extend from the inner portion of layer I to the outer portion of layer VI, are moderately denser in the supragranular layers, and are sparse in layer IV. Callosally projecting cells are found predominantly in layers II, III, and V and are sparse in layers IV and VI. These data further emphasize the direct correspondence between the pattern of callosal connections in SI and the functional importance of particular body surfaces. Hence, representations of body surfaces important in the exploration of the environment are relatively free of callosal connections, whereas representations of midline and more lateral surfaces, less significant in tactile exploration, receive dense callosal connections. Callosal connections in rabbits are distributed extensively throughout responsive koniocortical regions rather than being relegated to distinct, specialized regions of "unresponsive" dysgranular cortex as in rodents.

  15. Synthesis of a callosic substance during rhizoid differentiation in Spirogyra.

    PubMed

    Yamada, Shin-ya; Sonobe, Seiji; Shimmen, Teruo

    2003-11-01

    Spirogyra living in running water is anchored to the substratum by rhizoids that form at the ends of the filaments. A new terminal cell differentiates into a rhizoid cell if the filament is injured. The mode of growth changes from diffuse to tip growth when rhizoid differentiation begins. In this study, we found that a callosic substance was synthesized during rhizoid differentiation. Decreasing the cell turgor, lowering extracellular Ca2+ or adding Gd3+, all inhibited the commencement of rhizoid differentiation as well as synthesis of the callose-like substance at the tip of the terminal cell. A callosic substance was also synthesized during formation of the conjugation tube.

  16. Victorin-induced callose in mesophyll protoplasts of Avena sativa

    SciTech Connect

    Schaeffer, H.J.; Walton, J.D. )

    1991-05-01

    Callose ((1-3){beta}-D-glucan), measured as incorporation of {sup 14}C-glucose into ethanol-insoluble product, is produced within 2h in victorin treated mesophyll protoplasts of victorin-sensitive cultivars of oat (Avena sativa). This production is ten-fold higher in the presence of 6 ng victorin/ml than untreated protoplasts after 2h. Microsomes of victorin-treated and untreated protoplasts are assayed for callose synthase activity using radiolabeled substrate, UDP-glucose. Preliminary studies indicate that microsomes of victorin-treated protoplasts have up to four times more callose synthase activity than microsomes of untreated protoplasts. Therefore, stimulation of callose synthase by some means that survives microsome isolation, at least in part, may account for the effect of victorin.

  17. Efferent feedback can explain many hearing phenomena

    NASA Astrophysics Data System (ADS)

    Holmes, W. Harvey; Flax, Matthew R.

    2015-12-01

    The mixed mode cochlear amplifier (MMCA) model was presented at the last Mechanics of Hearing workshop [4]. The MMCA consists principally of a nonlinear feedback loop formed when an efferent-controlled outer hair cell (OHC) is combined with the cochlear mechanics and the rest of the relevant neurobiology. Essential elements of this model are efferent control of the OHC motility and a delay in the feedback to the OHC. The input to the MMCA is the passive travelling wave. In the MMCA amplification is localized where both the neural and tuned mechanical systems meet in the Organ of Corti (OoC). The simplest model based on this idea is a nonlinear delay line resonator (DLR), which is mathematically described by a nonlinear delay-differential equation (DDE). This model predicts possible Hopf bifurcations and exhibits its most interesting behaviour when operating near a bifurcation. This contribution presents some simulation results using the DLR model. These show that various observed hearing phenomena can be accounted for by this model, at least qualitatively, including compression effects, two-tone suppression and some forms of otoacoustic emissions (OAEs).

  18. GABAergic and Glutamatergic Efferents of the Mouse Ventral Tegmental Area

    PubMed Central

    Taylor, Seth R; Badurek, Sylvia; DiLeone, Ralph J; Nashmi, Raad; Minichiello, Liliana; Picciotto, Marina R

    2014-01-01

    The role of dopaminergic (DA) projections from the ventral tegmental area (VTA) in appetitive and rewarding behavior has been widely studied, but the VTA also has documented DA-independent functions. Several drugs of abuse, including nicotine, act on VTA GABAergic neurons, and most studies have focused on local inhibitory connections. Relatively little is known about VTA GABA projection neurons and their connections to brain sites outside the VTA. In this study, we employed viral-vector mediated cell-type specific anterograde tracing, classical retrograde tracing and immunohistochemistry to characterize VTA GABA efferents throughout the brain. We found that VTA GABA neurons project widely to forebrain and brainstem targets, including the ventral pallidum, lateral and magnocellular preoptic nuclei, lateral hypothalamus and lateral habenula. Minor projections also go to central amygdala, mediodorsal thalamus, dorsal raphe and deep mesencephalic nuclei, and sparse projections go to prefrontal cortical regions and to nucleus accumbens shell and core. Importantly, these projections differ from the major VTA DA target regions. Retrograde tracing studies confirmed results from the anterograde experiments and differences in projections from VTA subnuclei. Retrogradely-labeled GABA neurons were not numerous and most non-TH/retrogradely labeled cells lacked GABAergic markers. Many non-DA/retrogradely labeled cells projecting to several areas express VGluT2. VTA GABA and glutamate neurons project throughout the brain, most prominently to regions with reciprocal connections to the VTA. These data indicate that VTA GABA and glutamate neurons may have more dopamine-independent functions than previously recognized. PMID:24715505

  19. Distribution and structure of efferent synapses in the chicken retina.

    PubMed

    Lindstrom, S H; Nacsa, N; Blankenship, T; Fitzgerald, P G; Weller, C; Vaney, D I; Wilson, Martin

    2009-01-01

    The visual system of birds includes an efferent projection from a visual area, the isthmo-optic nucleus in the midbrain, back to the retina. Using a combination of anterograde labeling of efferent fibers, reconstruction of dye-filled neurons, NADPH-diaphorase staining, and transmission electron microscopy, we have examined the distribution of efferent fibers and their synaptic structures in the chicken retina. We show that efferent fibers terminate strictly within the ventral retina. In two completely mapped retinas, only 2 fibers from a total of 15,359 terminated in the dorsal retina. The major synapse made by each efferent fiber is with a single efferent target amacrine cell (TC). This synapse consists of 5-25 boutons of 2 microm diameter, each with multiple active zones, pressed into the TC soma or synapsing with a basketwork of rudimentary TC dendrites in the inner nuclear layer (INL). This basketwork, which is sheathed by Muller cell processes, defines a private neuropil in the INL within which TCs were also seen to receive input from retinal neurons. In addition to the major synapse, efferent fibers typically produce several very thin processes that terminate nearby in single small boutons and for which the soma of a local amacrine cell is one of the likely postsynaptic partners. A minority of efferent fibers also give rise to a thicker process, terminating in a strongly diaphorase-positive ball about 5 microm in diameter.

  20. Callosal axon arbors in the limb representations of the somatosensory cortex (SI) in the agouti (Dasyprocta primnolopha).

    PubMed

    Rocha, E G; Santiago, L F; Freire, M A M; Gomes-Leal, W; Dias, I A; Lent, R; Houzel, J C; Franca, J G; Pereira, A; Picanço-Diniz, C W

    2007-01-10

    The present report compares the morphology of callosal axon arbors projecting from and to the hind- or forelimb representations in the primary somatosensory cortex (SI) of the agouti (Dasyprocta primnolopha), a large, lisencephlic Brazilian rodent that uses forelimb coordination for feeding. Callosal axons were labeled after single pressure (n = 6) or iontophoretic injections (n = 2) of the neuronal tracer biotinylated dextran amine (BDA, 10 kD), either into the hind- (n = 4) or forelimb (n = 4) representations of SI, as identified by electrophysiological recording. Sixty-nine labeled axon fragments located across all layers of contralateral SI representations of the hindlimb (n = 35) and forelimb (n = 34) were analyzed. Quantitative morphometric features such as densities of branching points and boutons, segments length, branching angles, and terminal field areas were measured. Cluster analysis of these values revealed the existence of two types of axon terminals: Type I (46.4%), less branched and more widespread, and Type II (53.6%), more branched and compact. Both axon types were asymmetrically distributed; Type I axonal fragments being more frequent in hindlimb (71.9%) vs. forelimb (28.13%) representation, while most of Type II axonal arbors were found in the forelimb representation (67.56%). We concluded that the sets of callosal axon connecting fore- and hindlimb regions in SI are morphometrically distinct from each other. As callosal projections in somatosensory and motor cortices seem to be essential for bimanual interaction, we suggest that the morphological specialization of callosal axons in SI of the agouti may be correlated with this particular function.

  1. Callose homeostasis at plasmodesmata: molecular regulators and developmental relevance

    PubMed Central

    De Storme, Nico; Geelen, Danny

    2014-01-01

    Plasmodesmata are membrane-lined channels that are located in the plant cell wall and that physically interconnect the cytoplasm and the endoplasmic reticulum (ER) of adjacent cells. Operating as controllable gates, plasmodesmata regulate the symplastic trafficking of micro- and macromolecules, such as endogenous proteins [transcription factors (TFs)] and RNA-based signals (mRNA, siRNA, etc.), hence mediating direct cell-to-cell communication and long distance signaling. Besides this physiological role, plasmodesmata also form gateways through which viral genomes can pass, largely facilitating the pernicious spread of viral infections. Plasmodesmatal trafficking is either passive (e.g., diffusion) or active and responses both to developmental and environmental stimuli. In general, plasmodesmatal conductivity is regulated by the controlled build-up of callose at the plasmodesmatal neck, largely mediated by the antagonistic action of callose synthases (CalSs) and β-1,3-glucanases. Here, in this theory and hypothesis paper, we outline the importance of callose metabolism in PD SEL control, and highlight the main molecular factors involved. In addition, we also review other proteins that regulate symplastic PD transport, both in a developmental and stress-responsive framework, and discuss on their putative role in the modulation of PD callose turn-over. Finally, we hypothesize on the role of structural sterols in the regulation of (PD) callose deposition and outline putative mechanisms by which this regulation may occur. PMID:24795733

  2. Callosally projecting neurons in the macaque monkey V1/V2 border are enriched in nonphosphorylated neurofilament protein

    NASA Technical Reports Server (NTRS)

    Hof, P. R.; Ungerleider, L. G.; Adams, M. M.; Webster, M. J.; Gattass, R.; Blumberg, D. M.; Morrison, J. H.; Bloom, F. E. (Principal Investigator)

    1997-01-01

    Previous immunohistochemical studies combined with retrograde tracing in macaque monkeys have demonstrated that corticocortical projections can be differentiated by their content of neurofilament protein. The present study analyzed the distribution of nonphosphorylated neurofilament protein in callosally projecting neurons located at the V1/V2 border. All of the retrogradely labeled neurons were located in layer III at the V1/V2 border and at an immediately adjacent zone of area V2. A quantitative analysis showed that the vast majority (almost 95%) of these interhemispheric projection neurons contain neurofilament protein immunoreactivity. This observation differs from data obtained in other sets of callosal connections, including homotypical interhemispheric projections in the prefrontal, temporal, and parietal association cortices, that were found to contain uniformly low proportions of neurofilament protein-immunoreactive neurons. Comparably, highly variable proportions of neurofilament protein-containing neurons have been reported in intrahemispheric corticocortical pathways, including feedforward and feedback visual connections. These results indicate that neurofilament protein is a prominent neurochemical feature that identifies a particular population of interhemispheric projection neurons at the V1/V2 border and suggest that this biochemical attribute may be critical for the function of this subset of callosal neurons.

  3. Visual speech gestures modulate efferent auditory system.

    PubMed

    Namasivayam, Aravind Kumar; Wong, Wing Yiu Stephanie; Sharma, Dinaay; van Lieshout, Pascal

    2015-03-01

    Visual and auditory systems interact at both cortical and subcortical levels. Studies suggest a highly context-specific cross-modal modulation of the auditory system by the visual system. The present study builds on this work by sampling data from 17 young healthy adults to test whether visual speech stimuli evoke different responses in the auditory efferent system compared to visual non-speech stimuli. The descending cortical influences on medial olivocochlear (MOC) activity were indirectly assessed by examining the effects of contralateral suppression of transient-evoked otoacoustic emissions (TEOAEs) at 1, 2, 3 and 4 kHz under three conditions: (a) in the absence of any contralateral noise (Baseline), (b) contralateral noise + observing facial speech gestures related to productions of vowels /a/ and /u/ and (c) contralateral noise + observing facial non-speech gestures related to smiling and frowning. The results are based on 7 individuals whose data met strict recording criteria and indicated a significant difference in TEOAE suppression between observing speech gestures relative to the non-speech gestures, but only at the 1 kHz frequency. These results suggest that observing a speech gesture compared to a non-speech gesture may trigger a difference in MOC activity, possibly to enhance peripheral neural encoding. If such findings can be reproduced in future research, sensory perception models and theories positing the downstream convergence of unisensory streams of information in the cortex may need to be revised.

  4. Agnosia, apraxia, callosal disconnection and other specific cognitive disorders.

    PubMed

    Acciarresi, Monica

    2012-01-01

    Cortical function deficits have long been studied by anatomoclinic correlations. Recent functional imaging studies have allowed scientists to better understand which cerebral areas and which networks are involved in cognitive function deficit. This chapter will review the current knowledge on agnosia, apraxia and callosal disconnection syndromes.

  5. On the mechanism of callose synthesis induction by metal ions in onion epidermal cells.

    PubMed

    Kartusch, R

    2003-03-01

    Metal ions induce the synthesis of callose in Allium cepa epidermal cells. Callose is deposited as single knoblike local accumulations, aggregates of knobs, or furrowed clusters tightly attached to the cell wall. The most effective metal is copper, it induces callose formation at micromolar concentrations. Agents acting on inositolphosphate metabolism, phospholipase inhibitors, calcium channel inhibitors, modulators of cytoplasmic calcium, or receptor antagonists influence callose synthesis. It is concluded that metal ions, especially Cu(2+), initiate a signal transduction chain by activation of phospholipases and generation of inositol 1,4,5-trisphosphate, and that callose synthesis is a cellular defence reaction caused by the disturbance of intracellular calcium homeostasis. PMID:12664286

  6. Deposition of callose in young ovules of two Taraxacum species varying in the mode of reproduction.

    PubMed

    Musiał, Krystyna; Kościńska-Pająk, Maria; Antolec, Renata; Joachimiak, Andrzej J

    2015-01-01

    Although callose occurs during megasporogenesis in most flowering plants, the knowledge about its general function and the mechanisms by which the callose layer is formed in particular places is still not sufficient. The results of previous studies suggest a total lack of callose in the ovules of diplosporous plants in which meiosis is omitted or disturbed. This report is the first documentation of callose events in dandelions ovules. We demonstrated the pattern of callose deposition during the formation of megaspores through diplospory of Taraxacum type and during normal meiotic megasporogenesis in apomictic triploid Taraxacum atricapillum and amphimictic diploid Taraxacum linearisquameum. We found the presence of callose in the megasporocyte wall of both diplosporous and sexual dandelions. However, in a diplosporous dandelion, callose predominated at the micropylar pole of megaspore mother cell (MMC) which may be correlated with abnormal asynaptic meiosis and may indicate diplospory of the Taraxacum type. After meiotic division, callose is mainly deposited in the walls between megaspores in tetrads and in diplodyads. In subsequent stages, callose gradually disappears around the chalazal functional megaspore. However, some variations in the pattern of callose deposition within tetrad may reflect variable positioning of the functional megaspore (FM) observed in the ovules of T. linearisquameum. PMID:24938673

  7. Deposition of callose in young ovules of two Taraxacum species varying in the mode of reproduction.

    PubMed

    Musiał, Krystyna; Kościńska-Pająk, Maria; Antolec, Renata; Joachimiak, Andrzej J

    2015-01-01

    Although callose occurs during megasporogenesis in most flowering plants, the knowledge about its general function and the mechanisms by which the callose layer is formed in particular places is still not sufficient. The results of previous studies suggest a total lack of callose in the ovules of diplosporous plants in which meiosis is omitted or disturbed. This report is the first documentation of callose events in dandelions ovules. We demonstrated the pattern of callose deposition during the formation of megaspores through diplospory of Taraxacum type and during normal meiotic megasporogenesis in apomictic triploid Taraxacum atricapillum and amphimictic diploid Taraxacum linearisquameum. We found the presence of callose in the megasporocyte wall of both diplosporous and sexual dandelions. However, in a diplosporous dandelion, callose predominated at the micropylar pole of megaspore mother cell (MMC) which may be correlated with abnormal asynaptic meiosis and may indicate diplospory of the Taraxacum type. After meiotic division, callose is mainly deposited in the walls between megaspores in tetrads and in diplodyads. In subsequent stages, callose gradually disappears around the chalazal functional megaspore. However, some variations in the pattern of callose deposition within tetrad may reflect variable positioning of the functional megaspore (FM) observed in the ovules of T. linearisquameum.

  8. Fetal development of the corpus callosum: Insights from a 3T DTI and tractography study in a patient with segmental callosal agenesis.

    PubMed

    Scola, Elisa; Sirgiovanni, Ida; Avignone, Sabrina; Cinnante, Claudia Maria; Biffi, Riccardo; Fumagalli, Monica; Triulzi, Fabio

    2016-10-01

    Commissural embryology mechanisms are not yet completely understood. The study and comprehension of callosal dysgenesis can provide remarkable insights into embryonic or fetal commissural development. The diffusion tensor imaging (DTI) technique allows the in vivo analyses of the white-matter microstructure and is a valid tool to clarify the disturbances of brain connections in patients with dysgenesis of the corpus callosum (CC). The segmental callosal agenesis (SCAG) is a rare partial agenesis of the corpus callosum (ACC). In a newborn with SCAG the DTI and tractography analyses proved that the CC was made of two separate segments consisting respectively of the ventral part in the genu and body of the CC, connecting the frontal lobes, and the dorsal part in the CC splenium and the attached hippocampal commissure (HC), connecting the parietal lobes and the fornix. These findings support the embryological thesis of a separated origin of the ventral and the dorsal parts of the CC.

  9. Fetal development of the corpus callosum: Insights from a 3T DTI and tractography study in a patient with segmental callosal agenesis.

    PubMed

    Scola, Elisa; Sirgiovanni, Ida; Avignone, Sabrina; Cinnante, Claudia Maria; Biffi, Riccardo; Fumagalli, Monica; Triulzi, Fabio

    2016-10-01

    Commissural embryology mechanisms are not yet completely understood. The study and comprehension of callosal dysgenesis can provide remarkable insights into embryonic or fetal commissural development. The diffusion tensor imaging (DTI) technique allows the in vivo analyses of the white-matter microstructure and is a valid tool to clarify the disturbances of brain connections in patients with dysgenesis of the corpus callosum (CC). The segmental callosal agenesis (SCAG) is a rare partial agenesis of the corpus callosum (ACC). In a newborn with SCAG the DTI and tractography analyses proved that the CC was made of two separate segments consisting respectively of the ventral part in the genu and body of the CC, connecting the frontal lobes, and the dorsal part in the CC splenium and the attached hippocampal commissure (HC), connecting the parietal lobes and the fornix. These findings support the embryological thesis of a separated origin of the ventral and the dorsal parts of the CC. PMID:27549148

  10. Efferent Modulation of Stimulus Frequency Otoacoustic Emission Fine Structure

    PubMed Central

    Zhao, Wei; Dewey, James B.; Boothalingam, Sriram; Dhar, Sumitrajit

    2015-01-01

    Otoacoustic emissions, sounds generated in the inner ear, have become a convenient non-invasive tool to examine the efferent modulation of cochlear mechanics. Activation of the medial olivocochlear (MOC) efferents has been shown to alter the magnitude of these emissions. When the effects of efferent activation on the detailed spectral structures of these emissions have been examined, a shift of the spectral patterns toward higher frequencies has been reported for distortion product and spontaneous otoacoustic emissions. Stimulus frequency otoacoustic emissions (SFOAEs) have been proposed as the preferred emission type in the study of efferent modulation due to the simplicity of their production leading to the possibility of clearer interpretation of results. The effects of efferent activation on the complex spectral patterns of SFOAEs have not been examined to the best of our knowledge. We have examined the effects of activating the MOC efferents using broadband noise in normal-hearing humans. The detailed spectral structure of SFOAEs, known as fine structure, was recorded with and without contralateral acoustic stimulation. Results indicate that SFOAEs are reduced in magnitude and their fine structure pushed to higher frequencies by contralateral acoustic stimulation. These changes are similar to those observed in distortion product or spontaneous otoacoustic emissions and behavioral hearing thresholds. Taken together with observations made about magnitude and phase changes in otoacoustic emissions and hearing thresholds upon contralateral acoustic stimulation, all changes in otoacoustic emission and hearing threshold fine structure appear to be driven by a common set of mechanisms. Specifically, frequency shifts in fine structure patterns appear to be linked to changes in SFOAE phase due to contralateral acoustic stimulation. PMID:26696843

  11. Efferent system in the retina of the frog, Rana catesbiana.

    PubMed

    Tasaki, K; Tsukahara, Y; Watanabe, M

    1978-12-01

    Single units were recorded through glass microelectrodes placed on the optic disk or on the retina of the opened eye of the frog (Rana catesbiana). Units were classified as A-, B-, and C-fibers according to conduction velocities. By the method of collision between naturally elicited and electrically elicited impulses, many of the B-fibers and some A- and C-fibers, which showed unusual behavior to photic stimulation, were found to be efferent fibers. Retinal effects of the efferent nerves were studied by repetitive stimulation and cooling of the optic nerve. The effects were found to be both inhibitory and excitatory. PMID:314669

  12. A Specific Role for Efferent Information in Self-Recognition

    ERIC Educational Resources Information Center

    Tsakiris, M.; Haggard, P.; Franck, N.; Mainy, N.; Sirigu, A.

    2005-01-01

    We investigated the specific contribution of efferent information in a self-recognition task. Subjects experienced a passive extension of the right index finger, either as an effect of moving their left hand via a lever ('self-generated action'), or imposed externally by the experimenter ('externally-generated action'). The visual feedback was…

  13. Efferent projections of the ectostriatum in the pigeon (Columba livia)

    NASA Technical Reports Server (NTRS)

    Husband, S. A.; Shimizu, T.

    1999-01-01

    The ectostriatum is a major visual component of the avian telencephalon. The core region of the ectostriatum (Ec) receives visual input from the optic tectum through thalamic nuclei. In the present study, the efferent projections of the ectostriatum were investigated by using the anterograde tracers Phaseolus vulgaris leucoagglutinin and biotinylated dextran amine. Projection patterns resulting from these tracers were confirmed by the retrograde tracer cholera toxin subunit B. When anterograde tracers were injected in Ec, primary projections were seen traveling dorsolaterally to the belt region of the ectostriatum (Ep) and the neostriatal area immediately surrounding Ep (Ep2). Neurons in Ep sent projections primarily to the overlying Ep2. The efferents of Ep2 traveled dorsolaterally to terminate in three telencephalic regions, from anterior to posterior: (1) neostriatum frontale, pars lateralis (NFL), (2) area temporo-parieto-occipitalis (TPO), and (3) neostriatum intermedium, pars lateralis (NIL). A part of the archistriatum intermedium and the lateral part of the neostriatum caudale also received somewhat minor projections. In addition, some neurons in Ec were also the source of direct, but minor, projections to the NFL, TPO, NIL, and archistriatum intermedium. The topographical relationship among the primary (Ec), secondary (Ep and Ep2), and tertiary (NFL, TPO, NIL) areas indicate that the neural populations for visual processing are organized along the rostral-caudal axis. Thus, the anterior Ec sent efferents to the anterior Ep, which in turn sent projections to anterior Ep2. Neurons in the anterior Ep2 sent projections to NFL and the anterior TPO. Similarly, the intermediate and posterior Ec sent projections to corresponding parts of Ep, whose efferents projected to intermediate and posterior Ep2, respectively. The intermediate Ep2 gave rise to major projections to TPO, whereas posterior Ep2 neurons sent efferents primarily to NIL. The organization of this

  14. The relationship of callosal anatomy to paw preference in dogs.

    PubMed

    Aydinlioglu, A A; Arslanirli, K A; Riza Erdogan, M A; Ragbetli, M C; Keleş, P; Diyarbakirli, S

    2000-04-01

    Previous studies have described the paw preference and asymmetry in dog brains, based on experimental studies. The purpose of the present study is to investigate a possible association between callosal anatomy and paw preference in dogs. The midsagittal area of the dog corpus callosum was measured in its entirety and in six subdivisions in a sample of 21 brains obtained from 9 male and 12 female mongrel dogs which had paw preference testing. The present study showed significant paw differences in dog corpus callosum. A posterior segment of the callosum, the isthmus, was significantly larger in the right pawedness than the left.

  15. Diffusion Weighted Callosal Integrity Reflects Interhemispheric Communication Efficiency in Multiple Sclerosis

    ERIC Educational Resources Information Center

    Warlop, Nele P.; Achten, Eric; Debruyne, Jan; Vingerhoets, Guy

    2008-01-01

    We aimed to investigate the relation between damage in the corpus callosum and the performance on an interhemispheric communication task in patients with multiple sclerosis (MS). Relative callosal lesion load defined as the ratio between callosal area and the total lesion load in the total corpus callosum, and the diffusion tensor imaging (DTI)…

  16. Bilateral redundancy gain and callosal integrity in a man with callosal lipoma: a diffusion-tensor imaging study.

    PubMed

    Roser, Matthew E; Corballis, Michael C; Jansari, Ashok; Fulford, Jon; Benattayallah, Abdelmalek; Adams, William M

    2012-06-01

    We investigated whether abnormalities in the structural organization of the corpus callosum in the presence of curvilinear lipoma are associated with increased facilitation of response time to bilateral stimuli, an effect known as the redundancy gain (RG). A patient (A.J.) with a curvilinear lipoma of the corpus callosum, his genetically-identical twin, and age-matched control participants made speeded responses to luminant stimuli. Structural organization of callosal regions was assessed with diffusion-tensor imaging. A.J. was found to have reduced structural integrity in the splenium of the corpus callosum and produced a large RG suggestive of neural summation. PMID:21787244

  17. Responses of efferent octopaminergic thoracic unpaired median neurons in the locust to visual and mechanosensory signals.

    PubMed

    Field, Laurence H; Duch, Carsten; Pflüger, Hans-Joachim

    2008-01-01

    Insect thoracic ganglia contain efferent octopaminergic unpaired median neurons (UM neurons) located in the midline, projecting bilaterally and modulating neuromuscular transmission, muscle contraction kinetics, sensory sensitivity and muscle metabolism. In locusts, these neurons are located dorsally or ventrally (DUM- or VUM-neurons) and divided into functionally different sub-populations activated during different motor tasks. This study addresses the responsiveness of locust thoracic DUM neurons to various sensory stimuli. Two classes of sense organs, cuticular exteroreceptor mechanosensilla (tactile hairs and campaniform sensilla), and photoreceptors (compound eyes and ocelli) elicited excitatory reflex responses. Chordotonal organ joint receptors caused no responses. The tympanal organ (Müller's organ) elicited weak excitatory responses most likely via generally increased network activity due to increased arousal. Vibratory stimuli to the hind leg subgenual organ never elicited responses. Whereas DUM neurons innervating wing muscles are not very responsive to sensory stimulation, those innervating leg and other muscles are very responsive to stimulation of exteroreceptors and hardly responsive to stimulation of proprioceptors. After cutting both cervical connectives all mechanosensory excitation is lost, even for sensory inputs from the abdomen. This suggests that, in contrast to motor neurons, the sensory inputs to octopaminergic efferent neuromodulatory cells are pre-processed in the suboesophageal ganglion. PMID:18021797

  18. Callosal lesions and behavior: history and modern concepts.

    PubMed

    Devinsky, Orrin; Laff, Rachel

    2003-12-01

    Callosotomy has played a unique role in the treatment of epilepsy and in the understanding of human brain function. The pioneering work of Dejerine and Liepmann presenting the first findings of callosal lesion pathology at the turn of the 20th century was accepted but then quickly forgotten. Two schools resurrected the phoenix of callosal syndromes: Roger Sperry and Michael Gazzaniga leading in experimental neuroscience, and Norman Geschwind leading in clinical neurology. Callosotomy remains an effective technique to treat atonic, tonic, and tonic-clonic seizures, especially in patients with symptomatic generalized epilepsies such as Lennox-Gastaut syndrome. Neurologic, cognitive, and behavioral complications limit its use given that precise characterization of these complications as well as their frequency is difficult. The high frequencies of developmental delays, severe seizures, head injuries, antiepileptic drug burden, and other factors limit the ability to attribute a specific change to surgical intervention, since surgery can change multiple factors. For example, subtle behavioral changes in executive function and personality are difficult to delineate in a population with preexisting neurologic and psychiatric disorders. Despite this, a clearer picture of the effects of callosotomy, as defined by clinical neurology and neuropsychology as well as cognitive neuroscience, is emerging. PMID:14698693

  19. Callosal apraxia: a 34-year follow-up study.

    PubMed

    Falchook, Adam D; Watson, Robert T; Heilman, Kenneth M

    2016-06-01

    Loss of ability of the left upper limb (LUL) to correctly produce spatial and temporal components of skilled purposeful movements was reported 34 years ago in a woman with a callosal infarction. To learn about recovery, we recently reexamined this woman. This woman was tested for ideomotor apraxia by asking her to pantomime to command and to seeing pictures of tools. Whereas she performed normally with her right upper limb, her LUL remained severely apraxic, making many spatial (postural and movement) errors. Initially, she did not reveal loss of finger-hand deftness (limb-kinetic apraxia), and when tested again with the coin rotation task, her left hand performance was normal. Without vision, she could name objects placed in her left hand but not name numbers written in this hand. Since this woman had a callosal lesion, failure to recover cannot be accounted for by left hemisphere inhibition of her right hemisphere. Although failure for her LUL to improve may have been related to not using her LUL for skilled actions, her right hemisphere was able to observe transitive actions, and this failure of her LUL to produce skilled purposeful movements suggests her right hemisphere may have not had the capacity to learn these movement representations. Without vision, her ability to recognize objects with her left hand, but not numbers written on her left palm, suggests graphesthesia may require that her left hand did not have access to movement representations important for programming these numbers when writing.

  20. Callosal apraxia: a 34-year follow-up study.

    PubMed

    Falchook, Adam D; Watson, Robert T; Heilman, Kenneth M

    2016-06-01

    Loss of ability of the left upper limb (LUL) to correctly produce spatial and temporal components of skilled purposeful movements was reported 34 years ago in a woman with a callosal infarction. To learn about recovery, we recently reexamined this woman. This woman was tested for ideomotor apraxia by asking her to pantomime to command and to seeing pictures of tools. Whereas she performed normally with her right upper limb, her LUL remained severely apraxic, making many spatial (postural and movement) errors. Initially, she did not reveal loss of finger-hand deftness (limb-kinetic apraxia), and when tested again with the coin rotation task, her left hand performance was normal. Without vision, she could name objects placed in her left hand but not name numbers written in this hand. Since this woman had a callosal lesion, failure to recover cannot be accounted for by left hemisphere inhibition of her right hemisphere. Although failure for her LUL to improve may have been related to not using her LUL for skilled actions, her right hemisphere was able to observe transitive actions, and this failure of her LUL to produce skilled purposeful movements suggests her right hemisphere may have not had the capacity to learn these movement representations. Without vision, her ability to recognize objects with her left hand, but not numbers written on her left palm, suggests graphesthesia may require that her left hand did not have access to movement representations important for programming these numbers when writing. PMID:26928117

  1. Callosal lesions and behavior: history and modern concepts.

    PubMed

    Devinsky, Orrin; Laff, Rachel

    2003-12-01

    Callosotomy has played a unique role in the treatment of epilepsy and in the understanding of human brain function. The pioneering work of Dejerine and Liepmann presenting the first findings of callosal lesion pathology at the turn of the 20th century was accepted but then quickly forgotten. Two schools resurrected the phoenix of callosal syndromes: Roger Sperry and Michael Gazzaniga leading in experimental neuroscience, and Norman Geschwind leading in clinical neurology. Callosotomy remains an effective technique to treat atonic, tonic, and tonic-clonic seizures, especially in patients with symptomatic generalized epilepsies such as Lennox-Gastaut syndrome. Neurologic, cognitive, and behavioral complications limit its use given that precise characterization of these complications as well as their frequency is difficult. The high frequencies of developmental delays, severe seizures, head injuries, antiepileptic drug burden, and other factors limit the ability to attribute a specific change to surgical intervention, since surgery can change multiple factors. For example, subtle behavioral changes in executive function and personality are difficult to delineate in a population with preexisting neurologic and psychiatric disorders. Despite this, a clearer picture of the effects of callosotomy, as defined by clinical neurology and neuropsychology as well as cognitive neuroscience, is emerging.

  2. Stimulation of callose synthesis in vivio correlates with changes in intracellular distribution of the callose synthase activator [beta]-Furfuryl-[beta]-Glucoside

    SciTech Connect

    Ohana, P.; Benziman, M.; Delmer, D.P. )

    1993-01-01

    [beta]-Furfuryl-[beta]-glucoside (FG) has been shown to be a specific endogenous activator of higher plant callose synthase. Because glycosides such as FG are usually sequestered in vacuoles, we have proposed that activation of callose synthesis in vivo may involve a change in the compartmentation on FG and Ca[sup 2+], resulting in a synergistic activation of callose synthase. The use of suspension-cultured barley (Hordeum bulbosum L.) cells provides evidence that FG is largely sequestered in the vacuole. Furthermore, conditions that lead to induction of callose synthesis in vivo correspondingly lead to elevation of the cytoplasmic concentration of FG. These conditions include the lowering of cytoplasmic pH or elevation of cytoplasmic Ca[sup 2+]. Oligogalacturonide elicitors have also been reported to cause similar changes in cytoplasmic pH and Ca[sup 2+] concentration, and such an elicitor also causes and elevation in cytoplasmic FG coupled with stimulation of callose synthesis. These results support the concept that a relative redistribution of FG between cytoplasm and vacuole may be one of the components of the signal transduction pathway for elicitation of callose synthase in vivo. 18 refs., 1 fig., 2 tabs.

  3. Modulation of Auditory Signal-to-Noise Ratios by Efferent Stimulation

    PubMed Central

    Tomchik, Seth M.; Lu, Zhongmin

    2006-01-01

    One of the primary challenges that sensory systems face is extracting relevant information from background noise. In the auditory system, the ear receives efferent feedback, which may help it extract signals from noise. Here we directly test the hypothesis that efferent activity increases the signal-to-noise ratio (SNR) of the ear, using the relatively simple teleost ear. Tone-evoked saccular potentials were recorded before and after efferent stimulation, and the SNR of the responses was calculated. In quiet conditions, efferent stimulation suppressed saccular responses to a tone, reducing the SNR. However, when masking noise was added, efferent stimulation increased the SNR of the saccular responses within a range of stimulus combinations. These data demonstrate that auditory efferent feedback can increase SNR in conditions where a signal is masked by noise, thereby enhancing the encoding of signals in noise. Efferent feedback thus performs a fundamental signal processing function, helping the animal to hear sounds in difficult listening conditions. PMID:16554519

  4. Inhibitory neurotransmission regulates vagal efferent activity and gastric motility.

    PubMed

    McMenamin, Caitlin A; Travagli, R Alberto; Browning, Kirsteen N

    2016-06-01

    The gastrointestinal tract receives extrinsic innervation from both the sympathetic and parasympathetic nervous systems, which regulate and modulate the function of the intrinsic (enteric) nervous system. The stomach and upper gastrointestinal tract in particular are heavily influenced by the parasympathetic nervous system, supplied by the vagus nerve, and disruption of vagal sensory or motor functions results in disorganized motility patterns, disrupted receptive relaxation and accommodation, and delayed gastric emptying, amongst others. Studies from several laboratories have shown that the activity of vagal efferent motoneurons innervating the upper GI tract is inhibited tonically by GABAergic synaptic inputs from the adjacent nucleus tractus solitarius. Disruption of this influential central GABA input impacts vagal efferent output, hence gastric functions, significantly. The purpose of this review is to describe the development, physiology, and pathophysiology of this functionally dominant inhibitory synapse and its role in regulating vagally determined gastric functions. PMID:27302177

  5. Exploring local immune responses to vaccines using efferent lymphatic cannulation.

    PubMed

    Mahakapuge, Thilini An; Every, Alison L; Scheerlinck, Jean-Pierre Y

    2015-04-01

    The early stages of the induction of a primary immune response to a vaccine can shape the overall quality of the immune memory generated and hence affect the success of the vaccine. This early interaction between a vaccine and the immune system occurs first at the site of vaccination and can be explored using afferent cannulation. Subsequently, the vaccine and adjuvant activates the local draining lymph node. These interactions can be studied in real time in vivo using efferent lymphatic duct cannulation in large animal models and are the subject of this review. Depending on how the vaccine is delivered, the draining lymph nodes of different organs can be accessed, facilitating the testing of tissue-specific vaccinations. The efferent lymphatic cannulation model provides an avenue to study the effect of both adjuvants and antigen on the local immune system, and hence opens a pathway toward developing more effective ways of inducing immunity.

  6. Interhemispheric connections in the visual cortex of the squirrel monkey (Saimiri sciureus).

    PubMed

    Gould, H J; Weber, J T; Rieck, R W

    1987-02-01

    The callosal connections within the posterior parietal and occipital cortices were studied in the squirrel monkey with horseradish peroxidase tracing techniques. The data were evaluated with particular emphasis on the relationship of major callosal connections along the 17-18 border. The overall pattern of callosal connections in the squirrel monkey also was compared with callosal patterns in other New World simians. Our results show that the dense band of callosal connections along the 17-18 border in the squirrel monkey differs from the connections observed in other New World monkeys in that it is virtually confined to area 18 and avoids area 17. In addition to a continuous band of callosal connections in area 18 that parallels the 17-18 border, rostral extensions of the band are oriented perpendicular to the 17-18 border and present an obvious periodicity. The remaining parieto-occipital cortex contains a complex pattern of callosal connections that is strikingly similar to patterns reported for other New World monkeys. Thus, it is likely that the dorsolateral extrastriate visual cortex in the squirrel monkey is organized in a manner similar to that found within other New World monkeys.

  7. Callose deposition is required for somatic embryogenesis in plasmolyzed Eleutherococcus senticosus zygotic embryos.

    PubMed

    Tao, Lei; Yang, Yang; Wang, Qiuyu; You, Xiangling

    2012-10-31

    Dynamic changes in callose content, which is deposited as a plant defense response to physiological changes, were analyzed during somatic embryogenesis in Eleutherococcus senticosus zygotic embryos plasmolyzed in 1.0 M mannitol. During plasmolysis, callose deposition was clearly observed inside the plasma membrane of zygotic embryo epidermal cells using confocal laser scanning microscopy. The callose content of zygotic embryos gradually increased between 0 and 12 h plasmolysis and remained stable after 24 h plasmolysis. During eight weeks induction of somatic embryogenesis, the callose content of explants plasmolyzed for 12 h was slightly higher than explants plasmolyzed for 6 or 24 h, with the largest differences observed after 6 weeks culture, which coincided with the maximum callose content and highest number of globular somatic embryos. The highest frequency of somatic embryo formation was observed in explants plasmolyzed for 12 h. The somatic embryo induction rate and number of somatic embryos per explant were markedly different in zygotic embryos pretreated with plasmolysis alone (78.0%, 43 embryos per explant) and those pretreated with plasmolysis and the callose synthase inhibitor 2-deoxy-d-glucose (11.5%, 8 embryos per explant). This study indicates that callose production is required for somatic embryogenesis in plasmolyzed explants.

  8. Callose deposition is required for somatic embryogenesis in plasmolyzed Eleutherococcus senticosus zygotic embryos.

    PubMed

    Tao, Lei; Yang, Yang; Wang, Qiuyu; You, Xiangling

    2012-01-01

    Dynamic changes in callose content, which is deposited as a plant defense response to physiological changes, were analyzed during somatic embryogenesis in Eleutherococcus senticosus zygotic embryos plasmolyzed in 1.0 M mannitol. During plasmolysis, callose deposition was clearly observed inside the plasma membrane of zygotic embryo epidermal cells using confocal laser scanning microscopy. The callose content of zygotic embryos gradually increased between 0 and 12 h plasmolysis and remained stable after 24 h plasmolysis. During eight weeks induction of somatic embryogenesis, the callose content of explants plasmolyzed for 12 h was slightly higher than explants plasmolyzed for 6 or 24 h, with the largest differences observed after 6 weeks culture, which coincided with the maximum callose content and highest number of globular somatic embryos. The highest frequency of somatic embryo formation was observed in explants plasmolyzed for 12 h. The somatic embryo induction rate and number of somatic embryos per explant were markedly different in zygotic embryos pretreated with plasmolysis alone (78.0%, 43 embryos per explant) and those pretreated with plasmolysis and the callose synthase inhibitor 2-deoxy-d-glucose (11.5%, 8 embryos per explant). This study indicates that callose production is required for somatic embryogenesis in plasmolyzed explants. PMID:23203053

  9. Callose is integral to the development of permanent tetrads in the liverwort Sphaerocarpos.

    PubMed

    Renzaglia, Karen S; Lopez, Renee A; Johnson, Eric E

    2015-03-01

    A striking feature of the liverwort Sphaerocarpos is that pairs of male and female spores remain united in permanent tetrads. To identify the nature of this phenomenon and to test the hypothesis that callose is involved, we examined spore wall development in Sphaerocarpos miche lii, with emphasis on the appearance, location and fate of callose vis-à-vis construction of the sculptoderm. All stages of sporogenesis were examined using differential interference contrast optics, and aniline blue fluorescence to locate callose. For precise localization, specimens were immunogold labeled with anti-callose antibody and observed in the transmission electron microscope. Callose plays a role in Sphaerocarpos spore wall development not described in any other plant, including other liverworts. A massive callose matrix forms outside of the sculptured sporocyte plasmalemma that predicts spore wall ornamentation. Consequently, layers of exine form across adjacent spores uniting them. Spore wall development occurs entirely within the callose and involves the production of six layers of prolamellae that give rise to single or stacked tripartite lamellae (TPL). Between spores, an anastomosing network of exine layers forms in lieu of intersporal septum development. As sporopollenin assembles on TPL, callose progressively disappears from the inside outward leaving layers of sporopollenin impregnated exine, the sculptoderm, overlying a thick fibrillar intine. This developmental mechanism provides a direct pathway from callose deposition to sculptured exine that does not involve the intermediary primexine found in pollen wall development. The resulting tetrad, encased in a single wall, provides a simple model for development of permanent dyads and tetrads in the earliest fossil plants. PMID:25408505

  10. Callose is integral to the development of permanent tetrads in the liverwort Sphaerocarpos.

    PubMed

    Renzaglia, Karen S; Lopez, Renee A; Johnson, Eric E

    2015-03-01

    A striking feature of the liverwort Sphaerocarpos is that pairs of male and female spores remain united in permanent tetrads. To identify the nature of this phenomenon and to test the hypothesis that callose is involved, we examined spore wall development in Sphaerocarpos miche lii, with emphasis on the appearance, location and fate of callose vis-à-vis construction of the sculptoderm. All stages of sporogenesis were examined using differential interference contrast optics, and aniline blue fluorescence to locate callose. For precise localization, specimens were immunogold labeled with anti-callose antibody and observed in the transmission electron microscope. Callose plays a role in Sphaerocarpos spore wall development not described in any other plant, including other liverworts. A massive callose matrix forms outside of the sculptured sporocyte plasmalemma that predicts spore wall ornamentation. Consequently, layers of exine form across adjacent spores uniting them. Spore wall development occurs entirely within the callose and involves the production of six layers of prolamellae that give rise to single or stacked tripartite lamellae (TPL). Between spores, an anastomosing network of exine layers forms in lieu of intersporal septum development. As sporopollenin assembles on TPL, callose progressively disappears from the inside outward leaving layers of sporopollenin impregnated exine, the sculptoderm, overlying a thick fibrillar intine. This developmental mechanism provides a direct pathway from callose deposition to sculptured exine that does not involve the intermediary primexine found in pollen wall development. The resulting tetrad, encased in a single wall, provides a simple model for development of permanent dyads and tetrads in the earliest fossil plants.

  11. The area centralis in the chicken retina contains efferent target amacrine cells

    PubMed Central

    Weller, Cynthia; Lindstrom, Sarah H.; De Grip, Willem J.; Wilson, Martin

    2012-01-01

    The retinas of birds receive a substantial efferent, or centrifugal, input from a midbrain nucleus. The function of this input is presently unclear but previous work in the pigeon has shown that efferent input is excluded from the area centralis, suggesting that the functions of the area centralis and the efferent system are incompatible. Using an antibody specific to rods, we have identified the area centralis in another species, the chicken, and mapped the distribution of the unique amacrine cells that are the postsynaptic partners of efferent fibers. Efferent target amacrine cells are found within the chicken area centralis and their density is continuous across the border of the area centralis. In contrast to the pigeon retina then, we conclude that the chicken area centralis receives efferent input. We suggest that the difference between the 2 species is attributable to the presence of a fovea within the area centralis of the pigeon and its absence from that of the chicken. PMID:19296862

  12. A novel role of PR2 in abscisic acid (ABA) mediated, pathogen-induced callose deposition in Arabidopsis thaliana.

    PubMed

    Oide, Shinichi; Bejai, Sarosh; Staal, Jens; Guan, Na; Kaliff, Maria; Dixelius, Christina

    2013-12-01

    Pathogenesis-related protein 2 (PR2) is known to play a major role in plant defense and general stress responses. Resistance against the fungal pathogen Leptosphaeria maculans in Arabidopsis requires abscisic acid (ABA), which promotes the deposition of callose, a β-1,3-glucan polymer. Here, we examined the role of PR2 in callose deposition in relation to ABA treatment and challenge with L. maculans and Pseudomonas syringae. Characterization of PR2-overexpressing plants and the knockout line indicated that PR2 negatively affects callose deposition. Recombinant PR2 purified from Pichia pastoris showed callose-degrading activity, and a considerable reduction in the callose-degrading activity was observed in the leaf extract of the PR2 knockout line compared with the wild-type. ABA pretreatment before challenge with L. maculans concomitantly repressed PR2 and enhanced callose accumulation. Likewise, overexpression of an ABA biosynthesis gene NCED3 resulted in reduced PR2 expression and increased callose deposition. We propose that ABA promotes callose deposition through the transcriptional repression of PR2 in Arabidopsis challenged by L. maculans and P. syringae. Callose by itself is likely to act antagonistically on salicylic acid (SA) defense signaling, suggesting that PR2 may function as a modulator of callose- and SA-dependent defense responses.

  13. Clinical and topographical range of callosal infarction: a clinical and radiological correlation study.

    PubMed Central

    Giroud, M; Dumas, R

    1995-01-01

    A prospective clinical and radiological correlation study was performed to determine the frequency, and the clinical and radiological features of callosal infarction. From 1 January 1993 to the end of December 1993 282 cases of cerebral infarction seen in the Neurology service of the University Hospital of Dijon were studied prospectively. Eight cases with callosal ischaemic lesions were identified by CT and MRI. A callosal disconnection syndrome occurred in only five of eight patients, related to a single, large infarct or several infarctions in the anterior part of the corpus callosum. Clinical features were characterised by left ideomotor apraxia, construction apraxia, and left agraphia in all five cases. Alien hand was noted in only two cases. There were gait disorders in three cases with MRI features of multiple lacunes in a large part of the corpus callosum, and also the subcortical areas of both hemispheres. It is emphasised that callosal infarctions are not rare and that they contribute to the clinical features of strokes. As well as the classic incomplete callosal disconnection syndrome, these callosal ischaemic lesions may induce non-specific gait disorders. Images PMID:7673948

  14. SNAREs controlling vesicular release of BDNF and development of callosal axons

    PubMed Central

    Shimojo, Masafumi; Courchet, Julien; Pieraut, Simon; Torabi-Rander, Nina; Sando, Richard; Polleux, Franck; Maximov, Anton

    2015-01-01

    SUMMARY At presynaptic active zones, exocytosis of neurotransmitter vesicles (SVs) is driven by SNARE complexes that recruit Syb2 and SNAP25. However, it remains unknown which SNAREs promote the secretion of neuronal proteins, including those essential for circuit development and experience-dependent plasticity. Here, we demonstrate that Syb2 and SNAP25 mediate the vesicular release of BDNF in axons and dendrites of cortical neurons, suggesting these SNAREs act in multiple spatially-segregated secretory pathways. Remarkably, axonal secretion of BDNF is also strongly regulated by SNAP47 which interacts with SNAP25 but appears to be dispensable for exocytosis of SVs. Cell-autonomous ablation of SNAP47 disrupts the layer-specific branching of callosal axons of projection cortical neurons in vivo, and this phenotype is recapitulated by ablation of BDNF or its receptor, TrkB. Our results provide insights into the molecular mechanisms of protein secretion and define the functions of SNAREs in BDNF signaling and regulation of neuronal connectivity. PMID:25959820

  15. Efferent innervation of turtle semicircular canal cristae: comparisons with bird and mouse.

    PubMed

    Jordan, Paivi M; Fettis, Margaret; Holt, Joseph C

    2015-06-01

    In the vestibular periphery of nearly every vertebrate, cholinergic vestibular efferent neurons give rise to numerous presynaptic varicosities that target hair cells and afferent processes in the sensory neuroepithelium. Although pharmacological studies have described the postsynaptic actions of vestibular efferent stimulation in several species, characterization of efferent innervation patterns and the relative distribution of efferent varicosities among hair cells and afferents are also integral to understanding how efferent synapses operate. Vestibular efferent markers, however, have not been well characterized in the turtle, one of the animal models used by our laboratory. Here we sought to identify reliable efferent neuronal markers in the vestibular periphery of turtle, to use these markers to understand how efferent synapses are organized, and to compare efferent neuronal labeling patterns in turtle with two other amniotes using some of the same markers. Efferent fibers and varicosities were visualized in the semicircular canal of red-eared turtles (Trachemys scripta elegans), zebra finches (Taeniopygia guttata), and mice (Mus musculus) utilizing fluorescent immunohistochemistry with antibodies against choline acetyltransferase (ChAT). Vestibular hair cells and afferents were counterstained using antibodies to myosin VIIa and calretinin. In all species, ChAT labeled a population of small diameter fibers giving rise to numerous spherical varicosities abutting type II hair cells and afferent processes. That these ChAT-positive varicosities represent presynaptic release sites were demonstrated by colabeling with antibodies against the synaptic vesicle proteins synapsin I, SV2, or syntaxin and the neuropeptide calcitonin gene-related peptide. Comparisons of efferent innervation patterns among the three species are discussed.

  16. Efferent innervation of turtle semicircular canal cristae: comparisons with bird and mouse

    PubMed Central

    Jordan, Paivi M.; Fettis, Margaret; Holt, Joseph C.

    2014-01-01

    In the vestibular periphery of nearly every vertebrate, cholinergic vestibular efferent neurons give rise to numerous presynaptic varicosities that target hair cells and afferent processes in the sensory neuroepithelium. Although pharmacological studies have described the postsynaptic actions of vestibular efferent stimulation in several species, characterization of efferent innervation patterns and the relative distribution of efferent varicosities among hair cells and afferents are also integral to understanding how efferent synapses operate. Vestibular efferent markers, however, have not been well characterized in the turtle, one of the animal models utilized by our laboratory. Here, we sought to identify reliable efferent neuronal markers in the vestibular periphery of turtle, to utilize these markers to understand how efferent synapses are organized, and to compare efferent neuronal labeling patterns in turtle with two other amniotes using some of the same markers. Efferent fibers and varicosities were visualized in the semicircular canal of Red-Eared Turtles (Trachemys scripta elegans), Zebra Finches (Taeniopygia guttata), and mice (Mus musculus) utilizing fluorescent immunohistochemistry with antibodies against choline acetyltransferase (ChAT). Vestibular hair cells and afferents were counterstained using antibodies to myosin VIIa and calretinin. In all species, ChAT labeled a population of small diameter fibers giving rise to numerous spherical varicosities abutting type II hair cells and afferent processes. That these ChAT-positive varicosities represent presynaptic release sites were demonstrated by colabeling with antibodies against the synaptic vesicle proteins synapsin I, SV2, or syntaxin and the neuropeptide calcitonin gene-related peptide (CGRP). Comparisons of efferent innervation patterns among the three species are discussed. PMID:25560461

  17. Callose deposition during gravitropism of Zea mays and Pisum sativum and its inhibition by 2-deoxy-D-glucose

    NASA Technical Reports Server (NTRS)

    Jaffe, M. J.; Leopold, A. C.

    1984-01-01

    In etiolated corn (Zea mays L.) and etiolated pea (Pisum sativum L.) seedlings, a gravitropic stimulation induces the deposition of callose. In the corn coleoptiles this occurs within 5 min of gravity stimulation, and prior to the beginning of curvature. Both gravitropic curvature and callose deposition reach their maxima by 12 h. Within the first 2 h more callose is deposited on the upper (concave) side, but after 2-3 h, this deposition pattern is reversed. An inhibitor of protein glycosylation, 2-deoxy-D-glucose (DDG), inhibits callose production and considerably retards gravitropic bending in both species of plants. Mannose can relieve the inhibition of gravitropic bending by DDG. The pea mutant "Ageotropum", which does not respond to gravity when etiolated, also fails to produce callose in response to a gravitic stimulus. These correlations indicate that callose deposition may be a biochemical component of gravitropism in plant shoots.

  18. Functional recovery of callosal axons following demyelination: a critical window.

    PubMed

    Crawford, D K; Mangiardi, M; Xia, X; López-Valdés, H E; Tiwari-Woodruff, S K

    2009-12-29

    Axonal dysfunction as a result of persistent demyelination has been increasingly appreciated as a cause of functional deficit in demyelinating diseases such as multiple sclerosis. Therefore, it is crucial to understand the ultimate causes of ongoing axonal dysfunction and find effective measures to prevent axon loss. Our findings related to functional deficit and functional recovery of axons from a demyelinating insult are important preliminary steps towards understanding this issue. Cuprizone diet for 3-6 wks triggered extensive corpus callosum (CC) demyelination, reduced axon conduction, and resulted in loss of axon structural integrity including nodes of Ranvier. Replacing cuprizone diet with normal diet led to regeneration of myelin, but did not fully reverse the conduction and structural deficits. A shorter 1.5 wk cuprizone diet also caused demyelination of the CC, with minimal loss of axon structure and nodal organization. Switching to normal diet led to remyelination and restored callosal axon conduction to normal levels. Our findings suggest the existence of a critical window of time for remyelination, beyond which demyelinated axons become damaged beyond the point of repair and permanent functional loss follows. Moreover, initiating remyelination early within the critical period, before prolonged demyelination-induced axon damage ensues, will improve functional axon recovery and inhibit disease progression. PMID:19800949

  19. Associations between mobility, cognition and callosal integrity in people with parkinsonism

    PubMed Central

    Fling, Brett W.; Dale, Marian L.; Curtze, Carolin; Smulders, Katrijn; Nutt, John G.; Horak, Fay B.

    2016-01-01

    Falls in people with parkinsonism are likely related to both motor and cognitive impairments. In addition to idiopathic Parkinson's disease (PD), some older adults have lower body parkinsonism (a frontal gait disorder), characterized by impaired lower extremity balance and gait as well as cognition, but without tremor or rigidity. Neuroimaging during virtual gait suggests that interhemispheric, prefrontal cortex communication may be involved in locomotion, but contributions of neuroanatomy connecting these regions to objective measures of gait in people with parkinsonism remains unknown. Our objectives were to compare the integrity of fiber tracts connecting prefrontal and sensorimotor cortical regions via the corpus callosum in people with two types of parkinsonism and an age-matched control group and to relate integrity of these callosal fibers with clinical and objective measures of mobility and cognition. We recruited 10 patients with frontal gait disorders, 10 patients with idiopathic PD and 10 age-matched healthy control participants. Participants underwent cognitive and mobility testing as well as diffusion weighted magnetic resonance imaging to quantify white matter microstructural integrity of interhemispheric fiber tracts. People with frontal gait disorders displayed poorer cognitive performance and a slower, wider-based gait compared to subjects with PD and age-matched control subjects. Despite a widespread network of reduced white matter integrity in people with frontal gait disorders, gait and cognitive deficits were solely related to interhemispheric circuitry employing the genu of the corpus callosum. Current results highlight the importance of prefrontal interhemispheric communication for lower extremity control in neurological patients with cognitive dysfunction. PMID:27104136

  20. Protooncogene Ski cooperates with the chromatin-remodeling factor Satb2 in specifying callosal neurons

    PubMed Central

    Baranek, Constanze; Dittrich, Manuela; Parthasarathy, Srinivas; Bonnon, Carine Gaiser; Britanova, Olga; Lanshakov, Dmitriy; Boukhtouche, Fatiha; Sommer, Julia E.; Colmenares, Clemencia; Tarabykin, Victor; Atanasoski, Suzana

    2012-01-01

    First insights into the molecular programs orchestrating the progression from neural stem cells to cortical projection neurons are emerging. Loss of the transcriptional regulator Ski has been linked to the human 1p36 deletion syndrome, which includes central nervous system defects. Here, we report critical roles for Ski in the maintenance of the neural stem cell pool and the specification of callosal neurons. Ski-deficient callosal neurons lose their identity and ectopically express the transcription factor Ctip2. The misspecified callosal neurons largely fail to form the corpus callosum and instead redirect their axons toward subcortical targets. We identify the chromatin-remodeling factor Satb2 as a partner of Ski, and show that both proteins are required for transcriptional repression of Ctip2 in callosal neurons. We propose a model in which Satb2 recruits Ski to the Ctip2 locus, and Ski attracts histone deacetylases, thereby enabling the formation of a functional nucleosome remodeling and deacetylase repressor complex. Our findings establish a central role for Ski–Satb2 interactions in regulating transcriptional mechanisms of callosal neuron specification. PMID:22334647

  1. Isolated cystic lesion of the callosal genu after traumatic brain injury.

    PubMed

    Kato, Toru; Okumura, Akihisa; Tsuji, Takeshi; Emi, Misugi; Natsume, Jun

    2012-06-01

    We report the case of a 17-month-old infant who developed an isolated cystic lesion of the callosal genu as a unique lesion of traumatic axonal injury (TAI). Although one of the most common sites of TAI is the corpus callosum, there have been no reports describing the lesion seen in our patient. Brain computed tomography findings were normal on the day of the traffic accident. After 3 months, brain magnetic resonance imaging showed an isolated cystic lesion of the callosal genu that had the appearance of a cystic cavity. This lesion decreased in size 16 months later. The neuroimaging findings of this patient suggest that an isolated cystic lesion of the callosal genu could appear as a unique form of TAI in infants after traumatic brain injury (TBI), but it is nevertheless important to attend to such lesions in children with TBI.

  2. Three-dimensional analysis of vestibular efferent neurons innervating semicircular canals of the gerbil

    NASA Technical Reports Server (NTRS)

    Purcell, I. M.; Perachio, A. A.

    1997-01-01

    Anterograde labeling techniques were used to examine peripheral innervation patterns of vestibular efferent neurons in the crista ampullares of the gerbil. Vestibular efferent neurons were labeled by extracellular injections of biocytin or biotinylated dextran amine into the contralateral or ipsilateral dorsal subgroup of efferent cell bodies (group e) located dorsolateral to the facial nerve genu. Anterogradely labeled efferent terminal field varicosities consist mainly of boutons en passant with fewer of the terminal type. The bouton swellings are located predominately in apposition to the basolateral borders of the afferent calyces and type II hair cells, but several boutons were identified close to the hair cell apical border on both types. Three-dimensional reconstruction and morphological analysis of the terminal fields from these cells located in the sensory neuroepithelium of the anterior, horizontal, and posterior cristae were performed. We show that efferent neurons densely innervate each end organ in widespread terminal fields. Subepithelial bifurcations of parent axons were minimal, with extensive collateralization occurring after the axons penetrated the basement membrane of the neuroepithelium. Axonal branching ranged between the 6th and 27th orders and terminal field collecting area far exceeds that of the peripheral terminals of primary afferent neurons. The terminal fields of the efferent neurons display three morphologically heterogeneous types: central, peripheral, and planum. All cell types possess terminal fields displaying a high degree of anisotropy with orientations typically parallel to or within +/-45 degrees of the longitudinal axis if the crista. Terminal fields of the central and planum zones predominately project medially toward the transverse axis from the more laterally located penetration of the basement membrane by the parent axon. Peripheral zone terminal fields extend predominately toward the planum semilunatum. The innervation

  3. Retrograde transport of (/sup 3/H)-D-aspartate label by cochlear and vestibular efferent neurons

    SciTech Connect

    Schwarz, D.W.; Schwarz, I.E.

    1988-01-01

    (/sup 3/H)-D-aspartic acid was injected into the inner ear of rats. After a six hour survival time, labeled cells were found at all locations known to contain efferent cochlear or vestibular neurons. Most labeled neurons were found in the ipsilateral lateral superior olivary nucleus (LSO), although both ventral nuclei of the trapezoid body (VTB), group E, and the caudal pontine reticular nucleus (CPR) just adjacent to the ascending limb of the facial nerve also contained labeled cells. Because not all efferent neurons in the rat could be previously shown to be cholinergic, aspartate and glutamate are efferent transmitter candidates.

  4. Active sensing without efference copy: referent control of perception.

    PubMed

    Feldman, Anatol G

    2016-09-01

    Although action and perception are different behaviors, they are likely to be interrelated, as implied by the notions of perception-action coupling and active sensing. Traditionally, it has been assumed that the nervous system directly preprograms motor commands required for actions and uses a copy of them called efference copy (EC) to also influence our senses. This review offers a critical analysis of the EC concept by identifying its limitations. An alternative to the EC concept is based on the experimentally confirmed notion that sensory signals from receptors are perceived relative to referent signals specified by the brain. These referents also underlie the control of motor actions by predetermining where, in the spatial domain, muscles can work without preprogramming how they should work in terms of motor commands or EC. This approach helps solve several problems of action and explain several sensory experiences, including position sense and the sense that the world remains stationary despite changes in its retinal image during eye or body motion (visual space constancy). The phantom limb phenomenon and other kinesthetic illusions are also explained within this framework. PMID:27306668

  5. Evidence against a hypothesis of vestibular efferent function

    NASA Technical Reports Server (NTRS)

    Cochran, S. L.

    1994-01-01

    Efferent stimulation and nicotinic agonists can either decrease or increase the frequency of occurrence of EPSPs recorded from VIIIth nerve afferents in the frog. It has been hypothesized that the distribution of hair cell resting membrane potentials overlaps the equilibrium potential dictated by the nicotinic-gated channels on the hair cells. Nicotinic mediated increases in EPSP frequency would then be due to depolarization of hair cells that were more hyperpolarized at rest, while decreases in EPSP frequency would be due to hyperpolarization of hair cells more depolarized at rest. In order to test this hypothesis, while recording from afferents which showed an increase in EPSP frequency due to bath application of the nicotinic agonist DMPP (1,1-dimethyl-4-phenylpiperizinium iodide), hair cells were depolarized with 10 mM K+ in the bath, and then the effects of DMPP on EPSP frequency were assessed. In this situation, DMPP still increased EPSP frequency, suggesting that the equilibrium potential for the nicotinic-gated channel was much more positive than the resting potentials of the hair cells. An alternative hypothesis then seems likely, that the nicotinic receptors on hair cells are able to activate different iontophores that result in either hair cell depolarization or hyperpolarization, dependent upon which iontophore predominates in the hair cells innervating a particular afferent.

  6. Neurodegeneration of lateral habenula efferent fibers after intermittent cocaine administration: implications for deep brain stimulation.

    PubMed

    Lax, Elad; Friedman, Alexander; Croitoru, Ofri; Sudai, Einav; Ben-Moshe, Hila; Redlus, Lior; Sasson, Efrat; Blumenfeld-Katzir, Tamar; Assaf, Yaniv; Yadid, Gal

    2013-12-01

    Deep brain stimulation (DBS) is an emerging technique for effective, non-pharmacological intervention in the course of neurological and neuropsychiatric diseases. Several brain targets have been suggested as suitable for DBS treatment of drug addiction. Previously, we showed that DBS of the lateral habenula (LHb) can reduce cocaine intake, facilitate extinction and attenuate drug-induced relapse in rats trained to self-administrate cocaine. Herein, we demonstrated that cocaine self-administration dose-dependently decreased connectivity between the LHb and midbrain, as shown by neurodegeneration of the main LHb efferent fiber, the fasciculus retroflexus (FR). FR degeneration, in turn, may have caused lack of response to LHb stimulation in rats trained to self-administer high-dose cocaine (1.5 mg/kg; i.v.). Furthermore, we show that the micro-structural changes caused by cocaine can be non-invasively detected using magnetic resonance imaging and diffusion tensor imaging. Detection of cocaine-induced alterations in FR anatomy can aid the selection of potential responders to LHb stimulation for treatment of drug addiction. PMID:23891640

  7. Pharmacologically Distinct Nicotinic Acetylcholine Receptors Drive Efferent-Mediated Excitation in Calyx-Bearing Vestibular Afferents

    PubMed Central

    Kewin, Kevin; Jordan, Paivi M.; Cameron, Peter; Klapczynski, Marcin; McIntosh, J. Michael; Crooks, Peter A.; Dwoskin, Linda P.; Lysakowski, Anna

    2015-01-01

    Electrical stimulation of vestibular efferent neurons rapidly excites the resting discharge of calyx/dimorphic (CD) afferents. In turtle, this excitation arises when acetylcholine (ACh), released from efferent terminals, directly depolarizes calyceal endings by activating nicotinic ACh receptors (nAChRs). Although molecular biological data from the peripheral vestibular system implicate most of the known nAChR subunits, specific information about those contributing to efferent-mediated excitation of CD afferents is lacking. We sought to identify the nAChR subunits that underlie the rapid excitation of CD afferents and whether they differ from α9α10 nAChRs on type II hair cells that drive efferent-mediated inhibition in adjacent bouton afferents. We recorded from CD and bouton afferents innervating the turtle posterior crista during electrical stimulation of vestibular efferents while applying several subtype-selective nAChR agonists and antagonists. The α9α10 nAChR antagonists, α-bungarotoxin and α-conotoxin RgIA, blocked efferent-mediated inhibition in bouton afferents while leaving efferent-mediated excitation in CD units largely intact. Conversely, 5-iodo-A-85380, sazetidine-A, varenicline, α-conotoxin MII, and bPiDDB (N,N-dodecane-1,12-diyl-bis-3-picolinium dibromide) blocked efferent-mediated excitation in CD afferents without affecting efferent-mediated inhibition in bouton afferents. This pharmacological profile suggested that calyceal nAChRs contain α6 and β2, but not α9, nAChR subunits. Selective blockade of efferent-mediated excitation in CD afferents distinguished dimorphic from calyx afferents by revealing type II hair cell input. Dimorphic afferents differed in having higher mean discharge rates and a mean efferent-mediated excitation that was smaller in amplitude yet longer in duration. Molecular biological data demonstrated the expression of α9 in turtle hair cells and α4 and β2 in associated vestibular ganglia. PMID:25716861

  8. Connectivity

    ERIC Educational Resources Information Center

    Grush, Mary, Ed.

    2006-01-01

    Connectivity has dramatically changed the landscape of higher education IT. From "on-demand" services for net-gen students and advanced eLearning systems for faculty, to high-performance computing grid resources for researchers, IT now provides more networked services than ever to connect campus constituents to each other and to the world.…

  9. Iron-dependent callose deposition adjusts root meristem maintenance to phosphate availability.

    PubMed

    Müller, Jens; Toev, Theresa; Heisters, Marcus; Teller, Janine; Moore, Katie L; Hause, Gerd; Dinesh, Dhurvas Chandrasekaran; Bürstenbinder, Katharina; Abel, Steffen

    2015-04-20

    Plant root development is informed by numerous edaphic cues. Phosphate (Pi) availability impacts the root system architecture by adjusting meristem activity. However, the sensory mechanisms monitoring external Pi status are elusive. Two functionally interacting Arabidopsis genes, LPR1 (ferroxidase) and PDR2 (P5-type ATPase), are key players in root Pi sensing, which is modified by iron (Fe) availability. We show that the LPR1-PDR2 module facilitates, upon Pi limitation, cell-specific apoplastic Fe and callose deposition in the meristem and elongation zone of primary roots. Expression of cell-wall-targeted LPR1 determines the sites of Fe accumulation as well as callose production, which interferes with symplastic communication in the stem cell niche, as demonstrated by impaired SHORT-ROOT movement. Antagonistic interactions of Pi and Fe availability control primary root growth via meristem-specific callose formation, likely triggered by LPR1-dependent redox signaling. Our results link callose-regulated cell-to-cell signaling in root meristems to the perception of an abiotic cue.

  10. The Plasmodesmal Protein PDLP1 Localises to Haustoria-Associated Membranes during Downy Mildew Infection and Regulates Callose Deposition

    PubMed Central

    Sklenar, Jan; Findlay, Kim; Piquerez, Sophie J. M.; Jones, Alexandra M. E.; Robatzek, Silke; Jones, Jonathan D. G.; Faulkner, Christine

    2014-01-01

    The downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa) is a filamentous oomycete that invades plant cells via sophisticated but poorly understood structures called haustoria. Haustoria are separated from the host cell cytoplasm and surrounded by an extrahaustorial membrane (EHM) of unknown origin. In some interactions, including Hpa-Arabidopsis, haustoria are progressively encased by host-derived, callose-rich materials but the molecular mechanisms by which callose accumulates around haustoria remain unclear. Here, we report that PLASMODESMATA-LOCATED PROTEIN 1 (PDLP1) is expressed at high levels in Hpa infected cells. Unlike other plasma membrane proteins, which are often excluded from the EHM, PDLP1 is located at the EHM in Hpa-infected cells prior to encasement. The transmembrane domain and cytoplasmic tail of PDLP1 are sufficient to convey this localization. PDLP1 also associates with the developing encasement but this association is lost when encasements are fully mature. We found that the pdlp1,2,3 triple mutant is more susceptible to Hpa while overexpression of PDLP1 enhances plant resistance, suggesting that PDLPs enhance basal immunity against Hpa. Haustorial encasements are depleted in callose in pdlp1,2,3 mutant plants whereas PDLP1 over-expression elevates callose deposition around haustoria and across the cell surface. These data indicate that PDLPs contribute to callose encasement of Hpa haustoria and suggests that the deposition of callose at haustoria may involve similar mechanisms to callose deposition at plasmodesmata. PMID:25393742

  11. Localization and Quantification of Callose in the Streptophyte Green Algae Zygnema and Klebsormidium: Correlation with Desiccation Tolerance

    PubMed Central

    Herburger, Klaus; Holzinger, Andreas

    2015-01-01

    Freshwater green algae started to colonize terrestrial habitats about 460 million years ago, giving rise to the evolution of land plants. Today, several streptophyte green algae occur in aero-terrestrial habitats with unpredictable fluctuations in water availability, serving as ideal models for investigating desiccation tolerance. We tested the hypothesis that callose, a β-d-1,3-glucan, is incorporated specifically in strained areas of the cell wall due to cellular water loss, implicating a contribution to desiccation tolerance. In the early diverging genus Klebsormidium, callose was drastically increased already after 30 min of desiccation stress. Localization studies demonstrated an increase in callose in the undulating cross cell walls during cellular water loss, allowing a regulated shrinkage and expansion after rehydration. This correlates with a high desiccation tolerance demonstrated by a full recovery of the photosynthetic yield visualized at the subcellular level by Imaging-PAM. Furthermore, abundant callose in terminal cell walls might facilitate cell detachment to release dispersal units. In contrast, in the late diverging Zygnema, the callose content did not change upon desiccation for up to 3.5 h and was primarily localized in the corners between individual cells and at terminal cells. While these callose deposits still imply reduction of mechanical damage, the photosynthetic yield did not recover fully in the investigated young cultures of Zygnema upon rehydration. The abundance and specific localization of callose correlates with the higher desiccation tolerance in Klebsormidium when compared with Zygnema. PMID:26412780

  12. Callose Deposition Is Responsible for Apoplastic Semipermeability of the Endosperm Envelope of Muskmelon Seeds1

    PubMed Central

    Yim, Kyu-Ock; Bradford, Kent J.

    1998-01-01

    Semipermeable cell walls or apoplastic “membranes” have been hypothesized to be present in various plant tissues. Although often associated with suberized or lignified walls, the wall component that confers osmotic semipermeability is not known. In muskmelon (Cucumis melo L.) seeds, a thin, membranous endosperm completely encloses the embryo, creating a semipermeable apoplastic envelope. When dead muskmelon seeds are allowed to imbibe, solutes leaking from the embryo are retained within the envelope, resulting in osmotic water uptake and swelling called osmotic distention (OD). The endosperm envelope of muskmelon seeds stained with aniline blue, which is specific for callose (β-1,3-glucan). Outside of the aniline-blue-stained layer was a Sudan III- and IV-staining (lipid-containing) layer. In young developing seeds 25 d after anthesis (DAA) that did not exhibit OD, the lipid layer was already present but callose had not been deposited. At 35 DAA, callose was detected as distinct vesicles or globules in the endosperm envelope. A thick callose layer was evident at 40 DAA, coinciding with development of the capacity for OD. Removal of the outer lipid layer by brief chloroform treatment resulted in more rapid water uptake by both viable and nonviable (boiled) seeds, but did not affect semipermeability of the endosperm envelope. The aniline-blue-staining layer was digested by β-1,3-glucanase, and these envelopes lost OD. Thus, apoplastic semipermeability of the muskmelon endosperm envelope is dependent on the deposition of a thick callose-containing layer outside of the endosperm cell walls. PMID:9733528

  13. Altered callose deposition during embryo sac formation of multi-pistil mutant (mp1) in Medicago sativa.

    PubMed

    Zhou, H C; Jin, L; Li, J; Wang, X J

    2016-01-01

    Whether callose deposition is the cause or result of ovule sterility in Medicago sativa remains controversial, because it is unclear when and where changes in callose deposition and dissolution occur during fertile and sterile embryo sac formation. Here, alfalfa spontaneous multi-pistil mutant (mp1) and wild-type plants were used to compare the dynamics of callose deposition during embryo sac formation using microscopy. The results showed that both mutant and wild-type plants experienced megasporogenesis and megagametogenesis, and there was no significant difference during megasporogenesis. In contrast to the wild-type plants, in which the mature embryo sac was observed after three continuous cycles of mitosis, functional megaspores of mutant plants developed abnormally after the second round of mitosis, leading to degeneration of synergid, central, and antipodal cells. Callose deposition in both mutant and wild-type plants was first observed in the walls of megasporocytes, and then in the megaspore tetrad walls. After meiosis, the callose wall began to degrade as the functional megaspore underwent mitosis, and almost no callose was observed in the mature embryo sac in wild-type plants. However, callose deposition was observed in mp1 plants around the synergid, and increased with the development of the embryo sac, and was mainly deposited at the micropylar end. Our results indicate that synergid, central, and antipodal cells, which are surrounded by callose, may degrade owing to lack of nutrition. Callose accumulation around the synergid and at the micropylar end may hinder signals required for the pollen tube to enter the embryo sac, leading to abortion. PMID:27323128

  14. Quantitative Proteomics Reveals that Plasma Membrane Microdomains From Poplar Cell Suspension Cultures Are Enriched in Markers of Signal Transduction, Molecular Transport, and Callose Biosynthesis*

    PubMed Central

    Srivastava, Vaibhav; Malm, Erik; Sundqvist, Gustav; Bulone, Vincent

    2013-01-01

    The plasma membrane (PM) is a highly dynamic interface that contains detergent-resistant microdomains (DRMs). The aim of this work was to determine the main functions of such microdomains in poplar through a proteomic analysis using gel-based and solution (iTRAQ) approaches. A total of 80 proteins from a limited number of functional classes were found to be significantly enriched in DRM relative to PM. The enriched proteins are markers of signal transduction, molecular transport at the PM, or cell wall biosynthesis. Their intrinsic properties are presented and discussed together with the biological significance of their enrichment in DRM. Of particular importance is the significant and specific enrichment of several callose [(1→3)-β-glucan] synthase isoforms, whose catalytic activity represents a final response to stress, leading to the deposition of callose plugs at the surface of the PM. An integrated functional model that connects all DRM-enriched proteins identified is proposed. This report is the only quantitative analysis available to date of the protein composition of membrane microdomains from a tree species. PMID:24051156

  15. Response properties of cochlear efferent neurons: monaural vs. binaural stimulation and the effects of noise.

    PubMed

    Liberman, M C

    1988-11-01

    1. Discharge properties of olivocochlear efferent neurons were measured in anesthetized cats. Previous studies of these neurons concentrated on monaural stimulation with tones and found sound-evoked discharge rates rarely exceeded 60 spikes/s (16, 20). In the present study, rates as high as 140 spikes/s were achieved by binaural stimulation and/or the addition of noise. Based on studies on the known effects of electrically stimulating the efferents such high rates of sound-evoked efferent activity probably have significant feedback effects on the auditory periphery. 2. Spontaneous discharge rate (SR) was weakly correlated with threshold among efferent neurons: those with SRs greater than 1 spikes/s were generally more sensitive than spontaneously inactive fibers. The discharge rate measured in the absence of acoustic stimulation was shown to be dependent on stimulation history: some units with zero SR became spontaneously active after several minutes of continuous noise stimulation. 3. For stimulation with monaural tones, efferent excitability varied with characteristic frequency (CF): units with CF less than 10 kHz tended to have lower thresholds, higher discharge rates, and shorter latencies than higher CF units. These differences could be minimized by the addition of broadband noise (see below). 4. When tones were presented to one ear at a time, most efferent units appeared monaural (91%), with roughly two-thirds excited by ipsilateral stimuli and one-third by contralateral stimuli. However, the effects of simultaneous stimulation of the two ears suggested that the great majority of efferent units have binaural inputs: the addition of opposite-ear noise or tones, which presented alone were not excitatory, typically enhanced the response to main-ear stimulation. This type of binaural facilitation was strongest among low-CF efferents when the opposite-ear stimuli were tones, and strongest among high-CF units when the opposite-ear stimulus was broadband noise. 5

  16. Evolution and development of hair cell polarity and efferent function in the inner ear.

    PubMed

    Sienknecht, Ulrike J; Köppl, Christine; Fritzsch, Bernd

    2014-01-01

    The function of the inner ear critically depends on mechanoelectrically transducing hair cells and their afferent and efferent innervation. The first part of this review presents data on the evolution and development of polarized vertebrate hair cells that generate a sensitive axis for mechanical stimulation, an essential part of the function of hair cells. Beyond the cellular level, a coordinated alignment of polarized hair cells across a sensory epithelium, a phenomenon called planar cell polarity (PCP), is essential for the organ's function. The coordinated alignment of hair cells leads to hair cell orientation patterns that are characteristic of the different sensory epithelia of the vertebrate inner ear. Here, we review the developmental mechanisms that potentially generate molecular and morphological asymmetries necessary for the control of PCP. In the second part, this review concentrates on the evolution, development and function of the enigmatic efferent neurons terminating on hair cells. We present evidence suggestive of efferents being derived from motoneurons and synapsing predominantly onto a unique but ancient cholinergic receptor. A review of functional data shows that the plesiomorphic role of the efferent system likely was to globally shut down and protect the peripheral sensors, be they vestibular, lateral line or auditory hair cells, from desensitization and damage during situations of self-induced sensory overload. The addition of a dedicated auditory papilla in land vertebrates appears to have favored the separation of vestibular and auditory efferents and specializations for more sophisticated and more diverse functions.

  17. Dynamic Behavior Analysis of the Glomerulo-Tubular Balance Mediated by the Efferent Blood Viscosity

    NASA Astrophysics Data System (ADS)

    Espinel, Andrea; Rivadeneira, Pablo S.; Costanza, Vicente; Amorena, Carlos

    In this paper, a mathematical model of the dynamics of a single-nephron function relating glomerulo-tubular balance, tubule-glomerular feedback, and peritubular blood viscosity is developed. Based upon experimental data, the model shows that complex behaviors of the nephron can be modulated by changes in the efferent arteriole blood viscosity. The main hypothesis is that the reabsorbed mass flow is modulated by the hematocrit of the efferent arteriole, in addition to the Starling forces. From a mathematical perspective, these behaviors can be explained by a bifurcation diagram analysis where the efferent blood viscosity is taken as the bifurcation parameter. This analytical description allows to predict changes in proximal convoluted tubule reabsorption, following changes in peritubular capillary viscosity generated by periodic changes in the glomerular filtration rate. Thus, the model links the tubule-glomerular feedback with the glomerular tubular balance.

  18. Influence of medial olivocochlear efferents on the sharpness of cochlear tuning estimates in children.

    PubMed

    Mishra, Srikanta K; Dinger, Zoë

    2016-08-01

    The present study objectively quantified the efferent-induced changes in the sharpness of cochlear tuning estimates and compared these alterations in cochlear tuning between adults and children. Click evoked otoacoustic emissions with and without contralateral broadband noise were recorded from 15 young adults and 14 children aged between 5 and 10 yrs. Time-frequency distributions of click evoked otoacoustic emissions were obtained via the S-transform, and the otoacoustic emission latencies were used to estimate the sharpness of cochlear tuning. Contralateral acoustic stimulation caused a significant reduction in the sharpness of cochlear tuning estimates in the low to mid frequency region, but had no effect in the higher frequencies (3175 and 4000 Hz). The magnitude of efferent-induced changes in cochlear tuning estimates was similar between adults and children. The current evidence suggests that the stimulation of the medial olivocochlear efferent neurons causes similar alterations in cochlear frequency selectivity in adults and children. PMID:27586737

  19. Callosal atrophy in mild cognitive impairment and Alzheimer's disease: different effects in different stages.

    PubMed

    Di Paola, Margherita; Luders, Eileen; Di Iulio, Fulvia; Cherubini, Andrea; Passafiume, Domenico; Thompson, Paul M; Caltagirone, Carlo; Toga, Arthur W; Spalletta, Gianfranco

    2010-01-01

    Alzheimer's Disease (AD) is a neurodegenerative disorder that mainly affects grey matter (GM). Nevertheless, a number of investigations have documented white matter (WM) pathology associated with AD. The corpus callosum (CC) is the largest WM fiber bundle in the human brain. It has been shown to be susceptible to atrophy in AD mainly as a correlate of Wallerian degeneration of commissural nerve fibers of the neocortex. The aim of this study was to investigate which callosal regions are affected and whether callosal degeneration is associated with the stage of the disease. For this purpose, we analyzed high-resolution MRI data of patients with amnesic mild cognitive impairment (MCI) (n=20), mild AD (n=20), severe AD (n=10), and of healthy controls (n=20). Callosal morphology was investigated applying two different structural techniques: mesh-based geometrical modeling methods and whole-brain voxel-based analyses. Our findings indicate significant reductions in severe AD patients compared to healthy controls in anterior (genu and anterior body) and posterior (splenium) sections. In contrast, differences between healthy controls and mild AD patients or amnesic MCI patients were less pronounced and did not survive corrections for multiple comparisons. When correlating anterior and posterior WM density of the CC with GM density of the cortex in the severe AD group, we detected significant positive relationships between posterior sections of the CC and the cortex. We conclude that callosal atrophy is present predominantly in the latest stage of AD, where two mechanisms might contribute to WM alterations in severe AD: the Wallerian degeneration in posterior subregions and the myelin breakdown process in anterior subregions.

  20. Induction of Embryogenesis in Brassica Napus Microspores Produces a Callosic Subintinal Layer and Abnormal Cell Walls with Altered Levels of Callose and Cellulose

    PubMed Central

    Parra-Vega, Verónica; Corral-Martínez, Patricia; Rivas-Sendra, Alba; Seguí-Simarro, Jose M.

    2015-01-01

    The induction of microspore embryogenesis produces dramatic changes in different aspects of the cell physiology and structure. Changes at the cell wall level are among the most intriguing and poorly understood. In this work, we used high pressure freezing and freeze substitution, immunolocalization, confocal, and electron microscopy to analyze the structure and composition of the first cell walls formed during conventional Brassica napus microspore embryogenesis, and in cultures treated to alter the intracellular Ca2+ levels. Our results revealed that one of the first signs of embryogenic commitment is the formation of a callose-rich, cellulose-deficient layer beneath the intine (the subintinal layer), and of irregular, incomplete cell walls. In these events, Ca2+ may have a role. We propose that abnormal cell walls are due to a massive callose synthesis and deposition of excreted cytoplasmic material, and the parallel inhibition of cellulose synthesis. These features were absent in pollen-like structures and in microspore-derived embryos, few days after the end of the heat shock, where abnormal cell walls were no longer produced. Together, our results provide an explanation to a series of relevant aspects of microspore embryogenesis including the role of Ca2+ and the occurrence of abnormal cell walls. In addition, our discovery may be the explanation to why nuclear fusions take place during microspore embryogenesis. PMID:26635844

  1. Binaural noise stimulation of auditory callosal fibers of the cat: responses to interaural time delays.

    PubMed

    Poirier, P; Lepore, F; Provençal, C; Ptito, M; Guillemot, J P

    1995-01-01

    The corpus callosum, the principal neocortical commissure, allows for the interhemispheric transfer of lateralized information between the hemispheres. The aim of the present experiment was to study callosal transfer of auditory information in the cat, with particular reference to its contribution to sound localization. The corpus callosum was approached under direct visual control, and axonic responses were recorded under light anesthesia using glass micro-pipettes. Results showed that auditory information is transmitted in the posterior portion of the callosum. Diotic presentations, in which interaural time delay was manipulated, indicated that, for a large number of fibers, the largest excitatory or inhibitory interactions were obtained at null interaural time delay, a condition which supports the notion of a callosal contribution to auditory midline fusion. However, an important number of callosal fibers was also found to be excited maximally at specific, non-zero interaural time delays, suggesting that they preferred sounds situated at spatial locations other than the midline. The results are discussed in relation to those obtained electrophysiologically for the visual and somesthesic modalities and in terms of results obtained in human and animal behavioral experiments.

  2. The Efferent System or Olivocochlear Function Bundle – Fine Regulator and Protector of Hearing Perception

    PubMed Central

    Ciuman, Raphael Richard

    2010-01-01

    The efferent system of the ear possesses several distinct functions, in particular noise protection, mediation of selective attention and improvement of signal to noise ratio. It also supports adaptation and frequency selectivity by modification of the micromechanical properties of outer hair cells. There are many differences in anatomy and physiology between the medial and lateral olivocochlear system suggesting that they are functionally separate systems. The efferent system is affected by inner ear stressors, e.g. noise, ototoxic drugs, and might play a key role in tinnitus generation and maintenance. The anatomy, physiology and its realtionships to inner ear pathologies are discussed in this review article. PMID:23675203

  3. Ninth Grade Students' Negotiation of Aesthetic, Efferent, and Critical Stances in Response to a Novel Set in Afghanistan

    ERIC Educational Resources Information Center

    Taliaferro, Cheryl

    2011-01-01

    This qualitative, action research study was guided by two primary research questions. First, how do students negotiate aesthetic, efferent, and critical stances when reading a novel set in Afghanistan? Second, how do aesthetic and efferent stances contribute to or hinder the adoption of a critical stance? A large body of research exists that…

  4. Organization of the output of the ventral striatopallidal system in the rat: ventral pallidal efferents.

    PubMed

    Groenewegen, H J; Berendse, H W; Haber, S N

    1993-11-01

    The efferent projections of the ventral pallidum in the rat were studied using anterograde tracing of Phaseolus vulgaris-leucoagglutinin and retrograde tracing of choleratoxin subunit B. The main aim of this study was to determine the degree of topographical organization in the outputs of the ventral pallidum. In the telencephalon, ventral pallidal fibers reach the prefrontal cortex, the ventral striatum, the lateral septum, the basolateral, lateral, and central amygdaloid nuclei, and the lateral entorhinal area. Diencephalic targets of ventral pallidal fibers are the lateral hypothalamus, the reticular nucleus of the thalamus, the mediodorsal thalamic nucleus, the dorsomedial part of the subthalamic nucleus, the medial part of the parafascicular nucleus and the lateral habenula. In the mesencephalon, ventral pallidal fibers terminate in the ventral tegmental area, the substantia nigra, the retrorubral area, the median raphe nucleus, the nucleus raphe magnus, the peribrachial area, the ventromedial part of the central gray substance and the locus coeruleus. The results of the experiments in which retrograde tracers were injected in different nuclei in the mesencephalon allow the distinction of two main areas in the ventral pallidum. Deposits of retrograde tracers in the substantia nigra, pars reticulata result in labeling of cells in the dorsolateral part of the ventral pallidum, located immediately ventral to the anterior limb of the anterior commissure. Retrograde tracer injections in other targets of the ventral mesencephalon, i.e. the dopaminergic cell groups A10, A9 or A8, or nuclei in the peribrachial area result in labeling of neurons in an extensive ventromedial and ventrolateral zone of the ventral pallidum. The medial part of this ventral pallidal zone projects to the ventral tegmental area, whereas ventral and lateral parts connect with more lateral and caudal mesencephalic targets. The projections from the ventral pallidum to the ventral striatum, the

  5. Afferent and Efferent Aspects of Mandibular Sensorimotor Control in Adults Who Stutter

    ERIC Educational Resources Information Center

    Daliri, Ayoub; Prokopenko, Roman A.; Max, Ludo

    2013-01-01

    Purpose: Individuals who stutter show sensorimotor deficiencies in speech and nonspeech movements. For the mandibular system, the authors dissociated the sense of kinesthesia from the efferent control component to examine whether kinesthetic integrity itself is compromised in stuttering or whether deficiencies occur only when generating motor…

  6. The vomeronasal cortex - afferent and efferent projections of the posteromedial cortical nucleus of the amygdala in mice.

    PubMed

    Gutiérrez-Castellanos, Nicolás; Pardo-Bellver, Cecília; Martínez-García, Fernando; Lanuza, Enrique

    2014-01-01

    Most mammals possess a vomeronasal system that detects predominantly chemical signals of biological relevance. Vomeronasal information is relayed to the accessory olfactory bulb (AOB), whose unique cortical target is the posteromedial cortical nucleus of the amygdala. This cortical structure should therefore be considered the primary vomeronasal cortex. In the present work, we describe the afferent and efferent connections of the posteromedial cortical nucleus of the amygdala in female mice, using anterograde (biotinylated dextranamines) and retrograde (Fluorogold) tracers, and zinc selenite as a tracer specific for zinc-enriched (putative glutamatergic) projections. The results show that the posteromedial cortical nucleus of the amygdala is strongly interconnected not only with the rest of the vomeronasal system (AOB and its target structures in the amygdala), but also with the olfactory system (piriform cortex, olfactory-recipient nuclei of the amygdala and entorhinal cortex). Therefore, the posteromedial cortical nucleus of the amygdala probably integrates olfactory and vomeronasal information. In addition, the posteromedial cortical nucleus of the amygdala shows moderate interconnections with the associative (basomedial) amygdala and with the ventral hippocampus, which may be involved in emotional and spatial learning (respectively) induced by chemical signals. Finally, the posteromedial cortical nucleus of the amygdala gives rise to zinc-enriched projections to the ventrolateral septum and the ventromedial striatum (including the medial islands of Calleja). This pattern of intracortical connections (with the olfactory cortex and hippocampus, mainly) and cortico-striatal excitatory projections (with the olfactory tubercle and septum) is consistent with its proposed nature as the primary vomeronasal cortex.

  7. Predictability of visual perturbation during locomotion: implications for corrective efference copy signaling.

    PubMed

    Chagnaud, Boris P; Simmers, John; Straka, Hans

    2012-12-01

    In guiding adaptive behavior, efference copy signals or corollary discharge are traditionally considered to serve as predictors of self-generated sensory inputs and by interfering with their central processing are able to counter unwanted consequences of an animal's own actions. Here, in a speculative reflection on this issue, we consider a different functional role for such intrinsic predictive signaling, namely in stabilizing gaze during locomotion where resultant changes in head orientation in space require online compensatory eye movements in order to prevent retinal image slip. The direct activation of extraocular motoneurons by locomotor-related efference copies offers a prospective substrate for assisting self-motion derived sensory feedback, rather than being subtracted from the sensory signal to eliminate unwanted reafferent information. However, implementing such a feed-forward mechanism would be critically dependent on an appropriate phase coupling between rhythmic propulsive movement and resultant head/visual image displacement. We used video analyzes of actual locomotor behavior and basic theoretical modeling to evaluate head motion during stable locomotion in animals as diverse as Xenopus laevis tadpoles, teleost fish and horses in order to assess the potential suitability of spinal efference copies to the stabilization of gaze during locomotion. In all three species, and therefore regardless of aquatic or terrestrial environment, the head displacements that accompanied locomotor action displayed a strong correlative spatio-temporal relationship in correspondence with a potential predictive value for compensatory eye adjustments. Although spinal central pattern generator-derived efference copies offer appropriately timed commands for extraocular motor control during self-generated motion, it is likely that precise image stabilization requires the additional contributions of sensory feedback signals. Nonetheless, the predictability of the visual

  8. A membrane-associated form of sucrose synthase and its potential role in synthesis of cellulose and callose in plants

    SciTech Connect

    Amor, Y.; Haigler, C.H.; Johnson, S.; Wainscott, M.

    1995-09-26

    Sucrose synthase (SuSy;EC2,4,1.13; sucrose + UDP{rightleftharpoons}UDPglucose + fructose) has always been studied as a cytoplasmic enzyme in plant cells where it serves to degrade sucrose and provide carbon for respiration and synthesis of cell wall polysaccharides and starch. We report here that at least half of the total SuSy of developing cotton fibers (Gossypium hirsutum) is tightly associated with the plasma membrane. Therefore, this form of SuSy might serve to channel carbon directly from sucrose to cellulose and/or callose synthases in the plasma membrane. By using detached and permeabilized cotton fibers, we show that carbon from sucrose can be converted at high rates to both cellulose and callose. Synthesis of cellulose or callose is favored by addition of EGTA or calcium and cellobiose, respectively. These findings contrast with the traditional observation that when UDPglucose is used as substrate in vitro, callose is the major product synthesized. Immunolocalization studies how that SuSy can be localized at the fiber surface in patterns consistent with the deposition of cellulose or callose. Thus, these results support a model in which SuSy exists in a complex with the {beta}-glucan synthases and serves to channel carbon from sucrose to glucan.

  9. A membrane-associated form of sucrose synthase and its potential role in synthesis of cellulose and callose in plants.

    PubMed Central

    Amor, Y; Haigler, C H; Johnson, S; Wainscott, M; Delmer, D P

    1995-01-01

    Sucrose synthase (SuSy; EC 2.4.1.13; sucrose + UDP reversible UDPglucose + fructose) has always been studied as a cytoplasmic enzyme in plant cells where it serves to degrade sucrose and provide carbon for respiration and synthesis of cell wall polysaccharides and starch. We report here that at least half of the total SuSy of developing cotton fibers (Gossypium hirsutum) is tightly associated with the plasma membrane. Therefore, this form of SuSy might serve to channel carbon directly from sucrose to cellulose and/or callose synthases in the plasma membrane. By using detached and permeabilized cotton fibers, we show that carbon from sucrose can be converted at high rates to both cellulose and callose. Synthesis of cellulose or callose is favored by addition of EGTA or calcium and cellobiose, respectively. These findings contrast with the traditional observation that when UDPglucose is used as substrate in vitro, callose is the major product synthesized. Immunolocalization studies show that SuSy can be localized at the fiber surface in patterns consistent with the deposition of cellulose or callose. Thus, these results support a model in which SuSy exists in a complex with the beta-glucan synthases and serves to channel carbon from sucrose to glucan. Images Fig. 1 Fig. 3 Fig. 4 PMID:7568131

  10. [Callose content in cell walls of leaf epidermis and mesophyll in Alisma plantago-aquatica L. plants growing in different conditions of water supply].

    PubMed

    Ovruts'ka, I I

    2014-01-01

    The relative callose content in Alisma plantago-aquatica leaves has been studied at the phases of budding and flowering--fruiting. The callose content in cell walls was shown to vary depending on the type of tissue, phase of ontogenesis and of water supply.

  11. Endosidin 7 Specifically Arrests Late Cytokinesis and Inhibits Callose Biosynthesis, Revealing Distinct Trafficking Events during Cell Plate Maturation.

    PubMed

    Park, Eunsook; Díaz-Moreno, Sara M; Davis, Destiny J; Wilkop, Thomas E; Bulone, Vincent; Drakakaki, Georgia

    2014-05-23

    Although cytokinesis is vital for plant growth and development, our mechanistic understanding of the highly regulated membrane and cargo transport mechanisms in relation to polysaccharide deposition during this process is limited. Here, we present an in-depth characterization of the small molecule endosidin 7 (ES7) inhibiting callose synthase activity and arresting late cytokinesis both in vitro and in vivo in Arabidopsis (Arabidopsis thaliana). ES7 is a specific inhibitor for plant callose deposition during cytokinesis that does not affect endomembrane trafficking during interphase or cytoskeletal organization. The specificity of ES7 was demonstrated (1) by comparing its action with that of known inhibitors such as caffeine, flufenacet, and concanamycin A and (2) across kingdoms with a comparison in yeast. The interplay between cell plate-specific post-Golgi vesicle traffic and callose accumulation was analyzed using ES7, and it revealed unique and temporal contributions of secretory and endosomal vesicles in cell plate maturation. While RABA2A-labeled vesicles, which accumulate at the early stage of cell plate formation, were not affected by ES7, KNOLLE was differentially altered by the small molecule. In addition, the presence of clathrin-coated vesicles in cells containing elevated levels of callose and their reduction under ES7 treatment further support the role of endocytic membrane remodeling in the maturing cell plate while the plate is stabilized by callose. Taken together, these data show the essential role of callose during the late stages of cell plate maturation and establish the temporal relationship between vesicles and regulatory proteins at the cell plate assembly matrix during polysaccharide deposition.

  12. Arabidopsis callose synthases CalS1/8 regulate plasmodesmal permeability during stress.

    PubMed

    Cui, Weier; Lee, Jung-Youn

    2016-01-01

    Plants need to cope with biotic and abiotic stress through well-coordinated cell-to-cell communication to survive as sedentary organisms. Environmental challenges such as wounding, low temperature, oxidative states and pathogen infection are known to affect the symplasmic molecular exchange between plant cells determined by plasmodesmal permeability. However, the signalling pathways and mechanisms by which different environmental stressors affect plasmodesmal permeability are not well understood. Here we show that regulating callose accumulation at plasmodesmal channels is a common strategy to alter plasmodesmal permeability under both pathogen infection and mechanical wounding stress. We have identified Arabidopsis callose synthase 1 (CalS1) and CalS8 as key genes involved in this process, and have integrated these new players into both known and novel signalling pathways that control responses to biotic and abiotic stress. Our studies provide experimental data that indicate the presence of specialized pathways tuned to respond to particular stressors, and new insights into how plants regulate plasmodesmata in response to environmental assaults. PMID:27243643

  13. Efferent limb of gastrojejunostomy obstruction by a whole okra phytobezoar: Case report and brief review

    PubMed Central

    Zin, Thant; Maw, Myat; Pai, Dinker Ramananda; Paijan, Rosaini Binti; Kyi, Myo

    2012-01-01

    A phytobezoar is one of the intraluminal causes of gastric outlet obstruction, especially in patients with previous gastric surgery and/or gastric motility disorders. Before the proton pump inhibitor era, vagotomy, pyloroplasty, gastrectomy and gastrojejunostomy were commonly performed procedures in peptic ulcer patients. One of the sequelae of gastrojejunostomy is phytobezoar formation. However, a bezoar causing gastric outlet obstruction is rare even with giant gastric bezoars. We report a rare case of gastric outlet obstruction due to a phytobezoar obstructing the efferent limb of the gastrojejunostomy site. This phytobezoar which consisted of a whole piece of okra (lady finger vegetable) was successfully removed by endoscopic snare. To the best of our knowledge, this is the first case of okra bezoar-related gastrojejunostomy efferent limb obstruction reported in the literature. PMID:22624073

  14. [The cervical somatosensory evoked potential in lesions of the cortical efferents].

    PubMed

    Strenge, H

    1990-03-01

    Cervical and cortical somatosensory evoked potentials to median nerve stimulation were analysed in 20 patients with unilateral central paresis of the arm. Neither the configuration nor the latency and amplitude measures of the neck potential did reveal any association with pathological alterations of cortical efferents or with abnormal cortically evoked responses. Thus, also in this population the evaluation of cervical potentials can be done according to the known criteria. PMID:2110891

  15. Origin of the primary efferent neurons projecting to the prostate of the dog.

    PubMed

    Zacharko, Anna; Arciszewski, Marcin Bartłomiej; Wasowicz, Krzysztof

    2004-08-01

    The retrograde tracing technique of neuronal tracer Fast Blue was used to determine sources of origin of efferent nerve fibers supplying the prostate of the dog. After injection of Fast Blue into the canine prostate retrogradely labelled neurons were found in bilateral L3-S3 sympathetic chain ganglia, bilateral caudal mesenteric ganglion and in bilateral pelvic plexus ganglia. No Fast Blue-positive neurons were present in bilateral L1-L2 sympathetic chain ganglia and in coeliac-mesenteric ganglion complex. The vast majority of Fast Blue-positive efferent prostate-projecting neurons (56.2% +/- 1.7) were located in bilateral caudal mesenteric ganglion, whereas 28.7% +/- 1.5 of them were located in bilateral pelvic plexus ganglia and 14.9% +/- 0.5 in bilateral L3-S3 sympathetic chain ganglia. Immunohistochemical staining for tyrosine hydroxylase and dopamine beta-hydroxylase was applied to determine the neurochemical character of Fast Blue-positive efferent neurons. Immunohistochemistry revealed that in all tyrosine hydroxylase immunoreactive Fast Blue-positive neurons immunoreactivity for dopamine beta-hydroxylase was also found (noradrenergic neurons) while all tyrosine hydroxylase-negative Fast Blue-positive neurons did not express dopamine beta-hydroxylase (non-noradrenergic neurons). In bilateral sympathetic chain ganglia, 96.4% +/- 2.1 of the prostate-projecting neurons were adrenergic and in bilateral caudal mesenteric ganglion this frequency amounted to 95.6% +/- 1.6. In bilateral pelvic plexus ganglia, 26.7% +/- 1.5 of the prostate-supplying efferent neurons did not express either tyrosine hydroxylase or dopamine beta-hydroxylase immunoreactivity which makes discussion of their cholinergic character possible. PMID:15481842

  16. The role of the renal afferent and efferent nerve fibers in heart failure

    PubMed Central

    Booth, Lindsea C.; May, Clive N.; Yao, Song T.

    2015-01-01

    Renal nerves contain afferent, sensory and efferent, sympathetic nerve fibers. In heart failure (HF) there is an increase in renal sympathetic nerve activity (RSNA), which can lead to renal vasoconstriction, increased renin release and sodium retention. These changes are thought to contribute to renal dysfunction, which is predictive of poor outcome in patients with HF. In contrast, the role of the renal afferent nerves remains largely unexplored in HF. This is somewhat surprising as there are multiple triggers in HF that have the potential to increase afferent nerve activity, including increased venous pressure and reduced kidney perfusion. Some of the few studies investigating renal afferents in HF have suggested that at least the sympatho-inhibitory reno-renal reflex is blunted. In experimentally induced HF, renal denervation, both surgical and catheter-based, has been associated with some improvements in renal and cardiac function. It remains unknown whether the effects are due to removal of the efferent renal nerve fibers or afferent renal nerve fibers, or a combination of both. Here, we review the effects of HF on renal efferent and afferent nerve function and critically assess the latest evidence supporting renal denervation as a potential treatment in HF. PMID:26483699

  17. The renal nerves in chronic heart failure: efferent and afferent mechanisms

    PubMed Central

    Schiller, Alicia M.; Pellegrino, Peter R.; Zucker, Irving H.

    2015-01-01

    The function of the renal nerves has been an area of scientific and medical interest for many years. The recent advent of a minimally invasive catheter-based method of renal denervation has renewed excitement in understanding the afferent and efferent actions of the renal nerves in multiple diseases. While hypertension has been the focus of much this work, less attention has been given to the role of the renal nerves in the development of chronic heart failure (CHF). Recent studies from our laboratory and those of others implicate an essential role for the renal nerves in the development and progression of CHF. Using a rabbit tachycardia model of CHF and surgical unilateral renal denervation, we provide evidence for both renal efferent and afferent mechanisms in the pathogenesis of CHF. Renal denervation prevented the decrease in renal blood flow observed in CHF while also preventing increases in Angiotensin-II receptor protein in the microvasculature of the renal cortex. Renal denervation in CHF also reduced physiological markers of autonomic dysfunction including an improvement in arterial baroreflex function, heart rate variability, and decreased resting cardiac sympathetic tone. Taken together, the renal sympathetic nerves are necessary in the pathogenesis of CHF via both efferent and afferent mechanisms. Additional investigation is warranted to fully understand the role of these nerves and their role as a therapeutic target in CHF. PMID:26300788

  18. Sound-evoked efferent effects on cochlear mechanics of the mustached bat.

    PubMed

    Drexl, Markus; Kössl, Manfred

    2003-10-01

    The influence of the crossed medial efferent system on cochlear mechanics of the mustached bat was tested by measuring delayed evoked otoacoustic emissions (DEOAEs), cochlear microphonics, distortion product otoacoustic emissions (DPOAEs) and stimulus frequency otoacoustic emissions. Contralaterally delivered sinusoids, broadband noise and bat echolocation calls were used for acoustic stimulation of the efferent system. With all four measures we found a level-dependent suppression under stimulation with both broadband noise and echolocation calls. In addition, the sharply tuned cochlear resonance of the mustached bat which is involved in processing echolocation signals at 61 kHz shifted upward in frequency by several 100 Hz. Presentation of sinusoids did not have any significant effect. DEOAEs and DPOAEs were in some cases enhanced during contralateral presentation of the bat calls at moderate intensities. The most important function of the efferent system in the mustached bat might be the control of the extraordinarily fine-tuned resonator of this species, which is close to instability as evident from the very pronounced evoked otoacoustic emissions which sometimes convert into spontaneous otoacoustic emissions of high level. PMID:14553904

  19. Relation between measures of speech-in-noise performance and measures of efferent activity

    NASA Astrophysics Data System (ADS)

    Smith, Brad; Harkrider, Ashley; Burchfield, Samuel; Nabelek, Anna

    2003-04-01

    Individual differences in auditory perceptual abilities in noise are well documented but the factors causing such variability are unclear. The purpose of this study was to determine if individual differences in responses measured from the auditory efferent system were correlated to individual variations in speech-in-noise performance. The relation between behavioral performance on three speech-in-noise tasks and two objective measures of the efferent auditory system were examined in thirty normal-hearing, young adults. Two of the speech-in-noise tasks measured an acceptable noise level, the maximum level of speech-babble noise that a subject is willing to accept while listening to a story. For these, the acceptable noise level was evaluated using both an ipsilateral (story and noise in same ear) and a contralateral (story and noise in opposite ears) paradigm. The third speech-in-noise task evaluated speech recognition using monosyllabic words presented in competing speech babble. Auditory efferent activity was assessed by examining the resulting suppression of click-evoked otoacoustic emissions following the introduction of a contralateral, broad-band stimulus and the activity of the ipsilateral and contralateral acoustic reflex arc was evaluated using tones and broad-band noise. Results will be discussed relative to current theories of speech in noise performance and auditory inhibitory processes.

  20. A High-Salt Diet Differentially Modulates Mechanical Activity of Afferent and Efferent Collecting Lymphatics in Murine Iliac Lymph Nodes

    PubMed Central

    Mizuno, Risuke; Ono, Nobuyuki; Nishimoto, Mitsuhiro; Fujita, Toshiro

    2015-01-01

    Abstract Background: The lymphatic system contributes to fluid homeostasis in various tissues. Recent evidence suggests that lymphangiogenesis induced by a high-salt diet (HSD) is associated with blood pressure regulation. Lymph nodes, located along lymphatic pathways, are not only important secondary lymphoid tissues for cancer metastasis, inflammation, and immune responses, but are also important for fluid homeostasis. Afferent lymphatics collect lymph from the pre-nodal area and efferent lymphatics drain lymph out of the lymph nodes. However, the difference in mechanical activity between afferent and efferent lymphatics and the effect of a HSD on these vessels have not been shown. Methods and Results: Changes in mechanical activity of isolated afferent and efferent lymphatics in normal salt diet (NSD) and 4-week HSD mice in response to increases in intraluminal pressures from 3 to 7 cmH2O were measured using video-microscopy. The higher intramural pressure equivalently decreased pumping activity of afferent and efferent lymphatics in NSD mice. A HSD suppressed the amplitude, ejection fraction, and stroke volume of afferent lymphatics, leading to marked reductions in pumping activity. In contrast, the pumping activities of efferent lymphatics were resistant to a HSD and were preserved by enhancing the contraction frequency. Conclusions: A HSD differentially modulated the mechanical activity of afferent and efferent collecting lymphatics in murine iliac lymph nodes. PMID:26091404

  1. Intermittent alien hand syndrome and callosal apraxia in multiple sclerosis: implications for interhemispheric communication.

    PubMed

    Lunardelli, A; Sartori, A; Mengotti, P; Rumiati, R I; Pesavento, V

    2014-01-01

    We report a case of a 47-year-old woman with 35-year history of multiple sclerosis, who showed alien hand signs, a rare behavioural disorder that involves unilateral goal-directed movements that are contrary to the individual's intention. Alien hand syndrome has been described in multiple sclerosis (MS) only occasionally and is generally suggestive of callosal disconnection. The patient presented also with bilateral limb apraxia and left hand agraphia, raising the possibility of cortical dysfunction or disconnection, in addition to corpus callosum and white matter involvement. Her specific pattern of symptoms supports the role of the corpus callosum in interhemispheric communication for complex as well as fine motor activities and may indicate that it can serve as both an inhibitory and excitatory function depending on task demands. PMID:24803736

  2. Disruption of estrogen receptor signaling and similar pathways in the efferent ductules and initial segment of the epididymis

    PubMed Central

    Hess, Rex A

    2014-01-01

    Abstract: Seminiferous tubular atrophy may involve indirectly the disruption of estrogen receptor-α (ESR1) function in efferent ductules of the testis. ESR1 helps to maintain fluid resorption by the ductal epithelium and the inhibition or stimulation of this activity in rodent species will lead to fluid accumulation in the lumen. If not resolved, the abnormal buildup of fluid in the head of the epididymis and efferent ductules becomes a serious problem for the testis, as it leads to an increase in testis weight, tubular dilation and seminiferous epithelial degeneration, as well as testicular atrophy. The same sequence of pathogenesis occurs if the efferent ductule lumen becomes occluded. This review provides an introduction to the role of estrogen in the male reproductive tract but focuses on the various overlapping mechanisms that could induce efferent ductule dysfunction and fluid backpressure histopathology. Although efferent ductules are difficult to find, their inclusion in routine histological evaluations is recommended, as morphological images of these delicate tubules may be essential for understanding the mechanism of testicular injury, especially if dilations are observed in the rete testis and/or seminiferous tubules. Signature Lesion: The rete testis and efferent ductules can appear dilated, as if the lumens were greatly expanded with excess fluid or the accumulation of sperm. Because the efferent ductules resorb most of the fluid arriving from the rete testis lumen, one of two mechanisms is likely to be involved: a) reduced fluid uptake, which has been caused by the disruption in estrogen receptor signaling or associated pathways; or b) an increased rate of fluid resorption, which results in luminal occlusion. Both mechanisms can lead to a temporary increase in testicular weight, tubular dilation and atrophy of the seminiferous tubules. PMID:26413389

  3. Efferent Vestibular Neurons Show Homogenous Discharge Output But Heterogeneous Synaptic Input Profile In Vitro

    PubMed Central

    Mathews, Miranda A.; Murray, Andrew; Wijesinghe, Rajiv; Cullen, Karen; Tung, Victoria W. K.; Camp, Aaron J.

    2015-01-01

    Despite the importance of our sense of balance we still know remarkably little about the central control of the peripheral balance system. While previous work has shown that activation of the efferent vestibular system results in modulation of afferent vestibular neuron discharge, the intrinsic and synaptic properties of efferent neurons themselves are largely unknown. Here we substantiate the location of the efferent vestibular nucleus (EVN) in the mouse, before characterizing the input and output properties of EVN neurons in vitro. We made transverse serial sections through the brainstem of 4-week-old mice, and performed immunohistochemistry for calcitonin gene-related peptide (CGRP) and choline acetyltransferase (ChAT), both expressed in the EVN of other species. We also injected fluorogold into the posterior canal and retrogradely labelled neurons in the EVN of ChAT:: tdTomato mice expressing tdTomato in all cholinergic neurons. As expected the EVN lies dorsolateral to the genu of the facial nerve (CNVII). We then made whole-cell current-, and voltage-clamp recordings from visually identified EVN neurons. In current-clamp, EVN neurons display a homogeneous discharge pattern. This is characterized by a high frequency burst of action potentials at the onset of a depolarizing stimulus and the offset of a hyperpolarizing stimulus that is mediated by T-type calcium channels. In voltage-clamp, EVN neurons receive either exclusively excitatory or inhibitory inputs, or a combination of both. Despite this heterogeneous mixture of inputs, we show that synaptic inputs onto EVN neurons are predominantly excitatory. Together these findings suggest that the inputs onto EVN neurons, and more specifically the origin of these inputs may underlie EVN neuron function. PMID:26422206

  4. Effects of adenosine receptor agonists on efferent renal nerve activity in anesthetized rats.

    PubMed

    Genovesi, S; Pieruzzi, F; Camisasca, P; Ragonesi, G; Protasoni, G; Golin, R; Zanchetti, A; Stella, A

    2000-02-01

    The aim of this study was to investigate the effects of A1 and A2 adenosine-receptor activation on the sympathetic nervous system. The effects on efferent renal nerve activity of selective A1 (CCPA; 2-chloro-N-6-cyclopentyladenosine) and A2 (2HE-NECA; 2-hexynyl-5'-N-ethylcarboxamidoadenosine) adenosine-receptor agonists were studied in anesthetized rats either with intact baroreflexes (intact rats) or with bilateral sinoaortic denervation and vagotomy (denervated rats). After a control period of 5 min, A1 or A2 agonist or vehicle were intravenously infused for 8 min in separate groups of intact or denervated rats, in which arterial pressure and heart rate were continuously recorded. CCPA (5.0 microg/kg/min) and 2HE-NECA (0.7 microg/kg/min) were selected to obtain comparable blood pressure changes over the period of observation. Arterial pressure significantly and equally decreased during the A1 (-41 +/- 8%), and A2 (-35 +/- 5%) agonist administration. Heart rate significantly decreased during A1 agonist infusion, but it did not change during A2 agonist administration. Bilateral sinoaortic denervation and vagotomy did not modify the hemodynamic responses to both drugs. The A1 and A2 administration caused a large and significant increase in efferent renal nerve activity (+66 +/- 22% and +76 +/- 15%, respectively), and this effect was entirely abolished in denervated rats. A linear relation with a significant negative slope between changes in arterial pressure and changes in neural discharge was observed for each treatment. The comparison of the regression slopes showed that the reflex increase of efferent sympathetic activity caused by the administration of both agonists was significantly smaller than the increment induced by equipotent hypotensive dose of sodium nitroprusside (10 microg/kg). These data show that the selective activation of A1 and A2 receptors elicits a reflex increase in efferent renal nerve activity. This neural activation is smaller as compared

  5. Oculomotor learning revisited: a model of reinforcement learning in the basal ganglia incorporating an efference copy of motor actions

    PubMed Central

    Fee, Michale S.

    2012-01-01

    In its simplest formulation, reinforcement learning is based on the idea that if an action taken in a particular context is followed by a favorable outcome, then, in the same context, the tendency to produce that action should be strengthened, or reinforced. While reinforcement learning forms the basis of many current theories of basal ganglia (BG) function, these models do not incorporate distinct computational roles for signals that convey context, and those that convey what action an animal takes. Recent experiments in the songbird suggest that vocal-related BG circuitry receives two functionally distinct excitatory inputs. One input is from a cortical region that carries context information about the current “time” in the motor sequence. The other is an efference copy of motor commands from a separate cortical brain region that generates vocal variability during learning. Based on these findings, I propose here a general model of vertebrate BG function that combines context information with a distinct motor efference copy signal. The signals are integrated by a learning rule in which efference copy inputs gate the potentiation of context inputs (but not efference copy inputs) onto medium spiny neurons in response to a rewarded action. The hypothesis is described in terms of a circuit that implements the learning of visually guided saccades. The model makes testable predictions about the anatomical and functional properties of hypothesized context and efference copy inputs to the striatum from both thalamic and cortical sources. PMID:22754501

  6. How can the auditory efferent system protect our ears from noise-induced hearing loss? Let us count the ways

    NASA Astrophysics Data System (ADS)

    Marshall, Lynne; Miller, Judi A. Lapsley

    2015-12-01

    It is a cause for some debate as to how the auditory olivocochlear (OC) efferent system could protect hearing from noise trauma. In this review, we examined physiological research to find mechanisms that could effectively attenuate the response to sound. For each purported mechanism, we indicate which part of the OC-efferent system is responsible for the function and the site of action. These mechanisms include basilar-membrane phase shifts at high stimulus levels; changes in outer-hair-cell stiffness and phase lag associated with efferent slow effects; small decreases in endocochlear potentials causing small decreases in outer- and inner-hair-cell output; low-spontaneous-rate and medium-spontaneous-rate fibers showing OC-induced decrements at high levels; auditory-nerve initial-peak reduction; OC effect increasing over minutes; cholinergic activation of anti-apoptotic pathways; and anti-excitotoxicity. There are clearly multiple opportunities for the OC-efferent system to protect the inner ear from noise trauma. From further exploration into the mechanisms outlined here, as well as to-be-discovered mechanisms, we will gain a greater understanding of the protective nature of the OC-efferent system. These findings could aid our ability to design better predictive tests for people at risk for noise-induced hearing loss.

  7. An electrophysiological study of single vagal efferent units associated with gastric movements in sheep

    PubMed Central

    Iggo, A.; Leek, B. F.

    1967-01-01

    1. A method for obtaining reticulo-ruminal movements for up to 19 hr in halothane-anaesthetized sheep is described. The duration, wave form and frequency of the movements resembles those in the conscious animal except that ruminal movements have a lower amplitude. 2. A method of recording for up to 5½ hr single efferent unit discharges from fibres presumed to innervate the reticulo-rumen is described. 3. At least seven distinguishable types of discharge pattern were recorded. By relating these temporally to movements of the reticulum and rumen it was concluded that Types I, II and III occurred in fibres innervating the reticulum or associated structures, Type IV the rumen and Types V, VI and VII other gastric structures not yet identified. Apart from Type VII units there was no `resting discharge' in efferent fibres during the quiescent phase of the gastric cycle. 4. We conclude that the co-ordination of the complex sequence of gastric movements in ruminant animals is a function of the `gastric centres' in the hind-brain through their ability to determine the pattern, durations, spike frequencies and temporal interrelationships of discharges in gastric motoneurons innervating the different parts of the forestomach. PMID:6050614

  8. The contribution of late-generated neurons to the callosal projection in rat: a study with prenatal x-irradiation

    SciTech Connect

    Jensen, K.F.; Altman, J.

    1982-08-01

    Studies utilizing horseradish peroxidase tracing methods have suggested that there are species differences in the relative contribution of the different neocortical layers to the callosal projection. The present investigation utilized x-irradiation at different gestational ages to eliminate the late-generated neurons in the rat neocortex. The caudorostral gradient of reduction in the neuronal population of the supragranular layers is closely correlated with the gradient of reduction in the size of the corpus callosum. Furthermore, the callosal projection is absent in anteroposterior cortical segments in which the development of the supragranular layers was prevented without a reduction of the number of neurons in the infragranular layers of the neocortex. These results indicate that late-generated neurons residing primarily in the supragranular layers are essential for the formation of the corpus callosum.

  9. Dissociation between distal and proximal left limb agraphia and agraphesthesia in a patient with a callosal disconnection syndrome.

    PubMed

    Bachoud-Lévi, A C; Ergis, A M; Cesaro, P; Degos, J D

    2000-06-01

    A few neuropsychological studies have suggested the existence of bilateral hemispheric representations for the proximal parts of the limbs in humans. We report the case of a patient who presented with a callosal disconnection syndrome, which at a later stage of disease became restricted to left agraphia, left agraphesthesia and left auditory extinction. The anomic character of the agraphesthesia was demonstrated. Tactile naming was normal, which allows us to conclude that separate callosal pathways related to the left language areas transmit information for graphesthesia and tactile naming. Agraphia and agraphesthesia were not observed when the proximal part of the left upper limb was utilized. These observations support the conclusion that writing and graphesthesia with the proximal part of the limb can be mediated by the ipsilateral cortex.

  10. Transgenic Arabidopsis thaliana plants expressing a β-1,3-glucanase from sweet sorghum (Sorghum bicolor L.) show reduced callose deposition and increased tolerance to aluminium toxicity.

    PubMed

    Zhang, Hui; Shi, Wu Liang; You, Jiang Feng; Bian, Ming Di; Qin, Xiao Mei; Yu, Hui; Liu, Qing; Ryan, Peter R; Yang, Zhen Ming

    2015-06-01

    Seventy-one cultivars of sweet sorghum (Sorghum bicolor L.) were screened for aluminium (Al) tolerance by measuring relative root growth (RRG). Two contrasting cultivars, ROMA (Al tolerant) and POTCHETSTRM (Al sensitive), were selected to study shorter term responses to Al stress. POTCHETSTRM had higher callose synthase activity, lower β-1,3-glucanase activity and more callose deposition in the root apices during Al treatment compared with ROMA. We monitored the expression of 12 genes involved in callose synthesis and degradation and found that one of these, SbGlu1 (Sb03g045630.1), which encodes a β-1,3-glucanase enzyme, best explained the contrasting deposition of callose in ROMA and POTCHETSTRM during Al treatment. Full-length cDNAs of SbGlu1 was prepared from ROMA and POTCHETSTRM and expressed in Arabidopsis thaliana using the constitutive cauliflower mosaic virus (CaMV) 35S promoter. Independent transgenic lines displayed significantly greater Al tolerance than wild-type plants and vector-only controls. This phenotype was associated with greater total β-1,3-glucanase activity, less Al accumulation and reduced callose deposition in the roots. These results suggest that callose production is not just an early indicator of Al stress in plants but likely to be part of the toxicity pathway that leads to the inhibition of root growth.

  11. Aniline blue and Calcofluor white staining of callose and cellulose in the streptophyte green algae Zygnema and Klebsormidium

    PubMed Central

    Herburger, Klaus; Holzinger, Andreas

    2016-01-01

    Plant including green algal cells are surrounded by a cell wall, which is a diverse composite of complex polysaccharides and crucial for their function and survival. Here we describe two simple protocols to visualize callose (β-1→3-glucan) and cellulose (β-1→4-glucan) and related polysaccharides in the cell walls of streptophyte green algae by using standard dyes and epifluorescence microscopy. PMID:27785458

  12. Complete callosal agenesis, pontocerebellar hypoplasia, and axonal neuropathy due to AMPD2 loss

    PubMed Central

    Marsh, Ashley P.L.; Lukic, Vesna; Pope, Kate; Bromhead, Catherine; Tankard, Rick; Ryan, Monique M.; Yiu, Eppie M.; Sim, Joe C.H.; Delatycki, Martin B.; Amor, David J.; McGillivray, George; Sherr, Elliott H.; Bahlo, Melanie; Leventer, Richard J.

    2015-01-01

    Objective: To determine the molecular basis of a severe neurologic disorder in a large consanguineous family with complete agenesis of the corpus callosum (ACC), pontocerebellar hypoplasia (PCH), and peripheral axonal neuropathy. Methods: Assessment included clinical evaluation, neuroimaging, and nerve conduction studies (NCSs). Linkage analysis used genotypes from 7 family members, and the exome of 3 affected siblings was sequenced. Molecular analyses used Sanger sequencing to perform segregation studies and cohort analysis and Western blot of patient-derived cells. Results: Affected family members presented with postnatal microcephaly and profound developmental delay, with early death in 3. Neuroimaging, including a fetal MRI at 30 weeks, showed complete ACC and PCH. Clinical evaluation showed areflexia, and NCSs revealed a severe axonal neuropathy in the 2 individuals available for electrophysiologic study. A novel homozygous stopgain mutation in adenosine monophosphate deaminase 2 (AMPD2) was identified within the linkage region on chromosome 1. Molecular analyses confirmed that the mutation segregated with disease and resulted in the loss of AMPD2. Subsequent screening of a cohort of 42 unrelated individuals with related imaging phenotypes did not reveal additional AMPD2 mutations. Conclusions: We describe a family with a novel stopgain mutation in AMPD2. We expand the phenotype recently described as PCH type 9 to include progressive postnatal microcephaly, complete ACC, and peripheral axonal neuropathy. Screening of additional individuals with related imaging phenotypes failed to identify mutations in AMPD2, suggesting that AMPD2 mutations are not a common cause of combined callosal and pontocerebellar defects. PMID:27066553

  13. Rotational head trauma with callosal contusion and C6 fracture: a high-speed motorcycle accident.

    PubMed

    Vyshka, Gentian; Troshani, Blerti; Bozaxhiu, Dorjan; Mitrushi, Arben

    2013-01-01

    We present the case of a 34-year-old Albanian male who was riding a motorcycle when he collided at high-speed with a four-wheel vehicle. After a triple pivotal rotation in the air at the moment of impact, he fell from the motorcycle to the ground. The clinical picture thereafter was one of deep coma, treated in the intensive care unit for nine days, until he regained consciousness and long-term rehabilitation procedures were put in place. The magnetic resonance and computed tomography images were very illustrative of a rotational head trauma mechanism, since in addition to multiple callosal hemorrhages and the lack of cranial fractures, a linear complex fracture of the C6 vertebra was seen, justifying orthopedic treatment through immobilization of the cervical spine. Rotational angular acceleration seems to be an important causative factor toward provoking diffuse brain and/or axonal injury; the etiological importance on the direct skull impact is controversial, but in any case not negligible. PMID:23588986

  14. Mid-callosal plane determination using preferred directions from diffusion tensor images

    NASA Astrophysics Data System (ADS)

    Costa, André L.; Rittner, Letícia; Lotufo, Roberto A.; Appenzeller, Simone

    2015-03-01

    The corpus callosum is the major brain structure responsible for inter{hemispheric communication between neurons. Many studies seek to relate corpus callosum attributes to patient characteristics, cerebral diseases and psychological disorders. Most of those studies rely on 2D analysis of the corpus callosum in the mid-sagittal plane. However, it is common to find conflicting results among studies, once many ignore methodological issues and define the mid-sagittal plane based on precary or invalid criteria with respect to the corpus callosum. In this work we propose a novel method to determine the mid-callosal plane using the corpus callosum internal preferred diffusion directions obtained from diffusion tensor images. This plane is analogous to the mid-sagittal plane, but intended to serve exclusively as the corpus callosum reference. Our method elucidates the great potential the directional information of the corpus callosum fibers have to indicate its own referential. Results from experiments with five image pairs from distinct subjects, obtained under the same conditions, demonstrate the method effectiveness to find the corpus callosum symmetric axis relative to the axial plane.

  15. Distinct roles of neuropilin 1 signaling for radial and tangential extension of callosal axons.

    PubMed

    Hatanaka, Yumiko; Matsumoto, Tomoko; Yanagawa, Yuchio; Fujisawa, Hajime; Murakami, Fujio; Masu, Masayuki

    2009-05-20

    Cortical excitatory neurons migrate from their origin in the ventricular zone (VZ) toward the pial surface. During migration, these neurons exhibit a stellate shape in the intermediate zone (IZ), transform into bipolar cells, and then initiate radial migration, extending a trailing process, which may lead to an axon. Here we examined the role of neuropilin 1 (NRP1) in these developmental events. Both NRP1 mRNA and protein were highly expressed in the IZ, where stellate-shaped cells were located. DiI labeling experiments showed that neuronal migration occurred normally in Nrp1 mutant mice up to embryonic day (E) 14.5, the latest day to which the mutant survives, with only subtle axonal defasciculation. However, interference with Nrp1 signaling at a later stage caused pathfinding errors: when a dominant negative form of Nrp1 was electroporated into the cortical VZ cells at E12.5 or E15.5 and examined perinatally, guidance errors were found in tangential axonal extension toward the midline. In contrast, no significant effect was noted on the migration of cortical excitatory neurons. These findings indicate that NRP1 plays an important role in the guidance of callosal axons originating from cortical excitatory neurons but does not support a role in their migration. Moreover, insofar as radial axonal extension within the cortical plate was unaffected, the present findings imply that molecular mechanisms for the axonal extension of excitatory neurons within the cortical plate are distinct from those in the white matter. PMID:19296474

  16. Physiological Characterization of Vestibular Efferent Brainstem Neurons Using a Transgenic Mouse Model

    PubMed Central

    Leijon, Sara; Magnusson, Anna K.

    2014-01-01

    The functional role of efferent innervation of the vestibular end-organs in the inner ear remains elusive. This study provides the first physiological characterization of the cholinergic vestibular efferent (VE) neurons in the brainstem by utilizing a transgenic mouse model, expressing eGFP under a choline-acetyltransferase (ChAT)-locus spanning promoter in combination with targeted patch clamp recordings. The intrinsic electrical properties of the eGFP-positive VE neurons were compared to the properties of the lateral olivocochlear (LOC) brainstem neurons, which gives rise to efferent innervation of the cochlea. Both VE and the LOC neurons were marked by their negative resting membrane potential <−75 mV and their passive responses in the hyperpolarizing range. In contrast, the response properties of VE and LOC neurons differed significantly in the depolarizing range. When injected with positive currents, VE neurons fired action potentials faithfully to the onset of depolarization followed by sparse firing with long inter-spike intervals. This response gave rise to a low response gain. The LOC neurons, conversely, responded with a characteristic delayed tonic firing upon depolarizing stimuli, giving rise to higher response gain than the VE neurons. Depolarization triggered large TEA insensitive outward currents with fast inactivation kinetics, indicating A-type potassium currents, in both the inner ear-projecting neuronal types. Immunohistochemistry confirmed expression of Kv4.3 and 4.2 ion channel subunits in both the VE and LOC neurons. The difference in spiking responses to depolarization is related to a two-fold impact of these transient outward currents on somatic integration in the LOC neurons compared to in VE neurons. It is speculated that the physiological properties of the VE neurons might be compatible with a wide-spread control over motion and gravity sensation in the inner ear, providing likewise feed-back amplification of abrupt and strong phasic

  17. The role of resting frontal EEG asymmetry in psychopathology: afferent or efferent filter?

    PubMed

    Gatzke-Kopp, Lisa M; Jetha, Michelle K; Segalowitz, Sidney J

    2014-01-01

    Resting EEG asymmetry evident early in life is thought to bias affective behaviors and contribute to the development of psychopathology. However, it remains unclear at what stage of information processing this bias occurs. Asymmetry may serve as an afferent filter, modulating emotional reactivity to incoming stimuli; or as an efferent filter, modulating behavioral response tendencies under emotional conditions. This study examines 209 kindergarten children (M = 6.03 years old) to test predictions put forth by the two models. Resting asymmetry was examined in conjunction with electrodermal and cardiac measures of physiological reactivity to four emotion-inducing film clips (fear, sad, happy, anger) and teacher ratings of psychopathology. Results confirm an association between increased right side cortical activation and internalizing symptom severity as well as left activation and externalizing symptom severity. Significant interactions between resting asymmetry and physiological reactivity to emotion indicate that physiological reactivity moderates the association between resting asymmetry and symptoms of psychopathology.

  18. Primary motor cortex reports efferent control of vibrissa motion on multiple time scales

    PubMed Central

    Hill, Daniel N.; Curtis, John C.; Moore, Jeffrey D.; Kleinfeld, David

    2011-01-01

    Exploratory whisking in rat is an example of self-generated movement on multiple time scales, from slow variations in the envelope of whisking to the rapid sequence of muscle contractions during a single whisk cycle. We find that, as a population, spike trains of single units in primary vibrissa motor cortex report the absolute angle of vibrissa position. This representation persists after sensory nerve transection, indicating an efferent source. About two-thirds of the units are modulated by slow variations in the envelope of whisking while relatively few units report rapid changes in position within the whisk cycle. The combined results from this study and past measurements, which show that primary sensory cortex codes the whisking envelope as a motor copy signal, imply that signals present in both sensory and motor cortices are necessary to compute coordinates based on vibrissa touch. PMID:22017992

  19. Rapid Enrichment of CHAPS-Solubilized UDP-Glucose: (1,3)-β-Glucan (Callose) Synthase from Beta vulgaris L. by Product Entrapment 1

    PubMed Central

    Wu, Ayong; Harriman, Robert W.; Frost, David J.; Read, Stephen M.; Wasserman, Bruce P.

    1991-01-01

    Rapid enrichment of CHAPS-solubilized UDP-glucose:(1,3)-β-glucan (callose) synthase from storage tissue of red beet (Beta vulgaris L.) is obtained when the preparation is incubated with an enzyme assay mixture, then centrifuged and the enzyme released from the callose pellet with a buffer containing EDTA and CHAPS (20-fold purification relative to microsomes). When centrifuged at high speed (80,000g), the enzyme can also be pelleted in the absence of substrate (UDP-Glc) or synthesis of callose, due to nonspecific aggregation of proteins caused by excess cations and insufficient detergent in the assay buffer. True time-dependent and substrate-dependent product-entrapment of callose synthase is obtained by low-speed centrifugation (7,000-11,000g) of enzyme incubated in reaction mixtures containing low levels of cations (0.5 millimolar Mg2+, 1 millimolar Ca2+) and sufficient detergent (0.02% digitonin, 0.12% CHAPS), together with cellobiose, buffer, and UDP-Glc. Entrapment conditions, therefore, are a compromise between preventing nonspecific precipitation of proteins and permitting sufficient enzyme activity for callose synthesis. Further enrichment of the enzyme released from the callose pellet was not obtained by rate-zonal glycerol gradient centrifugation, although its sedimentation rate was greatly enhanced by inclusion of divalent cations in the gradient. Preparations were markedly cleaner when product-entrapment was conducted on enzyme solubilized from plasma membranes isolated by aqueous two-phase partitioning rather than by gradient centrifugation. Product-entrapped preparations consistently contained polypeptides or groups of closely-migrating polypeptides at molecular masses of 92, 83, 70, 57, 43, 35, 31/29, and 27 kilodaltons. This polypeptide profile is in accordance with the findings of other callose synthase enrichment studies using a variety of tissue sources, and is consistent with the existence of a multi-subunit enzyme complex. ImagesFigure 6Figure

  20. Spinal efference copy signaling and gaze stabilization during locomotion in juvenile Xenopus frogs.

    PubMed

    von Uckermann, Géraldine; Le Ray, Didier; Combes, Denis; Straka, Hans; Simmers, John

    2013-03-01

    In swimming Xenopus laevis tadpoles, gaze stabilization is achieved by efference copies of spinal locomotory CPG output that produce rhythmic extraocular motor activity appropriate for minimizing motion-derived visual disturbances. During metamorphosis, Xenopus switches its locomotory mechanism from larval tail-based undulatory movements to bilaterally synchronous hindlimb kick propulsion in the adult. The change in locomotory mode leads to body motion dynamics that no longer require conjugate left-right eye rotations for effective retinal image stabilization. Using in vivo kinematic analyses, in vitro electrophysiological recordings and specific CNS lesions, we have investigated spino-extraocular motor coupling in the juvenile frog and the underlying neural pathways to understand how gaze control processes are altered in accordance with the animal's change in body plan and locomotor strategy. Recordings of extraocular and limb motor nerves during spontaneous "fictive" swimming in isolated CNS preparations revealed that there is indeed a corresponding change in spinal efference copy control of extraocular motor output. In contrast to fictive larval swimming where alternating bursts occur in bilateral antagonistic horizontal extraocular nerves, during adult fictive limb-kicking, these motor nerves are synchronously active in accordance with the production of convergent eye movements during the linear head accelerations resulting from forward propulsion. Correspondingly, the neural pathways mediating spino-extraocular coupling have switched from contralateral to strictly ipsilateral ascending influences that ensure a coactivation of bilateral extraocular motoneurons with synchronous left-right limb extensions. Thus, adaptive developmental plasticity during metamorphosis enables spinal CPG-driven extraocular motor activity to match the changing requirements for eye movement control during self-motion.

  1. The Hyperactivity of Efferent Auditory System in Patients with Schizophrenia: A Transient Evoked Otoacoustic Emissions Study

    PubMed Central

    Wahab, Suzaily; Abdul Rahman, Abdul Hamid; Sidek, Dinsuhaimi; Zakaria, Mohd. Normani

    2016-01-01

    Objective Electrophysiological studies, which are mostly focused on afferent pathway, have proven that auditory processing deficits exist in patients with schizophrenia. Nevertheless, reports on the suppressive effect of efferent auditory pathway on cochlear outer hair cells among schizophrenia patients are limited. The present, case-control, study examined the contralateral suppression of transient evoked otoacoustic emissions (TEOAEs) in patients with schizophrenia. Methods Participants were twenty-three healthy controls and sixteen schizophrenia patients with normal hearing, middle ear and cochlear outer hair cells function. Absolute non-linear and linear TEOAEs were measured in both ears by delivering clicks stimuli at 80 dB SPL and 60 dB SPL respectively. Subsequently, contralateral suppression was determined by subtracting the absolute TEOAEs response obtained at 60 dBpe SPL during the absence and presence of contralateral white noise delivered at 65 dB HL. No attention tasks were conducted during measurements. Results We found no significant difference in absolute TEOAEs responses at 80 dB SPL, in either diagnosis or ear groups (p>0.05). However, the overall contralateral suppression was significantly larger in schizophrenia patients (p<0.05). Specifically, patients with schizophrenia demonstrated significantly increased right ear contralateral suppression compared to healthy control (p<0.05). Conclusion The present findings suggest increased inhibitory effect of efferent auditory pathway especially on the right cochlear outer hair cells. Further studies to investigate increased suppressive effects are crucial to expand the current understanding of auditory hallucination mechanisms in schizophrenia patients. PMID:26766950

  2. Language lateralization in individuals with callosal agenesis: an fMRI study.

    PubMed

    Pelletier, Isabelle; Paquette, Natacha; Lepore, Franco; Rouleau, Isabelle; Sauerwein, Catherine H; Rosa, Christine; Leroux, Jean-Maxime; Gravel, Pierre; Valois, Katja; Andermann, Frederick; Saint-Amour, Dave; Lassonde, Maryse

    2011-06-01

    Since the seminal work of Broca in 1861, it is well established that language is essentially processed in the left hemisphere. However, the origin of hemispheric specialization remains controversial. Some authors posit that language lateralization is genetically determined, while others have suggested that hemispheric specialization develops with age. Tenants of the latter view have further suggested that the adult pattern of left hemispheric specialization is achieved by means of callosal inhibition of homologous speech areas in the right hemisphere during ontogeny. According to this hypothesis, one would expect language to develop bilaterally in the acallosal brain. A recent functional magnetic resonance imaging (fMRI) study in one patient with agenesis of the corpus callosum suggests that this might indeed be the case (Riecker et al., 2007). However, given the large anatomic and functional variability in the population of subjects with agenesis of the corpus callosum, this finding needs to be more extensively replicated. In the present study, we explored language lateralization in six individuals with agenesis of the corpus callosum using an fMRI protocol which included a syntactic decision task and a sub-vocal verbal fluency task. Two neurologically intact control groups, one comparable to the acallosals in terms of IQ, age and education (n=6) and one group with a high IQ (n=5), performed the same tasks. No differences were found between language lateralization of the subjects with agenesis of the corpus callosum and the control groups in the receptive speech task. However, for expressive speech, the groups differed with respect to frontal activations, with the acallosal participants showing a more bilateral pattern of activation than the high-IQ participants only. No differences were found for temporal regions. Overall, these results indicate that the corpus callosum is not essential for the establishment of lateralized language functions. PMID:21447350

  3. [Acute disseminated encephalomyelitis following influenza vaccination: report of a case with callosal disconnection syndrome].

    PubMed

    Arai, Motomi; Takagi, Daisuke; Nagao, Ryosuke

    2014-01-01

    We present a case of callosal disconnection syndrome as a rare manifestation of acute disseminated encephalomyelitis (ADEM). A dextral 48-year-old Japanese woman received trivalent inactivated influenza vaccine in mid-November 2011. Twenty days later, she was found to be in a daze. Subsequently, she developed abnormal behavior and gait disturbance, and she was disoriented regarding time and place. Nystagmus and abnormal ocular movements were absent. Upper limb power was normal, whereas her lower limbs were mildly weak. Tendon reflexes were normally evoked without pathological reflexes. There was no sensory impairment. Serum CRP levels were slightly elevated; other routine laboratory tests, thyroid functions, and vitamin B1 levels were within the normal range. Cerebrospinal fluid examination revealed that it was acellular with a protein level of 54 mg/dl and high myelin basic protein level. Fluid-attenuated inversion recovery MR images revealed a large hyperintense lesion in the corpus callosum, but the lower part of the splenium was spared. Flow voids were observed in the pericallosal arteries. She was diagnosed with post-vaccination ADEM and vigorously treated with an intravenous infusion of methylprednisolone (1 g/day for 6 days) and immunoglobulin (1.2 g/kg). Gait disturbance and disorientation rapidly improved; however, tactile anomia, ideomotor apraxia, ideational apraxia, and agraphia of the left hand were present one month after onset. She had no aphasia or alexia.Interestingly, the patient's left unilateral agraphia was more prominent in kana than kanji (an article in Japanese text) for polysyllabic words, whereas she could write kana characters to dictation. Changes in the sequential order of kana characters within a word were observed. These findings were similar to those observed in pure agraphia associated with lesions in the posterior part of the left middle frontal gyrus. Thus, an interhemispheric mechanism is probably involved in the selection and

  4. Small RNA Derived from the Virulence Modulating Region of the Potato spindle tuber viroid Silences callose synthase Genes of Tomato Plants.

    PubMed

    Adkar-Purushothama, Charith Raj; Brosseau, Chantal; Giguère, Tamara; Sano, Teruo; Moffett, Peter; Perreault, Jean-Pierre

    2015-08-01

    The tomato (Solanum lycopersicum) callose synthase genes CalS11-like and CalS12-like encode proteins that are essential for the formation of callose, a major component of pollen mother cell walls; these enzymes also function in callose formation during pathogen infection. This article describes the targeting of these callose synthase mRNAs by a small RNA derived from the virulence modulating region of two Potato spindle tuber viroid variants. More specifically, viroid infection of tomato plants resulted in the suppression of the target mRNAs up to 1.5-fold, depending on the viroid variant used and the gene targeted. The targeting of these mRNAs by RNA silencing was validated by artificial microRNA experiments in a transient expression system and by RNA ligase-mediated rapid amplification of cDNA ends. Viroid mutants incapable of targeting callose synthase mRNAs failed to induce typical infection phenotypes, whereas a chimeric viroid obtained by swapping the virulence modulating regions of a mild and a severe variant of Potato spindle tuber viroid greatly affected the accumulation of viroids and the severity of disease symptoms. These data provide evidence of the silencing of multiple genes by a single small RNA derived from a viroid. PMID:26290537

  5. Small RNA Derived from the Virulence Modulating Region of the Potato spindle tuber viroid Silences callose synthase Genes of Tomato Plants.

    PubMed

    Adkar-Purushothama, Charith Raj; Brosseau, Chantal; Giguère, Tamara; Sano, Teruo; Moffett, Peter; Perreault, Jean-Pierre

    2015-08-01

    The tomato (Solanum lycopersicum) callose synthase genes CalS11-like and CalS12-like encode proteins that are essential for the formation of callose, a major component of pollen mother cell walls; these enzymes also function in callose formation during pathogen infection. This article describes the targeting of these callose synthase mRNAs by a small RNA derived from the virulence modulating region of two Potato spindle tuber viroid variants. More specifically, viroid infection of tomato plants resulted in the suppression of the target mRNAs up to 1.5-fold, depending on the viroid variant used and the gene targeted. The targeting of these mRNAs by RNA silencing was validated by artificial microRNA experiments in a transient expression system and by RNA ligase-mediated rapid amplification of cDNA ends. Viroid mutants incapable of targeting callose synthase mRNAs failed to induce typical infection phenotypes, whereas a chimeric viroid obtained by swapping the virulence modulating regions of a mild and a severe variant of Potato spindle tuber viroid greatly affected the accumulation of viroids and the severity of disease symptoms. These data provide evidence of the silencing of multiple genes by a single small RNA derived from a viroid.

  6. Small RNA Derived from the Virulence Modulating Region of the Potato spindle tuber viroid Silences callose synthase Genes of Tomato Plants[OPEN

    PubMed Central

    Adkar-Purushothama, Charith Raj; Brosseau, Chantal; Giguère, Tamara; Sano, Teruo; Moffett, Peter; Perreault, Jean-Pierre

    2015-01-01

    The tomato (Solanum lycopersicum) callose synthase genes CalS11-like and CalS12-like encode proteins that are essential for the formation of callose, a major component of pollen mother cell walls; these enzymes also function in callose formation during pathogen infection. This article describes the targeting of these callose synthase mRNAs by a small RNA derived from the virulence modulating region of two Potato spindle tuber viroid variants. More specifically, viroid infection of tomato plants resulted in the suppression of the target mRNAs up to 1.5-fold, depending on the viroid variant used and the gene targeted. The targeting of these mRNAs by RNA silencing was validated by artificial microRNA experiments in a transient expression system and by RNA ligase-mediated rapid amplification of cDNA ends. Viroid mutants incapable of targeting callose synthase mRNAs failed to induce typical infection phenotypes, whereas a chimeric viroid obtained by swapping the virulence modulating regions of a mild and a severe variant of Potato spindle tuber viroid greatly affected the accumulation of viroids and the severity of disease symptoms. These data provide evidence of the silencing of multiple genes by a single small RNA derived from a viroid. PMID:26290537

  7. Tocopherol deficiency reduces sucrose export from salt-stressed potato leaves independently of oxidative stress and symplastic obstruction by callose.

    PubMed

    Asensi-Fabado, María Amparo; Ammon, Alexandra; Sonnewald, Uwe; Munné-Bosch, Sergi; Voll, Lars M

    2015-02-01

    Tocopherol cyclase, encoded by the gene SUCROSE EXPORT DEFECTIVE1, catalyses the second step in the synthesis of the antioxidant tocopherol. Depletion of SXD1 activity in maize and potato leaves leads to tocopherol deficiency and a 'sugar export block' phenotype that comprises massive starch accumulation and obstruction of plasmodesmata in paraveinal tissue by callose. We grew two transgenic StSXD1:RNAi potato lines with severe tocopherol deficiency under moderate light conditions and subjected them to salt stress. After three weeks of salt exposure, we observed a strongly reduced sugar exudation rate and a lack of starch mobilization in leaves of salt-stressed transgenic plants, but not in wild-type plants. However, callose accumulation in the vasculature declined upon salt stress in all genotypes, indicating that callose plugging of plasmodesmata was not the sole cause of the sugar export block phenotype in tocopherol-deficient leaves. Based on comprehensive gene expression analyses, we propose that enhanced responsiveness of SnRK1 target genes in mesophyll cells and altered redox regulation of phloem loading by SUT1 contribute to the attenuation of sucrose export from salt-stressed SXD:RNAi source leaves. Furthermore, we could not find any indication that elevated oxidative stress may have served as a trigger for the salt-induced carbohydrate phenotype of SXD1:RNAi transgenic plants. In leaves of the SXD1:RNAi plants, sodium accumulation was diminished, while proline accumulation and pools of soluble antioxidants were increased. As supported by phytohormone contents, these differences seem to increase longevity and prevent senescence of SXD:RNAi leaves under salt stress.

  8. Periventricular nodular heterotopia, frontonasal encephalocele, corpus callosal dysgenesis and arachnoid cyst: A constellation of abnormalities in a child with epilepsy.

    PubMed

    Krishnan, Prasad; Chattopadhyay, Arijit; Saha, Manash

    2014-01-01

    A 7-year-old male child presented with poorly controlled generalized tonic-clonic seizures. On examination, he was mentally retarded, deaf and had a swelling at the root on the nose. Computed tomography scan done previously revealed a left temporal arachnoid cyst (AC) due to which he was referred for surgery. However, magnetic resonance imaging revealed a constellation of abnormalities - all of which could be responsible for his seizures. The combination of periventricular nodular heterotopias with encepaholcele is rarely described in the literature, and more infrequently so its combination with AC and callosal dysgenesis - the Chudley-Mccullough syndrome. We describe the case and review relevant literature on this subject.

  9. Secreted Fungal Effector Lipase Releases Free Fatty Acids to Inhibit Innate Immunity-Related Callose Formation during Wheat Head Infection[W][OPEN

    PubMed Central

    Blümke, Antje; Falter, Christian; Herrfurth, Cornelia; Sode, Björn; Bode, Rainer; Schäfer, Wilhelm; Feussner, Ivo; Voigt, Christian A.

    2014-01-01

    The deposition of the (1,3)-β-glucan cell wall polymer callose at sites of attempted penetration is a common plant defense response to intruding pathogens and part of the plant’s innate immunity. Infection of the Fusarium graminearum disruption mutant Δfgl1, which lacks the effector lipase FGL1, is restricted to inoculated wheat (Triticum aestivum) spikelets, whereas the wild-type strain colonized the whole wheat spike. Our studies here were aimed at analyzing the role of FGL1 in establishing full F. graminearum virulence. Confocal laser-scanning microscopy revealed that the Δfgl1 mutant strongly induced the deposition of spot-like callose patches in vascular bundles of directly inoculated spikelets, while these callose deposits were not observed in infections by the wild type. Elevated concentrations of the polyunsaturated free fatty acids (FFAs) linoleic and α-linolenic acid, which we detected in F. graminearum wild type-infected wheat spike tissue compared with Δfgl1-infected tissue, provided clear evidence for a suggested function of FGL1 in suppressing callose biosynthesis. These FFAs not only inhibited plant callose biosynthesis in vitro and in planta but also partially restored virulence to the Δfgl1 mutant when applied during infection of wheat spikelets. Additional FFA analysis confirmed that the purified effector lipase FGL1 was sufficient to release linoleic and α-linolenic acids from wheat spike tissue. We concluded that these two FFAs have a major function in the suppression of the innate immunity-related callose biosynthesis and, hence, the progress of F. graminearum wheat infection. PMID:24686113

  10. Activity-dependent serotonergic excitation of callosal projection neurons in the mouse prefrontal cortex

    PubMed Central

    Stephens, Emily K.; Avesar, Daniel; Gulledge, Allan T.

    2014-01-01

    Layer 5 pyramidal neurons (L5PNs) in the mouse prefrontal cortex respond to serotonin (5-HT) according to their long-distance axonal projections; 5-HT1A (1A) receptors mediate inhibitory responses in corticopontine (CPn) L5PNs, while 5-HT2A (2A) receptors can enhance action potential (AP) output in callosal/commissural (COM) L5PNs, either directly (in “COM-excited” neurons), or following brief 1A-mediated inhibition (in “COM-biphasic” neurons). Here we compare the impact of 5-HT on the excitability of CPn and COM L5PNs experiencing variable excitatory drive produced by current injection (DC current or simulated synaptic current) or with exogenous glutamate. 5-HT delivered at resting membrane potentials, or paired with subthreshold depolarizing input, hyperpolarized CPn and COM-biphasic L5PNs and failed to promote AP generation in COM-excited L5PNs. Conversely, when paired with suprathreshold excitatory drive generating multiple APs, 5-HT suppressed AP output in CPn L5PNs, enhanced AP generation in COM-excited L5PNs, and generated variable responses in COM-biphasic L5PNs. While COM-excited neurons failed to respond to 5-HT in the presence of a 2A receptor antagonist, 32% of CPn neurons exhibited 2A-dependent excitation following blockade of 1A receptors. The presence of pharmacologically revealed 2A receptors in CPn L5PNs was correlated with the duration of 1A-mediated inhibition, yet biphasic excitatory responses to 5-HT were never observed, even when 5-HT was paired with strong excitatory drive. Our results suggest that 2A receptors selectively amplify the output of COM L5PNs experiencing suprathreshold excitatory drive, while shaping the duration of 1A-mediated inhibition in a subset of CPn L5PNs. Activity-dependent serotonergic excitation of COM L5PNs, combined with 1A-mediated inhibition of CPn and COM-biphasic L5PNs, may facilitate executive function by focusing network activity within cortical circuits subserving the most appropriate behavioral output

  11. Auditory efferent activation in CBA mice exceeds that of C57s for varying levels of noise.

    PubMed

    Frisina, Robert D; Newman, S R; Zhu, Xiaoxia

    2007-01-01

    The medial olivocochlear efferent (MOC) system enhances signals in noise and helps mediate auditory attention. Contralateral suppression (CS) of distortion product otoacoustic emissions (DPOAEs) has revealed age-related MOC declines. Here, differences in CS as a function of contralateral noise intensity (43-67 dB sound pressure level) were measured; 2f1-f2 DPOAE grams were recorded for young adult CBA and C57 mice. In CBAs, CS was a monotonic function of contralateral noise level. The C57s showed normal hearing, measured with DPOAE amplitudes and auditory brainstem response thresholds, but showed little CS, suggesting a loss of efferent dynamics preceding any deficiencies of the afferent auditory system.

  12. Increased Efferent Cardiac Sympathetic Nerve Activity and Defective Intrinsic Heart Rate Regulation in Type 2 Diabetes.

    PubMed

    Thaung, H P Aye; Baldi, J Chris; Wang, Heng-Yu; Hughes, Gillian; Cook, Rosalind F; Bussey, Carol T; Sheard, Phil W; Bahn, Andrew; Jones, Peter P; Schwenke, Daryl O; Lamberts, Regis R

    2015-08-01

    Elevated sympathetic nerve activity (SNA) coupled with dysregulated β-adrenoceptor (β-AR) signaling is postulated as a major driving force for cardiac dysfunction in patients with type 2 diabetes; however, cardiac SNA has never been assessed directly in diabetes. Our aim was to measure the sympathetic input to and the β-AR responsiveness of the heart in the type 2 diabetic heart. In vivo recording of SNA of the left efferent cardiac sympathetic branch of the stellate ganglion in Zucker diabetic fatty rats revealed an elevated resting cardiac SNA and doubled firing rate compared with nondiabetic rats. Ex vivo, in isolated denervated hearts, the intrinsic heart rate was markedly reduced. Contractile and relaxation responses to β-AR stimulation with dobutamine were compromised in externally paced diabetic hearts, but not in diabetic hearts allowed to regulate their own heart rate. Protein levels of left ventricular β1-AR and Gs (guanine nucleotide binding protein stimulatory) were reduced, whereas left ventricular and right atrial β2-AR and Gi (guanine nucleotide binding protein inhibitory regulatory) levels were increased. The elevated resting cardiac SNA in type 2 diabetes, combined with the reduced cardiac β-AR responsiveness, suggests that the maintenance of normal cardiovascular function requires elevated cardiac sympathetic input to compensate for changes in the intrinsic properties of the diabetic heart.

  13. Retinal afferents and efferents of an infrared sensitive snake, Crotalus viridis

    SciTech Connect

    Schroeder, D.M.

    1981-01-01

    The retinal afferents and efferents were examined in Crotalus viridis. Retinofugal fibers were traced by injecting horseradish peroxidase (HRP) or tritiated leucine into the eye, or by removing the eye and staining degenerating axons with silver methods. Terminations were seen contralaterally in the suprachiasmatic nucleus, the dorsal and ventral lateral geniculate nuclei (extensive), the pretectal nuclei, including the nucleus posterodorsalis (a very heavy input), the nucleus lentiformis mesencephali, nucleus geniculatus pretectalis, and nucleus pretectalis, the superficial layers of the optic tectum, including the stratum zonale, the stratum opticum, the stratum griseum et fibrosum centrale and the upper portion of stratum griseum centrale, and the basal optic nucleus. Ipsilateral input reaches the intermediate portion of the dorsal lateral geniculate nucleus, a small portion of the pretectal nucleus and nucleus posterodorsalis, and the basal optic nucleus (very minimally). Retinopedal fibers were traced with the HRP method. The cell bodies lie in the ventral thalamus within the nucleus of the ventral supraoptic decussation. These neurons project primarily to the contralateral retina, but some more rostrally located neurons project to the ipsilateral retina.

  14. Mushroom body efferent neurons responsible for aversive olfactory memory retrieval in Drosophila.

    PubMed

    Séjourné, Julien; Plaçais, Pierre-Yves; Aso, Yoshinori; Siwanowicz, Igor; Trannoy, Séverine; Thoma, Vladimiros; Tedjakumala, Stevanus R; Rubin, Gerald M; Tchénio, Paul; Ito, Kei; Isabel, Guillaume; Tanimoto, Hiromu; Preat, Thomas

    2011-06-19

    Aversive olfactory memory is formed in the mushroom bodies in Drosophila melanogaster. Memory retrieval requires mushroom body output, but the manner in which a memory trace in the mushroom body drives conditioned avoidance of a learned odor remains unknown. To identify neurons that are involved in olfactory memory retrieval, we performed an anatomical and functional screen of defined sets of mushroom body output neurons. We found that MB-V2 neurons were essential for retrieval of both short- and long-lasting memory, but not for memory formation or memory consolidation. MB-V2 neurons are cholinergic efferent neurons that project from the mushroom body vertical lobes to the middle superiormedial protocerebrum and the lateral horn. Notably, the odor response of MB-V2 neurons was modified after conditioning. As the lateral horn has been implicated in innate responses to repellent odorants, we propose that MB-V2 neurons recruit the olfactory pathway involved in innate odor avoidance during memory retrieval.

  15. Stronger efferent suppression of cochlear neural potentials by contralateral acoustic stimulation in awake than in anesthetized chinchilla

    PubMed Central

    Aedo, Cristian; Tapia, Eduardo; Pavez, Elizabeth; Elgueda, Diego; Delano, Paul H.; Robles, Luis

    2015-01-01

    There are two types of sensory cells in the mammalian cochlea, inner hair cells, which make synaptic contact with auditory-nerve afferent fibers, and outer hair cells that are innervated by crossed and uncrossed medial olivocochlear (MOC) efferent fibers. Contralateral acoustic stimulation activates the uncrossed efferent MOC fibers reducing cochlear neural responses, thus modifying the input to the central auditory system. The chinchilla, among all studied mammals, displays the lowest percentage of uncrossed MOC fibers raising questions about the strength and frequency distribution of the contralateral-sound effect in this species. On the other hand, MOC effects on cochlear sensitivity have been mainly studied in anesthetized animals and since the MOC-neuron activity depends on the level of anesthesia, it is important to assess the influence of anesthesia in the strength of efferent effects. Seven adult chinchillas (Chinchilla laniger) were chronically implanted with round-window electrodes in both cochleae. We compared the effect of contralateral sound in awake and anesthetized condition. Compound action potentials (CAP) and cochlear microphonics (CM) were measured in the ipsilateral cochlea in response to tones in absence and presence of contralateral sound. Control measurements performed after middle-ear muscles section in one animal discarded any possible middle-ear reflex activation. Contralateral sound produced CAP amplitude reductions in all chinchillas, with suppression effects greater by about 1–3 dB in awake than in anesthetized animals. In contrast, CM amplitude increases of up to 1.9 dB were found in only three awake chinchillas. In both conditions the strongest efferent effects were produced by contralateral tones at frequencies equal or close to those of ipsilateral tones. Contralateral CAP suppressions for 1–6 kHz ipsilateral tones corresponded to a span of uncrossed MOC fiber innervation reaching at least the central third of the chinchilla

  16. Stronger efferent suppression of cochlear neural potentials by contralateral acoustic stimulation in awake than in anesthetized chinchilla.

    PubMed

    Aedo, Cristian; Tapia, Eduardo; Pavez, Elizabeth; Elgueda, Diego; Delano, Paul H; Robles, Luis

    2015-01-01

    There are two types of sensory cells in the mammalian cochlea, inner hair cells, which make synaptic contact with auditory-nerve afferent fibers, and outer hair cells that are innervated by crossed and uncrossed medial olivocochlear (MOC) efferent fibers. Contralateral acoustic stimulation activates the uncrossed efferent MOC fibers reducing cochlear neural responses, thus modifying the input to the central auditory system. The chinchilla, among all studied mammals, displays the lowest percentage of uncrossed MOC fibers raising questions about the strength and frequency distribution of the contralateral-sound effect in this species. On the other hand, MOC effects on cochlear sensitivity have been mainly studied in anesthetized animals and since the MOC-neuron activity depends on the level of anesthesia, it is important to assess the influence of anesthesia in the strength of efferent effects. Seven adult chinchillas (Chinchilla laniger) were chronically implanted with round-window electrodes in both cochleae. We compared the effect of contralateral sound in awake and anesthetized condition. Compound action potentials (CAP) and cochlear microphonics (CM) were measured in the ipsilateral cochlea in response to tones in absence and presence of contralateral sound. Control measurements performed after middle-ear muscles section in one animal discarded any possible middle-ear reflex activation. Contralateral sound produced CAP amplitude reductions in all chinchillas, with suppression effects greater by about 1-3 dB in awake than in anesthetized animals. In contrast, CM amplitude increases of up to 1.9 dB were found in only three awake chinchillas. In both conditions the strongest efferent effects were produced by contralateral tones at frequencies equal or close to those of ipsilateral tones. Contralateral CAP suppressions for 1-6 kHz ipsilateral tones corresponded to a span of uncrossed MOC fiber innervation reaching at least the central third of the chinchilla cochlea.

  17. Reconstruction of atonic bladder innervation after spinal cord injury: A bladder reflex arc with afferent and efferent pathways.

    PubMed

    He, Jun; Li, Guitao; Luo, Dixin; Sun, Hongtao; Qi, Yong; Li, Yiyi; Jin, Xunjie

    2015-11-01

    Background Establishing bladder reflex arcs only with the efferent pathway to induce micturition after spinal cord injury (SCI) has been successful. However, the absence of sensory function and micturition desires can lead to serious complications. Objectives To reconstruct a bladder reflex arc with both afferent and efferent pathways to achieve atonic bladder innervation after SCI. Methods A reflex arc was established by microanastomosis of the S2 dorsal root to the peripheral process of the L5 dorsal ganglion and the L5 ventral root to the S2 ventral root. The functions of the reflex arc were evaluated using electrophysiology, wheat germ agglutinin-horseradish peroxidase (WGA-HRP) tracing, and calcitonin gene-related peptide (CGRP) immunocytochemistry analysis. Hind-paw motion was evaluated by CatWalk gait. Results Compound action potentials and compound muscle action potentials were recorded at the right L5 dorsal root following electrical stimulation of right S2 dorsal root. Similar to the control side, these were not significantly different before or after the spinal cord destruction between L6 and S4. WGA-HRP tracing and CGRP immunocytochemistry showed that construction of the afferent and efferent pathways of the bladder reflex arc encouraged axonal regeneration of motor and sensory nerves, which then made contact with the anterior and posterior horns of the spinal cord, ultimately reestablishing axoplasmic transportation. Gait analysis showed that at 3 months following the operation, only the regularity index was significantly different as compared with 1 day before the operation, other parameters showing no difference. Conclusion Bladder reflex arc with the afferent and efferent pathways reconstructs the micturition function without great influence on the motion of leg.

  18. Stronger efferent suppression of cochlear neural potentials by contralateral acoustic stimulation in awake than in anesthetized chinchilla.

    PubMed

    Aedo, Cristian; Tapia, Eduardo; Pavez, Elizabeth; Elgueda, Diego; Delano, Paul H; Robles, Luis

    2015-01-01

    There are two types of sensory cells in the mammalian cochlea, inner hair cells, which make synaptic contact with auditory-nerve afferent fibers, and outer hair cells that are innervated by crossed and uncrossed medial olivocochlear (MOC) efferent fibers. Contralateral acoustic stimulation activates the uncrossed efferent MOC fibers reducing cochlear neural responses, thus modifying the input to the central auditory system. The chinchilla, among all studied mammals, displays the lowest percentage of uncrossed MOC fibers raising questions about the strength and frequency distribution of the contralateral-sound effect in this species. On the other hand, MOC effects on cochlear sensitivity have been mainly studied in anesthetized animals and since the MOC-neuron activity depends on the level of anesthesia, it is important to assess the influence of anesthesia in the strength of efferent effects. Seven adult chinchillas (Chinchilla laniger) were chronically implanted with round-window electrodes in both cochleae. We compared the effect of contralateral sound in awake and anesthetized condition. Compound action potentials (CAP) and cochlear microphonics (CM) were measured in the ipsilateral cochlea in response to tones in absence and presence of contralateral sound. Control measurements performed after middle-ear muscles section in one animal discarded any possible middle-ear reflex activation. Contralateral sound produced CAP amplitude reductions in all chinchillas, with suppression effects greater by about 1-3 dB in awake than in anesthetized animals. In contrast, CM amplitude increases of up to 1.9 dB were found in only three awake chinchillas. In both conditions the strongest efferent effects were produced by contralateral tones at frequencies equal or close to those of ipsilateral tones. Contralateral CAP suppressions for 1-6 kHz ipsilateral tones corresponded to a span of uncrossed MOC fiber innervation reaching at least the central third of the chinchilla cochlea

  19. Cell wall maturation of Arabidopsis trichomes is dependent on exocyst subunit EXO70H4 and involves callose deposition.

    PubMed

    Kulich, Ivan; Vojtíková, Zdeňka; Glanc, Matouš; Ortmannová, Jitka; Rasmann, Sergio; Žárský, Viktor

    2015-05-01

    Arabidopsis (Arabidopsis thaliana) leaf trichomes are single-cell structures with a well-studied development, but little is understood about their function. Developmental studies focused mainly on the early shaping stages, and little attention has been paid to the maturation stage. We focused on the EXO70H4 exocyst subunit, one of the most up-regulated genes in the mature trichome. We uncovered EXO70H4-dependent development of the secondary cell wall layer, highly autofluorescent and callose rich, deposited only in the upper part of the trichome. The boundary is formed between the apical and the basal parts of mature trichome by a callose ring that is also deposited in an EXO70H4-dependent manner. We call this structure the Ortmannian ring (OR). Both the secondary cell wall layer and the OR are absent in the exo70H4 mutants. Ecophysiological aspects of the trichome cell wall thickening include interference with antiherbivore defense and heavy metal accumulation. Ultraviolet B light induces EXO70H4 transcription in a CONSTITUTIVE PHOTOMORPHOGENIC1-dependent way, resulting in stimulation of trichome cell wall thickening and the OR biogenesis. EXO70H4-dependent trichome cell wall hardening is a unique phenomenon, which may be conserved among a variety of the land plants. Our analyses support a concept that Arabidopsis trichome is an excellent model to study molecular mechanisms of secondary cell wall deposition. PMID:25767057

  20. Chemical Topography of Efferent Projections from the Median Preoptic Nucleus to Pontine Monoaminergic Cell Groups in the Rat

    NASA Technical Reports Server (NTRS)

    Zardetto-Smith, Andrea M.; Johnson, Alan Kim

    1995-01-01

    This study examined efferent output from the median preoptic nucleus (MnPO) to pontine noradrenergic and serotonergic cell groups using an anterograde tracing technique (Phaseolus vulgaris leucoagglutinin, PHA-L) combined with glucose oxidase immunocytochemistry to scrotonin (5-HT) or to dopamine-(beta)-hydroxylase (DBH). Injections of PHA-L into the ventral MNPO resulted in moderate axonal labeling within the region of the B7 and B8 serotonergic groups in the dorsal raphe. PHA-L labeled fibers and punctate processes were observed in close apposition to many of the 5-HT immunoreactive neurons in these regions, In contrast, sparse terminal labeling was found within the B5 group in the raphe pontis nucleus, and only trace fiber labeling observed in the B3 and B6 groups. Efferents from the MNPO also provided moderate innervation to the A6 and A7 noradrenergic groups. PHA-L labeled punctate processes were found most frequently in close apposition to DBH-immunorcactive neurons at mid- to caudal levels of the locus coeruleus. Some labeled axons were also present within the A7 and A5 groups. Additionally, a close apposition between labeled MNPO efferents and 5-HT fibers within the lateral parabrachial nucleus was observed, The results indicate the MNPO provides a topographic innerva- tion of monoaminergic groups in the upper brainstem.

  1. Chemical Topography of Efferent Projections from the Median Preoptic Nucleus to Pontine Monoaminergic Cell Groups in the Rat

    NASA Technical Reports Server (NTRS)

    Zardetto-Smith, Andrea M.; Johnson, Alan Kim

    1995-01-01

    This study examined efferent output from the median preoptic nucleus (MNPO) to pontine noradrenergic and serotonergic cell groups using an anterograde tracing technique (Phaseolus vulgaris leucoagglutinin, PHA-L) combined with glucose oxidase immunocytochemistry to serotonin (5-HT) or to dopamine-beta-hydroxylase (DBH). Injections of PHA-L into the ventral MNPO resulted in moderate axonal labeling within the region of the B7 and B8 serotonergic groups in the dorsal raphe. PHA-L labeled fibers and punctate processes were observed in close apposition to many of the 5-HT immunoreactive neurons in these regions. In contrast, sparse terminal labeling was found within the B5 group in the raphe pontis nucleus, and only trace fiber labeling observed in the B3 and B6 groups. Efferents from the MNPO also provided moderate innervation to the A6 and A7 noradrenergic groups. PHA-L labeled punctate processes were found most frequently in close apposition to DBH-immunoreactive neurons at mid- to caudal levels of the locus coeruleus. Some labeled axons were also present within the A7 and A5 groups. Additionally, a close apposition between labeled MNPO efferents and 5-HT fibers within the lateral parabrachial nucleus was observed. The results indicate the MNPO provides a topographic innervation of monoaminergic groups in the upper brainstem.

  2. Preservation of Acute pain and Efferent Functions Following Intrathecal Resiniferatoxin-Induced Analgesia in rats

    PubMed Central

    Bishnoi, Mahendra; Bosgraaf, Christine A.; Premkumar, Louis S.

    2013-01-01

    Resiniferatoxin (RTX) is a potent agonist of TRPV1, which possesses unique properties that can be utilized to treat certain modalities of pain. In the present study, systemic intraperitoneal (i.p.) administration of RTX resulted in a significant decrease in acute thermal pain sensitivity, whereas localized intrathecal (i.t.) administration had no effect on acute thermal pain sensitivity. Both i.p. and i.t. administration of RTX prevented TRPV1-induced nocifensive behavior and inflammatory thermal hypersensitivity. There were no alterations in mechanical sensitivity either by i.p. of i.t. administration of RTX. In spinal dorsal horn (L4-L6), TRPV1 and substance P immunoreactivity were abolished following i.p. and i.t. administration of RTX. In dorsal root ganglia (DRG), TRPV1 immunoreactivity was diminished following i.p. administration, but was unaffected following i.t. administration of RTX. Following i.p. administration, basal and evoked CGRP release was reduced both in the spinal cord and peripheral tissues. However, following i.t. administration, basal and evoked CGRP release was reduced in spinal cord (L4-L6), but was unaffected in peripheral tissues. Both i.p. and i.t. RTX administration lowered the body temperature acutely, but this effect reversed with time. Targeting TRPV1 expressing nerve terminals at the spinal cord can selectively abolish inflammatory thermal hypersensitivity without affecting acute thermal sensitivity and can preserve the efferent functions of DRG neurons at the peripheral nerve terminals. I.t. administration of RTX can be considered as a strategy for treating certain chronic and debilitating pain conditions. PMID:21680254

  3. Coronary responses to cold air inhalation following afferent and efferent blockade

    PubMed Central

    Gao, Zhaohui; McQuillan, Patrick M.; Leuenberger, Urs A.; Sinoway, Lawrence I.

    2014-01-01

    Cardiac ischemia and angina pectoris are commonly experienced during exertion in a cold environment. In the current study we tested the hypotheses that oropharyngeal afferent blockade (i.e., local anesthesia of the upper airway with lidocaine) as well as systemic β-adrenergic receptor blockade (i.e., intravenous propranolol) would improve the balance between myocardial oxygen supply and demand in response to the combined stimulus of cold air inhalation (−15 to −30°C) and isometric handgrip exercise (Cold + Grip). Young healthy subjects underwent Cold + Grip following lidocaine, propranolol, and control (no drug). Heart rate, blood pressure, and coronary blood flow velocity (CBV, from Doppler echocardiography) were continuously measured. Rate-pressure product (RPP) was calculated, and changes from baseline were compared between treatments. The change in RPP at the end of Cold + Grip was not different between lidocaine (2,441 ± 376) and control conditions (3,159 ± 626); CBV responses were also not different between treatments. With propranolol, heart rate (8 ± 1 vs. 14 ± 3 beats/min) and RPP responses to Cold + Grip were significantly attenuated. However, at peak exercise propranolol also resulted in a smaller ΔCBV (1.4 ± 0.8 vs. 5.3 ± 1.4 cm/s, P = 0.035), such that the relationship between coronary flow and cardiac metabolism was impaired under propranolol (0.43 ± 0.37 vs. 2.1 ± 0.63 arbitrary units). These data suggest that cold air breathing and isometric exercise significantly influence efferent control of coronary blood flow. Additionally, β-adrenergic vasodilation may play a significant role in coronary regulation during exercise. PMID:24816257

  4. Monocular distance estimation with optical flow maneuvers and efference copies: a stability-based strategy.

    PubMed

    de Croon, Guido C H E

    2016-02-01

    The visual cue of optical flow plays an important role in the navigation of flying insects, and is increasingly studied for use by small flying robots as well. A major problem is that successful optical flow control seems to require distance estimates, while optical flow is known to provide only the ratio of velocity to distance. In this article, a novel, stability-based strategy is proposed for monocular distance estimation, relying on optical flow maneuvers and knowledge of the control inputs (efference copies). It is shown analytically that given a fixed control gain, the stability of a constant divergence control loop only depends on the distance to the approached surface. At close distances, the control loop starts to exhibit self-induced oscillations. The robot can detect these oscillations and hence be aware of the distance to the surface. The proposed stability-based strategy for estimating distances has two main attractive characteristics. First, self-induced oscillations can be detected robustly by the robot and are hardly influenced by wind. Second, the distance can be estimated during a zero divergence maneuver, i.e., around hover. The stability-based strategy is implemented and tested both in simulation and on board a Parrot AR drone 2.0. It is shown that the strategy can be used to: (1) trigger a final approach response during a constant divergence landing with fixed gain, (2) estimate the distance in hover, and (3) estimate distances during an entire landing if the robot uses adaptive gain control to continuously stay on the 'edge of oscillation.' PMID:26740501

  5. Monocular distance estimation with optical flow maneuvers and efference copies: a stability-based strategy.

    PubMed

    de Croon, Guido C H E

    2016-01-07

    The visual cue of optical flow plays an important role in the navigation of flying insects, and is increasingly studied for use by small flying robots as well. A major problem is that successful optical flow control seems to require distance estimates, while optical flow is known to provide only the ratio of velocity to distance. In this article, a novel, stability-based strategy is proposed for monocular distance estimation, relying on optical flow maneuvers and knowledge of the control inputs (efference copies). It is shown analytically that given a fixed control gain, the stability of a constant divergence control loop only depends on the distance to the approached surface. At close distances, the control loop starts to exhibit self-induced oscillations. The robot can detect these oscillations and hence be aware of the distance to the surface. The proposed stability-based strategy for estimating distances has two main attractive characteristics. First, self-induced oscillations can be detected robustly by the robot and are hardly influenced by wind. Second, the distance can be estimated during a zero divergence maneuver, i.e., around hover. The stability-based strategy is implemented and tested both in simulation and on board a Parrot AR drone 2.0. It is shown that the strategy can be used to: (1) trigger a final approach response during a constant divergence landing with fixed gain, (2) estimate the distance in hover, and (3) estimate distances during an entire landing if the robot uses adaptive gain control to continuously stay on the 'edge of oscillation.'

  6. The efference cascade, consciousness, and its self: naturalizing the first person pivot of action control

    PubMed Central

    Merker, Bjorn

    2013-01-01

    The 20 billion neurons of the neocortex have a mere hundred thousand motor neurons by which to express cortical contents in overt behavior. Implemented through a staggered cortical “efference cascade” originating in the descending axons of layer five pyramidal cells throughout the neocortical expanse, this steep convergence accomplishes final integration for action of cortical information through a system of interconnected subcortical way stations. Coherent and effective action control requires the inclusion of a continually updated joint “global best estimate” of current sensory, motivational, and motor circumstances in this process. I have previously proposed that this running best estimate is extracted from cortical probabilistic preliminaries by a subcortical neural “reality model” implementing our conscious sensory phenomenology. As such it must exhibit first person perspectival organization, suggested to derive from formating requirements of the brain's subsystem for gaze control, with the superior colliculus at its base. Gaze movements provide the leading edge of behavior by capturing targets of engagement prior to contact. The rotation-based geometry of directional gaze movements places their implicit origin inside the head, a location recoverable by cortical probabilistic source reconstruction from the rampant primary sensory variance generated by the incessant play of collicularly triggered gaze movements. At the interface between cortex and colliculus lies the dorsal pulvinar. Its unique long-range inhibitory circuitry may precipitate the brain's global best estimate of its momentary circumstances through multiple constraint satisfaction across its afferents from numerous cortical areas and colliculus. As phenomenal content of our sensory awareness, such a global best estimate would exhibit perspectival organization centered on a purely implicit first person origin, inherently incapable of appearing as a phenomenal content of the sensory

  7. Uridine Diphosphate Glucose Metabolism and Callose Synthesis in Cultured Pollen Tubes of Nicotiana alata Link et Otto.

    PubMed Central

    Schlupmann, H.; Bacic, A.; Read, S. M.

    1994-01-01

    Membrane preparations from cultured pollen tubes of Nicotiana alata Link et Otto contain a Ca2+ -independent (1-3)-[beta]-D-glucan (callose) synthase activity that has a low affinity for UDP-glucose, even when activated by treatment with trypsin (H. Schlupmann, A. Basic, S.M. Read [1993] Planta 191: 470-481). Therefore, we investigated whether UDP-glucose was a likely substrate for callose synthesis in actively growing pollen tubes. Deposition of (1-3)-[beta]-glucan occurred at a constant rate, 1.4 to 1.7 nmol glucose min-1, in tubes from 1 mg of pollen from 3 h after germination; however, the rate of incorporation of radioactivity from exogenous [14C]-sucrose into wall polymers was not constant, but increased until at least 8 h after germination, probably due to decreasing use of internal reserves. UDP-glucose was a prominent ultraviolet-absorbing metabolite in pollen-tube extracts, with 1.6 nmol present in tubes from 1 mg of pollen, giving a calculated cytoplasmic concentration of approximately 3.5 mM. Radioactivity from [14C]-sucrose was rapidly incorporated into sugar monophosphates and UDP-glucose by the growing tubes, consistent with a turnover time for UDP-glucose of less than 1 min; the specific radioactivity of extracted UDP-[14C]glucose was equal to that calculated from the rate of incorporation of [14C]sucrose into wall glucans. Large amounts of less metabolically active neutral sugars were also present. The rate of synthesis of (1-3)-[beta]-glucan by nontrypsin-treated pollen-tube membrane preparations incubated with 3.5 mM UDP-glucose and a [beta]-glucoside activator was slightly greater than the rate of deposition of (1-3)-[beta]-glucan by intact pollen tubes. These data are used to assess the physiological significance of proteolytic activation of pollen-tube callose synthase. PMID:12232233

  8. Periventricular nodular heterotopia, frontonasal encephalocele, corpus callosal dysgenesis and arachnoid cyst: A constellation of abnormalities in a child with epilepsy

    PubMed Central

    Krishnan, Prasad; Chattopadhyay, Arijit; Saha, Manash

    2014-01-01

    A 7-year-old male child presented with poorly controlled generalized tonic-clonic seizures. On examination, he was mentally retarded, deaf and had a swelling at the root on the nose. Computed tomography scan done previously revealed a left temporal arachnoid cyst (AC) due to which he was referred for surgery. However, magnetic resonance imaging revealed a constellation of abnormalities – all of which could be responsible for his seizures. The combination of periventricular nodular heterotopias with encepaholcele is rarely described in the literature, and more infrequently so its combination with AC and callosal dysgenesis – the Chudley-Mccullough syndrome. We describe the case and review relevant literature on this subject. PMID:25624936

  9. Progressive Wallerian Degeneration of the Corpus Callosal Splenium in a Patient with Alexia Without Agraphia: Advanced MR Findings.

    PubMed

    Gandhi, Kriti; Gillihan, Laura; Wozniak, Marcella A; Zhuo, Jiachen; Raghavan, Prashant

    2014-12-01

    The corpus callosal splenium is an uncommon location for Wallerian degeneration (WD), which may be mistaken for new pathology on magnetic resonance imaging (MRI). We describe the case of a 69-year-old woman with a left posterior cerebral artery infarct in whom progressive WD of the splenium of the corpus callosum seen on MRI was misinterpreted as new infarction or neoplasm. We address how magnetic resonance spectroscopy, perfusion MRI, diffusion tensor MRI, and serial imaging were utilized in establishing the correct diagnosis. Interestingly, the patient also presented with alexia without agraphia, which has never been reported in association with splenial WD. It is conceivable that WD affected critical splenial association fibers resulting in this uncommon dissociation syndrome. PMID:25489886

  10. Deterioration of the Medial Olivocochlear Efferent System Accelerates Age-Related Hearing Loss in Pax2-Isl1 Transgenic Mice.

    PubMed

    Chumak, Tetyana; Bohuslavova, Romana; Macova, Iva; Dodd, Nicole; Buckiova, Daniela; Fritzsch, Bernd; Syka, Josef; Pavlinkova, Gabriela

    2016-05-01

    The development, maturation, and maintenance of the inner ear are governed by temporal and spatial expression cascades of transcription factors that form a gene regulatory network. ISLET1 (ISL1) may be one of the major players in this cascade, and in order to study its role in the regulation of inner ear development, we produced a transgenic mouse overexpressing Isl1 under the Pax2 promoter. Pax2-regulated ISL1 overexpression increases the embryonic ISL1(+) domain and induces accelerated nerve fiber extension and branching in E12.5 embryos. Despite these gains in early development, the overexpression of ISL1 impairs the maintenance and function of hair cells of the organ of Corti. Mutant mice exhibit hyperactivity, circling behavior, and progressive age-related decline in hearing functions, which is reflected in reduced otoacoustic emissions (DPOAEs) followed by elevated hearing thresholds. The reduction of the amplitude of DPOAEs in transgenic mice was first detected at 1 month of age. By 6-9 months of age, DPOAEs completely disappeared, suggesting a functional inefficiency of outer hair cells (OHCs). The timing of DPOAE reduction coincides with the onset of the deterioration of cochlear efferent terminals. In contrast to these effects on efferents, we only found a moderate loss of OHCs and spiral ganglion neurons. For the first time, our results show that the genetic alteration of the medial olivocochlear (MOC) efferent system induces an early onset of age-related hearing loss. Thus, the neurodegeneration of the MOC system could be a contributing factor to the pathology of age-related hearing loss.

  11. Auditory efferent feedback system deficits precede age-related hearing loss: contralateral suppression of otoacoustic emissions in mice.

    PubMed

    Zhu, Xiaoxia; Vasilyeva, Olga N; Kim, Sunghee; Jacobson, Michael; Romney, Joshua; Waterman, Marjorie S; Tuttle, David; Frisina, Robert D

    2007-08-10

    The C57BL/6J mouse has been a useful model of presbycusis, as it displays an accelerated age-related peripheral hearing loss. The medial olivocochlear efferent feedback (MOC) system plays a role in suppressing cochlear outer hair cell (OHC) responses, particularly for background noise. Neurons of the MOC system are located in the superior olivary complex, particularly in the dorsomedial periolivary nucleus (DMPO) and in the ventral nucleus of the trapezoid body (VNTB). We previously discovered that the function of the MOC system declines with age prior to OHC degeneration, as measured by contralateral suppression (CS) of distortion product otoacoustic emissions (DPOAEs) in humans and CBA mice. The present study aimed to determine the time course of age changes in MOC function in C57s. DPOAE amplitudes and CS of DPOAEs were collected for C57s from 6 to 40 weeks of age. MOC responses were observed at 6 weeks but were gone at middle (15-30 kHz) and high (30-45 kHz) frequencies by 8 weeks. Quantitative stereological analyses of Nissl sections revealed smaller neurons in the DMPO and VNTB of young adult C57s compared with CBAs. These findings suggest that reduced neuron size may underlie part of the noteworthy rapid decline of the C57 efferent system. In conclusion, the C57 mouse has MOC function at 6 weeks, but it declines quickly, preceding the progression of peripheral age-related sensitivity deficits and hearing loss in this mouse strain.

  12. Chronic stress alters the dendritic morphology of callosal neurons and the acute glutamate stress response in the rat medial prefrontal cortex.

    PubMed

    Luczynski, Pauline; Moquin, Luc; Gratton, Alain

    2015-01-01

    We have previously reported that interhemispheric regulation of medial prefrontal cortex (PFC)-mediated stress responses is subserved by glutamate (GLU)- containing callosal neurons. Evidence of chronic stress-induced dendritic and spine atrophy among PFC pyramidal neurons led us to examine how chronic restraint stress (CRS) might alter the apical dendritic morphology of callosal neurons and the acute GLU stress responses in the left versus right PFC. Morphometric analyses of retrogradely labeled, dye-filled PFC callosal neurons revealed hemisphere-specific CRS-induced dendritic retraction; whereas significant dendritic atrophy occurred primarily within the distal arbor of left PFC neurons, it was observed within both the proximal and distal arbor of right PFC neurons. Overall, CRS also significantly reduced spine densities in both hemispheres with the greatest loss occurring among left PFC neurons, mostly at the distal extent of the arbor. While much of the overall decrease in dendritic spine density was accounted by the loss of thin spines, the density of mushroom-shaped spines, despite being fewer in number, was halved. Using microdialysis we found that, compared to controls, basal PFC GLU levels were significantly reduced in both hemispheres of CRS animals and that their GLU response to 30 min of tail-pinch stress was significantly prolonged in the left, but not the right PFC. Together, these findings show that a history of chronic stress alters the dendritic morphology and spine density of PFC callosal neurons and suggest a mechanism by which this might disrupt the interhemispheric regulation of PFC-mediated responses to subsequent stressors.

  13. Relationship between male sterility and β-1,3-glucanase activity and callose deposition-related gene expression in wheat (Triticum aestivum L.).

    PubMed

    Liu, H Z; Zhang, G S; Zhu, W W; Ba, Q S; Niu, N; Wang, J W; Ma, S C; Wang, J S

    2015-01-26

    In previous studies, we first isolated one different protein β-1,3-glucanase using two-dimensional electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry from normal wheat (Triticum aestivum L.) and chemical hybridization agent-induced male sterility (CIMS) wheat. In this experiment, β-1,3-glucanase activity and the expression of a callose deposition-related gene, UDP-glucose phosphorylase (UGPase), were determinate in normal, CIMS, and genetic male sterility (GS) wheat. β-1,3-glucanase activity was significantly different between the fertile and sterile lines during callose synthesis and degradation, but there was no difference between CIMS and GS wheat. The UGPase gene of callose deposition was highly expressed in the meiophase and sharply decreased in the tetrad stage. However, the expression of the UGPase gene was significantly different between the fertile and sterile lines. These data indicated that β-1,3-glucanase activity and the expression of the UGPase gene play important roles in the male sterility of wheat. Consequently, pollen mother cells (PMCs) might degenerate at the early meiosis stage, and differences in UGPase gene expression and β-1,3-glucanase activity might eventually result in complete pollen collapse. In addition, the critical period of anther abortion might be the meiosis stage to the tetrad stage rather than what we previously thought, the mononuclear period.

  14. Subset of early radial glial progenitors that contribute to the development of callosal neurons is absent from avian brain.

    PubMed

    García-Moreno, Fernando; Molnár, Zoltán

    2015-09-01

    The classical view of mammalian cortical development suggests that pyramidal neurons are generated in a temporal sequence, with all radial glial cells (RGCs) contributing to both lower and upper neocortical layers. A recent opposing proposal suggests there is a subgroup of fate-restricted RGCs in the early neocortex, which generates only upper-layer neurons. Little is known about the existence of fate restriction of homologous progenitors in other vertebrate species. We investigated the lineage of selected Emx2+ [vertebrate homeobox gene related to Drosophila empty spiracles (ems)] RGCs in mouse neocortex and chick forebrain and found evidence for both sequential and fate-restricted programs only in mouse, indicating that these complementary populations coexist in the developing mammalian but not avian brain. Among a large population of sequentially programmed RGCs in the mouse brain, a subset of self-renewing progenitors lack neurogenic potential during the earliest phase of corticogenesis. After a considerable delay, these progenitors generate callosal upper-layer neurons and glia. On the other hand, we found no homologous delayed population in any sectors of the chick forebrain. This finding suggests that neurogenic delay of selected RGCs may be unique to mammals and possibly associated with the evolution of the corpus callosum. PMID:26305942

  15. Subset of early radial glial progenitors that contribute to the development of callosal neurons is absent from avian brain

    PubMed Central

    García-Moreno, Fernando; Molnár, Zoltán

    2015-01-01

    The classical view of mammalian cortical development suggests that pyramidal neurons are generated in a temporal sequence, with all radial glial cells (RGCs) contributing to both lower and upper neocortical layers. A recent opposing proposal suggests there is a subgroup of fate-restricted RGCs in the early neocortex, which generates only upper-layer neurons. Little is known about the existence of fate restriction of homologous progenitors in other vertebrate species. We investigated the lineage of selected Emx2+ [vertebrate homeobox gene related to Drosophila empty spiracles (ems)] RGCs in mouse neocortex and chick forebrain and found evidence for both sequential and fate-restricted programs only in mouse, indicating that these complementary populations coexist in the developing mammalian but not avian brain. Among a large population of sequentially programmed RGCs in the mouse brain, a subset of self-renewing progenitors lack neurogenic potential during the earliest phase of corticogenesis. After a considerable delay, these progenitors generate callosal upper-layer neurons and glia. On the other hand, we found no homologous delayed population in any sectors of the chick forebrain. This finding suggests that neurogenic delay of selected RGCs may be unique to mammals and possibly associated with the evolution of the corpus callosum. PMID:26305942

  16. Delineation of a deletion region critical for corpus callosal abnormalities in chromosome 1q43–q44

    PubMed Central

    Nagamani, Sandesh C Sreenath; Erez, Ayelet; Bay, Carolyn; Pettigrew, Anjana; Lalani, Seema R; Herman, Kristin; Graham, Brett H; Nowaczyk, Malgorzata JM; Proud, Monica; Craigen, William J; Hopkins, Bobbi; Kozel, Beth; Plunkett, Katie; Hixson, Patricia; Stankiewicz, Pawel; Patel, Ankita; Cheung, Sau Wai

    2012-01-01

    Submicroscopic deletions involving chromosome 1q43–q44 result in cognitive impairment, microcephaly, growth restriction, dysmorphic features, and variable involvement of other organ systems. A consistently observed feature in patients with this deletion are the corpus callosal abnormalities (CCAs), ranging from thinning and hypoplasia to complete agenesis. Previous studies attempting to delineate the critical region for CCAs have yielded inconsistent results. We conducted a detailed clinical and molecular characterization of seven patients with deletions of chromosome 1q43–q44. Using array comparative genomic hybridization, we mapped the size, extent, and genomic content of these deletions. Four patients had CCAs, and shared the smallest region of overlap that contains only three protein coding genes, CEP170, SDCCAG8, and ZNF238. One patient with a small deletion involving SDCCAG8 and AKT3, and another patient with an intragenic deletion of AKT3 did not have any CCA, implying that the loss of these two genes is unlikely to be the cause of CCA. CEP170 is expressed extensively in the brain, and encodes for a protein that is a component of the centrosomal complex. ZNF238 is involved in control of neuronal progenitor cells and survival of cortical neurons. Our results rule out the involvement of AKT3, and implicate CEP170 and/or ZNF238 as novel genes causative for CCA in patients with a terminal 1q deletion. PMID:21934713

  17. Effects of hexavalent chromium on microtubule organization, ER distribution and callose deposition in root tip cells of Allium cepa L.

    PubMed

    Eleftheriou, Eleftherios P; Adamakis, Ioannis-Dimosthenis S; Melissa, Pelagia

    2012-04-01

    The subcellular targets of hexavalent chromium [Cr(VI)] were examined in Allium cepa root tips with confocal laser scanning microscopy. Cr(VI) exerted dose- and time-dependent negative effects on root growth rate, the mitotic index and microtubule (MT) organization during cell division cycle. Interphase MTs were more resistant than the mitotic ones, but when affected they were shorter, sparse and disoriented. The preprophase band of MTs became poorly organized, branched or with fragmented MTs, whilst neither a perinuclear array nor a prophase spindle was formed. Metaphase spindles converged to eccentric mini poles or consisted of dissimilar halves and were unable to correctly orient the chromosomes. Anaphase spindles were less disturbed, but chromatids failed to separate; neither did they move to the poles. At telophase, projecting, lagging or bridging chromosomes and micronuclei also occurred. Phragmoplasts were unilaterally developed, split, located at unexpected sites and frequently dissociated from the branched and misaligned cell plates. Chromosomal aberrations were directly correlated with MT disturbance. The morphology and distribution of endoplasmic reticulum was severely perturbed and presumably contributed to MT disassembly. Heavy callose apposition was also induced by Cr(VI), maybe in the context of a cellular defence reaction. Results indicate that MTs are one of the main subcellular targets of Cr(VI), MT impairment underlies chromosomal and mitotic aberrations, and MTs may constitute a reliable biomonitoring system for Cr(VI) toxicity in plants. PMID:21633932

  18. Adenomatous Polyposis Coli Protein Deletion in Efferent Olivocochlear Neurons Perturbs Afferent Synaptic Maturation and Reduces the Dynamic Range of Hearing

    PubMed Central

    Hickman, Tyler T.; Liberman, M. Charles

    2015-01-01

    Normal hearing requires proper differentiation of afferent ribbon synapses between inner hair cells (IHCs) and spiral ganglion neurons (SGNs) that carry acoustic information to the brain. Within individual IHCs, presynaptic ribbons show a size gradient with larger ribbons on the modiolar face and smaller ribbons on the pillar face. This structural gradient is associated with a gradient of spontaneous rates and threshold sensitivity, which is essential for a wide dynamic range of hearing. Despite their importance for hearing, mechanisms that direct ribbon differentiation are poorly defined. We recently identified adenomatous polyposis coli protein (APC) as a key regulator of interneuronal synapse maturation. Here, we show that APC is required for ribbon size heterogeneity and normal cochlear function. Compared with wild-type littermates, APC conditional knock-out (cKO) mice exhibit decreased auditory brainstem responses. The IHC ribbon size gradient is also perturbed. Whereas the normal-developing IHCs display ribbon size gradients before hearing onset, ribbon sizes are aberrant in APC cKOs from neonatal ages on. Reporter expression studies show that the CaMKII-Cre used to delete the floxed APC gene is present in efferent olivocochlear (OC) neurons, not IHCs or SGNs. APC loss led to increased volumes and numbers of OC inhibitory dopaminergic boutons on neonatal SGN fibers. Our findings identify APC in efferent OC neurons as essential for regulating ribbon heterogeneity, dopaminergic terminal differentiation, and cochlear sensitivity. This APC effect on auditory epithelial cell synapses resembles interneuronal and nerve–muscle synapses, thereby defining a global role for APC in synaptic maturation in diverse cell types. Significance Statement This study identifies novel molecules and cellular interactions that are essential for the proper maturation of afferent ribbon synapses in sensory cells of the inner ear, and for normal hearing. PMID:26085645

  19. Individual differences in cortical connections of somatosensory cortex are associated with parental rearing style in prairie voles (Microtus ochrogaster).

    PubMed

    Seelke, Adele M H; Perkeybile, Allison M; Grunewald, Rebecca; Bales, Karen L; Krubitzer, Leah A

    2016-02-15

    Early-life sensory experiences have a profound effect on brain organization, connectivity, and subsequent behavior. In most mammals, the earliest sensory inputs are delivered to the developing brain through tactile contact with the parents, especially the mother. Prairie voles (Microtus ochrogaster) are monogamous and, like humans, are biparental. Within the normal prairie vole population, both the type and the amount of interactions, particularly tactile contact, that parents have with their offspring vary. The question is whether these early and pervasive differences in tactile stimulation and social experience between parent and offspring are manifest in differences in cortical organization and connectivity. To address this question, we examined the cortical and callosal connections of the primary somatosensory area (S1) in high-contact (HC) and low-contact (LC) offspring using neuroanatomical tracing techniques. Injection sites within S1 were matched so that direct comparisons between these two groups could be made. We observed several important differences between these groups. The first was that HC offspring had a greater density of intrinsic connections within S1 compared with LC offspring. Additionally, HC offspring had a more restricted pattern of ipsilateral connections, whereas LC offspring had dense connections with areas of parietal and frontal cortex that were more widespread. Finally, LC offspring had a broader distribution of callosal connections than HC offspring and a significantly higher percentage of labeled callosal neurons. This study is the first to examine individual differences in cortical connections and suggests that individual differences in cortical connections may be related to natural differences in parental rearing styles associated with tactile contact.

  20. Individual differences in cortical connections of somatosensory cortex are associated with parental rearing style in prairie voles (Microtus ochrogaster).

    PubMed

    Seelke, Adele M H; Perkeybile, Allison M; Grunewald, Rebecca; Bales, Karen L; Krubitzer, Leah A

    2016-02-15

    Early-life sensory experiences have a profound effect on brain organization, connectivity, and subsequent behavior. In most mammals, the earliest sensory inputs are delivered to the developing brain through tactile contact with the parents, especially the mother. Prairie voles (Microtus ochrogaster) are monogamous and, like humans, are biparental. Within the normal prairie vole population, both the type and the amount of interactions, particularly tactile contact, that parents have with their offspring vary. The question is whether these early and pervasive differences in tactile stimulation and social experience between parent and offspring are manifest in differences in cortical organization and connectivity. To address this question, we examined the cortical and callosal connections of the primary somatosensory area (S1) in high-contact (HC) and low-contact (LC) offspring using neuroanatomical tracing techniques. Injection sites within S1 were matched so that direct comparisons between these two groups could be made. We observed several important differences between these groups. The first was that HC offspring had a greater density of intrinsic connections within S1 compared with LC offspring. Additionally, HC offspring had a more restricted pattern of ipsilateral connections, whereas LC offspring had dense connections with areas of parietal and frontal cortex that were more widespread. Finally, LC offspring had a broader distribution of callosal connections than HC offspring and a significantly higher percentage of labeled callosal neurons. This study is the first to examine individual differences in cortical connections and suggests that individual differences in cortical connections may be related to natural differences in parental rearing styles associated with tactile contact. PMID:26101098

  1. Diffusion Tensor MR Imaging Evaluation of Callosal Abnormalities in Schizophrenia: A Meta-Analysis

    PubMed Central

    Zhuo, Chuanjun; Liu, Mei; Wang, Lina; Tian, Hongjun; Tang, Jinsong

    2016-01-01

    Widespread white matter (WM) abnormalities have been found in patients with schizophrenia. Corpus callosum (CC) is the key area that connects the left and right brain hemispheres. However, the results of studies considering different subregions of the CC as regions of interest in patients with schizophrenia have been inconsistent. To obtain a more consistent evaluation of the diffusion characteristics change of the corpus callosum (CC) related to schizophrenia. A meta-analysis involving fractional anisotropy (FA) values in the CC of 729 schizophrenic subjects and 682 healthy controls from 22 studies was conducted. Overall FA values in the CC of the schizophrenic group were less than that of the healthy control group [weighted mean difference (WMD) = -0.021,P< 0.001]. So were the FA values in the genus region (WMD = -0.019, P< 0.001) and the splenium region (WMD = -0.020, P< 0.001) of the CC respectively. The FA reduction was also significant in subjects with chronic schizophrenia (WMD = -0.032, P< 0.001) and first-episode schizophrenia (WMD = -0.014, P = 0.001). In present study, we demonstrated an overall FA decrease in the CC of schizophrenic patients. In the two subgroup analyses of the genu vs splenium region and chronic vs first-episode schizophrenia, the decrease of all groups was significant. Further studies with more homogenous populations and standardized DTI protocols are needed to confirm and extend these findings. PMID:27536773

  2. Diffusion Tensor MR Imaging Evaluation of Callosal Abnormalities in Schizophrenia: A Meta-Analysis.

    PubMed

    Zhuo, Chuanjun; Liu, Mei; Wang, Lina; Tian, Hongjun; Tang, Jinsong

    2016-01-01

    Widespread white matter (WM) abnormalities have been found in patients with schizophrenia. Corpus callosum (CC) is the key area that connects the left and right brain hemispheres. However, the results of studies considering different subregions of the CC as regions of interest in patients with schizophrenia have been inconsistent. To obtain a more consistent evaluation of the diffusion characteristics change of the corpus callosum (CC) related to schizophrenia. A meta-analysis involving fractional anisotropy (FA) values in the CC of 729 schizophrenic subjects and 682 healthy controls from 22 studies was conducted. Overall FA values in the CC of the schizophrenic group were less than that of the healthy control group [weighted mean difference (WMD) = -0.021,P< 0.001]. So were the FA values in the genus region (WMD = -0.019, P< 0.001) and the splenium region (WMD = -0.020, P< 0.001) of the CC respectively. The FA reduction was also significant in subjects with chronic schizophrenia (WMD = -0.032, P< 0.001) and first-episode schizophrenia (WMD = -0.014, P = 0.001). In present study, we demonstrated an overall FA decrease in the CC of schizophrenic patients. In the two subgroup analyses of the genu vs splenium region and chronic vs first-episode schizophrenia, the decrease of all groups was significant. Further studies with more homogenous populations and standardized DTI protocols are needed to confirm and extend these findings. PMID:27536773

  3. Down-regulation of the glucan synthase-like 6 gene (HvGsl6) in barley leads to decreased callose accumulation and increased cell wall penetration by Blumeria graminis f. sp. hordei.

    PubMed

    Chowdhury, Jamil; Schober, Michael S; Shirley, Neil J; Singh, Rohan R; Jacobs, Andrew K; Douchkov, Dimitar; Schweizer, Patrick; Fincher, Geoffrey B; Burton, Rachel A; Little, Alan

    2016-10-01

    The recent characterization of the polysaccharide composition of papillae deposited at the barley cell wall during infection by the powdery mildew pathogen, Blumeria graminis f. sp. hordei (Bgh), has provided new targets for the generation of enhanced disease resistance. The role of callose in papilla-based penetration resistance of crop species is largely unknown because the genes involved in the observed callose accumulation have not been identified unequivocally. We have employed both comparative and functional genomics approaches to identify the functional orthologue of AtGsl5 in the barley genome. HvGsl6 (the barley glucan synthase-like 6 gene), which has the highest sequence identity to AtGsl5, is the only Bgh-induced gene among the HvGsls examined in this study. Through double-stranded RNA interference (dsRNAi)-mediated silencing of HvGsl6, we have shown that the down-regulation of HvGsl6 is associated with a lower accumulation of papillary and wound callose and a higher susceptibility to penetration of the papillae by Bgh, compared with control lines. The results indicate that the HvGsl6 gene is a functional orthologue of AtGsl5 and is involved in papillary callose accumulation in barley. The increased susceptibility of HvGsl6 dsRNAi transgenic lines to infection indicates that callose positively contributes to the barley fungal penetration resistance mechanism.

  4. Medial vestibular connections with the hypocretin (orexin) system

    NASA Technical Reports Server (NTRS)

    Horowitz, Seth S.; Blanchard, Jane; Morin, Lawrence P.

    2005-01-01

    The mammalian medial vestibular nucleus (MVe) receives input from all vestibular endorgans and provides extensive projections to the central nervous system. Recent studies have demonstrated projections from the MVe to the circadian rhythm system. In addition, there are known projections from the MVe to regions considered to be involved in sleep and arousal. In this study, afferent and efferent subcortical connectivity of the medial vestibular nucleus of the golden hamster (Mesocricetus auratus) was evaluated using cholera toxin subunit-B (retrograde), Phaseolus vulgaris leucoagglutinin (anterograde), and pseudorabies virus (transneuronal retrograde) tract-tracing techniques. The results demonstrate MVe connections with regions mediating visuomotor and postural control, as previously observed in other mammals. The data also identify extensive projections from the MVe to regions mediating arousal and sleep-related functions, most of which receive immunohistochemically identified projections from the lateral hypothalamic hypocretin (orexin) neurons. These include the locus coeruleus, dorsal and pedunculopontine tegmental nuclei, dorsal raphe, and lateral preoptic area. The MVe itself receives a projection from hypocretin cells. CTB tracing demonstrated reciprocal connections between the MVe and most brain areas receiving MVe efferents. Virus tracing confirmed and extended the MVe afferent connections identified with CTB and additionally demonstrated transneuronal connectivity with the suprachiasmatic nucleus and the medial habenular nucleus. These anatomical data indicate that the vestibular system has access to a broad array of neural functions not typically associated with visuomotor, balance, or equilibrium, and that the MVe is likely to receive information from many of the same regions to which it projects.

  5. Individual differences in cortical connections of somatosensory cortex are associated with parental rearing style in prairie voles (Microtus ochrogaster)

    PubMed Central

    Seelke, Adele M. H.; Perkeybile, Allison M.; Grunewald, Rebecca; Bales, Karen L.; Krubitzer, Leah A.

    2015-01-01

    Early life sensory experiences have a profound effect on brain organization, connectivity and subsequent behavior. In most mammals, the earliest sensory inputs are delivered to the developing brain through tactile contact with the parents, especially the mother. Prairie voles (Microtus ochrogaster) are monogamous and, like humans, are biparental. Within the normal prairie vole population, both the type and amount of interactions, particularly tactile contact, that parents have with their offspring varies. The question is whether these early and pervasive differences in tactile stimulation and social experience between parent and offspring are manifest in differences in cortical organization and connectivity. To address this question we examined the cortical and callosal connections of the primary somatosensory area (S1) in high contact (HC) and low contact (LC) offspring using neuroanatomical tracing techniques. Injection sites within S1 were matched so that direct comparisons between these two groups could be made. We observed several important differences between these groups. The first was that HC offspring had a greater density of intrinsic connections within S1 compared to LC offspring. The HC offspring had a more restricted pattern of ipsilateral connections while LC offspring had dense connections with areas of parietal and frontal cortex that were more widespread. Finally, LC offspring had a broader distribution of callosal connections than HC offspring and a significantly higher percentage of callosal labeled neurons. To date, this is the first study that examines individual differences in cortical connections and suggests that they may be related to natural differences in parental rearing styles associated with tactile contact. PMID:26101098

  6. The multivesicular body-localized GTPase ARFA1b/1c is important for callose deposition and ROR2 syntaxin-dependent preinvasive basal defense in barley.

    PubMed

    Böhlenius, Henrik; Mørch, Sara M; Godfrey, Dale; Nielsen, Mads E; Thordal-Christensen, Hans

    2010-11-01

    Host cell vesicle traffic is essential for the interplay between plants and microbes. ADP-ribosylation factor (ARF) GTPases are required for vesicle budding, and we studied the role of these enzymes to identify important vesicle transport pathways in the plant-powdery mildew interaction. A combination of transient-induced gene silencing and transient expression of inactive forms of ARF GTPases provided evidence that barley (Hordeum vulgare) ARFA1b/1c function is important for preinvasive penetration resistance against powdery mildew, manifested by formation of a cell wall apposition, named a papilla. Mutant studies indicated that the plasma membrane-localized REQUIRED FOR MLO-SPECIFIED RESISTANCE2 (ROR2) syntaxin, also important for penetration resistance, and ARFA1b/1c function in the same vesicle transport pathway. This was substantiated by a requirement of ARFA1b/1c for ROR2 accumulation in the papilla. ARFA1b/1c is localized to multivesicular bodies, providing a functional link between ROR2 and these organelles in penetration resistance. During Blumeria graminis f sp hordei penetration attempts, ARFA1b/1c-positive multivesicular bodies assemble near the penetration site hours prior to the earliest detection of callose in papillae. Moreover, we showed that ARFA1b/1c is required for callose deposition in papillae and that the papilla structure is established independently of ARFA1b/1c. This raises the possibility that callose is loaded into papillae via multivesicular bodies, rather than being synthesized directly into this cell wall apposition.

  7. How do the medial olivocochlear efferents influence the biomechanics of the outer hair cells and thereby the cochlear amplifier? Simulation results

    NASA Astrophysics Data System (ADS)

    Saremi, Amin; Stenfelt, Stefan; Verhulst, Sarah

    2015-12-01

    The bottom-up signal pathway, which starts from the outer ear and leads to the brain cortices, gives the classic image of the human sound perception. However, there have been growing evidences in the last six decades for existence of a functional descending network whereby the central auditory system can modulate the early auditory processing, in a top-down manner. The medial olivocochlear efferent fibers project from the superior olivary complex at the brainstem into the inner ear. They are linked to the basal poles of the hair cells by forming synaptic cisterns. This descending network can activate nicotinic cholinergic receptors (nAChR) that increase the membrane conductance of the outer hair cells and thereby modify the magnitude of the active force generated inside the cochlea. The aim of the presented work is to quantitatively investigate how the changes in the biomechanics of the outer hair cells, caused by the efferent activation, manipulate the cochlear responses. This is done by means of a frequency-domain biophysical model of the cochlea [12] where the parameters of the model convey physiological interpretations of the human cochlear structures. The simulations manifest that a doubling of the outer hair cell conductance, due to efferent activation, leads to a frequency-dependent gain reduction along the cochlear duct with its highest effect at frequencies between 1 kHz and 3.5 kHz and a maximum of approximately 10 dB gain reduction at 2 kHz. This amount of the gain inhibition and its frequency dependence reasonably agrees with the experimental data recorded from guinea pig, cat and human cochleae where the medial olivococlear efferents had been elicited by broad-band stimuli. The simulations also indicate that the efferent-induced increase of the outer hair cell conductance increases the best frequency of the cochlear responses, in the basal region. The presented simulations quantitatively confirm that activation of the medial olivocochlear efferents can

  8. Sr36- and Sr5-Mediated Resistance Response to Puccinia graminis f. sp. tritici Is Associated with Callose Deposition in Wheat Guard Cells.

    PubMed

    Wang, X; McCallum, B D; Fetch, T; Bakkeren, G; Saville, B J

    2015-06-01

    Race-specific resistance of wheat to Puccinia graminis f. sp. tritici is primarily posthaustorial and often involves the induction of a hypersensitive response (HR). The aim of this study was to investigate host defense responses induced in interactions between P. graminis f. sp. tritici races and wheat lines carrying different race-specific stem rust resistance (Sr) genes. In incompatible interactions between wheat lines carrying Sr36 in three genetic backgrounds (LMPG, Prelude, or W2691) and avirulent P. graminis f. sp. tritici races MCCFC or RCCDM, callose accumulated within 24 h in wheat guard cells contacted by a P. graminis f. sp. tritici appressorium, and P. graminis f. sp. tritici ingress was inhibited following appressorium formation. Accordingly, the expression of transcripts encoding a callose synthase increased in the incompatible interaction between LMPG-Sr36 and avirulent P. graminis f. sp. tritici race MCCFC. Furthermore, the inhibition of callose synthesis through the infiltration of 2-deoxy-D-glucose (DDG) increased the ability of P. graminis f. sp. tritici race MCCFC to infect LMPG-Sr36. A similar induction of callose deposition in wheat guard cells was also observed within 24 h after inoculation (hai) with avirulent P. graminis f. sp. tritici race HKCJC on LMPG-Sr5 plants. In contrast, this defense response was not induced in incompatible interactions involving Sr6, Sr24, or Sr30. Instead, the induction of an HR and cellular lignification were noted. The manifestation of the HR and cellular lignification was induced earlier (24 hai) and was more extensive in the resistance response mediated by Sr6 compared with those mediated by Sr24 or Sr30. These results indicate that the resistance mediated by Sr36 is similar to that mediated by Sr5 but different from those triggered by Sr6, Sr24, or Sr30. Resistance responses mediated by Sr5 and Sr36 are prehaustorial, and are a result of very rapid recognition of molecules derived from avirulent isolates of

  9. Role of Efferent Sympathoadrenal Effects in Cooling-Induced Hemodynamic Perturbations in Rats: An Investigation by Spectrum Analysis.

    PubMed

    Liu, Yia-Ping; Lin, Yi-Hsien; Lin, Chen-Cheng; Lin, Yu-Chieh; Chen, Yu-Chun; Lee, Po-Lei; Tung, Che-Se

    2015-10-31

    Cold stress may produce hemodynamic perturbations but the underlying mechanisms are still not clear. Spectral analysis was used in this study to explore that sympathoadrenal activation could be involved in mechanisms of hemodynamic perturbations to cooling. Conscious rats after treatment with a control vehicle (saline) compared with withdrawal of sympathetic influences by ganglion blocker hexamethonium (HEX) or chemical sympathectomy guanethidine (GUA) were challenged by stressful cooling as acute immersing all four extremities in ice water (4 ± 2°C) for 10 min. Plasma nitric oxide (NO) and the appearance of Dichroitic notch (DN) were measured in comparison between treatment groups throughout the experimental course. Hemodynamic indices were telemetrically monitored, and variability of blood pressure and heart rate (BPV; HRV) were assessed over a range of frequencies: very-low frequency (VLF: 0.02-0.2 Hz), low frequency (LF: 0.2-0.6 Hz), high frequency (HF: 0.6-3 Hz), normalized (n)LF, nHF, ratio LF/HF of HRV (LF/HF(HRV)), and total power (TP: ≤3 Hz). Results showed that the concomitant reciprocal changes of spectral powers existed between frequencies of BPV and HRV to the stressful cooling (i.e. VLF(BPV) versus VLF(HRV), LF(BPV) versus LF(HRV), and nLF(BPV) versus nLF(HRV)) which contribute to the underlying mechanisms of sympathetic efferent influences and myogenic cardiovascular responsiveness. Furthermore, compared with the control vehicle in the stressful cooling, HEX restrained the increase of the pressor, tachycardia and VLF(BPV), except that VLF(HRV) was reduced. GUA abolished pressor, however, restrained the increase of the tachycardia, VLF(BPV) and LF(BPV). In addition, GUA reversed the downward tendency of nLF(BPV) into an upward tendency and attenuated both nLF(HRV) and LF/HF(HRV). DN was virtually undetectable after HEX management but was apparently noticeable after GUA management. Finally, the increase of plasma NO after cooling was diminished

  10. Role of Efferent Sympathoadrenal Effects in Cooling-Induced Hemodynamic Perturbations in Rats: An Investigation by Spectrum Analysis.

    PubMed

    Liu, Yia-Ping; Lin, Yi-Hsien; Lin, Chen-Cheng; Lin, Yu-Chieh; Chen, Yu-Chun; Lee, Po-Lei; Tung, Che-Se

    2015-10-31

    Cold stress may produce hemodynamic perturbations but the underlying mechanisms are still not clear. Spectral analysis was used in this study to explore that sympathoadrenal activation could be involved in mechanisms of hemodynamic perturbations to cooling. Conscious rats after treatment with a control vehicle (saline) compared with withdrawal of sympathetic influences by ganglion blocker hexamethonium (HEX) or chemical sympathectomy guanethidine (GUA) were challenged by stressful cooling as acute immersing all four extremities in ice water (4 ± 2°C) for 10 min. Plasma nitric oxide (NO) and the appearance of Dichroitic notch (DN) were measured in comparison between treatment groups throughout the experimental course. Hemodynamic indices were telemetrically monitored, and variability of blood pressure and heart rate (BPV; HRV) were assessed over a range of frequencies: very-low frequency (VLF: 0.02-0.2 Hz), low frequency (LF: 0.2-0.6 Hz), high frequency (HF: 0.6-3 Hz), normalized (n)LF, nHF, ratio LF/HF of HRV (LF/HF(HRV)), and total power (TP: ≤3 Hz). Results showed that the concomitant reciprocal changes of spectral powers existed between frequencies of BPV and HRV to the stressful cooling (i.e. VLF(BPV) versus VLF(HRV), LF(BPV) versus LF(HRV), and nLF(BPV) versus nLF(HRV)) which contribute to the underlying mechanisms of sympathetic efferent influences and myogenic cardiovascular responsiveness. Furthermore, compared with the control vehicle in the stressful cooling, HEX restrained the increase of the pressor, tachycardia and VLF(BPV), except that VLF(HRV) was reduced. GUA abolished pressor, however, restrained the increase of the tachycardia, VLF(BPV) and LF(BPV). In addition, GUA reversed the downward tendency of nLF(BPV) into an upward tendency and attenuated both nLF(HRV) and LF/HF(HRV). DN was virtually undetectable after HEX management but was apparently noticeable after GUA management. Finally, the increase of plasma NO after cooling was diminished

  11. Spontaneous efferent activity in branches of the vagus nerve controlling heart rate and ventilation in the dogfish.

    PubMed

    Barrett, D J; Taylor, E W

    1985-07-01

    Efferent activity was recorded from cranial nerves in the decerebrate dogfish (Scyliorhinus canicula) before and after injection of paralysing drugs. The recordings were made from the mandibular (Vth) and glossopharyngeal (IXth) nerves and the branchial (respiratory) and cardiac branches of the vagus (Xth) nerve. All the respiratory branches (Vth, IXth and Xth) and both cardiac branches fired rhythmic bursts of activity, synchronous with ventilation, which continued (at a higher rate) following paralysis, indicating that they originated in the CNS rather than arising reflexly from stimulation of pharyngeal mechanoreceptors. A burst of activity in the Vth nerve was followed by a burst in the IXth then, after a 30-ms delay, simultaneous bursts in the three respiratory branches of the Xth. The bursts in the branchial cardiac branches had a fixed phase relationship with activity in the respiratory branches, the onset of each burst preceding that in the immediately adjacent branch (branchial III), whereas the bursts in the visceral cardiac branches had a variable phase relationship with all other branches. The branchial cardiac branches alone contained units which fired sporadically between the bursts and increased their rate of firing during hypoxia. Both the bursting and non-bursting units responded to mechanical stimulation of the gill area. Separate oscillatory inputs driving the Vth, IXth and Xth respiratory motoneurones and an excitatory input to the bursting cardiac vagal motoneurones from expiratory motoneurones or the respiratory rhythm generator are implied by these relationships. The sporadically firing units in the branchial cardiac nerves clearly receive non-oscillatory inputs.

  12. Diencephalic and mesencephalic efferents of the medial prefrontal cortex in the rat: electrophysiological evidence for the existence of branched axons.

    PubMed

    Thierry, A M; Chevalier, G; Ferron, A; Glowinski, J

    1983-01-01

    Efferents originating from the rat medial prefrontal cortex and projecting to diencephalic and mesencephalic structures were analyzed electrophysiologically. The antidromic activation technique was used in order to identify cortical neurons which innervate the medio-dorsal nucleus of the thalamus (MD), lateral habenula, ventro-medial mesencephalic tegmentum (VMT), substantia nigra (SN), superior colliculus (SC) and central gray (CG). Corresponding cortical neurons, found mainly in layers V and VI, were distributed in the rostro-caudal extension of the medial prefrontal cortex. Their conduction velocities were relatively slow and ranged between 0.4 and 5.5 m/s. The reciprocal collision test allowed us to determine whether a given cortical neuron innervated only one structure or whether it sent axon collaterals to other subcortical areas. Twelve patterns of axonal branching were established: MD-VMT, MD-SN, MD-SC, VMT-SN, VMT-SC, VMT-CG, SN-SC, habenula-VMT, habenula-CG, MD-SN-SC, VMT-SN-SC and VMT-habenula-CG. Finally, it was estimated that a large proportion of the prefrontal cells which project to a given subcortical structure also innervate one or two other subcortical areas. Results are discussed in the light of anatomical data and their functional significance.

  13. Time-frequency analysis of stimulus frequency otoacoustic emissions and their changes with efferent stimulation in guinea pigs

    NASA Astrophysics Data System (ADS)

    Berezina-Greene, Maria A.; Guinan, John J.

    2015-12-01

    To aid in understanding their origin, stimulus frequency otoacoustic emissions (SFOAEs) were measured at a series of tone frequencies using the suppression method, both with and without stimulation of medial olivocochlear (MOC) efferents, in anesthetized guinea pigs. Time-frequency analysis showed SFOAE energy peaks in 1-3 delay components throughout the measured frequency range (0.5-12 kHz). One component's delay usually coincided with the phase-gradient delay. When multiple delay components were present, they were usually near SFOAE dips. Below 2 kHz, SFOAE delays were shorter than predicted from mechanical measurements. With MOC stimulation, SFOAE amplitude was decreased at most frequencies, but was sometimes enhanced, and all SFOAE delay components were affected. The MOC effects and an analysis of model data suggest that the multiple SFOAE delay components arise at the edges of the traveling-wave peak, not far basal of the peak. Comparisons with published guinea-pig neural data suggest that the short latencies of low-frequency SFOAEs may arise from coherent reflection from an organ-of-Corti motion that has a shorter group delay than the traveling wave.

  14. Differential action for ethanol on baroreceptor reflex control of heart rate and sympathetic efferent discharge in rats

    SciTech Connect

    Xin, Z.; Abdel-Rahman, A.R.A.; Wooles, W.R.

    1988-01-01

    The acute effects of ethanol (0.33, 0.66, or 1 g/kg) on baroreflex control of heart rate (HR) and sympathetic efferent discharge (SED) were investigated in rats. The two higher doses of ethanol caused a progressive and significant increase in baseline SED and a slight increase in HR. The findings suggest that the sensitivity of the reflex control of SED was preserved whereas that of HR was impaired after acute ethanol administration. Since these findings were obtained in the same animals, the data suggest that acute ethanol has a differential action on reflex control of SED and HR. Further, the significant increase in SED after moderate and high doses of ethanol suggests an increased central sympathetic tone as recordings were made from preganglionic nerve fibers (splanchnic nerve). The absence of an increase in baseline MAP, in spite of a significant increase in baseline SED following acute ethanol injection, could be explained, at least in part, by an ethanol-evoked reduction in pressor responsiveness to phenylephrine, an ..cap alpha..-adrenergic agonist.

  15. Selective inhibition of PDE4 in Wistar rats can lead to dilatation in testis, efferent ducts, and epididymis and subsequent formation of sperm granulomas.

    PubMed

    Heuser, Anke; Mecklenburg, Lars; Ockert, Deborah; Kohler, Manfred; Kemkowski, Jörg

    2013-01-01

    Testicular tubular dilatation and degeneration and epididymal sperm granulomas were frequently seen in 4-week toxicity studies using different phosphodiesterase-4 (PDE4) inhibitors in Wistar rats, including the prototypic PDE4 inhibitor BYK169171. To investigate the pathogenesis of testicular and epididymal lesions, a time course study with BYK169171 was conducted with sequential necropsies after 7, 14, 21, and 28 days of treatment. After 7 days, a dilatation of efferent ducts and of the initial segment of the epididymis and a subacute interstitial inflammation were seen followed by a diffuse dilatation of seminiferous tubules in the testis. Dilatation and inflammation were most pronounced after 14 days. Single animals also exhibited vascular necrosis in the inflamed interstitium. Although dilatation decreased later in the study, the incidence and severity of tubular degeneration increased from 14 days onward. Sperm granulomas developed in efferent ducts and in the caput and cauda of the epididymis after 14 days. Our results demonstrate a clear time course of PDE4 inhibition-induced lesions, with dilatation preceding sperm granuloma formation. We conclude that the most likely mechanism of toxicity is a disturbance of fluid homeostasis in efferent and epididymal ducts resulting in abnormal luminal fluid and sperm contents, epithelial damage at specific sites of the excurrent duct system, sperm leakage, and granuloma formation.

  16. CYCLIN-DEPENDENT KINASE G1 is associated with the spliceosome to regulate CALLOSE SYNTHASE5 splicing and pollen wall formation in Arabidopsis.

    PubMed

    Huang, Xue-Yong; Niu, Jin; Sun, Ming-Xi; Zhu, Jun; Gao, Ju-Fang; Yang, Jun; Zhou, Que; Yang, Zhong-Nan

    2013-02-01

    Arabidopsis thaliana CYCLIN-DEPEDENT KINASE G1 (CDKG1) belongs to the family of cyclin-dependent protein kinases that were originally characterized as cell cycle regulators in eukaryotes. Here, we report that CDKG1 regulates pre-mRNA splicing of CALLOSE SYNTHASE5 (CalS5) and, therefore, pollen wall formation. The knockout mutant cdkg1 exhibits reduced male fertility with impaired callose synthesis and abnormal pollen wall formation. The sixth intron in CalS5 pre-mRNA, a rare type of intron with a GC 5' splice site, is abnormally spliced in cdkg1. RNA immunoprecipitation analysis suggests that CDKG1 is associated with this intron. CDKG1 contains N-terminal Ser/Arg (RS) motifs and interacts with splicing factor Arginine/Serine-Rich Zinc Knuckle-Containing Protein33 (RSZ33) through its RS region to regulate proper splicing. CDKG1 and RS-containing Zinc Finger Protein22 (SRZ22), a splicing factor interacting with RSZ33 and U1 small nuclear ribonucleoprotein particle (snRNP) component U1-70k, colocalize in nuclear speckles and reside in the same complex. We propose that CDKG1 is recruited to U1 snRNP through RSZ33 to facilitate the splicing of the sixth intron of CalS5.

  17. Rice UDP-glucose pyrophosphorylase1 is essential for pollen callose deposition and its cosuppression results in a new type of thermosensitive genic male sterility.

    PubMed

    Chen, Rongzhi; Zhao, Xiao; Shao, Zhe; Wei, Zhe; Wang, Yuanyuan; Zhu, Lili; Zhao, Jie; Sun, Mengxiang; He, Ruifeng; He, Guangcun

    2007-03-01

    UDP-glucose pyrophosphorylase (UGPase) catalyzes the reversible production of glucose-1-phosphate and UTP to UDP-glucose and pyrophosphate. The rice (Oryza sativa) genome contains two homologous UGPase genes, Ugp1 and Ugp2. We report a functional characterization of rice Ugp1, which is expressed throughout the plant, with highest expression in florets, especially in pollen during anther development. Ugp1 silencing by RNA interference or cosuppression results in male sterility. Expressing a double-stranded RNA interference construct in Ugp1-RI plants resulted in complete suppression of both Ugp1 and Ugp2, together with various pleiotropic developmental abnormalities, suggesting that UGPase plays critical roles in plant growth and development. More importantly, Ugp1-cosuppressing plants contained unprocessed intron-containing primary transcripts derived from transcription of the overexpression construct. These aberrant transcripts undergo temperature-sensitive splicing in florets, leading to a novel thermosensitive genic male sterility. Pollen mother cells (PMCs) of Ugp1-silenced plants appeared normal before meiosis, but during meiosis, normal callose deposition was disrupted. Consequently, the PMCs began to degenerate at the early meiosis stage, eventually resulting in complete pollen collapse. In addition, the degeneration of the tapetum and middle layer was inhibited. These results demonstrate that rice Ugp1 is required for callose deposition during PMC meiosis and bridges the apoplastic unloading pathway and pollen development. PMID:17400897

  18. CYCLIN-DEPENDENT KINASE G1 Is Associated with the Spliceosome to Regulate CALLOSE SYNTHASE5 Splicing and Pollen Wall Formation in Arabidopsis[C][W][OA

    PubMed Central

    Huang, Xue-Yong; Niu, Jin; Sun, Ming-Xi; Zhu, Jun; Gao, Ju-Fang; Yang, Jun; Zhou, Que; Yang, Zhong-Nan

    2013-01-01

    Arabidopsis thaliana CYCLIN-DEPEDENT KINASE G1 (CDKG1) belongs to the family of cyclin-dependent protein kinases that were originally characterized as cell cycle regulators in eukaryotes. Here, we report that CDKG1 regulates pre-mRNA splicing of CALLOSE SYNTHASE5 (CalS5) and, therefore, pollen wall formation. The knockout mutant cdkg1 exhibits reduced male fertility with impaired callose synthesis and abnormal pollen wall formation. The sixth intron in CalS5 pre-mRNA, a rare type of intron with a GC 5′ splice site, is abnormally spliced in cdkg1. RNA immunoprecipitation analysis suggests that CDKG1 is associated with this intron. CDKG1 contains N-terminal Ser/Arg (RS) motifs and interacts with splicing factor Arginine/Serine-Rich Zinc Knuckle-Containing Protein33 (RSZ33) through its RS region to regulate proper splicing. CDKG1 and RS-containing Zinc Finger Protein22 (SRZ22), a splicing factor interacting with RSZ33 and U1 small nuclear ribonucleoprotein particle (snRNP) component U1-70k, colocalize in nuclear speckles and reside in the same complex. We propose that CDKG1 is recruited to U1 snRNP through RSZ33 to facilitate the splicing of the sixth intron of CalS5. PMID:23404887

  19. The basis of vagal efferent control of heart rate in a neotropical fish, the pacu, Piaractus mesopotamicus.

    PubMed

    Taylor, E W; Leite, C A C; Florindo, L H; Beläo, T; Rantin, F T

    2009-04-01

    The role of the parasympathetic nervous system, operating via the vagus nerve, in determining heart rate (f(H)) and cardiorespiratory interactions was investigated in the neotropical fish Piaractus mesopotamicus. Motor nuclei of branches of cranial nerves VII, IX and X, supplying respiratory muscles and the heart, have an overlapping distribution in the brainstem, while the Vth motor nucleus is more rostrally located. Respiration-related efferent activity in the cardiac vagus appeared to entrain the heart to ventilation. Peripheral stimulation of the cardiac vagus with short bursts of electrical stimuli entrained the heart at a ratio of 1:1 over a range of frequencies, both below and sometimes above the intrinsic heart rate. Alternatively, at higher bursting frequencies the induced f(H) was slower than the applied stimulus, being recruited by a whole number fraction (1:2 to 1:6) of the stimulus frequency. These effects indicate that respiration-related changes in f(H) in pacu are under direct, beat-to-beat vagal control. Central burst stimulation of respiratory branches of cranial nerves VII, IX and X also entrained the heart, which implies that cardiorespiratory interactions can be generated reflexly. Central stimulation of the Vth cranial nerve was without effect on heart rate, possibly because its central projections do not overlap with cardiac vagal preganglionic neurons in the brainstem. However, bursts of activity recorded from the cardiac vagus were concurrent with bursts in this nerve, suggesting that cardiorespiratory interactions can arise within the CNS, possibly by irradiation from a central respiratory pattern generator, when respiratory drive is high. PMID:19282487

  20. Schizophrenia, abnormal connection, and brain evolution.

    PubMed

    Randall, P L

    1983-03-01

    Abnormalities of functional connection between specialized areas in the human brain may underlie the symptoms which constitute the schizophrenia syndrome. Callosal and intrahemispheric fibres may be equally involved. The clinical emergence of symptoms in the later stages of brain maturation may be dependent on myelination of these fibre groups, both of which have extended myelination cycles. Ontogenetically earlier variants of the same mechanism could theoretically result in dyslexia and the syndromes of Kanner and Gilles de la Tourette. As new and unique extensions of specialized function emerge within the evolving brain, biological trial and error of connection both within and between them may produce individuals possessing phylogenetically advanced abilities, or equally, others possessing a wide range of abnormalities including those which comprise the schizophrenia syndrome. A dormant phenotypic potential for schizophrenia may exist in individuals who never develop symptoms during the course of a lifetime though some of these may become clinically apparent under the influence of various precipitating factors. It is concluded that abnormal functional connection and its normal and "supernormal" counterparts may be natural, essential, and inevitable consequences of brain evolution, and that this may have been so throughout the history of vertebrate brain evolution.

  1. A Mammalian Conserved Element Derived from SINE Displays Enhancer Properties Recapitulating Satb2 Expression in Early-Born Callosal Projection Neurons

    PubMed Central

    Nakanishi, Akiko; Sasaki, Takeshi; Yan, Kuo; Tarabykin, Victor; Vigier, Lisa; Sumiyama, Kenta; Hirakawa, Mika; Nishihara, Hidenori; Pierani, Alessandra; Okada, Norihiro

    2011-01-01

    Short interspersed repetitive elements (SINEs) are highly repeated sequences that account for a significant proportion of many eukaryotic genomes and are usually considered “junk DNA”. However, we previously discovered that many AmnSINE1 loci are evolutionarily conserved across mammalian genomes, suggesting that they may have acquired significant functions involved in controlling mammalian-specific traits. Notably, we identified the AS021 SINE locus, located 390 kbp upstream of Satb2. Using transgenic mice, we showed that this SINE displays specific enhancer activity in the developing cerebral cortex. The transcription factor Satb2 is expressed by cortical neurons extending axons through the corpus callosum and is a determinant of callosal versus subcortical projection. Mouse mutants reveal a crucial function for Sabt2 in corpus callosum formation. In this study, we compared the enhancer activity of the AS021 locus with Satb2 expression during telencephalic development in the mouse. First, we showed that the AS021 enhancer is specifically activated in early-born Satb2+ neurons. Second, we demonstrated that the activity of the AS021 enhancer recapitulates the expression of Satb2 at later embryonic and postnatal stages in deep-layer but not superficial-layer neurons, suggesting the possibility that the expression of Satb2 in these two subpopulations of cortical neurons is under genetically distinct transcriptional control. Third, we showed that the AS021 enhancer is activated in neurons projecting through the corpus callosum, as described for Satb2+ neurons. Notably, AS021 drives specific expression in axons crossing through the ventral (TAG1−/NPY+) portion of the corpus callosum, confirming that it is active in a subpopulation of callosal neurons. These data suggest that exaptation of the AS021 SINE locus might be involved in enhancement of Satb2 expression, leading to the establishment of interhemispheric communication via the corpus callosum, a eutherian

  2. Contribution of Fibroblast and Mast Cell (Afferent) and Tumor (Efferent) IL-6 Effects within the Tumor Microenvironment.

    PubMed

    Hugo, Honor J; Lebret, Stephanie; Tomaskovic-Crook, Eva; Ahmed, Nuzhat; Blick, Tony; Newgreen, Donald F; Thompson, Erik W; Ackland, M Leigh

    2012-04-01

    versus Luminal molecular/phenotypic groupings of breast cancer cell lines. Finally, we discuss how afferent and efferent IL-6 pathways may participate in a positive feedback cycle to dictate tumor progression.

  3. Innervation of the cavernous body of the human efferent tear ducts and function in tear outflow mechanism

    PubMed Central

    PAULSEN, FRIEDRICH; HALLMANN, UTA; PAULSEN, JENS; THALE, ANDREAS

    2000-01-01

    The lacrimal sac and nasolacrimal duct are surrounded by a wide cavernous system of veins and arteries comparable to a cavernous body. The present study aimed to demonstrate the ultrastructure of the nervous tissue and the localisation of neuropeptides involved in the innervation of the cavernous body, a topic not previously investigated. Different S-100 protein antisera, neuronal markers (neuron-specific enolase, anti-200 kDa neurofilament), neuropeptides (substance P, neuropeptide Y, calcitonin gene-related peptide, vasoactive intestinal polypeptide) and the neuronal enzyme tyrosine hydroxylase were used to demonstrate the distribution pattern of the nervous tissue. The ultrastructure of the innervating nerve fibres was also examined by means of standard transmission electron microscopy. The cavernous body contained specialised arteries and veins known as barrier arteries, capacitance veins, and throttle veins. Perivascularly, the tissue was rich in myelinated and unmyelinated nerve fibres in a plexus-like network. Small seromucous glands found in the region of the fundus of the lacrimal sac were contacted by nerve fibres forming a plexus around their alveoli. Many nerve fibres were positive for S-100 protein (S 100), neuron-specific enolase (NSE), anti-200 kDa neurofilament (RT 97), calcitonin gene-related peptide (CGRP), substance P (SP), tyrosine hydroxylase (TH), and neuropeptide Y (NPY). Vasoactive intestinal polypeptide (VIP) immunoreactivity was only demonstrated adjacent to the seromucous glands. Both the density of nerve fibres as well as the presence of various neuropeptides emphasises the neural control of the cavernous body of the human efferent tear ducts. By means of this innervation, the specialised blood vessels permit regulation of blood flow by opening and closing the lumen of the lacrimal passage as effected by the engorgement and subsidence of the cavernous body, at the same time regulating tear outflow. Related functions such as a role in the

  4. Experimental studies of gastric dysfunction in motion sickness: The effect of gastric and vestibular stimulation on the vagal and splanchnic gastric efferents

    NASA Technical Reports Server (NTRS)

    Niijima, A.; Jiang, Z. Y.; Daunton, Nancy G.; Fox, Robert A.

    1991-01-01

    The experiments were conducted in anaesthetized rats. In the first part of the experiments, the effect of CuSO4 on the afferent activity in the gastric branch of the vagus nerve was investigated. Gastric perfusion of CuSO4 solution (0.04 percent and 0.08 percent) provoked an increase in afferent activity. In the second part of the experiments, the reflex effects of gastric perfusion of CuSO4 solution, repetitive stimulation of the gastric vagus nerve, and caloric stimulation of the right vestibular apparatus (5-18 C water) on gastric autonomic outflow were investigated. The results of these experiments showed that these three different types of stimulation caused an inhibition in efferent activity of the gastric vagus nerve and a slight activation of the splanchnic gastric efferents. The summation of the effect of each stimulation was also observed. These results, therefore, provide evidence for a possible integrative inhibitory function of the vagal gastric center as well as an excitatory function of gastric sympathetic motoneurons in relation to motion sickness.

  5. White Matter Compromise of Callosal and Subcortical Fiber Tracts in Children with Autism Spectrum Disorder: A Diffusion Tensor Imaging Study

    ERIC Educational Resources Information Center

    Shukla, Dinesh K.; Keehn, Brandon; Lincoln, Alan J.; Muller, Ralph-Axel

    2010-01-01

    Objective: Autism spectrum disorder (ASD) is increasingly viewed as a disorder of functional networks, highlighting the importance of investigating white matter and interregional connectivity. We used diffusion tensor imaging (DTI) to examine white matter integrity for the whole brain and for corpus callosum, internal capsule, and middle…

  6. Altered effective connectivity within default mode network in major depression disorder

    NASA Astrophysics Data System (ADS)

    Li, Liang; Li, Baojuan; Bai, Yuanhan; Wang, Huaning; Zhang, Linchuan; Cui, Longbiao; Lu, Hongbing

    2016-03-01

    Understanding the neural basis of Major Depressive Disorder (MDD) is important for the diagnosis and treatment of this mental disorder. The default mode network (DMN) is considered to be highly involved in the MDD. To find directed interaction between DMN regions associated with the development of MDD, the effective connectivity within the DMN of the MDD patients and matched healthy controls was estimated by using a recently developed spectral dynamic causal modeling. Sixteen patients with MDD and sixteen matched healthy control subjects were included in this study. While the control group underwent the resting state fMRI scan just once, all patients underwent resting state fMRI scans before and after two months' treatment. The spectral dynamic causal modeling was used to estimate directed connections between four DMN nodes. Statistical analysis on connection strengths indicated that efferent connections from the medial frontal cortex (MFC) to posterior cingulate cortex (PCC) and to right parietal cortex (RPC) were significant higher in pretreatment MDD patients than those of the control group. After two-month treatment, the efferent connections from the MFC decreased significantly, while those from the left parietal cortex (LPC) to MFC, PCC and RPC showed a significant increase. These findings suggest that the MFC may play an important role for inhibitory conditioning of the DMN, which was disrupted in MDD patients. It also indicates that disrupted suppressive function of the MFC could be effectively restored after two-month treatment.

  7. Connected Traveler

    SciTech Connect

    Schroeder, Alex

    2015-11-01

    The Connected Traveler project is a multi-disciplinary undertaking that seeks to validate potential for transformative transportation system energy savings by incentivizing efficient traveler behavior. This poster outlines various aspects of the Connected Traveler project, including market opportunity, understanding traveler behavior and decision-making, automation and connectivity, and a projected timeline for Connected Traveler's key milestones.

  8. The PTI1-like kinase ZmPti1a from maize (Zea mays L.) co-localizes with callose at the plasma membrane of pollen and facilitates a competitive advantage to the male gametophyte

    PubMed Central

    Herrmann, Markus M; Pinto, Sheena; Kluth, Jantjeline; Wienand, Udo; Lorbiecke, René

    2006-01-01

    Background The tomato kinase Pto confers resistance to bacterial speck disease caused by Pseudomonas syringae pv. tomato in a gene for gene manner. Upon recognition of specific avirulence factors the Pto kinase activates multiple signal transduction pathways culminating in induction of pathogen defense. The soluble cytoplasmic serine/threonine kinase Pti1 is one target of Pto phosphorylation and is involved in the hypersensitive response (HR) reaction. However, a clear role of Pti1 in plant pathogen resistance is uncertain. So far, no Pti1 homologues from monocotyledonous species have been studied. Results Here we report the identification and molecular analysis of four Pti1-like kinases from maize (ZmPti1a, -b, -c, -d). These kinase genes showed tissue-specific expression and their corresponding proteins were targeted to different cellular compartments. Sequence similarity, expression pattern and cellular localization of ZmPti1b suggested that this gene is a putative orthologue of Pti1 from tomato. In contrast, ZmPti1a was specifically expressed in pollen and sequestered to the plasma membrane, evidently owing to N-terminal modification by myristoylation and/or S-acylation. The ZmPti1a:GFP fusion protein was not evenly distributed at the pollen plasma membrane but accumulated as an annulus-like structure which co-localized with callose (1,3-β-glucan) deposition. In addition, co-localization of ZmPti1a and callose was observed during stages of pollen mitosis I and pollen tube germination. Maize plants in which ZmPti1a expression was silenced by RNA interference (RNAi) produced pollen with decreased competitive ability. Hence, our data provide evidence that ZmPti1a plays an important part in a signalling pathway that accelerates pollen performance and male fitness. Conclusion ZmPti1a from maize is involved in pollen-specific processes during the progamic phase of reproduction, probably in crucial signalling processes associated with regions of callose deposition

  9. Septal and amygdalar efferents to the hypothalamus which facilitate hypothalamically elicited intraspecific aggression and associated hissing in the cat. An autoradiographic study.

    PubMed

    Stoddard-Apter, S L; MacDonnell, M F

    1980-07-01

    Septal and amygdalar sites were identified which facilitated hypothalamically elicited intraspecific agression and associated hissing in cats. Tritiated proline was injected into facilitatory sites through a Hamilton syringe modified to serve as an electrode. Efferents from septal or amygdalar facilitatory sites were traced to the hypothalamus by means of autoradiography. Amygdalar facilitatory sites projected primarily to the core and capsule of the ventromedial nucleus of the hypothalamus (VMH), while septal facilitatory sites projected only lightly to the VMH. Common to all septal facilitatory sites, and not previously reported, was a distinct and considerable projection to the medial hypothalamus, in association with the paraventricular and dorsomedial nuclei. The means by which septal and amygdalar sites may act to facilitate hypothalamically elicited intraspecific aggression are discussed. PMID:7189686

  10. Central command: control of cardiac sympathetic and vagal efferent nerve activity and the arterial baroreflex during spontaneous motor behaviour in animals.

    PubMed

    Matsukawa, Kanji

    2012-01-01

    Feedforward control by higher brain centres (termed central command) plays a role in the autonomic regulation of the cardiovascular system during exercise. Over the past 20 years, workers in our laboratory have used the precollicular-premammillary decerebrate animal model to identify the neural circuitry involved in the CNS control of cardiac autonomic outflow and arterial baroreflex function. Contrary to the traditional idea that vagal withdrawal at the onset of exercise causes the increase in heart rate, central command did not decrease cardiac vagal efferent nerve activity but did allow cardiac sympathetic efferent nerve activity to produce cardiac acceleration. In addition, central command-evoked inhibition of the aortic baroreceptor-heart rate reflex blunted the baroreflex-mediated bradycardia elicited by aortic nerve stimulation, further increasing the heart rate at the onset of exercise. Spontaneous motor activity and associated cardiovascular responses disappeared in animals decerebrated at the midcollicular level. These findings indicate that the brain region including the caudal diencephalon and extending to the rostral mesencephalon may play a role in generating central command. Bicuculline microinjected into the midbrain ventral tegmental area of decerebrate rats produced a long-lasting repetitive activation of renal sympathetic nerve activity that was synchronized with the motor nerve discharge. When lidocaine was microinjected into the ventral tegmental area, the spontaneous motor activity and associated cardiovascular responses ceased. From these findings, we conclude that cerebral cortical outputs trigger activation of neural circuits within the caudal brain, including the ventral tegmental area, which causes central command to augment cardiac sympathetic outflow at the onset of exercise in decerebrate animal models. PMID:21984731

  11. Activation of BK and SK channels by efferent synapses on outer hair cells in high-frequency regions of the rodent cochlea.

    PubMed

    Rohmann, Kevin N; Wersinger, Eric; Braude, Jeremy P; Pyott, Sonja J; Fuchs, Paul Albert

    2015-02-01

    Cholinergic neurons of the brainstem olivary complex project to and inhibit outer hair cells (OHCs), refining acoustic sensitivity of the mammalian cochlea. In all vertebrate hair cells studied to date, cholinergic inhibition results from the combined action of ionotropic acetylcholine receptors and associated calcium-activated potassium channels. Although inhibition was thought to involve exclusively small conductance (SK potassium channels), recent findings have shown that BK channels also contribute to inhibition in basal, high-frequency OHCs after the onset of hearing. Here we show that the waveform of randomly timed IPSCs (evoked by high extracellular potassium) in high-frequency OHCs is altered by blockade of either SK or BK channels, with BK channels supporting faster synaptic waveforms and SK channels supporting slower synaptic waveforms. Consistent with these findings, IPSCs recorded from high-frequency OHCs that express BK channels are briefer than IPSCs recorded from low-frequency (apical) OHCs that do not express BK channels and from immature high-frequency OHCs before the developmental onset of BK channel expression. Likewise, OHCs of BKα(-/-) mice lacking the pore-forming α-subunit of BK channels have longer IPSCs than do the OHCs of BKα(+/+) littermates. Furthermore, serial reconstruction of electron micrographs showed that postsynaptic cisterns of BKα(-/-) OHCs were smaller than those of BKα(+/+) OHCs, and immunofluorescent quantification showed that efferent presynaptic terminals of BKα(-/-) OHCs were smaller than those of BKα(+/+) OHCs. Together, these findings indicate that BK channels contribute to postsynaptic function, and influence the structural maturation of efferent-OHC synapses. PMID:25653344

  12. Excitatory cholinergic and purinergic signaling in bladder are equally susceptible to botulinum neurotoxin a consistent with co-release of transmitters from efferent fibers.

    PubMed

    Lawrence, Gary W; Aoki, K Roger; Dolly, J Oliver

    2010-09-01

    Mediators of neuromuscular transmission in rat bladder strips were dissected pharmacologically to examine their susceptibilities to inhibition by botulinum neurotoxins (BoNTs) and elucidate a basis for the clinical effectiveness of BoNT/A in alleviating smooth muscle spasms associated with overactive bladder. BoNT/A, BoNT/C1, or BoNT/E reduced peak and average force of muscle contractions induced by electric field stimulation (EFS) in dose-dependent manners by acting only on neurogenic, tetrodotoxin-sensitive responses. BoNTs that cleaved vesicle-associated membrane protein proved to be much less effective. Acetylcholine (ACh) and ATP were found to provide virtually all excitatory input, because EFS-evoked contractions were abolished by the muscarinic receptor antagonist, atropine, combined with either a desensitizing agonist of P2X(1) and P2X(3) or a nonselective ATP receptor antagonist. Both transmitters were released in the innervated muscle layer and, thus, persisted after removal of urothelium. Atropine or a desensitizer of the P2X(1) or P2X(3) receptors did not alter the rate at which muscle contractions were weakened by BoNT/A. Moreover, although cholinergic and purinergic signaling could be partially delineated by using high-frequency EFS (which intensified a transient, largely atropine-resistant spike in muscle contractions that was reduced after P2X receptor desensitization), they proved equally susceptible to BoNT/A. Thus, equi-potent blockade of ATP co-released with ACh from muscle efferents probably contributes to the effectiveness of BoNT/A in treating bladder overactivity, including nonresponders to anticholinergic drugs. Because purinergic receptors are known mediators of sensory afferent excitation, inhibition of efferent ATP release by BoNT/A could also help to ameliorate acute pain and urgency sensation reported by some recipients.

  13. Evidence that limbic neural plasticity in the right hemisphere mediates partial kindling induced lasting increases in anxiety-like behavior: effects of low frequency stimulation (quenching?) on long term potentiation of amygdala efferents and behavior following kindling.

    PubMed

    Adamec, R E

    1999-08-21

    Behavioral and physiological effects of partial kindling of the right ventral hippocampus by perforant path (PP) stimulation were investigated in the cat. Partial kindling produced lasting changes in affect (increased defensive response to rats) and predatory attack (decreased pawing and biting attack). Partial kindling also induced long term potentiation (LTP) of amygdala efferent transmission to ventromedial hypothalamus (VMH) and periaqueductal gray (PAG) in left and right hemispheres. LTP of field population spikes evoked in area CA3 by PP stimulation was also observed. LTP was detected using evoked potential methods. These findings parallel previous studies of left PP-CA3 partial kindling. Analysis of covariance removing effects of LTP from behavioral changes suggests that initiation of increased defensiveness at 2 days after completion of partial kindling depended on LTP of left and right amygdalo-VMH and right amygdalo-PAG transmission. From 6 days after kindling onward, increased defensiveness depended on LTP of right amygdalo-PAG transmission. Depotentiation of amygdala efferent LTP by bilateral low frequency amygdala stimulation (LFS) (900 pulses at 1 Hz, once daily for 7 days) selectively reduced LTP in right amygdala efferents. At the same time, defensive, but not predatory attack behavior, was returned to levels seen prior to partial kindling. Both depotentiation and reduction of defensiveness were transient. Defensiveness increased to post-kindling levels by 76 days after LFS. At the same time, LTP was restored in the right amygdalo-PAG pathway. In contrast LTP in the right amygdalo-VMH pathway remained depotentiated. Effects of LFS were not due to damage, as thresholds to evoke amygdala efferent response were unchanged. These findings suggest that lasting change in affect following partial hippocampal kindling depends on LTP of right amygdala efferent transmission to PAG. The findings parallel studies of non-convulsant pharmacological induction of

  14. The anatomy of the callosal and visual association pathways in high-functioning autism: a DTI tractography study

    PubMed Central

    Thomas, Cibu; Humphreys, Kate; Jung, Kwan-jin; Minshew, Nancy; Behrmann, Marlene

    2010-01-01

    There is increasing recognition that many of the core behavioral impairments that characterize autism potentially emerge from poor neural synchronization across nodes comprising dispersed cortical networks. A likely candidate for the source of this atypical functional connectivity in autism is an alteration in the structural integrity of intra- and inter-hemispheric white matter tracts that form large-scale cortical networks. To test this hypothesis, in a group of adults with high functioning autism (HFA) and matched control participants, we used diffusion tensor tractography to compare the structural integrity of three intra-hemispheric visual-association white matter tracts, the inferior longitudinal fasciculus (ILF), the inferior fronto-occipito fasciculus (IFOF) and the uncinate fasciculus (UF), with the integrity of three sub-portions of the major inter-hemispheric fiber tract, the corpus callosum. Compared with the control group, the HFA group evinced an increase in the volume of the intra-hemispheric fibers, particularly in the left hemisphere, and a reduction in the volume of the forceps minor and body of the corpus callosum. The reduction in the volume of the forceps minor also correlated with an increase in repetitive and stereotypical behavior as measured by the Autism Diagnostic Interview. These findings suggest that the abnormalities in the integrity of key inter-and intra-hemispheric white matter tracts may underlie the atypical information processing observed in these individuals. PMID:20832784

  15. Vascular connections between the receptacle and empty achenes in sunflower (Helianthus annuus L.).

    PubMed

    Alkio, Merianne; Grimm, Eckhard

    2003-01-01

    Empty achenes in sunflower, particularly in the centre of the capitulum, may be caused by poor vascularization. This hypothesis was tested by microscopic examination and translocation experiments. Phloem and xylem were identified by fluorescence of aniline-blue-stained callose and autofluorescence, respectively. Vascular strands that extended from the receptacle into empty achenes were regularly found in longitudinal sections. The phloem-mobile probe, carboxyfluorescein, was translocated from the receptacle to the pericarp and the testa of empty achenes. Similarly, (14)CO(2)-derived (14)C-photoassimilates moved into empty achenes. The observations suggest that empty achenes are both structurally and functionally connected with the vascular system of the receptacle. Hence, deficient vascular connections do not prevent seed filling in sunflower. PMID:12493862

  16. D-(/sup 3/H)aspartate retrograde labelling of callosal and association neurons of somatosensory areas I and II of cats

    SciTech Connect

    Barbaresi, P.; Fabri, M.; Conti, F.; Manzoni, T.

    1987-09-08

    Experiments were carried out on cats to ascertain whether corticocortical neurons of somatosensory areas I (SI) and II (SII) could be labelled by retrograde axonal transport of D-(/sup 3/H)aspartate (D-(/sup 3/H)Asp). This tritiated enantiomer of the amino acid aspartate is (1) taken up selectively by axon terminals of neurons releasing aspartate and/or glutamate as excitatory neurotransmitter, (2) retrogradely transported and accumulated in perikarya, (3) not metabolized, and (4) visualized by autoradiography. A solution of D-(/sup 3/H)Asp was injected in eight cats in the trunk and forelimb zones of SI (two cats) or in the forelimb zone of SII (six cats). In order to compare the labelling patterns obtained with D-(/sup 3/H)Asp with those resulting after injection of a nonselective neuronal tracer, horseradish peroxidase (HRP) was delivered mixed with the radioactive tracer in seven of the eight cats. Furthermore, six additional animals received HRP injections in SI (three cats; trunk and forelimb zones) or SII (three cats; forelimb zone). D-(/sup 3/H)Asp retrograde labelling of perikarya was absent from the ipsilateral thalamus of all cats injected with the radioactive tracer but a dense terminal plexus of anterogradely labelled corticothalamic fibers from SI and SII was observed, overlapping the distribution area of thalamocortical neurons retrogradely labelled with HRP from the same areas. D-(/sup 3/H)Asp-labelled neurones were present in ipsilateral SII (SII-SI association neurones) in cats injected in SI. In these animals a bundle of radioactive fibres was observed in the rostral portion of the corpus callosum entering the contralateral hemisphere. There, neurones retrogradely labelled with silver grains were present in SI (SI-SI callosal neurons).

  17. Inhibition and Ultraviolet-Induced Chemical Modification of UDP-Glucose:(1,3)-β-Glucan (Callose) Synthase by Chlorpromazine 1

    PubMed Central

    Harriman, Robert W.; Shao, Ai-Ping; Wasserman, Bruce P.

    1992-01-01

    UDP-glucose:(1,3)-β-glucan (callose) synthase (CS) from storage tissue of red beet (Beta vulgaris L.) was strongly inhibited by the phenothiazine drug chlorpromazine (CPZ). In the absence of ultraviolet irradiation, CPZ was a noncompetitive inhibitor with 50% inhibitory concentration values for plasma membrane and solubilized CS of 100 and 90 μm, respectively. Both the Ca2+- and Mg2+- stimulated components of CS activity were affected. CPZ inhibition was partially alleviated at saturating levels of Ca2+, but not Mg2+, suggesting that CPZ interferes with the Ca2+-binding site of CS. Binding experiments with [14C]CPZ, however, showed strong non-specific partitioning of CPZ into the plasma membrane, providing evidence that perturbation of the membrane environment is probably the predominant mode of inhibition. Ultraviolet irradiation at 254 nm markedly enhanced CPZ inhibition, with complete activity loss following exposure to 4 μm CPZ for 2 min. Inhibition followed a pseudo-first order mechanism with at least three CPZ binding sites per CS complex. Under these conditions, [3H]CPZ was covalently incorporated into plasma membrane preparations by a free radical mechanism; however, polypeptide labeling profiles showed labeling to be largely nonspecific, with many polypeptides labeled even at [3H]CPZ levels as low as 1 μm, and with boiled membranes. Although CPZ is one of the most potent known inhibitors of CS, its use as a photolabel will require a homogeneous CS complex or establishment of conditions that protect against the interaction of CPZ with specific binding sites located on various polypeptide components of the CS complex. PMID:16653219

  18. Comprehensive connectivity of the mouse main olfactory bulb: analysis and online digital atlas

    PubMed Central

    Hintiryan, Houri; Gou, Lin; Zingg, Brian; Yamashita, Seita; Lyden, Hannah M.; Song, Monica Y.; Grewal, Arleen K.; Zhang, Xinhai; Toga, Arthur W.; Dong, Hong-Wei

    2012-01-01

    We introduce the first open resource for mouse olfactory connectivity data produced as part of the Mouse Connectome Project (MCP) at UCLA. The MCP aims to assemble a whole-brain connectivity atlas for the C57Bl/6J mouse using a double coinjection tracing method. Each coinjection consists of one anterograde and one retrograde tracer, which affords the advantage of simultaneously identifying efferent and afferent pathways and directly identifying reciprocal connectivity of injection sites. The systematic application of double coinjections potentially reveals interaction stations between injections and allows for the study of connectivity at the network level. To facilitate use of the data, raw images are made publicly accessible through our online interactive visualization tool, the iConnectome, where users can view and annotate the high-resolution, multi-fluorescent connectivity data (www.MouseConnectome.org). Systematic double coinjections were made into different regions of the main olfactory bulb (MOB) and data from 18 MOB cases (~72 pathways; 36 efferent/36 afferent) currently are available to view in iConnectome within their corresponding atlas level and their own bright-field cytoarchitectural background. Additional MOB injections and injections of the accessory olfactory bulb (AOB), anterior olfactory nucleus (AON), and other olfactory cortical areas gradually will be made available. Analysis of connections from different regions of the MOB revealed a novel, topographically arranged MOB projection roadmap, demonstrated disparate MOB connectivity with anterior versus posterior piriform cortical area (PIR), and exposed some novel aspects of well-established cortical olfactory projections. PMID:22891053

  19. Making Connections

    ERIC Educational Resources Information Center

    Turner, Paul

    2015-01-01

    This article aims to illustrate a process of making connections, not between mathematics and other activities, but within mathematics itself--between diverse parts of the subject. Novel connections are still possible in previously explored mathematics when the material happens to be unfamiliar, as may be the case for a learner at any career stage.…

  20. Observations on the connectivity of the parvicellular reticular formation with respect to a vomiting center

    NASA Technical Reports Server (NTRS)

    Mehler, W. R.

    1983-01-01

    The intrinsic and extrinsic connections of the parvicellular reticular formation (PCRF) that have been demonstrated by fiber degeneration studies and studied by more recently introduced horseradish peroxidase retrograde cell labeling are reviewed in an attempt to delimit the connectivity of the region in the PCRF where electrical stimulation produced emesis. Evidence is presented that certain specific functional subdivisions in PCRF such as the salivatory nuclei and the cells which give rise to the vestibular efferent projections can be delimited. An attempt is made to differentiate the sources of brain stem afferent connections with the nucleus of the tractus solitarius, the vagal nucleus and the nucleus ambiguus complex. The literature bearing on the histochemistry of the brain stem is reviewed in a search for clues to possible unique histo- or immunochemical cytological subdivisions in the parvicellular reticular formation.

  1. Efferents from the lateral frontal cortex to spinomedullary target areas, trigeminal nuclei, and spinally projecting brainstem regions in the hedgehog tenrec.

    PubMed

    Künzle, H; Lotter, G

    1996-08-12

    This study was done in the Madagascan lesser hedgehog tenrec, an insectivore with a very poorly differentiated neocortex. The cortical region, known to give rise to spinal projections, was injected with tracer, and the cortical efferents to brainstem and spinal cord were analyzed. Bulbar reticular fields, in addition, were identified according to their cells of origin and the laterality of their spinal projections after injection of tracer. Only few cortical fibers could be traced from the bulbar pyramid into the ipsilateral spinal cord, particularly to the lateral funiculus. The projections to the dorsal column nuclei and the classical spinally projecting brainstem regions were also weak. Faint projections were demonstrated to the nucleus of the posterior commissure and the nucleus of Darkschewitsch. In comparison to other mammals, there was no evidence that the contralateral cortico-bulbo-spinal pathway was strengthened, substituting for the almost non-existent contralateral corticospinal projection. Unlike the sensorimotor apparatus controlling limb and body movements, the brainstem regions controlling the head and neck received prominent cortical projections. Direct corticotrigeminal projections and indirect pathways were well represented. The projections to the trigeminal nuclei and the lateral reticular fields were clearly bilateral; those to the superior colliculus were predominantly ipsilateral. The corticobulbar fibers left the pyramid along its entire extent; the principal trigeminal nucleus and the dorsolateral pontine tegmentum were supplied by additional fibers of the corticotegmental tract. The lateral frontal cortex also projected densely to the dorsolateral hypothalamus, the periaqueductal gray, and the adjacent mesencephalic tegmentum, components of the emotional motor system.

  2. The auditory cross-section (AXS) test battery: A new way to study afferent/efferent relations linking body periphery (ear, voice, heart) with brainstem and cortex

    NASA Astrophysics Data System (ADS)

    Lauter, Judith

    2002-05-01

    Several noninvasive methods are available for studying the neural bases of human sensory-motor function, but their cost is prohibitive for many researchers and clinicians. The auditory cross section (AXS) test battery utilizes relatively inexpensive methods, yet yields data that are at least equivalent, if not superior in some applications, to those generated by more expensive technologies. The acronym emphasizes access to axes-the battery makes it possible to assess dynamic physiological relations along all three body-brain axes: rostro-caudal (afferent/efferent), dorso-ventral, and right-left, on an individually-specific basis, extending from cortex to the periphery. For auditory studies, a three-level physiological ear-to-cortex profile is generated, utilizing (1) quantitative electroencephalography (qEEG); (2) the repeated evoked potentials version of the auditory brainstem response (REPs/ABR); and (3) otoacoustic emissions (OAEs). Battery procedures will be explained, and sample data presented illustrating correlated multilevel changes in ear, voice, heart, brainstem, and cortex in response to circadian rhythms, and challenges with substances such as antihistamines and Ritalin. Potential applications for the battery include studies of central auditory processing, reading problems, hyperactivity, neural bases of voice and speech motor control, neurocardiology, individually-specific responses to medications, and the physiological bases of tinnitus, hyperacusis, and related treatments.

  3. The Importance of Lateral Connections in the Parietal Cortex for Generating Motor Plans

    PubMed Central

    Asher, Derrik E.; Oros, Nicolas; Krichmar, Jeffrey L.

    2015-01-01

    Substantial evidence has highlighted the significant role of associative brain areas, such as the posterior parietal cortex (PPC) in transforming multimodal sensory information into motor plans. However, little is known about how different sensory information, which can have different delays or be absent, combines to produce a motor plan, such as executing a reaching movement. To address these issues, we constructed four biologically plausible network architectures to simulate PPC: 1) feedforward from sensory input to the PPC to a motor output area, 2) feedforward with the addition of an efference copy from the motor area, 3) feedforward with the addition of lateral or recurrent connectivity across PPC neurons, and 4) feedforward plus efference copy, and lateral connections. Using an evolutionary strategy, the connectivity of these network architectures was evolved to execute visually guided movements, where the target stimulus provided visual input for the entirety of each trial. The models were then tested on a memory guided motor task, where the visual target disappeared after a short duration. Sensory input to the neural networks had sensory delays consistent with results from monkey studies. We found that lateral connections within the PPC resulted in smoother movements and were necessary for accurate movements in the absence of visual input. The addition of lateral connections resulted in velocity profiles consistent with those observed in human and non-human primate visually guided studies of reaching, and allowed for smooth, rapid, and accurate movements under all conditions. In contrast, Feedforward or Feedback architectures were insufficient to overcome these challenges. Our results suggest that intrinsic lateral connections are critical for executing accurate, smooth motor plans. PMID:26252871

  4. Only Connect.

    ERIC Educational Resources Information Center

    LeMieux, Anne C.

    2000-01-01

    Describes how the author connects with today's adolescent readers by means of laughter and literature. Claims young adult literature can facilitate the growth of empathy and provide an impetus for adolescents to transcend the isolation modern culture engenders. (NH)

  5. Classical conditioning of the nictitating membrane response of the rabbit. III. Connections of cerebellar lobule HVI.

    PubMed

    Yeo, C H; Hardiman, M J; Glickstein, M

    1985-01-01

    We report the connections of cerebellar cortical lobule HVI in the rabbit. We have studied the anterograde and retrograde transport of wheatgerm-agglutinated horseradish peroxidase (WGA-HRP) following its injection into HVI to reveal efferent and afferent connections. All of the cases showed strong anterograde transport to the anterior interpositus nucleus (AIP) - indicating that this is the major efferent target of HVI. Retrogradely labelled cells were found in the inferior olivary, spinal trigeminal, lateral reticular, inferior vestibular and pontine nuclei. Within the olive, the medial part of the rostral dorsal accessory olive (DAO) and the adjacent medial part of the principal olive (PO) were consistently labelled in all cases. This area is known to receive somatosensory information from the face and neck. There was no projection to the hemispheral part of lobule VI from visual parts of the olive within the dorsal cap and medial parts of the medial accessory olive. Likely sources of visual and auditory information to HVI are the dorsolateral basilar pontine nuclei and nucleus reticularis tegmenti pontis, which were densely labelled in all cases. These anatomical findings are consistent with the suggestion that, during NMR conditioning, information related to the periorbital shock unconditional stimulus (US) may be provided by climbing fibres to HVI and light and white noise conditional stimulus (CS) information may be supplied by pontine mossy fibres. PMID:4043270

  6. Connections of Auditory and Visual Cortex in the Prairie Vole (Microtus ochrogaster): Evidence for Multisensory Processing in Primary Sensory Areas

    PubMed Central

    Campi, Katharine L.; Bales, Karen L.; Grunewald, Rebecca

    2010-01-01

    In prairie voles, primary sensory areas are dominated by neurons that respond to one sensory modality, but some neurons also respond to stimulation of other modalities. To reveal the anatomical substrate for these multimodal responses, we examined the connections of the primary auditory area + the anterior auditory field (A1 + AAF), the temporal anterior area (TA), and the primary visual area (V1). A1 + AAF had intrinsic connections and connections with TA, multimodal cortex (MM), V1, and primary somatosensory area (S1). TA had intrinsic connections and connections with A1 + AAF, MM, and V2. Callosal connections were observed in homotopic locations in auditory cortex for both fields. A1 + AAF and TA receive thalamic input primarily from divisions of the medial geniculate nucleus but also from the lateral geniculate nucleus (LGd), the lateral posterior nucleus, and the ventral posterior nucleus (VP). V1 had dense intrinsic connections and connections with V2, MM, auditory cortex, pyriform cortex (Pyr), and, in some cases, somatosensory cortex. V1 had interhemispheric connections with V1, V2, MM, S1, and Pyr and received thalamic input from LGd and VP. Our results indicate that multisensory integration occurs in primary sensory areas of the prairie vole cortex, and this may be related to behavioral specializations associated with its niche. PMID:19395525

  7. Connections of auditory and visual cortex in the prairie vole (Microtus ochrogaster): evidence for multisensory processing in primary sensory areas.

    PubMed

    Campi, Katharine L; Bales, Karen L; Grunewald, Rebecca; Krubitzer, Leah

    2010-01-01

    In prairie voles, primary sensory areas are dominated by neurons that respond to one sensory modality, but some neurons also respond to stimulation of other modalities. To reveal the anatomical substrate for these multimodal responses, we examined the connections of the primary auditory area + the anterior auditory field (A1 + AAF), the temporal anterior area (TA), and the primary visual area (V1). A1 + AAF had intrinsic connections and connections with TA, multimodal cortex (MM), V1, and primary somatosensory area (S1). TA had intrinsic connections and connections with A1 + AAF, MM, and V2. Callosal connections were observed in homotopic locations in auditory cortex for both fields. A1 + AAF and TA receive thalamic input primarily from divisions of the medial geniculate nucleus but also from the lateral geniculate nucleus (LGd), the lateral posterior nucleus, and the ventral posterior nucleus (VP). V1 had dense intrinsic connections and connections with V2, MM, auditory cortex, pyriform cortex (Pyr), and, in some cases, somatosensory cortex. V1 had interhemispheric connections with V1, V2, MM, S1, and Pyr and received thalamic input from LGd and VP. Our results indicate that multisensory integration occurs in primary sensory areas of the prairie vole cortex, and this may be related to behavioral specializations associated with its niche. PMID:19395525

  8. Device Connectivity

    PubMed Central

    Walsh, John; Roberts, Ruth; Morris, Richard

    2015-01-01

    Patients with diabetes have to take numerous factors/data into their therapeutic decisions in daily life. Connecting the devices they are using by feeding the data generated into a database/app is supposed to help patients to optimize their glycemic control. As this is not established in practice, the different roadblocks have to be discussed to open the road. That large telecommunication companies are now entering this market might be a big help in pushing this forward. Smartphones offer an ideal platform for connectivity solutions. PMID:25614015

  9. Expressional Changes of Water Transport-related Molecules in the Efferent Ductules and Initial Segment of Mouse Treated with Bisphenol A-Containing Drinking Water for Two Generations.

    PubMed

    Han, Su-Yong; Lee, Ki-Ho

    2013-09-01

    Bisphenol A (BPA) is an estrogenic endocrine disrupter. However, depending on a way of treatment, the harmful effects of BPA have not been confirmed. Also, trans-generational effects of BPA on male reproduction are still controversial. Because the reabsorption of testicular fluid in the efferent ductules (ED) and initial segment (IS) is important for sperm maturation, the present study was designed to determine trans-generational effect of BPA administrated orally on expression of water transport-related molecules in the mouse ED and IS. Ethanol-dissolved BPA was diluted in water to be 100 ng (low), 10 μg (medium), and 1 mg/Ml water (high). BPA-containing water was provided for two generations. Expression of ion transporters and water channels in the ED and IS were measured by relative real-time PCR analysis. In the ED, BPA treatment caused expressional increases of carbonic anhydrase II, cystic fibrosis transmembrane regulator, Na(+)/K(+) ATPase α1 subunit, and aquaporin (AQP) 1. No change of Na(+)/H(+) exchange (NHE) 3 expression was detected. BPA treatment at medium dose resulted in an increase of AQP9 expression. In the IS, the highest expressional levels of all molecules tested were observed in medium-dose BPA treatment. Generally, high-dose BPA treatment resulted in a decrease or no change of gene expression. Fluctuation of NHE3 gene expression by BPA treatment at different concentrations was detected. These findings suggest that trans-generational exposure to BPA, even at low dose, could affect gene expression of water-transport related molecules. However, such effects of BPA would be differentially occurred in the ED and IS.

  10. The mammalian efferent vestibular system plays a crucial role in the high-frequency response and short-term adaptation of the vestibuloocular reflex.

    PubMed

    Hübner, Patrick P; Khan, Serajul I; Migliaccio, Americo A

    2015-12-01

    Although anatomically well described, the functional role of the mammalian efferent vestibular system (EVS) remains unclear. Unlike in fish and reptiles, the mammalian EVS does not seem to play a role in modulation of primary afferent activity in anticipation of active head movements. However, it could play a role in modulating long-term mechanisms requiring plasticity such as vestibular adaptation. We measured the efficacy of vestibuloocular reflex (VOR) adaptation in α9-knockout mice. These mice carry a missense mutation of the gene encoding the α9 nicotinic acetylcholine receptor (nAChR) subunit. The α9 nAChR subunit is expressed in the vestibular and auditory periphery, and its loss of function could compromise peripheral input from the predominantly cholinergic EVS. We measured the VOR gain (eye velocity/head velocity) in 26 α9-knockout mice and 27 cba129 control mice. Mice were randomly assigned to one of three groups: gain-increase adaptation (1.5×), gain-decrease adaptation (0.5×), or no adaptation (baseline, 1×). After adaptation training (horizontal rotations at 0.5 Hz with peak velocity 20°/s), we measured the sinusoidal (0.2-10 Hz, 20-100°/s) and transient (1,500-6,000°/s(2)) VOR in complete darkness. α9-Knockout mice had significantly lower baseline gains compared with control mice. This difference increased with stimulus frequency (∼ 5% <1 Hz to ∼ 25% >1 Hz). Moreover, vestibular adaptation (difference in VOR gain of gain-increase and gain-decrease adaptation groups as % of gain increase) was significantly reduced in α9-knockout mice (17%) compared with control mice (53%), a reduction of ∼ 70%. Our results show that the loss of α9 nAChRs moderately affects the VOR but severely affects VOR adaptation, suggesting that the EVS plays a crucial role in vestibular plasticity. PMID:26424577

  11. Age-related decline in Kv3.1b expression in the mouse auditory brainstem correlates with functional deficits in the medial olivocochlear efferent system.

    PubMed

    Zettel, Martha L; Zhu, Xiaoxia; O'Neill, William E; Frisina, Robert D

    2007-06-01

    Kv3.1b channel protein is widely distributed in the mammalian auditory brainstem, but studies have focused mainly on regions critical for temporal processing, including the medial nucleus of the trapezoid body (MNTB) and anteroventral cochlear nucleus (AVCN). Because temporal processing declines with age, this study was undertaken to determine if the expression of Kv3.1b likewise declines, and if changes are specific to these nuclei. Immunocytochemistry using an anti-Kv3.1b antibody was performed, and the relative optical density of cells and neuropil was determined from CBA/CaJ mice of four age groups. Declines in expression in AVCN, MNTB, and lateral superior olive (35, 26, and 23%) were found, but changes were limited to neuropil. Interestingly, cellular optical density declines were found in superior paraolivary nucleus, ventral nucleus of the trapezoid body, and lateral nucleus of the trapezoid body (24, 29, and 26%), which comprise the medial olivocochlear (MOC) feedback system. All declines occurred by middle age (15 months old). No age-related changes were found in the remaining regions of cochlear nucleus or in the inferior colliculus. Contralateral suppression of distortion-product otoacoustic emission amplitudes of age-matched littermates also declined by middle age, suggesting a correlation between Kv3.1 expression and MOC function. In search of more direct evidence for such a correlation, Kv3.1b knockout mice were examined. Knockouts show poor MOC function as compared to +/+ and +/- genotypes. Thus, Kv3.1b expression declines in MOC neurons by middle age, and these changes appear to correlate with functional declines in efferent activity in both middle-aged CBA mice and Kv3.1b knockout mice.

  12. College Connection

    ERIC Educational Resources Information Center

    Hewitt, Kimberly Kappler; Scalzo, Mary Jo

    2012-01-01

    This article describes Oakwood City School District's College Connection Study, which is now in its eighth year. The purpose of the study is to help the educators in the district learn how to effectively prepare students for success in the colleges of their choice. Teachers, administrators, and other staff members travel to colleges to conduct…

  13. Connecting Node

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J.; Raboin, Jasen L.; Spexarth, Gary R.

    2009-01-01

    A paper describes the Octanode, a connecting node that facilitates the integration of multiple docking mechanisms, hatches, windows, and internal and external systems with the use of flat surfaces. The Octanode is a 26- faced Great Rhombicuboctahedron Archi medean solid with six octagonshaped panels, eight hexagon-shaped panels, and 12 square panels using three unique, simple, flat shapes to construct a spherical approximation. Each flat shape can be constructed with a variety of material and manufacturing techniques, such as honeycomb composite panels or a pocketed skinstringer configuration, using conventional means. The flat shapes can be connected together and sealed to create a pressurizable volume by the use of any conventional means including welding or fastening devices and sealant. The node can then be connected to other elements to allow transfer between those elements, or it could serve as an airlock. The Octanode can be manufactured on the ground and can be integrated with subsystems including hatches and ports. The node can then be transported to its intended location, whether on orbit or on surface. Any of the flat panels could be replaced by curved ones, turning the node into a copula. Windows may be placed on flat panes with optimal viewing angles that are not blocked by large connecting nodes. The advantage of using flat panels to represent a spherical approximation is that this allows for easier integration of subsystems and design features.

  14. Get Connected

    ERIC Educational Resources Information Center

    Horton, Jessica; Hagevik, Rita; Adkinson, Bennett; Parmly, Jilynn

    2013-01-01

    Technology can be both a blessing and a curse in the classroom. Although technology can provide greater access to information and increase student engagement, if screen time replaces time spent outside, then students stand to lose awareness and connectivity to the surrounding natural environment. This article describes how Google Earth can foster…

  15. Making Connections

    ERIC Educational Resources Information Center

    Quillen, Ian

    2014-01-01

    "We used to send out books that looked like this," says Barbara Dreyer, as she holds the 500-page volume from one of the first-ever courses offered online by Connections Academy. "You could look at this information online, but, frankly, a lot of people were doing this," she adds, thumbing through the book's pages. Dreyer,…

  16. The responsive amygdala: treatment-induced alterations in functional connectivity in pediatric complex regional pain syndrome.

    PubMed

    Simons, L E; Pielech, M; Erpelding, N; Linnman, C; Moulton, E; Sava, S; Lebel, A; Serrano, P; Sethna, N; Berde, C; Becerra, L; Borsook, D

    2014-09-01

    The amygdala is a key brain region with efferent and afferent neural connections that involve complex behaviors such as pain, reward, fear, and anxiety. This study evaluated resting state functional connectivity of the amygdala with cortical and subcortical regions in a group of chronic pain patients (pediatric complex regional pain syndrome) with age-sex matched control subjects before and after intensive physical-biobehavioral pain treatment. Our main findings include (1) enhanced functional connectivity from the amygdala to multiple cortical, subcortical, and cerebellar regions in patients compared with control subjects, with differences predominantly in the left amygdala in the pretreated condition (disease state); (2) dampened hyperconnectivity from the left amygdala to the motor cortex, parietal lobe, and cingulate cortex after intensive pain rehabilitation treatment within patients with nominal differences observed among healthy control subjects from time 1 to time 2 (treatment effects); (3) functional connectivity to several regions key to fear circuitry (prefrontal cortex, bilateral middle temporal lobe, bilateral cingulate, hippocampus) correlated with higher pain-related fear scores; and (4) decreases in pain-related fear associated with decreased connectivity between the amygdala and the motor and somatosensory cortex, cingulate, and frontal areas. Our data suggest that there are rapid changes in amygdala connectivity after an aggressive treatment program in children with chronic pain and intrinsic amygdala functional connectivity activity serving as a potential indicator of treatment response.

  17. Connections of the superior colliculus with the tegmentum and the cerebellum in the hedgehog tenrec.

    PubMed

    Künzle, H

    1997-06-01

    Different tracer substances were injected into the superior colliculus (CoS) in order to study its afferents and efferents with the meso-rhombencephalic tegmentum, the precerebellar nuclei and the cerebellum in the Madagascan hedgehog tenrec. The overall pattern of tectal connectivity in tenrec was similar to that in other mammals, as, e.g. the efferents to the contralateral paramedian reticular formation. Similarly the origin of the cerebello-tectal projection in mainly the lateral portions of the tenrec's cerebellar nuclear complex corresponded to the findings in species with little binocular overlap. In comparison to other mammals, however, the tenrec showed a consistent projection to the ipsilateral inferior olivary nucleus, in addition to the classical contralateral tecto-olivary projection. The tenrec's CoS also appeared to receive an unusually prominent monoaminergic input particularly from the substantia nigra, pars compacta. There was a reciprocal tecto-parabigeminal projection, a distinct nuclear aggregation of parabigeminal neurons, however, was difficult to identify. The dorsal lemniscal nucleus did not show perikaryal labeling in contrast to the paralemniscal region. Similar to the cat but unlike the rat there were a few neurons in the nucleus of the central acoustic tract. Unlike the cat, but similar to the rat there was a distinct, predominantly ipsilateral projection to the magnocellular reticular field known to project spinalward.

  18. Convergence and divergence are mostly reciprocated properties of the connections in the network of cortical areas.

    PubMed

    Négyessy, László; Nepusz, Tamás; Zalányi, László; Bazsó, Fülöp

    2008-10-22

    Cognition is based on the integrated functioning of hierarchically organized cortical processing streams in a manner yet to be clarified. Because integration fundamentally depends on convergence and the complementary notion of divergence of the neuronal connections, we analysed integration by measuring the degree of convergence/divergence through the connections in the network of cortical areas. By introducing a new index, we explored the complementary convergent and divergent nature of connectional reciprocity and delineated the backward and forward cortical sub-networks for the first time. Integrative properties of the areas defined by the degree of convergence/divergence through their afferents and efferents exhibited distinctive characteristics at different levels of the cortical hierarchy. Areas previously identified as hubs exhibit information bottleneck properties. Cortical networks largely deviate from random graphs where convergence and divergence are balanced at low reciprocity level. In the cortex, which is dominated by reciprocal connections, balance appears only by further increasing the number of reciprocal connections. The results point to the decisive role of the optimal number and placement of reciprocal connections in large-scale cortical integration. Our findings also facilitate understanding of the functional interactions between the cortical areas and the information flow or its equivalents in highly recurrent natural and artificial networks.

  19. Macaque accessory optic system: II. Connections with the pretectum

    SciTech Connect

    Baleydier, C.; Magnin, M.; Cooper, H.M. )

    1990-12-08

    Connections of the accessory optic system (AOS) with the pretectum are described in the macaque monkey. Injections of tritiated amino acids in the pretectum demonstrate a major contralateral projection to the dorsal (DTN), lateral (LTN), and medial (MTN) terminal nuclei of the AOS and a sparser projection to the ipsilateral LTN. Injections of retrograde tracers, Fast Blue (FB), or wheat germ agglutinin horseradish peroxidase (WGA-HRP) plus nonconjugated horseradish peroxidase (HRP) in the LTN show that the pretectal-LTN projection originates from two nuclei. The main source of pretectal efferents to the LTN is from the pretectal olivary nucleus (OPN) and is entirely contralateral. This projection, which appears unique to primates, originates from the large multipolar cells of the OPN. In addition to this projection, the nucleus of the optic tract (NOT) projects to the ipsilateral LTN, as in nonprimates. Injection of WGA-HRP in the pretectum shows a reciprocal predominantely ipsilateral projection from the LTN to the pretectum. Retinas were observed after injection of FB in the LTN. The retinal ganglion cells projecting to the AOS are mainly distributed near the fovea and in the nasal region of the contralateral eye, suggesting a nasotemporal pattern of decussation. The demonstration of a direct connection between LTN and OPN forces to a reconsideration of the functional role of the AOS. Previous descriptions of luminance responsive cells in the LTN support a possible participation of this nucleus in the control of the pupillary light reflex.

  20. 78 FR 55684 - ConnectED Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-11

    ... stakeholders from the education, technology, and government sectors to share ideas, discuss policies, and... convene stakeholders from the education, technology, and government sectors to share ideas, discuss... National Telecommunications and Information Administration ConnectED Workshop AGENCY:...

  1. Adaptive algorithms to map how brain trauma affects anatomical connectivity in children

    NASA Astrophysics Data System (ADS)

    Dennis, Emily L.; Prasad, Gautam; Babikian, Talin; Kernan, Claudia; Mink, Richard; Babbitt, Christopher; Johnson, Jeffrey; Giza, Christopher C.; Asarnow, Robert F.; Thompson, Paul M.

    2015-12-01

    Deficits in white matter (WM) integrity occur following traumatic brain injury (TBI), and often persist long after the visible scars have healed. Heterogeneity in injury types and locations can complicate analyses, making it harder to discover common biomarkers for tracking recovery. Here we apply a newly developed adaptive connectivity method, EPIC (evolving partitions to improve connectomics) to identify differences in structural connectivity that persist longitudinally. This data comes from a longitudinal study, in which we scanned participants (aged 8-19 years) with anatomical and diffusion MRI in both the post-acute and chronic phases (1-6 months and 13-19 months post-injury). To identify patterns of abnormal connectivity, we trained a model on data from 32 TBI patients in the post-acute phase and 45 well-matched healthy controls, reducing an initial 68x68 connectivity matrix to a 14x14 matrix. We then applied this reduced parcellation to the chronic data in participants who had returned for their chronic assessment (21 TBI and 26 healthy controls) and tested for group differences. We found significant differences in two connections, comprising callosal fibers and long anterior-posterior fibers, with the TBI group showing increased fiber density relative to controls. Longitudinal analysis revealed that these were connections that were decreasing over time in the healthy controls, as is a common developmental phenomenon, but they were increasing in the TBI group. While we cannot definitively tell why this may occur with our current data, this study provides targets for longitudinal tracking, and poses questions for future investigation.

  2. Undifferentiated Connective Tissue Disease

    MedlinePlus

    ... Home Conditions Undifferentiated Connective Tissue Disease (UCTD) Undifferentiated Connective Tissue Disease (UCTD) Make an Appointment Find a Doctor ... L. Goldstein, MD, MMSc (February 01, 2016) Undifferentiated connective tissue disease (UCTD) is a systemic autoimmune disease. This ...

  3. Connective Tissue Disorders

    MedlinePlus

    Connective tissue is the material inside your body that supports many of its parts. It is the "cellular ... their work. Cartilage and fat are examples of connective tissue. There are over 200 disorders that impact connective ...

  4. Cortical chemoarchitecture shapes macroscale effective functional connectivity patterns in macaque cerebral cortex.

    PubMed

    Turk, Elise; Scholtens, Lianne H; van den Heuvel, Martijn P

    2016-05-01

    The mammalian cortex is a complex system of-at the microscale level-interconnected neurons and-at the macroscale level-interconnected areas, forming the infrastructure for local and global neural processing and information integration. While the effects of regional chemoarchitecture on local cortical activity are well known, the effect of local neurotransmitter receptor organization on the emergence of large scale region-to-region functional interactions remains poorly understood. Here, we examined reports of effective functional connectivity-as measured by the action of strychnine administration acting on the chemical balance of cortical areas-in relation to underlying regional variation in microscale neurotransmitter receptor density levels in the macaque cortex. Linking cortical variation in microscale receptor density levels to collated information on macroscale functional connectivity of the macaque cortex, we show macroscale patterns of effective corticocortical functional interactions-and in particular, the strength of connectivity of efferent macroscale pathways-to be related to the ratio of excitatory and inhibitory neurotransmitter receptor densities of cortical areas. Our findings provide evidence for the microscale chemoarchitecture of cortical areas to have a direct stimulating influence on the emergence of macroscale functional connectivity patterns in the mammalian brain. Hum Brain Mapp 37:1856-1865, 2016. © 2016 Wiley Periodicals, Inc. PMID:26970255

  5. The hippocampal continuation (indusium griseum): its connectivity in the hedgehog tenrec and its status within the hippocampal formation of higher vertebrates.

    PubMed

    Künzle, H

    2004-06-01

    The indusium griseum and its precallosal extension are usually considered poorly differentiated portions of the hippocampus. The connections of this so-called 'hippocampal continuation' (HCt) have only been analyzed so far in rodents, which show one of the least-developed HCt among mammals. In this study we have investigated the relatively well differentiated HCt of the small Madagascan hedgehog tenrec (Afrotheria) using histochemical and axonal transport techniques. The tenrec's HCt shows associative and commissural connections. It receives laminar specific afferents from the entorhinal cortex (collaterals from neurons projecting to the dentate area), the anterior and posterior piriform cortices as well as the supramammillary region. A few fibers also originate in the olfactory bulb and the dentate hilus. Among these input areas only the dentate hilus receives a significant reciprocal projection from the HCt. Additional HCt efferents are directed to the subcallosal septum (presumed septohippocampal nucleus), the olfactory tubercle and the islands of Calleja. With the exception of the supramammillary afferents and possible efferents to the supraoptic nucleus we failed, however, to demonstrate distinct thalamic and hypothalamic connections. A comparison of the connections of the HCt with those of the hippocampal subdivisions reveal some similarity between the HCt and the dentate area, but the overall pattern of connectivity does not permit a correlation of the HCt with the dentate area, let alone the cornu ammonis and the subiculum. This view is supported by histochemical findings in the tenrec (immunoreactivity to calcium binding proteins) as well as the rat (data taken from the literature). The HCt is therefore considered a region in its own right within the hippocampal formation. It may be tentatively correlated with the medial cortex of reptiles, while the dentate area and the cornu ammonis may have evolved de novo in mammals.

  6. Weakly connected neural nets

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    1990-01-01

    A new neural network architecture is proposed based upon effects of non-Lipschitzian dynamics. The network is fully connected, but these connections are active only during vanishingly short time periods. The advantages of this architecture are discussed.

  7. Resting state functional MRI in Parkinson's disease: the impact of deep brain stimulation on 'effective' connectivity.

    PubMed

    Kahan, Joshua; Urner, Maren; Moran, Rosalyn; Flandin, Guillaume; Marreiros, Andre; Mancini, Laura; White, Mark; Thornton, John; Yousry, Tarek; Zrinzo, Ludvic; Hariz, Marwan; Limousin, Patricia; Friston, Karl; Foltynie, Tom

    2014-04-01

    Depleted of dopamine, the dynamics of the parkinsonian brain impact on both 'action' and 'resting' motor behaviour. Deep brain stimulation has become an established means of managing these symptoms, although its mechanisms of action remain unclear. Non-invasive characterizations of induced brain responses, and the effective connectivity underlying them, generally appeals to dynamic causal modelling of neuroimaging data. When the brain is at rest, however, this sort of characterization has been limited to correlations (functional connectivity). In this work, we model the 'effective' connectivity underlying low frequency blood oxygen level-dependent fluctuations in the resting Parkinsonian motor network-disclosing the distributed effects of deep brain stimulation on cortico-subcortical connections. Specifically, we show that subthalamic nucleus deep brain stimulation modulates all the major components of the motor cortico-striato-thalamo-cortical loop, including the cortico-striatal, thalamo-cortical, direct and indirect basal ganglia pathways, and the hyperdirect subthalamic nucleus projections. The strength of effective subthalamic nucleus afferents and efferents were reduced by stimulation, whereas cortico-striatal, thalamo-cortical and direct pathways were strengthened. Remarkably, regression analysis revealed that the hyperdirect, direct, and basal ganglia afferents to the subthalamic nucleus predicted clinical status and therapeutic response to deep brain stimulation; however, suppression of the sensitivity of the subthalamic nucleus to its hyperdirect afferents by deep brain stimulation may subvert the clinical efficacy of deep brain stimulation. Our findings highlight the distributed effects of stimulation on the resting motor network and provide a framework for analysing effective connectivity in resting state functional MRI with strong a priori hypotheses.

  8. Cortical brain connectivity evaluated by graph theory in dementia: a correlation study between functional and structural data.

    PubMed

    Vecchio, Fabrizio; Miraglia, Francesca; Curcio, Giuseppe; Altavilla, Riccardo; Scrascia, Federica; Giambattistelli, Federica; Quattrocchi, Carlo Cosimo; Bramanti, Placido; Vernieri, Fabrizio; Rossini, Paolo Maria

    2015-01-01

    A relatively new approach to brain function in neuroscience is the "functional connectivity", namely the synchrony in time of activity in anatomically-distinct but functionally-collaborating brain regions. On the other hand, diffusion tensor imaging (DTI) is a recently developed magnetic resonance imaging (MRI)-based technique with the capability to detect brain structural connection with fractional anisotropy (FA) identification. FA decrease has been observed in the corpus callosum of subjects with Alzheimer's disease (AD) and mild cognitive impairment (MCI, an AD prodromal stage). Corpus callosum splenium DTI abnormalities are thought to be associated with functional disconnections among cortical areas. This study aimed to investigate possible correlations between structural damage, measured by MRI-DTI, and functional abnormalities of brain integration, measured by characteristic path length detected in resting state EEG source activity (40 participants: 9 healthy controls, 10 MCI, 10 mild AD, 11 moderate AD). For each subject, undirected and weighted brain network was built to evaluate graph core measures. eLORETA lagged linear connectivity values were used as weight of the edges of the network. Results showed that callosal FA reduction is associated to a loss of brain interhemispheric functional connectivity characterized by increased delta and decreased alpha path length. These findings suggest that "global" (average network shortest path length representing an index of how efficient is the information transfer between two parts of the network) functional measure can reflect the reduction of fiber connecting the two hemispheres as revealed by DTI analysis and also anticipate in time this structural loss. PMID:25613102

  9. [Connective tissue dysplasia].

    PubMed

    Piantkovskiĭ, A S

    2012-01-01

    The article presents a diagnosis of dysplasia of connective tissue in athletes, where the most important are the methods of clinical assessment using diagnostic tests and rating scales manifestation of connective tissue dysplasia. Evaluation of patients with suspected connective tissue dysplasia should include inspection of an ophthalmologist, orthopedic trauma, cardiology. Should also be carried out by criteria diagnosis degree of connective tissue dysplasia by T. Y. Smolnova (2003) (Large and small diagnostic criteria), which include: increased skin extensibility, joint hypermobility (sprain, dislocation and subluxation, flat feet), muscle hypotonia, a hereditary predisposition to the disease, evaluation of signs joint hypermobility (Beighton criteria). If during routine medical examination revealed athletes with manifestations of connective tissue dysplasia, they are subject to a more in-depth examination and observation. Early diagnosis of connective tissue dysplasia allows not only to plan the training process, but also reduces the trauma of athletes.

  10. An update on the connections of the ventral mesencephalic dopaminergic complex.

    PubMed

    Yetnikoff, L; Lavezzi, H N; Reichard, R A; Zahm, D S

    2014-12-12

    This review covers the intrinsic organization and afferent and efferent connections of the midbrain dopaminergic complex, comprising the substantia nigra, ventral tegmental area and retrorubral field, which house, respectively, the A9, A10 and A8 groups of nigrostriatal, mesolimbic and mesocortical dopaminergic neurons. In addition, A10dc (dorsal, caudal) and A10rv (rostroventral) extensions into, respectively, the ventrolateral periaqueductal gray and supramammillary nucleus are discussed. Associated intrinsic and extrinsic connections of the midbrain dopaminergic complex that utilize gamma-aminobutyric acid (GABA), glutamate and neuropeptides and various co-expressed combinations of these compounds are considered in conjunction with the dopamine-containing systems. A framework is provided for understanding the organization of massive afferent systems descending and ascending to the midbrain dopaminergic complex from the telencephalon and brainstem, respectively. Within the context of this framework, the basal ganglia direct and indirect output pathways are treated in some detail. Findings from rodent brain are briefly compared with those from primates, including humans. Recent literature is emphasized, including traditional experimental neuroanatomical and modern gene transfer and optogenetic studies. An attempt was made to provide sufficient background and cite a representative sampling of earlier primary papers and reviews so that people new to the field may find this to be a relatively comprehensive treatment of the subject. PMID:24735820

  11. Asymptotically hyperbolic connections

    NASA Astrophysics Data System (ADS)

    Fine, Joel; Herfray, Yannick; Krasnov, Kirill; Scarinci, Carlos

    2016-09-01

    General relativity in four-dimensions can be equivalently described as a dynamical theory of {SO}(3)∼ {SU}(2)-connections rather than metrics. We introduce the notion of asymptotically hyperbolic connections, and work out an analogue of the Fefferman–Graham expansion in the language of connections. As in the metric setup, one can solve the arising ‘evolution’ equations order by order in the expansion in powers of the radial coordinate. The solution in the connection setting is arguably simpler, and very straightforward algebraic manipulations allow one to see how the unconstrained by Einstein equations ‘stress–energy tensor’ appears at third order in the expansion. Another interesting feature of the connection formulation is that the ‘counter terms’ required in the computation of the renormalised volume all combine into the Chern–Simons functional of the restriction of the connection to the boundary. As the Chern–Simons invariant is only defined modulo large gauge transformations, the requirement that the path integral over asymptotically hyperbolic connections is well-defined requires the cosmological constant to be quantised. Finally, in the connection setting one can deform the 4D Einstein condition in an interesting way, and we show that asymptotically hyperbolic connection expansion is universal and valid for any of the deformed theories.

  12. Asymptotically hyperbolic connections

    NASA Astrophysics Data System (ADS)

    Fine, Joel; Herfray, Yannick; Krasnov, Kirill; Scarinci, Carlos

    2016-09-01

    General relativity in four-dimensions can be equivalently described as a dynamical theory of {SO}(3)˜ {SU}(2)-connections rather than metrics. We introduce the notion of asymptotically hyperbolic connections, and work out an analogue of the Fefferman-Graham expansion in the language of connections. As in the metric setup, one can solve the arising ‘evolution’ equations order by order in the expansion in powers of the radial coordinate. The solution in the connection setting is arguably simpler, and very straightforward algebraic manipulations allow one to see how the unconstrained by Einstein equations ‘stress-energy tensor’ appears at third order in the expansion. Another interesting feature of the connection formulation is that the ‘counter terms’ required in the computation of the renormalised volume all combine into the Chern-Simons functional of the restriction of the connection to the boundary. As the Chern-Simons invariant is only defined modulo large gauge transformations, the requirement that the path integral over asymptotically hyperbolic connections is well-defined requires the cosmological constant to be quantised. Finally, in the connection setting one can deform the 4D Einstein condition in an interesting way, and we show that asymptotically hyperbolic connection expansion is universal and valid for any of the deformed theories.

  13. Stretch induced hyperexcitability of mice callosal pathway

    PubMed Central

    Fan, Anthony; Stebbings, Kevin A.; Llano, Daniel A.; Saif, Taher

    2015-01-01

    Memory and learning are thought to result from changes in synaptic strength. Previous studies on synaptic physiology in brain slices have traditionally been focused on biochemical processes. Here, we demonstrate with experiments on mouse brain slices that central nervous system plasticity is also sensitive to mechanical stretch. This is important, given the host of clinical conditions involving changes in mechanical tension on the brain, and the normal role that mechanical tension plays in brain development. A novel platform is developed to investigate neural responses to mechanical stretching. Flavoprotein autofluoresence (FA) imaging was employed for measuring neural activity. We observed that synaptic excitability substantially increases after a small (2.5%) stretch was held for 10 min and released. The increase is accumulative, i.e., multiple stretch cycles further increase the excitability. We also developed analytical tools to quantify the spatial spread and response strength. Results show that the spatial spread is less stable in slices undergoing the stretch-unstretch cycle. FA amplitude and activation rate decrease as excitability increases in stretch cases but not in electrically enhanced cases. These results collectively demonstrate that a small stretch in physiological range can modulate neural activities significantly, suggesting that mechanical events can be employed as a novel tool for the modulation of neural plasticity. PMID:26300729

  14. Caldecott Connections to Science.

    ERIC Educational Resources Information Center

    Glandon, Shan

    This volume brings award-winning literature to all areas of the science curriculum. The lesson plan format includes the four stages of engagement, elaboration, exploration, and connection. Each story is followed by activities that make connections between literature, science, and the arts. Chapters include: (1) "Frog Went A-Courtin'," which…

  15. Charting Community Technology Connections.

    ERIC Educational Resources Information Center

    Wahl, Ellen; Hobson, Hartley; Jeffers, Laura

    Communities have a wealth of technology resources and history on which to draw in thinking about and using technology in ways that support their values and goals. The technology connections that exist in a community may not be obvious, however. The activities presented in this guide are designed to help identify some of those connections and…

  16. Real World Graph Connectivity

    ERIC Educational Resources Information Center

    Lind, Joy; Narayan, Darren

    2009-01-01

    We present the topic of graph connectivity along with a famous theorem of Menger in the real-world setting of the national computer network infrastructure of "National LambdaRail". We include a set of exercises where students reinforce their understanding of graph connectivity by analysing the "National LambdaRail" network. Finally, we give…

  17. Artificial limb connection

    NASA Technical Reports Server (NTRS)

    Owens, L. J.

    1974-01-01

    Connection simplifies and eases donning and removing artificial limb; eliminates harnesses and clamps; and reduces skin pressures by allowing bone to carry all tensile and part of compressive loads between prosthesis and stump. Because connection is modular, it is easily modified to suit individual needs.

  18. Tokens of Connection

    ERIC Educational Resources Information Center

    Crowley, Theresa

    2016-01-01

    When teachers make the effort to build a solid relationship with each student, built on trust, they often engender a life-long connection, one that's life-changing for the student. But how can teachers grow such long-lasting relationships with all students, especially disenfranchised learners and those who make it hard to connect? Crowley, a…

  19. Connecting Arithmetic to Algebra

    ERIC Educational Resources Information Center

    Darley, Joy W.; Leapard, Barbara B.

    2010-01-01

    Algebraic thinking is a top priority in mathematics classrooms today. Because elementary school teachers lay the groundwork to develop students' capacity to think algebraically, it is crucial for teachers to have a conceptual understanding of the connections between arithmetic and algebra and be confident in communicating these connections. Many…

  20. Reading and Writing Connections.

    ERIC Educational Resources Information Center

    Mason, Jana M., Ed.

    This collection of papers, from a conference on reading and writing connections held at the University of Illinois in October 1986, reflects the value of demonstrating connections between reading instruction and writing. The book shows practitioners how writing can be blended with reading instruction and how writing activities can be used not just…

  1. Connections: Writing about Family.

    ERIC Educational Resources Information Center

    Krebs, Jane P.

    1987-01-01

    Describes a teaching method in which high school sophomores (1) read A. Munro's "Connection," a short story connecting the author to her family origins; (2) interview relatives about their personal history; and (3) compose vignettes based on the notes collected during a three-week period. Provides numerous questions and prompts used to help the…

  2. An autoradiographic analysis of the cortical connections of the pallidal and cerebellar zones within the feline motor thalamus

    SciTech Connect

    Wensel, J.P.

    1989-01-01

    The feline motor thalamus relays both basal ganglia and cerebellar inputs to the motor cortex. This complex is classically subdivided into three nuclei: the ventroanterior nucleus (VA), the ventrolateral nucleus (VL), and the ventromedial nucleus (VM). Poor correlation between recognized patterns of cortical and subcortical connectivity and traditional boundaries used to distinguish these nuclei complicate the elucidation of the role they play in the elaboration of motor behavior. The recent demonstration of complementarity for the pallidothalamic and dentatothalamic projections to the motor thalamus of the cat provided the foundation for a revision of these nuclear borders to reflect differences in subcortical connectivity. Using a revised topography, this study analyzed the afferent and efferent connections of the feline VA and VL through the application of both anterograde and retrograde tracing techniques. The extent of the cerebellothalamic projection, as revealed by the bidirectional transport of WGA-HRP, was used to demarcate the boundary between VA and VL. Injections of tritiated amino acids into VA and VL allowed for the autoradiographic tracing of their cortical projections. Autoradiography was also used to demonstrate the distributions of corticothalamic projections from selected pericruciate and posterior parietal subfields to the motor thalamus.

  3. Covariant magnetic connection hypersurfaces

    NASA Astrophysics Data System (ADS)

    Pegoraro, F.

    2016-04-01

    > In the single fluid, non-relativistic, ideal magnetohydrodynamic (MHD) plasma description, magnetic field lines play a fundamental role by defining dynamically preserved `magnetic connections' between plasma elements. Here we show how the concept of magnetic connection needs to be generalized in the case of a relativistic MHD description where we require covariance under arbitrary Lorentz transformations. This is performed by defining 2-D magnetic connection hypersurfaces in the 4-D Minkowski space. This generalization accounts for the loss of simultaneity between spatially separated events in different frames and is expected to provide a powerful insight into the 4-D geometry of electromagnetic fields when .

  4. Nurturing Deep Connections.

    ERIC Educational Resources Information Center

    Kessler, Rachael

    2002-01-01

    Argues that the missing ingredient in school reform is soul, that is, deep connections among students, teachers, and administrators. Discusses five principles of leadership with soul: Personalize, pacing, permission, protection, and paradox. (PKP)

  5. Can we measure connectivity?

    NASA Astrophysics Data System (ADS)

    Brazier, Richard; Vericat, Damia; Cerda, Artemi; Brardinoni, Francesco; Batalla, Ramon; Masselink, Rens; Wittenberg, Lea; Nadal Romero, Estela; López-Tarazón, José; Estrany, Joan; Keesstra, Saskia

    2015-04-01

    Whilst the term 'connectivity' in hydrological and sediment-based research is becoming increasing well-known, it is neither used consistently in the existing literature, nor is it clear from that literature, that the connectivity of a landscape, or part of a landscape can be measured. However, it is argued that understanding how well critical source areas of water or sediment are connected to receiving surface waters, may be an essential step towards improvement of land management to mitigate flooding, soil erosion and water quality problems. The first part of this paper, therefore, explores what is currently meant by the term connectivity; addressing the differences between structural and functional, or process-based connectivity, specifically with reference to the movement of water and sediment through an ecosystem. We argue that most existing studies do not measure connectivity. Instead, they address only part of the story. Existing work may describe structural change in a landscape, which can perhaps elucidate the potential for connectivity to occur, or indeed the emergent spatial properties of an ecosystem, but it rarely quantifies the connectivity of an ecosystem in a process-based manner through time. Alternatively, a great deal of work describes fluxes of water and sediment at (sometimes multiple) points in a landscape and infers connectivity of the system via analysis of time series data; from rainfall peak to hydrograph peak or start of sediment flux until peak sediment flux within an event. Such data are doubtless useful to understand catchment function, but alone, they do not provide evidence that quantifies (for example) how well connected sediment sources are to the outlets of the catchments from which they flux. Finally, there are many examples of water and particularly sediment tracing studies, which attempt to link, either directly or indirectly water or sediment sources with their sinks (which might more usefully be termed temporary stores

  6. HIV-AIDS Connection

    MedlinePlus

    ... Marketing Share this: Main Content Area The HIV-AIDS Connection AIDS was first recognized in 1981 and ... is there overwhelming scientific consensus that HIV causes AIDS? Before HIV infection became widespread in the human ...

  7. Linac quadrupole connections

    SciTech Connect

    Stiening, R.

    1984-07-12

    Linac type QC and QCH quadrupoles are mounted on the accelerator with their power connection side facing the injector. The connections are on the top of the magnet. The correct polarity for magnets is shown. The magnetic centers of all magnets are measured. If the magnetic center is above the geometric center, the distance delta y is positive. If the magnetic center is to the right of the geometric center, the distance delta x is positive.

  8. [Connective tissue and inflammation].

    PubMed

    Jakab, Lajos

    2014-03-23

    The author summarizes the structure of the connective tissues, the increasing motion of the constituents, which determine the role in establishing the structure and function of that. The structure and function of the connective tissue are related to each other in the resting as well as inflammatory states. It is emphasized that cellular events in the connective tissue are part of the defence of the organism, the localisation of the damage and, if possible, the maintenance of restitutio ad integrum. The organism responds to damage with inflammation, the non specific immune response, as well as specific, adaptive immunity. These processes are located in the connective tissue. Sterile and pathogenic inflammation are relatively similar processes, but inevitable differences are present, too. Sialic acids and glycoproteins containing sialic acids have important roles, and the role of Siglecs is also highlighted. Also, similarities and differences in damages caused by pathogens and sterile agents are briefly summarized. In addition, the roles of adhesion molecules linked to each other, and the whole event of inflammatory processes are presented. When considering practical consequences it is stressed that the structure (building up) of the organism and the defending function of inflammation both have fundamental importance. Inflammation has a crucial role in maintaining the integrity and the unimpaired somato-psychological state of the organism. Thus, inflammation serves as a tool of organism identical with the natural immune response, inseparably connected with the specific, adaptive immune response. The main events of the inflammatory processes take place in the connective tissue.

  9. NASA CONNECT: Atmospheric Detectives

    NASA Technical Reports Server (NTRS)

    1999-01-01

    'The Measurement of All Things: Atmospheric Detectives' is the second of seven programs in the 1999-2000 NASA CONNECT series. Produced by NASA Langley Research Center's Office of Education, NASA CONNECT is an award-winning series of instructional programs designed to enhance the teaching of math, science and technology concepts in grades 5-8. NASA CONNECT establishes the 'connection' between the mathematics, science, and technology concepts taught in the classroom and NASA research. Each program in the series supports the national mathematics, science, and technology standards; includes a resource-rich teacher guide; and uses a classroom experiment and web-based activity to complement and enhance the math, science, and technology concepts presented in the program. NASA CONNECT is FREE and the programs in the series are in the public domain. Visit our web site and register. http://connect.larc.nasa.gov In 'The Measurement of All Things: Atmospheric Detectives' students will learn how scientists use satellites, lasers, optical detectors, and wavelengths of light to measure the presence of certain gaseous elements, compounds, and aerosols in the Earth's atmosphere.

  10. Quick connect fastener

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce (Inventor)

    1994-01-01

    A quick connect fastener and method of use is presented wherein the quick connect fastener is suitable for replacing available bolts and screws, the quick connect fastener being capable of installation by simply pushing a threaded portion of the connector into a member receptacle hole, the inventive apparatus being comprised of an externally threaded fastener having a threaded portion slidably mounted upon a stud or bolt shaft, wherein the externally threaded fastener portion is expandable by a preloaded spring member. The fastener, upon contact with the member receptacle hole, has the capacity of presenting cylindrical threads of a reduced diameter for insertion purposes and once inserted into the receiving threads of the receptacle member hole, are expandable for engagement of the receptacle hole threads forming a quick connect of the fastener and the member to be fastened, the quick connect fastener can be further secured by rotation after insertion, even to the point of locking engagement, the quick connect fastener being disengagable only by reverse rotation of the mated thread engagement.

  11. Algebraic connectivity and graph robustness.

    SciTech Connect

    Feddema, John Todd; Byrne, Raymond Harry; Abdallah, Chaouki T.

    2009-07-01

    Recent papers have used Fiedler's definition of algebraic connectivity to show that network robustness, as measured by node-connectivity and edge-connectivity, can be increased by increasing the algebraic connectivity of the network. By the definition of algebraic connectivity, the second smallest eigenvalue of the graph Laplacian is a lower bound on the node-connectivity. In this paper we show that for circular random lattice graphs and mesh graphs algebraic connectivity is a conservative lower bound, and that increases in algebraic connectivity actually correspond to a decrease in node-connectivity. This means that the networks are actually less robust with respect to node-connectivity as the algebraic connectivity increases. However, an increase in algebraic connectivity seems to correlate well with a decrease in the characteristic path length of these networks - which would result in quicker communication through the network. Applications of these results are then discussed for perimeter security.

  12. The carotid sinus connections: a WGA-HRP study in the cat.

    PubMed

    Torrealba, F; Claps, A

    1988-07-01

    The neural connections of the carotid sinus were studied by administration of horseradish peroxidase or a lectin conjugate to the adventitia of the carotid sinus of cats. The carotid sinus afferents project exclusively to the nucleus of the tractus solitarius (NTS). Rostral to the obex the projection is mainly ipsilateral with a strong contralateral component caudal to the obex. The carotid sinus projects to several NTS territories that do not receive afferents from the carotid body chemoreceptors; they are: the dorsolateral, the lateral extension of the commissural, the caudal intermediate, the ventrolateral and the gelatinosus subnuclei. In addition the carotid sinus central representation includes territories occupied also by carotid body terminals: dorsal, interstitial, rostral intermediate, medial and the medial part of commissural subnuclei (see previous paper). Labeled cell bodies were found in the petrosal (216 +/- 37, mean +/- S.E.M.) nodose (825 +/- 434) and superior cervical ganglia (3583 +/- 1227) demonstrating the sympathetic efferent innervation of the carotid sinus and a dual sensory innervation via both the glossopharyngeal and vagus nerves. PMID:2458165

  13. Neuropilin asymmetry mediates a left-right difference in habenular connectivity.

    PubMed

    Kuan, Yung-Shu; Yu, Hung-Hsiang; Moens, Cecilia B; Halpern, Marnie E

    2007-03-01

    The medial habenular nuclei of the zebrafish diencephalon, which lie bilateral to the pineal complex, exhibit left-right differences in their neuroanatomy, gene expression profiles and axonal projections to the unpaired midbrain target--the interpeduncular nucleus (IPN). Efferents from the left habenula terminate along the entire dorsoventral extent of the IPN, whereas axons from the right habenula project only to the ventral IPN. How this left-right difference in connectivity is established and the factors involved in differential target recognition are unknown. Prior to IPN innervation, we find that only the left habenula expresses the zebrafish homologue of Neuropilin1a (Nrp1a), a receptor for class III Semaphorins (Sema3s). Directional asymmetry of nrp1a expression relies on Nodal signaling and the presence of the left-sided parapineal organ. Loss of Nrp1a, through parapineal ablation or depletion by antisense morpholinos, prevents left habenular neurons from projecting to the dorsal IPN. Selective depletion of Sema3D, but not of other Sema family members, similarly disrupts innervation of the dorsal IPN. Conversely, Sema3D overexpression results in left habenular projections that extend to the dorsal IPN, as well as beyond the target. The results indicate that Sema3D acts in concert with Nrp1a to guide neurons on the left side of the brain to innervate the target nucleus differently than those on the right side. PMID:17251263

  14. Circumventricular organs and ANG II-induced salt appetite: blood pressure and connectivity.

    PubMed

    Fitts, D A; Starbuck, E M; Ruhf, A

    2000-12-01

    A lesion of the subfornical organ (SFO) may reduce sodium depletion-induced salt appetite, which is largely dependent on ANG II, and yet ANG II infusions directly into SFO do not provoke salt appetite. Two experiments were designed to address this apparent contradiction. In experiment 1 sustained infusions of ANG II into SFO did not produce a sustained elevation of blood pressure, and neither a reduction of blood pressure alone with minoxidil and captopril nor a reduction of both blood pressure and volume with furosemide and captopril enhanced salt appetite. Infusions of ANG II in the organum vasculosum laminae terminalis (OVLT) did evoke salt appetite without raising blood pressure. In experiment 2 knife cuts of the afferent and efferent fibers of the rostroventral pole of the SFO abolished water intake during an infusion of ANG II into the femoral vein but failed to reduce salt appetite during an infusion of ANG II into the OVLT. We conclude that 1) hypertension does not account for the failure of infusions of ANG II in the SFO to generate salt appetite and 2) the OVLT does not depend on its connectivity with the SFO to generate salt appetite during ANG II infusions. PMID:11080096

  15. The connections of the sensory organ of Bellonci with the brain in Isopoda (crustacea).

    PubMed

    Chaigneau, J; Chataigner, J P

    1977-07-26

    The peduncle linking the organ of Bellonci with the brain was examined in Sphaeroma serratum and Anilocra frontalis. This peduncle, in its extension to the brain, becomes a nerve-like tract with bundles of pedicles originating from the sensory cell bodies located in the organ of Bellonci. It ends at the level of the medulla interna in an alveolar region resulting from the swelling of the sensory pedicle terminations. At this level three types of connections have been observed. The first is characterized by afferent synapses to the brain with, in the sensory pedicle endings, structures similar to the presynaptic ribbons noted by some authors in photoreceptors of arthropods. The two other types include nerve fibres originating from the brain, one with small electron lucent vesicles, a second displaying larger vesicles with a core of medium density. These fibres form efferent synapses to the organ of Bellonci. The sensory differentiation of the organ of Bellonci in Isopoda is confirmed but its true role is not specified.

  16. Resting state functional MRI in Parkinson’s disease: the impact of deep brain stimulation on ‘effective’ connectivity

    PubMed Central

    Kahan, Joshua; Urner, Maren; Moran, Rosalyn; Flandin, Guillaume; Marreiros, Andre; Mancini, Laura; White, Mark; Thornton, John; Yousry, Tarek; Zrinzo, Ludvic; Hariz, Marwan; Limousin, Patricia; Friston, Karl

    2014-01-01

    Depleted of dopamine, the dynamics of the parkinsonian brain impact on both ‘action’ and ‘resting’ motor behaviour. Deep brain stimulation has become an established means of managing these symptoms, although its mechanisms of action remain unclear. Non-invasive characterizations of induced brain responses, and the effective connectivity underlying them, generally appeals to dynamic causal modelling of neuroimaging data. When the brain is at rest, however, this sort of characterization has been limited to correlations (functional connectivity). In this work, we model the ‘effective’ connectivity underlying low frequency blood oxygen level-dependent fluctuations in the resting Parkinsonian motor network—disclosing the distributed effects of deep brain stimulation on cortico-subcortical connections. Specifically, we show that subthalamic nucleus deep brain stimulation modulates all the major components of the motor cortico-striato-thalamo-cortical loop, including the cortico-striatal, thalamo-cortical, direct and indirect basal ganglia pathways, and the hyperdirect subthalamic nucleus projections. The strength of effective subthalamic nucleus afferents and efferents were reduced by stimulation, whereas cortico-striatal, thalamo-cortical and direct pathways were strengthened. Remarkably, regression analysis revealed that the hyperdirect, direct, and basal ganglia afferents to the subthalamic nucleus predicted clinical status and therapeutic response to deep brain stimulation; however, suppression of the sensitivity of the subthalamic nucleus to its hyperdirect afferents by deep brain stimulation may subvert the clinical efficacy of deep brain stimulation. Our findings highlight the distributed effects of stimulation on the resting motor network and provide a framework for analysing effective connectivity in resting state functional MRI with strong a priori hypotheses. PMID:24566670

  17. Inert electrode connection

    SciTech Connect

    Weyand, John D.; Woods, Robert W.; DeYoung, David H.; Ray, Siba P.

    1985-01-01

    An inert electrode connection is disclosed wherein a layer of inert electrode material is bonded to a layer of conductive material by providing at least one intermediate layer of material therebetween comprising a predetermined ratio of inert material to conductive material. In a preferred embodiment, the connection is formed by placing in a die a layer of powdered inert material, at least one layer of a mixture of powdered inert material and conductive material, and a layer of powdered conductive material. The connection is then formed by pressing the material at 15,000-20,000 psi to form a powder compact and then densifying the powder compact in an inert or reducing atmosphere at a temperature of 1200.degree.-1500.degree. C.

  18. Optimum connection management scheduling

    NASA Astrophysics Data System (ADS)

    Kadar, Ivan

    2000-08-01

    Connection Management plays a key role in both distributed 'local' network-centric and 'globally' connected info- centric systems. The role of Connection Management is to provide seamless demand-based sharing of the information products. For optimum distributed information fusion performance, these systems must minimize communications delays and maximize message throughput, and at the same time take into account relative-sensors-targets geometrical constraints and data pedigree. In order to achieve overall distributed 'network' effectiveness, these systems must be adaptive, and be able to distribute data s needed in real- time. A system concept will be described which provides optimum capacity-based information scheduling. A specific example, based on a satellite channel, is used to illustrate simulated performance results and their effects on fusion systems performance.

  19. Inert electrode connection

    DOEpatents

    Weyand, J.D.; Woods, R.W.; DeYoung, D.H.; Ray, S.P.

    1985-02-19

    An inert electrode connection is disclosed wherein a layer of inert electrode material is bonded to a layer of conductive material by providing at least one intermediate layer of material therebetween comprising a predetermined ratio of inert material to conductive material. In a preferred embodiment, the connection is formed by placing in a die a layer of powdered inert material, at least one layer of a mixture of powdered inert material and conductive material, and a layer of powdered conductive material. The connection is then formed by pressing the material at 15,000--20,000 psi to form a powder compact and then densifying the powder compact in an inert or reducing atmosphere at a temperature of 1,200--1,500 C. 5 figs.

  20. English and Film: Connecting Children to the World

    ERIC Educational Resources Information Center

    Reid, Mark

    2015-01-01

    This paper explores the processes behind drawing different kinds of inference from a single short film. It examines the range knowledge that groups of viewers are able to derive from listening to film sound, and from summarizing the work of a whole film, using the concepts of "aesthetic" and "efferent" reading set out by Louise…

  1. Connections across the Disciplines.

    ERIC Educational Resources Information Center

    Bicak, Charles J.; Bicak, Laddie J.

    1990-01-01

    Suggested is an approach to general biology which may be effective in sustaining student interest and infusing an appreciation for science. The goal of the approach is to foster life-long learning and capability to make connections and draw inferences. Examples using the levels of biotic organization are given. (CW)

  2. Long-Distance Connection

    ERIC Educational Resources Information Center

    Clift, Kate

    2010-01-01

    Transient populations, cultural diversity, language barriers, competing loyalties, and geographic separation are just some of the challenges international schools face in communicating and connecting with their alumni. And these issues are not going to get any easier as the sector grows. Communicating effectively with large, diverse groups of…

  3. High power connection system

    DOEpatents

    Schaefer, Christopher E.; Beer, Robert C.; McCall, Mark D.

    2000-01-01

    A high power connection system adapted for automotive environments which provides environmental and EMI shielding includes a female connector, a male connector, and a panel mount. The female connector includes a female connector base and a snap fitted female connector cover. The male connector includes a male connector base and a snap fitted male connector cover. The female connector base has at least one female power terminal cavity for seatably receiving a respective female power terminal. The male connector base has at least one male power terminal cavity for seatably receiving a respective male power terminal. The female connector is covered by a cover seal and a conductive shroud. A pair of lock arms protrude outward from the front end of the male connector base, pass through the panel mount and interface with a lever of a lever rotatably connected to the shroud to thereby mechanically assist mating of the male and female connectors. Safety terminals in the male and female connectors provide a last-to-connect-first-to-break connection with an HVIL circuit.

  4. Making the Connection

    ERIC Educational Resources Information Center

    Perna, Mark C.

    2006-01-01

    Enrollment marketing is not just about enrollment; it is about creating relationships and serving one's community or target audience for many years. In this article, the author states that the first step in building such relationships is making a connection, and that is what effective marketing is all about. Administrators, teachers and critical…

  5. A Connective Pedagogy.

    ERIC Educational Resources Information Center

    Goral, Mary

    2000-01-01

    Our increasingly hurried lifestyle, changes in family structure, and intense economic pressures place stress on children and families. Waldorf education provides an educational environment that alleviates this stress through a connective pedagogy that encompasses continuity of people, curriculum, and instruction; a reverence and respect for the…

  6. Smart Kids: SMART Connections.

    ERIC Educational Resources Information Center

    Martin, Jennifer; And Others

    1991-01-01

    SMART (Science, Math, and Relevant Technology) Connections, an afterschool offshoot of a program addressing the scarcity of women in science, provides low-income children and children of color, both boys and girls, with hands-on science experience. Efforts continue to be made to ensure that the program works equally for boys as for girls. (CJS)

  7. Our Cosmic Connection

    ERIC Educational Resources Information Center

    Young, Donna L.

    2005-01-01

    To help students understand the connection that Earth and the solar system have with the cosmic cycles of stellar evolution, and to give students an appreciation of the beauty and elegance of celestial phenomena, the Chandra X-Ray Center (CXC) educational website contains a stellar evolution module that is available free to teachers. In this…

  8. The CORALS Connection

    ERIC Educational Resources Information Center

    Plankis, Brian; Klein, Carolyn

    2010-01-01

    The Ocean, Reefs, Aquariums, Literacy, and Stewardship (CORALS) research program helps students connect global environmental issues to local concerns and personal choices. During the 18-week program, students strengthen their understanding of coral reef decline through a classroom aquarium activity, communicate with science experts, and create…

  9. CONNECT Special Demonstration Project.

    ERIC Educational Resources Information Center

    Hawk, Kim; And Others

    Project CONNECT (Inmate Advocacy) was developed to provide counseling to inmates involved in the education programs at Fayette County Prison in Uniontown, Pennsylvania, before and immediately following their release. Twenty-one inmates who had been selected through a screening process received individual basic skills remediation in a classroom…

  10. The Anansi Connection.

    ERIC Educational Resources Information Center

    Carger, Chris Liska

    1998-01-01

    Describes a teacher educator's efforts to connect children's literature, sponsored by a partnership between Northern Illinois University and Chicago Public Schools. In one project, student teachers used award-winning picture books to inspire African-American eighth graders to create pastels on black paper. In another, regional folk tales inspired…

  11. A School Connectivity Primer.

    ERIC Educational Resources Information Center

    O'Donovan, Eamonn

    2000-01-01

    Provides an overview of school networking options and explores what speedier broadband technologies mean for education. Topics include Ethernet; wireless options for connection to the Internet; local area networks; wide area networks; phone lines; satellite access; cable modems; digital subscriber line (DSL); and funding networks through the…

  12. Wedgethread pipe connection

    DOEpatents

    Watts, John D.

    2003-06-17

    Several embodiments of a wedgethread pipe connection are disclosed that have improved makeup, sealing, and non-loosening characteristics. In one embodiment, an open wedgethread is disclosed that has an included angle measured in the gap between the stab flank and the load flank to be not less than zero, so as to prevent premature wedging between mating flanks before the position of full makeup is reached, as does occur between trapped wedgethreads wherein the included angle is less than zero. The invention may be used for pipe threads large or small, as a flush joint, with collars, screwed into plates or it may even be used to reversibly connect such as solid posts to base members where a wide makeup torque range is desired. This Open wedgethread, as opposed to trapped wedgethreads, provides a threaded pipe connection that: is more cost-effective; can seal high pressure gas; can provide selectively a connection strength as high as the pipe strength; assures easy makeup to the desired position of full makeup within a wide torque range; may have a torque strength as high as the pipe torque strength; is easier to manufacture; is easier to gage; and is less subject to handling damage.

  13. Connections that Count

    ERIC Educational Resources Information Center

    Lloyd-Zannini, Lou

    2012-01-01

    What can parents and educators of gifted children do to help them build the connections that will allow them to thrive? In this article, the author suggests a few practical and simple things that parents and educators of gifted children might want to consider as they live and work with them day by day. He breaks those suggestions out into two…

  14. Technology and Internet Connections.

    ERIC Educational Resources Information Center

    Allen, Denise; Lindroth, Linda

    1996-01-01

    Suggests that teachers can use computer software and Internet connections to enhance curriculum and capitalize student's natural interest in sports and sports figures. Provides a list of activities that students can do in relation to the Olympic games and gives information on how technology can assist in such activities. Appropriate Internet…

  15. MedlinePlus Connect

    MedlinePlus

    ... Web application provide responses in different formats. The Web application returns a link to a formatted MedlinePlus Connect response page. This page will include links to information relevant to the problem/diagnosis, medication, or lab test. For a diagnosis/problem code, the response page ...

  16. Community Connection Curriculum.

    ERIC Educational Resources Information Center

    Center for Understanding the Built Environment, Prairie Village, KS.

    This curriculum packet contains two teacher-developed lesson plans, for use in the upper elementary grades, which focus on urban life. The first lesson plan, "Connecting Downtown" (Michael Gray), studies how engineering and design can make cities more efficient places. It provides a brief discussion on how people travel within large urban cores,…

  17. Making Connections through Conversation

    ERIC Educational Resources Information Center

    McGough, Julie; Nyberg, Lisa

    2013-01-01

    Children do not always see a connection between themselves and other living things. Sometimes they do not even realize that they, too, are animals and represent a link in the food chain. By obtaining, evaluating, and communicating information (Scientific and Engineering Practice #8 in "A Framework for K-12 Science Education" [NRC 2012,…

  18. Strengthening connections: functional connectivity and brain plasticity.

    PubMed

    Kelly, Clare; Castellanos, F Xavier

    2014-03-01

    The ascendancy of functional neuroimaging has facilitated the addition of network-based approaches to the neuropsychologist's toolbox for evaluating the sequelae of brain insult. In particular, intrinsic functional connectivity (iFC) mapping of resting state fMRI (R-fMRI) data constitutes an ideal approach to measuring macro-scale networks in the human brain. Beyond the value of iFC mapping for charting how the functional topography of the brain is altered by insult and injury, iFC analyses can provide insights into experience-dependent plasticity at the macro level of large-scale functional networks. Such insights are foundational to the design of training and remediation interventions that will best facilitate recovery of function. In this review, we consider what is currently known about the origin and function of iFC in the brain, and how this knowledge is informative in neuropsychological settings. We then summarize studies that have examined experience-driven plasticity of iFC in healthy control participants, and frame these findings in terms of a schema that may aid in the interpretation of results and the generation of hypotheses for rehabilitative studies. Finally, we outline some caveats to the R-fMRI approach, as well as some current developments that are likely to bolster the utility of the iFC paradigm for neuropsychology.

  19. Strengthening connections: functional connectivity and brain plasticity

    PubMed Central

    Kelly, Clare; Castellanos, F. Xavier

    2014-01-01

    The ascendancy of functional neuroimaging has facilitated the addition of network-based approaches to the neuropsychologist’s toolbox for evaluating the sequelae of brain insult. In particular, intrinsic functional connectivity (iFC) mapping of resting state fMRI (R-fMRI) data constitutes an ideal approach to measuring macro-scale networks in the human brain. Beyond the value of iFC mapping for charting how the functional topography of the brain is altered by insult and injury, iFC analyses can provide insights into effects of experience-dependent plasticity at the macro level of large-scale functional networks. Such insights are foundational to the design of training and remediation interventions that will best facilitate recovery of function. In this review, we consider what is currently known about the origin and function of iFC in the brain, and how this knowledge is informative in neuropsychological settings. We then summarize studies that have examined experience-driven plasticity of iFC in healthy control participants, and frame these findings in terms of a schema that may aid in the interpretation of results and the generation of hypothesis for rehabilitative studies. Finally, we outline some caveats to the R-fMRI approach, as well as some current developments that are likely to bolster the utility of the iFC paradigm for neuropsychology. PMID:24496903

  20. Cable shield connecting device

    DOEpatents

    Silva, Frank A.

    1979-01-01

    A cable shield connecting device for installation on a high voltage cable of the type having a metallic shield, the device including a relatively conformable, looped metal bar for placement around a bared portion of the metallic shield to extend circumferentially around a major portion of the circumference of the metallic shield while being spaced radially therefrom, a plurality of relatively flexible metallic fingers affixed to the bar, projecting from the bar in an axial direction and spaced circumferentially along the bar, each finger being attached to the metallic shield at a portion located remote from the bar to make electrical contact with the metallic shield, and a connecting conductor integral with the bar.

  1. Impaired consciousness is linked to changes in effective connectivity of the posterior cingulate cortex within the default mode network

    PubMed Central

    Crone, Julia Sophia; Schurz, Matthias; Höller, Yvonne; Bergmann, Jürgen; Monti, Martin; Schmid, Elisabeth; Trinka, Eugen; Kronbichler, Martin

    2015-01-01

    The intrinsic connectivity of the default mode network has been associated with the level of consciousness in patients with severe brain injury. Especially medial parietal regions are considered to be highly involved in impaired consciousness. To better understand what aspect of this intrinsic architecture is linked to consciousness, we applied spectral dynamic causal modeling to assess effective connectivity within the default mode network in patients with disorders of consciousness. We included 12 controls, 12 patients in minimally conscious state and 13 in vegetative state in this study. For each subject, we first defined the four key regions of the default mode network employing a subject-specific independent component analysis approach. The resulting regions were then included as nodes in a spectral dynamic causal modeling analysis in order to assess how the causal interactions across these regions as well as the characteristics of neuronal fluctuations change with the level of consciousness. The resulting pattern of interaction in controls identified the posterior cingulate cortex as the main driven hub with positive afferent but negative efferent connections. In patients, this pattern appears to be disrupted. Moreover, the vegetative state patients exhibit significantly reduced self-inhibition and increased oscillations in the posterior cingulate cortex compared to minimally conscious state and controls. Finally, the degree of self-inhibition and strength of oscillation in this region is correlated with the level of consciousness. These findings indicate that the equilibrium between excitatory connectivity towards posterior cingulate cortex and its feedback projections is a key aspect of the relationship between alterations in consciousness after severe brain injury and the intrinsic functional architecture of the default mode network. This impairment might be principally due to the disruption of the mechanisms underlying self-inhibition and neuronal

  2. Connective Tissue Ulcers

    PubMed Central

    Dabiri, Ganary; Falanga, Vincent

    2013-01-01

    Connective tissue disorders (CTD), which are often also termed collagen vascular diseases, include a number of related inflammatory conditions. Some of these diseases include rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis (scleroderma), localized scleroderma (morphea variants localized to the skin), Sjogren’s syndrome, dermatomyositis, polymyositis, and mixed connective tissue disease. In addition to the systemic manifestations of these diseases, there are a number of cutaneous features that make these conditions recognizable on physical exam. Lower extremity ulcers and digital ulcers are an infrequent but disabling complication of long-standing connective tissue disease. The exact frequency with which these ulcers occur is not known, and the cause of the ulcerations is often multifactorial. Moreover, a challenging component of CTD ulcerations is that there are still no established guidelines for their diagnosis and treatment. The morbidity associated with these ulcerations and their underlying conditions is very substantial. Indeed, these less common but intractable ulcers represent a major medical and economic problem for patients, physicians and nurses, and even well organized multidisciplinary wound healing centers. PMID:23756459

  3. Energy storage connection system

    DOEpatents

    Benedict, Eric L.; Borland, Nicholas P.; Dale, Magdelena; Freeman, Belvin; Kite, Kim A.; Petter, Jeffrey K.; Taylor, Brendan F.

    2012-07-03

    A power system for connecting a variable voltage power source, such as a power controller, with a plurality of energy storage devices, at least two of which have a different initial voltage than the output voltage of the variable voltage power source. The power system includes a controller that increases the output voltage of the variable voltage power source. When such output voltage is substantially equal to the initial voltage of a first one of the energy storage devices, the controller sends a signal that causes a switch to connect the variable voltage power source with the first one of the energy storage devices. The controller then causes the output voltage of the variable voltage power source to continue increasing. When the output voltage is substantially equal to the initial voltage of a second one of the energy storage devices, the controller sends a signal that causes a switch to connect the variable voltage power source with the second one of the energy storage devices.

  4. Afferent connections of the substantia innominata/basal nucleus of Meynert in carnivores and primates.

    PubMed

    Irle, E; Markowitsch, H J

    1986-01-01

    Afferent connections to the substantia innominata/nucleus basalis complex of monkeys and cats were traced by using the method of retrograde transport of horseradish peroxidase (HRP). Altogether ten injections of HRP were performed in four monkeys (Saimiri sciureus, Callithrix jacchus, Galago senegalensis) and in four cats, with either vertical or oblique needle approaches. The entire brains excluding the olfactory bulbs and the cerebellum were then screened for labeled neurons. In both monkey and cat brains, many retrogradely labeled neurons could be detected in the amygdala, hypothalamus, midline thalamus, zona incerta, and the fields of Forel. Further but weaker labeling occurred in the medial septal nucleus, diagonal band of Broca, olfactory tubercle, paraventricular, anterior, mediodorsal, and central lateral thalamic nuclei, lateral habenula, ventral tegmental area of Tsai, interpeduncular nucleus, parabrachial, raphe, dorsal tegmental nucleus and the locus caeruleus. Cortically, prefrontal, insular, entorhinal, prepiriform, and periamygdaloid areas of both species showed considerable labeling as well as the whole temporal lobe of the monkeys used. The perirhinal and basal temporal cortex of all cats showed moderate labeling. In both monkeys and cats, extremely scarce labeling occurred within the cingulate, retrosplenial, and subicular cortex. From an anatomical point of view, the manifold connections of the substantia innominata/basal nucleus of Meynert found in this study underscore the participation of these nuclear groups in motivational, emotional, and cognitive (e.g. mnemonic) functions. Considering the widespread cortical efferents of this complex, it is suggested that the substantia innominata/nucleus basalis of Meynert serves the transmission of information arising within the limbic system to the whole neocortex.

  5. Ventral tegmental (A10) system: neurobiology. 1. Anatomy and connectivity.

    PubMed

    Oades, R D; Halliday, G M

    1987-05-01

    The VTA contains the A10 group of DA containing neurons. These neurons have been grouped into nuclei to be found on the floor of the midbrain tegmentum--Npn, Nif, Npbp and Nln rostralis and caudalis. The VTA is traversed by many blood vessels and nerve fibers. Close to its poorly defined borders are found DA (A8, A9, A11) and 5-HT containing neurons (B8). Efferent projections of the VTA can be divided into 5 subsystems. The mesorhombencephalic projects to other monoaminergic nuclei, the cerebellum and a fine projection descends to other tegmental nuclei as far as the inferior olive. Fibers to the spinal cord have not been demonstrated. The mesodiencephalic path projects to several thalamic and hypothalamic nuclei and possibly the median eminence. Functionally important examples are the anterior hypothalamic-preoptic area, N. medialis dorsalis and reuniens thalami. These two subsystems are largely non-dopaminergic. A minor mesostriatal projection is overshadowed by the large mesolimbic projection to the accumbens, tuberculum olfactorium, septum lateralis and n. interstitialis stria terminalis. There are also mesolimbic connections with several amygdaloid nuclei (especially centralis and basolateralis), the olfactory nuclei and entorhinal cortex. A minor projection to the hippocampus has been detected. The mesocortical pathway projects to sensory (e.g. visual), motor, limbic (e.g. retrosplenial) and polysensory association cortices (e.g. prefrontal). Prefrontal, orbitofrontal (insular) and cingulate cortices receive the most marked innervation from the VTA. A more widespread presence of DA in other cortices of rodents becomes progressively more evident in carnivores and primates. Most but not all projections are unilateral. Some neurons project to more than one area in mesodiencephalic, limbic and cortical systems. The majority of these fibers ascend in the MFB. Most areas receiving a projection from the VTA (DA or non-DA) project back to the VTA. The

  6. Cross-hemispheric collaboration and segregation associated with task difficulty as revealed by structural and functional connectivity.

    PubMed

    Davis, Simon W; Cabeza, Roberto

    2015-05-27

    Although it is known that brain regions in one hemisphere may interact very closely with their corresponding contralateral regions (collaboration) or operate relatively independent of them (segregation), the specific brain regions (where) and conditions (how) associated with collaboration or segregation are largely unknown. We investigated these issues using a split field-matching task in which participants matched the meaning of words or the visual features of faces presented to the same (unilateral) or to different (bilateral) visual fields. Matching difficulty was manipulated by varying the semantic similarity of words or the visual similarity of faces. We assessed the white matter using the fractional anisotropy (FA) measure provided by diffusion tensor imaging (DTI) and cross-hemispheric communication in terms of fMRI-based connectivity between homotopic pairs of cortical regions. For both perceptual and semantic matching, bilateral trials became faster than unilateral trials as difficulty increased (bilateral processing advantage, BPA). The study yielded three novel findings. First, whereas FA in anterior corpus callosum (genu) correlated with word-matching BPA, FA in posterior corpus callosum (splenium-occipital) correlated with face-matching BPA. Second, as matching difficulty intensified, cross-hemispheric functional connectivity (CFC) increased in domain-general frontopolar cortex (for both word and face matching) but decreased in domain-specific ventral temporal lobe regions (temporal pole for word matching and fusiform gyrus for face matching). Last, a mediation analysis linking DTI and fMRI data showed that CFC mediated the effect of callosal FA on BPA. These findings clarify the mechanisms by which the hemispheres interact to perform complex cognitive tasks.

  7. Grid Connected Functionality

    DOE Data Explorer

    Baker, Kyri; Jin, Xin; Vaidynathan, Deepthi; Jones, Wesley; Christensen, Dane; Sparn, Bethany; Woods, Jason; Sorensen, Harry; Lunacek, Monte

    2016-08-04

    Dataset demonstrating the potential benefits that residential buildings can provide for frequency regulation services in the electric power grid. In a hardware-in-the-loop (HIL) implementation, simulated homes along with a physical laboratory home are coordinated via a grid aggregator, and it is shown that their aggregate response has the potential to follow the regulation signal on a timescale of seconds. Connected (communication-enabled), devices in the National Renewable Energy Laboratory's (NREL's) Energy Systems Integration Facility (ESIF) received demand response (DR) requests from a grid aggregator, and the devices responded accordingly to meet the signal while satisfying user comfort bounds and physical hardware limitations.

  8. Piston and connecting rod assembly

    NASA Technical Reports Server (NTRS)

    Brogdon, James William (Inventor); Gill, David Keith (Inventor); Chatten, John K. (Inventor)

    2001-01-01

    A piston and connecting rod assembly includes a piston crown, a piston skirt, a connecting rod, and a bearing insert. The piston skirt is a component separate from the piston crown and is connected to the piston crown to provide a piston body. The bearing insert is a component separate from the piston crown and the piston skirt and is fixedly disposed within the piston body. A bearing surface of a connecting rod contacts the bearing insert to thereby movably associate the connecting rod and the piston body.

  9. Control line sealing connection

    SciTech Connect

    Tohill, H.O.

    1984-07-10

    A sealing connection for the passage of a fluid control line through adjoining members is claimed. The connection comprises a metallic tubular sealing element provided with tapered end portions, each end having internal frusto-conical surfaces and external frusto-conical surfaces in coaxial alignment with the bore through the element. The external frusto-conical surfaceas provide metal-to-metal sealing with aligned frusto-conical seating surfaces in opposed pockets formed in aligned portions of the control line at their respective openings at the adjoining surfaces of the adjoined member. The tubular sealing element is subjected to axial compression between the frusto-conical pocket seating surfaces when the adjoined members are bolted tightly together which results in deformation of its tapered end portions to provide metal-to-metal sealing with the adjoined members which is effective to seal against both internal and external fluid pressurization of the control line and without internally obstructing or restricting the control line. Secondary sealing is provided by elastomeric O-ring seals mounted in circumferential annular grooves formed in the exterior of the tubular sealing element.

  10. Finding significantly connected voxels based on histograms of connection strengths

    NASA Astrophysics Data System (ADS)

    Kasenburg, Niklas; Pedersen, Morten Vester; Darkner, Sune

    2016-03-01

    We explore a new approach for structural connectivity based segmentations of subcortical brain regions. Connectivity based segmentations are usually based on fibre connections from a seed region to predefined target regions. We present a method for finding significantly connected voxels based on the distribution of connection strengths. Paths from seed voxels to all voxels in a target region are obtained from a shortest-path tractography. For each seed voxel we approximate the distribution with a histogram of path scores. We hypothesise that the majority of estimated connections are false-positives and that their connection strength is distributed differently from true-positive connections. Therefore, an empirical null-distribution is defined for each target region as the average normalized histogram over all voxels in the seed region. Single histograms are then tested against the corresponding null-distribution and significance is determined using the false discovery rate (FDR). Segmentations are based on significantly connected voxels and their FDR. In this work we focus on the thalamus and the target regions were chosen by dividing the cortex into a prefrontal/temporal zone, motor zone, somatosensory zone and a parieto-occipital zone. The obtained segmentations consistently show a sparse number of significantly connected voxels that are located near the surface of the anterior thalamus over a population of 38 subjects.

  11. Power converter connection configuration

    DOEpatents

    Beihoff, Bruce C.; Kehl, Dennis L.; Gettelfinger, Lee A.; Kaishian, Steven C.; Phillips, Mark G.; Radosevich, Lawrence D.

    2008-11-11

    EMI shielding is provided for power electronics circuits and the like via a direct-mount reference plane support and shielding structure. The thermal support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support forms a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

  12. NASA Connect: 'Plane Weather'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Excerpt from the NASA Connect show 'Plane Weather' This clip explains how our weather occurs, and why Solar radiation is responsible. Weather affects our daily lives. The elements of weather: rain, wind, fog, ice and snow affect the operation and flight of an airplane. In this program, NASA and FAA researchers will introduce students to math, science, and weather; demonstrate how these elements influence flight; and show how NASA and FAA research is used to limit the effects of these elements on flight. Students will examine: the tools, techniques, and technologies used by engineers and scientists to detect these and other climatological factors affecting aircraft in flight. The lesson and classroom experiment will involve students in the scientific process and emphasizing problem solving, measurement, and reasoning skills.

  13. NASA Connect: 'Plane Weather'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Excerpt from the NASA Connect show 'Plane Weather' This clip explains what high and low pressure weather systems are, and how they form. Weather affects our daily lives. The elements of weather: rain, wind, fog, ice and snow affect the operation and flight of an airplane. In this program, NASA and FAA researchers will introduce students to math, science, and weather; demonstrate how these elements influence flight; and show how NASA and FAA research is used to limit the effects of these elements on flight. Students will examine: the tools, techniques, and technologies used by engineers and scientists to detect these and other climatological factors affecting aircraft in flight. The lesson and classroom experiment will involve students in the scientific process and emphasizing problem solving, measurement, and reasoning skills.

  14. NASA Connect: 'Plane Weather'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Excerpt from the NASA Connect show 'Plane Weather' This clip explains what high and low pressure weather systems are, and how these affect weather patterns. Weather affects our daily lives. The elements of weather: rain, wind, fog, ice and snow affect the operation and flight of an airplane. In this program, NASA and FAA researchers will introduce students to math, science, and weather; demonstrate how these elements influence flight; and show how NASA and FAA research is used to limit the effects of these elements on flight. Students will examine: the tools, techniques, and technologies used by engineers and scientists to detect these and other climatological factors affecting aircraft in flight. The lesson and classroom experiment will involve students in the scientific process and emphasizing problem solving, measurement, and reasoning skills.

  15. Fuel injection valve connection

    SciTech Connect

    Eshleman, E.S.; Field, M.J.; Penwright, J.L.

    1987-09-15

    A fuel injection valve connection is described which consists of a fuel injection valve having a cylindrical inlet fitting. The fitting has a threaded internal surface and a cylindrical external surface. A fuel connector has a projection with a threaded external surface that mates with the threaded internal surface of the fitting. The connector also has a sleeve with a cylindrical internal surface surrounding the fitting and an O-ring sealingly engaging the internal surface of the sleeve and the external surface of the fitting, whereby the valve may be rotated relative to the connector without breaking the sealing engagement between the valve and the connector, and wherein the connector also has a tab engageable with the injector to prevent unthreading of the valve from the connector.

  16. Neurochemical phenotype of corticocortical connections in the macaque monkey: quantitative analysis of a subset of neurofilament protein-immunoreactive projection neurons in frontal, parietal, temporal, and cingulate cortices

    NASA Technical Reports Server (NTRS)

    Hof, P. R.; Nimchinsky, E. A.; Morrison, J. H.; Bloom, F. E. (Principal Investigator)

    1995-01-01

    The neurochemical characteristics of the neuronal subsets that furnish different types of corticocortical connections have been only partially determined. In recent years, several cytoskeletal proteins have emerged as reliable markers to distinguish subsets of pyramidal neurons in the cerebral cortex of primates. In particular, previous studies using an antibody to nonphosphorylated neurofilament protein (SMI-32) have revealed a consistent degree of regional and laminar specificity in the distribution of a subpopulation of pyramidal cells in the primate cerebral cortex. The density of neurofilament protein-immunoreactive neurons was shown to vary across corticocortical pathways in macaque monkeys. In the present study, we have used the antibody SMI-32 to examine further and to quantify the distribution of a subset of corticocortically projecting neurons in a series of long ipsilateral corticocortical pathways in comparison to short corticocortical, commissural, and limbic connections. The results demonstrate that the long association pathways interconnecting the frontal, parietal, and temporal neocortex have a high representation of neurofilament protein-enriched pyramidal neurons (45-90%), whereas short corticocortical, callosal, and limbic pathways are characterized by much lower numbers of such neurons (4-35%). These data suggest that different types of corticocortical connections have differential representation of highly specific neuronal subsets that share common neurochemical characteristics, thereby determining regional and laminar cortical patterns of morphological and molecular heterogeneity. These differences in neuronal neurochemical phenotype among corticocortical circuits may have considerable influence on cortical processing and may be directly related to the type of integrative function subserved by each cortical pathway. Finally, it is worth noting that neurofilament protein-immunoreactive neurons are dramatically affected in the course of

  17. Mixed connective tissue disease.

    PubMed

    Gunnarsson, Ragnar; Hetlevik, Siri Opsahl; Lilleby, Vibke; Molberg, Øyvind

    2016-02-01

    The concept of mixed connective tissue disease (MCTD) as a separate connective tissue disease (CTD) has persisted for more than four decades. High titers of antibodies targeting the U1 small nuclear ribonucleoprotein particle (U1 snRNP) in peripheral blood are a sine qua non for the diagnosis of MCTD, in addition to distinct clinical features including Raynaud's phenomenon (RP), "puffy hands," arthritis, myositis, pleuritis, pericarditis, interstitial lung disease (ILD), and pulmonary hypertension (PH). Recently, population-based epidemiology data from Norway estimated the point prevalence of adult-onset MCTD to be 3.8 per 100,000 and the mean annual incidence to be 2.1 per million per year, supporting the notion that MCTD is the least common CTD. Little is known about the etiology of MCTD, but recent genetic studies have confirmed that MCTD is a strongly HLA (​human leukocyte antigen)-linked disease, as the HLA profiles of MCTD differ distinctly from the corresponding profiles of ethnically matched healthy controls and other CTDs. In the first section of this review, we provide an update on the clinical, immunological, and genetic features of MCTD and discuss the relationship between MCTD and the other CTDs. Then we proceed to discuss the recent advances in therapy and our current understanding of prognosis and prognostic factors, especially those that are associated with the more serious pulmonary and cardiovascular complications of the disease. In the final section, we discuss some of the key, unresolved questions related to anti-RNP-associated diseases and indicate how these questions may be approached in future studies. PMID:27421219

  18. Stimulus-driven changes in sensorimotor behavior and neuronal functional connectivity application to brain-machine interfaces and neurorehabilitation.

    PubMed

    Rebesco, James M; Miller, Lee E

    2011-01-01

    Normal brain function requires constant adaptation as an organism interacts with the environment and learns to associate important sensory stimuli with appropriate motor actions. Neurological disorders may disrupt these learned associations, potentially requiring new functional pathways to be formed to replace the lost function. As a consequence, neural plasticity is a critical aspect of both normal brain function as well as the response to neurological injury. A brain-machine interface (BMI) represents a unique adaptive challenge to the nervous system. Efferent BMIs have been developed, which harness signals recorded from a tiny proportion of the motor cortex (M1) to effect control of an external device. There is also interest in the development of an afferent BMI that would supply information directly to the brain (e.g., the somatosensory cortex-S1) via electrical stimulation. If a bidirectional BMI that combined these interfaces were to be successful, new functional pathways would be necessary between the artificial inputs and outputs. Indeed, stimulation of S1 that is contingent upon the consequences of motor command signals recorded from M1 might form the basis for artificial Hebbian associations not unlike those driving learning in the normal brain. In this chapter, we review recent developments in both efferent and afferent BMIs, as well as experimental attempts to understand and mimic the Hebbian processes that give rise to plastic changes within the cortex. We have used a rat model to develop the computational and experimental tools necessary to describe changes in the way small networks of sensorimotor neurons interact and process information. We show that by repetitively pairing the recorded spikes of one neuron with electrical stimulation of another or by repetitively pairing electrical stimulation of two neurons, we can strengthen the inferred functional connection between the pair of neurons. We have also used the dual-stimulation protocol to enhance

  19. Double connections in total anomalous pulmonary venous connection.

    PubMed

    Arciprete, P; McKay, R; Watson, G H; Hamilton, D I; Wilkinson, J L; Arnold, R M

    1986-07-01

    Three infants who underwent operation for total anomalous pulmonary venous connection had unobstructed drainage of all the pulmonary veins to both the coronary sinus and left vertical vein. In one patient the anatomy was demonstrated preoperatively and complete correction accomplished without difficulty, but in two patients the second connection was discovered only at postoperative reinvestigation. Arbitrary classification of total anomalous pulmonary venous connection into cardiac, supracardiac, infracardiac, and mixed types does not lend itself to description of such lesions and may obscure their clinical importance. For these less common variants of total anomalous pulmonary venous connection, a more detailed and precise definition of morphology facilitates accurate surgical repair.

  20. Connecting node and method for constructing a connecting node

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J. (Inventor); Raboin, Jasen L. (Inventor); Spexarth, Gary R. (Inventor)

    2011-01-01

    A connecting node comprises a polyhedral structure comprising a plurality of panels joined together at its side edges to form a spherical approximation, wherein at least one of the plurality of panels comprises a faceted surface being constructed with a passage for integrating with one of a plurality of elements comprising a docking port, a hatch, and a window that is attached to the connecting node. A method for manufacturing a connecting node comprises the steps of providing a plurality of panels, connecting the plurality of panels to form a spherical approximation, wherein each edge of each panel of the plurality is joined to another edge of another panel, and constructing at least one of the plurality of panels to include a passage for integrating at least one of a plurality of elements that may be attached to the connecting node.

  1. School Psychology Awareness: Making Connections

    ERIC Educational Resources Information Center

    Cohn, Andrea; Cowan, Katherine C.

    2011-01-01

    A day in the life of a student at school is filled with potential connections (relationships, linkages in learning, behavioral choices, etc.). Friendships with peers, relationships with teachers, acknowledgements from administrators, encouragement from coaches: These are all interpersonal connections that are essential not only to making school an…

  2. The Always-Connected Generation

    ERIC Educational Resources Information Center

    Bull, Glen

    2010-01-01

    The Pew Internet and American Life project characterizes the millennials--the first generation to come of age in the new millennium--as the first "always-connected" generation. Significant aspects of culture are changing as a result. A changing world where all students are connected all the time has substantial educational implications. Despite…

  3. Making Connections: Beyond the Surface.

    ERIC Educational Resources Information Center

    Brutlag, Dan; Maples, Carole

    1992-01-01

    An integrated curriculum geometry unit, "Beyond the Surface," is presented and built around four principles promoting students' mental connections. The principles include a significant problem context, assignment of concrete, active tasks, employing tools embodying the mathematical concept, and reflection on established connections through…

  4. [Muscles and connective tissue: histology].

    PubMed

    Delage, J-P

    2012-10-01

    Here, we give some comments about the DVD movies "Muscle Attitudes" from Endovivo productions, the movies up lighting some loss in the attention given to studies on the connective tissue, and especially them into muscles. The main characteristics of the different components in the intra-muscular connective tissue (perimysium, endomysium, epimysium) are shown here with special references to their ordered architecture and special references to their spatial distributions. This connective tissue is abundant into the muscles and is in continuity with the muscles in vicinity, with their tendons and their sheath, sticking the whole on skin. This connective tissue has also very abundant connections on the muscles fibres. It is then assumed that the connective tissue sticks every organs or cells of the locomotion system. Considering the elastic properties of the collagen fibres which are the most abundant component of connective tissue, it is possible to up light a panel of connective tissue associated functions such as the transmission of muscle contractions or the regulation of protein and energetic muscles metabolism.

  5. Uncommon Connections with Common Numerators

    ERIC Educational Resources Information Center

    Lesser, Lawrence M.; Guthrie, Joe A.

    2012-01-01

    Undergraduate students who are pre-service teachers need to make connections between the college mathematics they are learning and the pre-college mathematics they will be teaching. Spanning a broad range of undergraduate curricula, this article describes useful lesser-known connections, explorations, and original proofs involving fractions. In…

  6. Diverless flowline connection system

    SciTech Connect

    Cox, D.S.

    1996-12-31

    The tie-in of flowlines and umbilicals to subsea trees and manifolds in deep water has traditionally been an expensive exercise. It generally requires the simultaneous presence of lay vessel and drill ship, or divers using a combination of rigging and gantries on the subsea structure. In recent years the development of a viable remote pull-in technique has become an important requirement for oil companies who are continuing to develop deeper and more marginal fields. The use of Remote Operated Vehicles (ROV`s) can not only provide the required costs savings, but eliminates the risks to man. Sonsub set out to design and build a system that was modular, could use the ROV for all subsea operations, and would only require minimal permanent subsea hardware support. These objectives were met with the completed system known as the Diverless Flowline Connection System (DFCS). The DFCS is capable of performing the tie-in of flowlines and umbilicals up to 18 in. O.D. The system is a light modular package that is easily handled and operated with any Work Class ROV in deepwater environments. The system has been extensively tested under a wide variety of conditions and is ready to perform the tie-in of two 13.5 in. and 6 in. flowline in the South China Sea in early 1996. In addition Sonsub have recently been contracted to perform the tie-in of 6 single bore flowlines ranging in size between 2.5 in. and 10 in., 14 multibore flowlines (2.5 in. and 8 in.) and 4 umbilicals in the North Sea off the coast of Norway.

  7. Carl Sagan's Cosmic Connection

    NASA Astrophysics Data System (ADS)

    Sagan, Carl; Agel, Jerome

    2000-08-01

    Foreword Freeman Dyson; Personal reflections Ann Druyan; Preface; Part I. Cosmic Perspective: 1. A transitional animal; 2. The Unicorn of Cetus; 3. A message from earth; 4. A message to earth; 5. Experiments in utopias; 6. Chauvinism; 7. Space exploration as a human enterprise I. The scientific interest; 8. Space exploration as a human enterprise II. The public interest; 9. Space exploration as a human enterprise III. The historical interest; Part II. The Solar System: 10. On teaching the first grade; 11. 'The ancient and legendary Gods of old'; 12. The Venus detective story; 13. Venus is hell; 14. Science and 'intelligence'; 15. The moons of Barsoom; 16. The mountains of Mars I. Observations from earth; 17. The mountains of Mars II. Observations from space; 18. The canals of Mars; 19. The lost pictures of Mars; 20. The Ice Age and the cauldron; 21. Beginnings and ends of the Earth; 22. Terraforming the plants; 23. The exploration and utlization of the solar system; Part III. Beyond the Solar System: 24. Some of my best friends are dolphins; 25. 'Hello, central casting? Send me twenty extraterrestrials'; 26. The cosmic connection; 27. Extraterrestrial life: an idea whose time has come; 28. Has the Earth been visited?; 29. A search strategy for detecting extraterrestrial intelligence; 30. If we succeed 31. Cables, drums, and seashells; 32. The night freight to the stars; 33. Astroengineering; 34. Twenty questions: a classification of cosmic civilisations; 35. Galactic cultural exchanges; 36. A passage to elsewhere; 37. Starfolk I. A Fable; 38. Starfolk II. A future; 39. Starfolk III. The cosmic Cheshire cats; Epilog David Morrison; Index.

  8. Alterations in brain structure and functional connectivity in prescription opioid-dependent patients.

    PubMed

    Upadhyay, Jaymin; Maleki, Nasim; Potter, Jennifer; Elman, Igor; Rudrauf, David; Knudsen, Jaime; Wallin, Diana; Pendse, Gautam; McDonald, Leah; Griffin, Margaret; Anderson, Julie; Nutile, Lauren; Renshaw, Perry; Weiss, Roger; Becerra, Lino; Borsook, David

    2010-07-01

    A dramatic increase in the use and dependence of prescription opioids has occurred within the last 10 years. The consequences of long-term prescription opioid use and dependence on the brain are largely unknown, and any speculation is inferred from heroin and methadone studies. Thus, no data have directly demonstrated the effects of prescription opioid use on brain structure and function in humans. To pursue this issue, we used structural magnetic resonance imaging, diffusion tensor imaging and resting-state functional magnetic resonance imaging in a highly enriched group of prescription opioid-dependent patients [(n=10); from a larger study on prescription opioid dependent patients (n=133)] and matched healthy individuals (n=10) to characterize possible brain alterations that may be caused by long-term prescription opioid use. Criteria for patient selection included: (i) no dependence on alcohol or other drugs; (ii) no comorbid psychiatric or neurological disease; and (iii) no medical conditions, including pain. In comparison to control subjects, individuals with opioid dependence displayed bilateral volumetric loss in the amygdala. Prescription opioid-dependent subjects had significantly decreased anisotropy in axonal pathways specific to the amygdala (i.e. stria terminalis, ventral amygdalofugal pathway and uncinate fasciculus) as well as the internal and external capsules. In the patient group, significant decreases in functional connectivity were observed for seed regions that included the anterior insula, nucleus accumbens and amygdala subdivisions. Correlation analyses revealed that longer duration of prescription opioid exposure was associated with greater changes in functional connectivity. Finally, changes in amygdala functional connectivity were observed to have a significant dependence on amygdala volume and white matter anisotropy of efferent and afferent pathways of the amygdala. These findings suggest that prescription opioid dependence is associated

  9. Requirements for soldered electrical connections

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This publication is applicable to NASA programs involving solder connections for flight hardware, mission essential support equipment, and elements thereof. This publication sets forth hand and wave soldering requirements for reliable electrical connections. The prime consideration is the physical integrity of solder connections. Special requirements may exist which are not in conformance with the requirements of this publication. Design documentation contains the detail for these requirements, and they take precedence over conflicting portions of this publication when they are approved in writing by the procuring NASA installation.

  10. Cybersecurity for Connected Diabetes Devices.

    PubMed

    Klonoff, David C

    2015-09-01

    Diabetes devices are increasingly connected wirelessly to each other and to data-displaying reader devices. Threats to the accurate flow of information and commands may compromise the function of these devices and put their users at risk of health complications. Sound cybersecurity of connected diabetes devices is necessary to maintain confidentiality, integrity, and availability of the data and commands. Diabetes devices can be hacked by unauthorized agents and also by patients themselves to extract data that are not automatically provided by product software. Unauthorized access to connected diabetes devices has been simulated and could happen in reality. A cybersecurity standard designed specifically for connected diabetes devices will improve the safety of these products and increase confidence of users that the products will be secure.

  11. Cybersecurity for Connected Diabetes Devices.

    PubMed

    Klonoff, David C

    2015-09-01

    Diabetes devices are increasingly connected wirelessly to each other and to data-displaying reader devices. Threats to the accurate flow of information and commands may compromise the function of these devices and put their users at risk of health complications. Sound cybersecurity of connected diabetes devices is necessary to maintain confidentiality, integrity, and availability of the data and commands. Diabetes devices can be hacked by unauthorized agents and also by patients themselves to extract data that are not automatically provided by product software. Unauthorized access to connected diabetes devices has been simulated and could happen in reality. A cybersecurity standard designed specifically for connected diabetes devices will improve the safety of these products and increase confidence of users that the products will be secure. PMID:25883162

  12. Cybersecurity for Connected Diabetes Devices

    PubMed Central

    Klonoff, David C.

    2015-01-01

    Diabetes devices are increasingly connected wirelessly to each other and to data-displaying reader devices. Threats to the accurate flow of information and commands may compromise the function of these devices and put their users at risk of health complications. Sound cybersecurity of connected diabetes devices is necessary to maintain confidentiality, integrity, and availability of the data and commands. Diabetes devices can be hacked by unauthorized agents and also by patients themselves to extract data that are not automatically provided by product software. Unauthorized access to connected diabetes devices has been simulated and could happen in reality. A cybersecurity standard designed specifically for connected diabetes devices will improve the safety of these products and increase confidence of users that the products will be secure. PMID:25883162

  13. Retinal connectivity and primate vision

    PubMed Central

    Lee, Barry B.; Martin, Paul R.; Grünert, Ulrike

    2012-01-01

    The general principles of retinal organization are now well known. It may seem surprising that retinal organization in the primate, which has a complex visual behavioral repertoire, appears relatively simple. In this review, we primarily consider retinal structure and function in primate species. Photoreceptor distribution and connectivity are considered as are connectivity in the outer and inner retina. One key issue is the specificity of retinal connections; we suggest that the retina shows connectional specificity but this is seldom complete, and we consider here the functional consequences of imprecise wiring. Finally, we consider how retinal systems can be linked to psychophysical descriptions of different channels, chromatic and luminance, which are proposed to exist in the primate visual system. PMID:20826226

  14. Symmetries in Connection Preserving Deformations

    NASA Astrophysics Data System (ADS)

    Ormerod, Christopher M.

    2011-05-01

    We wish to show that the root lattice of Bäcklund transformations of the q-analogue of the third and fourth Painlevé equations, which is of type (A2+A1)(1), may be expressed as a quotient of the lattice of connection preserving deformations. Furthermore, we will show various directions in the lattice of connection preserving deformations present equivalent evolution equations under suitable transformations. These transformations correspond to the Dynkin diagram automorphisms.

  15. MedlinePlus Connect: Web Service

    MedlinePlus

    ... https://medlineplus.gov/connect/service.html MedlinePlus Connect: Web Service To use the sharing features on this ... if you implement MedlinePlus Connect by contacting us . Web Service Overview The parameters for the Web service ...

  16. Review on Cold-Formed Steel Connections

    PubMed Central

    Tan, Cher Siang; Mohammad, Shahrin; Md Tahir, Mahmood; Shek, Poi Ngian

    2014-01-01

    The concept of cold-formed light steel framing construction has been widespread after understanding its structural characteristics with massive research works over the years. Connection serves as one of the important elements for light steel framing in order to achieve its structural stability. Compared to hot-rolled steel sections, cold-formed steel connections perform dissimilarity due to the thin-walled behaviour. This paper aims to review current researches on cold-formed steel connections, particularly for screw connections, storage rack connections, welded connections, and bolted connections. The performance of these connections in the design of cold-formed steel structures is discussed. PMID:24688448

  17. Review on cold-formed steel connections.

    PubMed

    Lee, Yeong Huei; Tan, Cher Siang; Mohammad, Shahrin; Tahir, Mahmood Md; Shek, Poi Ngian

    2014-01-01

    The concept of cold-formed light steel framing construction has been widespread after understanding its structural characteristics with massive research works over the years. Connection serves as one of the important elements for light steel framing in order to achieve its structural stability. Compared to hot-rolled steel sections, cold-formed steel connections perform dissimilarity due to the thin-walled behaviour. This paper aims to review current researches on cold-formed steel connections, particularly for screw connections, storage rack connections, welded connections, and bolted connections. The performance of these connections in the design of cold-formed steel structures is discussed.

  18. Review on cold-formed steel connections.

    PubMed

    Lee, Yeong Huei; Tan, Cher Siang; Mohammad, Shahrin; Tahir, Mahmood Md; Shek, Poi Ngian

    2014-01-01

    The concept of cold-formed light steel framing construction has been widespread after understanding its structural characteristics with massive research works over the years. Connection serves as one of the important elements for light steel framing in order to achieve its structural stability. Compared to hot-rolled steel sections, cold-formed steel connections perform dissimilarity due to the thin-walled behaviour. This paper aims to review current researches on cold-formed steel connections, particularly for screw connections, storage rack connections, welded connections, and bolted connections. The performance of these connections in the design of cold-formed steel structures is discussed. PMID:24688448

  19. Tubuloglomerular and connecting tubuloglomerular feedback during inhibition of various Na transporters in the nephron.

    PubMed

    Wang, Hong; D'Ambrosio, Martin A; Ren, YiLin; Monu, Sumit R; Leung, Pablo; Kutskill, Kristopher; Garvin, Jeffrey L; Janic, Branislava; Peterson, Edward L; Carretero, Oscar A

    2015-05-01

    Afferent (Af-Art) and efferent arterioles resistance regulate glomerular capillary pressure. The nephron regulates Af-Art resistance via: 1) vasoconstrictor tubuloglomerular feedback (TGF), initiated in the macula densa via Na-K-2Cl cotransporters (NKCC2) and 2) vasodilator connecting tubuloglomerular feedback (CTGF), initiated in connecting tubules via epithelial Na channels (ENaC). Furosemide inhibits NKCC2 and TGF. Benzamil inhibits ENaC and CTGF. In vitro, CTGF dilates preconstricted Af-Arts. In vivo, benzamil decreases stop-flow pressure (PSF), suggesting that CTGF antagonizes TGF; however, even when TGF is blocked, CTGF does not increase PSF, suggesting there is another mechanism antagonizing CTGF. We hypothesize that in addition to NKCC2, activation of Na/H exchanger (NHE) antagonizes CTGF, and when both are blocked CTGF dilates Af-Arts and this effect is blocked by a CTGF inhibitor benzamil. Using micropuncture, we studied the effects of transport inhibitors on TGF responses by measuring PSF while increasing nephron perfusion from 0 to 40 nl/min. Control TGF response (-7.9 ± 0.2 mmHg) was blocked by furosemide (-0.4 ± 0.2 mmHg; P < 0.001). Benzamil restored TGF in the presence of furosemide (furosemide: -0.2 ± 0.1 vs. furosemide+benzamil: -4.3 ± 0.3 mmHg; P < 0.001). With furosemide and NHE inhibitor, dimethylamiloride (DMA), increase in tubular flow increased PSF (furosemide+DMA: 2.7 ± 0.5 mmHg, n = 6), and benzamil blocked this (furosemide+DMA+benzamil: -1.1 ± 0.2 mmHg; P < 0.01, n = 6). We conclude that NHE in the nephron decreases PSF (Af-Art constriction) when NKCC2 and ENaC are inhibited, suggesting that in the absence of NKCC2, NHE causes a TGF response and that CTGF dilates the Af-Art when TGF is blocked with NKCC2 and NHE inhibitors. PMID:25715987

  20. Connecting Sun City with Sun-Earth connections

    NASA Astrophysics Data System (ADS)

    Lopez, R.; Turner, N.; Mammei, J.; Dominguez, O.; Schulte, H.

    Connecting Sun-City with Sun Earth Connections is a space science and education effort at the University of Texas at El Paso, funded by NASA. The goal is to use space science as a motivational tool for science education both in high school and at the un- dergraduate level. Activities include workshops for area teachers, visits by high school students to the university, visits by university faculty to area school, undergraduate re- search in space sciecne-related activities, and undergraduate curriculum development using space science themes. In this paper we will present an overview of the program and lesson learned to date.

  1. Nucleus of the solitary tract in the C57BL/6J mouse: Subnuclear parcellation, chorda tympani nerve projections, and brainstem connections

    PubMed Central

    Ganchrow, Donald; Ganchrow, Judith R; Cicchini, Vanessa; Bartel, Dianna L; Kaufman, Daniel; Girard, David; Whitehead, Mark C

    2013-01-01

    The nucleus of the solitary tract (NST) processes gustatory and related somatosensory information rostrally and general viscerosensory information caudally. To compare its connections with those of other rodents, this study in the C57BL/6J mouse provides a subnuclear cytoarchitectonic parcellation (Nissl stain) of the NST into rostral, intermediate, and caudal divisions. Subnuclei are further characterized by NADPH staining and P2X2 immunoreactivity (IR). Cholera toxin subunit B (CTb) labeling revealed those NST subnuclei receiving chorda tympani nerve (CT) afferents, those connecting with the parabrachial nucleus (PBN) and reticular formation (RF), and those interconnecting NST subnuclei. CT terminals are densest in the rostral central (RC) and medial (M) subnuclei; less dense in the rostral lateral (RL) subnucleus; and sparse in the ventral (V), ventral lateral (VL), and central lateral (CL) subnuclei. CTb injection into the PBN retrogradely labels cells in the aforementioned subnuclei; RC and M providing the largest source of PBN projection neurons. Pontine efferent axons terminate mainly in V and rostral medial (RM) subnuclei. CTb injection into the medullary RF labels cells and axonal endings predominantly in V at rostral and intermediate NST levels. Small CTb injections within the NST label extensive projections from the rostral division to caudal subnuclei. Projections from the caudal division primarily interconnect subnuclei confined to the caudal division of the NST; they also connect with the area postrema. P2X2-IR identifies probable vagal nerve terminals in the central (Ce) subnucleus in the intermediate/caudal NST. Ce also shows intense NADPH staining and does not project to the PBN. J. Comp. Neurol. 522:1565–1596, 2014. PMID:24151133

  2. Continuously Connected With Mobile IP

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Cisco Systems developed Cisco Mobile Networks, making IP devices mobile. With this innovation, a Cisco router and its connected IP devices can roam across network boundaries and connection types. Because a mobile user is able to keep the same IP address while roaming, a live IP connection can be maintained without interruption. Glenn Research Center jointly tested the technology with Cisco, and is working to use it on low-earth-orbiting research craft. With Cisco's Mobile Networks functionality now available in Cisco IOS Software release 12.2(4)T, the commercial advantages and benefits are numerous. The technology can be applied to public safety, military/homeland security, emergency management services, railroad and shipping systems, and the automotive industry. It will allow ambulances, police, firemen, and the U.S. Coast Guard to stay connected to their networks while on the move. In the wireless battlefield, the technology will provide rapid infrastructure deployment for U.S. national defense. Airline, train, and cruise passengers utilizing Cisco Mobile Networks can fly all around the world with a continuous Internet connection. Cisco IOS(R) Software is a registered trademark of Cisco Systems.

  3. The solar-stellar connection

    NASA Astrophysics Data System (ADS)

    Giampapa, Mark S.

    2016-07-01

    A review of some principal results achieved in the area of stellar astrophysics with its origins in solar physics - the Solar-Stellar Connection - is presented from the perspective of an observational astronomer. The historical origins of the Solar-Stellar Connection are discussed followed by a review of key results from observations of stellar cycles analogous to the solar cycle in terms of parameters relevant to dynamo theory. A review of facets of angular momentum evolution and irradiance variations, each of which is determined by emergent, dynamo-generated magnetic fields, is given. Recent considerations of the impacts of stellar magnetic activity on the ambient radiative and energetic particle environment of the habitable zone of exoplanet systems are summarized. Some anticipated directions of the Solar-Stellar Connection in the new era of astronomy as defined by the advent of transformative facilities are presented.

  4. Parcellating connectivity in spatial maps.

    PubMed

    Baldassano, Christopher; Beck, Diane M; Fei-Fei, Li

    2015-01-01

    A common goal in biological sciences is to model a complex web of connections using a small number of interacting units. We present a general approach for dividing up elements in a spatial map based on their connectivity properties, allowing for the discovery of local regions underlying large-scale connectivity matrices. Our method is specifically designed to respect spatial layout and identify locally-connected clusters, corresponding to plausible coherent units such as strings of adjacent DNA base pairs, subregions of the brain, animal communities, or geographic ecosystems. Instead of using approximate greedy clustering, our nonparametric Bayesian model infers a precise parcellation using collapsed Gibbs sampling. We utilize an infinite clustering prior that intrinsically incorporates spatial constraints, allowing the model to search directly in the space of spatially-coherent parcellations. After showing results on synthetic datasets, we apply our method to both functional and structural connectivity data from the human brain. We find that our parcellation is substantially more effective than previous approaches at summarizing the brain's connectivity structure using a small number of clusters, produces better generalization to individual subject data, and reveals functional parcels related to known retinotopic maps in visual cortex. Additionally, we demonstrate the generality of our method by applying the same model to human migration data within the United States. This analysis reveals that migration behavior is generally influenced by state borders, but also identifies regional communities which cut across state lines. Our parcellation approach has a wide range of potential applications in understanding the spatial structure of complex biological networks.

  5. Preservice Teachers Map Compassion: Connecting Social Studies and Literacy through Nonfictional Animal Stories

    ERIC Educational Resources Information Center

    Rule, Audrey C.; Montgomery, Sarah E.; Vander Zanden, Sarah M.

    2014-01-01

    Nonfiction stories of animal compassion were used in this literacy-social studies integrated lesson to address both efferent and aesthetic stances in transmediation of text from picture books to maps. Preservice early childhood and elementary teachers chose places from the nine recent children's stories, symbolizing them on a map while…

  6. Diverless remote operated flowline connections

    SciTech Connect

    Johnson, R.; Slider, M.; Galle, G.

    1997-07-01

    The diverless remote horizontal connection for a major project in the South China Sea was performed using the ABB Vetco Gray GSR connector in conjunction with a pull-in tool. New, innovative methods were developed whereby the hubs provide axial and angular misalignment capabilities and an ROV can make and break the connection and replace the innovative magnetic sealing assembly. The significance of this achievement is assessed with a focus on the implemented design philosophies, the principles of operation, the overall system reliability, the operational cost reduction, and the full-scale testing results. Additional comments are made concerning the applicability of this technology in various other subsea applications.

  7. Critical Connections: Health and Academics

    ERIC Educational Resources Information Center

    Michael, Shannon L.; Merlo, Caitlin L.; Basch, Charles E.; Wentzel, Kathryn R.; Wechsler, Howell

    2015-01-01

    Background: While it is a national priority to support the health and education of students, these sectors must better align, integrate, and collaborate to achieve this priority. This article summarizes the literature on the connection between health and academic achievement using the Whole School, Whole Community, and Whole Child (WSCC) framework…

  8. Art and the Cosmic Connection

    ERIC Educational Resources Information Center

    Cobb, Whitney H.; Aiello, Monica Petty; Macdonald, Reeves; Asplund, Shari

    2014-01-01

    The interdisciplinary unit described in this article utilizes "Art and the Cosmic Connection," a free program conceived of by artists Monica and Tyler Aiello and developed by the artists, scientists, and educators through NASA's Discovery and New Frontiers Programs, to inspire learners to explore mysterious worlds in our solar…

  9. Exploring Culture through Children's Connections.

    ERIC Educational Resources Information Center

    Kaser, Sandy; Short, Kathy G.

    1998-01-01

    Shares one teacher's attempts to highlight diversity and children's cultures in authentic ways. Examines three children's connections to culture and their own cultural identities by looking at issues they explored across the school year (family, family and religion, and ethnicity). Situates the discussion of multiculturalism in the context of "kid…

  10. Caldecott Connections to Social Studies.

    ERIC Educational Resources Information Center

    Glandon, Shan

    The Caldecott Medal is awarded annually by the Association for Library Service to Children, a division of the American Library Association, to the U.S. artist of the most distinguished picture book for children. This activity book is based on the idea that connections with art teachers are a natural result of a focus on Caldecott Award literature,…

  11. Reduced Prefrontal Connectivity in Psychopathy

    PubMed Central

    Motzkin, Julian C.; Newman, Joseph P.; Kiehl, Kent A.; Koenigs, Michael

    2012-01-01

    Linking psychopathy to a specific brain abnormality could have significant clinical, legal, and scientific implications. Theories on the neurobiological basis of the disorder typically propose dysfunction in a circuit involving ventromedial prefrontal cortex (vmPFC). However, to date there is limited brain imaging data to directly test whether psychopathy may indeed be associated with any structural or functional abnormality within this brain area. In this study, we employ two complementary imaging techniques to assess the structural and functional connectivity of vmPFC in psychopathic and non-psychopathic criminals. Using diffusion tensor imaging, we show that psychopathy is associated with reduced structural integrity in the right uncinate fasciculus, the primary white matter connection between vmPFC and anterior temporal lobe. Using functional magnetic resonance imaging, we show that psychopathy is associated with reduced functional connectivity between vmPFC and amygdala as well as between vmPFC and medial parietal cortex. Together, these data converge to implicate diminished vmPFC connectivity as a characteristic neurobiological feature of psychopathy. PMID:22131397

  12. Connecting the Dots: Rediscovering Continuity

    ERIC Educational Resources Information Center

    Camenga, Kristin A.; Yates, Rebekah B. Johnson

    2014-01-01

    The topic of continuity is typically not introduced until calculus and then reexamined in real analysis. Recognizing the connections between secondary school mathematics and the advanced mathematics studied at the college level allows teachers to better identify mathematical concepts in student ideas, motivate students by piquing their curiosity,…

  13. Connecting Slope, Steepness, and Angles

    ERIC Educational Resources Information Center

    Nagle, Courtney R.; Moore-Russo, Deborah

    2013-01-01

    All teachers, especially high school teachers, face the challenge of ensuring that students have opportunities to relate and connect the various representations and notions of mathematics concepts developed over the course of the pre-K-12 mathematics curriculum. NCTM's (2000) Representation Standard emphasizes the importance of students being…

  14. The Imagery-Creativity Connection.

    ERIC Educational Resources Information Center

    Daniels-McGhee, Susan; Davis, Gary A.

    1994-01-01

    This paper reviews historical highlights of the imagery-creativity connection, including early and contemporary accounts, along with notable examples of imagery in the creative process. It also looks at cross-modal imagery (synesthesia), a model of image-based creativity and the creative process, and implications for strengthening creativity by…

  15. Teaching, Connecting & Empowering Today's Learners

    ERIC Educational Resources Information Center

    Jones, Virginia R.

    2013-01-01

    Since career and technical education (CTE) is based historically on promoting technical, hands-on, real-world applications in numerous vocations, CTE educators are uniquely poised to offer more use of instructional technology in their classrooms. Many CTE educators have remarkable connections with industry partnerships, internships and learning…

  16. Elementary Algebra Connections to Precalculus

    ERIC Educational Resources Information Center

    Lopez-Boada, Roberto; Daire, Sandra Arguelles

    2013-01-01

    This article examines the attitudes of some precalculus students to solve trigonometric and logarithmic equations and systems using the concepts of elementary algebra. With the goal of enticing the students to search for and use connections among mathematical topics, they are asked to solve equations or systems specifically designed to allow…

  17. Gigabit Wireless for Network Connectivity

    ERIC Educational Resources Information Center

    Schoedel, Eric

    2009-01-01

    Uninterrupted, high-bandwidth network connectivity is crucial for higher education. Colleges and universities increasingly adopt gigabit wireless solutions because of their fiber-equivalent performance, quick implementation, and significant return on investment. For just those reasons, Rush University Medical Center switched from free space optics…

  18. Connecting the Dots in DAS

    ERIC Educational Resources Information Center

    Ford, Tracy

    2012-01-01

    Many institutions implement a distributed antenna system (DAS) as part of a holistic approach to providing better wireless coverage and capacity on campus. A DAS provides wireless service within a particular area or structure via a network of separate antenna nodes that are connected to a common source through fiber or coaxial cable. Because DAS…

  19. Connecting Remote Clusters with ATM

    SciTech Connect

    Hu, T.C.; Wyckoff, P.S.

    1998-10-01

    Sandia's entry into utilizing clusters of networked workstations is called Computational Plant or CPlant for short. The design of CPlant uses Ethernet to boot the individual nodes, Myrinet to communicate within a node cluster, and ATM to connect between remote clusters. This SAND document covers the work done to enable the use of ATM on the CPlant nodes in the Fall of 1997.

  20. The Reading/Writing Connection.

    ERIC Educational Resources Information Center

    Anderson, Nancy Comfort

    1998-01-01

    Discusses ways to motivate children to become readers and writers, characteristics of good children's literature, using patterned books as models, and prewriting activities; provides an annotated bibliography of 26 patterned books to encourage the reading/writing connection. A subset of updated folk and fairy tales is included. (LRW)

  1. The PC Connection Part III.

    ERIC Educational Resources Information Center

    Chu, David L.; Zilora, Karen S.

    1986-01-01

    Presents a series of four applications of data acquisition, system control, and data analysis using personal computers. Covers topics of pilot plant information and control, automation of drug safety evaluation, analysis and characterization of petroleum resources, and high-speed analog-digital conversion connections. Part three of a series on…

  2. School Wellness Policy: Community Connections

    ERIC Educational Resources Information Center

    Lambdin, Dolly; Erwin, Heather

    2007-01-01

    How can physical educators make connections to the larger community? This article discusses how physical educators can better inform community physical-activity leaders and coaches about appropriate instructional practices and how they can inform students about activities available in the community. It also offers suggestions for how to invite the…

  3. The Histogram-Area Connection

    ERIC Educational Resources Information Center

    Gratzer, William; Carpenter, James E.

    2008-01-01

    This article demonstrates an alternative approach to the construction of histograms--one based on the notion of using area to represent relative density in intervals of unequal length. The resulting histograms illustrate the connection between the area of the rectangles associated with particular outcomes and the relative frequency (probability)…

  4. Catecholaminergic connectivity to the inner ear, central auditory and vocal motor circuitry in the plainfin midshipman fish, Porichthys notatus

    PubMed Central

    Forlano, Paul M.; Kim, Spencer D.; Krzyminska, Zuzanna M.; Sisneros, Joseph A.

    2014-01-01

    Although the neuroanatomical distribution of catecholaminergic (CA) neurons has been well documented across all vertebrate classes, few studies have examined CA connectivity to physiologically and anatomically identified neural circuitry that controls behavior. The goal of this study was to characterize CA distribution in the brain and inner ear of the plainfin midshipman fish (Porichthys notatus) with particular emphasis on their relationship with anatomically labeled circuitry that both produces and encodes social acoustic signals in this species. Neurobiotin labeling of the main auditory endorgan, the saccule, combined with tyrosine hydroxylase immunofluorescence (TH-ir) revealed a strong CA innervation of both the peripheral and central auditory system. Diencephalic TH-ir neurons in the periventricular posterior tuberculum, known to be dopaminergic, send ascending projections to the ventral telencephalon and prominent descending projections to vocal-acoustic integration sites, notably the hindbrain octavolateralis efferent nucleus, as well as onto the base of hair cells in the saccule via nerve VIII. Neurobiotin backfills of the vocal nerve in combination with TH-ir revealed CA terminals on all components of the vocal pattern generator which appears to largely originate from local TH-ir neurons but may include diencephalic projections as well. This study provides strong evidence for catecholamines as important neuromodulators of both auditory and vocal circuitry and acoustic-driven social behavior in midshipman fish. This first demonstration of TH-ir terminals in the main endorgan of hearing in a non-mammalian vertebrate suggests a conserved and important anatomical and functional role for dopamine in normal audition. PMID:24715479

  5. Connect.

    ERIC Educational Resources Information Center

    Gralla, Preston

    1988-01-01

    Discusses two weather computer programs that allow users to see current weather maps and readings across the United States by modem hookup. Describes the features of "Weather Brief" and "Accu-Weather Forecaster" and includes the approximate daily phone cost of each. (MVL)

  6. Connections

    ERIC Educational Resources Information Center

    Wei, Cindy

    2007-01-01

    The author remembers back to freshmen year when NCSSSMST was considered a jumbled acronym and a pain to utter. But now, two years down the line, and their conference debut in only a few months, she remembers the NCSSSMST motto, "foster, support, and advance the creative efforts of those specialized schools whose primary purpose is to attract…

  7. ConnectED: President Obama's Plan for Connecting All Schools to the Digital Age

    ERIC Educational Resources Information Center

    The White House, 2013

    2013-01-01

    Driven by new digital technologies, the future of learning is increasingly interactive, individualized, and full of real-world experiences and information. Unfortunately, the average school has about the same connectivity as the average American home, but serves 200 times as many users, and fewer than 20 percent of educators say their school's…

  8. A Choice Reaction Time Index of Callosal Anatomical Homotopy

    ERIC Educational Resources Information Center

    Desjardins, Sameul; Braun, Claude M. J.; Achim, Andre; Roberge, Carl

    2009-01-01

    Tachistoscopically presented bilateral stimulus pairs not parallel to the meridian produced significantly longer RTs on a task requiring discrimination of shapes (Go/no-Go) than pairs emplaced symmetrically on each side of the meridian in Desjardins and Braun [Desjardins, S., & Braun, C. M. J. (2006). Homotopy and heterotopy and the bilateral…

  9. Perinatal exposure to music protects spatial memory against callosal lesions.

    PubMed

    Amagdei, Anca; Balteş, Felicia Rodica; Avram, Julia; Miu, Andrei C

    2010-02-01

    Several studies have indicated that the exposure of rodents to music modulates brain development and neuroplasticity, by mechanisms that involve facilitated hippocampal neurogenesis, neurotrophin synthesis and glutamatergic signaling. This study focused on the potential protection that the perinatal exposure to music, between postnatal days 2 and 32, could offer against functional deficits induced by neonatal callosotomy in rats. The spontaneous alternation and marble-burying behaviors were longitudinally measured in callosotomized and control rats that had been exposed to music or not. The results indicated that the neonatal callosotomy-induced spontaneous alternation deficits that became apparent only after postnatal day 45, about the time when the rat corpus callosum reaches its maximal levels of myelination. The perinatal exposure to music efficiently protected the spontaneous alternation performance against the deficits induced by callosotomy. The present findings may offer important insights into music-induced neuroplasticity, relevant to brain development and neurorehabilitation.

  10. Language and Development in FG Syndrome with Callosal Agenesis.

    ERIC Educational Resources Information Center

    McCardle, Peggy; Wilson, Bruce

    1993-01-01

    The FG syndrome is characterized by unusual facies; sudden infant death; developmental delay; and abnormalities of the cardiac, gastrointestinal, and central nervous systems. Serial evaluations of one case with isolated agenesis of the corpus callosum found consistent patterns over time in specific language impairments in syntactic and…

  11. Connections for solid oxide fuel cells

    DOEpatents

    Collie, Jeffrey C.

    1999-01-01

    A connection for fuel cell assemblies is disclosed. The connection includes compliant members connected to individual fuel cells and a rigid member connected to the compliant members. Adjacent bundles or modules of fuel cells are connected together by mechanically joining their rigid members. The compliant/rigid connection permits construction of generator fuel cell stacks from basic modular groups of cells of any desired size. The connections can be made prior to installation of the fuel cells in a generator, thereby eliminating the need for in-situ completion of the connections. In addition to allowing pre-fabrication, the compliant/rigid connections also simplify removal and replacement of sections of a generator fuel cell stack.

  12. The business case for connectivity

    NASA Technical Reports Server (NTRS)

    Adams, Dennis; Hirschheim, Rudy

    1991-01-01

    Information systems that provide competitive advantages to organizations can be broadly classified into those that improve the effectiveness of a business function and those that improve the reach of information in the organization. The latter, organizational connectivity systems, can be categorized as intraorganizational and interorganizational systems. Intraorganization systems provide connectivity to function areas within the business, while interorganizational systems support the exchange of business data between independent business units. These system are not confined to a single entity but span organizational boundaries which can be national or international in scope. A series of case studies was undertaken in an effort to better understand the issues and problems associated with providing an increased flow of information within and outside of an organization. Ten issues emerged from this study. In summary, it is necessary for firms to first consider how effective their internal communications systems are before launching projects that tie the organization to external systems.

  13. Correlating thalamocortical connectivity and activity

    NASA Astrophysics Data System (ADS)

    da Fontoura Costa, Luciano; Sporns, Olaf

    2006-07-01

    The segregated regions of the mammalian cerebral cortex and thalamus form an extensive and complex network, whose structure and function are still only incompletely understood. The present letter describes an application of the concepts of complex networks and random walks that allows the identification of nonrandom, highly structured features of thalamocortical connections and their potential effects on dynamic interactions between cortical areas in the cat brain. Utilizing large-scale anatomical data sets of this thalamocortical system, we investigate uniform random walks in such a network by considering the steady state eigenvector of the respective stochastic matrix. It is shown that thalamocortical connections are organized in such a way as to guarantee strong correlation between the outdegree and occupancy rate (a stochastic measure potentially related to activation) of each cortical area. Possible organizational principles underlying this effect are identified and discussed.

  14. Evaluation of connected health technology.

    PubMed

    O'Neill, Sonja A; Nugent, Chris D; Donnelly, Mark P; McCullagh, Paul; McLaughlin, James

    2012-01-01

    With current advances in sensing technology, communication networks and software applications, the use of connected health technology within the home environment has become both more affordable and widespread. Nevertheless, the introduction of this new care paradigm has brought with it many challenges, with one of the most notable being assessing of the impact or otherwise of its usage. The assessment of efficiency, benefit and utility of such technology is recognised as still being in its infancy. Traditional evaluation protocols may fail to address the specific challenges associated with increased use of networks, databases and home deployments, in addition to the multitude of factors influencing successful adoption. This article aims to delineate the required steps of connected health technology evaluations and move towards a common framework that can be used to support future evaluations. A series of recommendations are presented based on previous experience in the domain.

  15. Organelle biogenesis and interorganellar connections

    PubMed Central

    Daniele, Tiziana; Schiaffino, Maria Vittoria

    2014-01-01

    Membrane contact sites (MCSs) allow the exchange of molecules and information between organelles, even when their membranes cannot fuse directly. In recent years, a number of functions have been attributed to these contacts, highlighting their critical role in cell homeostasis. Although inter-organellar connections typically involve the endoplasmic reticulum (ER), we recently reported the presence of a novel MCSs between melanosomes and mitochondria. Melanosome-mitochondrion contacts appear mediated by fibrillar bridges resembling the protein tethers linking mitochondria and the ER, both for their ultrastructural features and the involvement of Mitofusin 2. The frequency of these connections correlates spatially and timely with melanosome biogenesis, suggesting a functional link between the 2 processes and in general that organelle biogenesis in the secretory pathway requires interorganellar crosstalks at multiple steps. Here, we summarize the different functions attributed to MCSs, and discuss their possible relevance for the newly identified melanosome-mitochondrion liaison. PMID:25346798

  16. On neural connectivity estimation problems.

    PubMed

    Baccalá, Luiz A; Sameshima, Koichi

    2015-01-01

    After briefly recapping and reframing the problem of neural connectivity and its implications for today's brain mapping efforts, we argue that supplementing/replacing traditional conservative correlation based analysis methods requires active user understanding of the aims and limitations of the newly proposed multivariate analysis frameworks before the new methods can gain general acceptance and full profit can be made from the expanded descriptive opportunities they offer. PMID:26737512

  17. Discovery External Tank Connection Check

    NASA Technical Reports Server (NTRS)

    1999-01-01

    In the Vehicle Assembly Building, Ken Strite, NASA Quality Control, inspects the connection between Space Shuttle Discovery and the external tank that will be used to launch mission STS-103 in early December. This 10 day mission is designed to replace aging parts on the nine year old Hubble Space Telescope and to upgrade some of its functioning systems. During the flight, the astronaut crew will replace all six of the observatory's gyroscopes, a fine guidance sensor, its main computer, and other equipment.

  18. A LISP-Ada connection

    NASA Technical Reports Server (NTRS)

    Jaworski, Allan; Lavallee, David; Zoch, David

    1987-01-01

    The prototype demonstrates the feasibility of using Ada for expert systems and the implementation of an expert-friendly interface which supports knowledge entry. In the Ford LISP-Ada Connection (FLAC) system LISP and Ada are used in ways which complement their respective capabilities. Future investigation will concentrate on the enhancement of the expert knowledge entry/debugging interface and on the issues associated with multitasking and real-time expert systems implementation in Ada.

  19. Applications of the connection machine

    SciTech Connect

    Waltz, D.L.

    1987-01-01

    The Connection Machine development effort was initiated in the belief that parallel processing and artificial intelligence could together accelerate the rate of progress toward truly intelligent machines. This progress is the result of the ease with which the machine can be programmed and the dramatic increase in compute power that the machine can bring to bear. The authors have been able to run many trials of experiments in instances where previously, running just one would have been considered an achievement and no further experimentation would have been done. This has enabled exploring a great many more hypotheses and to work on much larger problems that had been possible on previous-generation artificial intelligence workstations. The ease of programming is in part the result of a decision to use existing serial machines (the Symbolics 3600 or Digital Equipment Corporation VAX), thus leaving unchanged the operating systems, editors, file systems, debuggers, network communications systems, and so on, so as to provide familiar programming environments. The Connection Machine is programmed in conservative extensions of Common Lisp and C. Users familiar with these languages and with front-end computer systems have been able to produce results on the Connection Machine on the first day that they use it.

  20. Hydrological connectivity of soil pipes

    NASA Astrophysics Data System (ADS)

    Holden, J.

    2003-04-01

    Natural soil pipes are common in many parts of the world and particularly in blanket peat uplands yet there are problems in finding and defining soil pipe networks which are often located deep within the peat. Pipeflow can contribute a large proportion of runoff to the river systems in these upland environments and may significantly influence catchment sediment and solute yield. Ground penetrating radar (GPR) technology has recently been developed for non-destructive identification and mapping of soil pipes in peat catchments. While GPR can identify subsurface cavities, it cannot alone determine hydrological connectivity between one cavity and another. This poster presents results from an experiment to test the ability of GPR to establish hydrological connectivity between pipes through use of a tracer solution. Tracers such as sodium chloride were injected at a constant rate into an open pipe cavity. The GPR was moved across the test area downslope. The resultant radargrams were analysed and significantly increased reflectance was observed from a selection of cavities downslope. It was thus possible to determine hydrological connectivity of soil pipes within a dense pipe network across a hillslope without ground disturbance. In addition, tracers were added to the peat surface upslope of known pipe networks. It was possible to then trace the movement of water across and through the hillslope by using GPR to establish the connectivity of a range of flowpaths. Often pipe networks were supplied with water from overland flow entering through cracks and openings where the soil pipe was near the peat surface. Downslope, pipeflow contributed not only directly to streamflow but also to overland flow and near-surface throughflow on the hillslope. The same water that was within a pipe network at four metres depth could become near-surface throughflow outside of the pipe network a few metres down slope. These data allow the first three-dimensional picture of subsurface

  1. Connecting Related Rates and Differential Equations

    ERIC Educational Resources Information Center

    Brandt, Keith

    2012-01-01

    This article points out a simple connection between related rates and differential equations. The connection can be used for in-class examples or homework exercises, and it is accessible to students who are familiar with separation of variables.

  2. DS-Connect: The Down Syndrome Registry

    MedlinePlus

    ... Connect® is a powerful resource where people with Down syndrome and their families can: • Connect with researchers and ... interest in participating in certain clinical studies on Down Syndrome, including studies of new medications and other treatments. • ...

  3. MedlinePlus Connect: Web Application

    MedlinePlus

    ... https://medlineplus.gov/connect/application.html MedlinePlus Connect: Web Application To use the sharing features on this ... please see our guidelines and instructions on linking. Web Application Overview The API for the Web application ...

  4. MedlinePlus Connect: Technical Information

    MedlinePlus

    ... Service Technical Information Page MedlinePlus Connect Implementation Options Web Application How does it work? Responds to requests ... examples of MedlinePlus Connect Web Application response pages. Web Service How does it work? Responds to requests ...

  5. MedlinePlus Connect: Email List

    MedlinePlus

    ... https://medlineplus.gov/connect/emaillist.html MedlinePlus Connect: Email List To use the sharing features on this ... developments and exchange ideas with your colleagues. This email list will be useful for health IT developers ...

  6. Multicultural Environmental Education--Making Connections.

    ERIC Educational Resources Information Center

    Gaughan, Sharon

    1996-01-01

    Discusses Raptors Connecting Cultures (RCC), a multicultural environmental education program for Latino students. The RCC Program attempted to make connections between local ecology in eastern Pennsylvania and the students' home countries using the concept of migration as a link. Encourages the inclusion of contributions and connections from…

  7. 47 CFR 54.506 - Internal connections.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SERVICE Universal Service Support for Schools and Libraries § 54.506 Internal connections. (a) A service... instructional building of a school or to a non-administrative building of a library. Internal connections do not include connections that extend beyond a single school campus or single library branch. There is...

  8. 46 CFR 64.33 - Pipe connection.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Pipe connection. 64.33 Section 64.33 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.33 Pipe connection. Each pipe connection that is not a...

  9. Connectivity Changes in Parkinson's Disease.

    PubMed

    Cerasa, Antonio; Novellino, Fabiana; Quattrone, Aldo

    2016-10-01

    Parkinson's disease (PD) is a chronic and progressive movement disorder of the central nervous system characterized by widespread alterations in several non-motor aspects such as mood, sleep, olfactory, and cognition in addition to motor dysfunctions. Advanced neuroimaging using functional connectivity reconstruction of the human brain has provided a vast knowledge on the pathophysiological mechanisms underlying this disorder, but this, however, does not cover the overall inter-/intra-individual variability of PD phenotypes. The present review is aimed at discussing to what extent the evidence provided by group-based neuroimaging analysis in this field of study (using seed-based, network-based, or graph theory approaches) may be generalized. In particular, we summarized the literature on the application of resting-state functional connectivity studies to explore different neural correlates of motor and non-motor symptoms of PD and the neural mechanisms involved in treatment effects: effects of levodopa or deep brain stimulation. The lesson learnt from one decade of studies provides consistent evidence on the role of the altered communication between the striato-frontal pathways as a marker of PD-related motor degeneration, whereas in the non-motor domain, several missing pieces of a complex puzzle are provided. However, the main target is to present a new era of intelligent neuroimaging applications, where automated multivariate analysis of functional connectivity data may be used for moving from group-level statistical results to personalized predictions in a clinical setting. Although in its relative infancy, the evidence gathered so far suggests a new era of clinical neuroimaging is starting. PMID:27568202

  10. Connecting cognition and consumer choice.

    PubMed

    Bartels, Daniel M; Johnson, Eric J

    2015-02-01

    We describe what can be gained from connecting cognition and consumer choice by discussing two contexts ripe for interaction between the two fields. The first-context effects on choice-has already been addressed by cognitive science yielding insights about cognitive process but there is promise for more interaction. The second is learning and representation in choice where relevant theories in cognitive science could be informed by consumer choice, and in return, could pose and answer new questions. We conclude by discussing how these two fields of research stand to benefit from more interaction, citing examples of how interfaces of cognitive science with other fields have been illuminating for theories of cognition.

  11. The heart-mind connection.

    PubMed

    Hill, Mary; Weber, Regina; Werner, Sandy

    2006-09-01

    A clear connection exists between mental health and heart disease, which requires assessment, collaboration with other professionals, and behavioral health interventions. Psychosocial factors such as stress, anger, anxiety, and depression promote heart disease. Alternately, the use of mood-enhancing or stress-reducing techniques--such as optimism, meditation, counseling, exercise, and imagery--as well as a lifestyle behavioral change approach can have a positive effect on reducing the incidence of heart disease. Behavioral health treatment can improve medical conditions and quality of life.

  12. Women's connectivity in extreme networks.

    PubMed

    Manrique, Pedro; Cao, Zhenfeng; Gabriel, Andrew; Horgan, John; Gill, Paul; Qi, Hong; Restrepo, Elvira M; Johnson, Daniela; Wuchty, Stefan; Song, Chaoming; Johnson, Neil

    2016-06-01

    A popular stereotype is that women will play more minor roles than men as environments become more dangerous and aggressive. Our analysis of new longitudinal data sets from offline and online operational networks [for example, ISIS (Islamic State)] shows that although men dominate numerically, women emerge with superior network connectivity that can benefit the underlying system's robustness and survival. Our observations suggest new female-centric approaches that could be used to affect such networks. They also raise questions about how individual contributions in high-pressure systems are evaluated. PMID:27386564

  13. Generalized magnetofluid connections in pair plasmas

    NASA Astrophysics Data System (ADS)

    Asenjo, Felipe A.; Comisso, Luca; Mahajan, Swadesh M.

    2015-12-01

    We extend the magnetic connection theorem of ideal magnetohydrodynamics to nonideal relativistic pair plasmas. Adopting a generalized Ohm's law, we prove the existence of generalized magnetofluid connections that are preserved by the plasma dynamics. We show that these connections are related to a general antisymmetric tensor that unifies the electromagnetic and fluid fields. The generalized magnetofluid connections set important constraints on the plasma dynamics by forbidding transitions between configurations with different magnetofluid connectivity. An approximated solution is explicitly shown where the corrections due to current inertial effects are found.

  14. Generalized magnetofluid connections in pair plasmas

    SciTech Connect

    Asenjo, Felipe A.; Comisso, Luca; Mahajan, Swadesh M.

    2015-12-15

    We extend the magnetic connection theorem of ideal magnetohydrodynamics to nonideal relativistic pair plasmas. Adopting a generalized Ohm's law, we prove the existence of generalized magnetofluid connections that are preserved by the plasma dynamics. We show that these connections are related to a general antisymmetric tensor that unifies the electromagnetic and fluid fields. The generalized magnetofluid connections set important constraints on the plasma dynamics by forbidding transitions between configurations with different magnetofluid connectivity. An approximated solution is explicitly shown where the corrections due to current inertial effects are found.

  15. Interrogating Texts: From Deferent to Efferent and Aesthetic Reading Practices

    ERIC Educational Resources Information Center

    Smith, Cheryl Hogue

    2012-01-01

    This article offers a revised version of transactional reading theory to explain how students classified as basic writers tend to employ counterproductive reading and thinking processes that inhibit them from full participation in academic life. Louise Rosenblatt proposes that readers have two main positions or purposes in reading--the efferent…

  16. Characteristics, specificity, and efferent control of frog cutaneous cold receptors.

    PubMed

    Spray, D C

    1974-02-01

    1. Thermal stimulation of frog skin produces a discharge in afferents in the dorsocutaneous nerve. The characteristics of this response have been examined with regard to static and dynamic sensitivity to thermal stimuli and to mechanical sensitivity. Frog cutaneous receptors respond only to cooling, with no response to warming through the same thermal range.2. The static temperature at which these receptors are maximally active is about 24 degrees C for Rana pipiens and about 27 degrees C for R. catesbiana.3. The dynamic sensitivity of frog cutaneous receptors is linearly related to both stimulus slope and magnitude. Maximum dynamic sensitivity was between -90 and -120 impulses/ degrees C.sec.4. Antidromic occlusion experiments demonstrate relative insensitivity of these receptors to tonic mechanical stimulation. At high stimulus intensities, however, larger fibres are recruited into the response; this recruitment of action potentials of larger amplitude is a linear function of both stimulus slope and magnitude.5. Spike heights are linearly related to conduction velocities in the dorsocutaneous nerve; tonic mechanoreceptors have a mean spike height of 28.4+/-0.6 muV and conduction velocities about 6-8 m/sec, whereas these temperature sensitive receptors have spike heights 15.8+/-0.4 muV and conduction velocities about 3-4 m/sec.6. Maximum dynamic sensitivity skin is increased following stimulation of the first or second sympathetic ganglion. This increase is both marked and progressive, reaching a maximal enhancement of about 150-160% control at a stimulus rate of 5 stimuli/train, each train delivered once every 5 sec.7. Static sensitivity of the cold receptors is also increased following sympathetic stimulation. This increased sensitivity is shown by both increased discharge rate within the same thermal range and by decreased temperature of maximum static sensitivity.8. Sympathetic modulation of dynamic thermal sensitivity is mimicked by epinephrine and norepinephrine in doses of 10(-6)-10(-7) g/ml. Ephedrine, another adrenergic agonist, also mimics the enhancement of cold receptors by sympathetic stimulation.9. Larger fibres are recruited to account for the increased sensitivity of thermoreceptors following sympathetic stimulation and epinephrine application.10. Propranolol and phentolamine both block the enhancement of the response by sympathetic stimulation, but propranolol blocks the response of the receptor to thermal stimulation as well. Reserpine pre-treatment blocks the effect of sympathetic stimulation on the cold response. PMID:4545023

  17. Orexin neurons suppress narcolepsy via 2 distinct efferent pathways.

    PubMed

    Hasegawa, Emi; Yanagisawa, Masashi; Sakurai, Takeshi; Mieda, Michihiro

    2014-02-01

    The loss of orexin neurons in humans is associated with the sleep disorder narcolepsy, which is characterized by excessive daytime sleepiness and cataplexy. Mice lacking orexin peptides, orexin neurons, or orexin receptors recapitulate human narcolepsy phenotypes, further highlighting a critical role for orexin signaling in the maintenance of wakefulness. Despite the known role of orexin neurons in narcolepsy, the precise neural mechanisms downstream of these neurons remain unknown. We found that targeted restoration of orexin receptor expression in the dorsal raphe (DR) and in the locus coeruleus (LC) of mice lacking orexin receptors inhibited cataplexy-like episodes and pathological fragmentation of wakefulness (i.e., sleepiness), respectively. The suppression of cataplexy-like episodes correlated with the number of serotonergic neurons restored with orexin receptor expression in the DR, while the consolidation of fragmented wakefulness correlated with the number of noradrenergic neurons restored in the LC. Furthermore, pharmacogenetic activation of these neurons using designer receptor exclusively activated by designer drug (DREADD) technology ameliorated narcolepsy in mice lacking orexin neurons. These results suggest that DR serotonergic and LC noradrenergic neurons play differential roles in orexin neuron-dependent regulation of sleep/wakefulness and highlight a pharmacogenetic approach for the amelioration of narcolepsy.

  18. Orexin neurons suppress narcolepsy via 2 distinct efferent pathways

    PubMed Central

    Hasegawa, Emi; Yanagisawa, Masashi; Sakurai, Takeshi; Mieda, Michihiro

    2014-01-01

    The loss of orexin neurons in humans is associated with the sleep disorder narcolepsy, which is characterized by excessive daytime sleepiness and cataplexy. Mice lacking orexin peptides, orexin neurons, or orexin receptors recapitulate human narcolepsy phenotypes, further highlighting a critical role for orexin signaling in the maintenance of wakefulness. Despite the known role of orexin neurons in narcolepsy, the precise neural mechanisms downstream of these neurons remain unknown. We found that targeted restoration of orexin receptor expression in the dorsal raphe (DR) and in the locus coeruleus (LC) of mice lacking orexin receptors inhibited cataplexy-like episodes and pathological fragmentation of wakefulness (i.e., sleepiness), respectively. The suppression of cataplexy-like episodes correlated with the number of serotonergic neurons restored with orexin receptor expression in the DR, while the consolidation of fragmented wakefulness correlated with the number of noradrenergic neurons restored in the LC. Furthermore, pharmacogenetic activation of these neurons using designer receptor exclusively activated by designer drug (DREADD) technology ameliorated narcolepsy in mice lacking orexin neurons. These results suggest that DR serotonergic and LC noradrenergic neurons play differential roles in orexin neuron–dependent regulation of sleep/wakefulness and highlight a pharmacogenetic approach for the amelioration of narcolepsy. PMID:24382351

  19. Evaluation of the Demonstration Sites in the ConnectEd Network

    ERIC Educational Resources Information Center

    Farr, Beverly; Bradby, Denise; Hartry, Ardice; Sipes, Laurel; Hall, Leslie; Tasoff, Shayna

    2009-01-01

    In California, the James Irvine Foundation created ConnectEd: The California Center for College and Career to promote multiple pathways that link to the state's 15 major industry sectors. The ConnectEd Network of Schools, a demonstration project supported by Irvine, plays a critical role in expanding student options through multiple pathways and…

  20. Tieback connection method and apparatus

    SciTech Connect

    Watkins, B.J.

    1984-06-26

    A tieback connection apparatus effects a metal-to-metal type seal between a riser run from an overhead vessel and a subsea well casing suspended from a casing hanger in a subsea wellhead member. The apparatus includes a tubular mandrel connected to and run by the riser into the wellhead, and a metal-to-metal type annular seal mounted at the lower end of the mandrel. The end of the mandrel is positioned in coaxial alignment with the casing hanger with the seal ring position between the mandrel and the hanger to effect a seal between the riser and the casing when compressive force is applied to the seal ring. A seal activating mechanism, associated with the mandrel and operated by a tool run from the vessel, engages the casing hanger and applies the compressive force to effect the seal. The seal activating mechanism includes a locking collet, a reaction sleeve, and a drive sleeve. Rotation of the drive sleeve by the operating tool moves the reaction sleeve into contact with the collet to maintain locking engagement between the casing hanger and the collet. The collet also prevents further movement of the reaction sleeve whereby further rotation of the drive sleeve causes the reaction sleeve to apply the compressive force to the mandrel, seal ring and casing hanger. A method is also provided for effecting a metal-to-metal type seal between the riser and the casing.

  1. Astrophysicists’ Conversational Connections on Twitter

    PubMed Central

    Holmberg, Kim; Bowman, Timothy D.; Haustein, Stefanie; Peters, Isabella

    2014-01-01

    Because Twitter and other social media are increasingly used for analyses based on altmetrics, this research sought to understand what contexts, affordance use, and social activities influence the tweeting behavior of astrophysicists. Thus, the presented study has been guided by three research questions that consider the influence of astrophysicists’ activities (i.e., publishing and tweeting frequency) and of their tweet construction and affordance use (i.e. use of hashtags, language, and emotions) on the conversational connections they have on Twitter. We found that astrophysicists communicate with a variety of user types (e.g. colleagues, science communicators, other researchers, and educators) and that in the ego networks of the astrophysicists clear groups consisting of users with different professional roles can be distinguished. Interestingly, the analysis of noun phrases and hashtags showed that when the astrophysicists address the different groups of very different professional composition they use very similar terminology, but that they do not talk to each other (i.e. mentioning other user names in tweets). The results also showed that in those areas of the ego networks that tweeted more the sentiment of the tweets tended to be closer to neutral, connecting frequent tweeting with information sharing activities rather than conversations or expressing opinions. PMID:25153196

  2. Nonlinear connectivity by Granger causality.

    PubMed

    Marinazzo, Daniele; Liao, Wei; Chen, Huafu; Stramaglia, Sebastiano

    2011-09-15

    The communication among neuronal populations, reflected by transient synchronous activity, is the mechanism underlying the information processing in the brain. Although it is widely assumed that the interactions among those populations (i.e. functional connectivity) are highly nonlinear, the amount of nonlinear information transmission and its functional roles are not clear. The state of the art to understand the communication between brain systems are dynamic causal modeling (DCM) and Granger causality. While DCM models nonlinear couplings, Granger causality, which constitutes a major tool to reveal effective connectivity, and is widely used to analyze EEG/MEG data as well as fMRI signals, is usually applied in its linear version. In order to capture nonlinear interactions between even short and noisy time series, a few approaches have been proposed. We review them and focus on a recently proposed flexible approach has been recently proposed, consisting in the kernel version of Granger causality. We show the application of the proposed approach on EEG signals and fMRI data.

  3. Random geometric graphs with general connection functions.

    PubMed

    Dettmann, Carl P; Georgiou, Orestis

    2016-03-01

    In the original (1961) Gilbert model of random geometric graphs, nodes are placed according to a Poisson point process, and links formed between those within a fixed range. Motivated by wireless ad hoc networks "soft" or "probabilistic" connection models have recently been introduced, involving a "connection function" H(r) that gives the probability that two nodes at distance r are linked (directly connect). In many applications (not only wireless networks), it is desirable that the graph is connected; that is, every node is linked to every other node in a multihop fashion. Here the connection probability of a dense network in a convex domain in two or three dimensions is expressed in terms of contributions from boundary components for a very general class of connection functions. It turns out that only a few quantities such as moments of the connection function appear. Good agreement is found with special cases from previous studies and with numerical simulations. PMID:27078372

  4. Hematopoietic stem cell origin of connective tissues.

    PubMed

    Ogawa, Makio; Larue, Amanda C; Watson, Patricia M; Watson, Dennis K

    2010-07-01

    Connective tissue consists of "connective tissue proper," which is further divided into loose and dense (fibrous) connective tissues and "specialized connective tissues." Specialized connective tissues consist of blood, adipose tissue, cartilage, and bone. In both loose and dense connective tissues, the principal cellular element is fibroblasts. It has been generally believed that all cellular elements of connective tissue, including fibroblasts, adipocytes, chondrocytes, and bone cells, are generated solely by mesenchymal stem cells. Recently, a number of studies, including those from our laboratory based on transplantation of single hematopoietic stem cells, strongly suggested a hematopoietic stem cell origin of these adult mesenchymal tissues. This review summarizes the experimental evidence for this new paradigm and discusses its translational implications.

  5. Radiotherapy in patients with connective tissue diseases.

    PubMed

    Giaj-Levra, Niccolò; Sciascia, Savino; Fiorentino, Alba; Fersino, Sergio; Mazzola, Rosario; Ricchetti, Francesco; Roccatello, Dario; Alongi, Filippo

    2016-03-01

    The decision to offer radiotherapy in patients with connective tissue diseases continues to be challenging. Radiotherapy might trigger the onset of connective tissue diseases by increasing the expression of self-antigens, diminishing regulatory T-cell activity, and activating effectors of innate immunity (dendritic cells) through Toll-like receptor-dependent mechanisms, all of which could potentially lead to breaks of immune tolerance. This potential risk has raised some debate among radiation oncologists about whether patients with connective tissue diseases can tolerate radiation as well as people without connective tissue diseases. Because the number of patients with cancer and connective tissue diseases needing radiotherapy will probably increase due to improvements in medical treatment and longer life expectancy, the issue of interactions between radiotherapy and connective tissue diseases needs to be clearer. In this Review, we discuss available data and evidence for patients with connective tissue diseases treated with radiotherapy.

  6. Random geometric graphs with general connection functions

    NASA Astrophysics Data System (ADS)

    Dettmann, Carl P.; Georgiou, Orestis

    2016-03-01

    In the original (1961) Gilbert model of random geometric graphs, nodes are placed according to a Poisson point process, and links formed between those within a fixed range. Motivated by wireless ad hoc networks "soft" or "probabilistic" connection models have recently been introduced, involving a "connection function" H (r ) that gives the probability that two nodes at distance r are linked (directly connect). In many applications (not only wireless networks), it is desirable that the graph is connected; that is, every node is linked to every other node in a multihop fashion. Here the connection probability of a dense network in a convex domain in two or three dimensions is expressed in terms of contributions from boundary components for a very general class of connection functions. It turns out that only a few quantities such as moments of the connection function appear. Good agreement is found with special cases from previous studies and with numerical simulations.

  7. Connectivity in Autism: A review of MRI connectivity studies

    PubMed Central

    Rane, Pallavi; Cochran, David; Hodge, Steven M.; Haselgrove, Christian; Kennedy, David; Frazier, Jean A.

    2016-01-01

    Autism Spectrum Disorder (ASD) affects 1 in 50 children between the ages of 6–17 years as per a 2012 CDC survey of parents. The etiology of ASD is not precisely known. ASD is an umbrella term, which includes low (IQ<70) to high functioning (IQ>70) individuals. A better understanding of the disorder, and how it manifests in an individual subject can lead to more effective intervention plans to fulfill the individual’s treatment needs. Magnetic resonance imaging (MRI) is a non-invasive investigational tool that can help study the ways in which the brain develops and/or deviates from the typical developmental trajectory. MRI offers insights into the structure, function, and metabolism of the brain. In this article, we review published studies on brain connectivity changes in ASD using either resting state functional MRI or diffusion tensor imaging. The general findings of decreases in white matter integrity and long-range neural coherence are prevalent in ASD literature. However, there is somewhat less of a consensus in the detailed localization of these findings. There are even fewer studies linking these connectivity alterations with the behavioral phenotype of the disorder. Nevertheless, with the help of data sharing and large-scale analytic efforts, the field is advancing towards several convergent themes. These include reduced functional coherence of long-range intra-hemispheric cortico-cortical default mode circuitry, impaired inter-hemispheric regulation, and an associated, perhaps compensatory, increase in local and short-range cortico-subcortical coherence. PMID:26146755

  8. Connecting multimodality in human communication

    PubMed Central

    Regenbogen, Christina; Habel, Ute; Kellermann, Thilo

    2013-01-01

    A successful reciprocal evaluation of social signals serves as a prerequisite for social coherence and empathy. In a previous fMRI study we studied naturalistic communication situations by presenting video clips to our participants and recording their behavioral responses regarding empathy and its components. In two conditions, all three channels transported congruent emotional or neutral information, respectively. Three conditions selectively presented two emotional channels and one neutral channel and were thus bimodally emotional. We reported channel-specific emotional contributions in modality-related areas, elicited by dynamic video clips with varying combinations of emotionality in facial expressions, prosody, and speech content. However, to better understand the underlying mechanisms accompanying a naturalistically displayed human social interaction in some key regions that presumably serve as specific processing hubs for facial expressions, prosody, and speech content, we pursued a reanalysis of the data. Here, we focused on two different descriptions of temporal characteristics within these three modality-related regions [right fusiform gyrus (FFG), left auditory cortex (AC), left angular gyrus (AG) and left dorsomedial prefrontal cortex (dmPFC)]. By means of a finite impulse response (FIR) analysis within each of the three regions we examined the post-stimulus time-courses as a description of the temporal characteristics of the BOLD response during the video clips. Second, effective connectivity between these areas and the left dmPFC was analyzed using dynamic causal modeling (DCM) in order to describe condition-related modulatory influences on the coupling between these regions. The FIR analysis showed initially diminished activation in bimodally emotional conditions but stronger activation than that observed in neutral videos toward the end of the stimuli, possibly by bottom-up processes in order to compensate for a lack of emotional information. The

  9. The Interaction-Activity Connection

    NASA Technical Reports Server (NTRS)

    Borne, Kirk D.

    1996-01-01

    A review is presented of the numerous studies that have been undertaken to investigate the likely interaction-activity connection among galaxies. Both observational evidence and theoretical supporting models are reviewed. Some specific examples of "interactive" galaxies from the author's own research are presented: (a) the collision-induced AGN (Active Galactic Nuclei) activity in the radio jet source 3C278; and (b) the collision-induced starburst activity in the spectacular "Cartwheel" ring galaxy. Some comments are offered concerning some of the more promising theoretical investigations that are now taking place. A few words of warning are also offered about the possible misinterpretation of putative collision-induced morphologies among some galaxy samples.

  10. Unity connecting module in SSPF

    NASA Technical Reports Server (NTRS)

    1998-01-01

    In the Space Station Processing Facility, the Unity connecting module, part of the International Space Station, is shown with Pressurized Mating Adapters 1 (left) and 2 (right) attached. Unity is scheduled to undergo testing of the common berthing mechanism to which other space station elements will dock. Unity is the primary payload on mission STS-88, targeted to launch Dec. 3, 1998. Other testing includes the Pad Demonstration Test to verify the compatibility of the module with the Space Shuttle as well as the ability of the astronauts to send and receive commands to Unity from the flight deck of the orbiter. Unity is expected to be ready for installation into the payload canister on Oct. 25, and transported to Launch Pad 39-A on Oct. 27. The Unity will be mated to the Russian-built Zarya control module which should already be in orbit at that time.

  11. Real World Connections Through Videoconferences

    NASA Technical Reports Server (NTRS)

    Peterson, Ruth; Lytle, John (Technical Monitor)

    2002-01-01

    The Learning Technologies Project (LTP) is a partner in the National Aeronautics and Space Administration's (NASA's) educational technology program unit, an electronic community center that fosters interaction, collaboration, and sharing among educators, learners, and scientists. The goal of the NASA Glenn Research Center's Learning Technologies Project is to increase students' interest and proficiency in mathematics, science, and technology through the use of computing and communications technology and by using NASA's mission in aerospace technology as a theme. The primary components are: (1) Beginner's Guide to Aeronautics, including interactive simulation packages and teacher-created online activities. (2) NASA Virtual Visits, videoconferences (with online pre-post-conference activities) connecting students and teachers to NASA scientists and researchers.

  12. Method for hermetic electrical connections

    DOEpatents

    Monroe, Saundra L.; Glass, S. Jill; Stone, Ronnie G.; Bond, Jamey T.; Susan, Donald F.

    2011-12-27

    A method of providing a hermetic, electrical connection between two electrical components by mating at least one metal pin in a glass-ceramic to metal seal connector to two electrical components, wherein the glass-ceramic to metal seal connector incorporates at least one metal pin encased (sealed) in a glass-ceramic material inside of a metal housing, with the glass-ceramic material made from 65-80% SiO.sub.2, 8-16% Li.sub.2O, 2-8% Al.sub.2O.sub.3, 1-5% P.sub.2O.sub.5, 1-8% K.sub.2O, 0.5-7% B.sub.2O.sub.3, and 0-5% ZnO. The connector retains hermeticity at temperatures as high as 700.degree. C. and pressures as high as 500 psi.

  13. Delta connected resonant snubber circuit

    DOEpatents

    Lai, J.S.; Peng, F.Z.; Young, R.W. Sr.; Ott, G.W. Jr.

    1998-01-20

    A delta connected, resonant snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the dc supply voltage through the main inverter switches and the auxiliary switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter. 36 figs.

  14. Delta connected resonant snubber circuit

    DOEpatents

    Lai, Jih-Sheng; Peng, Fang Zheng; Young, Sr., Robert W.; Ott, Jr., George W.

    1998-01-01

    A delta connected, resonant snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the dc supply voltage through the main inverter switches and the auxiliary switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter.

  15. Structural Connectivity of the Developing Human Amygdala

    PubMed Central

    Saygin, Zeynep M.; Osher, David E.; Koldewyn, Kami; Martin, Rebecca E.; Finn, Amy; Saxe, Rebecca; Gabrieli, John D.E.; Sheridan, Margaret

    2015-01-01

    A large corpus of research suggests that there are changes in the manner and degree to which the amygdala supports cognitive and emotional function across development. One possible basis for these developmental differences could be the maturation of amygdalar connections with the rest of the brain. Recent functional connectivity studies support this conclusion, but the structural connectivity of the developing amygdala and its different nuclei remains largely unstudied. We examined age related changes in the DWI connectivity fingerprints of the amygdala to the rest of the brain in 166 individuals of ages 5-30. We also developed a model to predict age based on individual-subject amygdala connectivity, and identified the connections that were most predictive of age. Finally, we segmented the amygdala into its four main nucleus groups, and examined the developmental changes in connectivity for each nucleus. We observed that with age, amygdalar connectivity becomes increasingly sparse and localized. Age related changes were largely localized to the subregions of the amygdala that are implicated in social inference and contextual memory (the basal and lateral nuclei). The central nucleus’ connectivity also showed differences with age but these differences affected fewer target regions than the basal and lateral nuclei. The medial nucleus did not exhibit any age related changes. These findings demonstrate increasing specificity in the connectivity patterns of amygdalar nuclei across age. PMID:25875758

  16. Brain Connectivity in Autism Spectrum Disorder

    PubMed Central

    Mohammad-Rezazadeh, Iman; Frohlich, Joel; Loo, Sandra K.; Jeste, Shafali S.

    2016-01-01

    Purpose of review Many studies have reported that individuals with autism spectrum disorder (ASD) have different brain connectivity patterns compared to typically developing individuals. However, the results of more recent studies do not unanimously support the traditional view in which individuals with ASD have lower connectivity between distal brain regions and increased connectivity within proximal brain regions. In this review, we discuss different methods for measuring brain connectivity and how the use of different metrics may contribute to the lack of convergence of investigations of connectivity in ASD. Recent findings The discrepancy in brain connectivity results across studies may be due to important methodological factors such as the connectivity measure applied, the age of patients studied, the brain region(s) examined, and the time interval and frequency band(s) in which connectivity was analyzed. Summary We conclude that more sophisticated EEG analytic approaches should be utilized to more accurately infer causation and directionality of information transfer between brain regions, which may show dynamic changes of functional connectivity in the brain. Moreover, further investigations of connectivity with respect to behavior and clinical phenotype are needed to probe underlying brain networks implicated in core deficits of ASD. PMID:26910484

  17. Structural connectivity of the developing human amygdala.

    PubMed

    Saygin, Zeynep M; Osher, David E; Koldewyn, Kami; Martin, Rebecca E; Finn, Amy; Saxe, Rebecca; Gabrieli, John D E; Sheridan, Margaret

    2015-01-01

    A large corpus of research suggests that there are changes in the manner and degree to which the amygdala supports cognitive and emotional function across development. One possible basis for these developmental differences could be the maturation of amygdalar connections with the rest of the brain. Recent functional connectivity studies support this conclusion, but the structural connectivity of the developing amygdala and its different nuclei remains largely unstudied. We examined age related changes in the DWI connectivity fingerprints of the amygdala to the rest of the brain in 166 individuals of ages 5-30. We also developed a model to predict age based on individual-subject amygdala connectivity, and identified the connections that were most predictive of age. Finally, we segmented the amygdala into its four main nucleus groups, and examined the developmental changes in connectivity for each nucleus. We observed that with age, amygdalar connectivity becomes increasingly sparse and localized. Age related changes were largely localized to the subregions of the amygdala that are implicated in social inference and contextual memory (the basal and lateral nuclei). The central nucleus' connectivity also showed differences with age but these differences affected fewer target regions than the basal and lateral nuclei. The medial nucleus did not exhibit any age related changes. These findings demonstrate increasing specificity in the connectivity patterns of amygdalar nuclei across age. PMID:25875758

  18. Evoked Effective Connectivity of the Human Neocortex

    PubMed Central

    Entz, László; Tóth, Emília; Keller, Corey J.; Bickel, Stephan; Groppe, David M.; Fabó, Dániel; Kozák, Lajos R.; Eroőss, Loránd; Ulbert, István; Mehta, Ashesh D.

    2016-01-01

    The role of cortical connectivity in brain function and pathology is increasingly being recognized. While in vivo magnetic resonance imaging studies have provided important insights into anatomical and functional connectivity, these methodologies are limited in their ability to detect electrophysiological activity and the causal relationships that underlie effective connectivity. Here, we describe results of cortico-cortical evoked potential (CCEP) mapping using single pulse electrical stimulation in 25 patients undergoing seizure monitoring with subdural electrode arrays. Mapping was performed by stimulating adjacent electrode pairs and recording CCEPs from the remainder of the electrode array. CCEPs reliably revealed functional networks and showed an inverse relationship to distance between sites. Coregistration to Brodmann areas (BA) permitted group analysis. Connections were frequently directional with 43% of early responses and 50% of late responses of connections reflecting relative dominance of incoming or outgoing connections. The most consistent connections were seen as outgoing from motor cortex, BA6–BA9, somatosensory (SS) cortex, anterior cingulate cortex, and Broca's area. Network topology revealed motor, SS, and premotor cortices along with BA9 and BA10 and language areas to serve as hubs for cortical connections. BA20 and BA39 demonstrated the most consistent dominance of outdegree connections, while BA5, BA7, auditory cortex, and anterior cingulum demonstrated relatively greater indegree. This multicenter, large-scale, directional study of local and long-range cortical connectivity using direct recordings from awake, humans will aid the interpretation of noninvasive functional connectome studies. PMID:25044884

  19. [Connective tissue and prolapse genesis].

    PubMed

    Tremollieres, F

    2010-06-01

    The pathophysiology of pelvic floor disorders still remains not well understood. Increasing age as well as vaginal multiparity are the main commonly accepted factors. The hypothesis of a defect of connective tissues of the pelvic floor with aging due to collagen deficiency and/or elastic fiber degradation is often highlighted. The issue of a potential protective role of HRT is also discussed although the recent results from the WHI would suggest a negative impact of HRT on urinary incontinence, especially when HRT is initiated in elderly women, far from the menopause. Nevertheless, environmental factors cannot explain the full pathogenesis of pelvic organ prolapse (POP) and the contribution of genetic factors to the development of pelvic floor disorders is widely recognized. Support for a genetic influence on POP derives from reports suggesting that heritability is a strong contributing factor and a familial history of POP is considered as a classical risk factor. However, the characterization of the underlying molecular mechanisms remains limited, since POP may be considered the end result of a multifactorial process leading to destruction of vaginal wall connective tissue. Experimental studies in mice with null mutations in the genes encoding different putative factors involved in elastic fibers remodeling and homeostasis are crucial in the understanding of the pathogenesis of POP. Mice with null mutation in the gene encoding lysyl oxidase-like 1 (LOXL1) or fibulin-5, demonstrate signs of elastinopathy including the development of a POP in the postpartum. Likewise, homeobox genes such as HOXA11, which are essential in the embryonic development of the urogenital tract might also be involved in the pathogenesis of POP. The better understanding of the underlying determinants of pelvic floor disorders with a special focus on genetic factors may offer new therapeutic strategies, in addition to or replacement of surgical procedures.

  20. Boundary effects in welded steel moment connections

    NASA Astrophysics Data System (ADS)

    Lee, Kyoung-Hyeog

    Unprecedented widespread failure of welded moment connections in steel frames caused by the 1994 Northridge and the 1995 Kobe earthquakes have alarmed the engineering communities throughout the world. Welded moment connections in steel frames have been traditionally designed by using the classical beam theory which leads to assumptions that the flanges transfer moment while the web connection primarily resists the shear force. However, this study shows that the magnitude and direction of the principal stresses in the connection region are better approximated by using truss analogy rather than the classical beam theory. Accordingly, both the bending moment and the shear force are transferred across the connection near the beam flanges through diagonal strut action. Thus, the beam flange region of the traditionally designed connection is overloaded. This conclusion explains, to a large extent, the recently observed steel moment connection failures. In this study, detailed finite element analyses were carried out for a representative beam-to-column subassemblage with fully welded connection. The stress distribution in the beam web and flanges in the vicinity of the connection were closely studied. The factors responsible for stress redistribution and concentration were identified by using fundamental principles of mechanics. It was concluded that peak resultant stresses can exceed the values used in simple design calculations by large margins. Using the finite element analysis results and the truss analogy to establish a realistic load path in the connection, a practical and more rational analysis and design procedure was developed. The proposed design procedure and the new connection details were successfully validated through cyclic load testing of a nearly full size specimen. The truss model represented the force transmission around the beam-to-column moment connection region very well. Results of the finite element analyses and the laboratory testing showed

  1. Changes in Effective Connectivity by Propofol Sedation

    PubMed Central

    Soddu, Andrea; Boly, Melanie; Boveroux, Pierre; Vanhaudenhuyse, Audrey; Bruno, Marie-Aurélie; Gosseries, Olivia; Bonhomme, Vincent; Laureys, Steven; Noirhomme, Quentin

    2013-01-01

    Mechanisms of propofol-induced loss of consciousness remain poorly understood. Recent fMRI studies have shown decreases in functional connectivity during unconsciousness induced by this anesthetic agent. Functional connectivity does not provide information of directional changes in the dynamics observed during unconsciousness. The aim of the present study was to investigate, in healthy humans during an auditory task, the changes in effective connectivity resulting from propofol induced loss of consciousness. We used Dynamic Causal Modeling for fMRI (fMRI-DCM) to assess how causal connectivity is influenced by the anesthetic agent in the auditory system. Our results suggest that the dynamic observed in the auditory system during unconsciousness induced by propofol, can result in a mixture of two effects: a local inhibitory connectivity increase and a decrease in the effective connectivity in sensory cortices. PMID:23977030

  2. Thermally effective, electrically isolating heat intercept connections

    SciTech Connect

    Niemann, R.C.; Gonczy, J.D.; Nicol, T.H.

    1995-06-01

    Electrical and electronic equipment often require thermally effective beat intercept connections that provide electrical isolation. Such connections can be developed by clamping, with a thermal-interference fit, an electrically insulating cylindrical tube between a central disk and an outer ring. Heat flows radially through the disk-tube-ring assembly. Thermal effectiveness, i.e., {Delta}T for a given heat flux, and electrical isolation are controlled by tube geometry and material and by connection-assembly details. Connections of this type are being developed as cryogenic heat intercepts for electrical current leads that employ high-temperature superconductors. We discuss the design considerations and details of a beat intercept connection that transfers a 45-w thermal load at 60 K with a {Delta}T of {approx} 10 K while providing 7.5 kV electrical isolation. Prototype heat intercept connections have been evaluated for their thermal and electrical performance, and the results are presented.

  3. Connectivity analysis of controlled quantum systems

    NASA Astrophysics Data System (ADS)

    Wu, Rong; Rabitz, Herschel; Turinici, Gabriel; Sola, Ignacio

    2004-11-01

    A connectivity analysis of controlled quantum systems assesses the feasibility of a field existing that can transfer at least some amplitude between any specified pair of states. Although Hamiltonians with special structure or symmetry may not produce full connectivity, it is argued and demonstrated that virtually any Hamiltonian is expected to be connected. The connectivity of any particular system is generally revealed in the quantum evolution over a single or at most a few time steps. A connectivity analysis is inexpensive to perform and it can also identify statistically significant intermediate states linking a specified initial and final state. These points are illustrated with several simple systems. The likelihood of an arbitrary system being connected implies that at least some product yield can be expected in the laboratory for virtually all systems subjected to a suitable control.

  4. Projective Connections and the Algebra of Densities

    SciTech Connect

    George, Jacob

    2008-11-18

    Projective connections first appeared in Cartan's papers in the 1920's. Since then they have resurfaced periodically in, for example, integrable systems and perhaps most recently in the context of so called projectively equivariant quantisation. We recall the notion of projective connection and describe its relation with the algebra of densities on a manifold. In particular, we construct a Laplace-type operator on functions using a Thomas projective connection and a symmetric contravariant tensor of rank 2 ('upper metric')

  5. Assembly design system based on engineering connection

    NASA Astrophysics Data System (ADS)

    Yin, Wensheng

    2016-05-01

    An assembly design system is an important part of computer-aided design systems, which are important tools for realizing product concept design. The traditional assembly design system does not record the connection information of production on the engineering layer; consequently, the upstream design idea cannot be fully used in the downstream design. An assembly design model based on the relationship of engineering connection is presented. In this model, all nodes are divided into two categories: The component and the connection. Moreover, the product is constructed on the basis of the connection relationship of the components. The model is an And/Or graph and has the ability to record all assembly schemes. This model records only the connection information that has engineering application value in the product design. In addition, this model can significantly reduce the number of combinations, and is very favorable for the assembly sequence planning in the downstream. The system contains a connection knowledge system that can be mapped to the connection node, and the connection knowledge obtained in practice can be returned to the knowledge system. Finally, VC++ 6.0 is used to develop a prototype system called Connect-based Assembly Planning (CAP). The relationship between the CAP system and the commercial assembly design system is also established.

  6. Further advances in deepwater flowline connection technology

    SciTech Connect

    Moreira, J.R.; Cerqueira, M.B.; Silva, G.J.R.; Nagle, R.J.

    1996-12-31

    A diverless guidelineless flowline connection system, the so-called direct vertical connection, has been developed, and tested, which sharply decreases connection time, while allowing the lay-vessel itself to perform both flowline ends connections, thus dispensing with the use of auxiliary tools and making the operation more cost effective and reliable. This system has been designed to overcome problems associated with conventional pull-in systems, the lay-away method, ROV assisted pull-in systems and conventional vertical connections. The former have already been successfully used in Marlim field, in 25 wells located at water depths ranging from 740 m to 980 m. The direct vertical connection can now be considered a field proven method. Five import flowline connections have already been successfully performed in Albacora field manifold, installed at 620 m water depth. From now on, based on the excellent results achieved from those installations and previous tests, all deepwater Brazilian subsea trees and manifolds will be designed for direct vertical connection. Sixty six trees and six manifolds incorporating the direct vertical connection system are presently under fabrication in Brazil.

  7. Neural Field Dynamics with Heterogeneous Connection Topology

    NASA Astrophysics Data System (ADS)

    Qubbaj, Murad R.; Jirsa, Viktor K.

    2007-06-01

    Neural fields receive inputs from local and nonlocal sources. Notably in a biologically realistic architecture the latter vary under spatial translations (heterogeneous), the former do not (homogeneous). To understand the mutual effects of homogeneous and heterogeneous connectivity, we study the stability of the steady state activity of a neural field as a function of its connectivity and transmission speed. We show that myelination, a developmentally relevant change of the heterogeneous connectivity, always results in the stabilization of the steady state via oscillatory instabilities, independent of the local connectivity. Nonoscillatory instabilities are shown to be independent of any influences of time delay.

  8. Critical Connections: Health and Academics

    PubMed Central

    Michael, Shannon L; Merlo, Caitlin L; Basch, Charles E; Wentzel, Kathryn R; Wechsler, Howell

    2015-01-01

    BACKGROUND While it is a national priority to support the health and education of students, these sectors must better align, integrate, and collaborate to achieve this priority. This article summarizes the literature on the connection between health and academic achievement using the Whole School, Whole Community, and Whole Child (WSCC) framework as a way to address health-related barriers to learning. METHODS A literature review was conducted on the association between student health and academic achievement. RESULTS Most of the evidence examined the association between student health behaviors and academic achievement, with physical activity having the most published studies and consistent findings. The evidence supports the need for school health services by demonstrating the association between chronic conditions and decreased achievement. Safe and positive school environments were associated with improved health behaviors and achievement. Engaging families and community members in schools also had a positive effect on students' health and achievement. CONCLUSIONS Schools can improve the health and learning of students by supporting opportunities to learn about and practice healthy behaviors, providing school health services, creating safe and positive school environments, and engaging families and community. This evidence supports WSCC as a potential framework for achieving national educational and health goals. PMID:26440816

  9. Tweaking synchronization by connectivity modifications

    NASA Astrophysics Data System (ADS)

    Schultz, Paul; Peron, Thomas; Eroglu, Deniz; Stemler, Thomas; Ramírez Ávila, Gonzalo Marcelo; Rodrigues, Francisco A.; Kurths, Jürgen

    2016-06-01

    Natural and man-made networks often possess locally treelike substructures. Taking such tree networks as our starting point, we show how the addition of links changes the synchronization properties of the network. We focus on two different methods of link addition. The first method adds single links that create cycles of a well-defined length. Following a topological approach, we introduce cycles of varying length and analyze how this feature, as well as the position in the network, alters the synchronous behavior. We show that in particular short cycles can lead to a maximum change of the Laplacian's eigenvalue spectrum, dictating the synchronization properties of such networks. The second method connects a certain proportion of the initially unconnected nodes. We simulate dynamical systems on these network topologies, with the nodes' local dynamics being either discrete or continuous. Here our main result is that a certain number of additional links, with the relative position in the network being crucial, can be beneficial to ensure stable synchronization.

  10. Tweaking synchronization by connectivity modifications.

    PubMed

    Schultz, Paul; Peron, Thomas; Eroglu, Deniz; Stemler, Thomas; Ramírez Ávila, Gonzalo Marcelo; Rodrigues, Francisco A; Kurths, Jürgen

    2016-06-01

    Natural and man-made networks often possess locally treelike substructures. Taking such tree networks as our starting point, we show how the addition of links changes the synchronization properties of the network. We focus on two different methods of link addition. The first method adds single links that create cycles of a well-defined length. Following a topological approach, we introduce cycles of varying length and analyze how this feature, as well as the position in the network, alters the synchronous behavior. We show that in particular short cycles can lead to a maximum change of the Laplacian's eigenvalue spectrum, dictating the synchronization properties of such networks. The second method connects a certain proportion of the initially unconnected nodes. We simulate dynamical systems on these network topologies, with the nodes' local dynamics being either discrete or continuous. Here our main result is that a certain number of additional links, with the relative position in the network being crucial, can be beneficial to ensure stable synchronization.

  11. Tweaking synchronization by connectivity modifications.

    PubMed

    Schultz, Paul; Peron, Thomas; Eroglu, Deniz; Stemler, Thomas; Ramírez Ávila, Gonzalo Marcelo; Rodrigues, Francisco A; Kurths, Jürgen

    2016-06-01

    Natural and man-made networks often possess locally treelike substructures. Taking such tree networks as our starting point, we show how the addition of links changes the synchronization properties of the network. We focus on two different methods of link addition. The first method adds single links that create cycles of a well-defined length. Following a topological approach, we introduce cycles of varying length and analyze how this feature, as well as the position in the network, alters the synchronous behavior. We show that in particular short cycles can lead to a maximum change of the Laplacian's eigenvalue spectrum, dictating the synchronization properties of such networks. The second method connects a certain proportion of the initially unconnected nodes. We simulate dynamical systems on these network topologies, with the nodes' local dynamics being either discrete or continuous. Here our main result is that a certain number of additional links, with the relative position in the network being crucial, can be beneficial to ensure stable synchronization. PMID:27415259

  12. The solar-coffee connection

    SciTech Connect

    Wright, G.

    2000-04-01

    Coffee connoisseurs, when they quaff a cup of coffee or enjoy a jug of joe, don't generally consider the costs to the environment of their favorite beverage. But the fact is that traditional coffee production is hard on the environment, exacting a toll on the native forests and waterways of Central America and on the migratory birds of the western hemisphere. Coffee growing is the second greatest cause of rainforest destruction after cattle ranching, because a lot of trees are cut down to dry the freshly-picked coffee crop. But espresso-sipping environmentalists and an eco-conscious Joe Public can take comfort in a promising new connection between solar energy and rainforest-friendly coffee--solar-dried coffee. And they can take pleasure in it too, because solar-dried coffee, according to virtually everyone who tries it, is the best-tasting coffee made. Considering that coffee is the second most-traded commodity next to oil, and the second most popular beverage in the world next to water, consumed by billions of people, any new process that reduces the environmental damage occasioned by coffee-growing and processing is significant.

  13. Cross-Connections of Chemistry

    NASA Astrophysics Data System (ADS)

    Mason, Diana S.

    2002-02-01

    We are in desperate need of qualified chemistry teachers. Are the teachers who have biology, physics, or some psychology degrees qualified to teach chemistry? Have they taken enough chemistry to be prepared to teach outside their degree field? If remediation is necessary, what courses should be required? Attracting pre-service science teachers to the study of pure chemistry is not an easy task when more attractive course offerings are available. Maybe we should concentrate on cross-training in-service teachers by providing appropriate graduate courses to encourage them and bring them into the family. Many teachers with degrees outside the traditional discipline of chemistry have adequate backgrounds in the applications of chemistry. Requiring hours of undergraduate education before they enter the hallowed halls of the chemistry building as graduate students only serves to discourage a large segment of in-service teachers who wish to broaden their perspective. The National Science Education Standards make a compelling argument for connecting and integrating science courses for practicing teachers (3). We are at the crossroads. At a time when we so desperately need qualified chemistry teachers, shouldn't we be more open in our graduate teaching programs, inviting those with degrees in other disciplines to start on a graduate degree without insisting on undergraduate or survey coursework first? Many potential chemical education graduate students have a background in chemistry--it is just known by another name.

  14. Multiple Proof Approaches and Mathematical Connections

    ERIC Educational Resources Information Center

    Jiang, Zhonghong; O'Brien, George E.

    2012-01-01

    One of the most rewarding accomplishments of working with preservice secondary school mathematics teachers is helping them develop conceptually connected knowledge and see mathematics as an integrated whole rather than isolated pieces. To help students see and use the connections among various mathematical topics, the authors have paid close…

  15. Quick-Connect Heavy-Duty Fastener

    NASA Technical Reports Server (NTRS)

    Moore, D. M.

    1986-01-01

    Attaching device combines fast connection and disconnection with high strength. T-shaped stud engages groove in receptacle after one-quarter turn. Further turning tightens nut on receptacle. Like quarter-turn attaching devices, connected and disconnected quickly. Like threaded devices, adjusted to desired preload, withstand high loads, and accommodate wide range of grip lengths.

  16. Check & Connect. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2006

    2006-01-01

    "Check & Connect" is a dropout prevention strategy that relies on close monitoring of school performance, as well as mentoring, case management, and other supports. The What Works Clearinghouse (WWC) reviewed six studies on "Check & Connect" that were designed to assess the program's effectiveness. Four of these studies…

  17. Lewis and Clark--Indiana Connections.

    ERIC Educational Resources Information Center

    Bennett, Pamela J., Ed.

    2003-01-01

    The state of Indiana has an important, recognized connection to the Lewis and Clark Expedition. That connection is reinforced with a National Signature Event in Clarksville (Indiana) during October 2003. Until the expedition party left its winter camp in May 1804, it remained in Indiana Territory, governed from Vincennes (Indiana) by William Henry…

  18. Connected Education: The First Two Years.

    ERIC Educational Resources Information Center

    Levinson, Paul

    1986-01-01

    This paper describes Connect Ed, a program offering graduate and undergraduate courses for credit via computer conferencing. It is noted that these courses are offered in conjunction with the Masters Degree in Media Studies at the New School for Social Research and the Polytechnic Institute, both in New York City. A progress report on Connect Ed's…

  19. Making Connections between Research and Practice

    ERIC Educational Resources Information Center

    Porter, Andrew; McMaken, Jennifer

    2009-01-01

    Strengthening connections between research and practice is an important goal in education. Making the connection has both a supply side and a demand side but the demand is often ignored in education. The authors offer six hypotheses about why this situation occurs.

  20. Making the Chromosome-Gene-Protein Connection.

    ERIC Educational Resources Information Center

    Mulvihill, Charlotte

    1996-01-01

    Presents an exercise that demonstrates the chromosome-gene-protein connection using sickle-cell anemia, a genetic disease with a well-characterized molecular basis. Involves connecting changes in DNA to protein outcomes and tying them into the next generation by meiosis and gamete formation with genetic crosses. Motivates students to integrate…

  1. "Only Connect"? Complexities in International Student Communication

    ERIC Educational Resources Information Center

    Bell, Frances; Zaitseva, Elena

    2005-01-01

    This article explores the potential and limitations of international educational collaboration using the concept of "connection", a term with different meanings that are sometimes conflated to produce unrealistic expectations of computer-mediated communication (CMC). The authors explore the use on the Internet of the "only connect" quote from…

  2. Connecting Representations: Using Predict, Check, Explain

    ERIC Educational Resources Information Center

    Roy, George J.; Fueyo, Vivian; Vahey, Philip; Knudsen, Jennifer; Rafanan, Ken; Lara-Meloy, Teresa

    2016-01-01

    Although educators agree that making connections with the real world, as advocated by "Principles to Actions: Ensuring Mathematical Success for All" (NCTM 2014), is important, making such connections while addressing important mathematics is elusive. The authors have found that math content coupled with the instructional strategy of…

  3. Water Treatment Technology - Cross-Connections.

    ERIC Educational Resources Information Center

    Ross-Harrington, Melinda; Kincaid, G. David

    One of twelve water treatment technology units, this student manual on cross connections provides instructional materials for two competencies. (The twelve units are designed for a continuing education training course for public water supply operators.) The competencies focus on cross connections terminology and control devices. For each…

  4. Movement and Learning: A Valuable Connection

    ERIC Educational Resources Information Center

    Stevens-Smith, Deborah

    2004-01-01

    In this article, the author discusses the relatedness between movement and learning for students. The process of learning involves basic nerve cells that transmit information and create numerous neural connections essential to learning. One way to increase learning is to encourage creation of more synaptic connections in the brain through…

  5. Making Connections in the Undergraduate Laboratory.

    ERIC Educational Resources Information Center

    Poole, Bobbie J.; Kidder, Stanley Q.

    1996-01-01

    Describes a strategy used in a meteorology course to increase its relevance to students' lives. Involves combining the lecture and laboratory portions of the course and including a Connections section in the lab report in which students comment on the connections they saw between the coursework, the laboratory exercises, and their own experience.…

  6. A Random Walk: Stumbling across Connections

    ERIC Educational Resources Information Center

    Wasserman, Nicholas H.

    2015-01-01

    Finding and designing tasks that allow for students to make connections among mathematical ideas is important for mathematics educators. One such task, which affords students the opportunity to make connections and engage with significant mathematical ideas through a variety of problem-solving approaches, is described in this article. Three…

  7. Connecting Functions in Geometry and Algebra

    ERIC Educational Resources Information Center

    Steketee, Scott; Scher, Daniel

    2016-01-01

    One goal of a mathematics education is that students make significant connections among different branches of mathematics. Connections--such as those between arithmetic and algebra, between two-dimensional and three-dimensional geometry, between compass-and-straight-edge constructions and transformations, and between calculus and analytic…

  8. Building Cohesion in Positively Connected Exchange Networks

    ERIC Educational Resources Information Center

    Schaefer, David R.; Kornienko, Olga

    2009-01-01

    This research investigates the process through which individuals build cohesive relationships in positively connected exchange relations. Positive connections exist any time exchange in one relation must precede exchange in another. Such situations arise through gatekeeping, in generalized exchange contexts, and when resources diffuse across a…

  9. Elders' Lifelong Connection with the Natural Environment

    ERIC Educational Resources Information Center

    Carman, Jack

    2011-01-01

    Our interaction with nature does not end just because we age. People have a lifelong connection with the outdoor environment in varying degrees. For some, this participation may be subtle by simply watching others interact with the outdoor environment. For others, there is a deeper connection with nature through gardening, birding, exercise,…

  10. Making Connections: The Home Front Fair

    ERIC Educational Resources Information Center

    Roessing, Lesley

    2007-01-01

    Much of what students learn never appears to connect to their lives. They learn facts, they study events, and they read stories of others. Teachers need to help students make these associations, and sometimes that means expanding the curriculum. To help her language arts students make connections between their lives and the realities of life…

  11. An assessment of the connection machine

    NASA Technical Reports Server (NTRS)

    Schreiber, Robert

    1990-01-01

    The CM-2 is an example of a connection machine. The strengths and problems of this implementation are considered as well as important issues in the architecture and programming environment of connection machines in general. These are contrasted to the same issues in Multiple Instruction/Multiple Data (MIMD) microprocessors and multicomputers.

  12. Making Connections--The Big Picture.

    ERIC Educational Resources Information Center

    Halyard, Rebecca A.

    1994-01-01

    Helping students to make essential connections of science content is often difficult, yet necessary to ensure a true understanding of science. A teacher offers insights on how pyruvic acid can be used to help students make connections in chemistry and biology. (ZWH)

  13. Reflections on Connecting through Outdoor Adventure

    ERIC Educational Resources Information Center

    Ritchie, Stephen; Brinkman, Danielle; Wabano, Mary Jo; Young, Nancy

    2011-01-01

    Connecting through outdoor adventure is a process that may or may not seem obvious. The word "connecting" resonates with a powerful and extensive implied meaning that the authors feel compelled to share. A recent collaborative research project between leaders from the Wikwemikong Unceded Indian Reserve and researchers from Laurentian University…

  14. Science and Mathematics--A Natural Connection

    ERIC Educational Resources Information Center

    Park Rogers, Meredith A.; Volkmann, Mark J.; Abell, Sandra K.

    2007-01-01

    Connections between science and mathematics seem natural. First, mathematics can be used in science to organize and analyze data in tables and graphs. Second, mathematics can help represent scientific phenomena and understand scientific concepts. Student learning should benefit when teachers make the connections between science and mathematics…

  15. School-Community Connections: A Literature Review.

    ERIC Educational Resources Information Center

    Keyes, Marian C.; Gregg, Soleil

    This literature review surveys the varieties and purposes of connections between schools and communities, from home-school relationships to schools as social service centers and communities as school curricula. It explores the benefits of school-community connections to students, communities, and schools. It describes the processes by which…

  16. The Matrix Connection: Fibonacci and Inductive Proof

    ERIC Educational Resources Information Center

    Veenstra, Tamara B.; Miller, Catherine M.

    2006-01-01

    This article presents several activities (some involving graphing calculators) designed to guide students to discover several interesting properties of Fibonacci numbers. Then, we explore interesting connections between Fibonacci numbers and matrices; using this connection and induction we prove divisibility properties of Fibonacci numbers.

  17. 24 CFR 3285.602 - Utility connections.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Utility connections. 3285.602 Section 3285.602 Housing and Urban Development Regulations Relating to Housing and Urban Development... Systems § 3285.602 Utility connections. Refer to § 3285.904 for considerations for utility...

  18. Physical Science Connected Classrooms: Case Studies

    ERIC Educational Resources Information Center

    Irving, Karen; Sanalan, Vehbi; Shirley, Melissa

    2009-01-01

    Case-study descriptions of secondary and middle school classrooms in diverse contexts provide examples of how teachers implement connected classroom technology to facilitate formative assessment in science instruction. Connected classroom technology refers to a networked system of handheld devices designed for classroom use. Teachers were…

  19. Connect the Book. George Washington's Teeth

    ERIC Educational Resources Information Center

    Brodie, Carolyn S.

    2005-01-01

    February celebrates both National Children's Dental Health Month and President's Day (February 21), so this month's "Connect the Book" column features a book with connections to both events. George Washington, the first President of the United States (1789-1797) and known as the "Father of Our Country," had a serious dental health problem that…

  20. Infinitesimal affine automorphisms of symplectic connections

    NASA Astrophysics Data System (ADS)

    Fox, Daniel J. F.

    2016-08-01

    Conditions are given under which an infinitesimal automorphism of a torsion-free connection preserving a symplectic form is necessarily a symplectic vector field. An example is given of a compact symplectic nilmanifold admitting a flat symplectic connection and an infinitesimal automorphism that is not symplectic.

  1. Directional connectivity in hydrology and ecology.

    PubMed

    Larsen, Laurel G; Choi, Jungyill; Nungesser, Martha K; Harvey, Judson W

    2012-12-01

    Quantifying hydrologic and ecological connectivity has contributed to understanding transport and dispersal processes and assessing ecosystem degradation or restoration potential. However, there has been little synthesis across disciplines. The growing field of ecohydrology and recent recognition that loss of hydrologic connectivity is leading to a global decline in biodiversity underscore the need for a unified connectivity concept. One outstanding need is a way to quantify directional connectivity that is consistent, robust to variations in sampling, and transferable across scales or environmental settings. Understanding connectivity in a particular direction (e.g., streamwise, along or across gradient, between sources and sinks, along cardinal directions) provides critical information for predicting contaminant transport, planning conservation corridor design, and understanding how landscapes or hydroscapes respond to directional forces like wind or water flow. Here we synthesize progress on quantifying connectivity and develop a new strategy for evaluating directional connectivity that benefits from use of graph theory in ecology and percolation theory in hydrology. The directional connectivity index (DCI) is a graph-theory based, multiscale metric that is generalizable to a range of different structural and functional connectivity applications. It exhibits minimal sensitivity to image rotation or resolution within a given range and responds intuitively to progressive, unidirectional change. Further, it is linearly related to the integral connectivity scale length--a metric common in hydrology that correlates well with actual fluxes--but is less computationally challenging and more readily comparable across different landscapes. Connectivity-orientation curves (i.e., directional connectivity computed over a range of headings) provide a quantitative, information-dense representation of environmental structure that can be used for comparison or detection of

  2. Connectivity: What is it good for?

    NASA Astrophysics Data System (ADS)

    Zimmermann, A.; Zimmermann, B.; Elsenbeer, H.

    2012-04-01

    In extensive areas of the Panama Canal watershed, large and frequent tropical storms hit clay-rich soils that feature a low saturated hydraulic conductivity at shallow depth. As a consequence, surface runoff occurs frequently, and extremely flashy catchment responses are common. Previous studies showed that in undisturbed forests of this region, overland flow tends to concentrate in flowlines which extend the channel network and therefore provide hydrological connectivity between hillslopes and streams. In this contribution we present our latest research which aims at explaining the development and dynamics of overland-flow connectivity and its impact on catchment runoff and suspended-sediment export. In an undisturbed headwater catchment we monitored on an event basis overland-flow occurrence in all flowlines and measured discharge and suspended-sediment concentration in several flowlines and at the catchment outlet. Under certain meteorological conditions all flowlines are connected to the channel network throughout their entire lengths. Because some flowlines originate near the catchment divide, extensive parts of the catchment are then hydrologically connected. It was for these high-connectivity situations that we measured the largest storm flows and sediment yields at the catchment outlet. Yet, both runoff volume and sediment yield varied up to an order of magnitude during the high-connectivity stage. This is because our connectivity data comprise just one feature of connectivity; that is, whether flow is connected or not. Hydrologic connectivity (at the soil surface), however, also entails other critical aspects such as the duration of a particular connectivity stage. Although promising, the effort required to monitor these aspects of connectivity is substantial. Moreover, it is not clear how such specific information can be transferred to other catchments. Therefore, besides more detailed investigations we advocate applying the established link between

  3. Directional connectivity in hydrology and ecology

    USGS Publications Warehouse

    Larsen, Laurel G.; Choi, Jungyill; Nungesser, Martha K.; Harvey, Judson W.

    2012-01-01

    Quantifying hydrologic and ecological connectivity has contributed to understanding transport and dispersal processes and assessing ecosystem degradation or restoration potential. However, there has been little synthesis across disciplines. The growing field of ecohydrology and recent recognition that loss of hydrologic connectivity is leading to a global decline in biodiversity underscore the need for a unified connectivity concept. One outstanding need is a way to quantify directional connectivity that is consistent, robust to variations in sampling, and transferable across scales or environmental settings. Understanding connectivity in a particular direction (e.g., streamwise, along or across gradient, between sources and sinks, along cardinal directions) provides critical information for predicting contaminant transport, planning conservation corridor design, and understanding how landscapes or hydroscapes respond to directional forces like wind or water flow. Here we synthesize progress on quantifying connectivity and develop a new strategy for evaluating directional connectivity that benefits from use of graph theory in ecology and percolation theory in hydrology. The directional connectivity index (DCI) is a graph-theory based, multiscale metric that is generalizable to a range of different structural and functional connectivity applications. It exhibits minimal sensitivity to image rotation or resolution within a given range and responds intuitively to progressive, unidirectional change. Further, it is linearly related to the integral connectivity scale length—a metric common in hydrology that correlates well with actual fluxes—but is less computationally challenging and more readily comparable across different landscapes. Connectivity-orientation curves (i.e., directional connectivity computed over a range of headings) provide a quantitative, information-dense representation of environmental structure that can be used for comparison or detection of

  4. The sum-connectivity index--an additive variant of the Randic connectivity index.

    PubMed

    Lučić, Bono; Sović, Ivan; Batista, Jadranko; Skala, Karolj; Plavšić, Dejan; Vikić-Topić, Drazen; Bešlo, Drago; Nikolić, Sonja; Trinajstić, Nenad

    2013-06-01

    This review discusses structure-property modeling applications of a novel variant of the Randic connectivity index that is called the sum-connectivity index. We compare published one-descriptor quantitative structure-property relationship (QSPR) models obtained with the new sum-connectivity index and with the Randic connectivity index, called here the product-connectivity index. Additionally, the efficiency of both variants of connectivity indices in QSPR modeling is tested on five datasets of alkanes and two datasets of polycyclic hydrocarbons. Several physicochemical properties of alkanes (i.e. boiling and melting points, retention index, molar volume, molar refraction, heat of vaporization, standard Gibbs energy of formation, critical temperature, critical pressure, surface tension, density) and π- electronic energies of two sets of polycyclic hydrocarbons were correlated with the product- and sum-connectivity indices. A comparison of these QSPR models shows that both variants of connectivity indices are equivalent, and only slightly (but not significantly) better results are obtained with the sum-connectivity index. Inter-correlations between the product- and sum-connectivity indices are mostly linear with a slope very close to 1.0 for alkanes, and with a slope more different from 1.0 (0.88) for polycyclic compounds. The comparative analysis presented here supports the use of the sumconnectivity index in QSPR/QSAR studies together with the product-connectivity index. Further studies on larger and more heterogeneous datasets should test the sum-connectivity index in QSPR/QSAR models.

  5. The sum-connectivity index--an additive variant of the Randic connectivity index.

    PubMed

    Lučić, Bono; Sović, Ivan; Batista, Jadranko; Skala, Karolj; Plavšić, Dejan; Vikić-Topić, Drazen; Bešlo, Drago; Nikolić, Sonja; Trinajstić, Nenad

    2013-06-01

    This review discusses structure-property modeling applications of a novel variant of the Randic connectivity index that is called the sum-connectivity index. We compare published one-descriptor quantitative structure-property relationship (QSPR) models obtained with the new sum-connectivity index and with the Randic connectivity index, called here the product-connectivity index. Additionally, the efficiency of both variants of connectivity indices in QSPR modeling is tested on five datasets of alkanes and two datasets of polycyclic hydrocarbons. Several physicochemical properties of alkanes (i.e. boiling and melting points, retention index, molar volume, molar refraction, heat of vaporization, standard Gibbs energy of formation, critical temperature, critical pressure, surface tension, density) and π- electronic energies of two sets of polycyclic hydrocarbons were correlated with the product- and sum-connectivity indices. A comparison of these QSPR models shows that both variants of connectivity indices are equivalent, and only slightly (but not significantly) better results are obtained with the sum-connectivity index. Inter-correlations between the product- and sum-connectivity indices are mostly linear with a slope very close to 1.0 for alkanes, and with a slope more different from 1.0 (0.88) for polycyclic compounds. The comparative analysis presented here supports the use of the sumconnectivity index in QSPR/QSAR studies together with the product-connectivity index. Further studies on larger and more heterogeneous datasets should test the sum-connectivity index in QSPR/QSAR models. PMID:23700992

  6. The SOHO-Stellar Connection

    NASA Technical Reports Server (NTRS)

    Ayres, Thomas R.

    1999-01-01

    I discusses practical aspects of the so-called "solar-stellar" connection; namely, the fundamental principles, the tools at the disposal of the stellar astronomer, and a few recent examples of the connection in action. I provide an overall evolutionary context for coronal activity, calling attention to the very different circumstances of low mass main sequence stars like the Sun, which are active mainly early in their lives; compared with more massive stars, whose coronally active phase occurs near the end of their lives, during their brief incursion into the cool half of the Hertzsprung-Russell diagram as yellow and then red giants. On the instrumental slide, I concentrate primarily on spectroscopy, in the ultraviolet and X-ray bands where coronae leave their most obvious signatures. I present an early glimpse of the type of moderate resolution spectra we can expect from the recently launched Chandra observatory, and contemporaneous HST STIS high-resolution UV measurements of the CXO calibration star Capella (alpha Aur; G8 III + G1 III). I compare STIS spectra of solar-type dwarfs-zeta Dor (F7 V), an active coronal source; and alpha Cen A (G2 V), a near twin of the Sun-to a trace obtained with the SOHO SUMER imaging UV spectrometer. I also compare STIS line profiles of the active coronal dwarf to the corresponding features in the mixed-activity "hybrid-chromosphere" bright giant alpha TrA (K2 II) and the archetype "noncoronal" red giant Arcturus (alpha Boo; K2 III). The latter shows dramatic evidence for a "cool absorber" in its outer atmosphere that is extinguishing the "hot lines" (like Si IV lambda1393 and N V lambda1238) below about 1500 A, probably through absorption in the Si I lambda1525 and C I lambda1240 photoionization continua. The disappearance of coronae across the "Linsky-Haisch" dividing line near K1 III thus apparently is promoted by a dramatic overturning in the outer atmospheric structure, namely the coronae of the red giants seem to lie beneath

  7. Pressure-balanced stab connection

    SciTech Connect

    Best, M.J.A.; Jones, R.H.; Hynes, J.H.; Pond, R.J.; Gordon, C.R.

    1987-09-22

    This patent describes an apparatus for sealingly connecting a flow bore of a wellhead to a flowline. It consists of: a stab member including a stab body. The stab body has a stab body bore. One end of the stab body bore exiting from the stab body and being in fluid communication with the flow bore and the other end of the stab body bore exiting from a side of the stab body through a stab body side port; a stab receptacle mounted on the wellhead and having a stab receiving bore for receiving the stab body; the stab receptacle having a receptacle flow bore. One end of the receptacle flow bore being in fluid communication with the stab receiving bore and the other end of the receptacle flow bore exiting the stab receptacle and being in fluid communication with the flowline; means for establishing fluid communication between the stab body side port and the one end of the receptacle flow bore when the stab body is received within the stab receiving bore. It includes means disposed on the stab member for orienting the stab member with respect to the Christmas tree for ensuring the alignment of the stab body side port with the one end of the receptable flow bore when the stab body is received within the stab receiving bore; and first and second sealing means disposed on the stab body above and below the stab body side port, respectively, for sealing engagement with the walls of the stab receiving bore above and below the one end of the receptable flow bore for establishing a non-blow-apart, fluid pressure sealed flow passage between the stab body bore of the stab member and the receptacle flow bore of the stab receptacle when the stab body is landed within the stab receiving bore.

  8. Brain Connectivity Analysis: A Short Survey

    PubMed Central

    Lang, E. W.; Tomé, A. M.; Keck, I. R.; Górriz-Sáez, J. M.; Puntonet, C. G.

    2012-01-01

    This short survey the reviews recent literature on brain connectivity studies. It encompasses all forms of static and dynamic connectivity whether anatomical, functional, or effective. The last decade has seen an ever increasing number of studies devoted to deduce functional or effective connectivity, mostly from functional neuroimaging experiments. Resting state conditions have become a dominant experimental paradigm, and a number of resting state networks, among them the prominent default mode network, have been identified. Graphical models represent a convenient vehicle to formalize experimental findings and to closely and quantitatively characterize the various networks identified. Underlying these abstract concepts are anatomical networks, the so-called connectome, which can be investigated by functional imaging techniques as well. Future studies have to bridge the gap between anatomical neuronal connections and related functional or effective connectivities. PMID:23097663

  9. Connectiveness and civility in online learning.

    PubMed

    Rieck, Susan; Crouch, Laura

    2007-11-01

    As the classroom shifts from teacher-centered to learner-centered and from face-to-face to online, nursing faculty members are challenged to promote a sense of connectiveness and social interaction. Making connectiveness more elusive is the perception of rude, impolite, or unkind communication. The purpose of this descriptive-exploratory study was to examine perceptions of connectiveness and civility in online nursing courses. Ninety-six students in four nursing programs participated in the study. Strategies that promote connectiveness with peers are in-person activities whenever possible and discussion assignments that include social activities. Timely feedback when responding to questions and prompt grading are important for student-to-instructor connectiveness. Thirty-five percent of the students encountered rude or unkind communication with peers, and 60% reported incivility from instructors. Their suggestions for effective handling of rude communication included addressing the behavior privately, giving guidance about netiquette, and defining what constitutes rude behavior. PMID:17765016

  10. The Genetics of Soft Connective Tissue Disorders.

    PubMed

    Vanakker, Olivier; Callewaert, Bert; Malfait, Fransiska; Coucke, Paul

    2015-01-01

    Over the last few years, the field of hereditary connective tissue disorders has changed tremendously. This review highlights exciting insights into three prototypic disorders affecting the soft connective tissue: Ehlers-Danlos syndrome, pseudoxanthoma elasticum, and cutis laxa. For each of these disorders, the identification and characterization of several novel but related conditions or subtypes have widened the phenotypic spectrum. In parallel, the vast underlying molecular network connecting these phenotypes is progressively being uncovered. Identification and characterization (both clinical and molecular) of new phenotypes within the connective tissue disorder spectrum are often key to further unraveling the pathways involved in connective tissue biology and delineating the clinical spectrum and pathophysiology of the disorders. Although difficult challenges remain, recent findings have expanded our pathophysiological understanding and may lead to targeted therapies in the near future. PMID:26002060

  11. Connected Knowledge in Science and Mathematics Education

    NASA Astrophysics Data System (ADS)

    Zohar, Anat

    2006-10-01

    While the traditional meaning of connected knowledge is valuable in some school subjects, it does not address the main activities of knowledge acquisition in subjects such as physics and mathematics. The goal of this article is to analyze the relationships between the concepts “learning for understanding” and “connected knowledge”, a central theme in feminist epistemology. In learning for understanding, the learner forms multiple, intricate connections among the concepts she is studying in school, between school concepts and her everyday concepts, and between school concepts and their wider context. Viewing connected knowledge as tightly related to understanding has several important implications. It brings connected knowledge into the central learning activities that take place in school science and mathematics, and gives it a high status. It contributes to our understanding of gender-related patterns in thinking; and it may form a unifying theoretical framework for many studies and projects in the field of gender fair education.

  12. Resting-State Functional Connectivity in Late-Life Depression: Higher Global Connectivity and More Long Distance Connections

    PubMed Central

    Bohr, Iwo Jerzy; Kenny, Eva; Blamire, Andrew; O’Brien, John T.; Thomas, Alan J.; Richardson, Jonathan; Kaiser, Marcus

    2013-01-01

    Functional magnetic resonance imaging recordings in the resting-state (RS) from the human brain are characterized by spontaneous low-frequency fluctuations in the blood oxygenation level dependent signal that reveal functional connectivity (FC) via their spatial synchronicity. This RS study applied network analysis to compare FC between late-life depression (LLD) patients and control subjects. Raw cross-correlation matrices (CM) for LLD were characterized by higher FC. We analyzed the small-world (SW) and modular organization of these networks consisting of 110 nodes each as well as the connectivity patterns of individual nodes of the basal ganglia. Topological network measures showed no significant differences between groups. The composition of top hubs was similar between LLD and control subjects, however in the LLD group posterior medial-parietal regions were more highly connected compared to controls. In LLD, a number of brain regions showed connections with more distant neighbors leading to an increase of the average Euclidean distance between connected regions compared to controls. In addition, right caudate nucleus connectivity was more diffuse in LLD. In summary, LLD was associated with overall increased FC strength and changes in the average distance between connected nodes, but did not lead to global changes in SW or modular organization. PMID:23316175

  13. Road Weather and Connected Vehicles

    NASA Astrophysics Data System (ADS)

    Pisano, P.; Boyce, B. C.

    2015-12-01

    On average, there are over 5.8 M vehicle crashes each year of which 23% are weather-related. Weather-related crashes are defined as those crashes that occur in adverse weather or on slick pavement. The vast majority of weather-related crashes happen on wet pavement (74%) and during rainfall (46%). Connected vehicle technologies hold the promise to transform road-weather management by providing improved road weather data in real time with greater temporal and geographic accuracy. This will dramatically expand the amount of data that can be used to assess, forecast, and address the impacts that weather has on roads, vehicles, and travelers. The use of vehicle-based measurements of the road and surrounding atmosphere with other, more traditional weather data sources, and create road and atmospheric hazard products for a variety of users. The broad availability of road weather data from mobile sources will vastly improve the ability to detect and forecast weather and road conditions, and will provide the capability to manage road-weather response on specific roadway links. The RWMP is currently demonstrating how weather, road conditions, and related vehicle data can be used for decision making through an innovative Integrated Mobile Observations project. FHWA is partnering with 3 DOTs (MN, MI, & NV) to pilot these applications. One is a mobile alerts application called the Motorists Advisories and Warnings (MAW) and a maintenance decision support application. These applications blend traditional weather information (e.g., radar, surface stations) with mobile vehicle data (e.g., temperature, brake status, wiper status) to determine current weather conditions. These weather conditions, and other road-travel-relevant information, are provided to users via web and phone applications. The MAW provides nowcasts and short-term forecasts out to 24 hours while the EMDSS application can provide forecasts up to 72 hours in advance. The three DOTs have placed readers and external

  14. Detecting Functional Connectivity During Audiovisual Integration with MEG: A Comparison of Connectivity Metrics.

    PubMed

    Ard, Tyler; Carver, Frederick W; Holroyd, Tom; Horwitz, Barry; Coppola, Richard

    2015-08-01

    In typical magnetoencephalography and/or electroencephalography functional connectivity analysis, researchers select one of several methods that measure a relationship between regions to determine connectivity, such as coherence, power correlations, and others. However, it is largely unknown if some are more suited than others for various types of investigations. In this study, the authors investigate seven connectivity metrics to evaluate which, if any, are sensitive to audiovisual integration by contrasting connectivity when tracking an audiovisual object versus connectivity when tracking a visual object uncorrelated with the auditory stimulus. The authors are able to assess the metrics' performances at detecting audiovisual integration by investigating connectivity between auditory and visual areas. Critically, the authors perform their investigation on a whole-cortex all-to-all mapping, avoiding confounds introduced in seed selection. The authors find that amplitude-based connectivity measures in the beta band detect strong connections between visual and auditory areas during audiovisual integration, specifically between V4/V5 and auditory cortices in the right hemisphere. Conversely, phase-based connectivity measures in the beta band as well as phase and power measures in alpha, gamma, and theta do not show connectivity between audiovisual areas. The authors postulate that while beta power correlations detect audiovisual integration in the current experimental context, it may not always be the best measure to detect connectivity. Instead, it is likely that the brain utilizes a variety of mechanisms in neuronal communication that may produce differential types of temporal relationships.

  15. Detecting Functional Connectivity During Audiovisual Integration with MEG: A Comparison of Connectivity Metrics

    PubMed Central

    Carver, Frederick W.; Holroyd, Tom; Horwitz, Barry; Coppola, Richard

    2015-01-01

    Abstract In typical magnetoencephalography and/or electroencephalography functional connectivity analysis, researchers select one of several methods that measure a relationship between regions to determine connectivity, such as coherence, power correlations, and others. However, it is largely unknown if some are more suited than others for various types of investigations. In this study, the authors investigate seven connectivity metrics to evaluate which, if any, are sensitive to audiovisual integration by contrasting connectivity when tracking an audiovisual object versus connectivity when tracking a visual object uncorrelated with the auditory stimulus. The authors are able to assess the metrics' performances at detecting audiovisual integration by investigating connectivity between auditory and visual areas. Critically, the authors perform their investigation on a whole-cortex all-to-all mapping, avoiding confounds introduced in seed selection. The authors find that amplitude-based connectivity measures in the beta band detect strong connections between visual and auditory areas during audiovisual integration, specifically between V4/V5 and auditory cortices in the right hemisphere. Conversely, phase-based connectivity measures in the beta band as well as phase and power measures in alpha, gamma, and theta do not show connectivity between audiovisual areas. The authors postulate that while beta power correlations detect audiovisual integration in the current experimental context, it may not always be the best measure to detect connectivity. Instead, it is likely that the brain utilizes a variety of mechanisms in neuronal communication that may produce differential types of temporal relationships. PMID:25599264

  16. Mapping hydrologic connectivity of geographically isolated wetlands

    NASA Astrophysics Data System (ADS)

    Ameli, Ali; Creed, Irena

    2016-04-01

    Geographically isolated wetlands (GIWs) are characterized as depressional landscape features completely surrounded by uplands. These small and typically circular landscape features represent a vast majority of wetlands in various landscapes in North America (98% of all wetlands in the Prairie Pothole Region). Geographical isolation, however, does not imply the hydrological isolation. Although geospatial data (e.g., aerial photos) suggested that GIWs lack a persistent surface water connection, the groundwater connection between GIWs and navigable downstream waters can be substantial with large fluxes at the regional scales. The surface/subsurface connections among GIWs and between GIWs and navigable waters are difficult to map and quantify. This is intimately tied to the fact that an efficient incorporation of these small geometric features and characterization of the mechanisms behind these connectivities are challenging within grid-based simulators. We used a physically-based grid-free groundwater-surface water interaction and surface flow routing schemes to map and assess the watershed-scale GIWs connectivity within an extensively studied watershed at the Canadian prairie pothole region with high density of GIWs. The results showed that there is a persistent subsurface connectivity among GIWs and between GIWs and navigable waters. Surface connection was rare and only occurred during extreme events. The results of this paper have significant implications for developing scientifically grounded environmental policy for protection of GIWs within North American Prairie.

  17. Abnormal interhemispheric connectivity in male psychopathic offenders

    PubMed Central

    Hoppenbrouwers, Sylco S.; De Jesus, Danilo R.; Sun, Yinming; Stirpe, Tania; Hofman, Dennis; McMaster, Jeff; Hughes, Ginny; Daskalakis, Zafiris J.; Schutter, Dennis J.L.G.

    2014-01-01

    Background Psychopathic offenders inevitably violate interpersonal norms and frequently resort to aggressive and criminal behaviour. The affective and cognitive deficits underlying these behaviours have been linked to abnormalities in functional interhemispheric connectivity. However, direct neurophysiological evidence for dysfunctional connectivity in psychopathic offenders is lacking. Methods We used transcranial magnetic stimulation combined with electroencephalography to examine interhemispheric connectivity in the dorsolateral and motor cortex in a sample of psychopathic offenders and healthy controls. We also measured intracortical inhibition and facilitation over the left and right motor cortex to investigate the effects of local cortical processes on interhemispheric connectivity. Results We enrolled 17 psychopathic offenders and 14 controls in our study. Global abnormalities in right to left functional connectivity were observed in psychopathic offenders compared with controls. Furthermore, in contrast to controls, psychopathic offenders showed increased intracortical inhibition in the right, but not the left, hemisphere. Limitations The relatively small sample size limited the sensitivity to show that the abnormalities in interhemispheric connectivity were specifically related to the dorsolateral prefrontal cortex in psychopathic offenders. Conclusion To our knowledge, this study provides the first neurophysiological evidence for abnormal interhemispheric connectivity in psychopathic offenders and may further our understanding of the disruptive antisocial behaviour of these offenders. PMID:23937798

  18. NASA CONNECT: 'Glow with the Flow'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    'Geometry and Algebra: Glow with the Flow' is the second of five programs in the 2000-2001 NASA CONNECT series. Produced by NASA Langley Research Center's Office of Education, NASA CONNECT is an award-winning series of instructional programs designed to enhance the teaching of math, science and technology in grades 5-8. NASA CONNECT establishes teh 'connection' between the mathematics, science, and tehcnology concepts taught in the classroom and NASA research. NASA CONNECT is FREE and the programs in the series are in the public domain. Visit our web site adn register http://connect.larc.nasa.gov In 'Geometry and Algebra: Glow with the Flow', students will learn about the force of drag and how NASA engineers use models and glowing paints to see how air flows over vehicles in a wind tunnel. Students will also discover how the blended wing body(BWB), a concept super jumbo jet that resembles a flying wing, will affect air travelers of the future. Students will observe NASA engineers using geometry and algebra when they measure and design models to be tested in wind tunnels. By conducting classroom and on-line activities, students will make connections between NASA research and the mathematics, science and technology they learn in their classroom.

  19. Physiological integration of connected balsam poplar ramets.

    PubMed

    Adonsou, Kokouvi Emmanuel; DesRochers, Annie; Tremblay, Francine

    2016-07-01

    Clonal integration between ramets can be an ecological advantage of clonal plant species in environments where resources are patchily distributed. We investigated physiological integration among Populus balsamifera L. ramets under drought stress in order to demonstrate water sharing between connected ramets. Pairs of connected ramets were grown in separate pots in the greenhouse where half of ramets had the parental root connection severed and half were left intact. Drought stress was applied to one ramet, and growth, specific leaf area (SLA), net photosynthesis, stomatal conductance, leaf water potential and carbon isotopic composition (δ(13)C) were measured after an 8-week growing period. Droughted ramets connected to watered ramets were able to maintain high gas exchange activity and water potential, similar to watered ramets. Leaf water potential and SLA results showed that the root connection was more beneficial for proximal compared with distal ramets. The parental root connection also allowed droughted ramets to discriminate more against (13)C compared with severed ramets. In conclusion, this study shows compelling evidence of physiological integration of connected P. balsamifera ramets through water sharing. PMID:26843209

  20. Altered functional connectivity in persistent developmental stuttering

    PubMed Central

    Yang, Yang; Jia, Fanlu; Siok, Wai Ting; Tan, Li Hai

    2016-01-01

    Persistent developmental stuttering (PDS) is a speech disorder that impairs communication skills. Despite extensive research, the core causes of PDS are elusive. Converging evidence from task-induced neuroimaging methods has demonstrated the contributions of the basal ganglia and the cerebellum to PDS, but such task-state neuroimaging findings are often confounded by behavioral performance differences between subjects who stutter and normal controls. Here, using resting-state functional magnetic resonance imaging, we investigated functional connectivity within cerebellar-cortical and basal ganglia-thalamocortical networks in 16 adults who stutter and 18 age-matched fluent speakers. Seed-to-voxel analysis demonstrated that, compared to controls, adults who stutter showed alternations in functional connectivity of cerebellum to motor cortex as well as connectivity among different locals within cerebellum. Additionally, we found that functional connectivity within cerebellar circuits was significantly correlated with severity of stuttering. The alternations of functional connectivity within basal ganglia-thalamocortical networks were identified as the reduced connectivity of the putamen to the superior temporal gyrus and inferior parietal lobules in adults who stutter. The abnormalities of resting state functional connectivity are assumed to affect language planning and motor execution critical for speaking fluently. Our findings may yield neurobiological cues to the biomarkers of PDS. PMID:26743821

  1. Altered functional connectivity in persistent developmental stuttering.

    PubMed

    Yang, Yang; Jia, Fanlu; Siok, Wai Ting; Tan, Li Hai

    2016-01-01

    Persistent developmental stuttering (PDS) is a speech disorder that impairs communication skills. Despite extensive research, the core causes of PDS are elusive. Converging evidence from task-induced neuroimaging methods has demonstrated the contributions of the basal ganglia and the cerebellum to PDS, but such task-state neuroimaging findings are often confounded by behavioral performance differences between subjects who stutter and normal controls. Here, using resting-state functional magnetic resonance imaging, we investigated functional connectivity within cerebellar-cortical and basal ganglia-thalamocortical networks in 16 adults who stutter and 18 age-matched fluent speakers. Seed-to-voxel analysis demonstrated that, compared to controls, adults who stutter showed alternations in functional connectivity of cerebellum to motor cortex as well as connectivity among different locals within cerebellum. Additionally, we found that functional connectivity within cerebellar circuits was significantly correlated with severity of stuttering. The alternations of functional connectivity within basal ganglia-thalamocortical networks were identified as the reduced connectivity of the putamen to the superior temporal gyrus and inferior parietal lobules in adults who stutter. The abnormalities of resting state functional connectivity are assumed to affect language planning and motor execution critical for speaking fluently. Our findings may yield neurobiological cues to the biomarkers of PDS. PMID:26743821

  2. Physiological integration of connected balsam poplar ramets.

    PubMed

    Adonsou, Kokouvi Emmanuel; DesRochers, Annie; Tremblay, Francine

    2016-07-01

    Clonal integration between ramets can be an ecological advantage of clonal plant species in environments where resources are patchily distributed. We investigated physiological integration among Populus balsamifera L. ramets under drought stress in order to demonstrate water sharing between connected ramets. Pairs of connected ramets were grown in separate pots in the greenhouse where half of ramets had the parental root connection severed and half were left intact. Drought stress was applied to one ramet, and growth, specific leaf area (SLA), net photosynthesis, stomatal conductance, leaf water potential and carbon isotopic composition (δ(13)C) were measured after an 8-week growing period. Droughted ramets connected to watered ramets were able to maintain high gas exchange activity and water potential, similar to watered ramets. Leaf water potential and SLA results showed that the root connection was more beneficial for proximal compared with distal ramets. The parental root connection also allowed droughted ramets to discriminate more against (13)C compared with severed ramets. In conclusion, this study shows compelling evidence of physiological integration of connected P. balsamifera ramets through water sharing.

  3. Low pore connectivity in natural rock.

    PubMed

    Hu, Qinhong; Ewing, Robert P; Dultz, Stefan

    2012-05-15

    As repositories for CO(2) and radioactive waste, as oil and gas reservoirs, and as contaminated sites needing remediation, rock formations play a central role in energy and environmental management. The connectivity of the rock's porespace strongly affects fluid flow and solute transport. This work examines pore connectivity and its implications for fluid flow and chemical transport. Three experimental approaches (imbibition, tracer concentration profiles, and imaging) were used in combination with network modeling. In the imbibition results, three types of imbibition slope [log (cumulative imbibition) vs. log (imbibition time)] were found: the classical 0.5, plus 0.26, and 0.26 transitioning to 0.5. The imbibition slope of 0.26 seen in Indiana sandstone, metagraywacke, and Barnett shale indicates low pore connectivity, in contrast to the slope of 0.5 seen in the well-connected Berea sandstone. In the tracer profile work, rocks exhibited different distances to the plateau porosity, consistent with the pore connectivity from the imbibition tests. Injection of a molten metal into connected pore spaces, followed by 2-D imaging of the solidified alloy in polished thin sections, allowed direct assessment of pore structure and lateral connection in the rock samples. Pore-scale network modeling gave results consistent with measurements, confirming pore connectivity as the underlying cause of both anomalous behaviors: imbibition slope not having the classical value of 0.5, and accessible porosity being a function of distance from the edge. A poorly connected porespace will exhibit anomalous behavior in fluid flow and chemical transport, such as a lower imbibition slope (in air-water system) and diffusion rate than expected from classical behavior.

  4. Electrical connection structure for a superconductor element

    SciTech Connect

    Lallouet, Nicolas; Maguire, James

    2010-05-04

    The invention relates to an electrical connection structure for a superconductor element cooled by a cryogenic fluid and connected to an electrical bushing, which bushing passes successively through an enclosure at an intermediate temperature between ambient temperature and the temperature of the cryogenic fluid, and an enclosure at ambient temperature, said bushing projecting outside the ambient temperature enclosure. According to the invention, said intermediate enclosure is filled at least in part with a solid material of low thermal conductivity, such as a polyurethane foam or a cellular glass foam. The invention is applicable to connecting a superconductor cable at cryogenic temperature to a device for equipment at ambient temperature.

  5. Internet topology: connectivity of IP graphs

    NASA Astrophysics Data System (ADS)

    Broido, Andre; claffy, kc

    2001-07-01

    In this paper we introduce a framework for analyzing local properties of Internet connectivity. We compare BGP and probed topology data, finding that currently probed topology data yields much denser coverage of AS-level connectivity. We describe data acquisition and construction of several IP- level graphs derived from a collection of 220 M skitter traceroutes. We find that a graph consisting of IP nodes and links contains 90.5% of its 629 K nodes in the acyclic subgraph. In particular, 55% of the IP nodes are in trees. Full bidirectional connectivity is observed for a giant component containing 8.3% of IP nodes.

  6. Transistor Effect in Improperly Connected Transistors.

    ERIC Educational Resources Information Center

    Luzader, Stephen; Sanchez-Velasco, Eduardo

    1996-01-01

    Discusses the differences between the standard representation and a realistic representation of a transistor. Presents an experiment that helps clarify the explanation of the transistor effect and shows why transistors should be connected properly. (JRH)

  7. Connecting to Develop Computational Fluency with Fractions

    ERIC Educational Resources Information Center

    Mack, Nancy K.

    2004-01-01

    Students should be encouraged to focus on a big mathematical idea and to look for connections between problems and solution strategies. This unified view suggests that the students are developing computational fluency with fractions.

  8. Partial connectivity increases cultural accumulation within groups.

    PubMed

    Derex, Maxime; Boyd, Robert

    2016-03-15

    Complex technologies used in most human societies are beyond the inventive capacities of individuals. Instead, they result from a cumulative process in which innovations are gradually added to existing cultural traits across many generations. Recent work suggests that a population's ability to develop complex technologies is positively affected by its size and connectedness. Here, we present a simple computer-based experiment that compares the accumulation of innovations by fully and partially connected groups of the same size in a complex fitness landscape. We find that the propensity to learn from successful individuals drastically reduces cultural diversity within fully connected groups. In comparison, partially connected groups produce more diverse solutions, and this diversity allows them to develop complex solutions that are never produced in fully connected groups. These results suggest that explanations of ancestral patterns of cultural complexity may need to consider levels of population fragmentation and interaction patterns between partially isolated groups. PMID:26929364

  9. 78 FR 48622 - Connect America Fund

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-09

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 54 Connect America Fund AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: In this document, the Federal Communications Commission (Commission) sua sponte reconsiders...

  10. MedlinePlus Connect: How it Works

    MedlinePlus

    ... it looks depends on how it is implemented. Web Application The Web application returns a formatted response ... for more examples of Web Application response pages. Web Service The MedlinePlus Connect REST-based Web service ...

  11. ISSUES IN LIGNIN CHEMISTRY. "THE HELSINKI CONNECTION"

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This presentation covers advances in lignin chemistry (and our Helsinki connection) on dibenzodioxocins, spirodienones, and reduced structures in lignins. It also explores the various roles in defending lignification theory (based on Freudenberg's original hypothesis) against a supposed new contende...

  12. Partial connectivity increases cultural accumulation within groups

    PubMed Central

    Boyd, Robert

    2016-01-01

    Complex technologies used in most human societies are beyond the inventive capacities of individuals. Instead, they result from a cumulative process in which innovations are gradually added to existing cultural traits across many generations. Recent work suggests that a population’s ability to develop complex technologies is positively affected by its size and connectedness. Here, we present a simple computer-based experiment that compares the accumulation of innovations by fully and partially connected groups of the same size in a complex fitness landscape. We find that the propensity to learn from successful individuals drastically reduces cultural diversity within fully connected groups. In comparison, partially connected groups produce more diverse solutions, and this diversity allows them to develop complex solutions that are never produced in fully connected groups. These results suggest that explanations of ancestral patterns of cultural complexity may need to consider levels of population fragmentation and interaction patterns between partially isolated groups. PMID:26929364

  13. Children and Place: A Natural Connection.

    ERIC Educational Resources Information Center

    Vickers, Valerie G.; Matthews, Catherine E.

    2002-01-01

    Presents seven outdoor activities on the environment and ecology to be used at the K-12 grade level. Connects students with the environment they live in and develops the critical sense of place. (Contains 26 references.) (YDS)

  14. Social connection modulates perceptions of animacy

    PubMed Central

    Powers, Katherine E.; Worsham, Andrea L.; Freeman, Jonathan B.; Wheatley, Thalia; Heatherton, Todd F.

    2014-01-01

    Human survival depends on identifying targets potentially capable of engaging in meaningful social connection. Using sets of morphed images created from animate (human) and inanimate (doll) faces, we provide converging evidence from across two studies showing that the motivation to connect with other people systematically alters the interpretation of the physical features that signal that a face is alive. Specifically, in their efforts to find and connect with other social agents, individuals who feel socially disconnected actually lower their thresholds for what it means to be alive, consistently observing animacy when fewer definitively human cues are present. From an evolutionary perspective, overattributing animacy may be an adaptive strategy, allowing people to cast a wide net when identifying possible sources of social connection and maximize their opportunities to renew social relationships. PMID:25193944

  15. Technology Tips: Making Connections Using Embedded Software.

    ERIC Educational Resources Information Center

    Groden, Claire; Pattison-Gordon, Laurie

    1995-01-01

    Discusses the use of software created for practical, real-world applications to connect mathematics to other subjects and to the world outside the classroom. Software presented includes Design Your Own Home, Bridgebuilder, Physics Explorer, Aldus Superpaint, and Sprout. (MKR)

  16. Modified mesh-connected parallel computers

    SciTech Connect

    Carlson, D.A. )

    1988-10-01

    The mesh-connected parallel computer is an important parallel processing organization that has been used in the past for the design of supercomputing systems. In this paper, the authors explore modifications of a mesh-connected parallel computer for the purpose of increasing the efficiency of executing important application programs. These modifications are made by adding one or more global mesh structures to the processing array. They show how our modifications allow asymptotic improvements in the efficiency of executing computations having low to medium interprocessor communication requirements (e.g., tree computations, prefix computations, finding the connected components of a graph). For computations with high interprocessor communication requirements such as sorting, they show that they offer no speedup. They also compare the modified mesh-connected parallel computer to other similar organizations including the pyramid, the X-tree, and the mesh-of-trees.

  17. Asthma Research: The NIH–NJRC Connection

    MedlinePlus

    ... Bar Home Current Issue Past Issues Special Section Asthma Research: The NIH–NJRC Connection Past Issues / Fall ... the many ways that NIH supports and promotes asthma research is through its strong relationship with National ...

  18. Economical solder connections to thin films

    NASA Technical Reports Server (NTRS)

    Bass, J. A.; Gaddy, E. M.

    1979-01-01

    Soldering procedure, successfully tested for attaching leads to silicon solar cells, cover-glasses, is simple, inexpensive, and very effective in forming stable connection. Procedure uses solder of indium alloyed with either silver or tin.

  19. Partial connectivity increases cultural accumulation within groups.

    PubMed

    Derex, Maxime; Boyd, Robert

    2016-03-15

    Complex technologies used in most human societies are beyond the inventive capacities of individuals. Instead, they result from a cumulative process in which innovations are gradually added to existing cultural traits across many generations. Recent work suggests that a population's ability to develop complex technologies is positively affected by its size and connectedness. Here, we present a simple computer-based experiment that compares the accumulation of innovations by fully and partially connected groups of the same size in a complex fitness landscape. We find that the propensity to learn from successful individuals drastically reduces cultural diversity within fully connected groups. In comparison, partially connected groups produce more diverse solutions, and this diversity allows them to develop complex solutions that are never produced in fully connected groups. These results suggest that explanations of ancestral patterns of cultural complexity may need to consider levels of population fragmentation and interaction patterns between partially isolated groups.

  20. Video 2 of 7: NASA Connection

    NASA Video Gallery

    This video provides the context for the lesson, including background information on recent Mars explorations showing the connection between this lesson and NASA's research. A variety of NASA scient...