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Sample records for efferent callosal connections

  1. 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.

  2. Axon Guidance Mechanisms for Establishment of Callosal Connections

    PubMed Central

    Nishikimi, Mitsuaki; Oishi, Koji; Nakajima, Kazunori

    2013-01-01

    Numerous studies have investigated the formation of interhemispheric connections which are involved in high-ordered functions of the cerebral cortex in eutherian animals, including humans. The development of callosal axons, which transfer and integrate information between the right/left hemispheres and represent the most prominent commissural system, must be strictly regulated. From the beginning of their growth, until reaching their targets in the contralateral cortex, the callosal axons are guided mainly by two environmental cues: (1) the midline structures and (2) neighboring? axons. Recent studies have shown the importance of axona guidance by such cues and the underlying molecular mechanisms. In this paper, we review these guidance mechanisms during the development of the callosal neurons. Midline populations express and secrete guidance molecules, and “pioneer” axons as well as interactions between the medial and lateral axons are also involved in the axon pathfinding of the callosal neurons. Finally, we describe callosal dysgenesis in humans and mice, that results from a disruption of these navigational mechanisms. PMID:23533817

  3. Axon guidance mechanisms for establishment of callosal connections.

    PubMed

    Nishikimi, Mitsuaki; Oishi, Koji; Nakajima, Kazunori

    2013-01-01

    Numerous studies have investigated the formation of interhemispheric connections which are involved in high-ordered functions of the cerebral cortex in eutherian animals, including humans. The development of callosal axons, which transfer and integrate information between the right/left hemispheres and represent the most prominent commissural system, must be strictly regulated. From the beginning of their growth, until reaching their targets in the contralateral cortex, the callosal axons are guided mainly by two environmental cues: (1) the midline structures and (2) neighboring? axons. Recent studies have shown the importance of axona guidance by such cues and the underlying molecular mechanisms. In this paper, we review these guidance mechanisms during the development of the callosal neurons. Midline populations express and secrete guidance molecules, and "pioneer" axons as well as interactions between the medial and lateral axons are also involved in the axon pathfinding of the callosal neurons. Finally, we describe callosal dysgenesis in humans and mice, that results from a disruption of these navigational mechanisms.

  4. The efferent and afferent connections of the supplementary motor area.

    PubMed

    Jürgens, U

    1984-05-21

    The efferent and afferent connections of the supplementary motor area (SMA) were studied in 6 squirrel monkeys using [3H]leucine and horseradish peroxidase, respectively. Efferent projections, common to all leucine-injected animals, were found to the cortical areas 9,8,44,4,2,5,7,24 and 23. Subcortically , efferents were found to the putamen, caudate nucleus, claustrum, the thalamic nuclei reticularis, ventrialis anterior, ventralis lateralis, medialis dorsalis, centralis lateralis, paracentralis , centrum medianum, parafascicularis, centralis superior lateralis, centralis inferior and lateralis posterior, the subthalamic nucleus, field H of Forel, nuel . ruber, reticular formation of midbrain, pons and medulla, the pontine gray and nucl . reticularis tegmenti pontis. Afferent connections exist with the cortical areas 9,8,6,44,4,1,2,5,7, 24 and 23, insula, fronto-parietal operculum and superior temporal sulcus. Subcortical afferent connections exist with the claustrum, nucleus of the diagonal band, nucl . basalis Meynert, basolateral amygdaloid nucleus, the thalamic nuclei ventralis anterior, ventralis lateralis, medialis dorsalis, centralis lateralis, paracentralis , centrum medianum, centralis superior lateralis, centralis inferior, lateralis posterior and pulvinaris , the posterior hypothalamus, ventral tegmental area, nucl . ruber pars parvicellularis , reticular formation of midbrain and pons, locus coeruleus and nucl . centralis superior Bechterew. The projections are discussed with respect to the possible role SMA plays in the voluntary initiation of motor actions.

  5. Dendrodendritic connections between the cochlear efferent neurons in guinea pig.

    PubMed

    Szabó, Zs; Bácskai, T; Deák, Á; Matesz, K; Veress, G; Sziklai, I

    2011-10-31

    The outer hair cells of organ of Corti are innervated by the efferent neurons of medial olivocochlear neurons (MOC) of the brainstem which modify the cochlear auditory processing and sensitivity. Most of the MOC neurons are excited by a dominant ear and only a small portion of them is excited by both ears resulting in a binaural facilitation. The functional role of the feedback system between the organ of Corti and the cochlear efferent neurons is the protection of the ear from acoustic injury. The rapid impulse propagation in the bilateral olivocochlear system is suggestive of an electrotonic interaction between the bilateral olivocochlear neurons. The morphological background of the MOC pathway is not yet completely characterized. Therefore, we have labeled the bilateral cochlear nerves with different neuronal tracers in guinea pigs. In the anesthetized animals the cochlear nerves were exposed in the basal part of the modiolus and labeled simultaneously with different retrograde fluorescent tracers. By using confocal laser scanning microscope we could detect close appositions between the dendrites of the neurons of bilateral MOC. The distance between the neighboring profiles suggested close membrane appositions without interposing glial elements. These connections might serve as one of the underlying mechanisms of the binaural facilitation mediated by the olivocochlear system. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  6. Interhemispheric Connections between the Primary Visual Cortical Areas via the Anterior Commissure in Human Callosal Agenesis

    PubMed Central

    van Meer, Nathalie; Houtman, Anne C.; Van Schuerbeek, Peter; Vanderhasselt, Tim; Milleret, Chantal; ten Tusscher, Marcel P.

    2016-01-01

    Aim: In humans, images in the median plane of the head either fall on both nasal hemi-retinas or on both temporal hemi-retinas. Interhemispheric connections allow cortical cells to have receptive fields on opposite sides. The major interhemispheric connection, the corpus callosum, is implicated in central stereopsis and disparity detection in front of the fixation plane. Yet individuals with agenesis of the corpus callosum may show normal stereopsis and disparity vergence. We set out to study a possible interhemispheric connection between primary visual cortical areas via the anterior commissure to explain this inconsistency because of the major role of these cortical areas in elaborating 3D visual perception. Methods: MRI, DTI and tractography of the brain of a 53-year old man with complete callosal agenesis and normal binocular single vision was undertaken. Tractography seed points were placed in both the right and the left V1 and V2. Nine individuals with both an intact corpus callosum and normal binocularity served as controls. Results: Interhemispheric tracts through the anterior commissure linking both V1 and V2 visual cortical areas bilaterally were indeed shown in the subject with callosal agenesis. All other individuals showed interhemispheric visual connections through the corpus callosum only. Conclusion: Callosal agenesis may result in anomalous interhemispheric connections of the primary visual areas via the anterior commissure. It is proposed here that these connections form as alternative to the normal callosal pathway and may participate in binocularity. PMID:28082873

  7. Interhemispheric Connections between the Primary Visual Cortical Areas via the Anterior Commissure in Human Callosal Agenesis.

    PubMed

    van Meer, Nathalie; Houtman, Anne C; Van Schuerbeek, Peter; Vanderhasselt, Tim; Milleret, Chantal; Ten Tusscher, Marcel P

    2016-01-01

    Aim: In humans, images in the median plane of the head either fall on both nasal hemi-retinas or on both temporal hemi-retinas. Interhemispheric connections allow cortical cells to have receptive fields on opposite sides. The major interhemispheric connection, the corpus callosum, is implicated in central stereopsis and disparity detection in front of the fixation plane. Yet individuals with agenesis of the corpus callosum may show normal stereopsis and disparity vergence. We set out to study a possible interhemispheric connection between primary visual cortical areas via the anterior commissure to explain this inconsistency because of the major role of these cortical areas in elaborating 3D visual perception. Methods: MRI, DTI and tractography of the brain of a 53-year old man with complete callosal agenesis and normal binocular single vision was undertaken. Tractography seed points were placed in both the right and the left V1 and V2. Nine individuals with both an intact corpus callosum and normal binocularity served as controls. Results: Interhemispheric tracts through the anterior commissure linking both V1 and V2 visual cortical areas bilaterally were indeed shown in the subject with callosal agenesis. All other individuals showed interhemispheric visual connections through the corpus callosum only. Conclusion: Callosal agenesis may result in anomalous interhemispheric connections of the primary visual areas via the anterior commissure. It is proposed here that these connections form as alternative to the normal callosal pathway and may participate in binocularity.

  8. Visual callosal connections: role in visual processing in health and disease.

    PubMed

    Bocci, Tommaso; Pietrasanta, Marta; Cerri, Chiara; Restani, Laura; Caleo, Matteo; Sartucci, Ferdinando

    2014-01-01

    Visual cortical areas in the two sides of the brain are interconnected by interhemispheric fibers passing through the splenium of the corpus callosum. In this review, we summarize data concerning the anatomical features of visual callosal connections, their roles in basic visual processing, and how their alterations contribute to visual deficits in different human neuropathologies. Splenial fibers represent a population of excitatory axons with varying diameters, which interconnect cortical columns with similar functional properties (i.e., same orientation selectivity) in the two hemispheres. Their branches activate simultaneously distinct iso-oriented columns in the contralateral hemisphere, thus mediating forms of stimulus-dependent interhemispheric synchronization. Callosal branches also make synapses onto GABAergic cells, resulting in an inhibitory modulation of visual processing that involves both iso-oriented and cross-oriented cortical networks. Interhemispheric inhibition appears to predominate at short latencies following callosal activation, whereas excitation becomes more robust with increasing delays. These callosal effects are dynamically adapted to the incoming visual activity, so that stimuli providing only weak afferent input are facilitated by callosal pathways, whereas strong visual input via the retinogeniculate pathway tends to be offset by transcallosal inhibition. We also review data highlighting the contribution of callosal input activity to maturation of visual function during early 'critical periods' in brain development and describe how interhemispheric transfer of visual information is rerouted in cases of callosal agenesis or following splenial damage. Finally, we provide an overview of alterations in splenium anatomy or function that may be at the basis of visual defects in several pathologic conditions.

  9. Reorganization of Visual Callosal Connections Following Alterations of Retinal Input and Brain Damage

    PubMed Central

    Restani, Laura; Caleo, Matteo

    2016-01-01

    Vision is a very important sensory modality in humans. Visual disorders are numerous and arising from diverse and complex causes. Deficits in visual function are highly disabling from a social point of view and in addition cause a considerable economic burden. For all these reasons there is an intense effort by the scientific community to gather knowledge on visual deficit mechanisms and to find possible new strategies for recovery and treatment. In this review, we focus on an important and sometimes neglected player of the visual function, the corpus callosum (CC). The CC is the major white matter structure in the brain and is involved in information processing between the two hemispheres. In particular, visual callosal connections interconnect homologous areas of visual cortices, binding together the two halves of the visual field. This interhemispheric communication plays a significant role in visual cortical output. Here, we will first review the essential literature on the physiology of the callosal connections in normal vision. The available data support the view that the callosum contributes to both excitation and inhibition to the target hemisphere, with a dynamic adaptation to the strength of the incoming visual input. Next, we will focus on data showing how callosal connections may sense visual alterations and respond to the classical paradigm for the study of visual plasticity, i.e., monocular deprivation (MD). This is a prototypical example of a model for the study of callosal plasticity in pathological conditions (e.g., strabismus and amblyopia) characterized by unbalanced input from the two eyes. We will also discuss the findings of callosal alterations in blind subjects. Noteworthy, we will discuss data showing that inter-hemispheric transfer mediates recovery of visual responsiveness following cortical damage. Finally, we will provide an overview of how callosal projections dysfunction could contribute to pathologies such as neglect and occipital

  10. Interhemispheric effective and functional cortical connectivity signatures of spina bifida are consistent with callosal anomaly.

    PubMed

    Malekpour, Sheida; Li, Zhimin; Cheung, Bing Leung Patrick; Castillo, Eduardo M; Papanicolaou, Andrew C; Kramer, Larry A; Fletcher, Jack M; Van Veen, Barry D

    2012-01-01

    The impact of the posterior callosal anomalies associated with spina bifida on interhemispheric cortical connectivity is studied using a method for estimating cortical multivariable autoregressive models from scalp magnetoencephalography data. Interhemispheric effective and functional connectivity, measured using conditional Granger causality and coherence, respectively, is determined for the anterior and posterior cortical regions in a population of five spina bifida and five control subjects during a resting eyes-closed state. The estimated connectivity is shown to be consistent over the randomly selected subsets of the data for each subject. The posterior interhemispheric effective and functional connectivity and cortical power are significantly lower in the spina bifida group, a result that is consistent with posterior callosal anomalies. The anterior interhemispheric effective and functional connectivity are elevated in the spina bifida group, a result that may reflect compensatory mechanisms. In contrast, the intrahemispheric effective connectivity is comparable in the two groups. The differences between the spina bifida and control groups are most significant in the θ and α bands.

  11. Efferent connections of the rostral portion of medial agranular cortex in rats.

    PubMed

    Reep, R L; Corwin, J V; Hashimoto, A; Watson, R T

    1987-08-01

    This study of the rostral part of medial agranular cortex (AGm) was undertaken with two principal aims in mind. First, to delineate the efferent connections of AGm and compare these with the pattern of afferents defined by us in a previous study. Second, to provide a firmer basis for anatomical and functional comparisons with cortical regions in monkeys. Autoradiographic, horseradish peroxidase, and fiber degeneration techniques were used. Rostral AGm has a variety of corticocortical connections--with lateral agranular motor cortex (AGl); visual, auditory, and somatic sensory regions; and limbic/paralimbic areas including orbital, insular, perirhinal, entorhinal, retrosplenial and presubicular fields. The projections to orbital, perirhinal and entorhinal cortices are bilateral. Thalamic projections of rostral AGm are concentrated in the ventral lateral, central lateral, paracentral, mediodorsal and ventromedial nuclei. Moderate terminal fields are consistently seen in the reticular, anteromedial, central medial, gelatinosus, parafascicular, and posterior nuclei. More caudal projections reach the central gray, superior colliculus and pontine gray. The efferents of the adjacent AGl were also examined. Although many of these overlapped those of rostral AGm, there were no efferents to visual or auditory cortex and limbic/paralimbic projections were reduced. Thalamic projections were more focused in the ventral lateral and posterior nuclei and there were no terminal fields in the central gray or superior colliculus. Based on its afferent and efferent connections, role in contralateral neglect, and the results of microstimulation studies, rostral AGm can be viewed as a multimodal association area with strong ties to the motor system. On these structural and functional grounds, rostral AGm bears certain striking resemblances to the frontal eye field, supplementary motor, and arcuate premotor areas of monkey cortex.

  12. Connections of the corticomedial amygdala in the golden hamster. I. Efferents of the ''vomeronasal amygdala''

    SciTech Connect

    Kevetter, G.A.; Winans, S.S.

    1981-03-20

    The medial (M) an posteromedial cortical (C3) amygdaloid nuclei and the nucleus of the accessory olfactory tract (NAOT) are designated the ''vomeronasal amygdala'' because they are the only components of the amygdala to receive a direct projection from the accessory olfactory bulb (AOB). The efferents of M and C3 were traced after injections of /sup 3/H-proline into the amygdala in male golden hamsters. Frozen sections of the brains were processed for autoradiography. The efferents of the ''vomeronasal amygdala'' are largely to areas which are primary and secondary terminal areas along the vomeronasal pathway, although the efferents from C3 and M terminate in different layers in these areas than do the projections from the vomeronasal nerve or the AOB. Specifically, C3 projects ipsilaterally to the internal granule cell layer of the AOB, the cellular layer of NAOT, and layer Ib of M. Additional fibers from C3 terminate in a retrocommissural component of the bed nucleus of the strain terminalis (BNST) bilaterally, and in the cellular layers of the contralateral C3. The medial nucleus projects to the cellular layer of the ipsilateral NAOT, layer Ib of C3, and bilaterally to the medial component of BNST. Projections from M to non-vomeronasal areas terminate in the medial preoptic area-anterior hypothalamic junction, ventromedial nucleus of the hypothalamus, ventral premammillary nucleus and possibly in the ventral subiculum. These results demonstrate reciprocal connections between primary and secondary vomeronasal areas between the secondary areas themselves. They suggest that M, but not C3, projects to areas outside this vomeronasal network. The medial amygdaloid nucleus is therefore an important link between the vomeronasal organ and areas of the brain not receiving direct vomeronasal input.

  13. 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

  14. Efferent connections of the "olfactostriatum": a specialized vomeronasal structure within the basal ganglia of snakes.

    PubMed

    Martinez-Marcos, Alino; Ubeda-Bañon, Isabel; Lanuza, Enrique; Halpern, Mimi

    2005-05-01

    The olfactostriatum is a portion of the basal ganglia of snakes that receives substantial vomeronasal afferents through projections from the nucleus sphericus. In a preceding article, the olfactostriatum of garter snakes (Thamnophis sirtalis) was characterized on the basis of chemoarchitecture (distribution of serotonin, neuropeptide Y and tyrosine hydroxylase) and pattern of afferent connections [Martinez-Marcos, A., Ubeda-Banon, I., Lanuza, E., Halpern, M., 2005. Chemoarchitecture and afferent connections of the "olfactostriatum": a specialized vomeronasal structure within the basal ganglia of snakes. J. Chem. Neuroanat. 29, 49-69]. In the present study, its efferent connections have been investigated. The olfactostriatum projects to the main and accessory olfactory bulbs, lateral cortex, septal complex, ventral pallidum, external, ventral anterior and dorsolateral amygdalae, bed nucleus of the stria terminalis, preoptic area, lateral posterior hypothalamic nucleus, ventral tegmental area, substantia nigra and raphe nuclei. Tracer injections in the nucleus accumbens proper, a structure closely associated with the olfactostriatum, result in a similar pattern of efferent connections with the exception of those reaching the main and accessory olfactory bulbs, lateral cortex, external, ventral anterior and dorsolateral amygdalae and bed nucleus of the stria terminalis. These data, therefore, help to characterize the olfactostriatum, an apparently specialized area of the nucleus accumbens. Double labeling experiments after tracer injections in the nucleus sphericus and the lateral posterior hypothalamic nucleus demonstrate a pathway between these two structures through the olfactostriatum. Injections in the olfactostriatum and in the medial amygdala show parallel projections to the lateral posterior hypothalamic nucleus. Since this hypothalamic nucleus has been previously described as projecting to the hypoglossal nucleus, both, the medial amygdala and the

  15. Afferent and Efferent Connections of the Cortex-Amygdala Transition Zone in Mice.

    PubMed

    Cádiz-Moretti, Bernardita; Abellán-Álvaro, María; Pardo-Bellver, Cecília; Martínez-García, Fernando; Lanuza, Enrique

    2016-01-01

    The transitional zone between the ventral part of the piriform cortex and the anterior cortical nucleus of the amygdala, named the cortex-amygdala transition zone (CxA), shows two differential features that allow its identification as a particular structure. First, it receives dense cholinergic and dopaminergic innervations as compared to the adjacent piriform cortex and amygdala, and second, it receives projections from the main and accessory olfactory bulbs. In this work we have studied the pattern of afferent and efferent projections of the CxA, which are mainly unknown, by using the retrograde tracer Fluorogold and the anterograde tracer biotinylated dextranamine. The results show that the CxA receives a relatively restricted set of intratelencephalic connections, originated mainly by the olfactory system and basal forebrain, with minor afferents from the amygdala. The only relevant extratelencephalic afference originates in the ventral tegmental area (VTA). The efferent projections of the CxA reciprocate the inputs from the piriform cortex and olfactory amygdala. In addition, the CxA projects densely to the basolateral amygdaloid nucleus and the olfactory tubercle. The extratelencephalic projections of the CxA are very scarce, and target mainly hypothalamic structures. The pattern of connections of the CxA suggests that it is indeed a transitional area between the piriform cortex and the cortical amygdala. Double labeling with choline acetyltransferase indicates that the afferent projection from the basal forebrain is the origin of its distinctive cholinergic innervation, and double labeling with dopamine transporter shows that the projection from the VTA is the source of dopaminergic innervation. These connectivity and neurochemical features, together with the fact that it receives vomeronasal in addition to olfactory information, suggest that the CxA may be involved in processing olfactory information endowed with relevant biological meaning, such as odors

  16. Afferent and Efferent Connections of the Cortex-Amygdala Transition Zone in Mice

    PubMed Central

    Cádiz-Moretti, Bernardita; Abellán-Álvaro, María; Pardo-Bellver, Cecília; Martínez-García, Fernando; Lanuza, Enrique

    2016-01-01

    The transitional zone between the ventral part of the piriform cortex and the anterior cortical nucleus of the amygdala, named the cortex-amygdala transition zone (CxA), shows two differential features that allow its identification as a particular structure. First, it receives dense cholinergic and dopaminergic innervations as compared to the adjacent piriform cortex and amygdala, and second, it receives projections from the main and accessory olfactory bulbs. In this work we have studied the pattern of afferent and efferent projections of the CxA, which are mainly unknown, by using the retrograde tracer Fluorogold and the anterograde tracer biotinylated dextranamine. The results show that the CxA receives a relatively restricted set of intratelencephalic connections, originated mainly by the olfactory system and basal forebrain, with minor afferents from the amygdala. The only relevant extratelencephalic afference originates in the ventral tegmental area (VTA). The efferent projections of the CxA reciprocate the inputs from the piriform cortex and olfactory amygdala. In addition, the CxA projects densely to the basolateral amygdaloid nucleus and the olfactory tubercle. The extratelencephalic projections of the CxA are very scarce, and target mainly hypothalamic structures. The pattern of connections of the CxA suggests that it is indeed a transitional area between the piriform cortex and the cortical amygdala. Double labeling with choline acetyltransferase indicates that the afferent projection from the basal forebrain is the origin of its distinctive cholinergic innervation, and double labeling with dopamine transporter shows that the projection from the VTA is the source of dopaminergic innervation. These connectivity and neurochemical features, together with the fact that it receives vomeronasal in addition to olfactory information, suggest that the CxA may be involved in processing olfactory information endowed with relevant biological meaning, such as odors

  17. Identification of Eye-Specific Domains and Their Relation to Callosal Connections in Primary Visual Cortex of Long Evans Rats

    PubMed Central

    Laing, R.J.; Turecek, J.; Takahata, T.; Olavarria, J.F.

    2015-01-01

    Ocular dominance columns (ODCs) exist in many primates and carnivores, but it is believed that they do not exist in rodents. Using a combination of transneuronal tracing, in situ hybridization for Zif268 and electrophysiological recordings, we show that inputs from both eyes are largely segregated in the binocular region of V1 in Long Evans rats. We also show that, interposed between this binocular region and the lateral border of V1, there lies a strip of cortex that is strongly dominated by the contralateral eye. Finally, we show that callosal connections colocalize primarily with ipsilateral eye domains in the binocular region and with contralateral eye input in the lateral cortical strip, mirroring the relationship between patchy callosal connections and specific sets of ODCs described previously in the cat. Our results suggest that development of cortical modular architecture is more conserved among rodents, carnivores, and primates than previously thought. PMID:24969475

  18. Deafferentation-induced plasticity of visual callosal connections: predicting critical periods and analyzing cortical abnormalities using diffusion tensor imaging.

    PubMed

    Olavarria, Jaime F; Bock, Andrew S; Leigland, Lindsey A; Kroenke, Christopher D

    2012-01-01

    Callosal connections form elaborate patterns that bear close association with striate and extrastriate visual areas. Although it is known that retinal input is required for normal callosal development, there is little information regarding the period during which the retina is critically needed and whether this period correlates with the same developmental stage across species. Here we review the timing of this critical period, identified in rodents and ferrets by the effects that timed enucleations have on mature callosal connections, and compare it to other developmental milestones in these species. Subsequently, we compare these events to diffusion tensor imaging (DTI) measurements of water diffusion anisotropy within developing cerebral cortex. We observed that the relationship between the timing of the critical period and the DTI-characterized developmental trajectory is strikingly similar in rodents and ferrets, which opens the possibility of using cortical DTI trajectories for predicting the critical period in species, such as humans, in which this period likely occurs prenatally. Last, we discuss the potential of utilizing DTI to distinguish normal from abnormal cerebral cortical development, both within the context of aberrant connectivity induced by early retinal deafferentation, and more generally as a potential tool for detecting abnormalities associated with neurodevelopmental disorders.

  19. Afferent and efferent connections of the nucleus rotundus demonstrated by WGA-HRP in the chick.

    PubMed

    Hu, M; Naito, J; Chen, Y; Ohmori, Y; Fukuta, K

    2003-12-01

    Organization of the fibre connections in the chick nucleus rotundus (Rt) was investigated by an axonal tracing method using wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). After an injection of WGA-HRP into the Rt, labelled neurones were observed in the striatum griseum centrale (SGC) in both sides of the tectum (TO) and in the ipsilateral nucleus subpretectalis/nucleus interstito-pretecto-subpretectalis (SP/IPS). Labelled fibres and terminals were also found in the ipsilateral ectostriatum (Ect). These fibre connections were topographically organized rostrocaudally. In the TO-Rt projection, the rostral and the dorsocaudal parts of the Rt received afferents from the superficial part of the SGC, the middle part of the Rt received afferents from the intermediate part of the SGC, and the ventrocaudal part of the Rt received mainly fibres from the deep part of the SGC. These topographic projections were accompanied by a considerable number of diffuse projections to the thalamic regions surrounding the Rt. In addition, the rostral and middle caudal parts of the Rt received afferents from the lateral and medial parts of the SP/IPS, respectively, and respective parts of the Rt sent efferents to the lateral and medial parts of the Ect.

  20. Connections of the corticomedial amygdala in the golden hamster. II. Efferents of the ''olfactory amygdala''

    SciTech Connect

    Kevetter, G.A.; Winans, S.S.

    1981-03-20

    The anterior cortical (C1) and posterolateral cortical (C2) nuclei of the amygdala are designated the ''olfactory amygdala'' because they each receive direct projections from the main olfactory bulb. The efferents of these nuclei were traced after stereotaxic placement of 1-5 muCi tritiated proline in the corticomedial amygdala of the male golden hamsters. Following survival times of 12, 24, or 48 hours, 20 micron frozen sections of the brains were processed for light microscopic autoradiography. Efferents from C2 terminate in layers II and III of the olfactory tubercle and in layer Ib of pars ventralis and pars medialis of the anterior olfactory nucleus. Fibers from this nucleus also project to layers I and II of the infralimbic cortex and to the molecular layer of the agranular insular cortex. More posteriorly, fibers from C2 terminate in layer I of the dorsolateral entorhinal cortex, and in the endopiriform nucleus. From C1, efferent fibers travel in the stria terminalis and terminate in the precommissural bed nucleus of the stria terminalis and in the mediobasal hypothalamus. Efferents from C1 also innervate the molecular layer of C2, the amygdalo-hippocampal area, and the adjacent piriform cortex. Neurons in both C1 and C2 project to the molecular layer of the medial amygdaloid nucleus and the posteromedial cortical nucleus of the amygdala, the plexiform layer of the ventral subiculum, and the molecular layer of the lateral entorhinal cortex.

  1. Functional expansion of sensorimotor representation and structural reorganization of callosal connections in lower limb amputees.

    PubMed

    Simões, Elington L; Bramati, Ivanei; Rodrigues, Erika; Franzoi, Ana; Moll, Jorge; Lent, Roberto; Tovar-Moll, Fernanda

    2012-02-29

    Previous studies have indicated that amputation or deafferentation of a limb induces functional changes in sensory (S1) and motor (M1) cortices, related to phantom limb pain. However, the extent of cortical reorganization after lower limb amputation in patients with nonpainful phantom phenomena remains uncertain. In this study, we combined functional magnetic resonance (fMRI) and diffusion tensor imaging (DTI) to investigate the existence and extent of cortical and callosal plasticity in these subjects. Nine "painless" patients with lower limb amputation and nine control subjects (sex- and age-matched) underwent a 3-T MRI protocol, including fMRI with somatosensory stimulation. In amputees, we observed an expansion of activation maps of the stump in S1 and M1 of the deafferented hemisphere, spreading to neighboring regions that represent the trunk and upper limbs. We also observed that tactile stimulation of the intact foot in amputees induced a greater activation of ipsilateral S1, when compared with controls. These results demonstrate a functional remapping of S1 in lower limb amputees. However, in contrast to previous studies, these neuroplastic changes do not appear to be dependent on phantom pain but do also occur in those who reported only the presence of phantom sensation without pain. In addition, our findings indicate that amputation of a limb also induces changes in the cortical representation of the intact limb. Finally, DTI analysis showed structural changes in the corpus callosum of amputees, compatible with the hypothesis that phantom sensations may depend on inhibitory release in the sensorimotor cortex.

  2. Connectivity and the corpus callosum in autism spectrum conditions: insights from comparison of autism and callosal agenesis.

    PubMed

    Booth, Rhonda; Wallace, Gregory L; Happé, Francesca

    2011-01-01

    Neural models of autism spectrum disorders (ASDs) have moved, in recent years, from a lesion model to a focus on abnormal connectivity. In this chapter, we review this work and summarize findings from our recent research comparing autism and agenesis of the corpus callosum (AgCC). We discuss our findings in the context of the "fractionable triad" account and highlight three main points. First, the social aspects of autism can be found in isolation, not accompanied by the nonsocial features of this disorder, supporting a view of autism as a "compound," rather than "monolithic," condition. Second, many young people with callosal agenesis show theory of mind- and emotion-processing deficits akin to those seen in autism. Diagnostic overshadowing may mean these people do not receive interventions that have proven beneficial in ASD. Last, study of AgCC shows that it is possible, in some cases, to develop good social cognitive skills in the absence of the corpus callosum, presenting a challenge to future connectivity models of autism.

  3. Afferent and efferent connections of the diencephalic prepacemaker nucleus in the weakly electric fish, Eigenmannia virescens: interactions between the electromotor system and the neuroendocrine axis.

    PubMed

    Wong, C J

    1997-06-23

    The afferent and efferent connections of the gymnotiform central posterior nucleus of the dorsal thalamus and prepacemaker nucleus (CP/PPn) were examined by retrograde and anterograde transport of the small molecular weight tracer, Neurobiotin. The CP/PPn was identified by physiological assay and received a local iontophoretic injection of Neurobiotin. Retrogradely labeled somata were observed in the ventral telencephalon, hypothalamus, and the pretectal nucleus electrosensorius. Anterogradely labeled fibers were traced from the CP/PPn to the ventral telencephalon, the hypothalamus, the neuropil immediately adjacent to the most rostral subdivision of the nucleus electrosensorius, the optic tectum, and the pacemaker nucleus. Retrograde transport of tracer following injections into the ventral telencephalon, preoptic area, lateral hypothalamus, tectum, and pacemaker nucleus confirmed these efferent targets. A rostromedial subarea of the CP/PPn can be identified that projects to basal forebrain regions and to a lateral region of the CP/PPn that contains afferents to the pacemaker. Many of the targets, which are connected with the CP/PPn, have been linked to reproductive behavior or neuroendocrine control in other fishes. A comparative analysis reveals that the efferent pathways of the CP/PPn appear similar and may be homologous to efferent pathways of some components of the auditory thalamus among tetrapods.

  4. The efferent connections of the olfactory bulb and accessory olfactory bulb in the snakes, Thamnophis sirtalis and Thamnophis radix.

    PubMed

    Halpern, M

    1976-10-01

    The efferent connections of the olfactory bulb and accessory olfactory bulb of two species of garter snakes, Thamnophis sirtalis and T. radix were studied with experimental anterograde degeneration techniques. Axons of cells located in the olfactory bulb terminate ipsilaterally in all parts of the anterior olfactory nucleus, olfactory tubercle and lateral pallium. In addition, some axons enter the ipsilateral stria medullaris thalami, cross the midline in the habenular commissure, enter the contralateral stria medullaris thalami and terminate in the contralateral lateral pallium. The axons of cells in the accessory olfactory bulb course through the telencephalon completely separated from the fibers of olfactory bulb origin and terminate predominantly in the nucleus sphericus. These results confirm previous reports of the separation between the central projections of the olfactory and vomeronasal systems in a variety of vertebrates. The totality of the separation between these two systems coupled with the extensive development of the vomeronasal-accessory bulb system in these snakes suggests that they may be ideal subjects for further research on the functional significance of the vomeronasal system.

  5. 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.

  6. Afferent and efferent connections of the nucleus sphericus in the snake Thamnophis sirtalis: convergence of olfactory and vomeronasal information in the lateral cortex and the amygdala.

    PubMed

    Lanuza, E; Halpern, M

    1997-09-08

    This paper is an account of the afferent and efferent projections of the nucleus sphericus (NS), which is the major secondary vomeronasal structure in the brain of the snake Thamnophis sirtalis. There are four major efferent pathways from the NS: 1) a bilateral projection that courses, surrounding the accessory olfactory tract, and innervates several amygdaloid nuclei (nucleus of the accessory olfactory tract, dorsolateral amygdala, external amygdala, and ventral anterior amygdala), the rostral parts of the dorsal and lateral cortices, and the accessory olfactory bulb; 2) a bilateral projection that courses through the medial forebrain bundle and innervates the olfactostriatum (rostral and ventral striatum); 3) a commissural projection that courses through the anterior commissure and innervates mainly the contralateral NS; and 4) a meager bilateral projection to the lateral hypothalamus. On the other hand, important afferent projections to the NS arise solely in the accessory olfactory bulb, the nucleus of the accessory olfactory tract, and the contralateral NS. This pattern of connections has three important implications: first, the lateral cortex probably integrates olfactory and vomeronasal information. Second, because the NS projection to the hypothalamus is meager and does not reach the ventromedial hypothalamic nucleus, vomeronasal information from the NS is not relayed directly to that nucleus, as previously reported. Finally, a structure located in the rostral and ventral telencephalon, the olfactostriatum, stands as the major tertiary vomeronasal center in the snake brain. These three conclusions change to an important extent our previous picture of how vomeronasal information is processed in the brain of reptiles.

  7. The mormyrid mesencephalon. II. The medio-dorsal nucleus of the torus semicircularis: afferent and efferent connections studied with the HRP method.

    PubMed

    Haugedé-Carré, F

    1983-05-23

    The connections of the medio-dorsal nucleus (nMD) were established with the HRP tracing method in two mormyrid species, Brienomyrus niger and Gnathonemus petersii. The medio-dorsal nucleus (nMD) is the second largest nucleus of the mormyrid torus semicircularis which comprises 7 nuclei. According to our histological observations, the nMD is composed of three regions: anterior (a), medialis (m) and posterior (p), each has distinct connections. The nMD receives medullary, rhombencephalic inputs, and mesencephalic inputs. The rhombencephalic afferents arising from the acoustico-lateral area constitute the most extensive projection: they arise from nucleus octavius, nuclear anterior and a 'crest cell layer'. The largest part of these rhombo-mesencephalic connections is bilateral. The bifurcated axons are gathered in the pars medialis of the lemnisci laterales and end, respectively, in the three subdivisions--pars posterior, pars medialis, pars anterior--of the nMD. The contralateral projections are larger than the ipsilateral ones except for the octavo-mesencephalic projection, where the ipsilateral is predominant. Collaterals of these axons end bilaterally in the mesencephalic paralemniscal nuclei (nPL). The mesencephalic afferents originate in the contralateral nPL, while medullary afferents arise in the contralateral nucleus subfunicularis (nSF). None of these projections show topological specificity within the nMD. Concerning the efferent connections, the nMD projects to the ipsilateral tectum opticum and valvula cerebelli.

  8. 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

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

    2015-09-01

    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 (Iba et al., J Neurosci 33:1024-1037, 2013) 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

  9. Negotiating First Graders' Reading Stance: The Relationship between Their Efferent and Aesthetic Connections and Their Reading Comprehension

    ERIC Educational Resources Information Center

    Pilonieta, Paola; Hancock, Stephen D.

    2012-01-01

    Due to changing demographics, our students are coming into schools with diverse life experiences, which do not always reflect the cultural reality of their schools. Given the research on the importance of using literature that is relevant to the students' background, this study sought to explore how first grade urban students connect to literature…

  10. 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.

  11. A connection between the Efferent Auditory System and Noise-Induced Tinnitus Generation. Reduced contralateral suppression of TEOAEs in patients with noise-induced tinnitus

    PubMed Central

    Lalaki, Panagiota; Hatzopoulos, Stavros; Lorito, Guiscardo; Kochanek, Krzysztof; Sliwa, Lech; Skarzynski, Henryk

    2011-01-01

    Summary Background Subjective tinnitus is an auditory perception that is not caused by external stimulation, its source being anywhere in the auditory system. Furthermore, evidence exists that exposure to noise alters cochlear micromechanics, either directly or through complex feed-back mechanisms, involving the medial olivocochlear efferent system. The aim of this study was to assess the role of the efferent auditory system in noise-induced tinnitus generation. Material/Methods Contralateral sound-activated suppression of TEOAEs was performed in a group of 28 subjects with noise-induced tinnitus (NIT) versus a group of 35 subjects with normal hearing and tinnitus, without any history of exposure to intense occupational or recreational noise (idiopathic tinnitus-IT). Thirty healthy, normally hearing volunteers were used as controls for the efferent suppression test. Results Suppression of the TEOAE amplitude less than 1 dB SPL was considered abnormal, giving a false positive rate of 6.7%. Eighteen out of 28 (64.3%) patients of the NIT group and 9 out of 35 (25.7%) patients of the IT group showed abnormal suppression values, which were significantly different from the controls’ (p<0.0001 and p<0.045, respectively). Conclusions The abnormal activity of the efferent auditory system in NIT cases might indicate that either the activity of the efferent fibers innervating the outer hair cells (OHCs) is impaired or that the damaged OHCs themselves respond abnormally to the efferent stimulation. PMID:21709642

  12. Visualization of neurons filled with biotinylated-lucifer yellow following identification of efferent connectivity with retrograde transport.

    PubMed

    Hill, S J; Oliver, D L

    1993-01-01

    A new method is described that allows identification of neurons by retrograde transport, intracellular injection of biotin-labeled Lucifer Yellow, and a histochemical reaction of the biotin. Cells in the inferior colliculus that project to the ipsilateral thalamus are identified by injection of rhodamine-labeled latex beads into the medial geniculate body and retrograde transport in vivo. Several days later, the brains are fixed with aldehydes, and the inferior colliculus is cut on a vibratome. The rhodamine-labeled cells are observed with epi-fluorescent optics, impaled with intracellular pipettes under visual control, and injected with 9% Lucifer Yellow dilithium salt and 1% Lucifer Yellow cadaverine biotin-X. The biotinylated Lucifer Yellow is visualized by incubation of the slice overnight in avidin-biotin-HRP complex in the presence of 0.1% Triton X-100 at 4 degrees C. A diaminobenzidine reaction with simultaneous cobalt and nickel intensification follows. This method produces well-filled neuronal cell bodies, dendrites, and spines for light microscopic analysis. The non-fluorescent reaction product in these intracellularly filled cells may permit transmitter immunohistochemistry and synaptic fine structure to be studied in combination with neural connections and dendritic morphology.

  13. Efferent connections of an auditory area in the caudal insular cortex of the rat: anatomical nodes for cortical streams of auditory processing and cross-modal sensory interactions.

    PubMed

    Kimura, A; Imbe, H; Donishi, T

    2010-04-14

    In the rat cortex, the two non-primary auditory areas, posterodorsal and ventral auditory areas, may constitute the two streams of auditory processing in their distinct projections to the posterior parietal and insular cortices. The posterior parietal cortex is considered crucial for auditory spatial processing and directed attention, while possible auditory function of the insular cortex is largely unclear. In this study, we electrophysiologically delineated an auditory area in the caudal part of the granular insular cortex (insular auditory area, IA) and examined efferent connections of IA with anterograde tracer biocytin to deduce the functional significance of IA. IA projected to the rostral agranular insular cortex, a component of the lateral prefrontal cortex. IA also projected to the adjacent dysgranular insular cortex and the caudal agranular insular cortex and sent feedback projections to cortical layer I of the primary and secondary somatosensory areas. Corticofugal projections terminated in auditory, somatosensory and visceral thalamic nuclei, and the bottom of the thalamic reticular nucleus that could overlap the visceral sector. The ventral part of the caudate putamen, the external cortex of the inferior colliculus and the central amygdaloid nucleus were also the main targets. IA exhibited neural response to transcutaneous electrical stimulation of the forepaw in addition to acoustic stimulation (noise bursts and pure tones). The results suggest that IA subserves diverse functions associated with somatosensory, nociceptive and visceral processing that may underlie sound-driven emotional and autonomic responses. IA, being potentially involved in such extensive cross-modal sensory interactions, could also be an important anatomical node of auditory processing linked to higher neural processing in the prefrontal cortex.

  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. CalloseMeasurer: a novel software solution to measure callose deposition and recognise spreading callose patterns

    PubMed Central

    2012-01-01

    Background Quantification of callose deposits is a useful measure for the activities of plant immunity and pathogen growth by fluorescence imaging. For robust scoring of differences, this normally requires many technical and biological replicates and manual or automated quantification of the callose deposits. However, previously available software tools for quantifying callose deposits from bioimages were limited, making batch processing of callose image data problematic. In particular, it is challenging to perform large-scale analysis on images with high background noise and fused callose deposition signals. Results We developed CalloseMeasurer, an easy-to-use application that quantifies callose deposition, a plant immune response triggered by potentially pathogenic microbes. Additionally, by tracking identified callose deposits between multiple images, the software can recognise patterns of how a given filamentous pathogen grows in plant leaves. The software has been evaluated with typical noisy experimental images and can be automatically executed without the need for user intervention. The automated analysis is achieved by using standard image analysis functions such as image enhancement, adaptive thresholding, and object segmentation, supplemented by several novel methods which filter background noise, split fused signals, perform edge-based detection, and construct networks and skeletons for extracting pathogen growth patterns. To efficiently batch process callose images, we implemented the algorithm in C/C++ within the Acapella™ framework. Using the tool we can robustly score significant differences between different plant genotypes when activating the immune response. We also provide examples for measuring the in planta hyphal growth of filamentous pathogens. Conclusions CalloseMeasurer is a new software solution for batch-processing large image data sets to quantify callose deposition in plants. We demonstrate its high accuracy and usefulness for two

  16. CalloseMeasurer: a novel software solution to measure callose deposition and recognise spreading callose patterns.

    PubMed

    Zhou, Ji; Spallek, Thomas; Faulkner, Christine; Robatzek, Silke

    2012-12-17

    Quantification of callose deposits is a useful measure for the activities of plant immunity and pathogen growth by fluorescence imaging. For robust scoring of differences, this normally requires many technical and biological replicates and manual or automated quantification of the callose deposits. However, previously available software tools for quantifying callose deposits from bioimages were limited, making batch processing of callose image data problematic. In particular, it is challenging to perform large-scale analysis on images with high background noise and fused callose deposition signals. We developed CalloseMeasurer, an easy-to-use application that quantifies callose deposition, a plant immune response triggered by potentially pathogenic microbes. Additionally, by tracking identified callose deposits between multiple images, the software can recognise patterns of how a given filamentous pathogen grows in plant leaves. The software has been evaluated with typical noisy experimental images and can be automatically executed without the need for user intervention. The automated analysis is achieved by using standard image analysis functions such as image enhancement, adaptive thresholding, and object segmentation, supplemented by several novel methods which filter background noise, split fused signals, perform edge-based detection, and construct networks and skeletons for extracting pathogen growth patterns. To efficiently batch process callose images, we implemented the algorithm in C/C++ within the Acapella™ framework. Using the tool we can robustly score significant differences between different plant genotypes when activating the immune response. We also provide examples for measuring the in planta hyphal growth of filamentous pathogens. CalloseMeasurer is a new software solution for batch-processing large image data sets to quantify callose deposition in plants. We demonstrate its high accuracy and usefulness for two applications: 1) the

  17. Decreased callosal thickness in attention-deficit/hyperactivity disorder.

    PubMed

    Luders, Eileen; Narr, Katherine L; Hamilton, Liberty S; Phillips, Owen R; Thompson, Paul M; Valle, Jessica S; Del'Homme, Melissa; Strickland, Tony; McCracken, James T; Toga, Arthur W; Levitt, Jennifer G

    2009-01-01

    Neuroimaging studies of attention-deficit/hyperactivity disorder (ADHD) have revealed structural abnormalities in the brains of affected individuals. One of the most replicated alterations is a significantly smaller corpus callosum (CC), for which conflicting reports exist with respect to the affected callosal segments. We applied novel surface-based geometrical modeling methods to establish the presence, direction, and exact location of callosal alterations in ADHD at high spatial resolution. For this purpose, we calculated the thickness of the CC at 100 equidistant midsagittal points in an age-matched male sample of 19 individuals with ADHD and 19 typically developing control subjects. In close agreement with many prior observations, the CC was shown to be significantly thinner in ADHD subjects in anterior and, particularly, posterior callosal sections. Covarying for intelligence did not significantly alter the observed ADHD effects. However, group differences were no longer present in anterior sections when covarying for brain volume and after excluding ADHD subjects comorbid for oppositional defiant disorder. Decreased callosal thickness may be associated with fewer fibers or a decrease in the myelination of fibers connecting the parietal and prefrontal cortices. This might affect interhemispheric communication channels that are necessary to sustain attention or motor control, thus contributing to symptoms of hyperactivity and impulsivity, or inattention, observed in ADHD. Future studies are necessary to determine whether callosal abnormalities reflect maturational delays or persist into adulthood.

  18. 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

  19. 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.

  20. Paradoxically greater interhemispheric transfer deficits in partial than complete callosal agenesis.

    PubMed

    Aglioti, S; Beltramello, A; Tassinari, G; Berlucchi, G

    1998-10-01

    Symptoms of interhemispheric disconnection are typically much less severe in callosal agenesis than after surgical section of the corpus callosum. Sperry [Sperry, R. W., Plasticity of neural maturation. Developmental Biology, 1968, 2 (Suppl.), 306-327.] has attributed this difference to two interconnected factors: (1) the callosal section is usually performed after the brain has lost the maximal degree of functional plasticity associated with the early stages of development and (2) the removal of an already formed structure is more disruptive for functional brain organization than the failure of the same structure to develop. It has been suggested that functional compensation is less efficient if callosal agenesis is partial rather than complete [Dennis, M., Impaired sensory and motor differentiation with corpus callosum agenesis: A lack of callosal inhibition during ontogeny? Neuropsychologia, 1976, 14, 455-469.]. This suggestion is supported by the present findings of partial left-hand anomia, partial left-field alexia and poor tactile cross-localization in a subject with a congenital absence of the posterior part of the corpus callosum due to an arteriovenous malformation. In agreement with many previous studies, similar, though more severe, symptoms of interhemispheric disconnection were found in a subject with a complete section of the corpus callosum, but not in a subject with complete callosal agenesis. Praxic control of the left hand on verbal commands was severely deficient in the callosotomy subject, but it was normal in the subject with callosal hypogenesis. The lesser degree of compensation in partial compared to complete callosal agenesis may be explained by a reduced pressure to develop extracallosal means of interhemispheric communication, contingent on the partial existence of callosal connections, as well as by the later occurrence in development of the causes of callosal hypogenesis compared to those of total callosal agenesis.

  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. Modulation of hair cell efferents

    PubMed Central

    Wersinger, Eric; Fuchs, Paul Albert

    2011-01-01

    Outer hair cells (OHCs) amplify the sound-evoked motion of the basilar membrane to enhance acoustic sensitivity and frequency selectivity. Medial olivocochlear (MOC) efferents inhibit OHCs to reduce the sound-evoked response of cochlear afferent neurons. OHC inhibition occurs through the activation of postsynaptic α9α10 nicotinic receptors tightly coupled to calcium-dependent SK2 channels that hyperpolarize the hair cell. MOC neurons are cholinergic but a number of other neurotransmitters and neuromodulators have been proposed to participate in efferent transmission, with emerging evidence for both pre- and postsynaptic effects. Cochlear inhibition in vivo is maximized by repetitive activation of the efferents, reflecting facilitation and summation of transmitter release onto outer hair cells. This review summarizes recent studies on cellular and molecular mechanisms of cholinergic inhibition and the regulation of those molecular components, in particular the involvement of intracellular calcium. Facilitation at the efferent synapse is compared in a variety of animals, as well as other possible mechanisms of modulation of ACh release. These results suggest that short-term plasticity contributes to effective cholinergic inhibition of hair cells. PMID:21187136

  3. Electrophysiological Correlates of Morphological Neuroplasticity in Human Callosal Dysgenesis.

    PubMed

    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.

  4. 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

  5. Callosal ideomotor apraxia in Alzheimer's disease.

    PubMed

    Cimino-Knight, Ann Marie; Gonzalez Rothi, Leslie J; He, Ying; Heilman, Kenneth M

    2017-02-01

    Impaired ability to perform skilled movements with the left upper limb in patients with corpus callosum injury has been well described (callosal apraxia) with some displaying spatial-temporal errors primarily in response to verbal commands (verbal callosal disconnection apraxia), with imitation, and when using actual tools (callosal ideomotor apraxia). Additionally some patients with callosal injury also make content errors when selecting and using the incorrect tool with their left upper limb (callosal conceptual apraxia). Interestingly, patients with Alzheimer's disease (AD) reveal anatomic evidence of callosal degeneration but callosal apraxia in AD has not been described. The purpose of this study was to learn whether patients with AD display forms of callosal apraxia. Participants were 22 right-handed patients with AD and 24 matched controls. Both upper limbs were tested by having subjects pantomime transitive movements to command and imitation. Participants also viewed pictures of an incomplete task and attempted to pantomime the action needed to complete the task. When compared to controls, the participants with AD demonstrated ideomotor and conceptual apraxias of both upper limbs; however, ideomotor apraxia of their left hand was more robust than that of their right hand, suggesting a hemispheric disconnection.

  6. Efferent axons in the avian auditory nerve.

    PubMed

    Köppl, C

    2001-05-01

    The sensory hair cells of the inner ear receive both afferent and efferent innervation. The efferent supply to the auditory organ has evolved in birds and mammals into a separate complex system, with several types of neurons of largely unknown function. In this study, the efferent axons in four different species of birds (chicken, starling, barn owl and emu) were examined anatomically. Total numbers of efferents supplying the cochlear duct (auditory basilar papilla and the vestibular lagenar macula) were determined; separate estimates of the efferents to the lagenar macula only were also derived and subtracted. The numbers for auditory efferents thus varied between 120 (chicken) and 1068 (barn owl). Considering the much larger numbers of hair cells in the basilar papilla, each efferent is predicted to branch extensively. However, pronounced species-specific differences as well as regional differences along the tonotopic gradient of the basilar papilla were documented. Myelinated and unmyelinated axons were found, with mean diameters of about 1 microm and about 0.5 microm, respectively. This suggests two basic populations of efferents, however, they did not appear to be distinguished sharply. Evidence is presented that some efferents lose their myelination at the transition from central oligodendrocyte to peripheral Schwann cell myelin. Finally, a comparison of the four bird species evaluated suggests that the efferent population with smaller, unmyelinated axons is the phylogenetically more primitive one. A new population probably arose in parallel with the evolution and differentiation of the specialized hair-cell type it innervates, the short hair cell.

  7. Unplugging the callose plug from sieve pores.

    PubMed

    Xie, Bo; Hong, Zonglie

    2011-04-01

    The presence of callose in sieve plates has been known for a long time, but how this polysaccharide plug is synthesized has remained unsolved. Two independent laboratories have recently reported the identification of callose synthase 7 (CalS7), also known as glucan synthase-like 7 (GSL7), as the enzyme responsible for callose deposition in sieve plates. Mutant plants defective in this enzyme failed to synthesize callose in developing sieve plates during phloem formation and were unable to accumulate callose in sieve pores in response to stress treatments. The mutant plants developed less open pores per sieve plate and the pores were smaller in diameter. As a result, phloem conductivity was reduced significantly and the mutant plants were shorter and set fewer seeds.

  8. Unplugging the callose plug from sieve pores

    PubMed Central

    Xie, Bo

    2011-01-01

    The presence of callose in sieve plates has been known for a long time, but how this polysaccharide plug is synthesized has remained unsolved. Two independent laboratories have recently reported the identification of callose synthase 7 (CalS7), also known as glucan synthase-like 7 (GSL7), as the enzyme responsible for callose deposition in sieve plates. Mutant plants defective in this enzyme failed to synthesize callose in developing sieve plates during phloem formation and were unable to accumulate callose in sieve pores in response to stress treatments. The mutant plants developed less open pores per sieve plate and the pores were smaller in diameter. As a result, phloem conductivity was reduced significantly and the mutant plants were shorter and set fewer seeds. PMID:21386663

  9. Callose synthesis during reproductive development in monocotyledonous and dicotyledonous plants.

    PubMed

    Shi, Xiao; Han, Xiao; Lu, Tie-gang

    2016-01-01

    Callose, a linear β-1,3-glucan molecule, plays important roles in a variety of processes in angiosperms, including development and the response to biotic and abiotic stress. Despite the importance of callose deposition, our understanding of the roles of callose in rice reproductive development and the regulation of callose biosynthesis is limited. GLUCAN SYNTHASE-LIKE genes encode callose synthases (GSLs), which function in the production of callose at diverse sites in plants. Studies have shown that callose participated in plant reproductive development, and that the timely deposition and degradation of callose were essential for normal male gametophyte development. In this mini-review, we described conserved sequences found in GSL family proteins from monocotyledonous (Oryza sativa and Zea mays) and dicotyledonous (Arabidopsis thaliana and Glycine max) plants. We also describe the latest findings on callose biosynthesis and deposition during reproductive development and discuss future challenges in unraveling the mechanism of callose synthesis and deposition in higher plants.

  10. Callose synthesis during reproductive development in monocotyledonous and dicotyledonous plants

    PubMed Central

    Shi, Xiao; Han, Xiao; Lu, Tie-gang

    2016-01-01

    Callose, a linear β-1,3-glucan molecule, plays important roles in a variety of processes in angiosperms, including development and the response to biotic and abiotic stress. Despite the importance of callose deposition, our understanding of the roles of callose in rice reproductive development and the regulation of callose biosynthesis is limited. GLUCAN SYNTHASE-LIKE genes encode callose synthases (GSLs), which function in the production of callose at diverse sites in plants. Studies have shown that callose participated in plant reproductive development, and that the timely deposition and degradation of callose were essential for normal male gametophyte development. In this mini-review, we described conserved sequences found in GSL family proteins from monocotyledonous (Oryza sativa and Zea mays) and dicotyledonous (Arabidopsis thaliana and Glycine max) plants. We also describe the latest findings on callose biosynthesis and deposition during reproductive development and discuss future challenges in unraveling the mechanism of callose synthesis and deposition in higher plants. PMID:26451709

  11. Developmental malformation of the corpus callosum: a review of typical callosal development and examples of developmental disorders with callosal involvement.

    PubMed

    Paul, Lynn K

    2011-03-01

    This review provides an overview of the involvement of the corpus callosum (CC) in a variety of developmental disorders that are currently defined exclusively by genetics, developmental insult, and/or behavior. I begin with a general review of CC development, connectivity, and function, followed by discussion of the research methods typically utilized to study the callosum. The bulk of the review concentrates on specific developmental disorders, beginning with agenesis of the corpus callosum (AgCC)-the only condition diagnosed exclusively by callosal anatomy. This is followed by a review of several genetic disorders that commonly result in social impairments and/or psychopathology similar to AgCC (neurofibromatosis-1, Turner syndrome, 22q11.2 deletion syndrome, Williams yndrome, and fragile X) and two forms of prenatal injury (premature birth, fetal alcohol syndrome) known to impact callosal development. Finally, I examine callosal involvement in several common developmental disorders defined exclusively by behavioral patterns (developmental language delay, dyslexia, attention-deficit hyperactive disorder, autism spectrum disorders, and Tourette syndrome).

  12. A computer model of auditory efferent suppression: implications for the recognition of speech in noise.

    PubMed

    Brown, Guy J; Ferry, Robert T; Meddis, Ray

    2010-02-01

    The neural mechanisms underlying the ability of human listeners to recognize speech in the presence of background noise are still imperfectly understood. However, there is mounting evidence that the medial olivocochlear system plays an important role, via efferents that exert a suppressive effect on the response of the basilar membrane. The current paper presents a computer modeling study that investigates the possible role of this activity on speech intelligibility in noise. A model of auditory efferent processing [Ferry, R. T., and Meddis, R. (2007). J. Acoust. Soc. Am. 122, 3519-3526] is used to provide acoustic features for a statistical automatic speech recognition system, thus allowing the effects of efferent activity on speech intelligibility to be quantified. Performance of the "basic" model (without efferent activity) on a connected digit recognition task is good when the speech is uncorrupted by noise but falls when noise is present. However, recognition performance is much improved when efferent activity is applied. Furthermore, optimal performance is obtained when the amount of efferent activity is proportional to the noise level. The results obtained are consistent with the suggestion that efferent suppression causes a "release from adaptation" in the auditory-nerve response to noisy speech, which enhances its intelligibility.

  13. 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.

  14. 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.

  15. The ischial callosities of Sulawesi macaques.

    PubMed

    Juliandi, Berry; Suryobroto, Bambang; Perwitasari-Farajallah, Dyah

    2009-12-01

    Sulawesi island has a high level of endemism, including the seven species of monkey from the genus Macaca (macaques). These monkeys have a pair of sitting pads, termed ischial callosities that have diverse shapes and previously were described verbally only. Although useful, these verbal descriptions cannot fully describe shape variation and are somewhat subjective, and cannot directly be used to analyze relationships among species. Here, we report a quantitative analysis of shape of Sulawesi macaque ischial callosities using geometric morphometric tools to optimally describe shape variation and objectively reconstruct general pattern of callosity shapes. By quantification of shape variation, we compare the relationships of each Sulawesi macaque species with each other and with the two geographically neighboring macaque species, M. nemestrina and M. fascicularis, by consensus coordinates of the callosity outlines. The Sulawesi macaques have a wider degree of variation compared with M. fascicularis and M. nemestrina; variation exists in the dorsal part and in the bending of the callosity. There are three general types of callosity shape in Sulawesi macaques: oval without bending (M. tonkeana and M. maurus), oval with outward bending (M. ochreata and M. brunnescens), and oval or reniform with inward bending (M. hecki, M. nigrescens, and M. nigra). These types are congruent with their geographical distribution. The pathway of shape change may have started from oval without bending in the center and the southern peninsula, to outward bending in the southeastern species, and to oval or reniform with inward bending in the northern species.

  16. Microsurgical anatomy of the ventral callosal radiations: new destination, correlations with diffusion tensor imaging fiber-tracking, and clinical relevance.

    PubMed

    Peltier, Johann; Verclytte, Sébastien; Delmaire, Christine; Deramond, Hervé; Pruvo, Jean-Pierre; Le Gars, Daniel; Godefroy, Olivier

    2010-03-01

    In the current literature, there is a lack of a detailed map of the origin, course, and connections of the ventral callosal radiations of the human brain. The authors used an older dissection technique based on a freezing process as well as diffusion tensor imaging to investigate this area of the human brain. The authors demonstrated interconnections between areas 11, 12, and 25 for the callosal radiations of the trunk and rostrum of the corpus callosum; between areas 9, 10, and 32 for the genu; and between areas 6, 8, and 9 for the ventral third of the body. The authors identified new ventral callosal connections crossing the rostrum between both temporal poles and coursing within the temporal stem, and they named these connections the "callosal radiations of Peltier." They found that the breadth of the callosal radiations slightly increases along their course from the rostrum to the first third of the body of the corpus callosum. The fiber dissection and diffusion tensor imaging techniques are complementary not only in their application to the study of the commissural system in the human brain, but also in their practical use for diagnosis and surgical planning. Further investigations, neurocognitive tests, and other contributions will permit elucidation of the functional relevance of the newly identified callosal radiations in patients with disease involving the ventral corpus callosum.

  17. A case of callosal agenesis with strong anatomical and functional asymmetries.

    PubMed

    Jäncke, L; Wunderlich, G; Schlaug, G; Steinmetz, H

    1997-10-01

    A 30-year-old right-handed man (W.D.) with total callosal agenesis was examined neuropsychologically and with magnetic resonance imaging. Basic neuropsychological testing revealed normal intelligence and average attentional capabilities. Anatomically, W.D. shows strong leftward perisylvian asymmetry both for the planum temporale and planum parietale, an unusual pattern not found in our database of more than 200 brains of young and healthy individuals. Functionally, W.D. has strong right hand superiority for hand skill and tactile object recognition, indicating unusual left hemisphere dominance for both functions. Our observations could support the hypothesis that callosal connectivity and hemispheric asymmetry may be inversely related.

  18. Depletion of Inositol Polyphosphate 4-Phosphatase II Suppresses Callosal Axon Formation in the Developing Mice.

    PubMed

    Ji, Liting; Kim, Nam-Ho; Huh, Sung-Oh; Rhee, Hae Jin

    2016-06-30

    The corpus callosum is a bundle of nerve fibers that connects the two cerebral hemispheres and is essential for coordinated transmission of information between them. Disruption of early stages of callosal development can cause agenesis of the corpus callosum (AgCC), including both complete and partial callosal absence, causing mild to severe cognitive impairment. Despite extensive studies, the etiology of AgCC remains to be clarified due to the complicated mechanism involved in generating AgCC. The biological function of PI3K signaling including phosphatidylinositol-3,4,5-trisphosphate is well established in diverse biochemical processes including axon and dendrite morphogenesis, but the function of the closely related phosphatidylinositol-3,4,-bisphosphate (PI(3,4)P2) signaling, particularly in the nervous system, is largely unknown. Here, we provide the first report on the role of inositol polyphosphate 4-phosphatase II (INPP4B), a PI(3,4)P2 metabolizing 4-phosphatase in the regulation of callosal axon formation. Depleting INPP4B by in utero electroporation suppressed medially directed callosal axon formation. Moreover, depletion of INPP4B significantly attenuated formation of Satb2-positive pyramidal neurons and axon polarization in cortical neurons during cortical development. Taken together, these data suggest that INPP4B plays a role in the regulating callosal axon formation by controlling axon polarization and the Satb2-positive pyramidal neuron population. Dysregulation of INPP4B during cortical development may be implicated in the generation of partial AgCC.

  19. Callosal Thickness Reductions relate to Facial Dysmorphology in Fetal Alcohol Spectrum Disorders

    PubMed Central

    Yang, Yaling; Phillips, Owen R.; Kan, Eric; Sulik, Kathleen K.; Mattson, Sarah N.; Riley, Edward P.; Jones, Kenneth L.; Adnams, Colleen M.; May, Philip A.; O’Connor, Mary J.; Narr, Katherine L.; Sowell, Elizabeth R.

    2011-01-01

    Background Structural abnormalities of the corpus callosum (CC), such as reduced size and increased shape variability, have been documented in individuals with fetal alcohol spectrum disorders (FASD). However, the regional specificity of altered CC structure, which may point to the timing of neurodevelopmental disturbances and/or relate to specific functional impairments, is unclear. Further, associations between facial dysmorphology and callosal structure remain undetermined. Method 153 participants (age range 8–16) including 82 subjects with FASD and 71 non-exposed controls were included in this study. The structural magnetic resonance imaging (sMRI) data of these subjects was collected at 3 sites (Los Angeles and San Diego, California, and Cape Town, South Africa) and analyzed using classical parcellation schemes as well as more refined surface based geometrical modeling methods to identify callosal morphological alterations in FASD at high spatial resolution. Results Reductions in callosal thickness and area, specifically in the anterior third and the splenium, were observed in FASD compared to non-exposed controls. In addition, reduced CC thickness and area significantly correlated with reduced palpebral fissure length. Conclusions Consistent with previous reports, findings suggest an adverse effect of prenatal alcohol exposure on callosal growth and further indicate that fiber pathways connecting frontal and parieto-occipital regions in each hemisphere may be particularly affected. Significant associations between callosal and facial dysmorphology provide evidence for a concurrent insult to midline facial and brain structural development in FASD. PMID:22150665

  20. Imaging spectrum of pediatric corpus callosal pathology: a pictorial review.

    PubMed

    Hyun Yoo, Jeong; Hunter, Jill

    2013-04-01

    A wide spectrum of pediatric corpus callosal diseases can occur in the pediatric age group. Cross-sectional magnetic resonance imaging plays an important role in the diagnosis of these patients. We reviewed our imaging record and collected cases of corpus callosal pathology. The purpose of this review is to illustrate the imaging features of various corpus callosal lesions encountered in children.

  1. Callose deposition in the phloem plasmodesmata and inhibition of phloem transport in citrus leaves infected with "Candidatus Liberibacter asiaticus".

    PubMed

    Koh, Eun-Ji; Zhou, Lijuan; Williams, Donna S; Park, Jiyoung; Ding, Ningyuan; Duan, Yong-Ping; Kang, Byung-Ho

    2012-07-01

    Huanglongbing (HLB) is a destructive disease of citrus trees caused by phloem-limited bacteria, Candidatus Liberibacter spp. One of the early microscopic manifestations of HLB is excessive starch accumulation in leaf chloroplasts. We hypothesize that the causative bacteria in the phloem may intervene photoassimilate export, causing the starch to over-accumulate. We examined citrus leaf phloem cells by microscopy methods to characterize plant responses to Liberibacter infection and the contribution of these responses to the pathogenicity of HLB. Plasmodesmata pore units (PPUs) connecting companion cells and sieve elements were stained with a callose-specific dye in the Liberibacter-infected leaf phloem cells; callose accumulated around PPUs before starch began to accumulate in the chloroplasts. When examined by transmission electron microscopy, PPUs with abnormally large callose deposits were more abundant in the Liberibacter-infected samples than in the uninfected samples. We demonstrated an impairment of symplastic dye movement into the vascular tissue and delayed photoassimilate export in the Liberibacter-infected leaves. Liberibacter infection was also linked to callose deposition in the sieve plates, which effectively reduced the sizes of sieve pores. Our results indicate that Liberibacter infection is accompanied by callose deposition in PPUs and sieve pores of the sieve tubes and suggest that the phloem plugging by callose inhibits phloem transport, contributing to the development of HLB symptoms.

  2. Callosal alien hand sign following a right parietal lobe infarction.

    PubMed

    Kim, Young-Do; Lee, Eek-Sung; Lee, Kwang-Soo; Kim, Joong-Seok

    2010-06-01

    Callosal alien hand syndrome is characterized primarily by intermanual conflict and is associated with an anterior callosal lesion. We report a patient who presented with topographical disorientation and the callosal type alien hand sign. An MRI of the brain showed a right parietal lobe infarction. This is a rare example of callosal alien hand sign associated with a right parietal lesion. The right parietal lobe appeared to be responsible for the callosal hand sign in this patient, possibly due to interference with peristriate outflow pathways toward the parietal zones, where visual somatosensory interactions are likely to occur. Copyright 2009 Elsevier Ltd. All rights reserved.

  3. [How I treat....corns and callosities].

    PubMed

    Hermanns-Lê, T; Piérard, G E

    2006-01-01

    Corns and callosities are the expression of a peculiar aspect of mecanobiology of the foot. They are more frequent with ageing, particularly in women. These lesions represent a risk factor for the diabetic foot. Prevention measures are important to follow in predisposed individuals. Several medicinal and non medicinal treatments have proven their efficacy.

  4. 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.

  5. A Strategy to Validate the Role of Callose-mediated Plasmodesmal Gating in the Tropic Response.

    PubMed

    Kumar, Ritesh; Wu, Shu Wei; Iswanto, Arya Bagus Boedi; Kumar, Dhinesh; Han, Xiao; Kim, Jae-Yean

    2016-04-17

    The plant hormone auxin plays an important role in many growth and developmental processes, including tropic responses to light and gravity. The establishment of an auxin gradient is a key event leading to phototropism and gravitropism. Previously, polar auxin transport (PAT) was shown to establish an auxin gradient in different cellular domains of plants. However, Han et al. recently demonstrated that for proper auxin gradient formation, plasmodesmal callose-mediated symplasmic connectivity between the adjacent cells is also a critical factor. In this manuscript, the strategy to elucidate the role of particular genes, which can affect phototropism and gravitropism by altering the symplasmic connectivity through modulating plasmodesmal callose synthesis, is discussed. The first step is to screen aberrant tropic responses from 3-day-old etiolated seedlings of mutants or over-expression lines of a gene along with the wild type. This preliminary screening can lead to the identification of a range of genes functioning in PAT or controlling symplasmic connectivity. The second screening involves the sorting of candidates that show altered tropic responses by affecting symplasmic connectivity. To address such candidates, the movement of a symplasmic tracer and the deposition of plasmodesmal callose were examined. This strategy would be useful to explore new candidate genes that can regulate symplasmic connectivity directly or indirectly during tropic responses and other developmental processes.

  6. Vestibular Efferent Activity in Squirrel Monkeys

    DTIC Science & Technology

    1990-10-01

    animals. We will stimulate the VIIIth nerves bilaterally to antidromically identify these neurons. Subsequently, we will identify sources of synaptic...system. We will record extracellularly in alert animals from the somata of antidromically identified efferent vestibular neurons to define the level of

  7. Literature-Based Exploration: Efferent and Aesthetic.

    ERIC Educational Resources Information Center

    Prather, Kathryn

    Efferent teaching asks the student to read for a predetermined answer, focusing on another person's ideas of the text's meaning. Aesthetic teaching allows for literature to be read and experienced as art through the reader's personal transaction with the text which focuses on one's own interest to create and understand the meaning. This paper…

  8. Abnormal interhemispheric motor interactions in patients with callosal agenesis.

    PubMed

    Genç, Erhan; Ocklenburg, Sebastian; Singer, Wolf; Güntürkün, Onur

    2015-10-15

    During unilateral hand movements the activity of the contralateral primary motor cortex (cM1) is increased while the activity of the ipsilateral M1 (iM1) is decreased. A potential explanation for this asymmetric activity pattern is transcallosal cM1-to-iM1 inhibitory control. To test this hypothesis, we examined interhemispheric motor inhibition in acallosal patients. We measured fMRI activity in iM1 and cM1 in acallosal patients during unilateral hand movements and compared their motor activity pattern to that of healthy controls. In controls, fMRI activation in cM1 was significantly higher than in iM1, reflecting a normal differential task-related M1 activity. Additional functional connectivity analysis revealed that iM1 activity was strongly suppressed by cM1. Furthermore, DTI analysis indicated that this contralaterally induced suppression was mediated by microstructural properties of specific callosal fibers interconnecting both M1s. In contrast, acallosal patients did not show a clear differential activity pattern between cM1 and iM1. The more symmetric pattern was due to an elevated task-related iM1 activity in acallosal patients, which was significantly higher than iM1 activity in a subgroup of gender and age-matched controls. Also, interhemispheric motor suppression was completely absent in acallosal patients. These findings suggest that absence of callosal connections reduces inhibitory interhemispheric motor interactions between left and right M1. This effect may reveal novel aspects of mechanisms in communication of two hemispheres and establishment of brain asymmetries in general.

  9. Functional organization of human occipital-callosal fiber tracts

    PubMed Central

    Dougherty, Robert F.; Ben-Shachar, Michal; Bammer, Roland; Brewer, Alyssa A.; Wandell, Brian A.

    2005-01-01

    Diffusion tensor imaging (DTI) and fiber tracking (FT) were used to measure the occipital lobe fiber tracts connecting the two hemispheres in individual human subjects. These tracts are important for normal vision. Also, damage to portions of these tracts is associated with alexia. To assess the reliability of the DTI-FT measurements, occipital-callosal projections were estimated from each subject's left and right hemispheres independently. The left and right estimates converged onto the same positions within the splenium. We further characterized the properties of the estimated occipital-callosal fiber tracts by combining them with functional MRI. We used functional MRI to identify visual field maps in cortex and labeled fibers by the cortical functional response at the fiber endpoint. This labeling reveals a regular organization of the fibers within the splenium. The dorsal visual maps (dorsal V3, V3A, V3B, V7) send projections through a large band in the middle of the splenium, whereas ventral visual maps (ventral V3, V4) send projections through the inferior-anterior corner of the splenium. The agreement between the independent left/right estimates, further supported by previous descriptions of homologous tracts in macaque, validates the DTI-FT methods. However, a principal limitation of these methods is low sensitivity: a large number of fiber tracts that connect homotopic regions of ventral and lateral visual cortex were undetected. We conclude that most of the estimated tracts are real and can be localized with a precision of 1-2 mm, but many tracts are missed because of data and algorithm limitations. PMID:15883384

  10. Callosal agenesis followed postnatally after prenatal diagnosis.

    PubMed

    Imataka, George; Nakagawa, Eiji; Kuwashima, Shigeko; Watanabe, Hiroshi; Yamanouchi, Hideo; Arisaka, Osamu

    2006-09-01

    Callosal agenesis is a congenital brain anomaly caused by embryonal hypogenesis of the corpus callosum. Concerning the neurological prognosis, epilepsy and motor disturbance are noted in some cases, while many cases are asymptomatic and the prognosis is good. We report a fetus tentatively diagnosed with hydrocephaly on prenatal echo-encephalography, which was performed without adequate explanation to and understanding of the parents. The parents had not expected an abnormality before the screening, and were subsequently not psychologically prepared for the discovery of the congenital brain anomaly on imaging. Moreover, they received no guidance on how to deal with any possible abnormalities. The pregnant mother was referred to our hospital. Prenatal MRI was performed after informed consent was obtained, and the fetus was diagnosed with callosal agenesis. The patient was followed for 5 years, and neurological development was normal. However, the parents have remained anxious while raising the child. Thus, the prenatal diagnosis of callosal agenesis in this case caused unnecessary mental burden to the parents. Here, we report the course of the case, and discuss the way prenatal ultrasonography should be used as a prenatal screening method, and the importance of counseling before the test.

  11. Efferent pathways modulate hyperactivity in inferior colliculus.

    PubMed

    Mulders, Wilhelmina Henrica A M; Seluakumaran, Kumar; Robertson, Donald

    2010-07-14

    Animal models have demonstrated that mild hearing loss caused by acoustic trauma results in spontaneous hyperactivity in the central auditory pathways. This hyperactivity has been hypothesized to be involved in the generation of tinnitus, a phantom auditory sensation. We have recently shown that such hyperactivity, recorded in the inferior colliculus, is still dependent on cochlear neural output for some time after recovery (up to 6 weeks). We have now studied the capacity of an intrinsic efferent system, i.e., the olivocochlear system, to alter hyperactivity. This system is known to modulate cochlear neural output. Anesthetized guinea pigs were exposed to a loud sound and after 2 or 3 weeks of recovery, single-neuron recordings in inferior colliculus were made to confirm hyperactivity. Olivocochlear axons were electrically stimulated and effects on cochlear neural output and on highly spontaneous neurons in inferior colliculus were assessed. Olivocochlear stimulation suppressed spontaneous hyperactivity in the inferior colliculus. This result is in agreement with our earlier finding that hyperactivity can be modulated by altering cochlear neural output. Interestingly, the central suppression was generally much larger and longer lasting than reported previously for primary afferents. Blockade of the intracochlear effects of olivocochlear system activation eliminated some but not all of the effects observed on spontaneous activity, suggesting also a central component to the effects of stimulation. More research is needed to investigate whether these central effects of olivocochlear efferent stimulation are due to central intrinsic circuitry or to coactivation of central efferent collaterals to the cochlear nucleus.

  12. Callosal function in MS patients with mild and severe callosal damage as reflected by diffusion tensor imaging.

    PubMed

    Warlop, Nele P; Fieremans, Els; Achten, Eric; Debruyne, Jan; Vingerhoets, Guy

    2008-08-21

    In this study, callosal function was behaviourally tested in MS patients with a redundant stimuli task. Reaction times to uni- and bilateral visual stimuli are recorded. Normal subjects respond faster to bilateral than to unilateral stimuli. This effect is called the redundancy gain effect. In patients with agenesis of the corpus callosum, the redundancy gain exceeds that predicted by probability summation, suggesting a mediating influence of the corpus callosum in healthy controls. The aim of this study is to investigate the effect of callosal damage on the redundancy gain in MS patients by investigating the probability summation model. Seventeen MS patients and as many matched healthy controls performed the redundancy gain task. In order to objectify callosal damage in our MS group, diffusion tensor imaging (DTI) derived measures such as fractional anisotropy (FA) and mean diffusivity (MD) in the corpus callosum were obtained. Callosal FA and MD significantly differed in our MS group compared to the healthy controls, indicating pathological callosal involvement. Since the amount of callosal damage was highly variable within the MS group, the MS cohort was split into a low and a high callosal-injured group as quantified by FA. The high FA group performed like the healthy controls, whereas violations of the probability (race) model were found for the low FA group. We conclude that behavioural measures obtained by the redundancy gain paradigm reflect callosal pathology in MS as measured by DTI.

  13. Efferent fibers to Limulus eyes synthesize and release octopamine.

    PubMed

    Batelle, B A; Evans, J A; Chamberlain, S C

    1982-06-11

    Octopamine synthesized in vitro from tyramine by Limulus lateral and ventral eyes was located by light microscopic and electron microscopic autoradiography in efferent fibers which innervate ventral photoreceptors and lateral eye ommatidia. Newly synthesized octopamine was released from efferent fibers in response to depolarization in high concentrations of potassium. We propose that octopamine is a neurotransmitter of efferent fibers that may modulate basic retinal processes such as photoreceptor sensitivity, photomechanical movements, and photoreceptive membrane turnover.

  14. Chevron osteotomy of lesser metatarsals for intractable plantar callosities.

    PubMed

    Kitaoka, H B; Patzer, G L

    1998-05-01

    We performed distal chevron osteotomy of the second, third, or fourth metatarsal for painful plantar callosities in 19 non-rheumatoid patients (16 women, 3 men; 21 feet); their mean age was 59 years (32 to 85). The mean follow-up was four years (2 to 7). The overall results were good in 16 feet, fair in two, and poor in three, with four patients still having painful plantar callosities. There was union in all feet, but transfer metatarsalgia developed in three and three required an orthosis. Distal chevron osteotomy for intractable plantar callosities was successful both clinically and radiologically in most patients.

  15. 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).

  16. Plasmodesmata without callose and calreticulin in higher plants - open channels for fast symplastic transport?

    PubMed

    Demchenko, Kirill N; Voitsekhovskaja, Olga V; Pawlowski, Katharina

    2014-01-01

    Plasmodesmata (PD) represent membrane-lined channels that link adjacent plant cells across the cell wall. PD of higher plants contain a central tube of endoplasmic reticulum (ER) called desmotubule. Membrane and lumen proteins seem to be able to move through the desmotubule, but most transport processes through PD occur through the cytoplasmic annulus (Brunkard etal., 2013). Calreticulin (CRT), a highly conserved Ca(2+)-binding protein found in all multicellular eukaryotes, predominantly located in the ER, was shown to localize to PD, though not all PD accumulate CRT. In nitrogen-fixing actinorhizal root nodules of the Australian tree Casuarina glauca, the primary walls of infected cells containing the microsymbiont become lignified upon infection. TEM analysis of these nodules showed that during the differentiation of infected cells, PD connecting infected cells, and connecting infected and adjacent uninfected cells, were reduced in number as well as diameter (Schubert etal., 2013). In contrast with PD connecting young infected cells, and most PD connecting mature infected and adjacent uninfected cells, PD connecting mature infected cells did not accumulate CRT. Furthermore, as shown here, these PD were not associated with callose, and based on their diameter, they probably had lost their desmotubules. We speculate that either this is a slow path to PD degradation, or that the loss of callose accumulation and presumably also desmotubules leads to the PD becoming open channels and improves metabolite exchange between cells.

  17. Early visual evoked potentials in callosal agenesis.

    PubMed

    Barr, Melodie S; Hamm, Jeff P; Kirk, Ian J; Corballis, Michael C

    2005-11-01

    Three participants with callosal agenesis and 12 neurologically normal participants were tested on a simple reaction time task, with visual evoked potentials collected using a high-density 128-channel system. Independent-components analyses were performed on the averaged visual evoked potentials to isolate the components of interest. Contrary to previous research with acallosals, evidence of ipsilateral activation was present in all 3 participants. Although ipsilateral visual components were present in all 4 unilateral conditions in the 2 related acallosal participants, in the 3rd, these were present only in the crossed visual field-hand conditions and not in the uncrossed conditions. Suggestions are made as to why these results differ from earlier findings and as to the neural mechanisms facilitating this ipsilateral activation.

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

    PubMed Central

    Lindstrom, SH; Nacsa, N; Blankenship, T; Fitzgerald, PG; Weller, C; Vaney, DI; Wilson, M

    2012-01-01

    The visual system of birds includes an efferent projection from a visual area, the isthmooptic 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 2 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 2μm 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 cells 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 5μm in diameter. PMID:19439107

  19. Efferent projection from the rostral ventrolateral medulla to the area postrema in rats.

    PubMed

    Frugière, A; Nunez, E; Pasaro, R; Gaytan, S; Barillot, J C

    1998-08-06

    The rostral ventrolateral medulla (RVLM) is a region of the brain primarily involved in cardiovascular control. It receives information from several areas of the brainstem, among which the area postrema (AP) and the nucleus of the solitary tract (NTS). The medial subnuclei of the solitary tract (TS) project towards the RVLM, providing cardiopulmonary information, and the AP serves information about circulatory hormones. Although the efferent pathways are well known, it is not the case for the connections from the RVLM towards the AP and the NTS. The present study was designed to examine the efferent connections from the RVLM onto the dorsal structures of the medulla: quantitatively by means of anatomical techniques, and functionally by means of electrophysiological techniques. Morphologically, Biocytin or Biotinylated dextran amine microinjections into the RVLM were followed by labelling of many fibres running towards the bulbar dorsomedial structures, with some pathways lying in the AP itself, or located in its caudal vicinity. Conversely, when microinjections of Fast Blue (FB) were made into the AP, FB-labelled cells could be observed within the RVLM. Electrophysiologically, single shock stimulation carried on AP allowed identification of axonal fibres issuing from somata located into the cardiovascular neuronal pool in the RVLM. From these results, we can assume: (1) the existence of dense efferent projection from RVLM to aspects of the dorsal vagal complex, including the AP and, among this dense projection, (2) the existence of some fibres terminating in, or crossing through the AP, and identified as conveying baroreceptor-related information, in the rat.

  20. Small tubules, surprising discoveries: from efferent ductules in the turkey to the discovery that estrogen receptor alpha is essential for fertility in the male

    PubMed Central

    Hess, R.A.

    2017-01-01

    Efferent ductules are small, delicate tubules that connect rete testis with the head of the epididymis, first identified by de Graaf in 1668. Although difficult to find in routine dissection, the ductules are an essential component of the male reproductive tract and in larger mammals occupy up more than 50% of the caput epididymidis. My introduction to research began with the study of efferent ductules in the domestic turkey, and to my surprise these small structures with kidney-like function become the core for numerous discoveries throughout my scientific career. In this review, only two discoveries that I found interesting will be discussed: cilia that line the efferent ductule lumen and estrogen receptors that play an essential role in regulating fluid reabsorption. A potential link between these two discoveries was uncovered in the study of efferent ductule effects observed in the estrogen receptor knockout mouse and following toxic exposure to the fungicide benomyl. PMID:28191043

  1. 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. (c) 2006 Wiley-Liss, Inc.

  2. Handedness and corpus callosal morphology in Williams syndrome.

    PubMed

    Martens, Marilee A; Wilson, Sarah J; Chen, Jian; Wood, Amanda G; Reutens, David C

    2013-02-01

    Williams syndrome is a neurodevelopmental genetic disorder caused by a hemizygous deletion on chromosome 7q11.23, resulting in atypical brain structure and function, including abnormal morphology of the corpus callosum. An influence of handedness on the size of the corpus callosum has been observed in studies of typical individuals, but handedness has not been taken into account in studies of callosal morphology in Williams syndrome. We hypothesized that callosal area is smaller and the size of the splenium and isthmus is reduced in individuals with Williams syndrome compared to healthy controls, and examined age, sex, and handedness effects on corpus callosal area. Structural magnetic resonance imaging scans were obtained on 25 individuals with Williams syndrome (18 right-handed, 7 left-handed) and 25 matched controls. We found that callosal thickness was significantly reduced in the splenium of Williams syndrome individuals compared to controls. We also found novel evidence that the callosal area was smaller in left-handed participants with Williams syndrome than their right-handed counterparts, with opposite findings observed in the control group. This novel finding may be associated with LIM-kinase hemizygosity, a characteristic of Williams syndrome. The findings may have significant clinical implications in future explorations of the Williams syndrome cognitive phenotype.

  3. 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

  4. 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.

  5. Preliminary investigation of debridement of plantar callosities in rheumatoid arthritis.

    PubMed

    Woodburn, J; Stableford, Z; Helliwell, P S

    2000-06-01

    To determine the effect of expert debridement of foot callosities on forefoot pain and plantar pressure distribution in rheumatoid arthritis (RA). Plantar callosities on 14 feet of eight RA patients were debrided by a single podiatrist. Measurements of subjective pain severity in the forefoot and global arthritis pain were undertaken using a visual analogue scale, repeated at 7-day intervals to the next treatment (28 days). Plantar pressures were recorded at the lesion sites using an in-shoe flexible transducer insole before and after lesion debridement. Following debridement, all patients reported symptomatic relief with an average change in pain score of 48% (P = 0.01) but the treatment effect was lost by 7 days. Immediately following scalpel debridement, peak pressures were elevated in 10 of 14 feet, whilst contact time was reduced and peak force increased. None, however, reached statistical significance. Scalpel debridement of forefoot plantar callosities reduces forefoot pain for about 7 days, but pressure distribution is not significantly altered.

  6. Callosal transfer in different subtypes of developmental dyslexia.

    PubMed

    Fabbro, F; Pesenti, S; Facoetti, A; Bonanomi, M; Libera, L; Lorusso, M L

    2001-02-01

    Sixteen controls (age 6-13) and 20 native Italian children with developmental dyslexia (age 7-15) received a test of callosal transfer of tactile information. Among the dyslexic children, 7 had a diagnosis of L-type, 7 of P-type and 6 of M-type dyslexia according to Bakker's classification. Both control children and children with dyslexia made a significantly larger number of errors in the crossed localization condition (implying callosal transfer of tactile information) vs. the uncrossed condition. In the same condition, children with dyslexia made a significantly larger number of errors than controls. In the crossed localization condition L-types and M-types made a significantly larger number of errors than P-types and controls, while there was no significant difference in performance between P-types and controls. These findings are discussed in terms of defective callosal transfer or deficient somatosensory representation in children with L- and M-dyslexia.

  7. 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.

  8. 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.

  9. [Callose accumulation during treatment of tomato (Lycopersicon esculentum L.) cells with biotic elicitors].

    PubMed

    Emel'ianov, V I; Kravchuk, Zh N; Poliakovskiĭ, S A; Dmitriev, A P

    2008-01-01

    Time-course of induced accumulation of callose in tomato cells has been studied. Localization of callose in L. esculenthum cells was investigated by fluorescent microscopy technique, and the optimal time for its determination was found. Callose accumulation in tomato cells treated with different biotic elicitors was determined. Nonlinear dependence between callose accumulation and concentration of chitin oligomers (with 3-5 N-acetylglucosamine fragments) was established. Increasing of callose accumulation in tomato cells was proportional to the increase of concentration ofchitin dimer and chitosan in the culture medium.

  10. Afferent and efferent projections of the anterior cortical amygdaloid nucleus in the mouse.

    PubMed

    Cádiz-Moretti, Bernardita; Abellán-Álvaro, María; Pardo-Bellver, Cecília; Martínez-García, Fernando; Lanuza, Enrique

    2017-09-01

    The anterior cortical amygdaloid nucleus (ACo) is a chemosensory area of the cortical amygdala that receives afferent projections from both the main and accessory olfactory bulbs. The role of this structure is unknown, partially due to a lack of knowledge of its connectivity. In this work, we describe the pattern of afferent and efferent projections of the ACo by using fluorogold and biotinylated dextranamines as retrograde and anterograde tracers, respectively. The results show that the ACo is reciprocally connected with the olfactory system and basal forebrain, as well as with the chemosensory and basomedial amygdala. In addition, it receives dense projections from the midline and posterior intralaminar thalamus, and moderate projections from the posterior bed nucleus of the stria terminalis, mesocortical structures and the hippocampal formation. Remarkably, the ACo projects moderately to the central nuclei of the amygdala and anterior bed nucleus of the stria terminalis, and densely to the lateral hypothalamus. Finally, minor connections are present with some midbrain and brainstem structures. The afferent projections of the ACo indicate that this nucleus might play a role in emotional learning involving chemosensory stimuli, such as olfactory fear conditioning. The efferent projections confirm this view and, given its direct output to the medial part of the central amygdala and the hypothalamic 'aggression area', suggest that the ACo can initiate defensive and aggressive responses elicited by olfactory or, to a lesser extent, vomeronasal stimuli. © 2017 Wiley Periodicals, Inc.

  11. Anterior commissure absence without callosal agenesis: a new brain malformation.

    PubMed

    Mitchell, T N; Stevens, J M; Free, S L; Sander, J W; Shorvon, S D; Sisodiya, S M

    2002-04-23

    The authors report a novel human brain malformation characterized by the absence of the anterior commissure without callosal agenesis, but associated with gross unilateral panhemispheric malformation incorporating subependymal heterotopia, subcortical heterotopia, and gyral abnormalities including temporal malformation and polymicrogyria. In contrast, a normal anterior commissure was found in 125 control subjects and in 113 other subjects with a range of brain malformations.

  12. 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.

  13. Enhanced redundancy gain in schizophrenics: a correlate of callosal dysfunction?

    PubMed

    Florio, Vincenzo; Marzi, Carlo A; Girelli, Andrea; Savazzi, Silvia

    2008-09-01

    An abnormal pattern of hemispheric asymmetry, possibly as a result of disturbed interhemispheric communication, is widely, albeit by no means unanimously, held as a major cause of schizophrenia. To behaviourally test interhemispheric communication in schizophrenia we used a task that has been shown to be a reliable indicator of callosal functioning, namely, the redundant signals effect (RSE). It consists of the speeding of simple reaction time when responding to double as opposed to single visual stimuli. When the stimuli in a pair are presented to different hemispheres patients who underwent total commissurotomy or suffer from callosal agenesis show a paradoxically enhanced RSE with respect to healthy controls. Therefore, if schizophrenia patients have a callosal abnormality they ought to show a similar effect. In three experiments we tested a total of 55 patients with a diagnosis of schizophrenia and 51 healthy controls. In Experiment 1 we presented unilateral single stimuli and bilateral simultaneous double stimuli. The RSE was reliably larger in schizophrenics than in controls. In Experiment 2 the temporal interval between the two stimuli in a pair was varied. We found that while in controls the RSE disappeared with interstimulus intervals longer than 17ms, in schizophrenia patients there was a RSE only for simultaneous double stimuli. Finally, in Experiment 3 we found that there was no enhanced redundancy gain in schizophrenics when the double stimuli were presented to one and the same hemisphere, and therefore, with no need for callosal transmission. All in all, the present results provide evidence of a callosal dysfunction in schizophrenia that impairs interhemispheric integration.

  14. What does motor efference copy represent? Evidence from speech production.

    PubMed

    Niziolek, Caroline A; Nagarajan, Srikantan S; Houde, John F

    2013-10-09

    How precisely does the brain predict the sensory consequences of our actions? Efference copy is thought to reflect the predicted sensation of self-produced motor acts, such as the auditory feedback heard while speaking. Here, we use magnetoencephalographic imaging (MEG-I) in human speakers to demonstrate that efference copy prediction does not track movement variability across repetitions of the same motor task. Specifically, spoken vowels were less accurately predicted when they were less similar to a speaker's median production, even though the prediction is thought to be based on the very motor commands that generate each vowel. Auditory cortical responses to less prototypical speech productions were less suppressed, resembling responses to speech errors, and were correlated with later corrective movement, suggesting that the suppression may be functionally significant for error correction. The failure of the motor system to accurately predict less prototypical speech productions suggests that the efferent-driven suppression does not reflect a sensory prediction, but a sensory goal.

  15. 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.

  16. The Efferent Medial Olivocochlear-Hair Cell Synapse

    PubMed Central

    Elgoyhen, Ana Belén; Katz, Eleonora

    2011-01-01

    Amplification of incoming sounds in the inner ear is modulated by an efferent pathway which travels back from the brain all the way to the cochlea. The medial olivocochlear system makes synaptic contacts with hair cells, where the neurotransmitter acetylcholine is released. Synaptic transmission is mediated by a unique nicotinic cholinergic receptor composed of α9 and α10 subunits, which is highly Ca2+ permeable and is coupled to a Ca2+-activated SK potassium channel. Thus, hyperpolarization of hair cells follows efferent fiber activation. In this work we review the literature that has enlightened our knowledge concerning the intimacies of this synapse. PMID:21762779

  17. 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.…

  18. Callosal microstructural abnormalities in Alzheimer's disease and alcoholism: same phenotype, different mechanisms.

    PubMed

    Pitel, Anne-Lise; Chanraud, Sandra; Sullivan, Edith V; Pfefferbaum, Adolf

    2010-10-30

    Magnetic resonance (MRI) and diffusion tensor imaging (DTI) data were acquired in 13 Alzheimer's disease (AD) patients, 15 elderly alcoholics, and 32 elderly controls. Midsagittal area, length, dorsoventral height, fractional anisotropy (FA), and mean diffusivity (MD) of the total corpus callosum and volume of the lateral ventricles were measured; area, FA, and MD were also determined for the callosal genu, body, and splenium. On DTI, both patient groups had lower FA and higher MD than controls in all callosal regions. On MRI, both patient groups had smaller genu than controls; additional size deficits were present in the alcoholism group's callosal body and the AD group's splenium. The callosal arch was higher in the AD but not the alcoholic group compared with controls. The two patient groups had larger ventricles than controls, and the AD group had larger ventricles than the alcoholic group. Callosal area correlated with its height, and callosal FA and MD correlated with ventricular volume in AD, whereas callosal area correlated only with FA in alcoholics. In AD, the disruption of the callosal integrity, which was associated with distorted callosal shape, was related to ventricular dilation, which has been shown in twin studies to be under a multitude of genetic, polygenetic, and environmental influences. Conversely, in alcoholism, disruption of callosal microstructural integrity was related to shrinkage of the corpus callosum itself.

  19. 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.

  20. 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…

  1. 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…

  2. The role of the anterior commissure in callosal agenesis.

    PubMed

    Barr, Melodie S; Corballis, Michael C

    2002-10-01

    Two individuals with callosal agenesis (J.P. and M.M.) and 10 neurologically normal participants were tested on tasks requiring interhemispheric visual integration. M.M., whose anterior commissure was within normal limits, was much worse at matching colors and letters between visual fields than within visual fields, whereas J.P., whose anterior commissure was greatly enlarged, showed no evidence of interhemispheric disconnection. This suggests that in some cases of callosal agenesis, probably a minority, an enlarged anterior commissure may compensate for the lack of the corpus callosum. Neither acallosal participant showed interhemispheric disconnection on tasks requiring integration of location and orientation, however, suggesting that the anterior commissure plays no role in such tasks. These tasks may depend on subcortical commissures, such as the intertectal commissure.

  3. A frequency-selective feedback model of auditory efferent suppression and its implications for the recognition of speech in noise.

    PubMed

    Clark, Nicholas R; Brown, Guy J; Jürgens, Tim; Meddis, Ray

    2012-09-01

    The potential contribution of the peripheral auditory efferent system to our understanding of speech in a background of competing noise was studied using a computer model of the auditory periphery and assessed using an automatic speech recognition system. A previous study had shown that a fixed efferent attenuation applied to all channels of a multi-channel model could improve the recognition of connected digit triplets in noise [G. J. Brown, R. T. Ferry, and R. Meddis, J. Acoust. Soc. Am. 127, 943-954 (2010)]. In the current study an anatomically justified feedback loop was used to automatically regulate separate attenuation values for each auditory channel. This arrangement resulted in a further enhancement of speech recognition over fixed-attenuation conditions. Comparisons between multi-talker babble and pink noise interference conditions suggest that the benefit originates from the model's ability to modify the amount of suppression in each channel separately according to the spectral shape of the interfering sounds.

  4. 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

  5. Abnormalities in auditory efferent activities in children with selective mutism.

    PubMed

    Muchnik, Chava; Ari-Even Roth, Daphne; Hildesheimer, Minka; Arie, Miri; Bar-Haim, Yair; Henkin, Yael

    2013-01-01

    Two efferent feedback pathways to the auditory periphery may play a role in monitoring self-vocalization: the middle-ear acoustic reflex (MEAR) and the medial olivocochlear bundle (MOCB) reflex. Since most studies regarding the role of auditory efferent activity during self-vocalization were conducted in animals, human data are scarce. The working premise of the current study was that selective mutism (SM), a rare psychiatric disorder characterized by consistent failure to speak in specific social situations despite the ability to speak normally in other situations, may serve as a human model for studying the potential involvement of auditory efferent activity during self-vocalization. For this purpose, auditory efferent function was assessed in a group of 31 children with SM and compared to that of a group of 31 normally developing control children (mean age 8.9 and 8.8 years, respectively). All children exhibited normal hearing thresholds and type A tympanograms. MEAR and MOCB functions were evaluated by means of acoustic reflex thresholds and decay functions and the suppression of transient-evoked otoacoustic emissions, respectively. Auditory afferent function was tested by means of auditory brainstem responses (ABR). Results indicated a significantly higher proportion of children with abnormal MEAR and MOCB function in the SM group (58.6 and 38%, respectively) compared to controls (9.7 and 8%, respectively). The prevalence of abnormal MEAR and/or MOCB function was significantly higher in the SM group (71%) compared to controls (16%). Intact afferent function manifested in normal absolute and interpeak latencies of ABR components in all children. The finding of aberrant efferent auditory function in a large proportion of children with SM provides further support for the notion that MEAR and MOCB may play a significant role in the process of self-vocalization.

  6. 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

  7. Morphogenesis of callosal arbors in the parietal cortex of hamsters.

    PubMed

    Hedin-Pereira, C; Lent, R; Jhaveri, S

    1999-01-01

    The morphogenesis of callosal axons originating in the parietal cortex was studied by anterograde labeling with Phaseolus lectin or biocytin injected in postnatal (P) hamsters aged 7-25 days. Some labeled fibers were serially reconstructed. At P7, some callosal fibers extended as far as the contralateral rhinal fissure, with simple arbors located in the homotopic region of the opposite cortical gray matter, and two or three unbranched sprouts along their trajectory. From P7 to P13, the homotopic arbors became more complex, with branches focused predominantly, but not exclusively, in the supra- and infragranular layers of the homotopic region. Simultaneously, the lateral extension of the trunk axon in the white matter became shorter, finally disappearing by P25. Arbors in the gray matter were either bilaminar (layers 2/3 and 5) or supragranular. A heterotopic projection to the lateral cortex was consistently seen at all ages; the heterotopic arbors follow a similar sequence of events to that seen in homotopic regions. These observations document that callosal axons undergo regressive tangential remodeling during the first postnatal month, as the lateral extension of the trunk fiber gets eliminated. Radially, however, significant arborization occurs in layer-specific locations. The protracted period of morphogenesis suggests a correspondingly long plastic period for this system of cortical fibers.

  8. Callosal projections in rat somatosensory cortex are altered by early removal of afferent input.

    PubMed Central

    Koralek, K A; Killackey, H P

    1990-01-01

    During the first postnatal week, the distribution of callosal projection neurons in the rat somatosensory cortex changes from a uniform to a discontinuous pattern. To determine if this change is influenced by afferent inputs to the somatosensory cortex, the effect of both early unilateral infraorbital nerve section and unilateral removal of the dorsal thalamus on the distribution of callosal projections in rat somatosensory cortex was examined. One month after either of the above manipulations at birth, the tangential distribution of callosal projections in the somatosensory cortex was examined using the combined retrograde and anterograde transport of horseradish peroxidase. Both manipulations alter the distribution of callosal projection neurons and terminations in the somatosensory cortex. After infraorbital nerve section, the distribution of callosal projections is altered in the contralateral primary somatosensory cortex. The abnormalities observed are consistent with the altered distribution of thalamocortical projections. In addition, consistent abnormalities were observed in the pattern of callosal projections of the second somatosensory area of both hemispheres. Most notably, they are absent in a portion of the region that contains the representation of the mystacial vibrissae and sinus hairs in this area. Thalamic ablation resulted in highly aberrant patterns of callosal projections in the somatosensory cortex on the operated side, where abnormal bands and clusters of callosal projections were observed in apparently random locations. These results are interpreted as evidence that both peripheral and central inputs influence the maturational changes in the distribution of callosal projection neurons. Images PMID:2304906

  9. More Than a Leak Sealant. The Mechanical Properties of Callose in Pollen Tubes1

    PubMed Central

    Parre, Elodie; Geitmann, Anja

    2005-01-01

    While callose is a well-known permeability barrier and leak sealant in plant cells, it is largely unknown whether this cell wall polymer can also serve as a load-bearing structure. Since callose occurs in exceptionally large amounts in pollen, we assessed its role for resisting tension and compression stress in this cell. The effect of callose digestion in Solanum chacoense and Lilium orientalis pollen grains demonstrated that, depending on the species, this cell wall polymer represents a major stress-bearing structure at the aperture area of germinating grains. In the pollen tube, it is involved in cell wall resistance to circumferential tension stress, and despite its absence at the growing apex, callose is indirectly involved in the establishment of tension stress resistance in this area. To investigate whether or not callose is able to provide mechanical resistance against compression stress, we subjected pollen tubes to local deformation by microindentation. The data revealed that lowering the amount of callose resulted in reduced cellular stiffness and increased viscoelasticity, thus indicating clearly that callose is able to resist compression stress. Whether this function is relevant for pollen tube mechanics, however, is unclear, as stiffened growth medium caused a decrease in callose deposition. Together, our data provide clear evidence for the capacity of cell wall callose to resist tension and compression stress, thus demonstrating that this amorphous cell wall substance can have a mechanical role in growing plant cells. PMID:15618431

  10. Inhibitory neurotransmission regulates vagal efferent activity and gastric motility

    PubMed Central

    McMenamin, Caitlin A; Travagli, R Alberto

    2016-01-01

    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

  11. Efferent Feedback Minimizes Cochlear Neuropathy from Moderate Noise Exposure

    PubMed Central

    Maison, Stéphane F.; Usubuchi, Hajime; Liberman, M. Charles

    2013-01-01

    Although protective effects of the cochlea’s efferent feedback pathways have been well documented, prior work has focused on hair cell damage and cochlear threshold elevation and, correspondingly, on the high sound pressure levels (> 100 dB SPL) necessary to produce them. Here we explore the noise-induced loss of cochlear neurons that occurs with lower intensity exposures and in the absence of permanent threshold shifts. Using confocal microscopy to count synapses between hair cells and cochlear nerve fibers, and using measurement of auditory brainstem responses and otoacoustic emissions to assess cochlear pre- and post-synaptic function, we compare the damage from a weeklong exposure to moderate-level noise (84 dB SPL) in mice with varying degrees of cochlear de-efferentation induced by surgical lesion to the olivocochlear pathway. Such exposure causes minimal acute threshold shift and no chronic shifts in mice with normal efferent feedback. In de-efferented animals, there was up to 40% loss of cochlear nerve synapses and a corresponding decline in the amplitude of the auditory brainstem response. Quantitative analysis of the de-efferentation in inner vs. outer hair cell areas suggested that outer hair cell efferents are most important in minimizing this neuropathy, presumably by virtue of their sound-evoked feedback reduction of cochlear amplification. The moderate nature of this acoustic overexposure suggests that cochlear neurons are at risk even in everyday acoustic environments, and, thus, that the need for cochlear protection is plausible as a driving force in the design of this feedback pathway. PMID:23536069

  12. Efferent inhibition of otoacoustic emissions in preterm neonates.

    PubMed

    Carvallo, Renata Mota Mamede; Sanches, Seisse Gabriela Gandolfi; Ibidi, Silvia Maria; Soares, Jordana Costa; Durante, Alessandra Spada

    2015-01-01

    Abnormalities in auditory function of newborns may occur not only because of preterm birth, but also from the use of medications and from diseases related to prematurity. To analyze the inhibitory effect from stimulation of the olivocochlear efferent system on transient evoked otoacoustic emissions in preterm neonates, comparing these data with those from full-term neonates. This was a prospective, cross-sectional, contemporary cohort study with 125 neonates, pooled into two groups: full-term (72 full-term neonates, 36 females and 36 males, born at 37-41 weeks of gestational age); and preterm (53 neonates, 28 males and 25 females, born at ≤36 weeks of gestational age, evaluated at the corrected gestational age of 37-41 weeks). Otoacoustic emissions were recorded using linear and nonlinear click-evoked stimuli, with and without contralateral stimulation. The inhibitory effect of the efferent pathway in otoacoustic emissions was different (p=0.012) between groups, and a mean reduction of 1.48dB SPL in full-term births and of 1.02dB SPL in preterm births was observed for the non-linear click-evoked stimulus. The results suggest a reduced inhibitory effect of the olivocochlear efferent system on otoacoustic emissions in preterm neonates. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  13. Medial efferent mechanisms in children with auditory processing disorders.

    PubMed

    Mishra, Srikanta K

    2014-01-01

    Auditory processing disorder (APD) affects about 2-5% of children. However, the nature of this disorder is poorly understood. Children with APD typically have difficulties in complex listening situations. One mechanism thought to aid in listening-in-noise is the medial olivocochlear (MOC) inhibition. The purpose of this review was to critically analyze the published data on MOC inhibition in children with APD to determine whether the MOC efferents are involved in these individuals. The otoacoustic emission (OAE) methods used to assay MOC reflex were examined in the context of the current understanding of OAE generation mechanisms. Relevant literature suggests critical differences in the study population and OAE methods. Variables currently known to influence MOC reflex measurements, for example, middle-ear muscle reflexes or OAE signal-to-noise ratio, were not controlled in most studies. The use of potentially weaker OAE methods and the remarkable heterogeneity across studies does not allow for a definite conclusion whether or not the MOC reflex is altered in children with APD. Further carefully designed studies are needed to confirm the involvement of MOC efferents in APD. Knowledge of efferent functioning in children with APD would be mechanistically and clinically beneficial.

  14. 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)…

  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. Study of straight metatarsal osteotomy for the treatment of plantar callosities.

    PubMed

    Kiviniemi, V J; Leppilahti, J; Jalovaara, P

    2000-01-01

    [corrected] To evaluate the outcome of transverse distal metatarsal osteotomies for intractable plantar callosity without hammer toe deformity and associated toe corns. Twenty-five plantar callosities were treated in 19 feet of 13 patients (mean age 48 years, 5 male, 8 female) with transverse distal metatarsal osteotomy. Twenty-four of the osteotomies united primarily, one after revision. After a 7-year follow-up, 23 of the callosities had healed, two of them after an oblique reosteotomy. Eight hammer toe deformities had developed in the involved rays of four feet. Eight plantar callosities had developed outside the operated rays in five feet. Hallux valgus was a frequent finding in both operated and non-operated feet. It seems that transverse distal metatarsal osteotomy is an effective treatment of intractable plantar callosities. Harmful hammer toe deformities and transfer lesions below adjacent metatarsal heads tend to develop over time.

  17. Sex differences in the incidence of total callosal agenesis in BALB/cCF mice.

    PubMed

    Manhães, Alex C; Medina, Alexandre E; Schmidt, Sergio L

    2002-06-14

    Corpus callosum (CC) development and adult morphology seems to be affected by sex. Here we analyzed the incidence of total callosal agenesis in 341 adult male and 318 female BALB/cCF mice. This strain of mice presents total or partial callosal agenesis in approximately 20-30% of its population. No significant differences were found in overall distributions of CC lengths and in average callosal lengths (totally acallosal excluded) between male and female mice. However, a highly significant difference in the incidence of total callosal agenesis was demonstrated: 18% (n=56) of the female mice presented such trait as opposed to 10% of males (n=34). This last result suggests that sex is a relevant factor in callosal development in its earliest stages of formation.

  18. 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.

  19. 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.

  20. Surgical treatment for hallux valgus with painful plantar callosities.

    PubMed

    Okuda, R; Kinoshita, M; Morikawa, J; Jotoku, T; Abe, M

    2001-03-01

    We retrospectively reviewed the results of a distal soft-tissue procedure and proximal crescentic osteotomy of the first metatarsal combined with a proximal shortening osteotomy of the second and/or third metatarsal. This was in patients who had hallux valgus with painful plantar callosities. The review covered seven years of procedures (1989-1996) in 12 patients (14 feet) averaging 53 years of age. Average follow-up was 52 months. All patients had pain at the first metatarsophalangeal joint and had metatarsalgia preoperatively. At follow-up, 11 feet had no pain at the first metatarsophalangeal joint, and three had some improvement of pain. Ten feet had no metatarsalgia, two had improvement of metatarsalgia, and two feet had transfer lesions postoperatively and required reoperation. The angle of hallux valgus averaged 40 degrees preoperatively and 13 degrees postoperatively. The intermetatarsal angle averaged 18 degrees preoperatively and 6 degrees postoperatively. Mean decreases in length of the second and third metatarsal after surgery were 5.4 mm and 4.8 mm, respectively. Our results suggested that this combined procedure for hallux valgus with painful plantar callosities may be successful, in carefully selected patients.

  1. A choice reaction time index of callosal anatomical homotopy.

    PubMed

    Desjardins, Samuel; Braun, Claude M J; Achim, André; Roberge, Carl

    2009-10-01

    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 field advantage in the Dimond paradigm. Acta Psychologica, 121, 125-136]. This was explained by the fact that there are more homotopic than heterotopic fibers in the corpus callosum. However: (1) different parts of the visual field were not equiprobably stimulated, possibly causing subtle biases, (2) the predicted cost of vertical asymmetry was tested only with bilateral stimuli, and (3) interstimulus distance was at the outer limit of callosal midline fusion (10.6 degrees ). Here, a tachistoscopic experiment with 24 normal participants replicated the between-field vertical symmetry advantage [Desjardins, S., & Braun, C. M. J. (2006). Homotopy and heterotopy and the bilateral field advantage in the Dimond paradigm. Acta Psychologica, 121,125-136.], but without irrelevant stimulation conditions and with more proximal stimuli. In addition, a significant specific cost of vertical asymmetry of 7ms was found for between-field integration over within-field integration. As far as we know, this is the first demonstration of an effect of callosal anatomical homotopy with reaction time.

  2. 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

  3. Increased callose deposition in plants lacking DYNAMIN-RELATED PROTEIN 2B is dependent upon POWDERY MILDEW RESISTANT 4.

    PubMed

    Leslie, Michelle E; Rogers, Sean W; Heese, Antje

    2016-11-01

    Callose deposition within the cell wall is a well-documented plant immune response to pathogenic organisms as well as to pathogen-/microbe- associated molecular patterns (P/MAMPs). However, the molecular mechanisms that modulate pathogen-induced callose deposition are less understood. We reported previously that Arabidopsis plants lacking the vesicle trafficking component DYNAMIN-RELATED PROTEIN 2B (DRP2B) display increased callose deposition in response to the PAMP flg22. Here, we show that increased number of flg22-induced callose deposits in drp2b leaves is fully dependent on the callose synthase POWDERY MILDEW RESISTANT 4 (PMR4). We propose that in addition to functioning in flg22-induced endocytosis of the plant receptor, FLAGELLIN SENSING 2, DRP2B may regulate the trafficking of proteins involved in callose synthesis, such as PMR4, and/or callose degradation.

  4. Callose Deposition Is Required for Somatic Embryogenesis in Plasmolyzed Eleutherococcus senticosus Zygotic Embryos

    PubMed Central

    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

  5. 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.

  6. 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.

  7. Analysis of YFP(J16)-R6/2 reporter mice and postmortem brains reveals early pathology and increased vulnerability of callosal axons in Huntington's disease.

    PubMed

    Gatto, Rodolfo G; Chu, Yaping; Ye, Allen Q; Price, Steven D; Tavassoli, Ehsan; Buenaventura, Andrea; Brady, Scott T; Magin, Richard L; Kordower, Jeffrey H; Morfini, Gerardo A

    2015-09-15

    Cumulative evidence indicates that the onset and severity of Huntington's disease (HD) symptoms correlate with connectivity deficits involving specific neuronal populations within cortical and basal ganglia circuits. Brain imaging studies and pathological reports further associated these deficits with alterations in cerebral white matter structure and axonal pathology. However, whether axonopathy represents an early pathogenic event or an epiphenomenon in HD remains unknown, nor is clear the identity of specific neuronal populations affected. To directly evaluate early axonal abnormalities in the context of HD in vivo, we bred transgenic YFP(J16) with R6/2 mice, a widely used HD model. Diffusion tensor imaging and fluorescence microscopy studies revealed a marked degeneration of callosal axons long before the onset of motor symptoms. Accordingly, a significant fraction of YFP-positive cortical neurons in YFP(J16) mice cortex were identified as callosal projection neurons. Callosal axon pathology progressively worsened with age and was influenced by polyglutamine tract length in mutant huntingtin (mhtt). Degenerating axons were dissociated from microscopically visible mhtt aggregates and did not result from loss of cortical neurons. Interestingly, other axonal populations were mildly or not affected, suggesting differential vulnerability to mhtt toxicity. Validating these results, increased vulnerability of callosal axons was documented in the brains of HD patients. Observations here provide a structural basis for the alterations in cerebral white matter structure widely reported in HD patients. Collectively, our data demonstrate a dying-back pattern of degeneration for cortical projection neurons affected in HD, suggesting that axons represent an early and potentially critical target for mhtt toxicity.

  8. The roles of callose, elicitors and ethylene in thigmomorphogenesis and gravitropism

    NASA Technical Reports Server (NTRS)

    Jaffe, M. J.

    1984-01-01

    A correlation (both temporal and through the inhibitor, 2-deoxy-D-glucose) of callose deposition and ethylene evolution in mechanically perturbed (MP) bean or pine stems or in gravitationally stimulated corn shoots was demonstrated. It was suggested that the callose, which is deposited on the inside of the cell wall, and adjacent to the plasma membrane causes, in some way, the ethylene production. A hypothesis explaining the mechanism is discussed which states that there is a chemical activation of the enzyme system by the callose which is being deposited in apposition with it. Experimental data supporting the hypothesis are presented.

  9. Efferent inhibition of carotid body chemoreception in chronically hypoxic cats.

    PubMed

    Lahiri, S; Smatresk, N; Pokorski, M; Barnard, P; Mokashi, A

    1983-11-01

    The effects of chronic hypoxia on carotid chemoreceptor afferent activity before and after sectioning the carotid sinus nerves (CSN) were studied in cats exposed to 10% O2 for 21-49 days in a chamber at sea level. For comparison, chronically normoxic cats at sea level were also studied. The cats were anesthetized, paucifiber preparation for the measurement of carotid chemosensory activity from a small slip of CSN was made, and their steady-state responses to 4-5 levels of arterial pressure of O2 (PaO2) at a constant PaCO2 and to 3-4 levels of PaCO2 in hyperoxia were measured before and after sectioning the CSN. The chemosensory response to hypoxia in the cats with intact CSN after chronic exposure to hypoxia was not reduced relative to the cats that breathed room air at sea level. Sectioning the CSN significantly augmented the chemosensory responses to hypoxia in all the chronically hypoxic but not significantly in the normoxic cats. The responses to moderate hypercapnia during hyperoxia were not significantly changed by cutting the CSN in either group. We conclude that there is a significant CSN efferent inhibition of chemosensory activity due to chronic hypoxia in the cat. This implies that without the efferent inhibition the hypoxic chemosensitivity is increased by chronic hypoxia.

  10. 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. © 2015 Wiley Periodicals, Inc.

  11. 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

  12. Behavioural indexes of callosal functioning in Williams syndrome.

    PubMed

    Santos, Andreia; Rondan, Cécilie; Mancini, Josette; Deruelle, Christine

    2007-09-01

    Williams syndrome (WS) is a neurogenetic disorder that stems from a microdeletion on chromosome 7. Recent anatomical studies have found evidence for corpus callosum abnormalities in WS. However, to date, the impact of these structural differences on callosal functionality remains unclear. The aim of the present study was to investigate interhemispheric communication and hemispheric asymmetry in individuals with WS relative to mental age-matched controls. This was assessed using bilateral and unilateral presentations of visual stimuli in a picture-naming task. Results found both groups to exhibit a bilateral field advantage and a left visual advantage on unilateral presentations. However, while a significant performance increase with age was found for controls, no such correlation was found for individuals with WS. Taken together, these findings suggest that despite some evidence for an atypical developmental pathway in WS, both interhemispheric communication and hemispheric asymmetry are functionally intact in this population.

  13. Right unilateral jargonagraphia as a symptom of callosal disconnection.

    PubMed

    Ihori, Nami; Murayama, Junko; Mimura, Masaru; Miyazawa, Yumi; Kawamura, Mitsuru

    2006-01-01

    We report the case of a right-handed patient who exhibited right unilateral jargonagraphia after a traumatic callosal hemorrhage. The lesions involved the entire corpus callosum, except for the lower part of the genu and the splenium. The patient's right unilateral jargonagraphia was characterized by neologisms and perseveration in kanji and kana, and was more prominent in kana than kanji. The jargonagraphia was similar to that observed in crossed aphasia, except that agraphia occurred only with the right hand. The patient also showed right unilateral tactile anomia and right tactile alexia, along with right-ear extinction on a dichotic listening test for verbal stimuli, which suggested that language function was lateralized to the right hemisphere. Since this patient had learned to write with his right hand, kinesthetic images of characters were thought to be formed and stored dominantly in the left hemisphere. We suggest that the callosal lesions disturbed the interhemispheric transfer of information for the dual-route procedures for writing in the right hemisphere, allowing the kinesthetic images of characters stored in the left hemisphere to be processed freely, resulting in the right unilateral jargonagraphia. At least two factors seem to explain that kana was more defective than kanji. First, writing in kana, which is assumed to be processed mainly via a sub-word phoneme to grapheme conversion route, might depend more strongly on lateralized linguistic processing than writing in kanji. Second, kanji, which represent meaning as well as phonology, with much more complicated graphic patterns than kana, are assumed to be processed in both hemispheres.

  14. Structure and function of the corpus callosum in schizophrenia: What's the connection?

    PubMed

    David, A; Minne, C; Jones, P; Harvey, I; Ron, M

    1995-01-01

    Tests of both structure and function of the corpus callosum have revealed abnormalities in schizophrenic patients. One such functional test employed lateralised Stroop stimuli presented tachistoscopically, to measure the transfer of interference and facilitation between the cerebral hemispheres. An attempt was made to relate indices of callosal transfer to clinical and demographic variables, including family history, as well as to indices of brain morphology. The latter included ventricle: brain ratio (VBR) measured by computed tomography (CT) scanning on 31 DSMIII schizophrenics, and the cross-sectional area of the corpus callosum from magnetic resonance imaging (MRI), obtained from 20 of these patients. VBR did not relate to functional measures; however, anterior callosal area correlated with indices of callosal connectivity. Patients with auditory hallucinations had smaller anterior callosal areas and tended to show less connectivity. The results show links between functional and structural measures of the corpus callosum, but their precise nature remains unclear.

  15. Effect of human auditory efferent feedback on cochlear gain and compression.

    PubMed

    Yasin, Ifat; Drga, Vit; Plack, Christopher J

    2014-11-12

    The mammalian auditory system includes a brainstem-mediated efferent pathway from the superior olivary complex by way of the medial olivocochlear system, which reduces the cochlear response to sound (Warr and Guinan, 1979; Liberman et al., 1996). The human medial olivocochlear response has an onset delay of between 25 and 40 ms and rise and decay constants in the region of 280 and 160 ms, respectively (Backus and Guinan, 2006). Physiological studies with nonhuman mammals indicate that onset and decay characteristics of efferent activation are dependent on the temporal and level characteristics of the auditory stimulus (Bacon and Smith, 1991; Guinan and Stankovic, 1996). This study uses a novel psychoacoustical masking technique using a precursor sound to obtain a measure of the efferent effect in humans. This technique avoids confounds currently associated with other psychoacoustical measures. Both temporal and level dependency of the efferent effect was measured, providing a comprehensive measure of the effect of human auditory efferents on cochlear gain and compression. Results indicate that a precursor (>20 dB SPL) induced efferent activation, resulting in a decrease in both maximum gain and maximum compression, with linearization of the compressive function for input sound levels between 50 and 70 dB SPL. Estimated gain decreased as precursor level increased, and increased as the silent interval between the precursor and combined masker-signal stimulus increased, consistent with a decay of the efferent effect. Human auditory efferent activation linearizes the cochlear response for mid-level sounds while reducing maximum gain.

  16. Clinical features and associated abnormalities in children and adolescents with corpus callosal anomalies.

    PubMed

    Kim, Young Uhk; Park, Eun Sook; Jung, Soojin; Suh, Miri; Choi, Hyo Seon; Rha, Dong-Wook

    2014-02-01

    Callosal anomalies are frequently associated with other central nervous system (CNS) and/or somatic anomalies. We retrospectively analyzed the clinical features of corpus callosal agenesis/hypoplasia accompanying other CNS and/or somatic anomalies. We reviewed the imaging and clinical information of patients who underwent brain magnetic resonance imaging in our hospital, between 2005 and 2012. Callosal anomalies were isolated in 13 patients, accompanied by other CNS anomalies in 10 patients, associated with only non-CNS somatic anomalies in four patients, and with both CNS and non-CNS abnormalities in four patients. Out of 31 patients, four developed normally, without impairments in motor or cognitive functions. Five of nine patients with cerebral palsy were accompanied by other CNS and/or somatic anomalies, and showed worse Gross Motor Function Classification System scores, compared with the other four patients with isolated callosal anomaly. In addition, patients with other CNS anomalies also had a higher seizure risk.

  17. Language lateralization in a patient with temporal lobe epilepsy and callosal agenesis.

    PubMed

    Alsaadi, Taoufik; Shahrour, Tarek M

    2015-01-01

    The corpus callosum has been proposed as a mechanism of interhemispheric inhibition that allows language dominance to develop [1]. Callosal agenesis or dysgenesis provides a test of this hypothesis, as patients lacking a normal corpus callosum should also lack normal language lateralization [2]. We report pre- and postoperative functional magnetic resonance imaging (fMRI) and neuropsychological testing in a patient with partial callosal agenesis who underwent a right temporal lobectomy for medically refractory seizures.

  18. Elevated early callose deposition results in complete penetration resistance to powdery mildew in Arabidopsis.

    PubMed

    Ellinger, Dorothea; Naumann, Marcel; Falter, Christian; Zwikowics, Claudia; Jamrow, Torsten; Manisseri, Chithra; Somerville, Shauna C; Voigt, Christian A

    2013-03-01

    A common response by plants to fungal attack is deposition of callose, a (1,3)-β-glucan polymer, in the form of cell wall thickenings called papillae, at site of wall penetration. While it has been generally believed that the papillae provide a structural barrier to slow fungal penetration, this idea has been challenged in recent studies of Arabidopsis (Arabidopsis thaliana), where fungal resistance was found to be independent of callose deposition. To the contrary, we show that callose can strongly support penetration resistance when deposited in elevated amounts at early time points of infection. We generated transgenic Arabidopsis lines that express POWDERY MILDEW RESISTANT4 (PMR4), which encodes a stress-induced callose synthase, under the control of the constitutive 35S promoter. In these lines, we detected callose synthase activity that was four times higher than that in wild-type plants 6 h post inoculation with the virulent powdery mildew Golovinomyces cichoracearum. The callose synthase activity was correlated with enlarged callose deposits and the focal accumulation of green fluorescent protein-tagged PMR4 at sites of attempted fungal penetration. We observed similar results from infection studies with the nonadapted powdery mildew Blumeria graminis f. sp. hordei. Haustoria formation was prevented in resistant transgenic lines during both types of powdery mildew infection, and neither the salicylic acid-dependent nor jasmonate-dependent pathways were induced. We present a schematic model that highlights the differences in callose deposition between the resistant transgenic lines and the susceptible wild-type plants during compatible and incompatible interactions between Arabidopsis and powdery mildew.

  19. Improved Executive Function and Callosal White Matter Microstructure after Rhythm Exercise in Huntington's Disease.

    PubMed

    Metzler-Baddeley, Claudia; Cantera, Jaime; Coulthard, Elizabeth; Rosser, Anne; Jones, Derek K; Baddeley, Roland J

    2014-01-01

    Huntington's disease (HD) is an autosominal dominant neurodegenerative condition that leads to progressive loss of motor and cognitive functions. Early symptoms in HD include subtle executive dysfunction related to white and grey matter loss in cortico-striatal-thalamic loops. There is no cure for HD and hence a significant need for early intervention with the potential to delay the clinical onset of the disease. The objective of the present pilot study was to devise a novel behavioural intervention involving drumming and rhythm exercises that targets early dysexecutive problems, such as difficulties in sequence and reversal learning, response speed, timing, and dual tasking. One preclinical person and nine people with early to advanced stages of HD were recruited of whom five completed the two months intervention. The effects of rhythm exercise on executive function, basal ganglia volume, and white matter microstructure in the anterior corpus callosum, the anterior thalamic radiation, and the cortico-spinal tract were assessed post- relative to pre-training. After two months training, improvements in executive function and changes in white matter microstructure, notably in the genu of the corpus callosum that connects prefrontal cortices of both hemispheres, were observed. No changes in basal ganglia volume were present. This pilot study provides novel preliminary evidence that carefully targeted behavioural stimulation in HD can result in cognitive enhancement and improvements in callosal white matter microstructure.

  20. Callosal degeneration topographically correlated with cognitive function in amnestic mild cognitive impairment and Alzheimer's disease dementia.

    PubMed

    Wang, Pei-Ning; Chou, Kun-Hsien; Chang, Ni-Jung; Lin, Ker-Neng; Chen, Wei-Ta; Lan, Gong-Yau; Lin, Ching-Po; Lirng, Jiing-Feng

    2014-04-01

    Degeneration of the corpus callosum (CC) is evident in the pathogenesis of Alzheimer's disease (AD). However, the correlation of microstructural damage in the CC on the cognitive performance of patients with amnestic mild cognitive impairment (aMCI) and AD dementia is undetermined. We enrolled 26 normal controls, 24 patients with AD dementia, and 40 single-domain aMCI patients with at least grade 1 hippocampal atrophy and isolated memory impairment. Diffusion tensor imaging (DTI) with fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (DA), and radial diffusivity (DR) were measured. The entire CC was parcellated based on fiber trajectories to specific cortical Brodmann areas using a probabilistic tractography method. The relationship between the DTI measures in the subregions of the CC and cognitive performance was examined. Although the callosal degeneration in the patients with aMCI was less extended than in the patients with AD dementia, degeneration was already exhibited in several subregions of the CC at the aMCI stage. Scores of various neuropsychological tests were correlated to the severity of microstructural changes in the subregional CC connecting to functionally corresponding cortical regions. Our results confirm that CC degeneration is noticeable as early as the aMCI stage of AD and the disconnection of the CC subregional fibers to the corresponding Brodmann areas has an apparent impact on the related cognitive performance. Copyright © 2013 Wiley Periodicals, Inc.

  1. The brainstem efferent acoustic chiasm in pigmented and albino rats.

    PubMed

    Reuss, Stefan; Closhen-Gabrisch, Stefanie; Closhen, Christina

    2016-02-01

    The present study examined whether structural peculiarities in the brain-efferent pathway to the organ of Corti may underlie functional differences in hearing between pigmented and albino individuals of the same mammalian species. Pigmented Brown-Norway rats and albino Wistar rats received unilateral injections of an aqueous solution of the retrograde neuronal tracer Fluorogold (FG) into the scala tympani of the cochlea to identify olivocochlear neurons (OCN) in the brainstem superior olivary complex. After five days, brains were perfusion-fixed and brainstem sections were cut and analyzed with respect to retrogradely labeled neurons. Intrinsic neurons of the lateral system were located exclusively in the ipsilateral lateral superior olive (LSO) in both groups. Shell neurons surrounding the LSO and in periolivary regions, which made up only 5-8% of all OCN, were more often contralaterally located in albino than in pigmented animals. A striking difference was observed in the laterality of neurons of the medial olivocochlear (MOC) system, which provided more than one third of all OCN. These neurons, located in the rostral periolivary region and in the ventral nucleus of the trapezoid body, were observed contralateral to 45% in pigmented and to 68% in albino animals. Our study, the first to compare the origin of the olivocochlear bundle in pigmented and albino rats, provides evidence for differences in the crossing pattern of the olivocochlear pathway. These were found predominantly in the MOC system providing the direct efferent innervation of cochlear outer hair cells. Our findings may account for the alterations in auditory perception observed in albino mammals including man.

  2. Medial olivocochlear efferent reflex inhibition of human cochlear nerve responses.

    PubMed

    Lichtenhan, J T; Wilson, U S; Hancock, K E; Guinan, J J

    2016-03-01

    Inhibition of cochlear amplifier gain by the medial olivocochlear (MOC) efferent system has several putative roles: aiding listening in noise, protection against damage from acoustic overexposure, and slowing age-induced hearing loss. The human MOC reflex has been studied almost exclusively by measuring changes in otoacoustic emissions. However, to help understand how the MOC system influences what we hear, it is important to have measurements of the MOC effect on the total output of the organ of Corti, i.e., on cochlear nerve responses that couple sounds to the brain. In this work we measured the inhibition produced by the MOC reflex on the amplitude of cochlear nerve compound action potentials (CAPs) in response to moderate level (52-60 dB peSPL) clicks from five, young, normal hearing, awake, alert, human adults. MOC activity was elicited by 65 dB SPL, contralateral broadband noise (CAS). Using tympanic membrane electrodes, approximately 10 h of data collection were needed from each subject to yield reliable measurements of the MOC reflex inhibition on CAP amplitudes from one click level. The CAS produced a 16% reduction of CAP amplitude, equivalent to a 1.98 dB effective attenuation (averaged over five subjects). Based on previous reports of efferent effects as functions of level and frequency, it is possible that much larger effective attenuations would be observed at lower sound levels or with clicks of higher frequency content. For a preliminary comparison, we also measured MOC reflex inhibition of DPOAEs evoked from the same ears with f2's near 4 kHz. The resulting effective attenuations on DPOAEs were, on average, less than half the effective attenuations on CAPs.

  3. Central efferent pathways for cold-defensive and febrile shivering

    PubMed Central

    Nakamura, Kazuhiro; Morrison, Shaun F

    2011-01-01

    Abstract Shivering is a remarkable somatomotor thermogenic response that is controlled by brain mechanisms. We recorded EMGs in anaesthetized rats to elucidate the central neural circuitry for shivering and identified several brain regions whose thermoregulatory neurons comprise the efferent pathway driving shivering responses to skin cooling and pyrogenic stimulation. We simultaneously monitored parameters from sympathetic effectors: brown adipose tissue (BAT) temperature for non-shivering thermogenesis and arterial pressure and heart rate for cardiovascular responses. Acute skin cooling consistently increased EMG, BAT temperature and heart rate and these responses were eliminated by inhibition of neurons in the median preoptic nucleus (MnPO) with nanoinjection of muscimol. Stimulation of the MnPO evoked shivering, BAT thermogenesis and tachycardia, which were all reversed by antagonizing GABAA receptors in the medial preoptic area (MPO). Inhibition of neurons in the dorsomedial hypothalamus (DMH) or rostral raphe pallidus nucleus (rRPa) with muscimol or activation of 5-HT1A receptors in the rRPa with 8-OH-DPAT eliminated the shivering, BAT thermogenic, tachycardic and pressor responses evoked by skin cooling or by nanoinjection of prostaglandin (PG) E2, a pyrogenic mediator, into the MPO. These data are summarized with a schematic model in which the shivering as well as the sympathetic responses for cold defence and fever are driven by descending excitatory signalling through the DMH and the rRPa, which is under a tonic inhibitory control from a local circuit in the preoptic area. These results provide the interesting notion that, under the demand for increasing levels of heat production, parallel central efferent pathways control the somatic and sympathetic motor systems to drive thermogenesis. PMID:21610139

  4. 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.

  5. Differences in early callose deposition during adapted and non-adapted powdery mildew infection of resistant Arabidopsis lines.

    PubMed

    Naumann, Marcel; Somerville, Shauna; Voigt, Christian

    2013-06-01

    The deposition of callose, a (1,3)-β-glucan cell wall polymer, can play an essential role in the defense response to invading pathogens. We could recently show that Arabidopsis thaliana lines with an overexpression of the callose synthase gene PMR4 gained complete penetration resistance to the adapted powdery mildew Golovinomyces cichoracearum and the non-adapted powdery mildew Blumeria graminis f. sp hordei. The penetration resistance is based on the transport of the callose synthase PMR4 to the site of attempted fungal penetration and the subsequent formation of enlarged callose deposits. The deposits differed in their total diameter comparing both types of powdery mildew infection. In this study, further characterization of these callose deposits revealed that size differences were especially pronounced in the core region of the deposits. This suggests that specific, pathogen-dependent factors exist, which might regulate callose synthase transport to the core region of forming deposits.

  6. 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.

  7. 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

  8. Efferent projections of the septum in the Tegu lizard, Tupinambis nigropunctatus.

    PubMed

    Sligar, C M; Voneida, T J

    1981-09-01

    A H3 proline or H3 leucine mixture was injected into the septal region of the Tegu lizard in order to determine its efferent projections. The brains were processed according to standard autoradiographic technique and counterstained with cresyl violet. Septal projections were limited to either telencephalic or diencephalic areas. Intratelencephalic projections consisted of efferents to medial pallium, nucleus accumbens, bed nucleus of the anterior commissure, preoptic area and septum itself. Fibers entering the diencephalon projected to medial habenular nucleus, dorsomedial thalamic nucleus, dorsolateral thalamic area, periventricular nucleus of the hypothalamus, lateral hypothalamic area and mammillary nucleus. The results are discussed in relation to the efferent projections of the septum in other vertebrates.

  9. 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

  10. Sound lateralization in subjects with callosotomy, callosal agenesis, or hemispherectomy.

    PubMed

    Hausmann, Markus; Corballis, Michael C; Fabri, Mara; Paggi, Aldo; Lewald, Jörg

    2005-10-01

    The question of whether there is a right-hemisphere dominance in the processing of auditory spatial information in human cortex as well as the role of the corpus callosum in spatial hearing functions is still a matter of debate. Here, we approached this issue by investigating two late-callosotomized subjects and one subject with agenesis of the corpus callosum, using a task of sound lateralization with variable interaural time differences. For comparison, three subjects with left or right hemispherectomy were also tested by employing identical methods. Besides a significant reduction in their acuity, subjects with total or partial section of the corpus callosum exhibited a considerable leftward bias of sound lateralization compared to normal controls. No such bias was found in the subject with callosal agenesis, but merely a marginal reduction of general acuity. Also, one subject with complete resection of the left cerebral cortex showed virtually normal performance, whereas another subject with left hemispherectomy and one subject with right hemispherectomy exhibited severe deficits, with almost total loss of sound-lateralization ability. The results obtained in subjects with callosotomy indicate that the integrity of the corpus callosum is not indispensable for preservation of sound-lateralization ability. On the other hand, transcallosal interhemispheric transfer of auditory information obviously plays a significant role in spatial hearing functions that depend on binaural cues. Moreover, these data are compatible with the general view of a dominance of the right cortical hemisphere in auditory space perception.

  11. Similar synapse elimination motifs at successive relays in the same efferent pathway during development in mice

    PubMed Central

    Sheu, Shu-Hsien; Tapia, Juan Carlos; Tsuriel, Shlomo; Lichtman, Jeff W

    2017-01-01

    In many parts of the nervous system, signals pass across multiple synaptic relays on their way to a destination, but little is known about how these relays form and the function they serve. To get some insight into this question we ask how the connectivity patterns are organized at two successive synaptic relays in a simple, cholinergic efferent pathway. We found that the organization at successive relays in the parasympathetic nervous system strongly resemble each other despite the different embryological origin and physiological properties of the pre- and postsynaptic cells. Additionally, we found a similar developmental synaptic pruning and elaboration strategy is used at both sites to generate their adult organizations. The striking parallels in adult innervation and developmental mechanisms at the relays argue that a general strategy is in operation. We discuss why from a functional standpoint this structural organization may amplify central signals while at the same time maintaining positional targeting. DOI: http://dx.doi.org/10.7554/eLife.23193.001 PMID:28157072

  12. 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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. [Frequency, morphology, pathogenesis and complications of silicotic callosities (phthisis atra). A disappearing disease].

    PubMed

    Breining, H

    2003-03-01

    Over a period of approximately 30 years we have compared the frequency of Miner's phthisis in the coal mining areas of Aachen and the Ruhr area of Essen and have investigated a total of approximately 600 lungs with silicosis. In cases of silicosis grades II-III and III we found liquefaction in 36% of the callosities but in cases of silicosis I-II and II in only 4-7%. Liquefaction of callosities, or phthisis atra, was found slightly more often in the Ruhr area than in the area of Aachen. If the liquefied silicotic material is expectorated from the bronchial tubes, a cavern-like cavity develops in the lungs, which clinically can often not be differentiated from a tuberculotic cavern. Sometimes silicotic material is transported via the blood vessels and dust particles could often be found microscopically in the liver, spleen or kidneys. In one patient we found silicotic material coming from the bronchial veins with development of arterial embolisms in peripheral arteries of the extremities and brain. The pathogenesis of callosity liquefaction is a consequence of disruption of the blood supply to the surrounding areas of the callosities. In some cases blood vessels in the centre of the callosities are destroyed so that the patient dies after severe haemoptysis.

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

    PubMed

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

    2012-02-28

    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.

  15. Reviewing the Role of the Efferent Vestibular System in Motor and Vestibular Circuits

    PubMed Central

    Mathews, Miranda A.; Camp, Aaron J.; Murray, Andrew J.

    2017-01-01

    Efferent circuits within the nervous system carry nerve impulses from the central nervous system to sensory end organs. Vestibular efferents originate in the brainstem and terminate on hair cells and primary afferent fibers in the semicircular canals and otolith organs within the inner ear. The function of this efferent vestibular system (EVS) in vestibular and motor coordination though, has proven difficult to determine, and remains under debate. We consider current literature that implicate corollary discharge from the spinal cord through the efferent vestibular nucleus (EVN), and hint at a potential role in overall vestibular plasticity and compensation. Hypotheses range from differentiating between passive and active movements at the level of vestibular afferents, to EVS activation under specific behavioral and environmental contexts such as arousal, predation, and locomotion. In this review, we summarize current knowledge of EVS circuitry, its effects on vestibular hair cell and primary afferent activity, and discuss its potential functional roles. PMID:28824449

  16. Role of Nicotinic Acetylcholine Receptor on Efferent Inhibition in Cochlear Hair Cell

    PubMed Central

    2012-01-01

    The α9α10 nicotinic acetylcholine receptors (nAChRs) mediates efferent inhibition of hair cell function within the auditory sensory organ. Gating of the nAChRs leads to activation of calcium-dependent potassium channels to hyperpolarize the hair cell. In efferent system, main calcium providers to SK channel are nAChR and synaptic cistern, which contribution to efferent inhibition is different between avian and mammalian species. Calcium permeation is more effective in nAChRs of mammalian cochlea than avian cochlea, and mammalian calcium permeability of nAChRs is about 3 times more than avian hair cell. Thus, mammalian nAChRs is a main component of efferent inhibition in cochlear hair cell system. PMID:24653883

  17. Efferent and afferent evoked potentials in patients with adrenomyeloneuropathy.

    PubMed

    Matsumoto, Hideyuki; Hanajima, Ritsuko; Terao, Yasuo; Hamada, Masashi; Yugeta, Akihiro; Shirota, Yuichiro; Yuasa, Kaoru; Sato, Fumio; Matsukawa, Takashi; Takahashi, Yuji; Goto, Jun; Tsuji, Shoji; Ugawa, Yoshikazu

    2010-02-01

    This paper investigates efferent and afferent conductions of the central nervous system by various evoked potentials in patients with adrenomyeloneuropathy (AMN). Ten pure AMN patients without cerebral involvement were studied. Motor evoked potentials (MEPs), somatosensory evoked potentials (SEPs), auditory brainstem response (ABR), and pattern reversal full-field visual evoked potentials (VEPs) were recorded. For MEP recording, single-pulse or double-pulse magnetic brainstem stimulation (BST) was also performed. Abnormal MEP was observed in all ten patients, abnormal SEP in all ten, abnormal ABR in nine, and abnormal VEP in only one. Brainstem latency was measured in three of the seven patients with central motor conduction time (CMCT) prolongation. The cortical-brainstem conduction time was severely prolonged along the normal or mildly delayed brainstem-cervical conduction time in those three patients. The pattern of normal VEP and abnormal MEP, SEP, ABR is a clinically useful electrophysiological feature for the diagnosis. BST techniques are helpful to detect, functionally, intracranial corticospinal tract involvement, probably demyelination, in pure AMN patients. 2009 Elsevier B.V. All rights reserved.

  18. 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.

  19. 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.

  20. Auditory Efferents Facilitate Sound Localization in Noise in Humans

    PubMed Central

    Andéol, Guillaume; Guillaume, Anne; Micheyl, Christophe; Savel, Sophie; Pellieux, Lionel; Moulin, Annie

    2011-01-01

    The mammalian auditory system contains descending neural pathways, some of which project onto the cochlea via the medial olivocochlear (MOC) system. The function of this efferent auditory system is not entirely clear. Behavioral studies in animals with OC lesions suggest that the MOC serves to facilitate sound localization in noise. In the current work, noise-induced OC activity (the “OC reflex”) and sound-localization performance in noise were measured in normal-hearing humans. Consistent with earlier studies, both measures were found to vary substantially across individuals. Importantly, significant correlations were observed between OC reflex strength and the effect of noise on sound-localization performance; the stronger the OC reflex, the less marked the effect of noise. These results suggest that MOC activation by noise helps to counteract the detrimental effects of background noise on neural representations of direction-dependent spectral features, which are especially important for accurate localization in the up/down and front/back dimensions. PMID:21543605

  1. 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

  2. Exogenous cholecystokinin-8 reduces vagal efferent nerve activity in rats through CCKA receptors

    PubMed Central

    Bucinskaite, Violeta; Kurosawa, Mieko; Lundeberg, Thomas

    2000-01-01

    It has been proposed that the vagus nerve plays a role in mediating cholecystokinin-8 (CCK-8) effect on such gastric functions as motility, emptying and gastric acid secretion. To examine the contribution of the efferent pathways in realizing these effects, efferent mass activity in the ventral gastric vagal nerve in Sprague-Dawley rats was recorded.Intravenous infusion of CCK-8 (0.1–1 nmol) suppressed the efferent activity. The effect of CCK-8 was significantly reduced in animals with total subdiaphragmatic vagotomy in comparison to those with partial vagotomy.Intravenous infusion of CCKA receptor antagonist L-364,718 (1–100×10−6 g) blocked the response of vagal efferent activity to 0.1 nmol CCK-8, but the CCKB receptor antagonist L-365,260 (1–100×10−6 g) did not in the conditions of either partial or total vagotomy.Intracisternal infusion of L-364,718 (1×10−6 g) blocked the response of vagal efferent activity to 0.1 nmol CCK-8 i.v.Infusion of exogenous CCK-8 did not affect the activity of supradiaphragmatic vagal afferents.The results suggest that the effect of systemically administered CCK-8 on vagal efferent activity is mediated by both peripherally (subdiaphragmatically) and centrally localized CCKA receptors. PMID:10780970

  3. Assessing prenatal white matter connectivity in commissural agenesis.

    PubMed

    Kasprian, Gregor; Brugger, Peter C; Schöpf, Veronika; Mitter, Christian; Weber, Michael; Hainfellner, Johannes A; Prayer, Daniela

    2013-01-01

    Complete or partial agenesis of the corpus callosum are rather common developmental abnormalities, resulting in a wide spectrum of clinical neurodevelopmental deficits. Currently, a significant number of these cases are detected by prenatal sonography during second trimester screening examinations. However, major uncertainties about a detailed morphological diagnosis and the clinical significance do not allow accurate prenatal counselling. Here, we were able to demonstrate the 3D connectivity of aberrant commissural tracts in 16 cases with complete and four cases with partial callosal agenesis using the foetal magnetic resonance imaging techniques of diffusion tensor imaging and tractography in utero and in vivo between gestational weeks 20 and 37. The 'misguided' pre-myelinated callosal axons that represent the bundle of Probst were non-invasively visualized, and they showed a degree of structural integrity similar to that of the callosal pathways of age-matched foetuses without cerebral pathologies. In two foetuses, we were able to prove, by post-mortem histology, that diffusion tensor imaging allows the depiction of the bundle of Probst, even during early stages of pre-myelination at 20 and 22 gestational weeks. In cases with partial callosal agenesis, an aberrant sigmoid-shaped bundle was prenatally depicted, confirming the findings of heterotopic interhemispheric connectivity in adults with partial callosal agenesis. In addition to the corpus callosum, other white matter pathways were also involved, including somatosensory and motor pathways that showed significantly higher fractional anisotropy values in cases with callosal agenesis compared with control subjects. A detailed prenatal assessment of abnormal white matter connectivity in cases of midline anomalies will help to explain and understand the clinical heterogeneity in these cases, taking future foetal neurological counselling strategies to a new level.

  4. Prognosis of painful plantar callosity after hallux valgus correction without lesser metatarsal osteotomy.

    PubMed

    Lee, Keun-Bae; Park, Ju-Kwon; Park, Young-Hoon; Seo, Hyung-Yeon; Kim, Myung-Sun

    2009-11-01

    Painful plantar callosities under lesser metatarsal heads are commonly associated with hallux valgus. The purpose of the present study was to evaluate the prognosis of painful plantar callosities after hallux valgus correction without lesser metatarsal osteotomy in hallux valgus deformity. Between September 2004 and June 2007, 31 patients (40 feet) underwent proximal chevron first metatarsal osteotomy with a distal soft tissue procedure, with preoperatively painful plantar callosities under lesser metatarsal heads. Clinical results were evaluated using a visual analogue scale (VAS), the American Orthopaedic Foot and Ankle Society (AOFAS) hallux-metatarsophalangeal interphalangeal scales, and a modified 70-point clinical scale. Radiographic evaluations included hallux valgus angle and intermetatarsal angle. Thirty-two (80%) of the 40 feet had no pain and callosity and 5 (12.5%) had no pain but residual plantar callosities, and 3 (7.5%) were not improved at final evaluation. The mean VAS and AOFAS scores were improved from 7.8 +/- 1.6 to 1.9 +/- 1.5 points and from 53.8 +/- 14.2 to 92.6 +/- 15.3 points, respectively. In terms of the 70-point clinical scale, overall clinical results were good in 34 feet and fair in 6. The mean hallux valgus and intermetatarsal angles were improved from 36.6 +/- 6.2 to 12.5 +/- 5.9 degrees and from 17.5 +/- 3.9 to 8.6 +/- 3.5 degrees, respectively. Painful plantar callosities under the lesser metatarsals in patients with hallux valgus deformity can be improved by hallux valgus correction alone without lesser metatarsal osteotomy.

  5. Interhemispheric Lipoma, Callosal Anomaly, and Malformations of Cortical Development: A Case Series.

    PubMed

    Niwa, Tetsu; de Vries, Linda S; Manten, Gwendolyn T R; Lequin, Maarten; Cuppen, Inge; Shibasaki, Jun; Aida, Noriko

    2016-04-01

    Intracranial lipomas are rare congenital malformations. The most common type of intracranial lipoma is the interhemispheric lipoma, which is frequently associated with callosal anomalies such as hypogenesis or agenesis of the corpus callosum. In contrast, interhemispheric lipomas are less often accompanied with malformations of cortical development (MCD). We report magnetic resonance imaging findings of three infants with an interhemispheric lipoma, associated with a callosal anomaly, and MCD: two infants with nodular interhemispheric lipoma, agenesis of the corpus callosum, and polymicrogyria, and one infant with interhemispheric curvilinear lipoma, hypoplasia of the corpus callosum, and heterotopias. An association was suggested regarding the occurrence of these malformations.

  6. Pharmacology of Acetylcholine-Mediated Cell Signaling in the Lateral Line Organ Following Efferent Stimulation

    PubMed Central

    Dawkins, Rosie; Keller, Sarah L.; Sewell, William F.

    2007-01-01

    Cholinergic efferent fibers modify hair cell responses to mechanical stimulation. It is hypothesized that calcium entering the hair cell through a nicotinic receptor activates a small-conductance (SK), calcium-activated potassium channel to hyperpolarize the hair cell. The calcium signal may be amplified by calcium-induced calcium release from the synaptic cisternae. Pharmacological tests of these ideas in the intact cochlea have been technically difficult because of the complex and fragile structure of the mammalian inner ear. We turned to the Xenopus laevis lateral line organ, whose simplicity and accessibility make it a model for understanding hair cell organ function in a relatively intact system. Drugs were applied to the inner surface of the skin while monitoring the effects of efferent stimulation on afferent fiber discharge rate. Efferent effects were blocked by antagonists of SK channels including apamin (EC50 = 0.5 μM) and dequalinium (EC50 = 12 μM). The effect of apamin was not enhanced by co-administration of phenylmethylsulfonyl fluoride, a proteolysis inhibitor. Efferent effects were attenuated by ryanodine, an agent that can interfere with calcium-induced calcium release, although relatively high (mM) concentrations of ryanodine were required. Fluorescent cationic styryl dyes, 4-di-2-asp and fm 1– 43, blocked efferent effects, although it was not possible to observe specific entry of the dye into the base of hair cells. These pharmacological findings in the Xenopus lateral line organ support the hypothesis that effects of efferent stimulation are mediated by calcium entry through the nicotinic receptor via activation of SK channels and suggest the generality of this mechanism in meditating cholinergic efferent effects. PMID:15615825

  7. Changes in the parameters of gait after a mechanical debridement of a plantar callosities.

    PubMed

    Gijon-Nogueron, Gabriel; Garcia-Paya, Irene; Ortega-Avila, Ana Belen; Paez-Moguer, Joaquin; Cervera-Marin, Jose Antonio

    2015-02-01

    Plantar callosities are a common cause of pain in the forefoot and also a cause of alterations in plantar pressure. Mechanical debridement with a scalpel can relieve pain and increase functional capacity. The aim of the study was to analyse if debridement of plantar callosities and corns modify walking. Thirty four patients with plantar foot pain due to callosities and corns, and up to 5 in the visual analogical scale (VAS) of pain, (20 women, age 29 ± 11.57 years) were analysed by taking into account the changes of their gait. The outcome measurement was the VAS scale and the Win-track system, cycle of the gait(milliseconds), angle(degrees), cadence(number/minutes) and step(centimetres) were measured, 24 h before and after the debridement with a scalpel. There were significant differences in foot pain (mean 67.7, p < 0.001) but there were no significant differences in measures of gait variables before the debridement of the callosities, and 24 h after the procedure, being all those above 0.05. Our study shows that the debridement with scalpel does not change the variables of the gait 24 h after the procedure. Copyright © 2015 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

  8. The callosal dilemma: explaining diaschisis in the context of hemispheric rivalry via a neural network model.

    PubMed

    Reggia, J A; Goodall, S M; Shkuro, Y; Glezer, M

    2001-07-01

    It is often suggested that a major factor in diaschisis is the loss of transcallosal excitation to the intact hemisphere from the lesioned one. However, there is long-standing disagreement in the broader experimental literature about whether transcallosal interhemispheric influences in the human brain are primarily excitatory or inhibitory. Some experimental data are apparently better explained by assuming inhibitory callosal influences. Past neural network models attempting to explore this issue have encountered the same dilemma: in intact models, inhibitory callosal influences best explain strong cerebral lateralization like that occurring with language, but in lesioned models, excitatory callosal influences best explain experimentally observed hemispheric activation patterns following brain damage. We have now developed a single neural network model that can account for both types of data, i.e., both diaschisis and strong hemisphere specialization in the normal brain, by combining excitatory callosal influences with subcortical cross-midline inhibitory interactions. The results suggest that subcortical competitive processes may be a more important factor in cerebral specialization than is generally recognized.

  9. Magnetic resonance imaging and histological studies of corpus callosal and hippocampal abnormalities linked to doublecortin deficiency.

    PubMed

    Kappeler, Caroline; Dhenain, Marc; Phan Dinh Tuy, Françoise; Saillour, Yoann; Marty, Serge; Fallet-Bianco, Catherine; Souville, Isabelle; Souil, Evelyne; Pinard, Jean-Marc; Meyer, Gundela; Encha-Razavi, Ferechté; Volk, Andreas; Beldjord, Cherif; Chelly, Jamel; Francis, Fiona

    2007-01-10

    Mutated doublecortin (DCX) gives rise to severe abnormalities in human cortical development. Adult Dcx knockout mice show no major neocortical defects but do have a disorganized hippocampus. We report here the developmental basis of these hippocampal abnormalities. A heterotopic band of neurons was identified starting at E17.5 in the CA3 region and progressing throughout the CA1 region by E18.5. At neonatal stages, the CA1 heterotopic band was reduced, but the CA3 band remained unchanged, continuing into adulthood. Thus, in mouse, migration of CA3 neurons is arrested during development, whereas CA1 cell migration is retarded. On the Sv129Pas background, magnetic resonance imaging (MRI) also suggested abnormal dorsal hippocampal morphology, displaced laterally and sometimes rostrally and associated with medial brain structure abnormalities. MRI and cryosectioning showed agenesis of the corpus callosum in Dcx knockout mice on this background and an intermediate, partial agenesis in heterozygote mice. Wild-type littermates showed no callosal abnormalities. Hippocampal and corpus callosal abnormalities were also characterized in DCX-mutated human patients. Severe hippocampal hypoplasia was identified along with variable corpus callosal defects ranging from total agenesis to an abnormally thick or thin callosum. Our data in the mouse, identifying roles for Dcx in hippocampal and corpus callosal development, might suggest intrinsic roles for human DCX in the development of these structures.

  10. 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. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Bilaterally-projecting efferent neurones to the basilar papilla in the barn owl and the chicken.

    PubMed

    Raabe, Tobias; Köppl, Christine

    2003-10-03

    The efferent innervation of the auditory basilar papilla of birds and mammals is provided by a dedicated population of brainstem neurones that are separate from those supplying the vestibular organs. This study addresses the question whether a population of bilaterally-projecting efferents, contacting hair cells in both basilar papillae, is consistently present in birds. The chicken and the barn owl were chosen, two species where the total number of efferents was already known and which represent two extremes of an auditory generalist and an auditory specialist, respectively. Fluorogold and Choleratoxin, two potent retrograde tracers, were injected into one cochlear duct each of all individuals. Labelled neurones were subsequently identified in the brainstem using standard fluorescence techniques. A small proportion (up to 2% of the total population) of double-labelled cells was found in both species. The great majority of those double-labelled neurones could be assigned to the ventrolateral group of efferents, which has previously been shown to project exclusively to the auditory basilar papilla. Thus, in birds, like in mammals, a small subgroup of auditory efferents innervates both basilar papillae.

  12. 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

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

    PubMed

    Herburger, Klaus; Holzinger, Andreas

    2015-11-01

    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.

  14. 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

  15. 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

    2016-06-03

    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.

  16. Efferent connections of the orbitofrontal cortex in the marmoset (Saguinus oedipus).

    PubMed

    Leichnetz, G R; Astruc, J

    1975-02-07

    Unilateral partial ablations were made in the orbitofrontal cortex of 4 adult marmosets (Saguinus oedipus) and fiber degeneration was traced using the Nauta-Gygax and Fink-Heimer selective silver impregnation techniques. Corticocortical projections were found to the ipsilateral convexity and medial aspect of the frontal lobe and to the homologous orbitofrontal areas of the contralateral hemisphere. Fiber degeneration was followed through the uncinate fascicle to the temporal and insular cortices, and caudally into the rostrolateral entorhinal cortex. Other fibers joined the cingulum bundle and terminated throughout the cingulate cortex. Subcortical projections were observed to the lateral and basal amygdaloid nuclei, caudate head, ventrolateral putamen and ventral claustrum. The lateral preoptic and hypothalamic areas received a small number of fibers, as did the intralaminar and reticular thalamic nuclei. The dorsomedial nucleus of the thalamus was recipient of a large group of fibers which followed the ventral internal capsule and joined the inferior thalamic peduncle to terminate there. Preterminal debris appeared heaviest in the dorsomedial thalamic nucleus, pars magnocellularis (MDmc) in more caudal orbital lesions. A subthalamic projection to field H of Forel was observed. A small number of fibers terminated in the lateral midbrain tegmentum, but no appreciable fiber degeneration was observed more caudally than the midbrain. These results are compared in some areas to findings in the rhesus monkey. The possibility of a topical organization in the orbital cortical and thalamic projections is discussed.

  17. Autoradiographic study of the efferent connections of the entorhinal cortex in the rat

    SciTech Connect

    Wyss, J.M.

    1981-07-10

    The major findings can be summarized as follows. Whereas the projection of the lateral entorhinal area (LEA) to the dentate gyrus is broad in its longitudinal extent, the medial entorhinal area (MEA), and especially the ventral portion of this zone, projects in a more lamellar fashion. In the transverse plane the LEA preferentially projects to the inner (dorsal) blade of the dentate gyrus, while the MEA innervates both blades equally. Within the radial dimension, the entorhinal cortex projects to the dentate gyrus according to a medial to lateral gradient, with lateral portions of the LEA projecting along the pial surface and successively more medial portions of the entorhinal projecting closer to the granule cells. The commissural entorhinal to dentate projections are similar to the ipsilateral projections in location; however, they are considerably reduced in septotemporal extent and do not arise from cells in the ventral half of either LEA or the intermediate entorhinal area (IEA). The projection of the entorhinal cortex to Ammon's horn reflects the same longitudinal characteristics as the dentate projections. An alvear input which extends only to the pyramidal cells at the CA1-subicular junction was most noticeable at ventral hippocampal levels. The extrahippocampal projections arise predominantly from cells in the LEA and project forward along the angular bundle to the piriform and periamygdaloid cortices, as well as the endopiriform nucleus, the lateral, basolateral, and cortical amygdaloid nuclei, the nucleus of the lateral olfactory tract, the olfactory tubercle, the anterior olfactory nucleus, the taenia tecta, and the indusium griseum.

  18. Right-ear advantage drives the link between olivocochlear efferent 'antimasking' and speech-in-noise listening benefits.

    PubMed

    Bidelman, Gavin M; Bhagat, Shaum P

    2015-05-27

    The mammalian cochlea receives feedback from the brainstem medial olivocochlear (MOC) efferents, whose putative 'antimasking' function is to adjust cochlear amplification and enhance peripheral signal detection in adverse listening environments. Human studies have been inconsistent in demonstrating a clear connection between this corticofugal system and behavioral speech-in-noise (SIN) listening skills. To elucidate the role of brainstem efferent activity in SIN perception, we measured ear-specific contralateral suppression of transient-evoked otoacoustic emissions (OAEs), a proxy measure of MOC activation linked to auditory learning in noisy environments. We show that suppression of cochlear emissions is stronger with a more basal cochlear bias in the right ear compared with the left ear. Moreover, a strong negative correlation was observed between behavioral SIN performance and right-ear OAE suppression magnitudes, such that lower speech reception thresholds in noise were predicted by larger amounts of MOC-related activity. This brain-behavioral relation was not observed for left ear SIN perception. The rightward bias in contralateral MOC suppression of OAEs, coupled with the stronger association between physiological and perceptual measures, is consistent with left-hemisphere cerebral dominance for speech-language processing. We posit that corticofugal feedback from the left cerebral cortex through descending MOC projections sensitizes the right cochlea to signal-in-noise detection, facilitating figure-ground contrast and improving degraded speech analysis. Our findings demonstrate that SIN listening is at least partly driven by subcortical brain mechanisms; primitive stages of cochlear processing and brainstem MOC modulation of (right) inner ear mechanics play a critical role in dictating SIN understanding.

  19. Corpus callosal atrophy and associations with cognitive impairment in Parkinson disease.

    PubMed

    Goldman, Jennifer G; Bledsoe, Ian O; Merkitch, Doug; Dinh, Vy; Bernard, Bryan; Stebbins, Glenn T

    2017-03-28

    To investigate atrophy of the corpus callosum on MRI in Parkinson disease (PD) and its relationship to cognitive impairment. One hundred patients with PD and 24 healthy control participants underwent clinical and neuropsychological evaluations and structural MRI brain scans. Participants with PD were classified as cognitively normal (PD-NC; n = 28), having mild cognitive impairment (PD-MCI; n = 47), or having dementia (PDD; n = 25) by Movement Disorder Society criteria. Cognitive domain (attention/working memory, executive function, memory, language, visuospatial function) z scores were calculated. With the use of FreeSurfer image processing, volumes for total corpus callosum and its subsections (anterior, midanterior, central, midposterior, posterior) were computed and normalized by total intracranial volume. Callosal volumes were compared between participants with PD and controls and among PD cognitive groups, covarying for age, sex, and PD duration and with multiple comparison corrections. Regression analyses were performed to evaluate relationships between callosal volumes and performance in cognitive domains. Participants with PD had reduced corpus callosum volumes in midanterior and central regions compared to healthy controls. Participants with PDD demonstrated decreased callosal volumes involving multiple subsections spanning anterior to posterior compared to participants with PD-MCI and PD-NC. Regional callosal atrophy predicted cognitive domain performance such that central volumes were associated with the attention/working memory domain; midposterior volumes with executive function, language, and memory domains; and posterior volumes with memory and visuospatial domains. Notable volume loss occurs in the corpus callosum in PD, with specific neuroanatomic distributions in PDD and relationships of regional atrophy to different cognitive domains. Callosal volume loss may contribute to clinical manifestations of PD cognitive impairment. © 2017 American

  20. The link between callosal thickness and intelligence in healthy children and adolescents

    PubMed Central

    Luders, Eileen; Thompson, Paul M.; Narr, Katherine L.; Zamanyan, Alen; Chou, Yi-Yu; Gutman, Boris; Dinov, Ivo D.; Toga, Arthur W.

    2010-01-01

    The link between brain structure and intelligence is a well-investigated topic, but existing analyses have mainly focused on adult samples. Studies in healthy children and adolescents are rare, and normative data specifically addressing the association between corpus callosum morphology and intellectual abilities is quite limited. To advance this field of research, we mapped the correlations between standardized intelligence measures and callosal thickness based on high-resolution magnetic resonance imaging (MRI) data. Our large and well-matched sample included 200 normally developing subjects (100 males, 100 females) ranging from 6 to 17 years of age. Although the strongest correlations were negative and confined to the splenium, the strength and the direction of intelligence-callosal thickness associations varied considerably with respect to age and sex. While significant correlations in females were mainly positive, significant correlations in males were exclusively negative. However, only the negative correlations in the overall sample (i.e., males and females combined) remained significant when controlling for multiple comparisons. The observed negative correlations between callosal thickness and intelligence in children and adolescents contrast with the positive correlations typically reported in adult samples. However, negative correlations are in line with reports from other pediatric studies relating cognitive measures to other brain attributes such as cortical thickness, gray matter volume, and gray matter density. Altogether, these findings suggest that relationships between callosal morphology and cognition are highly dynamic during brain maturation. Sex effects on links between callosal thickness and intelligence during childhood and adolescence are present but appear rather weak in general. PMID:20932920

  1. 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

  2. Callosal Degradation in HIV-1 Infection Predicts Hierarchical Perception: A DTI study

    PubMed Central

    Müller-Oehring, Eva M.; Schulte, Tilman; Rosenbloom, Margaret J.; Pfefferbaum, Adolf; Sullivan, Edith V.

    2010-01-01

    HIV-1 infection affects white matter circuits linking frontal, parietal, and subcortical regions that subserve visuospatial attention processes. Normal perception requires the integration of details, preferentially processed in the left hemisphere, and the global composition of an object or scene, preferentially processed in the right hemisphere. We tested whether HIV-related callosal white matter degradation contributes to disruption of selective lateralized visuospatial and attention processes. A hierarchical letter target detection paradigm was devised, where large (global) letters were composed of small (local) letters. Participants were required to identify target letters among distractors presented at global, local, both or neither level. Attention was directed to one (global or local) or both levels. Participants were 21 HIV-1 infected and 19 healthy control men and women who also underwent Diffusion Tensor Imaging (DTI). HIV-1 participants showed impaired hierarchical perception owing to abnormally enhanced global facilitation effects but no impairment in attentional control on local-global feature selection. DTI metrics revealed poorer fiber integrity of the corpus callosum in HIV-1 than controls that was more pronounced in posterior than anterior regions. Analysis revealed a double dissociation of anterior and posterior callosal compromise in HIV-1 infection: Compromise in anterior but not posterior callosal fiber integrity predicted response conflict elicited by global targets, whereas compromise in posterior but not anterior callosal fiber integrity predicted response facilitation elicited by global targets. We conclude that component processes of visuospatial perception are compromised in HIV-1 infection attributable, at least in part, to degraded callosal microstructural integrity relevant for local-global feature integration. PMID:20018201

  3. Relationship between teat-end callosity and occurrence of clinical mastitis.

    PubMed

    Neijenhuis, F; Barkema, H W; Hogeveen, H; Noordhuizen, J P

    2001-12-01

    A longitudinal study in 15 herds, with a total of 2157 cows, was conducted to examine the relationship between teat-end callosity (TEC) and the incidence of clinical mastitis. During the 1.5-yr study period, clinical mastitis was diagnosed by the farmers based on clinical signs. Teat-end callosity was scored every month according to a teat-end callosity classification system, which discriminates between teat-end callosity thickness (TECT) and roughness (TECR). Differences in TECT between healthy and clinical mastitis quarters within infected cows were small but significant 3 mo before (0.13 higher), in the month during which the clinical mastitis occurred (0.08 higher), and in the following 2 mo (0.06 and 0.05 higher). To compare TECT and TECR between cows with and without clinical mastitis, 199 cows with clinical mastitis were paired with control cows based on herd, days in milk, and parity. Clinical mastitis cows had more TEC than their healthy herd mates, particularly when clinical mastitis occurred between the second and fifth months of lactation. Clinical Escherichia coli mastitis in the second or third month of lactation occurred in cows with less TEC than in cows with clinical mastitis caused by other pathogens. Clinical culture-negative, yeast, Klebsiella pneumoniae, and Enterobacter aerogenes mastitis cows had more TECT and TECR than other cows with clinical mastitis in the same month of lactation. Pointed teat ends had higher TECT and TECR than flat or inverted teat ends. Teat-end callosity thickness increased with a higher milk yield at peak production.

  4. 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.

  5. Association of efferent neurons to the compartmental architecture of the superior colliculus.

    PubMed Central

    Illing, R B

    1992-01-01

    The superior colliculus is a layered structure in the mammalian midbrain serving multimodal sensorimotor integration. Its intermediate layers are characterized by a compartmental architecture. These compartments are apparent through the clustering of terminals of major collicular afferents, which in many instances match the heterogeneous distribution of tissue components such as acetylcholinesterase, choline acetyltransferase, substance P, and parvalbumin. The present study was undertaken to determine whether efferent cells observe this compartmental architecture. It was found that subpopulations of both descending and ascending collicular efferents originate from perikarya situated in characteristic positions relative to the collicular compartments defined by elevated acetylcholinesterase activity and that their dendrites appear to be specifically coordinated with the heterogeneous environment. With the specific interlocking of afferent and efferent neurons through spatially distinguished neural networks, the compartmental architecture apparently constitutes an essential element for the determination of information flow in the superior colliculus. Images PMID:1438296

  6. 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.

  7. Hsp70 vaccination-induced primary immune responses in efferent lymph of the draining lymph node.

    PubMed

    Vrieling, Manouk; Santema, Wiebren; Vordermeier, Martin; Rutten, Victor; Koets, Ad

    2013-10-01

    Bovine paratuberculosis is a highly prevalent chronic infection of the small intestine in cattle, caused by Mycobacterium avium subspecies paratuberculosis (MAP). In earlier studies we showed the protective effect of Hsp70/DDA subunit vaccination against paratuberculosis. In the current study we set out to measure primary immune responses generated at the site of Hsp70 vaccination. Lymph vessel cannulation was performed to obtain efferent lymph from the prescapular lymph node draining the neck area where the vaccine was applied. Hsp70 vaccination induced a significant increase of CD21(+) B cells in efferent lymph, accounting for up to 40% of efferent cells post-vaccination. Proliferation (Ki67(+)) within the CD21(+) B cell and CD4(+) T cell populations peaked between day 3 and day 5 post-vaccination. From day 7, Hsp70-specific antibody secreting cells (ASCs) could be detected in efferent lymph. Hsp70-specific antibodies, mainly of the IgG1 isotype, were also detected from this time point onwards. However, post-vaccination IFN-γ production in efferent lymph was non-sustained. In conclusion, Hsp70-vaccination induces only limited Th1 type immune responsiveness as reflected in efferent lymph draining the vaccination site. This is in line with our previous observations in peripheral blood. The main primary immunological outcome of the Hsp70/DDA subunit vaccination is B cell activation and abundant Hsp70-specific IgG1 production. This warrants the question whether Hsp70-specific antibodies contribute to the observed protective effect of Hsp70 vaccination in calves.

  8. Vagal cardiac efferent innervation in F344 rats: Effects of chronic intermittent hypoxia.

    PubMed

    Cheng, Zixi Jack

    2017-03-01

    Chronic intermittent hypoxia (CIH), which is a physiological consequence of obstructive sleep apnea, reduces baroreflex control of heart rate (HR). Previously, we showed that the heart rate (HR) response to electrical stimulation of the vagal efferent nerve was significantly increased following CIH in F344 rats. Since vagal cardiac efferent from the nucleus ambiguus (NA) project to cardiac ganglia and regulate HR, we hypothesized that vagal cardiac efferent innervation of cardiac ganglia is reorganized. Young adult F344 rats were exposed either to room air (RA) or to intermittent hypoxia for 35-50days. Fluorescent tracer DiI was injected into the NA to label vagal efferent innervation of cardiac ganglia which had been counterstained by Fluoro-Gold (FG) injections (i.p). Confocal microscopy was used to examine vagal cardiac efferent axons and terminals in cardiac ganglia. NA axons entered cardiac ganglia and innervated principal neurons (PNs) with robust basket endings in both RA control and CIH animals. In addition, the percentage of PNs which were innervated by DiI-labeled fibers in ganglia was similar. In CIH rats, abnormally large swollen cardiac axon segments and disorganized terminals as well as leaky endings were observed. In general, vagal efferent terminal varicosities around PNs appeared larger and the number of varicosities was significantly increased. Interestingly, some cardiac axons had sprouting-like terminal structures in the cardiac ganglia as well as in cardiac muscle, which had not been found in RA control. Finally, CIH increased the size of PNs and reduced the ratio of nucleus to PN somata. Thus, CIH significantly remodeled the structure of vagal cardiac axons and terminals in cardiac ganglia as well as cardiac PNs.

  9. Acoustic input and efferent activity regulate the expression of molecules involved in cochlear micromechanics

    PubMed Central

    Lamas, Veronica; Arévalo, Juan C.; Juiz, José M.; Merchán, Miguel A.

    2015-01-01

    Electromotile activity in auditory outer hair cells (OHCs) is essential for sound amplification. It relies on the highly specialized membrane motor protein prestin, and its interactions with the cytoskeleton. It is believed that the expression of prestin and related molecules involved in OHC electromotility may be dynamically regulated by signals from the acoustic environment. However little is known about the nature of such signals and how they affect the expression of molecules involved in electromotility in OHCs. We show evidence that prestin oligomerization is regulated, both at short and relatively long term, by acoustic input and descending efferent activity originating in the cortex, likely acting in concert. Unilateral removal of the middle ear ossicular chain reduces levels of trimeric prestin, particularly in the cochlea from the side of the lesion, whereas monomeric and dimeric forms are maintained or even increased in particular in the contralateral side, as shown in Western blots. Unilateral removal of the auditory cortex (AC), which likely causes an imbalance in descending efferent activity on the cochlea, also reduces levels of trimeric and tetrameric forms of prestin in the side ipsilateral to the lesion, whereas in the contralateral side prestin remains unaffected, or even increased in the case of trimeric and tetrameric forms. As far as efferent inputs are concerned, unilateral ablation of the AC up-regulates the expression of α10 nicotinic Ach receptor (nAChR) transcripts in the cochlea, as shown by RT-Quantitative real-time PCR (qPCR). This suggests that homeostatic synaptic scaling mechanisms may be involved in dynamically regulating OHC electromotility by medial olivocochlear efferents. Limited, unbalanced efferent activity after unilateral AC removal, also affects prestin and β-actin mRNA levels. These findings support that the concerted action of acoustic and efferent inputs to the cochlea is needed to regulate the expression of major

  10. Modulation of vagal efferent fibre discharge by mechanoreceptors in the stomach, duodenum and colon of the ferret.

    PubMed Central

    Grundy, D; Salih, A A; Scratcherd, T

    1981-01-01

    1. A single-fibre-dissection technique was used to investigate the reflex modulation of vagal efferent fibre discharge by afferent fibres from various parts of the gastrointestinal tract of the urethane-anaesthetized ferret. 2. All but four of the 168 efferent fibres isolated in this study were spontaneously active. The majority of these had discharge frequencies of less than 6 spikes/sec. 3. All the efferent units received an afferent input from mechanoreceptors in the stomach. Two main types of response to gastric distension were seen: (i) an increase in efferent discharge and (ii) a decrease or complete suppression of efferent discharge. 4. The vagal efferent discharge was also modulated by duodenal and colonic distension, with the major effect being one of inhibition. 5. Bilateral vagotomy completely abolished the response to gastric distension in 68% of the units tested. The response to colonic and duodenal distension, however, was relatively unaffected by vagotomy. Thus the vagus provides the major afferent pathway from the stomach to these vagal efferent fibres, whilst the major input from the duodenum and colon is via a non-vagal pathway. Both vagal and splanchnic afferents therefore converge on to the vagal nucleus. 6. The destinations of these vagal efferent fibres and their possible functions are discussed. PMID:7320920

  11. 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…

  12. Reactive amyloidosis associated with ischial callosititis: a report with histology of ischial callosities in rhesus macaques (Macaca mulatta)

    PubMed Central

    Liu, David X.; Gilbert, Margaret H.; Wang, Xiaolei; Didier, Peter J.; Veazey, Ronald S.

    2014-01-01

    Ischial callosities have received little attention in veterinary medicine even though they are distinguishing anatomic organs. The organs are characterized by a pair of hairless pads of thickened epidermis, located bilaterally in the gluteal region, which overlay the tuberosities of the ischia of all Old World monkeys, gibbons, and siamangs. The current report describes a case of reactive amyloidosis associated with ischial callosititis in a rhesus macaque (Macaca mulatta). Amyloid A (AA) protein was found in the liver, spleen, small intestine, mesenteric lymph nodes, and ischial callosities by histology, Congo red stain, and immunohistochemistry. Confocal microscopy showed that many cluster of differentiation (CD)68-positive macrophages within the ischial callosities contained intracellular AA protein, which suggests that CD68-positive macrophages have an important role in the pathogenesis of reactive amyloidosis in nonhuman primates. The normal histology of ischial callosities of rhesus macaques is also documented in this report. PMID:23104953

  13. Reactive amyloidosis associated with ischial callosititis: a report with histology of ischial callosities in rhesus macaques (Macaca mulatta).

    PubMed

    Liu, David X; Gilbert, Margaret H; Wang, Xiaolei; Didier, Peter J; Veazey, Ronald S

    2012-11-01

    Ischial callosities have received little attention in veterinary medicine even though they are distinguishing anatomic organs. The organs are characterized by a pair of hairless pads of thickened epidermis, located bilaterally in the gluteal region, which overlay the tuberosities of the ischia of all Old World monkeys, gibbons, and siamangs. The current report describes a case of reactive amyloidosis associated with ischial callosititis in a rhesus macaque (Macaca mulatta). Amyloid A (AA) protein was found in the liver, spleen, small intestine, mesenteric lymph nodes, and ischial callosities by histology, Congo red stain, and immunohistochemistry. Confocal microscopy showed that many cluster of differentiation (CD)68-positive macrophages within the ischial callosities contained intracellular AA protein, which suggests that CD68-positive macrophages have an important role in the pathogenesis of reactive amyloidosis in nonhuman primates. The normal histology of ischial callosities of rhesus macaques is also documented in this report.

  14. Elevated Early Callose Deposition Results in Complete Penetration Resistance to Powdery Mildew in Arabidopsis1[C][W][OA

    PubMed Central

    Ellinger, Dorothea; Naumann, Marcel; Falter, Christian; Zwikowics, Claudia; Jamrow, Torsten; Manisseri, Chithra; Somerville, Shauna C.; Voigt, Christian A.

    2013-01-01

    A common response by plants to fungal attack is deposition of callose, a (1,3)-β-glucan polymer, in the form of cell wall thickenings called papillae, at site of wall penetration. While it has been generally believed that the papillae provide a structural barrier to slow fungal penetration, this idea has been challenged in recent studies of Arabidopsis (Arabidopsis thaliana), where fungal resistance was found to be independent of callose deposition. To the contrary, we show that callose can strongly support penetration resistance when deposited in elevated amounts at early time points of infection. We generated transgenic Arabidopsis lines that express POWDERY MILDEW RESISTANT4 (PMR4), which encodes a stress-induced callose synthase, under the control of the constitutive 35S promoter. In these lines, we detected callose synthase activity that was four times higher than that in wild-type plants 6 h post inoculation with the virulent powdery mildew Golovinomyces cichoracearum. The callose synthase activity was correlated with enlarged callose deposits and the focal accumulation of green fluorescent protein-tagged PMR4 at sites of attempted fungal penetration. We observed similar results from infection studies with the nonadapted powdery mildew Blumeria graminis f. sp. hordei. Haustoria formation was prevented in resistant transgenic lines during both types of powdery mildew infection, and neither the salicylic acid-dependent nor jasmonate-dependent pathways were induced. We present a schematic model that highlights the differences in callose deposition between the resistant transgenic lines and the susceptible wild-type plants during compatible and incompatible interactions between Arabidopsis and powdery mildew. PMID:23335625

  15. mGluR1 enhances efferent inhibition of inner hair cells in the developing rat cochlea.

    PubMed

    Ye, Zhanlei; Goutman, Juan D; Pyott, Sonja J; Glowatzki, Elisabeth

    2017-02-17

    Just before the onset of hearing, the inner hair cells (IHCs) receive inhibitory efferent input from cholinergic medial olivocochlear (MOC) neurons originating in the brainstem. This input may serve a role in the maturation of the ascending (afferent) auditory system by inhibiting spontaneous activity of the IHCs. To investigate the molecular mechanisms regulating these IHC efferent synapses, we combined electrical stimulation of the efferent fibres with patch clamp recordings from the IHCs to measure efferent synaptic strength. By examining evoked responses, we show that activation of mGluRs by general and group I specific mGluR agonists enhances IHC efferent inhibition. This enhancement is blocked by application of a group I mGluR1-specific antagonist, indicating that enhancement of IHC efferent inhibition is mediated by group I mGluRs and specifically by mGluR1s. By comparing spontaneous and evoked responses, we show that group I mGluR agonists act presynaptically to increase neurotransmitter release without affecting postsynaptic responsiveness. Moreover, endogenous glutamate released from the IHCs also enhances IHC efferent inhibition via the activation of group I mGluRs. Finally, immunofluorescent analysis indicates that the efferent terminals are sufficiently close to IHC glutamate release sites to allow activation of mGluRs on the efferent terminals by glutamate spillover. Together, these results suggest that glutamate released from the IHCs activates group I mGluRs (mGluR1s), likely present on the efferent terminals, which, in turn, enhances release of acetylcholine and inhibition of the IHCs. Thus, mGluRs establish a local negative feedback loop positioned to regulate IHC activity and maturation of the ascending auditory system in the developing cochlea. This article is protected by copyright. All rights reserved.

  16. Wulst efferents in the little owl Athene noctua: an investigation of projections to the optic tectum.

    PubMed

    Casini, G; Porciatti, V; Fontanesi, G; Bagnoli, P

    1992-01-01

    The efferent projections from the Wulst were studied in the little owl, Athene noctua, using anterograde migration of wheat-germ-agglutinin conjugated horseradish peroxidase (WGA-HRP). Wulst projections were distributed to telencephalic, diencephalic and mesencephalic targets in a general pattern similar to that previously described in other avian species. Our results on the organization of the Wulst-optic tectum pathway in the little owl reveal well defined and laminarly arranged terminal projections into the superficial tectal layers, with a distribution suggestive of topographical relationships between neurons of origin in the Wulst and termination fields in the optic tectum. In contrast to lateral-eyed birds, the little owl possesses conspicuous contralateral projections to the optic tectum. Ipsilateral and contralateral efferents are restricted to different tectal regions, i.e. ipsilateral projections to the caudo-dorsal and contralateral projections to the rostro-ventral optic tectum. In addition, the anterior and posterior Wulst differentially contribute to the ipsilateral and contralateral projections to the optic tectum. This differential organization of Wulst efferents, as well as the presence of substantial contralateral projections, might be related to the high degree of binocular overlap typical of frontal-eyed birds. At a functional level, electric potentials recorded in the optic tectum and evoked by visual stimulation showed that information from one eye can reach the ipsilateral optic tectum. After Wulst ablation, the amplitude of these potentials was significantly reduced, indicating that Wulst efferents may influence visually-evoked activity in the optic tectum.

  17. The postnatal maturation of efferent tubules in the rat: a light and electron microscopy study.

    PubMed

    Francavilla, S; Moscardelli, S; Bruno, B; Barcellona, P S; De Martino, C

    1986-07-01

    The postnatal maturation of the epithelium and tubule wall of efferent tubules in the rat was investigated by light and transmission electron microscopy, from birth to 50 days of age, when sperms were released from the seminiferous tubules and appeared in the genital duct. At the end of the first week of life, an endocytotic apparatus is differentiated in the epithelial cells. During the third week of life, efferent tubules developed specializations for the transport of sperms and fluids, namely the appearance of ciliated elements interspersed among the principal cells of the epithelium, and differentiation of myoid elements in the tubule wall. The appearance of specializations related to endocytosis and fluid transport across the epithelium preceded the canalization of the seminiferous cords which, in fact, is reported to appear at the end of the second week of life in the rat, along with the initial secretion of testicular fluid. This suggested that the maturation of efferent tubules is not triggered by the passage of testicular fluid, as surmised for the postnatal differentiation of caput epididymis. The postnatal maturation of efferent tubules was almost complete 35 days after birth. The appearance of sperms in the genital duct of 50-day-old animals was not associated with any remarkable structural change.

  18. Efferent and Aesthetic Stance: Understanding the Definition of Lois Lowry's "The Giver" as Metaphor.

    ERIC Educational Resources Information Center

    Menexas, Vicky

    1997-01-01

    Clarifies the "efferent" and "aesthetic" stance on Louise Rosenblatt's theoretical continuum by relating her model to the plot, characters, and scenes in Lois Lowry's "The Giver." Shows that Rosenblatt's view applies to the ways readers read texts and to the way characters in the texts read their text-worlds. Presents…

  19. 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…

  20. [Response of efferent vestibular fibers to horizontal rotation in frogs (Rana esculenta L.)].

    PubMed

    Caston, J; Gribenski, A

    1975-01-01

    The activity of efferent vestibular fibres has been recorded on the nerve of the left vertical anterior semicircular canal detached from its ampulla during rotations in the horizontal plane. Different types of responses have been found; they are noted in table I and pictured on fig. 2.

  1. Hyperactive auditory efferent system and lack of acoustic reflexes in Williams syndrome.

    PubMed

    Attias, Joseph; Raveh, Eyal; Ben-Naftali, Naomi Farber; Zarchi, Omer; Gothelf, Doron

    2008-01-01

    The auditory efferent system and acoustic reflexes have been investigated in patients with Williams syndrome (WS). Twenty-one patients aged 6-26 years with a genetically confirmed diagnosis of WS and with reported hyperacusis were compared with 21 normally developing age-matched subjects. The medial olivocochlear (MOC) efferent system was tested by stimulation of the contralateral ear with increasing levels of white noise, while recording transient evoked otoacoustic emissions (TEOAE) in the ipsilateral ear. The suppression effect on the amplitudes of the TEOAE was computed for each contralateral stimulus level. This measure reflects the strength of the MOC efferent system. In addition, the thresholds of ipsilateral and contralateral acoustic reflexes in response to 1, 2 and 4 kHz tones as well as to broadband stimuli were also recorded. Results showed that patients with WS had a significantly higher suppression effect of the MOC reflex on TEOAE. Ipsilateral and contralateral acoustic reflexes to tonal and broadband stimuli presented at maximum stimulus intensities were absent in 62-86% of the patients with WS. In the remainder, acoustic reflexes were elicited at lower auditory sensation thresholds than in controls. Hyperexcitability of the MOC efferent system coupled with absence of acoustic reflexes may contribute to the hyperacusis in WS and the consequent high-tone hearing loss induced by environmental noise. Both measures can be used for objective detection and thus, intervention of hyperacusis in the early stages of life.

  2. 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…

  3. Differential Effects of Motor Efference Copies and Proprioceptive Information on Response Evaluation Processes

    PubMed Central

    Stock, Ann-Kathrin; Wascher, Edmund; Beste, Christian

    2013-01-01

    It is well-kown that sensory information influences the way we execute motor responses. However, less is known about if and how sensory and motor information are integrated in the subsequent process of response evaluation. We used a modified Simon Task to investigate how these streams of information are integrated in response evaluation processes, applying an in-depth neurophysiological analysis of event-related potentials (ERPs), time-frequency decomposition and sLORETA. The results show that response evaluation processes are differentially modulated by afferent proprioceptive information and efference copies. While the influence of proprioceptive information is mediated via oscillations in different frequency bands, efference copy based information about the motor execution is specifically mediated via oscillations in the theta frequency band. Stages of visual perception and attention were not modulated by the interaction of proprioception and motor efference copies. Brain areas modulated by the interactive effects of proprioceptive and efference copy based information included the middle frontal gyrus and the supplementary motor area (SMA), suggesting that these areas integrate sensory information for the purpose of response evaluation. The results show how motor response evaluation processes are modulated by information about both the execution and the location of a response. PMID:23658624

  4. Differential effects of motor efference copies and proprioceptive information on response evaluation processes.

    PubMed

    Stock, Ann-Kathrin; Wascher, Edmund; Beste, Christian

    2013-01-01

    It is well-kown that sensory information influences the way we execute motor responses. However, less is known about if and how sensory and motor information are integrated in the subsequent process of response evaluation. We used a modified Simon Task to investigate how these streams of information are integrated in response evaluation processes, applying an in-depth neurophysiological analysis of event-related potentials (ERPs), time-frequency decomposition and sLORETA. The results show that response evaluation processes are differentially modulated by afferent proprioceptive information and efference copies. While the influence of proprioceptive information is mediated via oscillations in different frequency bands, efference copy based information about the motor execution is specifically mediated via oscillations in the theta frequency band. Stages of visual perception and attention were not modulated by the interaction of proprioception and motor efference copies. Brain areas modulated by the interactive effects of proprioceptive and efference copy based information included the middle frontal gyrus and the supplementary motor area (SMA), suggesting that these areas integrate sensory information for the purpose of response evaluation. The results show how motor response evaluation processes are modulated by information about both the execution and the location of a response.

  5. Relation of callosal structure to cognitive abilities in temporal lobe epilepsy.

    PubMed

    Schneider, Christine; Helmstaedter, Christoph; Luders, Eileen; Thompson, Paul M; Toga, Arthur W; Elger, Christian; Weber, Bernd

    2014-01-01

    The main objective of this paper is to analyze the influence of mesial temporal lobe epilepsy (mTLE) on the morphology of the corpus callosum (CC) and its relation to cognitive abilities. More specifically, we investigated correlations between intellectual abilities and callosal morphology, while additionally exploring the modulating impact of (a) side of seizure onset (b) age of disease onset. For this reason a large representative sample of patients with hippocampal sclerosis (n = 79; 35 males; 44 females; age: 18-63 years) with disease onset ranging from 0 to 50 years of age, and consisting of 46 left and 33 right mTLE-patients was recruited. Intelligence was measured using the Wechsler-Adult Intelligence Scale Revised. To get localizations of correlations with high anatomic precision, callosal morphology was examined using computational mesh-based modeling methods, applied to anatomical brain MRI scans. Intellectual performance was positively associated with callosal thickness in anterior and midcallosal callosal regions, with anterior parts being slightly more affected by age of disease onset and side of seizure onset than posterior parts. Earlier age at onset of epilepsy was associated with lower thickness in anterior and midcallosal regions. In addition, laterality of seizure onset had a significant influence on anterior CC morphology, with left hemispheric origin having stronger effects. We found that in mTLE, anterior and midcallosal CC morphology are related to cognitive performance. The findings support recent findings of detrimental effects of early onset mTLE on anterior brain regions and of a distinct effect particularly of left mTLE on frontal lobe functioning and structure. The causal nature of the relationship remains an open question, i.e., whether CC morphology impacts IQ development or whether IQ development impacts CC morphology, or both.

  6. The Syndrome of Frontonasal Dysplasia, Callosal Agenesis, Basal Encephalocele, and Eye Anomalies - Phenotypic and Aetiological Considerations.

    PubMed

    Richieri-Costa, Antonio; Guion-Almeida, Maria Leine

    2004-01-01

    We report ten sporadic cases of Brazilian patients with facial midline defects, callosal agenesis, basal encephalocele, and ocular anomalies. This very rare cluster of anomalies has been well reported before. However, only until recently it is recognized as a syndrome belonging to frontonasal dysplasia spectrum. The ten cases confirm a distinct clinical entity and help to define the phenotype more precisely than previously. Up to now etiology remains unknown, although we conjecture that it is due to a mutation in TGIF gene.

  7. Diffusion-weighted imaging in fetuses with unilateral cortical malformations and callosal agenesis.

    PubMed

    Glenn, O A; Quiroz, E M; Berman, J I; Studholme, C; Xu, D

    2010-06-01

    DWI was performed in fetuses with callosal agenesis and unilateral cortical malformations. ADC values were retrospectively measured in the developing white matter underlying the cortical malformation and compared with the corresponding contralateral white matter. In all 3 patients, ADC values were lower under the areas of cortical malformation compared with the normal contralateral side. Our findings suggest that there are structural differences in the developing white matter underlying areas of cortical malformation.

  8. Sense of effort revisited: relative contributions of sensory feedback and efferent copy.

    PubMed

    Scotland, Samantha; Adamo, Diane E; Martin, Bernard J

    2014-02-21

    Although controversial, muscular effort perception is frequently attributed to the efferent copy of the associated motor command. While peripheral/sensory information is thought to be necessary for force modulation/control, it is not involved in initial force production. We recently showed in right-handers, that perception of effort was asymmetric for grasp-force tasks. This asymmetry was related to individual differences in right and left hand strength and an intrinsic component. A difference in gain (input/output magnitude relationship) for each limb/hemisphere system was proposed as the mechanism explaining intrinsic asymmetries. To further investigate the relative contributions of efferent copy and sensory feedback to the sense of effort, vibration was used to distort sensory information from the muscles providing the reference force. Visual feedback (vision) of the reference hand force was also manipulated. The absolute error (AE) was generally larger in the vision than no-vision condition and the influence of reference hand vibration was significant for left hand matching of the right hand reference force. However, this effect was negligible when matching in the reverse condition. These two results may reflect an interaction between two phenomena: (1) visual feedback, which represents the total output force may not be congruent with the internal representation of effort associated with the efferent copy and eventually the proprioceptive feedback; and (2) a vibration-induced larger AE for left than right hand contralateral matching indicates that the contribution of proprioceptive feedback to force matching is significant for the left but not the right hand/hemisphere system. Overall, it may be suggested that in right-handers, the sense of effort associated with the right hand may be primarily based on the efferent copy while the left hand/hemisphere system may use a combination of efferent copy and proprioceptive feedback. However, the weight of each type of

  9. 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

  10. Activity-Dependent Callosal Axon Projections in Neonatal Mouse Cerebral Cortex

    PubMed Central

    Tagawa, Yoshiaki; Hirano, Tomoo

    2012-01-01

    Callosal axon projections are among the major long-range axonal projections in the mammalian brain. They are formed during the prenatal and early postnatal periods in the mouse, and their development relies on both activity-independent and -dependent mechanisms. In this paper, we review recent findings about the roles of neuronal activity in callosal axon projections. In addition to the well-documented role of sensory-driven neuronal activity, recent studies using in utero electroporation demonstrated an essential role of spontaneous neuronal activity generated in neonatal cortical circuits. Both presynaptic and postsynaptic neuronal activities are critically involved in the axon development. Studies have begun to reveal intracellular signaling pathway which works downstream of neuronal activity. We also review several distinct patterns of neuronal activity observed in the developing cerebral cortex, which might play roles in activity-dependent circuit construction. Such neuronal activity during the neonatal period can be disrupted by genetic factors, such as mutations in ion channels. It has been speculated that abnormal activity caused by such factors may affect activity-dependent circuit construction, leading to some developmental disorders. We discuss a possibility that genetic mutation in ion channels may impair callosal axon projections through an activity-dependent mechanism. PMID:23213574

  11. Cerebral and callosal organisation in a right hemisphere dominant "split brain" patient.

    PubMed Central

    Lutsep, H L; Wessinger, C M; Gazzaniga, M S

    1995-01-01

    Patients described in previous reports who have undergone corpus callostomy for control of seizures have been left hemisphere dominant for language. To determine the hemispheric localisation (and possible coexistence) of language and traditional right hemisphere skills in reversed dominance, the first right hemisphere dominant corpus callostomy patient was studied. Localisation of callosal functions was also investigated, as MRI showed 1.5 cm of spared callosal body. The patient, KO, a 15 year old girl with familial left handedness, underwent two stage callosotomy in 1988. Lateralised visually presented stimuli requiring same or different comparisons between visual fields showed chance performance. Oral naming and reading showed better performance by the right hemisphere than the left, whereas both hemispheres were proficient in auditory comprehension. Active voice syntax was above chance only in the right hemisphere. Face recognition was significantly better in the right hemisphere than in the left. Tasks requiring tactile comparisons between hands showed above chance performance except in the instance in which the non-dominant right hand was stimulated first in a point localisation task between hands. This case showed hemispheric coexistence of language and traditional right hemispheric skills in a corpus callosotomy patient with reversed language dominance. Tactile transfer was localised to the mid-posterior callosal body. Images PMID:7608710

  12. Variability in the distribution of callosal projection neurons in the adult rat parietal cortex.

    PubMed

    Ivy, G O; Gould, H J; Killackey, H P

    1984-07-23

    Previous reports have shown that the barrel field area of the parietal cortex of the adult rat contains relatively few callosal projection neurons, even though callosal projection neurons are abundant in this cortical region in the neonatal rat. Furthermore, it has been shown that many of the callosal neurons which seem to disappear as the animal matures do not die, but project to ipsilateral cortical areas. These findings rely on the ability of retrograde transport techniques which utilize injections of horseradish peroxidase (HRP) or of fluorescent dyes into one hemisphere. We now show that several technical modifications of the HRP technique yield a wider distribution of HRP-containing neurons in the contralateral barrel field area of the adult rat than previously reported. These include implants of HRP pellets into transected axons of the corpus callosum, the addition of DMSO and nonidet P40 to Sigma VI HRP, wheat germ agglutinin HRP and the use of tetramethyl benzidine as the chromogen in the reaction procedure. Our findings have implications for transport studies in general and for the development of the cortical barrel field in particular.

  13. Distribution of Callose Synthase, Cellulose Synthase, and Sucrose Synthase in Tobacco Pollen Tube Is Controlled in Dissimilar Ways by Actin Filaments and Microtubules1[W

    PubMed Central

    Cai, Giampiero; Faleri, Claudia; Del Casino, Cecilia; Emons, Anne Mie C.; Cresti, Mauro

    2011-01-01

    Callose and cellulose are fundamental components of the cell wall of pollen tubes and are probably synthesized by distinct enzymes, callose synthase and cellulose synthase, respectively. We examined the distribution of callose synthase and cellulose synthase in tobacco (Nicotiana tabacum) pollen tubes in relation to the dynamics of actin filaments, microtubules, and the endomembrane system using specific antibodies to highly conserved peptide sequences. The role of the cytoskeleton and membrane flow was investigated using specific inhibitors (latrunculin B, 2,3-butanedione monoxime, taxol, oryzalin, and brefeldin A). Both enzymes are associated with the plasma membrane, but cellulose synthase is present along the entire length of pollen tubes (with a higher concentration at the apex) while callose synthase is located in the apex and in distal regions. In longer pollen tubes, callose synthase accumulates consistently around callose plugs, indicating its involvement in plug synthesis. Actin filaments and endomembrane dynamics are critical for the distribution of callose synthase and cellulose synthase, showing that enzymes are transported through Golgi bodies and/or vesicles moving along actin filaments. Conversely, microtubules appear to be critical in the positioning of callose synthase in distal regions and around callose plugs. In contrast, cellulose synthases are only partially coaligned with cortical microtubules and unrelated to callose plugs. Callose synthase also comigrates with tubulin by Blue Native-polyacrylamide gel electrophoresis. Membrane sucrose synthase, which expectedly provides UDP-glucose to callose synthase and cellulose synthase, binds to actin filaments depending on sucrose concentration; its distribution is dependent on the actin cytoskeleton and the endomembrane system but not on microtubules. PMID:21205616

  14. Distribution of callose synthase, cellulose synthase, and sucrose synthase in tobacco pollen tube is controlled in dissimilar ways by actin filaments and microtubules.

    PubMed

    Cai, Giampiero; Faleri, Claudia; Del Casino, Cecilia; Emons, Anne Mie C; Cresti, Mauro

    2011-03-01

    Callose and cellulose are fundamental components of the cell wall of pollen tubes and are probably synthesized by distinct enzymes, callose synthase and cellulose synthase, respectively. We examined the distribution of callose synthase and cellulose synthase in tobacco (Nicotiana tabacum) pollen tubes in relation to the dynamics of actin filaments, microtubules, and the endomembrane system using specific antibodies to highly conserved peptide sequences. The role of the cytoskeleton and membrane flow was investigated using specific inhibitors (latrunculin B, 2,3-butanedione monoxime, taxol, oryzalin, and brefeldin A). Both enzymes are associated with the plasma membrane, but cellulose synthase is present along the entire length of pollen tubes (with a higher concentration at the apex) while callose synthase is located in the apex and in distal regions. In longer pollen tubes, callose synthase accumulates consistently around callose plugs, indicating its involvement in plug synthesis. Actin filaments and endomembrane dynamics are critical for the distribution of callose synthase and cellulose synthase, showing that enzymes are transported through Golgi bodies and/or vesicles moving along actin filaments. Conversely, microtubules appear to be critical in the positioning of callose synthase in distal regions and around callose plugs. In contrast, cellulose synthases are only partially coaligned with cortical microtubules and unrelated to callose plugs. Callose synthase also comigrates with tubulin by Blue Native-polyacrylamide gel electrophoresis. Membrane sucrose synthase, which expectedly provides UDP-glucose to callose synthase and cellulose synthase, binds to actin filaments depending on sucrose concentration; its distribution is dependent on the actin cytoskeleton and the endomembrane system but not on microtubules.

  15. Retinal Input Influences the Size and Corticocortical Connectivity of Visual Cortex During Postnatal Development in the Ferret

    PubMed Central

    Bock, A. S.; Kroenke, C. D.; Taber, E. N.; Olavarria, J. F.

    2013-01-01

    Retinal input plays an important role in the specification of topographically organized circuits and neuronal response properties, but the mechanism and timing of this effect is not known in most species. A system that shows dramatic dependence on retinal influences is the interhemispheric connection through the corpus callosum. Using ferrets, we analyzed the extent to which development of the visual callosal pattern depends on retinal influences, and explored the period during which these influences are required for normal pattern formation. We studied the mature callosal patterns in normal ferrets and in ferrets bilaterally enucleated (BE) at postnatal day 7 (P7) or P20. Callosal patterns were revealed in tangential sections from unfolded and flattened brains following multiple injections of horseradish peroxidase in the opposite hemisphere. We also estimated the effect of enucleation on the surface areas of striate and extrastriate visual cortex by using magnetic resonance imaging (MRI) data from intact brains. In BEP7 ferrets we found that the pattern of callosal connections was highly anomalous and the sizes of both striate and extrastriate visual cortex were significantly reduced. In contrast, enucleation at P20 had no significant effect on the callosal pattern, but it still caused a reduction in the size of striate and extrastriate visual cortex. Finally, retinal deafferentation had no significant effect on the number of visual callosal neurons. These results indicate that the critical period during which the eyes influence the development of callosal patterns, but not the size of visual cortex, ends by P20 in the ferret. PMID:21830218

  16. 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

  17. Difference in cochlear efferent activity between musicians and non-musicians.

    PubMed

    Micheyl, C; Khalfa, S; Perrot, X; Collet, L

    1997-03-03

    The present study aimed to confirm and extend the finding, suggested by the results of a previous study, of different auditory neural efferent functioning in musicians compared with non-musicians. The activity of the medial olivocochlear bundle (MOCB), an auditory efferent subsystem, was measured through the contralaterally induced attenuation of the amplitude of evoked otoacoustic emissions (EOAEs) in two groups, one of musicians and one of non-musicians, paired for age and sex. The results indicated a statistically significant difference between the two groups, with the musicians showing greater amplitude reduction upon contralateral noise stimulation than non-musicians (U-test, U = 204, p < 0.025, n = 32). These results indicate greater MOCB activity in musicians than in non-musicians. The possible origins and implications of this finding are discussed.

  18. 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.

  19. Relation between heel position and the distribution of forefoot plantar pressures and skin callosities in rheumatoid arthritis.

    PubMed Central

    Woodburn, J; Helliwell, P S

    1996-01-01

    OBJECTIVE: To investigate the relation between the position of the rearfoot and the distribution of forefoot plantar pressures and skin callosities in rheumatoid arthritis. METHOD: Plantar pressures and callosity patterns were measured in 102 rheumatoid arthritis patients (120 feet with normal heel alignment and 84 feet with valgus heel alignment measured by goniometry) and in 42 (84 feet) age matched healthy adults. Peak pressures (kPa) were measured across the metatarsal heads in-shoe using an FScan system and the distribution of plantar callosities was visually mapped for each foot. RESULTS: Peak pressures were significantly greater at all but the first metatarsal head in the rheumatoid normal heel alignment and healthy adult groups than in the rheumatoid valgus heel group. The feet of both the rheumatoid normal heel group and the healthy adult group behaved the same, the highest peak pressures registering on the central metatarsal heads. However, only in the rheumatoid group were plantar callosities found at these sites. In the rheumatoid valgus heel group, lateral metatarsal heads were frequently non-weightbearing, producing gross loading patterns with a dominant medial distribution. Peak pressures were shifted to the medial fore-foot accompanied by a higher prevalence of callosities. The results, however, failed to establish clearly an association between peak pressures and callus formation. CONCLUSIONS: In rheumatoid arthritis there is an important interrelation between the rearfoot position and forefoot pressure sites. PMID:8976636

  20. Relation between heel position and the distribution of forefoot plantar pressures and skin callosities in rheumatoid arthritis.

    PubMed

    Woodburn, J; Helliwell, P S

    1996-11-01

    To investigate the relation between the position of the rearfoot and the distribution of forefoot plantar pressures and skin callosities in rheumatoid arthritis. Plantar pressures and callosity patterns were measured in 102 rheumatoid arthritis patients (120 feet with normal heel alignment and 84 feet with valgus heel alignment measured by goniometry) and in 42 (84 feet) age matched healthy adults. Peak pressures (kPa) were measured across the metatarsal heads in-shoe using an FScan system and the distribution of plantar callosities was visually mapped for each foot. Peak pressures were significantly greater at all but the first metatarsal head in the rheumatoid normal heel alignment and healthy adult groups than in the rheumatoid valgus heel group. The feet of both the rheumatoid normal heel group and the healthy adult group behaved the same, the highest peak pressures registering on the central metatarsal heads. However, only in the rheumatoid group were plantar callosities found at these sites. In the rheumatoid valgus heel group, lateral metatarsal heads were frequently non-weightbearing, producing gross loading patterns with a dominant medial distribution. Peak pressures were shifted to the medial fore-foot accompanied by a higher prevalence of callosities. The results, however, failed to establish clearly an association between peak pressures and callus formation. In rheumatoid arthritis there is an important interrelation between the rearfoot position and forefoot pressure sites.

  1. In vivo treatments with fulvestrant and anastrozole differentially affect gene expression in the rat efferent ductules.

    PubMed

    Gomes, Gisele Renata Oliveira; Yasuhara, Fabiana; Siu, Erica Rosanna; Fernandes, Sheilla Alessandra Ferreira; Avellar, Maria Christina Werneck; Lazari, Maria Fatima Magalhaes; Porto, Catarina Segreti

    2011-01-01

    Estrogen plays a key role in maintaining the morphology and function of the efferent ductules. We previously demonstrated that the antiestrogen fulvestrant markedly affected gene expression in the rat efferent ductules. The mechanism of fulvestrant action to modulate gene expression may involve not only the blockade of ESR1 and ESR2 estrogen receptors, but also the activation of ESR1 and ESR2 when the receptors are tethered to AP-1 or SP1 transcription factors, or the activation of the G protein-coupled estrogen receptor 1. We therefore compared the effects of two strategies to interfere with estrogen action in the rat efferent ductules: treatment with fulvestrant or with the aromatase inhibitor anastrozole. Whereas fulvestrant markedly increased Mmp7 and Spp1, and reduced Nptx1 mRNA levels, no changes were observed with anastrozole. Fulvestrant caused changes in epithelial morphology that were not seen with anastrozole. Fulvestrant shifted MMP7 immunolocalization in the epithelial cells from the supranuclear to the apical region; this effect was less pronounced with anastrozole. In vitro studies of (35)S-methionine incorporation showed that protein release was increased, whereas tissue protein content in the efferent ductules of fulvestrant-treated rats was decreased. Although fulvestrant markedly affected gene expression, no changes were observed on AP-1 and SP1 DNA-binding activity. The blockade of ESRs seems to be the major reason explaining the differences between both treatments. At least some of the effects of fulvestrant appear to result from compensatory mechanisms activated by the dramatic changes caused by ESR1 blockade.

  2. Onset of cholinergic efferent synaptic function in sensory hair cells of the rat cochlea

    PubMed Central

    Roux, Isabelle; Wersinger, Eric; McIntosh, J. Michael; Fuchs, Paul A.; Glowatzki, Elisabeth

    2011-01-01

    In the developing mammalian cochlea, the sensory hair cells receive efferent innervation originating in the superior olivary complex. This input is mediated by α9/α10 nicotinic acetylcholine receptors (nAChRs) and is inhibitory due to the subsequent activation of calcium-dependent SK2 potassium channels. We examined the acquisition of this cholinergic efferent input using whole-cell voltage-clamp recordings from inner hair cells (IHCs) in acutely excised apical turns of the rat cochlea from embryonic day 21 to postnatal day 8 (P8). Responses to 1 mM acetylcholine (ACh) were detected from P0 on in almost every IHC. The ACh-activated current amplitude increased with age and demonstrated the same pharmacology as α9-containing nAChRs. Interestingly, at P0, the ACh response was not coupled to SK2 channels, so that the initial cholinergic response was excitatory and could trigger action potentials in IHCs. Coupling to SK current was detected earliest at P1 in a subset of IHCs and by P3 in every IHC studied. Clustered nAChRs and SK2 channels were found on IHCs from P1 on using Alexa Fluor 488 conjugated α-bungarotoxin and SK2 immunohistochemistry. The number of nAChRs clusters increased with age to 16 per IHC at P8. Cholinergic efferent synaptic currents first appeared in a subset of IHCs at P1 and by P3 in every IHC studied, contemporaneously with ACh-evoked SK currents, suggesting that SK2 channels may be necessary at onset of synaptic function. An analogous pattern of development was observed for the efferent synapses that form later (P6–P8) on outer hair cells in the basal cochlea. PMID:22016543

  3. Arc mRNA induction in striatal efferent neurons associated with response learning.

    PubMed

    Daberkow, D P; Riedy, M D; Kesner, R P; Keefe, K A

    2007-07-01

    The dorsal striatum is involved in motor-response learning, but the extent to which distinct populations of striatal efferent neurons are differentially involved in such learning is unknown. Activity-regulated, cytoskeleton-associated (Arc) protein is an effector immediate-early gene implicated in synaptic plasticity. We examined arc mRNA expression in striatopallidal vs. striatonigral efferent neurons in dorsomedial and dorsolateral striatum of rats engaged in reversal learning on a T-maze motor-response task. Male Sprague-Dawley rats learned to turn right or left for 3 days. Half of the rats then underwent reversal training. The remaining rats were yoked to rats undergoing reversal training, such that they ran the same number of trials but ran them as continued-acquisition trials. Brains were removed and processed using double-label fluorescent in situ hybridization for arc and preproenkephalin (PPE) mRNA. In the reversal, but not the continued-acquisition, group there was a significant relation between the overall arc mRNA signal in dorsomedial striatum and the number of trials run, with rats reaching criterion in fewer trials having higher levels of arc mRNA expression. A similar relation was seen between the numbers of PPE(+) and PPE(-) neurons in dorsomedial striatum with cytoplasmic arc mRNA expression. Interestingly, in behaviourally activated animals significantly more PPE(-) neurons had cytoplasmic arc mRNA expression. These data suggest that Arc in both striatonigral and striatopallidal efferent neurons is involved in striatal synaptic plasticity mediating motor-response learning in the T-maze and that there is differential processing of arc mRNA in distinct subpopulations of striatal efferent neurons.

  4. Neocortical efferent neurons with very slowly conducting axons: strategies for reliable antidromic identification.

    PubMed

    Swadlow, H A

    1998-02-20

    Although simple in concept, reliable antidromic identification of efferent populations poses numerous technical challenges and is subject to a host of sampling biases, most of which select against the detection of the neurons with slowly conducting axons. This problem is particularly acute in studies of the neocortex. Many neocortical efferent systems have large sub-populations with very slowly conducting, nonmyelinated axons and these elements have been relatively neglected in antidromic studies of neocortical neurons. The present review attempts to redress this problem by analyzing the steps that must necessarily precede antidromic identification and the sampling biases associated with each of these steps. These steps include (1) initial recognition that the microelectrode is near a neuron; (2) activation of the efferent axon via the stimulating electrode; (3) conduction of the antidromic impulse from stimulation site to soma; (4) detection of the antidromic spike in the extracellular record and (5) discriminating antidromic from synaptic activation. Experimental strategies are suggested for minimizing the sampling biases associated with each of these steps; most of which can be reduced or eliminated by appropriate experimental procedures. Careful attention to such procedures will make it possible to better understand the nature and function of the information flow along the very slowly conducting axonal systems of the neocortex.

  5. 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

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

    PubMed

    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.

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

    PubMed

    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.

  8. Responses to somatosensory input by afferent and efferent neurons in the vestibular nerve of the frog.

    PubMed

    Caston, J; Bricout-Berthout, A

    1984-01-01

    In the frog, we have recorded the activity of efferent and afferent fibers in the nerve of the horizontal semicircular canal in response to somatosensory stimulation. Recordings were made extracellularly by means of glass micropipettes filled with 2 M NaCl, and somatosensory stimulation was produced either by electrical stimulation of the sciatic nerve (ipsi- or contralateral to the recording side) or by vibratory stimulation of the gastrocnemius. The discharge frequency of 43% of the efferent fibers recorded was significantly increased by such stimulation, while the activity of the others was unaffected. The discharge rate of the afferent fibers was either significantly increased (in about 11% of the cases when the results were pooled together) or significantly decreased (in about 22% of the cases) by stimulation of the somatosensory system. The latencies of the responses ranged from 5 to 50 ms. These results show that: somatosensory input can influence the activity of the vestibular apparatus at the most peripheral level; modulation of the afferent discharge is mediated by the efferent vestibular system (EVS); the influence of the EVS on the vestibular afferent activity is both inhibitory and facilitatory, and the responses to somatosensory stimulation are mediated by both long-latency polysynaptic and short-latency oligosynaptic pathways. The functional significance of these two pathways is discussed.

  9. 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

  10. Retinal input to efferent target amacrine cells in the avian retina

    PubMed Central

    Lindstrom, Sarah H.; Azizi, Nason; Weller, Cynthia; Wilson, Martin

    2012-01-01

    The bird visual system includes a substantial projection, of unknown function, from a midbrain nucleus to the contralateral retina. Every centrifugal, or efferent, neuron originating in the midbrain nucleus makes synaptic contact with the soma of a single, unique amacrine cell, the target cell (TC). By labeling efferent neurons in the midbrain we have been able to identify their terminals in retinal slices and make patch clamp recordings from TCs. TCs generate Na+ based action potentials triggered by spontaneous EPSPs originating from multiple classes of presynaptic neurons. Exogenously applied glutamate elicited inward currents having the mixed pharmacology of NMDA, kainate and inward rectifying AMPA receptors. Exogenously applied GABA elicited currents entirely suppressed by GABAzine, and therefore mediated by GABAA receptors. Immunohistochemistry showed the vesicular glutamate transporter, vGluT2, to be present in the characteristic synaptic boutons of efferent terminals, whereas the GABA synthetic enzyme, GAD, was present in much smaller processes of intrinsic retinal neurons. Extracellular recording showed that exogenously applied GABA was directly excitatory to TCs and, consistent with this, NKCC, the Cl− transporter often associated with excitatory GABAergic synapses, was identified in TCs by antibody staining. The presence of excitatory retinal input to TCs implies that TCs are not merely slaves to their midbrain input; instead, their output reflects local retinal activity and descending input from the midbrain. PMID:20650017

  11. Organ-specific activation of the gastric branch of the efferent vagus nerve by ghrelin in urethane-anesthetized rats.

    PubMed

    Habara, Hiromi; Hayashi, Yujiro; Inomata, Norio; Niijima, Akira; Kangawa, Kenji

    2014-01-01

    Ghrelin plays multiple physiological roles such as growth hormone secretion and exerting orexigenic actions; however, its physiological roles in the electrical activity of autonomic nerves remain unclear. Here, we investigated the effects of human ghrelin on several autonomic nerve activities in urethane-anesthetized rats using an electrophysiological method. Intravenous injection of ghrelin at 3 μg/kg significantly and transiently potentiated the efferent activity of the gastric vagus nerve; however, it did not affect the efferent activity of the hepatic vagus nerve. The activated response to ghrelin in the gastric efferent vagus nerve was not affected by the gastric afferent vagotomy, suggesting that this effect was not induced via the gastric afferent vagus nerve. Ghrelin did not affect the efferent activity of the brown adipose tissue, adrenal gland sympathetic nerve, and the renal sympathetic nerve. In addition, rectal temperature and the plasma concentrations of norepinephrine, corticosterone, and renin were also not changed by ghrelin. These findings demonstrate that ghrelin stimulates the gastric efferent vagus nerve in an organ-specific manner without affecting the gastric afferent vagus nerve and that ghrelin does not acutely affect the efferent basal activity of the sympathetic nerve in rats.

  12. Sound localization in callosal agenesis and early callosotomy subjects: brain reorganization and/or compensatory strategies.

    PubMed

    Lessard, Nadia; Lepore, Franco; Villemagne, Jean; Lassonde, Maryse

    2002-05-01

    In order to evaluate the callosal involvement in sound localization, the present study examined the response accuracy of acallosal and early callosotomized subjects to monaural and binaural auditory targets presented in three-dimensional space. In these subjects, bilateral localization cues, such as interaural time and level differences, are integrated at the cortical and subcortical levels without the additional support of the callosal commissure. Because acallosal and early-callosotomized subjects have developed with this reduced source of binaural activation of cortical cells, they might have perfected their ability to use monaural sound localization cues. This hypothesis was tested by assessing localization performance under both binaural and monaural listening conditions. Five subjects with callosal agenesis, one callosotomized subject operated early in life and 19 control subjects were asked to localize broad-band noise bursts (BBNBs) of fixed intensity in the horizontal plane in an anechoic chamber. BBNBs were delivered through randomly selected loudspeakers. Two conditions were tested: (i) localization of a stationary sound source; and (ii) localization of a moving sound source. Listeners had to report the apparent stimulus location by pointing to its perceived position on a graduated perimeter. The results indicated that the acallosal subjects were less accurate than controls, but only in the binaural moving sound condition. More interestingly, in the monaural testing conditions, some of the acallosal subjects and the early-callosotomized subject performed significantly better than control subjects. This suggests that, because of the absence of the corpus callosum, these subjects compensate for their reduced access to cortically determined binaural cues by making more efficient use of monaural cues.

  13. Debridement of painful forefoot plantar callosities in rheumatoid arthritis: the CARROT randomised controlled trial.

    PubMed

    Siddle, Heidi J; Redmond, Anthony C; Waxman, Robin; Dagg, Abigail R; Alcacer-Pitarch, Begonya; Wilkins, Richard A; Helliwell, Philip S

    2013-05-01

    The objective of this study was to evaluate the long-term benefits of sharp scalpel debridement of painful forefoot plantar callosities in rheumatoid arthritis (RA). The null hypothesis: sharp scalpel debridement would offer no additional long-term advantage in terms of pain and function. Sixty-five people with RA were randomised to receive regular sharp scalpel debridement of painful forefoot plantar callosities in conjunction with a combined therapeutic approach or a combined therapeutic approach alone. The primary outcome measure was change at 18 months in participant-reported forefoot plantar pain measured by a 100-mm visual analogue scale (VAS). Secondary outcome measures were recorded at baseline and study exit and included revised Foot Function Index, Health Assessment Questionnaire, Foot Impact Scale and gait parameters. At 18 months, there were no differences between groups for the primary outcome VAS-measured forefoot plantar pain (left foot (F = 0.23, p = 0.635), right foot (F = 2.14, p = 0.148)). Within-group changes were highly significant (treatment arm, difference = 16.9 (95 % confidence interval (CI) 9.4, 24.4), t = 4.6, p < 0.0001; control arm, difference = 17.5 (95 % CI 9.4, 25.5), t = 4.4, p < 0.0001). There was little change in scores of overall function and foot impact in either group and there were no significant changes in gait parameters noted. The long-term effects of sharp scalpel debridement of painful forefoot plantar callosities in people with RA, when used in conjunction with a combined therapeutic approach, produced no additional benefit over the combined therapeutic approach alone. Trial registration http://www.controlled-trials.com/ISRCTN05190231.

  14. Outcome after anterior callosal section that spares the splenium in pediatric patients with drop attacks.

    PubMed

    Yang, Peng-Fan; Lin, Qiao; Mei, Zhen; Chen, Zi-Qian; Zhang, Hui-Jian; Pei, Jia-Sheng; Tian, Jun; Jia, Yan-Zeng; Zhong, Zhong-Hui

    2014-07-01

    We report on the efficacy and safety of extended, one-stage anterior callosal section that spares the splenium, which is performed in a large series of pediatric patients with drop attacks. Twenty-nine pediatric patients with drop attacks were studied (19 males and 10 females; mean age: 9.9 years). As presurgical factors, the age at surgery, age at seizure onset, age at drop attack onset, sex, hemiparesis, severe mental retardation, electroencephalograph abnormalities, magnetic resonance imaging abnormalities, and (18)fluorodeoxyglucose positron emission tomography abnormalities were analyzed. All patients had multiple seizure types, including drop attacks, atypical absence seizures, complex partial seizures, tonic seizures, and generalized tonic-clonic seizures. All patients were developmentally impaired and had electroencephalograph results showing marked secondary bilateral synchrony. All patients received an extended, one-stage callosal section, leaving only the splenium intact. The mean follow-up time was 5.2 years. Seizure outcome (cessation of seizures or ≥ 90% seizure reduction) was achieved in 79.3% of patients with drop attacks. The families assessed the overall daily function as improved in 62.1% of the patients, unchanged in 24.1%, and worse in 13.8%. Family satisfaction with callosotomy was achieved in 82.8% of the patients. The majority of the patients had some degree of a transient acute postoperative disconnection syndrome that disappeared within 3 weeks. Postoperatively, patients showed a consistent increase in attention levels. We conclude that extended callosal sectioning that leaves the splenium intact should be considered a good palliative surgical option for pediatric patients with drop attacks and that diminishment of epileptic discharge synchrony is a good prognostic sign following callosotomy. We also found that the postoperative increase in attention levels was as useful as seizure control in improving the quality of life of these

  15. [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.

  16. Arthrogryposis multiplex congenita with callosal agenesis and dentato-olivary dysplasia.

    PubMed

    Saito, Yoshiaki; Hayashi, Masaharu; Miyazono, Yayoi; Shimogama, Tatsuro; Ohno, Kousaku

    2006-05-01

    We report the autopsy case of a boy with arthrogryposis multiplex congenita, associated with callosal agenesis and dentato-olivary dysplasia. The patient manifested with dysmorphic facial features and suffered from intractable epilepsy during the neonatal period. These sets of complications suggest that a common molecular mechanism may be involved in the development of corpus callosum and the folding of the dentate and inferior olivary nuclei. Deep brain structures, including the brainstem and the cerebellum, may be involved in the pathophysiology of symptomatic generalized epilepsy. The differential diagnoses for the clinical and pathological characteristics of this patient are discussed.

  17. Microglia and astrocytes may participate in the shaping of visual callosal projections during postnatal development.

    PubMed

    Rochefort, N; Quenech'du, N; Watroba, L; Mallat, M; Giaume, C; Milleret, C

    2002-01-01

    In the adult cat, axons running through the corpus callosum interconnect the border between the visual cortical areas 17 and 18 (A17 and A18) of both hemispheres. This specific pattern emerges during postnatal development, under normal viewing conditions (NR), from the elimination of initially exuberant callosal projections. In contrast, if the postnatal visual experience is monocular from birth (MD), juvenile callosal projections are stabilised throughout A17 and A18. The present study aimed at using such a model in vivo to find indications of a contribution of glial cells in the shaping of projections in the developing CNS through interactions with neurones, both in normal and pathological conditions. As a first stage, the distribution and the morphology of microglial cells and astrocytes were investigated from 2 weeks to adulthood. Microglial cells, stained with isolectin-B4, were clustered in the white matter below A17 and A18. Until one month, these clustered cells displayed an ameboid morphology in NR group, while they were more ramified in MD animals. Their phenotype thus depends on the postnatal visual experience, which indicates that microglial cells may interact with axons of visual neurones. It also suggests that they may differentially contribute to the elimination and the stabilisation of juvenile exuberant callosal fibres in NR and MD animals respectively. Beyond one month, microglial cells were very ramified in both experimental groups. Astrocytes were labelled with a GFAP-antibody. The distributions of connexins 43 (Cx43) and 30 (Cx30), the main proteic components of gap junction channels in astrocytes, were also investigated using specific antibodies. Both in NR and MD groups, until 1 month, GFAP-positive astrocytes and Cx43 were mainly localised within the subcortical white matter. Then GFAP, Cx43 and Cx30 stainings progressively appeared within the cortex, throughout A17 and A18 but with a differential laminar expression according to the age

  18. 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. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  19. Three-dimensional reconstruction of efferent ducts in wild-type and Lgr4 knock-out mice.

    PubMed

    Lambot, Marie-Alexandra H; Mendive, Fernando; Laurent, Patrick; Van Schoore, Gregory; Noël, Jean-Christophe; Vanderhaeghen, Pierre; Vassart, Gilbert

    2009-04-01

    We have recently shown that Lgr4 knock-out (LGR4KO) male mice are infertile due to a developmental defect of the reproductive tract. Spermatozoa do not reach the epididymis and accumulate at the rete testis and efferent ducts (ED). We have proposed that in LGR4KO, ED might fail to connect resulting in blind-ended tubes that preclude the normal transit of sperm cells. To explore this possibility, we reconstructed the three-dimensional (3D) structure of the organ from serial microphotographs. The resulting model allowed to individualize and follow each ED from the testis up to the epididymis, and to display the spatial distribution of their content. The transit of spermatozoa is indeed blocked in LGR4KO mice but, contrary to the expectation, the ducts connect normally to each other, forming a single tube that flows into the epididymis, as in the wild-type animals. In the KO however, transit of the sperm is abruptly blocked at the same level syncytial-like aggregates appear in the luminal space. The model also allowed calculating, for the first time, morphometric parameters of the mouse ED, such as total volume, surface, radius, and length. These data unambiguously showed that ED in the mutant mouse are dramatically shortened and less convoluted than in the wild-type animal, providing an explanation to the phenotype observed in LGR4KO. Combined with in situ immunodetection or RNA in situ hybridization, 3D reconstruction of serial histological sections will provide an efficient mean to study expression profiles in organs which do not lend themselves to whole-mount studies.

  20. Developmental evolution of flowering plant pollen tube cell walls: callose synthase (CalS) gene expression patterns

    PubMed Central

    2011-01-01

    Background A number of innovations underlie the origin of rapid reproductive cycles in angiosperms. A critical early step involved the modification of an ancestrally short and slow-growing pollen tube for faster and longer distance transport of sperm to egg. Associated with this shift are the predominantly callose (1,3-β-glucan) walls and septae (callose plugs) of angiosperm pollen tubes. Callose synthesis is mediated by callose synthase (CalS). Of 12 CalS gene family members in Arabidopsis, only one (CalS5) has been directly linked to pollen tube callose. CalS5 orthologues are present in several monocot and eudicot genomes, but little is known about the evolutionary origin of CalS5 or what its ancestral function may have been. Results We investigated expression of CalS in pollen and pollen tubes of selected non-flowering seed plants (gymnosperms) and angiosperms within lineages that diverged below the monocot/eudicot node. First, we determined the nearly full length coding sequence of a CalS5 orthologue from Cabomba caroliniana (CcCalS5) (Nymphaeales). Semi-quantitative RT-PCR demonstrated low CcCalS5 expression within several vegetative tissues, but strong expression in mature pollen. CalS transcripts were detected in pollen tubes of several species within Nymphaeales and Austrobaileyales, and comparative analyses with a phylogenetically diverse group of sequenced genomes indicated homology to CalS5. We also report in silico evidence of a putative CalS5 orthologue from Amborella. Among gymnosperms, CalS5 transcripts were recovered from germinating pollen of Gnetum and Ginkgo, but a novel CalS paralog was instead amplified from germinating pollen of Pinus taeda. Conclusion The finding that CalS5 is the predominant callose synthase in pollen tubes of both early-diverging and model system angiosperms is an indicator of the homology of their novel callosic pollen tube walls and callose plugs. The data suggest that CalS5 had transient expression and pollen

  1. Callose-mediated resistance to pathogenic intruders in plant defense-related papillae

    PubMed Central

    Voigt, Christian A.

    2014-01-01

    Plants are exposed to a wide range of potential pathogens, which derive from diverse phyla. Therefore, plants have developed successful defense mechanisms during co-evolution with different pathogens. Besides many specialized defense mechanisms, the plant cell wall represents a first line of defense. It is actively reinforced through the deposition of cell wall appositions, so-called papillae, at sites of interaction with intruding microbial pathogens. The papilla is a complex structure that is formed between the plasma membrane and the inside of the plant cell wall. Even though the specific biochemical composition of papillae can vary between different plant species, some classes of compounds are commonly found which include phenolics, reactive oxygen species, cell wall proteins, and cell wall polymers. Among these polymers, the (1,3)-β-glucan callose is one of the most abundant and ubiquitous components. Whereas the function of most compounds could be directly linked with cell wall reinforcement or an anti-microbial effect, the role of callose has remained unclear. An evaluation of recent studies revealed that the timing of the different papilla-forming transport processes is a key factor for successful plant defense. PMID:24808903

  2. Wnt5a induces Ryk-dependent and -independent effects on callosal axon and dendrite growth.

    PubMed

    Clark, Charlotte E J; Richards, Linda J; Stacker, Steven A; Cooper, Helen M

    2014-02-01

    The non-canonical Wnt receptor, Ryk, promotes chemorepulsive axon guidance in the developing mouse brain and spinal cord in response to Wnt5a. Ryk has also been identified as a major suppressor of axonal regrowth after spinal cord injury. Thus, a comprehensive understanding of how growing axons and dendrites respond to Wnt5a-mediated Ryk activation is required if we are to overcome this detrimental activity. Here we undertook a detailed analysis of the effect of Wnt5a/Ryk interactions on axonal and dendritic growth in dissociated embryonic mouse cortical neuron cultures, focusing on callosal neurons known to be responsive to Ryk-induced chemorepulsion. We show that Ryk inhibits axonal growth in response to Wnt5a. We also show that Wnt5a inhibits dendrite growth independently of Ryk. However, this inhibition is relieved when Ryk is present. Therefore, Wnt5a-mediated Ryk activation triggers divergent responses in callosal axons and dendrites in the in vitro context.

  3. Interhemispheric transfer of kinesthetic information and line bisection task performance in patient with callosal agenesis.

    PubMed

    Makashvili, M; Chichinadze, K; Domianidze, T

    2009-09-01

    Patient G.J., male, 7 yrs, with callosal agenesis, was found perfectly able to cross-replicate hand postures in right-to left and left-to-right directions. Bimanual coordination as well as touch localization and intermanual matching were performed without errors. He failed to name 2 out of 8 objects, palpated with the left hand. At the age of 13 patient performed like normal controls in line bisection task, was successful in intermanual replication of hand postures and intermanual matching while failed to name 8 out of 12 familiar objects palpated with the left hand. G.J.'s case does not support idea about bilateral presentation of language centers and development of compensatory ipsilateral afferents in patients with callosal agenesis. Presence of anterior and interictal commissures in G.J. did not contribute to the exchange of information between sensory areas of the right hemisphere and language centers of the left half brain. However, normal intermanual matching and replication of hand postures, as well as high level of line bisection task performance suggests, that anterior and/or intertectal commissure could contribute to the functional integration of sensory areas of the two hemispheres.

  4. Predicting progression from mild cognitive impairment to Alzheimer's disease using longitudinal callosal atrophy.

    PubMed

    Lee, Sang Han; Bachman, Alvin H; Yu, Donghyeon; Lim, Johan; Ardekani, Babak A

    2016-01-01

    We investigate whether longitudinal callosal atrophy could predict conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD). Longitudinal (baseline + 1-year follow-up) MRI scans of 132 MCI subjects from the Alzheimer's Disease Neuroimaging Initiative were used. A total of 54 subjects did not convert to AD over an average (±SD) follow-up of 5.46 (±1.63) years, whereas 78 converted to AD with an average conversion time of 2.56 (±1.65) years. Annual change in the corpus callosum thickness profile was calculated from the baseline and 1-year follow-up MRI. A logistic regression model with fused lasso regularization for prediction was applied to the annual changes. We found a sex difference. The accuracy of prediction was 84% in females and 61% in males. The discriminating regions of corpus callosum differed between sexes. In females, the genu, rostrum, and posterior body had predictive power, whereas the genu and splenium were relevant in males. Annual callosal atrophy predicts MCI-to-AD conversion in females more accurately than in males.

  5. Hemispheric Asymmetry and Callosal Integration of Visuospatial Attention in Schizophrenia: A Tachistoscopic Line Bisection Study

    PubMed Central

    McCourt, Mark E.; Shpaner, Marina; Javitt, Daniel C.; Foxe, John J.

    2008-01-01

    Background A hallmark of visuospatial neglect syndrome is that patients with lesions to right parietal cortex misbisect horizontal lines far rightward of veridical center. Neurologically normal subjects misbisect lines with a systematic leftward bias (pseudoneglect). Both phenomena, as well as neuroimaging studies, disclose a predominant right hemisphere control of spatial attention. Numerous studies of patients with schizophrenia have implicated global deficits of either right or left hemisphere function, as well as compromised integrity of the corpus callosum. Methods To better understand the functional implications of schizophrenia we utilized a forced-choice tachistoscopic line bisection task to probe the status of right hemisphere control of spatial attention, and compared left- versus right-hand unimanual responses to index the degree of callosal transfer of visuospatial information in both patient and control groups. Results In contrast to the significant leftward bisection errors of control subjects, patients exhibit no significant leftward error. Whereas control subjects evince a significant correlation between left- and right-hand bisection errors, patients lack a significant intermanual correlation. Conclusions The lack of significant leftward bisection error of patients implies a deficit of right hemisphere function. The lack of a significant correlation between left- and right-hand bisection errors in patients implies a loss of callosal integrity. PMID:18485672

  6. Bilateral subcortical heterotopia with partial callosal agenesis in a mouse mutant.

    PubMed

    Rosen, G D; Azoulay, N G; Griffin, E G; Newbury, A; Koganti, L; Fujisaki, N; Takahashi, E; Grant, P E; Truong, D T; Fitch, R H; Lu, L; Williams, R W

    2013-04-01

    Cognition and behavior depend on the precise placement and interconnection of complex ensembles of neurons in cerebral cortex. Mutations that disrupt migration of immature neurons from the ventricular zone to the cortical plate have provided major insight into mechanisms of brain development and disease. We have discovered a new and highly penetrant spontaneous mutation that leads to large nodular bilateral subcortical heterotopias with partial callosal agenesis. The mutant phenotype was first detected in a colony of fully inbred BXD29 mice already known to harbor a mutation in Tlr4. Neurons confined to the heterotopias are mainly born in midgestation to late gestation and would normally have migrated into layers 2-4 of overlying neocortex. Callosal cross-sectional area and fiber number are reduced up to 50% compared with coisogenic wildtype BXD29 substrain controls. Mutants have a pronounced and highly selective defect in rapid auditory processing. The segregation pattern of the mutant phenotype is most consistent with a two-locus autosomal recessive model, and selective genotyping definitively rules out the Tlr4 mutation as a cause. The discovery of a novel mutation with strong pleiotropic anatomical and behavioral effects provides an important new resource for dissecting molecular mechanisms and functional consequences of errors of neuronal migration.

  7. Localization of sucrose synthase and callose in freeze-substituted secondary-wall-stage cotton fibers.

    PubMed

    Salnikov, Vadim V; Grimson, Mark J; Seagull, Robert W; Haigler, Candace H

    2003-06-01

    Methods for cryogenic fixation, freeze substitution, and embedding were developed to preserve the cellular structure and protein localization of secondary-wall-stage cotton (Gossypium hirsutum L.) fibers accurately for the first time. Perturbation by specimen handling was minimized by freezing fibers still attached to a seed fragment within 2 min after removal of seeds from a boll still attached to the plant. These methods revealed native ultrastructure, including numerous active Golgi bodies, multivesicular bodies, and proplastids. Immunolocalization in the context of accurate structure was accomplished after freeze substitution in acetone only. Quantitation of immunolabeling identified sucrose synthase both near the cortical microtubules and plasma membrane and in a proximal exoplasmic zone about 0.2 microm thick. Immunolabeling also showed that callose (beta-1,3-glucan) was codistributed with sucrose synthase within this exoplasmic zone. Similar results were obtained from cultured cotton fibers. The distribution of sucrose synthase is consistent with its having a dual role in cellulose and callose synthesis in secondary-wall-stage cotton fibers.

  8. [Right hemiasomatognosia and sensation of amputation caused by left subcortical lesion. Role of callosal disconnection].

    PubMed

    Cambier, J; Elghozi, D; Graveleau, P; Lubetzki, C

    1984-01-01

    A 72-year-old right-handed hypertensive man presented with a right brachial monoplegia, and hypesthesia of the right half of the body to touch and pricking, sparing the face. A CT scan 2 weeks later showed a spontaneous hyperdense area corresponding to a left subcortical parietal hematoma. The patient used his spontaneous language to express body image disturbances: intense prolonged feeling of amputation related to the upper limb and foot on the right side, hemiasomatognosia without anosognosia, autotopagnosia. Also associated were a right-sided visual negligence and a more general inability to handle spatial data leading to a temporospatial disorientation. Mild language disorders were suggestive of subcortical aphasia: normal incitation and repetition; with semantic paraphasias, poor verbal fluency. Furthermore comprehension of orders or propositions concerning spatial data were poor. Finally, there were signs suggestive of callosal disconnection: paradoxical extinction of the left ear during dichotic listening, agraphia and anomia of the left hand, ideomotor apraxia of the left upper limb, difficulty in visual transfer. The lesion interrupted thalamic tracts to parietal regions and callosal fibers linking parieto-occipital association areas. This twofold lesion was analyzed for each of the neuropsychological disturbances observed. Certain aspect of cerebral function in this patient were reminiscent of "split-brain" disorders. The left hemisphere which "speaks" fails to understand the feelings of the right hemisphere: unfamiliarity of places, sensations of illness, resulting in an unadapted speech. The pathophysiology of feeling of amputation is discussed.

  9. Arrested Development and Disrupted Callosal Microstructure Following Pediatric Traumatic Brain Injury: Relation to Neurobehavioral Outcomes

    PubMed Central

    Ewing-Cobbs, Linda; Prasad, Mary R.; Swank, Paul; Kramer, Larry; Cox, Charles S.; Fletcher, Jack M.; Barnes, Marcia; Zhang, Xiaoling; Hasan, Khader M.

    2008-01-01

    Chronic pediatric traumatic brain injury (TBI) is associated with significant and persistent neurobehavioral deficits. Using diffusion tensor imaging (DTI), we examined area, fractional anisotropy (FA), radial diffusion, and axial diffusion from six regions of the corpus callosum (CC) in 41 children and adolescents with TBI and 31 comparison children. Midsagittal cross-sectional area of the posterior body and isthmus was similar in younger children irrespective of injury status; however, increased area was evident in the older comparison children but was obviated in older children with TBI, suggesting arrested development. Similarly, age was correlated significantly with indices of tissue microstructure only for the comparison group. TBI was associated with significant reduction in FA and increased radial diffusivity in the posterior third of the CC and in the genu. The axial diffusivity did not differ by either age or group. Logistic regression analyses revealed that FA and radial diffusivity were equally sensitive to post-traumatic changes in 4 of 6 callosal regions; radial diffusivity was more sensitive for the rostral midbody and splenium. IQ, working memory, motor, and academic skills were correlated significantly with radial diffusion and/or FA from the isthmus and splenium only in the TBI group. Reduced size and microstructural changes in posterior callosal regions after TBI suggest arrested development, decreased organization, and disrupted myelination. Increased radial diffusivity was the most sensitive DTI-based surrogate marker of the extent of neuronal damage following TBI; FA was most strongly correlated with neuropsychological outcomes. PMID:18655838

  10. Contribution of lymph formation in the popliteal node to efferent lymph flow following stimulation of the sympathetic chain in the sheep.

    PubMed

    Thornbury, K D; McHale, N G; McGeown, J G

    1990-01-01

    Lymph flow and contraction frequency were measured in popliteal efferent lymphatics. Stimulation of the ipsilateral sympathetic chain resulted in an approximate threefold increase in lymph flow, while contraction frequency increased 28% (n = 6). Occlusion of the metatarsal afferent lymphatics with a pneumatic cuff reduced efferent flow from 18 to 4 microliters/min after 25 min (n = 5), indicating that approximately 80% of popliteal efferent lymph is derived from the foot. After occlusion of the afferent lymphatics, sympathetic stimulation failed to increase efferent lymph flow significantly, while efferent contraction frequency still showed a significant rise. It is concluded that lymph formation in the popliteal node does not contribute to the rise in efferent lymph flow following sympathetic stimulation.

  11. 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

  12. 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

  13. Purinergic stimulation of carotid body efferent glossopharyngeal neurones increases intracellular Ca2+ and nitric oxide production.

    PubMed

    Lowe, Michael; Park, Sung Jin; Nurse, Colin A; Campanucci, Verónica A

    2013-07-01

    The mammalian carotid body (CB) is a peripheral chemosensory organ that controls ventilation and is innervated by both afferent and efferent nerve fibres. The afferent pathway is stimulated by chemoexcitants, such as hypoxia, hypercapnia and acidosis. The efferent pathway causes inhibition of the sensory discharge via release of NO that originates mainly from neuronal nitric oxide synthase (nNOS)-positive autonomic neurones within the glossopharyngeal nerve (GPN). Recent studies in the rat indicate that these inhibitory GPN neurones and their processes express purinergic P2X receptors and can be activated by ATP, a key excitatory CB neurotransmitter. Here we tested the hypothesis that purinergic agonists stimulate a rise in [Ca(2+)]i, leading to nNOS activation and NO production in isolated GPN neurones, using the fluorescent probes fura-2 and 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM DA), respectively. ATP caused a dose-dependent increase in [Ca(2+)]i in GPN neurones (EC50 ≈ 1.92 μm) that was markedly inhibited by a combination of 100 μm suramin (a non-specific P2X blocker) and 100 nm Brilliant Blue G (a selective P2X7 blocker). ATP also stimulated NO production in GPN neurones, as revealed by an increase in DAF fluorescence; this NO signal was inhibited by purinergic blockers, chelators of extracellular Ca(2+), the nNOS inhibitor l-NAME and the NO scavenger carboxy-PTIO. The P2X2/3 and P2X7 agonists α,β,-methylene ATP and benzoyl ATP mimicked the effects of ATP. Taken together, these data indicate that ATP may contribute to negative feedback inhibition of CB sensory discharge via purinergic stimulation of NO production in efferent fibres.

  14. Central distribution of octavolateral afferents and efferents in a teleost (Mormyridae).

    PubMed

    Bell, C C

    1981-01-20

    The central distribution of afferents from individual eight nerve branches (N VIII) and mechanical lateral line end organs in mormyrid fish are described. Afferents were labeled with horseradish peroxidase (HRP) placed on the cut ends of the different N VIII branches and the anterior and posterior lateral line nerves. Descending, tangential, and magnocellular nuclei receive input almost exclusively from the utriculus and canals. Nucleus octavius receives afferents from the lateral line nerves and all N VIII branches, with one part receiving exclusive and bilateral input from the sacculus. Afferents from both lateral line nerves and all N VII branches, except the sacculus, end in eminentia granularis. Afferents from each of the two lateral line nerves and from each of three otolith branches of N VIII end in different regions of the anterior lateral line lobe, with some areas of overlap. Behavioral studies in other families of fish indicate that the utriculus and canals are critical for postural control, whereas the sacculus and possibly the lagena are concerned with hearing. Such findings, together with the results of this study, suggest that mormyrids and perhaps other fish possess separate auditory and vestibular centers within the octavolateral area. The HRP method also shows the cell bodies and axons of octavolateral efferents. N VIII and lateral line efferents arise from a common nucleus, and the central course of their axons parallels that of facial motoneurons. Axons of efferent cells divide to supply two or more branches of N VIII and some axons supply both lateral line and N VIII end organs.

  15. Callose Synthase GSL7 Is Necessary for Normal Phloem Transport and Inflorescence Growth in Arabidopsis1[W][OA

    PubMed Central

    Barratt, D.H. Paul; Kölling, Katharina; Graf, Alexander; Pike, Marilyn; Calder, Grant; Findlay, Kim; Zeeman, Samuel C.; Smith, Alison M.

    2011-01-01

    One isoform of callose synthase, Glucan Synthase-Like7 (GSL7), is tightly coexpressed with two isoforms of sucrose synthase (SUS5 and SUS6) known to be confined to phloem sieve elements in Arabidopsis (Arabidopsis thaliana). Investigation of the phenotype of gsl7 mutants of Arabidopsis revealed that the sieve plate pores of stems and roots lack the callose lining seen in wild-type plants. Callose synthesis in other tissues of the plant appears to be unaffected. Although gsl7 plants show only minor phenotypic alterations during vegetative growth, flowering stems are reduced in height and all floral parts are smaller than those of wild-type plants. Several lines of evidence suggest that the reduced growth of the inflorescence is a result of carbohydrate starvation. Levels of sucrose, hexoses, and starch are lower in the terminal bud clusters of gsl7 than in those of wild-type plants. Transcript levels of “starvation” genes expressed in response to low sugars are elevated in the terminal bud clusters of gsl7 plants, at the end of the night, and during an extended night. Pulse-chase experiments with 14CO2 show that transport of assimilate in the flowering stem is much slower in gsl7 mutants than in wild-type plants. We suggest that the callose lining of sieve plate pores is essential for normal phloem transport because it confers favorable flow characteristics on the pores. PMID:21098675

  16. Cochlear efferent neurones and protection against acoustic trauma: protection of outer hair cell receptor current and interanimal variability.

    PubMed

    Patuzzi, R B; Thompson, M L

    1991-07-01

    We have measured the changes in neural and microphonic sensitivity in the basal turn of the guinea-pig cochlea produced by intense acoustic overstimulation (10 kHz, 115 dB SPL for 60 s and 150 s). As reported previously, the drop in neural and microphonic sensitivities observed after overstimulation were highly correlated [Patuzzi et al. (1989) Hear. Res. 39, 189-202]. Presentation of a non-traumatizing pure-tone to the contralateral ear (10 kHz, 80 dB SPL) during acoustic overstimulation reduced the amount of acoustic trauma measured using the neural response or the microphonic response. Transection of the medial olivo-cochlear system of efferent fibres at the floor of the fourth ventricle abolished this protective effect of contralateral sound and dramatically reduced the variability in the data. Since the low-frequency microphonic is a simple measure of the receptor current through the outer hair cells, and this current probably plays a part in enhancing the mechanical sensitivity of the cochlea, the protection of the microphonic we have observed suggests that the efferent system protects neural sensitivity by protecting the mechano-electrical transduction of outer hair cells. The drop in variability after sectioning the efferents also suggests that inter-animal variations in susceptibility to noise trauma may be a consequence of differing tonic activity of the efferents, and/or a variation in the sensitivity of the efferent pathway.

  17. 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.

  18. 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

  19. Semaphorin 3A activates the guanosine triphosphatase Rab5 to promote growth cone collapse and organize callosal axon projections

    PubMed Central

    Wu, Kong-Yan; He, Miao; Hou, Qiong-Qiong; Sheng, Ai-Li; Yuan, Lei; Liu, Fei; Liu, Wen-Wen; Li, Guangpu; Jiang, Xing-Yu; Luo, Zhen-Ge

    2015-01-01

    Axon guidance (pathfinding) wires the brain during development and is regulated by various attractive and repulsive cues. Semaphorin 3A (Sema3A) is a repulsive cue, inducing the collapse of axon growth cones. In the mammalian forebrain, the corpus callosum is the major commissure that transmits information flow between the two hemispheres, and contralateral axons assemble into well-defined tracts. We found that the patterning of callosal axon projections in rodent layer II and III (L2/3) cortical neurons in response to Sema3A was mediated by the activation of Rab5, a small guanosine triphosphatase (GTPase) that mediates endocytosis, through the membrane fusion protein Rabaptin-5 and the Rab5 guanine nucleotide exchange factor (GEF) Rabex-5. Rabaptin-5 bound directly to Plexin-A1 in the Sema3A receptor complex [an obligate heterodimer formed by Plexin-A1 and neuropilin 1 (NP1)]; Sema3A enhanced this interaction in cultured neurons. Rabaptin-5 bridged the interaction between Rab5 and Plexin-A1. Sema3A stimulated endocytosis from the cell surface of callosal axon growth cones. In utero electroporation to reduce Rab5 or Rabaptin-5 impaired axon fasciculation or caused mistargeting of L2/3 callosal projections in rats. Over-expression of Rabaptin-5 or Rab5 rescued the defective callosal axon fasciculation or mistargeting of callosal axons caused by the loss of Sema3A–Plexin-A1 signaling in rats expressing dominant-negative Plexin-A1 or in NP1-deficient mice. Thus, our findings suggest that Rab5, its effector Rabaptin-5, and its regulator Rabex-5 mediate Sema3A-induced axon guidance during brain development. PMID:25161316

  20. Importance of rostral ventrolateral medulla neurons in determining efferent sympathetic nerve activity and blood pressure

    PubMed Central

    Kumagai, Hiroo; Oshima, Naoki; Matsuura, Tomokazu; Iigaya, Kamon; Imai, Masaki; Onimaru, Hiroshi; Sakata, Katsufumi; Osaka, Motohisa; Onami, Toshiko; Takimoto, Chie; Kamayachi, Tadashi; Itoh, Hiroshi; Saruta, Takao

    2012-01-01

    Accentuated sympathetic nerve activity (SNA) is a risk factor for cardiovascular events. In this review, we investigate our working hypothesis that potentiated activity of neurons in the rostral ventrolateral medulla (RVLM) is the primary cause of experimental and essential hypertension. Over the past decade, we have examined how RVLM neurons regulate peripheral SNA, how the sympathetic and renin-angiotensin systems are correlated and how the sympathetic system can be suppressed to prevent cardiovascular events in patients. Based on results of whole-cell patch-clamp studies, we report that angiotensin II (Ang II) potentiated the activity of RVLM neurons, a sympathetic nervous center, whereas Ang II receptor blocker (ARB) reduced RVLM activities. Our optical imaging demonstrated that a longitudinal rostrocaudal column, including the RVLM and the caudal end of ventrolateral medulla, acts as a sympathetic center. By organizing and analyzing these data, we hope to develop therapies for reducing SNA in our patients. Recently, 2-year depressor effects were obtained by a single procedure of renal nerve ablation in patients with essential hypertension. The ablation injured not only the efferent renal sympathetic nerves but also the afferent renal nerves and led to reduced activities of the hypothalamus, RVLM neurons and efferent systemic sympathetic nerves. These clinical results stress the importance of the RVLM neurons in blood pressure regulation. We expect renal nerve ablation to be an effective treatment for congestive heart failure and chronic kidney disease, such as diabetic nephropathy. PMID:22170390

  1. Afferent and efferent activity control in the design of brain computer interfaces for motor rehabilitation.

    PubMed

    Cho, Woosang; Vidaurre, Carmen; Hoffmann, Ulrich; Birbaumer, Niels; Ramos-Murguialday, Ander

    2011-01-01

    Stroke is a cardiovascular accident within the brain resulting in motor and sensory impairment in most of the survivors. A stroke can produce complete paralysis of the limb although sensory abilities are normally preserved. Functional electrical stimulation (FES), robotics and brain computer interfaces (BCIs) have been used to induce motor rehabilitation. In this work we measured the brain activity of healthy volunteers using electroencephalography (EEG) during FES, passive movements, active movements, motor imagery of the hand and resting to compare afferent and efferent brain signals produced during these motor related activities and to define possible features for an online FES-BCI. In the conditions in which the hand was moved we limited the movement range in order to control the afferent flow. Although we observed that there is a subject dependent frequency and spatial distribution of efferent and afferent signals, common patterns between conditions and subjects were present mainly in the low beta frequency range. When averaging all the subjects together the most significant frequency bin comparing each condition versus rest was exactly the same for all conditions but motor imagery. These results suggest that to implement an on-line FES-BCI, afferent brain signals resulting from FES have to be filtered and time-frequency-spatial features need to be used.

  2. Importance of rostral ventrolateral medulla neurons in determining efferent sympathetic nerve activity and blood pressure.

    PubMed

    Kumagai, Hiroo; Oshima, Naoki; Matsuura, Tomokazu; Iigaya, Kamon; Imai, Masaki; Onimaru, Hiroshi; Sakata, Katsufumi; Osaka, Motohisa; Onami, Toshiko; Takimoto, Chie; Kamayachi, Tadashi; Itoh, Hiroshi; Saruta, Takao

    2012-02-01

    Accentuated sympathetic nerve activity (SNA) is a risk factor for cardiovascular events. In this review, we investigate our working hypothesis that potentiated activity of neurons in the rostral ventrolateral medulla (RVLM) is the primary cause of experimental and essential hypertension. Over the past decade, we have examined how RVLM neurons regulate peripheral SNA, how the sympathetic and renin-angiotensin systems are correlated and how the sympathetic system can be suppressed to prevent cardiovascular events in patients. Based on results of whole-cell patch-clamp studies, we report that angiotensin II (Ang II) potentiated the activity of RVLM neurons, a sympathetic nervous center, whereas Ang II receptor blocker (ARB) reduced RVLM activities. Our optical imaging demonstrated that a longitudinal rostrocaudal column, including the RVLM and the caudal end of ventrolateral medulla, acts as a sympathetic center. By organizing and analyzing these data, we hope to develop therapies for reducing SNA in our patients. Recently, 2-year depressor effects were obtained by a single procedure of renal nerve ablation in patients with essential hypertension. The ablation injured not only the efferent renal sympathetic nerves but also the afferent renal nerves and led to reduced activities of the hypothalamus, RVLM neurons and efferent systemic sympathetic nerves. These clinical results stress the importance of the RVLM neurons in blood pressure regulation. We expect renal nerve ablation to be an effective treatment for congestive heart failure and chronic kidney disease, such as diabetic nephropathy.

  3. The effect on the efferent vagal nerves to the heart of stimulating atrial receptors in the dog.

    PubMed

    Walters, G E; Mary, D A

    1986-10-01

    In chloralose-anaesthetized dogs, distension of small balloons at the pulmonary vein-atrial junctions to stimulate atrial receptors with myelinated vagal afferent nerves causes an increase in heart rate but does not influence the activity in efferent vagal cardiac nerves. However, distension of these small balloons also stimulates atrial receptors with non-myelinated vagal and sympathetic afferent nerves, which are thought to affect the heart rate and activity in efferent vagal cardiac nerves. In the present investigation, seven dogs anaesthetized with chloralose were studied by distension of small balloons at the pulmonary vein-atrial junctions and in the left atrial appendage, and by graded cooling of the vagal nerves in the neck; cooling to 9 degrees C was used to prevent the increase in activity in myelinated vagal afferent nerves to distension of the small balloons and cooling to 0 degree C was used to prevent responses to the distension in all vagal afferent nerves. Eleven vagal efferent nerve fibers were studied which responded to stimulation of carotid baroreceptors and chemoreceptors. Distension of the small balloons did not affect the activity in these eleven efferent vagal nerve fibres, with the vagi at 37 degrees C or during vagal cooling to 9 degrees C or to 0 degree C. The results indicate that upon distension of the small balloons, none of the three types of atrial receptor influence the activity in efferent vagal cardiac nerves. The results support the conclusion that stimulation of atrial receptors with myelinated vagal afferent nerves, responsible for the reflex increase in heart rate, does not influence the activity in efferent vagal cardiac nerves.

  4. 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.

  5. Intermittent Alien Hand Syndrome and Callosal Apraxia in Multiple Sclerosis: Implications for Interhemispheric Communication

    PubMed Central

    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

  6. [Tonic conjugated action of receptor-receptor fibers and of the efferent vestibular system on the spontaneous afferene activity of a semicircular canal in the frog].

    PubMed

    Gribenski, A; Caston, J

    1976-01-01

    In the frog, the joint action of non-afferent vestibular systems [i.e. the efferent vestibular system and the receptor-receptor fibre system] on the afferent vestibular activity is null or very small. The receptor-receptor fibre system being inhibitory, it seems that the efferent vestibular system as a whole is facilitatory, which agrees with previous results.

  7. Efferent innervation of the inner hair cell region: origins and terminations of two lateral olivocochlear systems.

    PubMed

    Warr, W B; Boche, J B; Neely, S T

    1997-06-01

    The projections of lateral olivocochlear neurons (LOC), which terminate beneath inner hair cells (IHCs), were investigated by injecting biotinylated dextran amine into the lateral superior olivary nucleus (LSO) and the surrounding region in the rat. This region has been definitively shown to contain two types of olivocochlear neurons: small cells within the LSO (intrinsic neurons) and large cells (shell neurons) surrounding it (Vetter, D.E., Mugnaini, E., 1992. Distribution and dendritic features of three groups of rat olivocochlear neurons. Anat. Embryol. 185, 1-16). Labeled efferent axons were studied by light microscopy in whole mounts and radial sections of the organ of Corti (OC). It was found that injections confined to the LSO, which presumably affected mainly intrinsic neurons, labeled a cluster of axons in the osseous spiral lamina that entered the inner spiral bundle (ISB) and terminated in one or more dense patches that, in total basal-apical extent, spanned no more than 10-20% (1-2 mm) of the total length of the OC (10 mm). In contrast, injections affecting shell neurons produced labeled axons that entered the OC over a span of more than 50% of its length and which, as a group, coursed in the ISB for at least 80%, and sometimes more than 95% of total cochlear length. Study of individual axons in the OC revealed that intrinsic axons did not bifurcate upon entering the OC and traveled less than 1 mm before terminating in a discrete, dense arbor. In contrast, shell axons typically bifurcated into basal and apical branches that, in toto, traveled between 1 and 2 mm beneath the IHCs, forming numerous en passant swellings and a few terminal branches en route. The fact that localized injections of intrinsic neurons produced focal peaks of labeling in the cochlea, whereas similar injections of shell neurons produced a diffuse, non-focal projection that could extend for nearly the entire length of the cochlea, suggests that significant differences exist between

  8. The Role of Corpus Callosum Development in Functional Connectivity and Cognitive Processing

    PubMed Central

    Findlay, Anne M.; Honma, Susanne; Jeremy, Rita J.; Strominger, Zoe; Bukshpun, Polina; Wakahiro, Mari; Brown, Warren S.; Paul, Lynn K.; Barkovich, A. James; Mukherjee, Pratik; Nagarajan, Srikantan S.; Sherr, Elliott H.

    2012-01-01

    The corpus callosum is hypothesized to play a fundamental role in integrating information and mediating complex behaviors. Here, we demonstrate that lack of normal callosal development can lead to deficits in functional connectivity that are related to impairments in specific cognitive domains. We examined resting-state functional connectivity in individuals with agenesis of the corpus callosum (AgCC) and matched controls using magnetoencephalographic imaging (MEG-I) of coherence in the alpha (8–12 Hz), beta (12–30 Hz) and gamma (30–55 Hz) bands. Global connectivity (GC) was defined as synchronization between a region and the rest of the brain. In AgCC individuals, alpha band GC was significantly reduced in the dorsolateral pre-frontal (DLPFC), posterior parietal (PPC) and parieto-occipital cortices (PO). No significant differences in GC were seen in either the beta or gamma bands. We also explored the hypothesis that, in AgCC, this regional reduction in functional connectivity is explained primarily by a specific reduction in interhemispheric connectivity. However, our data suggest that reduced connectivity in these regions is driven by faulty coupling in both inter- and intrahemispheric connectivity. We also assessed whether the degree of connectivity correlated with behavioral performance, focusing on cognitive measures known to be impaired in AgCC individuals. Neuropsychological measures of verbal processing speed were significantly correlated with resting-state functional connectivity of the left medial and superior temporal lobe in AgCC participants. Connectivity of DLPFC correlated strongly with performance on the Tower of London in the AgCC cohort. These findings indicate that the abnormal callosal development produces salient but selective (alpha band only) resting-state functional connectivity disruptions that correlate with cognitive impairment. Understanding the relationship between impoverished functional connectivity and cognition is a key step

  9. 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.

  10. Studies on callose and cutin during the expression of competence and determination for organogenic nodule formation from internodes of Humulus lupulus var. Nugget.

    PubMed

    Fortes, Ana M; Testillano, Pilar S; Del Carmen Risueño, Maria; Pais, Maria S

    2002-09-01

    Callose and cutin deposition were followed by staining with Aniline Blue and Nile Red and by immunolocalization using antibodies raised against callose. Along with morphogenesis induction from internodes of Humulus lupulus var. Nugget, a temporal and spatial differential deposition of callose and cutin was observed. A cutin layer showing bright yellow autofluorescence appears, surrounding cells or groups of cells committed to express morphogenic competence. This cutin layer that evolves to a randomly organized network appeared underneath a callose layer and may create a specific cellular environment with altered permeability and altered receptors providing conditions for entering the cell cycle. The incipient callose accumulation in control explants cultured on basal medium suggests the involvement of callose in the initiation of the morphogenic programme leading to nodule formation. A scanning electron microscopic study during the organogenic process showed that before shoot bud regeneration, the cutin layer increases in thickness and acquires a smooth texture. This cutin layer is specific to nodular organogenic regions and disappeared with plantlet regeneration. This layer may control permeability to water and solute transfer throughout plantlet regeneration.

  11. Uptake of gentamicin by vestibular efferent neurons and superior olivary complex after transtympanic administration in guinea pigs

    PubMed Central

    Zhang, Yi-Bo; Zhang, Ru; Zhang, Wei-Feng; Steyger, Peter S.; Dai, Chun-Fu

    2013-01-01

    Transtympanic administration of gentamicin is a widely accepted and effective approach for treating patients with intractable vertigo. Previous studies have demonstrated the uptake, distribution and effects of gentamicin in peripheral vestibular and cochlear structures after transtympanic injection. However, little is known about whether transtympanically administered gentamicin is trafficked into more central auditory and vestibular structures and its effect on these structures. In this study, we used immunofluorescence to determine the distribution of gentamicin within the auditory and vestibular brainstem. We observed gentamicin immunolabeling bilaterally in the vestibular efferent neurons, and in the superior olivary complex, and ipsilaterally in the cochlear nucleus 24 h after transtympanic administration of gentamicin, and that the drug could still be detected in these locations 30 days after injection. In contrast, no gentamicin labeling was detected in the vestibular nuclear complex. In the vestibular efferent neurons and superior olivary complex, gentamicin labeling was detected in the cytoplasm and cell processes, while in the cochlear nucleus gentamicin is mainly localized outside and adjacent to the cell bodies of neurons. Nerve fibers in cochlear nucleus, root of eighth nerve, as well as descending pathways from the superior olivary complex, are also immunolabeled with gentamicin continuously. Based on these data, we hypothesize that retrograde axonal transport of gentamicin is responsible for the distribution of gentamicin in these efferent nuclei including vestibular efferent neurons and superior olivary complex and anterograde axonal transport into the ipsilateral cochlear nucleus. PMID:22063470

  12. Axon diameter relates to synaptic bouton size: structural properties define computationally different types of cortical connections in primates.

    PubMed

    Innocenti, Giorgio M; Caminiti, Roberto

    2017-04-01

    Neural connections are implemented by axons of different diameters, whose spectrum increases depending on species and areas. Axon diameter determines conduction velocity and is proportional to the size of the cell body of origin. We describe that in motor, callosal connections of the monkey thick axons distribute larger boutons than thin axons, suggesting that faster axons also release more neurotransmitter at their termination, probably activating more powerfully their targets.

  13. Conduction Properties Distinguish Unmyelinated Sympathetic Efferent Fibers and Unmyelinated Primary Afferent Fibers in the Monkey

    PubMed Central

    Ringkamp, Matthias; Johanek, Lisa M.; Borzan, Jasenka; Hartke, Timothy V.; Wu, Gang; Pogatzki-Zahn, Esther M.; Campbell, James N.; Shim, Beom; Schepers, Raf J.; Meyer, Richard A.

    2010-01-01

    Background Different classes of unmyelinated nerve fibers appear to exhibit distinct conductive properties. We sought a criterion based on conduction properties for distinguishing sympathetic efferents and unmyelinated, primary afferents in peripheral nerves. Methodology/Principal Findings In anesthetized monkey, centrifugal or centripetal recordings were made from single unmyelinated nerve fibers in the peroneal or sural nerve, and electrical stimuli were applied to either the sciatic nerve or the cutaneous nerve endings, respectively. In centrifugal recordings, electrical stimulation at the sympathetic chain and dorsal root was used to determine the fiber's origin. In centrifugal recordings, sympathetic fibers exhibited absolute speeding of conduction to a single pair of electrical stimuli separated by 50 ms; the second action potential was conducted faster (0.61 0.16%) than the first unconditioned action potential. This was never observed in primary afferents. Following 2 Hz stimulation (3 min), activity-dependent slowing of conduction in the sympathetics (8.6 0.5%) was greater than in one afferent group (6.7 0.5%) but substantially less than in a second afferent group (29.4 1.9%). In centripetal recordings, most mechanically-insensitive fibers also exhibited absolute speeding to twin pulse stimulation. The subset that did not show this absolute speeding was responsive to chemical stimuli (histamine, capsaicin) and likely consists of mechanically-insensitive afferents. During repetitive twin pulse stimulation, mechanosensitive afferents developed speeding, and speeding in sympathetic fibers increased. Conclusions/Significance The presence of absolute speeding provides a criterion by which sympathetic efferents can be differentiated from primary afferents. The differences in conduction properties between sympathetics and afferents likely reflect differential expression of voltage-sensitive ion channels. PMID:20140089

  14. Vagal nerve stimulation activates vagal afferent fibers that reduce cardiac efferent parasympathetic effects

    PubMed Central

    Yamakawa, Kentaro; Rajendran, Pradeep S.; Takamiya, Tatsuo; Yagishita, Daigo; So, Eileen L.; Mahajan, Aman; Shivkumar, Kalyanam

    2015-01-01

    Vagal nerve stimulation (VNS) has been shown to have antiarrhythmic effects, but many of these benefits were demonstrated in the setting of vagal nerve decentralization. The purpose of this study was to evaluate the role of afferent fiber activation during VNS on efferent control of cardiac hemodynamic and electrophysiological parameters. In 37 pigs a 56-electrode sock was placed over the ventricles to record local activation recovery intervals (ARIs), a surrogate of action potential duration. In 12 of 37 animals atropine was given systemically. Right and left VNS were performed under six conditions: both vagal trunks intact (n = 25), ipsilateral right (n = 11), ipsilateral left (n = 14), contralateral right (n = 7), contralateral left (n = 10), and bilateral (n = 25) vagal nerve transection (VNTx). Unilateral VNTx significantly affected heart rate, PR interval, Tau, and global ARIs. Right VNS after ipsilateral VNTx had augmented effects on hemodynamic parameters and increase in ARI, while subsequent bilateral VNTx did not significantly modify this effect (%change in ARI in intact condition 2.2 ± 0.9% vs. ipsilateral VNTx 5.3 ± 1.7% and bilateral VNTx 5.3 ± 0.8%, P < 0.05). Left VNS after left VNTx tended to increase its effects on hemodynamics and ARI response (P = 0.07), but only after bilateral VNTx did these changes reach significance (intact 1.1 ± 0.5% vs. ipsilateral VNTx 3.6 ± 0.7% and bilateral VNTx 6.6 ± 1.6%, P < 0.05 vs. intact). Contralateral VNTx did not modify VNS response. The effect of atropine on ventricular ARI was similar to bilateral VNTx. We found that VNS activates afferent fibers in the ipsilateral vagal nerve, which reflexively inhibit cardiac parasympathetic efferent electrophysiological and hemodynamic effects. PMID:26371172

  15. Short latency cutaneous reflex responses of gamma-efferents in the decerebrate cat.

    PubMed

    Murphy, P R; Hammond, G R

    1992-01-01

    The effect of single shock stimulation, up to 20 x threshold (T), of the sural nerve on the discharges of triceps surae gamma-efferents was investigated in decerebrate cats. Units were classified as static (12) or dynamic (7) on the basis of their resting discharge rates (Murphy et al. 1984). All neurones were excited at short latency by sural nerve stimulation and response size was graded with stimulus intensity. Short latency mixed or inhibitory responses were not evident. Although reflex effects first occurred at low stimulus strengths (less than or equal to 1.5T) in both types of efferent, most responses appeared at higher intensities (greater than 1.5T). The estimated central delays of the responses of static (3.0 +/- 1.1 ms, mean +/- SD) and dynamic (3.4 +/- 1.0 ms) gamma-motoneurones were not significantly different and are consistent with spinal oligosynaptic pathways. The present results differ from those of the only previous study (Johansson and Sojka 1985) of the short latency responses of triceps surae static and dynamic gamma-motoneurones to sural nerve stimulation, in which mixed and inhibitory effects were common in anaesthetised cats. Although differences in recording techniques and gamma sampling may account for the apparent disparity between these studies, it is also feasible that a difference in the setting of interneuronal pathways in the two types of preparation is responsible. The results are discussed in relation to the control of gamma-motoneurones with particular reference to the "final common input" hypothesis (Johansson 1981; Appelberg et al. 1983).

  16. Stimulation of the efferent limb before ileostomy closure: a randomized clinical trial.

    PubMed

    Abrisqueta, J; Abellan, I; Luján, J; Hernández, Q; Parrilla, P

    2014-12-01

    Postoperative ileus is the most common complication after ileostomy closure with an increase in morbidity, hospital stay, and health care costs. The aim of this study is to assess the utility of a new technique for reducing postoperative ileus after protective ileostomy closure. This is a prospective randomized study registered at ClinicalTrials.gov (NCT01881594). Patients were randomly assigned to undergo either stimulation through the efferent limb of the ileostomy before surgery or nonstimulation before surgery. This study was conducted at the Department of Surgery of the Virgen de la Arrixaca Clinical University Hospital (Murcia). Seventy patients underwent surgery for ileostomy closure. In 35 patients, during the 2 weeks before surgery, daily stimulation of the defunctionalized stomal segment was performed by using a thick solution (500 mL of physiological saline associated with 30 g of thickening agent, Nestle Resource, Vevey, Switzerland). In the other 35 patients, stimulation was not performed before surgery. The primary outcome was postoperative ileus. The secondary outcomes included time to tolerating a diet and postoperative stay. Both groups of patients were homogenous for demographic data, characteristics of the first rectal cancer operation, and intersurgery periods. After ileostomy closure, the stimulated group of patients had an earlier return to oral tolerance (1.06 vs 2.57 days; p = 0.007) and passage of flatus or stool (1.14 vs 2.85 days; p <0.001) than the nonstimulated group of patients. The incidence of postoperative ileus (2.85% vs 20%; p = 0.024) and hospital stay (2.49 vs 4.61 days; p = 0.002) was also lower in the stimulated patients. Small numbers of patients means that no definitive statements can be made regarding the effectiveness of this technique. Stimulation of the efferent limb of the ileostomy before closure is a safe technique that reduces postoperative ileus and fosters early intestinal transit and oral tolerance with a shorter

  17. Vagal efferent stimulation protects against Mesobuthus tamulus venom-induced acute respiratory distress syndrome in rats.

    PubMed

    Akella, Aparna; Deshpande, Shripad B

    2015-12-15

    Mesobuthus tamulus (MBT) venom and oleic acid (OA) have been shown to produce acute respiratory distress syndrome (ARDS) involving different mechanisms. The role of vagally mediated anti-inflammatory pathway in ARDS is poorly understood. Therefore, the effects of vagal efferent stimulation on these two models of ARDS were examined. Experiments were performed on anesthetized adult rats. Parameters like ventilatory changes (respiratory frequency and minute ventilation), hypoxemic status (PaO2/FiO2 ratio; P/F ratio), survival time, pulmonary water content and histopathological evidences of lung injury were determined to assess the severity of ARDS. In addition, heart rate (HR) and mean arterial pressure (MAP) were monitored. Injection of OA/MBT venom produced respiratory alterations, hypoxemia, pulmonary edema and histopathological changes demonstrating the development of ARDS. In both the groups, animals died around 60 min. Tachypnea and hyperventilation were seen after OA while bradypnea and hypoventilation were seen after MBT venom. Pulmonary edema was absent in vagotomised animals in MBT venom group but not in OA group. Further, electrical stimulation of the cut peripheral ends of vagii prolonged the survival time and attenuated all the parameters of MBT venom-induced ARDS significantly. In case of OA, there was improvement in histopathological changes but the survival time of animals was not prolonged. Stimulation of α7-nicotinic receptors (by pretreatment with GTS-21) exacerbated OA as well as MBT venom-induced ARDS. The present results indicate that vagal efferent stimulation protects against MBT venom-induced ARDS. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Taste cell responses in the frog are modulated by parasympathetic efferent nerve fibers.

    PubMed

    Sato, Toshihide; Okada, Yukio; Miyazaki, Toshihiro; Kato, Yuzo; Toda, Kazuo

    2005-11-01

    We studied the anatomical properties of parasympathetic postganglionic neurons in the frog tongue and their modulatory effects on taste cell responses. Most of the parasympathetic ganglion cell bodies in the tongue were found in extremely small nerve bundles running near the fungiform papillae, which originate from the lingual branches of the glossopharyngeal (GP) nerve. The density of parasympathetic postganglionic neurons in the tongue was 8000-11,000/mm(3) of the extremely small nerve bundle. The mean major axis of parasympathetic ganglion cell bodies was 21 microm, and the mean length of parasympathetic postganglionic neurons was 1.45 mm. Electrical stimulation at 30 Hz of either the GP nerve or the papillary nerve produced slow hyperpolarizing potentials (HPs) in taste cells. After nicotinic acetyl choline receptors on the parasympathetic ganglion cells in the tongue had been blocked by intravenous (i.v.) injection of D-tubocurarine (1 mg/kg), stimulation of the GP nerve did not induce any slow HPs in taste cells but that of the papillary nerve did. A further i.v. injection of a substance P NK-1 antagonist, L-703,606, blocked the slow HPs induced by the papillary nerve stimulation. This suggests that the parasympathetic postganglionic efferent fibers innervate taste cells and are related to a generation of the slow HPs and that substance P is released from the parasympathetic postganglionic axon terminals. When the resting membrane potential of a taste cell was hyperpolarized by a prolonged slow HP, the gustatory receptor potentials for NaCl and sugar stimuli were enhanced in amplitude, but those for quinine-HCl and acetic acid stimuli remained unchanged. It is concluded that frog taste cell responses are modulated by activities of parasympathetic postganglionic efferent fibers innervating these cells.

  19. 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.

  20. The effects of callosal agenesis on the susceptibility to seizures elicited by pentylenetetrazol in BALB/cCF mice.

    PubMed

    Medina, Alexandre E; Manhães, Alex C; Schmidt, Sergio L

    2002-01-01

    The effects of callosal agenesis in sensitivity to pentylenetetrazol (PTZ) were studied in 199 (95 males and 104 females) mice of the BALB/cCF strain. This strain presents agenesis of the corpus callosum (CC) in approximately 30% of its population. Seizures were elicited by intraperitoneally injected PTZ. Animals were tested with doses of 40 and 50 mg/kg. Seizure severity was expressed by the following scoring scale: 0 (no abnormal behavior, NAB); 1 (myoclonus, M); 2 (running bouncing clonus, RBC); 3 (tonic hindlimb extension, THE). For the 40-mg/kg dose, abnormal mice were found to be more susceptible, displaying more severe seizures more often then normal mice. Normal female mice were also more susceptible to PTZ than males for this dose. No significant differences were found for the 50-mg/kg dose as a result of the fact that most animals displayed RBC. These data indicate that callosal development and sex are important factors affecting seizure susceptibility.

  1. Developmental Regulation of the (1,3)-beta-Glucan (Callose) Synthase from Tomato : Possible Role of Endogenous Phospholipases.

    PubMed

    Ma, S; Gross, K C; Wasserman, B P

    1991-06-01

    Activity levels of UDP-glucose: (1,3)-beta-glucan (callose) synthase in microsomal membranes of pericarp tissue from tomato fruit (Lycoperisicon esculentum Mill, cv Rutgers) were determined during development and ripening. Addition of the phospholipase inhibitors O-phosphorylcholine and glycerol-1-phosphate to homogenization buffers was necessary to preserve enzyme activity during homogenization and membrane isolation. Enzyme activity declined 90% from the immature green to the red ripe stage. The polypeptide composition of the membranes did not change significantly during ripening. The enzyme from immature fruit was inactivated by exogenously added phospholipases A(2), C, and D. These results suggest that the decline in callose synthase activity during ontogeny may be a secondary effect of endogenous lipase action.

  2. Development of the Corticospinal and Callosal Tracts from Extremely Premature Birth up to 2 Years of Age.

    PubMed

    Braga, Rodrigo M; Roze, Elise; Ball, Gareth; Merchant, Nazakat; Tusor, Nora; Arichi, Tomoki; Edwards, David; Rueckert, Daniel; Counsell, Serena J

    2015-01-01

    White matter tracts mature asymmetrically during development, and this development can be studied using diffusion magnetic resonance imaging. The aims of this study were i. to generate dynamic population-averaged white matter registration templates covering in detail the period from 25 weeks gestational age to term, and extending to 2 years of age based on DTI and fractional anisotropy, ii. to produce tract-specific probability maps of the corticospinal tracts, forceps major and forceps minor using probabilistic tractography, and iii. to assess the development of these tracts throughout this critical period of neurodevelopment. We found evidence for asymmetric development across the fiber bundles studied, with the corticospinal tracts showing earlier maturation (as measured by fractional anisotropy) but slower volumetric growth compared to the callosal fibers. We also found evidence for an anterior to posterior gradient in white matter microstructure development (as measured by mean diffusivity) in the callosal fibers, with the posterior forceps major developing at a faster rate than the anterior forceps minor in this age range. Finally, we report a protocol for delineating callosal and corticospinal fibers in extremely premature cohorts, and make available population-averaged registration templates and a probabilistic tract atlas which we hope will be useful for future neonatal and infant white-matter imaging studies.

  3. Revisiting a study of callosal apraxia: the right hemisphere can imitate the orientation but not the position of the hand.

    PubMed

    Petreska, Biljana; Billard, Aude; Hermsdörfer, Joachim; Goldenberg, Georg

    2010-07-01

    Callosal disconnection can reveal asymmetrical contributions of the two brain hemispheres to praxis. In this paper, we revisit a study of a patient with callosal disconnection (Goldenberg et al., 2001, Neuropsychologia, 39:1432-1443), who perfectly imitated meaningless gestures when imitation was controlled only by the left hemisphere, but was severely impaired when the right hemisphere was in charge of motor control. We decomposed the gestures into a set of geometric variables that were to be reproduced, such as the orientation of the hand and the position of contact between the hand and the face. Whereas orientation of the hand in extrinsic coordinates was replicated correctly by both hemispheres, only the left hemisphere reproduced correctly the position of contact between the hand and the face. This goal-dissociation as well as several partial perseveration errors speak against the hypothesis of a direct route from perception to motor replication of gestures, as interruption of a direct route would probably impair all the features of the gesture. We speculate that incorrect coordination between the reproductions of multiple goals may be the core deficit underlying callosal apraxia. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  4. Interhemispheric communication is via direct connections.

    PubMed

    Collins, M; Coney, J

    1998-08-01

    Two priming experiments, using normal university students as subjects, independently projected low imagery primes and concrete target words to the left or right visual fields (LVF or RVF) to examine the merits of three spreading activation models of interhemispheric communication: (i) callosal relay of a semantically encoded prime; (ii) transfer of products activated as a result of the spread of activation; and (iii) direct connections between the hemispheres. The first experiment temporally separated pairs by a stimulus onset asynchrony (SOA) of 250 ms and obtained strong support for the direct connections model. Priming effects were obtained only when the prime was projected to the RVF and the target to the LVF. The pattern of priming effects suggested that low imagery words projected to the left hemisphere can activate concrete associates in the right hemisphere via direct callosal connections between the two. In the second experiment, the SOA was increased to 450 ms. This time, RVF-RVF priming was obtained along with RVF-LVF priming. The findings are interpreted within a modification of Bleasdale's (1987) framework, where abstract/low imagery words and concrete/high imagery words are represented in separate subsystems in the left hemisphere lexicon. Support was also found for the view that the left hemisphere is comprised of a complex network of abstract and concrete words, while the right hemisphere operates as a subsidiary word processor, subserving linguistic processing with a limited, special purpose lexicon comprised of associative connections between concrete, imageable words (e.g., Zaidel, 1983a; Bradshaw, 1980). Interhemispheric communication in the priming procedure appears to occur at the semantic level, via direct connections between the hemispheres. Copyright 1998 Academic Press.

  5. Debridement of plantar callosities in rheumatoid arthritis: a randomized controlled trial.

    PubMed

    Davys, H J; Turner, D E; Helliwell, P S; Conaghan, P G; Emery, P; Woodburn, J

    2005-02-01

    To compare forefoot pain, pressure and function before and after normal and sham callus treatment in rheumatoid arthritis (RA). Thirty-eight RA patients were randomly assigned to normal (NCT group) or sham (SCT) scalpel debridement. The sham procedure comprised blunt-edged scalpel paring of the callus which delivered a physical stimulus but left the hyperkeratotic tissue intact, the procedure being partially obscured from the patient. Forefoot pain was assessed using a 100 mm visual analogue scale (VAS), pressure using a high-resolution foot pressure scanner and function using the spatial-temporal gait parameters measured on an instrumented walkway. Radiographic scores of joint erosion were obtained for metatarsophalangeal (MTP) joints with and without overlying callosities. The trial consisted of a randomized sham-controlled phase evaluating the immediate same-day treatment effect and an unblinded 4-week follow-up phase. During the sham-controlled phase, forefoot pain improved in both groups by only 3 points on a VAS and no statistically significant between-group difference was found (P = 0.48). When data were pooled during the unblinded phase, the improvement in forefoot pain reached a peak after 2 days and gradually lessened over the next 28 days. Following debridement, peak pressures at the callus sites decreased in the NCT group and increased in the SCT group, but there was no statistically significant between-group difference (P = 0.16). The area of and duration of contact of the callus site on the ground remained unchanged following treatment in both groups. Following debridement, walking speed was increased, the stride-length was longer and the double-support time shorter in both groups; however, between-group differences did not reach levels of statistical significance. MTP joints with overlying callus were significantly more eroded than those without (P = 0.02). Treatment of painful plantar callosities in RA using scalpel debridement lessened forefoot

  6. Neural regulation of inflammation: no neural connection from the vagus to splenic sympathetic neurons.

    PubMed

    Bratton, B O; Martelli, D; McKinley, M J; Trevaks, D; Anderson, C R; McAllen, R M

    2012-11-01

    The 'inflammatory reflex' acts through efferent neural connections from the central nervous system to lymphoid organs, particularly the spleen, that suppress the production of inflammatory cytokines. Stimulation of the efferent vagus has been shown to suppress inflammation in a manner dependent on the spleen and splenic nerves. The vagus does not innervate the spleen, so a synaptic connection from vagal preganglionic neurons to splenic sympathetic postganglionic neurons was suggested. We tested this idea in rats. In a preparatory operation, the anterograde tracer DiI was injected bilaterally into the dorsal motor nucleus of vagus and the retrograde tracer Fast Blue was injected into the spleen. On histological analysis 7-9 weeks later, 883 neurons were retrogradely labelled from the spleen with Fast Blue as follows: 89% in the suprarenal ganglia (65% left, 24% right); 11% in the left coeliac ganglion; but none in the right coeliac or either of the superior mesenteric ganglia. Vagal terminals anterogradely labelled with DiI were common in the coeliac but sparse in the suprarenal ganglia, and confocal analysis revealed no putative synaptic connection with any Fast Blue-labelled cell in either ganglion. Electrophysiological experiments in anaesthetized rats revealed no effect of vagal efferent stimulation on splenic nerve activity or on that of 15 single splenic-projecting neurons recorded in the suprarenal ganglion. Together, these findings indicate that vagal efferent neurons in the rat neither synapse with splenic sympathetic neurons nor drive their ongoing activity.

  7. Efferents and afferents in an intact muscle nerve: background activity and effects of sural nerve stimulation in the cat.

    PubMed

    Bessou, P; Joffroy, M; Pagès, B

    1981-11-01

    1. The background activity was observed in gamma and alpha efferent fibres and in group I and II fibres innervating the muscle gastrocnemius lateralis or medialis. The reflex effects of ipsilateral and contralateral sural nerve stimulations on the muscle efferents were analysed together with their consequences upon the afferents of the same muscle. The observations were made in the decerebrated cat without opening the neural loops between the muscle and the spinal cord.2. The multi-unit discharges of each category of fibres were obtained, on line, by an original electronic device (Joffroy, 1975, 1980) that sorted the action potentials from the whole electrical activity of a small branch of gastrocnemius lateralis or medialis nerve according to the direction and velocity of propagation of the potentials.3. The small nerve may be regarded as a representative sample of different functional groups of fibres conducting faster than 12 m.sec(-1) and supplying gastrocnemius muscles.4. Some gamma efferents were always tonically firing except when a transient flaccid state developed. Usually the alpha efferents were silent, probably because the muscle was fixed close to the minimal physiological length.5. Separate and selective stimulations of Abeta, Adelta and C fibres of ipsilateral and contralateral sural nerve showed that each group could induce the excitation of gamma neurones. The reciprocal inhibition period of alpha efferents during a flexor reflex was only once accompanied by a small decrease in gamma-firing.6. The reflex increase of over-all frequency of gamma efferents resulted from an increased firing rate of tonic gamma neurones and from the recruitment of gamma neurones previously silent. When the gamma efferents in the small nerve naturally occurred in two subgroups, the slower-conducting subgroup (mainly composed of tonic gamma axons) was activated before the faster-conducting subgroup (mostly composed by gamma axons with no background discharge). Some rare

  8. Subcortical connections of area V4 in the macaque

    PubMed Central

    Gattass, Ricardo; Galkin, Thelma W; Desimone, Robert; Ungerleider, Leslie G

    2014-01-01

    Area V4 has numerous, topographically organized connections with multiple cortical areas, some of which are important for spatially organized visual processing, and others which seem important for spatial attention. Although the topographic organization of V4’s connections with other cortical areas has been established, the detailed topography of its connections with subcortical areas is unclear. We therefore injected retrograde and anterograde tracers in different topographical regions of V4 in nine macaques to determine the organization of its subcortical connections. The injection sites included representations ranging from the fovea to far peripheral eccentricities in both the upper and lower visual fields. The topographically organized connections of V4 included bidirectional connections with four subdivisions of the pulvinar, two subdivisions of the claustrum, and the interlaminar portions of the lateral geniculate nucleus, and efferent projections to the superficial and intermediate layers of the superior colliculus, the thalamic reticular nucleus, and the caudate nucleus. All of these structures have a possible role in spatial attention. The nontopographic, or converging, connections included bidirectional connections with the lateral nucleus of the amygdala, afferent inputs from the dorsal raphe, median raphe, locus coeruleus, ventral tegmentum and nucleus basalis of Meynert, and efferent projections to the putamen. Any role of these structures in attention may be less spatially specific. J. Comp. Neurol. 522:1941–1965, 2014. PMID:24288173

  9. Differential Effects of Brain Disorders on Structural and Functional Connectivity.

    PubMed

    Vega-Pons, Sandro; Olivetti, Emanuele; Avesani, Paolo; Dodero, Luca; Gozzi, Alessandro; Bifone, Angelo

    2016-01-01

    Different measures of brain connectivity can be defined based on neuroimaging read-outs, including structural and functional connectivity. Neurological and psychiatric conditions are often associated with abnormal connectivity, but comparing the effects of the disease on different types of connectivity remains a challenge. In this paper, we address the problem of quantifying the relative effects of brain disease on structural and functional connectivity at a group level. Within the framework of a graph representation of connectivity, we introduce a kernel two-sample test as an effective method to assess the difference between the patients and control group. Moreover, we propose a common representation space for structural and functional connectivity networks, and a novel test statistics to quantitatively assess differential effects of the disease on different types of connectivity. We apply this approach to a dataset from BTBR mice, a murine model of Agenesis of the Corpus Callosum (ACC), a congenital disorder characterized by the absence of the main bundle of fibers connecting the two hemispheres. We used normo-callosal mice (B6) as a comparator. The application of the proposed methods to this data-set shows that the two types of connectivity can be successfully used to discriminate between BTBR and B6, meaning that both types of connectivity are affected by ACC. However, our novel test statistics shows that structural connectivity is significantly more affected than functional connectivity, consistent with the idea that functional connectivity has a robust topology that can tolerate substantial alterations in its structural connectivity substrate.

  10. Differential Effects of Brain Disorders on Structural and Functional Connectivity

    PubMed Central

    Vega-Pons, Sandro; Olivetti, Emanuele; Avesani, Paolo; Dodero, Luca; Gozzi, Alessandro; Bifone, Angelo

    2017-01-01

    Different measures of brain connectivity can be defined based on neuroimaging read-outs, including structural and functional connectivity. Neurological and psychiatric conditions are often associated with abnormal connectivity, but comparing the effects of the disease on different types of connectivity remains a challenge. In this paper, we address the problem of quantifying the relative effects of brain disease on structural and functional connectivity at a group level. Within the framework of a graph representation of connectivity, we introduce a kernel two-sample test as an effective method to assess the difference between the patients and control group. Moreover, we propose a common representation space for structural and functional connectivity networks, and a novel test statistics to quantitatively assess differential effects of the disease on different types of connectivity. We apply this approach to a dataset from BTBR mice, a murine model of Agenesis of the Corpus Callosum (ACC), a congenital disorder characterized by the absence of the main bundle of fibers connecting the two hemispheres. We used normo-callosal mice (B6) as a comparator. The application of the proposed methods to this data-set shows that the two types of connectivity can be successfully used to discriminate between BTBR and B6, meaning that both types of connectivity are affected by ACC. However, our novel test statistics shows that structural connectivity is significantly more affected than functional connectivity, consistent with the idea that functional connectivity has a robust topology that can tolerate substantial alterations in its structural connectivity substrate. PMID:28119556

  11. Why size matters: differences in brain volume account for apparent sex differences in callosal anatomy: the sexual dimorphism of the corpus callosum.

    PubMed

    Luders, Eileen; Toga, Arthur W; Thompson, Paul M

    2014-01-01

    Numerous studies have demonstrated a sexual dimorphism of the human corpus callosum. However, the question remains if sex differences in brain size, which typically is larger in men than in women, or biological sex per se account for the apparent sex differences in callosal morphology. Comparing callosal dimensions between men and women matched for overall brain size may clarify the true contribution of biological sex, as any observed group difference should indicate pure sex effects. We thus examined callosal morphology in 24 male and 24 female brains carefully matched for overall size. In addition, we selected 24 extremely large male brains and 24 extremely small female brains to explore if observed sex effects might vary depending on the degree to which male and female groups differed in brain size. Using the individual T1-weighted brain images (n=96), we delineated the corpus callosum at midline and applied a well-validated surface-based mesh-modeling approach to compare callosal thickness at 100 equidistant points between groups determined by brain size and sex. The corpus callosum was always thicker in men than in women. However, this callosal sex difference was strongly determined by the cerebral sex difference overall. That is, the larger the discrepancy in brain size between men and women, the more pronounced the sex difference in callosal thickness, with hardly any callosal differences remaining between brain-size matched men and women. Altogether, these findings suggest that individual differences in brain size account for apparent sex differences in the anatomy of the corpus callosum.

  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. Paralinguistic processing in children with callosal agenesis: emergence of neurolinguistic deficits.

    PubMed

    Brown, Warren S; Symingtion, Melissa; VanLancker-Sidtis, Diana; Dietrich, Rosalind; Paul, Lynn K

    2005-05-01

    Recent research revealed impaired processing of both nonliteral meaning and affective prosody in adults with agenesis of the corpus callosum (ACC) and normal intelligence. Since normal children have incomplete myelination of the corpus callosum, it was hypothesized that paralanguage deficits in children with ACC would be less apparent relative to their peers. The Familiar and Novel Language Comprehension Test (FANL-C) and Prosody Test were given to 18 children with ACC and normal intelligence and 17 controls matched for age (7-13 years), education, and IQ (83-122). When controlling for age, children with ACC were significantly poorer in comprehension of the precise meaning of both literal and nonliteral items on the FANL-C. Adults with ACC had previously been shown to have difficulty only on nonliteral items. The effect size for nonliteral comprehension in children with ACC was smaller than that seen in adults. There was only a trend for the child ACC group to perform worse on the recognition of affective prosody. Thus, while deficits in paralinguistic processing were apparent, children with ACC were not as clearly different from age peers as adults, and were equally deficient at comprehending literal and nonliteral expressions. The differences in results between adults and children with ACC are thought to reflect incomplete callosal development in normal children, and the importance of the corpus callosum in the early stages of the development of the ability to process literal language.

  14. Genetic and functional analyses identify DISC1 as a novel callosal agenesis candidate gene.

    PubMed

    Osbun, Nathan; Li, Jiang; O'Driscoll, Mary C; Strominger, Zoe; Wakahiro, Mari; Rider, Eric; Bukshpun, Polina; Boland, Elena; Spurrell, Cailyn H; Schackwitz, Wendy; Pennacchio, Len A; Dobyns, William B; Black, Graeme C M; Sherr, Elliott H

    2011-08-01

    Agenesis of the corpus callosum (AgCC) is a congenital brain malformation that occurs in approximately 1:1,000-1:6,000 births. Several syndromes associated with AgCC have been traced to single gene mutations; however, the majority of AgCC causes remain unidentified. We investigated a mother and two children who all shared complete AgCC and a chromosomal deletion at 1q42. We fine mapped this deletion and show that it includes Disrupted-in-Schizophrenia 1 (DISC1), a gene implicated in schizophrenia and other psychiatric disorders. Furthermore, we report a de novo chromosomal deletion at 1q42.13 to q44, which includes DISC1, in another individual with AgCC. We resequenced DISC1 in a cohort of 144 well-characterized AgCC individuals and identified 20 sequence changes, of which 4 are rare potentially pathogenic variants. Two of these variants were undetected in 768 control chromosomes. One of these is a splice site mutation at the 5' boundary of exon 11 that dramatically reduces full-length mRNA expression of DISC1, but not of shorter forms. We investigated the developmental expression of mouse DISC1 and find that it is highly expressed in the embryonic corpus callosum at a critical time for callosal formation. Taken together our results suggest a significant role for DISC1 in corpus callosum development.

  15. 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.

  16. Lifelong strength training mitigates the age-related decline in efferent drive.

    PubMed

    Unhjem, Runar; Nygård, Mona; van den Hoven, Lene T; Sidhu, Simranjit K; Hoff, Jan; Wang, Eivind

    Recently, we documented age-related attenuation of efferent drive to contracting skeletal muscle. It remains elusive if this indication of reduced muscle strength is present with lifelong strength training. For this purpose, we examined evoked potentials in the calf muscles of 11 [71 ± 4 (SD) yr] strength-trained master athletes (MA) contrasted with 10 (71 ± 4 yr) sedentary (SO) and 11 (73 ± 6 yr) recreationally active (AO) old subjects, as well as 9 (22 ± 2 yr) young controls. As expected, MA had higher leg press maximal strength (MA, 185 ± 32 kg; AO, 128 ± 15 kg; SO, 106 ± 11 kg; young, 147 ± 22 kg, P < 0.01) and rate of force development (MA, 5,588 ± 2,488 N/s; AO, 2,156 ± 1,100 N/s; SO, 2,011 ± 825 N/s; young, 3,663 ± 1,140 N/s, P < 0.05) than the other groups. MA also exhibited higher musculus soleus normalized V waves during maximal voluntary contractions (MVC) [maximal V wave amplitude/maximal M wave during MVC (Vsup/Msup); 0.28 ± 0.15] than AO (0.13 ± 0.06, P < 0.01) and SO (0.11 ± 0.05, P < 0.01), yet lower than young (0.45 ± 0.12, P < 0.01). No differences were apparent between the old groups in H reflex recorded at rest or during MVC [maximal H reflex amplitude/maximal M wave during rest (Hmax/Mmax); maximal H reflex amplitude during MVC/maximal M wave during MVC (Hsup/Msup)], and all were lower (P < 0.01) than young. MA (34.4 ± 2.1 ms) had shorter (P < 0.05) H reflex latency compared with AO (36.4 ± 3.7 ms) and SO (37.3 ± 3.2 ms), but longer (P < 0.01) than young (30.7 ± 2.0 ms). Using interpolated twitch analysis, MA (89 ± 7%) had plantar flexion voluntary activation similar to young (90 ± 6%), and this was higher (P < 0.05), or tended to be higher (P = 0.06-0.09), than SO (83 ± 10%) and AO (84 ± 5%). These observations suggest that lifelong strength training has a protective effect against age-related attenuation of efferent drive. In contrast, no beneficial effect seems to derive from habitual recreational activity, indicating

  17. [Readjustment of the efferent activity of the scratching generator in response to stimulation of cutaneous afferents of the hindlimb of the decerebrate immobilized cat].

    PubMed

    Shimanskiĭ, Iu P; Baev, K V

    1987-01-01

    Rebuildings of the scratching generator efferent activity caused by the phasic electrical stimulation of ipsilateral hindlimb skin nerves during different hindlimb positions were studied in decerebrated immobilized cats. Stimulation was followed by short latency inhibition of the efferent activity. Stimulation did not cause correlation shifts in the common "aiming" and "scratching" activity. Changes in the efferent activity cycle duration and intensity depended on the stimulation phase. Inversion of intensity changes occurred with transition from the middle-force to strong stimulation. A functional role of the dependence of the efferent activity rebuilding on the stimulation phase is considered. The scratching generator is supposed to contain a model of the afferent inflow which enters the spinal cord during real scratching.

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

    PubMed Central

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

    2015-01-01

    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. PMID:25582052

  19. 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.

  20. Efferent projections of nucleus locus coeruleus: topographic organization of cells of origin demonstrated by three-dimensional reconstruction.

    PubMed

    Loughlin, S E; Foote, S L; Bloom, F E

    1986-06-01

    The present study examines the spatial distribution within rat locus coeruleus of neurons projecting to particular brain regions. In order to accurately recreate, in digital and pictorial formats, the spatial distribution of neurons for the entire nucleus locus coeruleus, three-dimensional reconstructions were created which specified the location of each individual Nissl-stained locus coeruleus cell in each of five nuclei. Dynamic computerized displays were visually analyzed and statistically compared. The nuclei from different brains were found to be strikingly similar in density and distribution of cells. In order to determine whether the cells of origin for particular locus coeruleus projections were clustered within the nucleus, reconstructions were created of the distributions of cells labeled by injections of a retrograde tracer, horseradish peroxidase, into particular terminal regions. Groups consisting of animals with injections into the same target areas were visually and statistically compared. The cells of origin of most efferent projections were found to be spatially organized within locus coeruleus. Specifically, projections to both the dorsal and ventral hippocampus originated solely from the dorsal segment of the nucleus, while spinal cord projections originated from ventral-posterior locus coeruleus. Cells of origin of cerebral and cerebellar cortical efferents, as well as hypothalamic efferents, exhibited less clustering, although reliable differences in distribution were observed. The most striking example of clustered cells of origin was exhibited by the large norepinephrine-containing cells constituting the anterior pole of locus coeruleus which were labeled only by hypothalamic injections. This analysis of spatial organization within locus coeruleus is unique in its utilization of a defined control group, experimental groups consisting of strictly defined replications, accurate three-dimensional reconstruction, and statistical comparisons. The

  1. 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

  2. The importance of mammillary body efferents for recency memory: towards a better understanding of diencephalic amnesia.

    PubMed

    Nelson, Andrew J D; Vann, Seralynne D

    2017-07-01

    Despite being historically one of the first brain regions linked to memory loss, there remains controversy over the core features of diencephalic amnesia as well as the critical site for amnesia to occur. The mammillary bodies and thalamus appear to be the primary locus of pathology in the cases of diencephalic amnesia, but the picture is complicated by the lack of patients with circumscribed damage. Impaired temporal memory is a consistent neuropsychological finding in Korsakoff syndrome patients, but again, it is unclear whether this deficit is attributable to pathology within the diencephalon or concomitant frontal lobe dysfunction. To address these issues, we used an animal model of diencephalic amnesia and examined the effect of mammillothalamic tract lesions on tests of recency memory. The mammillothalamic tract lesions severely disrupted recency judgements involving multiple items but left intact both recency and familiarity judgements for single items. Subsequently, we used disconnection procedures to assess whether this deficit reflects the indirect involvement of the prefrontal cortex. Crossed-lesion rats, with unilateral lesions of the mammillothalamic tract and medial prefrontal cortex in contralateral hemispheres, were unimpaired on the same recency tests. These results provide the first evidence for the selective importance of mammillary body efferents for recency memory. Moreover, this contribution to recency memory is independent of the prefrontal cortex. More broadly, these findings identify how specific diencephalic structures are vital for key elements of event memory.

  3. Roles of the Contralateral Efferent Reflex in Hearing Demonstrated with Cochlear Implants.

    PubMed

    Lopez-Poveda, Enrique A; Eustaquio-Martín, Almudena; Stohl, Joshua S; Wolford, Robert D; Schatzer, Reinhold; Wilson, Blake S

    2016-01-01

    Our two ears do not function as fixed and independent sound receptors; their functioning is coupled and dynamically adjusted via the contralateral medial olivocochlear efferent reflex (MOCR). The MOCR possibly facilitates speech recognition in noisy environments. Such a role, however, is yet to be demonstrated because selective deactivation of the reflex during natural acoustic listening has not been possible for human subjects up until now. Here, we propose that this and other roles of the MOCR may be elucidated using the unique stimulus controls provided by cochlear implants (CIs). Pairs of sound processors were constructed to mimic or not mimic the effects of the contralateral MOCR with CIs. For the non-mimicking condition (STD strategy), the two processors in a pair functioned independently of each other. When configured to mimic the effects of the MOCR (MOC strategy), however, the two processors communicated with each other and the amount of compression in a given frequency channel of each processor in the pair decreased with increases in the output energy from the contralateral processor. The analysis of output signals from the STD and MOC strategies suggests that in natural binaural listening, the MOCR possibly causes a small reduction of audibility but enhances frequency-specific inter-aural level differences and the segregation of spatially non-overlapping sound sources. The proposed MOC strategy could improve the performance of CI and hearing-aid users.

  4. Efferent Feedback in a Spinal-Like Controller: Reaching With Perturbations.

    PubMed

    Stefanovic, Filip; Galiana, Henrietta L

    2016-01-01

    We use simulations of a controller that adopts a spinal-like network topology for goal-oriented reaching and assess its sensitivity to the dynamics of internal elements that allow context-independent performance. Such internal elements are often referred to as inverse or forward models of the periphery dynamics, depending on the proposed controller theory. Here, the "models" are used in a forward implementation, and we evaluate how the controller's performance would be affected by the nature of the model. For each point-to-point reaching motion experiment, we use forms of internal "efference models" (e.g., full mathematical representations of peripheral dynamics, simple spindle feedback, etc.) driven by motor reafference, then compare hand trajectories and hand path speeds in the presence or absence of external perturbations. It is demonstrated that a simple velocity-based model reduced the effects of dynamic perturbations by as much as 66%. In addition, the 2D hand trajectories varied from a biological reference by only 0.05 cm. Thus, the controller facilitated biological like motions while providing response to dynamic events which are omitted in earlier biomimetic controllers. This research suggests that these spinal-like systems are robust and tunable via gain-fields without the need of context dependent pre-planning.

  5. Tonic efferent-induced cochlear damping in roosting and echolocating mustached bats.

    PubMed

    Xie, D H; Henson, O W

    1998-10-01

    The activity of the medial olivocochlear (MOC) efferent system in mustached bats, Pteronotus p. parnellii, was studied by monitoring changes in the mechanical properties of the cochlea. The changing properties were expressed by the decay time (DT) of cochlear microphonic potentials produced by transient-induced ringing (Henson et al., 1995). Tape-recorded roost noise (biosonar and communication sounds) produced sudden, marked decreases in DT when presented to the contralateral ear of animals adapted to the quiet. When the animals were first removed from their roosts the DT was relatively short (1.2-1.5 ms) but this gradually lengthened by about 0.5-1.0 ms as they rested in a quiet chamber. The time required to reach a stable, quiet-adapted state after noise exposure varied with SPL and exposure time; in many experiments recovery was in the range of 90-120 min. When quiet-adapted bats were isolated and allowed to fly and echolocate for 20 min, the DTs measured within a few minutes after the end of the flight were also short and only slowly returned to longer preflight values. The administration of a single dose of gentamicin, which blocks MOC effects, greatly reduced the amount of suppression (damping) observed after periods of noise and echolocation sound exposure. We conclude that tonic MOC activity is induced by the natural vocalizations and roost noise and this activity probably regulates and protects the highly resonant cochlear partition.

  6. Efferent projections of the dorsal ventricular ridge and the striatum in the Tegu lizard. Tupinambis nigropunctatus.

    PubMed

    Voneida, T J; Sligar, C M

    1979-07-01

    A H3 proline-leucine mixture was injected into the dorsal ventricular ridge (DVR) and striatum of the Tegu lizard in order to determine their efferent projections. The brains were processed according to standard radioautographic technique, and counterstained with cresyl violet. DVR projections were generally restricted to the telencephalon, while striatal projections were limited to diencephalic and mesencephalic structures. Thus the anterior DVR projects ipsilaterally to nuclei sphericus and lateralis amygdalae, striatum (ipsilateral and contralateral) ventromedial nucleus of the hypothalamus, nucleus accumbens, anterior olfactory nucleus, nucleus of the lateral olfactory tract and lateral pallium. Posterior DVR projections enter ipsilateral anterior olfactory nucleus, lateral and interstitial amygdalar nuclei, olfactory tubercle and bulb, nucleus of the lateral olfactory tract and a zone surrounding the ventromedial hypothalamic nucleus. Labeled axons from striatal injections pass caudally in the lateral forebrain bundle to enter (via dorsal peduncle) nuclei dorsomedialis, medialis posterior, entopeduncularis anterior, and a zone surrounding nucleus rotundus. Others join the ventral peduncle of LFB and enter ventromedial nucleus (thalami), while the remaining fibers continue caudally in the ventral peduncle to the mesencephalic prerubral field, central gray, substantia nigra, nucleus intercollicularis, reticular formation and pretectal nucleus posterodorsalis. These results are discussed in relation to the changing notions regarding terminology, classification and functions of dorsl ventricular ridge and striatum.

  7. Olivocochlear Efferent Control in Sound Localization and Experience-Dependent Learning

    PubMed Central

    Irving, Samuel; Moore, David R.; Liberman, M. Charles; Sumner, Christian J.

    2012-01-01

    Efferent auditory pathways have been implicated in sound localization and its plasticity. We examined the role of the olivocochlear system (OC) in horizontal sound localization by the ferret and in localization learning following unilateral earplugging. Under anesthesia, adult ferrets underwent olivocochlear bundle section at the floor of the fourth ventricle, either at the midline or laterally (left). Lesioned and control animals were trained to localize 1 s and 40ms amplitude-roved broadband noise stimuli from one of 12 loudspeakers. Neither type of lesion affected normal localization accuracy. All ferrets then received a left earplug and were tested and trained over 10 d. The plug profoundly disrupted localization. Ferrets in the control and lateral lesion groups improved significantly during subsequent training on the 1 s stimulus. No improvement (learning) occurred in the midline lesion group. Markedly poorer performance and failure to learn was observed with the 40 ms stimulus in all groups. Plug removal resulted in a rapid resumption of normal localization in all animals. Insertion of a subsequent plug in the right ear produced similar results to left earplugging. Learning in the lateral lesion group was independent of the side of the lesion relative to the earplug. Lesions in all reported cases were verified histologically. The results suggest the OC system is not needed for accurate localization, but that it is involved in relearning localization during unilateral conductive hearing loss. PMID:21325517

  8. Uroguanylin Action in the Brain Reduces Weight Gain in Obese Mice via Different Efferent Autonomic Pathways.

    PubMed

    Folgueira, Cintia; Beiroa, Daniel; Callon, Aurelie; Al-Massadi, Omar; Barja-Fernandez, Silvia; Senra, Ana; Fernø, Johan; López, Miguel; Dieguez, Carlos; Casanueva, Felipe F; Rohner-Jeanrenaud, Françoise; Seoane, Luisa M; Nogueiras, Ruben

    2016-02-01

    The gut-brain axis is of great importance in the control of energy homeostasis. The identification of uroguanylin (UGN), a peptide released in the intestines that is regulated by nutritional status and anorectic actions, as the endogenous ligand for the guanylyl cyclase 2C receptor has revealed a new system in the regulation of energy balance. We show that chronic central infusion of UGN reduces weight gain and adiposity in diet-induced obese mice. These effects were independent of food intake and involved specific efferent autonomic pathways. On one hand, brain UGN induces brown adipose tissue thermogenesis, as well as browning and lipid mobilization in white adipose tissue through stimulation of the sympathetic nervous system. On the other hand, brain UGN augments fecal output through the vagus nerve. These findings are of relevance as they suggest that the beneficial metabolic actions of UGN through the sympathetic nervous system do not involve nondesirable gastrointestinal adverse effects, such as diarrhea. The present work provides mechanistic insights into how UGN influences energy homeostasis and suggests that UGN action in the brain represents a feasible pharmacological target in the treatment of obesity. © 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  9. Afferent and Efferent Aspects of Mandibular Sensorimotor Control in Adults who Stutter

    PubMed Central

    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, we 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 commands. Method We investigated 11 stuttering and 11 nonstuttering adults’ kinesthetic sensitivity threshold and kinesthetic accuracy for passive jaw movements as well as their minimal displacement threshold and positioning accuracy for active jaw movements. We also investigated the correlation with an anatomical index of jaw size. Results The groups showed no statistically significant differences on sensory measures for passive jaw movements. Although some stuttering individuals performed more poorly than any nonstuttering participants on the active movement tasks, between-group differences for active movements were also not statistically significant. Unlike fluent speakers, however, the stuttering group showed a statistically significant correlation between mandibular size and performance in the active and passive near-threshold tasks. Conclusions Previously reported minimal movement differences were not replicated. Instead, stuttering individuals’ performance varied with anatomical properties. These correlational results are consistent with the hypothesis that stuttering participants generate and perceive movements based on less accurate internal models of the involved neuromechanical systems. PMID:23816664

  10. 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.

  11. Efferent neurotransmission of circadian rhythms in Limulus lateral eye. I. Octopamine-induced increases in retinal sensitivity.

    PubMed

    Kass, L; Barlow, R B

    1984-04-01

    Octopamine increases the sensitivity of the Limulus lateral eye in situ when injected beneath the cornea during the day. The effect of octopamine is dose-dependent with a threshold concentration of about 0.1 microM injected at 1 microliter/min for 15 min. Injection of 40 microM octopamine increases lateral eye sensitivity to approximately 70% of the nighttime level normally caused by the efferent output of a circadian clock. Injections of octopamine analogues and other candidate neurotransmitters indicate that the postsynaptic receptor mediating the increase of retinal sensitivity is relatively specific for the structure of octopamine. The postsynaptic receptor is tentatively classified as a type 2B octopamine receptor (Evans, P. D. (1981) J. Physiol. (Lond.) 318: 99-122). Clozapine suppresses the effects of both exogenous octopamine and the endogenous efferent neurotransmitter. Together with the results from Barlow et al. (Barlow, R. B., Jr., S. J. Bolanowski, Jr., and M. L. Brachman (1977) Science 197: 86-89) and Battelle et al. (Batelle, B. -A., J. A. Evans, and S. C. Chamberlain (1982) Science 216: 1250-1252) our study leads to the following conclusion: retinal efferents, driven by a circadian clock in Limulus brain, release octopamine that increases visual sensitivity.

  12. Evaluation of the olivocochlear efferent reflex strength in the susceptibility to temporary hearing deterioration after music exposure in young adults.

    PubMed

    Hannah, Keppler; Ingeborg, Dhooge; Leen, Maes; Annelies, Bockstael; Birgit, Philips; Freya, Swinnen; Bart, Vinck

    2014-01-01

    The objective of the current study was to evaluate the predictive role of the olivocochlear efferent reflex strength in temporary hearing deterioration in young adults exposed to music. This was based on the fact that a noise-protective role of the medial olivocochlear (MOC) system was observed in animals and that efferent suppression (ES) measured using contralateral acoustic stimulation (CAS) of otoacoustic emissions (OAEs) is capable of exploring the MOC system. Knowing an individual's susceptibility to cochlear damage after noise exposure would enhance preventive strategies for noise-induced hearing loss. The hearing status of 28 young adults was evaluated using pure-tone audiometry, transient evoked OAEs (TEOAEs) and distortion product OAEs (DPOAEs) before and after listening to music using an MP3 player during 1 h at an individually determined loud listening level. CAS of TEOAEs was measured before music exposure to determine the amount of ES. Regression analysis showed a distinctive positive correlation between temporary hearing deterioration and the preferred gain setting of the MP3 player. However, no clear relationship between temporary hearing deterioration and the amount of ES was found. In conclusion, clinical measurement of ES, using CAS of TEOAEs, is not correlated with the amount of temporary hearing deterioration after 1 h music exposure in young adults. However, it is possible that the temporary hearing deterioration in the current study was insufficient to activate the MOC system. More research regarding ES might provide more insight in the olivocochlear efferent pathways and their role in auditory functioning.

  13. 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.

  14. 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.

  15. Morphological and ultrastructural study of the efferent ductules in the Chinese soft-shelled turtle Pelodiscus sinensis.

    PubMed

    Waqas, Muhammad Yasir; Liu, Tengfei; Yang, Ping; Ahmed, Nisar; Zhang, Qian; Hu, Lisi; Hong, Chen; Chen, Qiusheng

    2016-02-01

    Comparative study of the turtle excurrent duct system increases our understanding the evolution of sperm motility and fertility maintenance in higher vertebrates. Therefore, in this study we observed the histology and ultrastructure organization of efferent ductules in the Pelodiscus sinensis using light and transmission electron microscopy. The efferent ductules are extra- testicular and 22-28 in number originate from rete testis. The epithelium is entirely composed of two types of cells, the predominant non-ciliated and ciliated cells. The ciliated cells have long cilia that protrude into the lumen to form a meshwork. These cells associated with clusters of mitochondria in the supranuclear cytoplasm and possess coated vesicles, vacuole, intracellular spaces, and junction complexes. Ciliated cells in the proximal portion of the ductules contain an endocytic apparatus with coated pits and tubules in the apical cytoplasm. Interdigitations and lipid droplets are predominantly present around the nuclei of these cells. The non-ciliated cells have clusters of mitochondria present in both the supranuclear and perinuclear cytoplasm whereas, the nuclei of these cells are lightly stained. Moreover, the contour of the epithelium towards lumen is irregular as it has a deep indentation. The apical cytoplasm goes deep into the lumen to form cytoplasmic processes. This is the first study to describe the detailed features of efferent ductules in Pelodiscus sinensis with, special focus on the morphology of ciliated cells, as these cells are involved in the mixing of luminal fluid and transport of spermatozoa towards the distal region. © 2015 Wiley Periodicals, Inc.

  16. 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.

  17. Speech-independent production of communicative gestures: evidence from patients with complete callosal disconnection.

    PubMed

    Lausberg, Hedda; Zaidel, Eran; Cruz, Robyn F; Ptito, Alain

    2007-10-01

    Recent neuropsychological, psycholinguistic, and evolutionary theories on language and gesture associate communicative gesture production exclusively with left hemisphere language production. An argument for this approach is the finding that right-handers with left hemisphere language dominance prefer the right hand for communicative gestures. However, several studies have reported distinct patterns of hand preferences for different gesture types, such as deictics, batons, or physiographs, and this calls for an alternative hypothesis. We investigated hand preference and gesture types in spontaneous gesticulation during three semi-standardized interviews of three right-handed patients and one left-handed patient with complete callosal disconnection, all with left hemisphere dominance for praxis. Three of them, with left hemisphere language dominance, exhibited a reliable left-hand preference for spontaneous communicative gestures despite their left hand agraphia and apraxia. The fourth patient, with presumed bihemispheric language representation, revealed a consistent right-hand preference for gestures. All four patients displayed batons, tosses, and shrugs more often with the left hand/shoulder, but exhibited a right hand preference for pantomime gestures. We conclude that the hand preference for certain gesture types cannot be predicted by hemispheric dominance for language or by handedness. We found distinct hand preferences for specific gesture types. This suggests a conceptual specificity of the left and right hand gestures. We propose that left hand gestures are related to specialized right hemisphere functions, such as prosody or emotion, and that they are generated independently of left hemisphere language production. Our findings challenge the traditional neuropsychological and psycholinguistic view on communicative gesture production.

  18. Sex differences in callosal transfer and hemispheric specialization for face coding.

    PubMed

    Proverbio, Alice Mado; Mazzara, Roberta; Riva, Federica; Manfredi, Mirella

    2012-07-01

    Previous studies have shown a reduced lateralization of brain functions in women compared with men. Similarly, some studies have shown that the inter-hemispheric transfer (IHTT) of information is asymmetric in men, with faster latencies in the RH→LH compared with the LH→RH direction, and symmetric in women. The aim of the present study was to investigate IHTT and hemispheric lateralization during face processing in the two sexes. Event-related potentials (ERPs) were recorded in strictly right-handed people (16 men and 17 women) engaged in a face-sex categorization task. Occipital P1 and occipito/temporal N170 were left lateralized in women and bilateral in men. Overall the data suggest a certain involvement of the LH in face feature analysis (possibly related to sex-coding) in both sexes. N170 to contralateral stimuli was larger over the RH in men and the LH in women. IHTT was approximately 4 ms at the P1 level and approximately 8 ms at the N170 level. It was asymmetric in men, with faster latencies in the left visual field (LVF)/RH→LH (170 ms) direction than in the right-visual field (RVF)/LH→RH (185 ms) direction and symmetric in women. These findings suggest that the asymmetry in callosal transfer times might be due to faster transmission times of face-related information via fibers departing from the more efficient to the less efficient hemisphere. Overall, our findings also support the notion that the transfer time of visual inputs might be more rapid and symmetric in women than in men. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

    PubMed Central

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

    2015-01-01

    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. PMID:25428995

  20. Short-term effect of scalpel debridement of plantar callosities versus treatment with salicylic acid patches: The EMEDESCA randomized controlled trial.

    PubMed

    Gijón-Noguerón, Gabriel; García-Paya, Irene; Morales-Asencio, José Miguel; Jiménez-Cebrián, Ana; Ortega-Ávila, Ana Belén; Cervera-Marín, José Antonio

    2017-06-01

    This study compares scalpel debridement versus salicylic acid patches in the treatment of plantar callosities. A randomized clinical trial (ACTRN12614000591651) was performed with 62 patients, divided into two intervention groups. Group A received treatment with salicylic acid patches (Callívoro Marthand(®) ) and group B underwent scalpel debridement of plantar callosities. Pain was measured on a visual analog scale, and foot pain and disability were evaluated using the Manchester Foot Pain Disability Index (MFPDI) questionnaire (Spanish version). Significant differences were observed in pain measured immediately after treatment (P < 0.001) and at 15 days and 6 weeks after treatment. For some components, the MFPDI questionnaire revealed significantly better outcomes by scalpel debridement at 15 days after treatment. The scalpel debridement of plantar callosities relieves pain more effectively than salicylic acid patches, and patients achieve greater functionality in the initial weeks after debridement. © 2016 Japanese Dermatological Association.

  1. Arrangement of fiber tracts forming Probst bundle in complete callosal agenesis: report of two cases with an evaluation by diffusion tensor tractography.

    PubMed

    Utsunomiya, H; Yamashita, S; Takano, K; Okazaki, M

    2006-12-01

    We report two patients with complete callosal agenesis in whom Probst bundles in both hemispheres could be depicted by diffusion tensor tractography (DTT). While one patient had no associated telencephalic anomaly other than callosal agenesis, the other had cortical dysplasia in the right frontal lobe. Although Probst bundles in the three normal hemispheres were well developed, that in the hemisphere which was affected by cortical dysplasia was small and poorly developed. DTT also showed that the fibers from the frontal pole ran more on the inner side of the Probst bundle than those from a more caudal region of the frontal lobe. Furthermore, fibers from the orbital gyri ran along the outermost side of Probst bundle. The arrangement of these fiber tracts in Probst bundle may reflect the developmental process of callosal fibers in their normal formation.

  2. 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.

  3. Frontonasal dysplasia, callosal agenesis, basal encephalocele, and eye anomalies syndrome with a partial 21q22.3 deletion.

    PubMed

    Guion-Almeida, Maria Leine; Richieri-Costa, Antonio; Jehee, Fernanda Sarquis; Passos-Bueno, Maria Rita Santos; Zechi-Ceide, Roseli Maria

    2012-07-01

    We describe a girl with a phenotype characterized by frontonasal dysplasia, callosal agenesis, basal encephalocele, and eye anomalies who presents a 46,XX,r(21) karyotype. Array-comparative genomic hybridization using the Afflymetrix 100K DNA oligoarray set showed an interstitial deletion 21q22.3 of approximately 219 kb. Conventional karyotype of both parents was normal, and it was not possible to perform the molecular studies. In this report we raise the hypothesis that the deleted genes located at 21q22.3 could account to the phenotype.

  4. A new template to study callosal growth shows specific growth in anterior and posterior regions of the corpus callosum in early childhood.

    PubMed

    Ansado, Jennyfer; Collins, Louis; Fonov, Vladimir; Garon, Mathieu; Alexandrov, Lubomir; Karama, Sherif; Evans, Alan; Beauchamp, Miriam H

    2015-07-01

    Most of the studies conducted on the development of the corpus callosum (CC) have been limited to a relatively simple assessment of callosal area, providing an estimation of the size of the CC in two dimensions rather than its actual measurement. The goal of this study was to revisit callosal development in childhood and adolescence by using a three-dimensional (3D) magnetic resonance imaging template of the CC that considers the horizontal width of the CC and compares this with the two-dimensional (2D) callosal area. We mapped callosal growth in a large sample of youths followed longitudinally (N = 370 at T1; N = 304 at T2; and N = 246 at T3). Both techniques were based on a five-section subdivision of the CC. The results obtained with the 3D method revealed that the rate of CC growth over a 4-year period in the rostrum, the genu, the anterior body and the splenium was significantly higher in the youngest age group (< 7 years) than in older groups, indicating an intense period of development in early childhood for the anterior and posterior parts of the CC. Similar results were obtained when 2D callosal area was used for the anterior and posterior parts of the CC. However, divergent results were found in the mid-body and the caudal body of the CC. As shown by differences between 2D estimations and actual 3D measurements of callosal growth, our study highlights the importance of considering the horizontal width in measuring developmental changes in the CC. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  5. Endosidin 7 Specifically Arrests Late Cytokinesis and Inhibits Callose Biosynthesis, Revealing Distinct Trafficking Events during Cell Plate Maturation1[W][OPEN

    PubMed Central

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

    2014-01-01

    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. PMID:24858949

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

    PubMed

    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 space it serves.

  7. 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

  8. 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. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  9. Prostaglandin E2 induces spontaneous rhythmic activity in mouse urinary bladder independently of efferent nerves

    PubMed Central

    Kobayter, S; Young, JS; Brain, KL

    2012-01-01

    BACKGROUND AND PURPOSE The acute effects of PGE2 on bladder smooth muscle and nerves were examined to determine the origin of PGE2-induced spontaneous rhythmic contractions. EXPERIMENTAL APPROACH Contraction studies, confocal Ca2+ imaging and electrophysiological recordings in strips of mouse urinary bladder were used to differentiate the effects of PGE2 on bladder smooth muscle and efferent nerves. KEY RESULTS PGE2 (50 µM) increased the tone and caused phasic contractions of detrusor smooth muscle strips. Confocal Ca2+ imaging showed that PGE2 increased the frequency of whole-cell Ca2+ transients (WCTs) (72 ± 5%) and intracellular recordings showed it increased the frequency of spontaneous depolarizations, from 0.31·s−1 to 0.90·s−1. Non-selective inhibition of EP receptors using SC-51322 and AH-6809 (10 µM), or the L-type Ca2+ channel blocker nifedipine (1 µM), prevented these phasic contractions and WCTs, and reduced the tone (by 45 ± 7% and 59 ± 6%, respectively). Blocking P2X1 receptors with NF449 (10 µM) caused a small but significant reduction in the frequency of PGE2-induced phasic contractions (24 ± 9%) and WCTs (28 ± 17%) but had no significant effect on spontaneous depolarizations or tone. Inhibiting muscarinic receptors with cyclopentolate (1 µM) had no significant effect on these measures. Spontaneous WCTs became synchronous in PGE2, implying enhanced functional coupling between neighbouring cells. However, the electrical input resistance was unchanged. CONCLUSIONS AND IMPLICATIONS It was concluded that depolarization alone is sufficient to explain a functional increase in intercellular coupling and the ability of PGE2 to increase detrusor spontaneous rhythmic activity does not require parasympathetic nerves. PMID:21671904

  10. 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

  11. GPER1 in sand rat epididymis: Effects of seasonal variations, castration and efferent ducts ligation.

    PubMed

    Menad, Rafik; Fernini, Meriem; Smaï, Souaâd; Bonnet, Xavier; Gernigon-Spychalowicz, Thérèse; Moudilou, Elara; Khammar, Farida; Exbrayat, Jean-Marie

    2017-08-01

    Estrogen plays a crucial role in regulating epididymal function and development. Estrogen signaling is mediated via two main receptors essentially involved in the genomic regulating pathway: ERα and ERβ. Recent studies revealed the contribution of a novel estrogen receptor involved in the non-genomic pathway: GPER1. This receptor belongs to the family of seven-transmembrane G-protein-coupled receptors and it triggers rapid cellular responses. Immuno-histochemical studies and Western Blot analyses were performed to investigate the GPER1 expression in the caput and cauda epididymis of free-ranging fat sand rats (Psammomys obesus) captured during the breeding and resting seasons. We also investigated the effect of castration (C), castration followed by testosterone treatment (C+T), and ligation of the efferent ducts (L). During the breeding season, a marked positive GPER1 immunoreactivity was detected in the cytoplasm of principal cells and basal cells; this signal persisted during the resting season, attenuated however, meanwhile the clear cells were not immuno-reactive. In C animals, the immuno-histochemical staining underwent nuclear translocation. In C+T animals, this response became nuclear and cytoplasmic. In the L group, the expression of the GPER1 was mainly located in the cytoplasm of principal cells and in the nuclei of basal cells; the sperm was also immune-positive in the cauda epididymis. Western blot analysis showed that GPER1 has a molecular weight of 55kDa in the caput and cauda epididymis during the breeding season, and it persisted during the resting season in the caput epididymis with a decrease in the cauda epididymis. These results suggest that GPER1 mediate a specific cellular estrogen signaling with marked differences between the breeding and resting seasons. Experimental groups suggest that testosterone is involved in the regulation of the expression of GPER1, in addition to other estrogen signalization pathways. Copyright © 2017 Elsevier B

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

    PubMed

    Muller, Matthew D; Gao, Zhaohui; McQuillan, Patrick M; Leuenberger, Urs A; Sinoway, Lawrence I

    2014-07-15

    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. Copyright © 2014 the American Physiological Society.

  13. Changes in cochlear mechanics during vocalization: evidence for a phasic medial efferent effect.

    PubMed

    Goldberg, R L; Henson, O W

    1998-08-01

    The mustached bat, Pteronotus p. parnellii, has a finely tuned cochlea that rings at its resonant frequency in response to an acoustic tone pip. The decay time (DT) and frequency of these damped oscillations can be measured from the cochlear microphonic potential (CM) to study changes in cochlear mechanics. In this report, we describe phasic changes that occur in synchrony with communication sound vocalizations of the bat. Three animals with chronically implanted electrodes were studied. During the experiments, 1-2 ms tone pips were emitted from a speaker every 200 ms. This triggered a computer analysis of the resulting CM to determine the DT and cochlear resonance frequency (CRF) of the ringing. The time relative to vocalizations was determined by monitoring the output of a microphone placed near a bat's mouth. Similar results were obtained from all three bats tested. In a representative case, the average DT was 2.33 +/- 0.25 ms while the bat was quiet, but it decreased by 46% to 1.26 +/- 0.75 during vocalizations, which indicates a greater damping of the cochlear partition. Sometimes, DT started decreasing immediately before the bat vocalized. After the end of a vocalization, the return to baseline values varied from rapid (milliseconds) to gradual (1-2 seconds). The CRF also changed from baseline values during vocalization, although the amount and direction of change were not predictable. When gentamicin was administered to block the action of medial olivocochlear (MOC) efferents, DT reduction was still evident during vocalization but less pronounced. We conclude that phasic changes in damping occur in synchrony with vocalization, and that the MOC system plays a role in causing suppression. Since suppression can begin prior to vocalization, this may be a synkinetic effect, mediated by neural outflow to the ear in synchrony with neural outflow to the middle ear muscles and the muscles used for vocalization.

  14. 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.'

  15. Concurrent fast and slow synchronized efferent phrenic activities in time and frequency domain.

    PubMed

    Schmid, K; Böhmer, G; Weichel, T

    1990-09-24

    In urethane-anesthetized or decerebrated vagotomized rabbits efferent multifiber activity of the phrenic nerve was investigated for synchronized activities both in time and frequency domains. When respiratory drive was steadily increased by either an elevation of end-tidal CO2 concentration or i.v. administration of 4-aminopyridine, medium-frequency oscillations (MFO) first increased, then decreased and finally became absent. The power of high-frequency oscillations (HFO) steadily rose with increasing respiratory drive. In contrast to HFO which revealed a unimodal spectral peak of mostly small bandwidth, the MFO spectrum in most cases consisted of a broad complex. This complex in some cases was composed of two distinct peaks, i.e. MFO were heterogenous. The low- and high-frequency fractions of the MFO complex were related predominantly to the first and last third of inspiration, respectively. Examination of the on-going multifiber activity of the phrenic nerve with an expanded time scale revealed that lower frequency MFO probably result from synchronized ramp-like wave activity during early and mid-inspiration. The duration of the observed ramps well matched the corresponding MFO frequency. We suggest that these ramps might result from propagated synchronized waves of high-threshold phrenic motoneurons. During the last part of inspiration, however, MFO, like HFO, resulted from burst-like synchronized discharge of phenic motoneurons. Thus HFO are superimposed on ramp-like and burst-like activity of the MFO. It is assumed that the decline of MFO at high respiratory drive may be due to the increasing strength of HFO bursts which interrupt ramp activity in the MFO range and thus let MFO appear 'invisible' to the recording electrode. Both MFO and HFO were visually detectable in postinspiration.

  16. Central efferent pathways mediating skin cooling-evoked sympathetic thermogenesis in brown adipose tissue

    PubMed Central

    Nakamura, Kazuhiro; Morrison, Shaun F.

    2008-01-01

    Control of thermoregulatory effectors by the autonomic nervous system is a critical component of rapid cold-defense responses, which are triggered by thermal information from the skin. However, the central autonomic mechanism driving thermoregulatory effector responses to skin thermal signals remains to be determined. Here, we examined the involvement of several autonomic brain regions in sympathetic thermogenic responses in brown adipose tissue (BAT) to skin cooling in urethane-chloralose-anesthetized rats by monitoring thermogenic (BAT sympathetic nerve activity (SNA) and BAT temperature), metabolic (expired CO2), and cardiovascular (arterial pressure and heart rate) parameters. Acute skin cooling, which did not reduce either rectal (core) or brain temperature, evoked increases in BAT SNA, BAT temperature, expired CO2, and heart rate. Skin cooling-evoked thermogenic, metabolic, and heart rate responses were inhibited by bilateral microinjections of bicuculline (GABAA receptor antagonist) into the preoptic area (POA), by bilateral microinjections of muscimol (GABAA receptor agonist) into the dorsomedial hypothalamic nucleus (DMH), or by microinjection of muscimol, glycine, 8-OH-DPAT (5-HT1A receptor agonist), or kynurenate (non-selective antagonist for ionotropic excitatory amino acid receptors) into the rostral raphe pallidus nucleus (rRPa), but not by bilateral muscimol injections into the lateral/dorsolateral part or ventrolateral part of the caudal periaqueductal gray. These results implicate the POA, DMH, and rRPa in the central efferent pathways for thermogenic, metabolic, and cardiac responses to skin cooling, and suggest that these pathways can be modulated by serotonergic inputs to the medullary raphe. PMID:16931649

  17. Efferent projections of NPY expressing neurons of the dorsomedial hypothalamus in chronic hyperphagic models

    PubMed Central

    Lee, Shin J.; Kirigiti, Melissa; Lindsley, Sarah R; Loche, Alberto; Madden, Christopher J.; Morrison, Shaun F.; Smith, M Susan; Grove, Kevin L.

    2013-01-01

    The dorsomedial hypothalamus (DMH) has long been implicated in feeding behavior and thermogenesis. The DMH contains orexigenic neuropeptide Y (NPY) neurons, but the role of these neurons in the control of energy homeostasis is not well understood. NPY expression in the DMH is low under normal conditions in adult rodents, but is significantly increased during chronic hyperphagic conditions such as lactation and diet-induced obesity (DIO). To better understand the role of DMH-NPY neurons, we characterized the efferent projections of DMH-NPY neurons using the anterograde tracer biotinylated dextran amine (BDA) in lactating rats and DIO mice. In both models, BDA and NPY co-labeled fibers were mainly limited to the hypothalamus including the paraventricular nucleus of the hypothalamus (PVH), lateral hypothalamus/perifornical area (LH/PFA), and anteroventral periventricular nucleus (AVPV). Specifically in lactating rats, BDA and NPY co-labeled axonal swellings were in close apposition to CART expressing neurons in the PVH and AVPV. Although the DMH neurons project to the rostral raphe pallidus (rRPa) these projections did not contain NPY immunoreactivity in either the lactating rat or DIO mouse. Instead, the majority of BDA-labeled fibers in the rRPa were orexin positive. Furthermore, DMH-NPY projections were not observed within the nucleus of the solitary tract (NTS), another brainstem site critical for the regulation of sympathetic outflow. The present data suggest that NPY expression in the DMH during chronic hyperphagic conditions plays important roles in feeding behavior and thermogenesis by modulating neuronal functions within the hypothalamus, but not in the brainstem. PMID:23172177

  18. The Effects of Age, Memory Performance, and Callosal Integrity on the Neural Correlates of Successful Associative Encoding

    PubMed Central

    Wang, Tracy H.; Minton, Brian; Muftuler, L. Tugan; Rugg, Michael D.

    2011-01-01

    This functional magnetic resonance imaging study investigated the relationship between the neural correlates of associative memory encoding, callosal integrity, and memory performance in older adults. Thirty-six older and 18 young subjects were scanned while making relational judgments on word pairs. Neural correlates of successful encoding (subsequent memory effects) were identified by contrasting the activity elicited by study pairs that were correctly identified as having been studied together with the activity elicited by pairs wrongly judged to have come from different study trials. Subsequent memory effects common to the 2 age groups were identified in several regions, including left inferior frontal gyrus and bilateral hippocampus. Negative effects (greater activity for forgotten than for remembered items) in default network regions in young subjects were reversed in the older group, and the amount of reversal correlated negatively with memory performance. Additionally, older subjects' subsequent memory effects in right frontal cortex correlated positively with anterior callosal integrity and negatively with memory performance. It is suggested that recruitment of right frontal cortex during verbal memory encoding may reflect the engagement of processes that compensate only partially for age-related neural degradation. PMID:21282317

  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.

  20. Biosynthesis of callose and cellulose by detergent extracts of tobacco cell membranes and quantification of the polymers synthesized in vitro.

    PubMed

    Cifuentes, Carolina; Bulone, Vincent; Emons, Anne Mie C

    2010-02-01

    The conditions that favor the in vitro synthesis of cellulose from tobacco BY-2 cell extracts were determined. The procedure leading to the highest yield of cellulose consisted of incubating digitonin extracts of membranes from 11-day-old tobacco BY-2 cells in the presence of 1 mM UDP-glucose, 8 mM Ca(2+) and 8 mM Mg(2+). Under these conditions, up to nearly 40% of the polysaccharides synthesized in vitro corresponded to cellulose, the other polymer synthesized being callose. Transmission electron microscopy analysis revealed the occurrence of two types of structures in the synthetic reactions. The first type consisted of small aggregates with a diameter between 3 and 5 nm that associated to form fibrillar strings of a maximum length of 400 nm. These structures were sensitive to the acetic/nitric acid treatment of Updegraff and corresponded to callose. The second type of structures was resistant to the Updegraff reagent and corresponded to straight cellulose microfibrils of 2-3 nm in diameter and 200 nm to up to 5 microm in length. In vitro reactions performed on electron microscopy grids indicated that the minimal rate of microfibril elongation in vitro is 120 nm/min. Measurements of retardance by liquid crystal polarization microscopy as a function of time showed that small groups of microfibrils increased in retardance by up to 0.047 nm/min per pixel, confirming the formation of organized structures.

  1. 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.

  2. 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.

  3. 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.

  4. Role of the efferent medial olivocochlear system in contralateral masking and binaural interactions: an electrophysiological study in guinea pigs.

    PubMed

    Aran, J M; Pajor, A M; de Sauvage, R C; Erre, J P

    2000-01-01

    Contralateral broadband noise (BBN) elevates ipsilateral auditory thresholds (central masking) and reduces the amplitude of ipsilateral brainstem auditory evoked potentials (BAEPs). Binaural interactions are complex psychophysical phenomena, but binaural interaction components are easily extracted from BAEPs to monaural versus binaural click stimulation. However, contralateral, or binaural, acoustical stimulation is known to activate simultaneously the crossed and uncrossed medial olivocochlear (MOC) efferent systems and decrease activity in both cochleas. Particularly, contralateral BBN stimulation suppresses in part ipsilateral peripheral activity. What is the role of such contralaterally induced peripheral suppression in the overall changes in central BAEPs observed during contralateral masking or binaural stimulation? Compound action potentials (CAPs) of the auditory nerve and BAEPs were recorded simultaneously in awake guinea pigs from electrodes chronically implanted on the round window of the cochlea and the surface of the brain. Peripheral and central measures of contralateral masking and binaural interactions were obtained from responses to monaural or binaural clicks, with or without contralateral BBN, recorded before, during, and after the reversible blockade of the MOC function following a single intramuscular injection of gentamicin. Contralateral BBN effectively reduced the amplitudes of CAP and of all BAEP peaks. CAP to ipsilateral click did not, however, change significantly from monaural to binaural click stimulation; still, normal binaural interaction components developed in the BAEPs. When the medial efferent function was blocked by gentamicin, the normal contralateral BBN suppression of CAP and of the earliest BAEP peak was lost; however, the later BAEP peaks were suppressed by contralateral BBN as before gentamicin, and the central binaural interaction components were unchanged. In these experimental conditions, the MOC efferent system seems to

  5. 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.

  6. The physiologic effects of ileal reservoirs and efferent conduits complementing ileoanal anastomosis: an experimental study in dogs.

    PubMed

    Rosemurgy, A S; Schraut, W H; Block, G E

    1983-10-01

    S-shaped ileal reservoirs (SSRs) and double-barreled ileal reservoirs (DBRs) of equal size were placed 6 or 2 cm from the anus and evaluated over 1 year for their ability to improve the functional incontinence noted after an ileoanal anastomosis (IAA). Compared to straight IAA, both reservoirs prolonged intestinal transit (235 minutes versus 135 minutes, P less than 0.001) and alleviated frequency without causing nutritional abnormalities. The capacity of the reservoirs was greater than that of a comparable length of distal ileum in dogs (n = 6) with straight IAA (304 +/- 16 ml versus 102 +/- 2 ml, P less than 0.001). The SSRs (n = 9), in contrast to the DBRs (n = 10), developed excessive volume capacity (360 +/- 30 ml versus 254 +/- 104 ml, P less than 0.01) and obstructive complications. Reservoirs with 6 cm efferent conduits (n = 13), in contrast to those with a 2 cm efferent conduit (n = 6), underwent marked dilatation (334 +/- 24 ml versus 238 +/- 13 ml, P less than 0.005). Electromyography and manometry revealed the DBRs to be more contractile than the SSRs but less than ileum proximal to the anus in dogs with a straight IAA. Ileal reservoirs improve results after IAA. Reservoirs should be complaint and yet contractile (e.g., DBR) so as to discourage excessive dilatation, which is the harbinger of obstruction. Ileal conduits facilitate reservoir placement, but if longer than 2 cm they excessively impeded reservoir emptying, predisposing to excessive reservoir dilatation and obstruction. A DBR with a 2 cm efferent conduit results in continence without obstructive problems.

  7. Axonal transport of neurotrophins by visceral afferent and efferent neurons of the vagus nerve of the rat.

    PubMed

    Helke, C J; Adryan, K M; Fedorowicz, J; Zhuo, H; Park, J S; Curtis, R; Radley, H E; Distefano, P S

    1998-03-30

    The receptor-mediated axonal transport of [125I]-labeled neurotrophins by afferent and efferent neurons of the vagus nerve was determined to predict the responsiveness of these neurons to neurotrophins in vivo. [125I]-labeled neurotrophins were administered to the proximal stump of the transected cervical vagus nerve of adult rats. Vagal afferent neurons retrogradely transported [125I]neurotrophin-3 (NT-3), [125I]nerve growth factor (NGF), and [125I]neurotrophin-4 (NT-4) to perikarya in the ipsilateral nodose ganglion, and transganglionically transported [125I]NT-3, [125I]NGF, and [125I]NT-4 to the central terminal field, the nucleus tractus solitarius (NTS). Vagal afferent neurons showed minimal accumulation of [125I]brain-derived neurotrophic factor (BDNF). In contrast, efferent (parasympathetic and motor) neurons located in the dorsal motor nucleus of the vagus and nucleus ambiguus retrogradely transported [125I]BDNF, [125I]NT-3, and [125I]NT-4, but not [125I]NGF. The receptor specificity of neurotrophin transport was examined by applying [125I]-labeled neurotrophins with an excess of unlabeled neurotrophins. The retrograde transport of [125I]NT-3 to the nodose ganglion was reduced by NT-3 and by NGF, and the transport of [125I]NGF was reduced only by NGF, whereas the transport of [125I]NT-4 was significantly reduced by each of the neurotrophins. The competition profiles for the transport of NT-3 and NGF are consistent with the presence of TrkA and TrkC and the absence of TrkB in the nodose ganglion, whereas the profile for NT-4 suggests a p75 receptor-mediated transport mechanism. The transport profiles of neurotrophins by efferent vagal neurons in the dorsal motor nucleus of the vagus and nucleus ambiguus are consistent with the presence of TrkB and TrkC, but not TrkA, in these nuclei. These observations describe the unique receptor-mediated axonal transport of neurotrophins in adult vagal afferent and efferent neurons and thus serve as a template to discern

  8. Association between preoperative pain intensity of MTP joint callosities of the lesser toes and fore-mid-hindfoot deformities in rheumatoid arthritis cases.

    PubMed

    Hirao, Makoto; Ebina, Kosuke; Shi, Kenrin; Tomita, Tetsuya; Noguchi, Takaaki; Tsuboi, Hideki; Hashimoto, Jun; Yoshikawa, Hideki

    2017-01-01

    To determine whether preoperative pain intensity in callosities of the lesser toe metatarsopharangeal (MTP) joint was associated with the grade of fore-mid-hindfoot deformities, because rheumatoid arthritis (RA) foot deformity includes the whole part of foot, and curiously differences between cases in the pain intensity of MTP joint callosities are often observed. We evaluated 24 feet that had undergone forefoot surgery [August, 2014 - December, 2015] for painful lesser toe MTP joint deformity (callosities) in RA cases. A preoperative self-administered foot evaluation questionnaire (SAFE-Q) and pressure distribution information for foot function were also investigated. X-rays of the whole lower extremities and foot at weight-bearing were used to check fore-mid-hindfoot deformities. Group M (mild) [n = 9] included patients with the pain visual analog scale (VAS) less than 40 mm, while group S (severe) [n = 15] included patients whose VAS was over 40 mm. Group M showed stronger hindfoot valgus and pronated (abducted) deformity, and group M showed higher pressure on the first MTP joint compared with group S. These observations reconfirm that hindfoot valgus deformity and/or pronated (abducted) foot deformity affects the forefoot loading distribution, subsequently the pain of callosities in lesser toe MTP joints could be decreased.

  9. Differential accumulation of callose, arabinoxylan and cellulose in nonpenetrated versus penetrated papillae on leaves of barley infected with Blumeria graminis f. sp. hordei.

    PubMed

    Chowdhury, Jamil; Henderson, Marilyn; Schweizer, Patrick; Burton, Rachel A; Fincher, Geoffrey B; Little, Alan

    2014-11-01

    In plants, cell walls are one of the first lines of defence for protecting cells from successful invasion by fungal pathogens and are a major factor in basal host resistance. For the plant cell to block penetration attempts, it must adapt its cell wall to withstand the physical and chemical forces applied by the fungus. Papillae that have been effective in preventing penetration by pathogens are traditionally believed to contain callose as the main polysaccharide component. Here, we have re-examined the composition of papillae of barley (Hordeum vulgare) attacked by the powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh) using a range of antibodies and carbohydrate-binding modules that are targeted to cell wall polysaccharides. The data show that barley papillae induced during infection with Bgh contain, in addition to callose, significant concentrations of cellulose and arabinoxylan. Higher concentrations of callose, arabinoxylan and cellulose are found in effective papillae, compared with ineffective papillae. The papillae have a layered structure, with the inner core consisting of callose and arabinoxylan and the outer layer containing arabinoxylan and cellulose. The association of arabinoxylan and cellulose with penetration resistance suggests new targets for the improvement of papilla composition and enhanced disease resistance. © 2014 University of Adelaide. New Phytologist © 2014 New Phytologist Trust.

  10. Novel Bifunctional Nucleases, OmBBD and AtBBD1, Are Involved in Abscisic Acid-Mediated Callose Deposition in Arabidopsis1[W][OA

    PubMed Central

    You, Min Kyoung; Shin, Hyun Young; Kim, Young Jin; Ok, Sung Han; Cho, Sung Ki; Jeung, Ji Ung; Yoo, Sang Dong; Kim, Jeong Kook; Shin, Jeong Sheop

    2010-01-01

    Screening of the expressed sequence tag library of the wild rice species Oryza minuta revealed an unknown gene that was rapidly and strongly induced in response to attack by a rice fungal pathogen (Magnaporthe oryzae) and an insect (Nilaparvata lugens) and by wounding, abscisic acid (ABA), and methyl jasmonate treatments. Its recombinant protein was identified as a bifunctional nuclease with both RNase and DNase activities in vitro. This gene was designated OmBBD (for O. minuta bifunctional nuclease in basal defense response). Overexpression of OmBBD in an Arabidopsis (Arabidopsis thaliana) model system caused the constitutive expression of the PDF1.2, ABA1, and AtSAC1 genes, which are involved in priming ABA-mediated callose deposition. This activation of defense responses led to an increased resistance against Botrytis cinerea. atbbd1, the knockout mutant of the Arabidopsis ortholog AtBBD1, was susceptible to attack by B. cinerea and had deficient callose deposition. Overexpression of either OmBBD or AtBBD1 in atbbd1 plants complemented the susceptible phenotype of atbbd1 against B. cinerea as well as the deficiency of callose deposition. We suggest that OmBBD and AtBBD1 have a novel regulatory role in ABA-mediated callose deposition. PMID:20018603

  11. Cellular change and callose accumulation in zygotic embryos of Eleutherococcus senticosus caused by plasmolyzing pretreatment result in high frequency of single-cell-derived somatic embryogenesis.

    PubMed

    Ling You, Xiang; Seon Yi, Jae; Eui Choi, Yong

    2006-05-01

    Eleutherococcus senticosus zygotic embryos were pretreated with 1.0 M mannitol or sucrose for 3-24 h. This pretreatment resulted in a high frequency of somatic-embryo formation on hormone-free medium. All the somatic embryos developed directly and independently from single epidermal cells on the surface of zygotic embryos after plasmolyzing pretreatment. Scanning electron microscopic observation revealed that the epidermal cells of hypocotyls rapidly became irregular and showed a random orientation before somatic-embryo development commenced. At the same time, the epidermal cells in the untreated control remained regular. Callose concentration determined by fluorometric analysis increased sharply in E. senticosus zygotic embryos after plasmolyzing pretreatment but remained low in the untreated control. Aniline blue fluorescent staining of callose showed that the plasmolyzing pretreatment of zygotic embryos resulted in heavy accumulation of callose between the plasma membrane and cell walls. On the basis of these results, we suggest that plasmolyzing pretreatment of zygotic embryos induces the accumulation of callose, and the interruption of cell-to-cell communication imposed by this might stimulate the reprogramming of epidermal cells into embryogenically competent cells and finally induce somatic-embryo development from single cells.

  12. Cerebellar cortical efferent fibers of the paraflocculus of tree shrew (Tupaia glis).

    PubMed

    Haines, D E; Whitworth, R H

    1978-11-01

    Efferent projections from the paraflocculus of the tree shrew (Tupaia glis) were studied utilizing the Fink and Heimer ('67) method. Cerebellar corticonuclear fibers of both dorsal (Dpf) and ventral (Vpf) divisions of the paraflocculus terminate in the lateral cerebellar nucelus (NL) and in the posterior interposed nucleus (NIP). These fibers are ipsilateral, topographically organized and arranged into at least two zones. Following injury to either the Dpf or Vpf, degenerated axons are found in lateral and caudal regions of the NIP respectively. Consequently, these two portions of the paraflocculus have relatively exclusive terminal fields with overlap only at the periphery. Preterminal debris is seen in basically similar areas of the NL (caudolateral, caudal, ventral) after damage to either the Dpf or Vpf. This observation leads to the conclusion that the terminal fields for these areas of parafloccular cortex are largely coextensive in the NL. In addition to the topographical representation of the Dpf and Vpf in both the NL and NIP, there is evidence that these corticonuclear fibers are also organized into the general zonal pattern hypothesized by Voogd ('69). Persistent and numerous degenerated axons from both the Dpf and Vpf end in lateral and caudal NIP, respectively, corroborating the presence of a relatively wide zone C2 in both divisions of the paraflocculus. The Dpf and Vpf also project into the NL to a terminal field that appears to consist of two portions. One part located in caudal, ventral and/or caudoventral areas of the NL and a second at slightly more rostral and rostrolateral areas. The presence of a cortical region which is affiliated with two areas of the NL substantiates not only the existence of zone D in the paraflocculus, but gives experimental evidence that it may consist of two parts as previously suggested (Voogd, '69). From the Dpf many fibers enter the NL while few are seen in this nucleus after damage to the Vpf. This suggests that zone

  13. 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

  14. The Impact of Feet Callosities, Arm Posture, and Usage of Electrolyte Wipes on Body Composition by Bioelectrical Impedance Analysis in Morbidly Obese Adults.

    PubMed

    Roekenes, Jessica; Strømmen, Magnus; Kulseng, Bård; Martins, Catia

    2015-01-01

    This study evaluated the impact of feet callosities, arm posture, and use of electrolyte wipes on body composition measurements by bioelectrical impedance analysis (BIA) in morbidly obese adults. 36 morbidly obese patients (13 males, aged 28-70 years, BMI 41.6 ± 4.3 kg/m2) with moderate/severe feet callosities participated in this study. Body composition (percent body fat (%BF)) was measured while fasting using multi-frequency BIA (InBody 720®), before and after removal of callosities, with and without InBody® electrolyte wipes and custom-built auxiliary pads (to assess arm posture impact). Results from BIA were compared to air displacement plethysmography (ADP, BodPod®). Median %BF was significantly higher with auxiliary pads than without (50.1 (interquartile range 8.2) vs. 49.3 (interquartile range 9.1); p < 0.001), while no differences were found with callosity removal (49.3 (interquartile range 9.1) vs. 50.0 (interquartile range 7.9); NS) or use of wipes (49.6 (interquartile range 8.5) vs. 49.3 (interquartile range 9.1); NS). No differences in %BF were found between BIA and ADP (49.1 (IQR: 8.9) vs. 49.3 (IQR: 9.1); NS). Arm posture has a significant impact on %BF assessed by BIA, contrary to the presence of feet callosities and use of electrolyte wipes. Arm posture standardization during BIA for body composition assessment is, therefore, recommended. © 2015 S. Karger GmbH, Freiburg.

  15. Time-frequency analysis of visual evoked potentials for interhemispheric transfer time and proportion in callosal fibers of different diameters.

    PubMed

    Ulusoy, Ilkay; Halici, Ugur; Nalçaci, Erhan; Anaç, Ilker; Leblebicio Eroğlu, Kemal; Başar-Eroğlu, Canan

    2004-04-01

    This study is an extension of the experimental research of Nalçaci et al., who presented 16 subjects with a reversal of checkerboard pattern as stimuli in the right visual field or left visual field and recorded EEG at O1, O2, P3, and P4. They applied the chosen bandpass filters (4-8, 8-15, 15-20, 20-32 Hz) to the VEPs of subjects and obtained four different components for each VEP. The first aim of this study is to improve the previous report using some methods in time-frequency domain to estimate interhemispheric delays and amplitudes in a time window. Using the improved estimates of interhemispheric delays, the second aim is to estimate the proportion of callosal fibers of different diameters that are activated by visual stimuli by comparing amplitudes of VEPs in different frequency bands. If the relation between frequency components of VEP and delays for callosal fibers of different dimension were reliable, it would give us an opportunity to deal with amplitude of bandpass-filtered VEPs in order to see approximately the proportion of these fibers activated by a certain stimulus. By using frequency-dependent shifts in time and maximizing the cross correlation of direct VEP (DVEP-VEP obtained from contralateral hemisphere)-indirect VEP (IVEP-VEP obtained from ipsilateral hemisphere) pairs in the time-frequency domain, we examined the delay not only at P100 and N160 peaks but along a meaningful time interval as well. Furthermore, by shifting back the IVEP according to the delay estimated at each time window, both the amplitudes and energies of the synchronized DVEP-IVEP pairs were compared at the chosen frequency bands. The percentages of IVEPs at each band was then examined further in conjunction with the distribution of axon diameters in the posterior pole of the CC, questioning the relation between the distributions of the axon diameters and activations at each band. We established an energy definition to express the activation in the fibers. When the energy

  16. [Readjustment of the efferent activity of the scratching generator in response to stimulation of muscle afferents of the hindlimb of the decerebrate immobilized cat].

    PubMed

    Shimanskiĭ, Iu P; Baev, K V

    1987-01-01

    Rebuildings of the scratching generator activity caused by phasic electrical stimulation of ipsilateral hindlimb muscle nerves during different hindlimb positions were studied in decerebrated immobilized cats. Strong dependence of these rebuildings on the stimulation phase was observed. The character of the "scratch" cycle duration rebuilding was formed by the scratching generator tendency to bring efferent activity into such correlation with the stimulus that the stimulation moment coincided with the moment of efferent activity phase triggering. Phasic altering of the efferent activity intensity rebuilding was observed against a background of "aiming" and "scratching" activity correlation shift in the direction of strengthening activation of muscles innervated by the stimulated nerve. This rebuilding was intensified when the hindlimb deflects from the aimed position in the direction of corresponding muscles stretching. Physiological sense of "rebuilding absence phases" is discussed. It is postulated that absence of the duration and intensity changes can be achieved simultaneously only with definite correlation between phase and intensity of the afferent impulsation burst.

  17. Interaction between gustatory depolarizing receptor potential and efferent-induced slow depolarizing synaptic potential in frog taste cell.

    PubMed

    Sato, Toshihide; Nishishita, Kazuhisa; Okada, Yukio; Toda, Kazuo

    2009-03-01

    Electrical stimulation of parasympathetic nerve (PSN) efferent fibers in the glossopharyngeal nerve induced a slow depolarizing synaptic potential (DSP) in frog taste cells under hypoxia. The objective of this study is to examine the interaction between a gustatory depolarizing receptor potential (GDRP) and a slow DSP. The amplitude of slow DSP added to a tastant-induced GDRP of 10 mV was suppressed to 60% of control slow DSPs for NaCl and acetic acid stimulations, but to 20-30% for quinine-HCl (Q-HCl) and sucrose stimulations. On the other hand, when a GDRP was induced during a prolonged slow DSP, the amplitude of GDRPs induced by 1 M NaCl and 1 M sucrose was suppressed to 50% of controls, but that by 1 mM acetic acid and 10 mM Q-HCl unchanged. It is concluded that the interaction between GDRPs and efferent-induced slow DSPs in frog taste cells under hypoxia derives from the crosstalk between a gustatory receptor current across the receptive membrane and a slow depolarizing synaptic current across the proximal subsynaptic membrane of taste cells.

  18. Reinnervation of renal afferent and efferent nerves at 5.5 and 11 months after catheter-based radiofrequency renal denervation in sheep.

    PubMed

    Booth, Lindsea C; Nishi, Erika E; Yao, Song T; Ramchandra, Rohit; Lambert, Gavin W; Schlaich, Markus P; May, Clive N

    2015-02-01

    Previous studies indicate that catheter-based renal denervation reduces blood pressure and renal norepinephrine spillover in human resistant hypertension. The effects of this procedure on afferent sensory and efferent sympathetic renal nerves, and the subsequent degree of reinnervation, have not been investigated. We therefore examined the level of functional and anatomic reinnervation at 5.5 and 11 months after renal denervation using the Symplicity Flex catheter. In normotensive anesthetized sheep (n=6), electric stimulation of intact renal nerves increased arterial pressure from 99±3 to 107±3 mm Hg (afferent response) and reduced renal blood flow from 198±16 to 85±20 mL/min (efferent response). In a further group (n=6), immediately after denervation, renal sympathetic nerve activity was absent and the responses to electric stimulation were abolished. At 11 months after denervation (n=5), renal sympathetic nerve activity and the responses to electric stimulation were at normal levels. Immunohistochemical staining for renal efferent (tyrosine hydroxylase) and renal afferent nerves (calcitonin gene-related peptide), as well as renal norepinephrine levels, was normal 11 months after denervation. Findings at 5.5 months after denervation were similar (n=5). In summary, catheter-based renal denervation effectively ablated the renal afferent and efferent nerves in normotensive sheep. By 11 months after denervation the functional afferent and efferent responses to electric stimulation were normal. Reinnervation at 11 months after denervation was supported by normal anatomic distribution of afferent and efferent renal nerves. In view of this evidence, the mechanisms underlying the prolonged hypotensive effect of catheter-based renal denervation in human resistant hypertension need to be reassessed.

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

    PubMed Central

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

    2014-01-01

    Summary 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

  20. 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.

  1. Interhemispheric functional connectivity in anorexia and bulimia nervosa.

    PubMed

    Canna, Antonietta; Prinster, Anna; Monteleone, Alessio Maria; Cantone, Elena; Monteleone, Palmiero; Volpe, Umberto; Maj, Mario; Di Salle, Francesco; Esposito, Fabrizio

    2017-05-01

    The functional interplay between hemispheres is fundamental for behavioral, cognitive, and emotional control. Anorexia nervosa (AN) and bulimia nervosa (BN) have been largely studied with brain magnetic resonance imaging (MRI) in relation to the functional mechanisms of high-level processing, but not in terms of possible inter-hemispheric functional connectivity anomalies. Using resting-state functional MRI (fMRI), voxel-mirrored homotopic connectivity (VMHC) and regional inter-hemispheric spectral coherence (IHSC) were studied in 15 AN and 13 BN patients and 16 healthy controls (HC). Using T1-weighted and diffusion tensor imaging MRI scans, regional VMHC values were correlated with the left-right asymmetry of corresponding homotopic gray matter volumes and with the white matter callosal fractional anisotropy (FA). Compared to HC, AN patients exhibited reduced VMHC in cerebellum, insula, and precuneus, while BN patients showed reduced VMHC in dorso-lateral prefrontal and orbito-frontal cortices. The regional IHSC analysis highlighted that the inter-hemispheric functional connectivity was higher in the 'Slow-5' band in all regions except the insula. No group differences in left-right structural asymmetries and in VMHC vs. callosal FA correlations were significant in the comparisons between cohorts. These anomalies, not explained by structural changes, indicate that AN and BN, at least in their acute phase, are associated with a loss of inter-hemispheric connectivity in regions implicated in self-referential, cognitive control and reward processing. These findings may thus gather novel functional markers to explore aberrant features of these eating disorders. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  2. Medial-olivocochlear-efferent inhibition of the first peak of auditory-nerve responses: Evidence for a new motion within the cochlea

    NASA Astrophysics Data System (ADS)

    Guinan, John J.; Lin, Tai; Cheng, Holden

    2005-10-01

    Despite the insights obtained from click responses, the effects of medial-olivocochlear (MOC) efferents on click responses from single-auditory-nerve (AN) fibers have not been reported. We recorded responses of cat single AN fibers to randomized click level series with and without electrical stimulation of MOC efferents. MOC stimulation inhibited (1) the whole response at low sound levels, (2) the decaying part of the response at all sound levels, and (3) the first peak of the response at moderate to high sound levels. The first two effects were expected from previous reports using tones and are consistent with a MOC-induced reduction of cochlear amplification. The inhibition of the AN first peak, which was strongest in the apex and middle of the cochlea, was unexpected because the first peak of the classic basilar-membrane (BM) traveling wave receives little or no amplification. In the cochlear base, the click data were ambiguous, but tone data showed particularly short group delays in the tail-frequency region that is strongly inhibited by MOC efferents. Overall, the data support the hypothesis that there is a motion that bends inner-hair-cell stereocilia and can be inhibited by MOC efferents, a motion that is present through most, or all, of the cochlea and for which there is no counterpart in the classic BM traveling wave.

  3. Dual efferent projections of the trigeminal principal sensory nucleus to the thalamic ventroposteromedial nucleus in the squirrel monkey.

    PubMed

    Ganchrow, D; Mehler, W R

    1986-07-24

    Anterograde degeneration methods demonstrated two efferent components from the trigeminal principal sensory nucleus (PrV) to the thalamic ventroposteromedial nucleus (VPM) in the squirrel monkey: fibers from the dorsal PrV coursed within the central tegmental tract and terminated in a dorsoventromedial strip of the ipsilateral VPM; fibers from the ventral PrV mainly decussated caudal to the interpeduncular nucleus and terminated in the contralateral VPM exclusive of the sector receiving the dorsal PrV component, contralaterally. Adjacent Nissl sections showed an apparent increase in glial profiles accompanying an intense somal staining among the deafferented neuronal population in the VPM, coextensive with those regions in the VPM exhibiting terminal field degeneration.

  4. Subfornical organ neurons with efferent projections to the hypothalamic paraventricular nucleus: an electrophysiological study in the rat.

    PubMed

    Tanaka, J; Kaba, H; Saito, H; Seto, K

    1985-10-28

    Seventeen neurons in the subfornical organ (SFO) were antidromically activated by electrical stimulation of the paraventricular nucleus (PVN) in the rat. The activity of all identified SFO neurons was excited by microiontophoretically (MIPh) applied angiotensin II (AII) and the effect of AII was blocked by MIPh-applied saralasin (Sar), an AII antagonist, but not by atropine (Atr), a muscarinic antagonist. In these identified SFO neurons, 9 were also excited and 8 were not affected by MIPh-applied acetylcholine (ACh) and the effect of ACh was attenuated by not only MIPh-applied Atr but also by Sar. These results suggest that there are specific AII- and both AII- and ACh-sensitive types of SFO neurons with efferent projections to the PVN.

  5. Delayed coronary reperfusion is ineffective at impeding the dynamic increase in cardiac efferent sympathetic nerve activity following myocardial ischemia.

    PubMed

    Hall, Timothy M; Gordon, Christina; Roy, Ranjan; Schwenke, Daryl O

    2016-05-01

    Acute myocardial infarction (MI) is associated with an adverse and sustained increase in cardiac sympathetic nerve activity (SNA), triggering potentially fatal ventricular arrhythmias. While myocardial reperfusion undoubtedly improves patient prognosis, it remains unknown whether reperfusion therapy also attenuates the dangerous increase in SNA. This study aimed to investigate the effect of time-dependent coronary reperfusion therapy on cardiac SNA following acute MI. Electrophysiological recordings of cardiac efferent SNA were performed in urethane-anaesthetized rats following ligation of the left anterior descending coronary artery (i.e., MI) for either 15 or 45 min, followed by 'early' or 'delayed' reperfusion, respectively. Another group of rats had permanent ischemia with no reperfusion. Forty-five minutes of ischemia induced a 55 % increase in efferent SNA. Subsequent 'delayed' reperfusion was ineffective at ameliorating further increases in SNA (maximal 153 % increase), so that MI-induced increases in SNA mirrored that observed in rats with permanent MI. Although SNA did not increase during 15 min of ischemia, it did significantly increase, albeit delayed, during the subsequent reperfusion period (max. 75 % increase). Importantly, however, this increase in SNA, which tended to be lower in the 'early'-reperfusion group, was matched with a lower incidence of arrhythmias and mortality rate, compared to the 'delayed'-reperfusion and permanent-MI groups. These results highlight that 'prompt' coronary reperfusion, before SNA becomes activated, may provide a crucial window of opportunity for improving outcome. Further research is essential to identify the mechanisms that underpin, not only sympathetic activation, but also importantly sympathetic deactivation as a potential therapeutic target for MI.

  6. Central command does not decrease cardiac parasympathetic efferent nerve activity during spontaneous fictive motor activity in decerebrate cats.

    PubMed

    Kadowaki, Akito; Matsukawa, Kanji; Wakasugi, Rie; Nakamoto, Tomoko; Liang, Nan

    2011-04-01

    To examine whether withdrawal of cardiac vagal efferent nerve activity (CVNA) predominantly controls the tachycardia at the start of exercise, the responses of CVNA and cardiac sympathetic efferent nerve activity (CSNA) were directly assessed during fictive motor activity that occurred spontaneously in unanesthetized, decerebrate cats. CSNA abruptly increased by 71 ± 12% at the onset of the motor activity, preceding the tachycardia response. The increase in CSNA lasted for 4-5 s and returned to the baseline, even though the motor activity was not ended. The increase of 6 ± 1 beats/min in heart rate appeared with the same time course of the increase in CSNA. In contrast, CVNA never decreased but increased throughout the motor activity, in parallel with a rise in mean arterial blood pressure (MAP). The peak increase in CVNA was 37 ± 9% at 5 s after the motor onset. The rise in MAP gradually developed to 21 ± 2 mmHg and was sustained throughout the spontaneous motor activity. Partial sinoaortic denervation (SAD) blunted the baroreflex sensitivity of the MAP-CSNA and MAP-CVNA relationship to 22-33% of the control. Although partial SAD blunted the initial increase in CSNA to 53% of the control, the increase in CSNA was sustained throughout the motor activity. In contrast, partial SAD almost abolished the increase in CVNA during the motor activity, despite the augmented elevation of 31 ± 1 mmHg in MAP. Because afferent inputs from both muscle receptors and arterial baroreceptors were absent or greatly attenuated in the partial SAD condition, only central command was operating during spontaneous fictive motor activity in decerebrate cats. Therefore, it is likely that central command causes activation of cardiac sympathetic outflow but does not produce withdrawal of cardiac parasympathetic outflow during spontaneous motor activity.

  7. 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.

  8. Absence of Cu-Zn superoxide dismutase BCSOD1 reduces Botrytis cinerea virulence in Arabidopsis and tomato plants, revealing interplay among reactive oxygen species, callose and signalling pathways.

    PubMed

    López-Cruz, Jaime; Óscar, Crespo-Salvador; Emma, Fernández-Crespo; Pilar, García-Agustín; Carmen, González-Bosch

    2017-01-01

    Plants activate responses against pathogens, including the oxidative burst. Necrotrophic pathogens can produce reactive oxygen species (ROS) that benefit the colonization process. Previously, we have demonstrated that tomato plants challenged with Botrytis cinerea accumulate ROS and callose, together with the induction of genes involved in defence, signalling and oxidative metabolism. Here, we studied the infection phenotype of the Δbcsod1 strain in both tomato and Arabidopsis plants. This mutant lacks bcsod1, which encodes Cu-Zn superoxide dismutase (SOD). This enzyme catalyses the conversion of superoxide ion ( O2-) into hydrogen peroxide (H2 O2 ). ROS play a protective role and act as signals in plants. Δbcsod1 displayed reduced virulence compared with wild-type B05.10 in both species. Plants infected with Δbcsod1 accumulated less H2 O2 and more O2- than those infected with B05.10, which is associated with an increase in the defensive polymer callose. This supports a major role of fungal SOD in H2 O2 production during the plant-pathogen interaction. The early induction of the callose synthase gene PMR4 suggested that changes in ROS altered plant defensive responses at the transcriptional level. The metabolites and genes involved in signalling and in response to oxidative stress were differentially expressed on Δbcsod1 infection, supporting the notion that plants perceive changes in ROS balance and activate defence responses. A higher O2(-) /H2 O2 ratio seems to be beneficial for plant protection against this necrotroph. Our results highlight the relevance of callose and the oxylipin 12-oxo-phytodienoic acid (OPDA) in the response to changes in the oxidative environment, and clarify the mechanisms that underlie the responses to Botrytis in Arabidopsis and tomato plants. © 2016 BSPP and John Wiley & Sons Ltd.

  9. Ca2+ and Ca2+-activated K+ channels that support and modulate transmitter release at the olivocochlear efferent-inner hair cell synapse

    PubMed Central

    de San Martín, Javier Zorrilla; Pyott, Sonja; Ballestero, Jimena; Katz, Eleonora

    2010-01-01

    In the mammalian auditory system, the synapse between efferent olivocochlear (OC) neurons and sensory cochlear hair cells is cholinergic, fast and inhibitory. This efferent synapse is mediated by the nicotinic α9α10 receptor coupled to the activation of SK2 Ca2+-activated K+ channels that hyperpolarize the cell. So far, the ion channels that support and/or modulate neurotransmitter release from the OC terminals remain unknown. To identify these channels, we used an isolated mouse cochlear preparation and monitored transmitter release from the efferent synaptic terminals in inner hair cells (IHCs) voltage-clamped in the whole-cell recording configuration. Acetylcholine (ACh) release was evoked by electrically stimulating the efferent fibers that make axosomatic contacts with IHCs before the onset of hearing. Using the specific antagonists for P/Q-and N-type voltage-gated calcium channels (VGCCs), ω-agatoxin IVA and ω-conotoxin GVIA, respectively, we show that Ca2+ entering through both types of VGCCs support the release process at this synapse. Interestingly, we found that Ca2+ entering through the dihydropiridine-sensitive L-type VGCCs exerts a negative control on transmitter release. Moreover, using immunostaining techniques combined with electrophysiology and pharmacology, we show that BK Ca2+-activated K+ channels are transiently expressed at the OC efferent terminals contacting IHCs and that their activity modulates the release process at this synapse. The effects of dihydropiridines combined with iberiotoxin, a specific BK channel antagonist, strongly suggest that L-type VGCCs negatively regulate the release of ACh by fueling BK channels which are known to curtail the duration of the terminal action potential in several types of neurons. PMID:20826678

  10. Ca(2+) and Ca(2+)-activated K(+) channels that support and modulate transmitter release at the olivocochlear efferent-inner hair cell synapse.

    PubMed

    Zorrilla de San Martín, Javier; Pyott, Sonja; Ballestero, Jimena; Katz, Eleonora

    2010-09-08

    In the mammalian auditory system, the synapse between efferent olivocochlear (OC) neurons and sensory cochlear hair cells is cholinergic, fast, and inhibitory. This efferent synapse is mediated by the nicotinic alpha9alpha10 receptor coupled to the activation of SK2 Ca(2+)-activated K(+) channels that hyperpolarize the cell. So far, the ion channels that support and/or modulate neurotransmitter release from the OC terminals remain unknown. To identify these channels, we used an isolated mouse cochlear preparation and monitored transmitter release from the efferent synaptic terminals in inner hair cells (IHCs) voltage clamped in the whole-cell recording configuration. Acetylcholine (ACh) release was evoked by electrically stimulating the efferent fibers that make axosomatic contacts with IHCs before the onset of hearing. Using the specific antagonists for P/Q- and N-type voltage-gated calcium channels (VGCCs), omega-agatoxin IVA and omega-conotoxin GVIA, respectively, we show that Ca(2+) entering through both types of VGCCs support the release process at this synapse. Interestingly, we found that Ca(2+) entering through the dihydropiridine-sensitive L-type VGCCs exerts a negative control on transmitter release. Moreover, using immunostaining techniques combined with electrophysiology and pharmacology, we show that BK Ca(2+)-activated K(+) channels are transiently expressed at the OC efferent terminals contacting IHCs and that their activity modulates the release process at this synapse. The effects of dihydropiridines combined with iberiotoxin, a specific BK channel antagonist, strongly suggest that L-type VGCCs negatively regulate the release of ACh by fueling BK channels that are known to curtail the duration of the terminal action potential in several types of neurons.

  11. Segmental Expression of the Bradykinin Type 2 Receptor in Rat Efferent Ducts and Epididymis and Its Role in the Regulation of Aquaporin 91

    PubMed Central

    Belleannée, C.; Silva, N. Da; Shum, W.W.C.; Marsolais, M.; Laprade, R.; Brown, D.; Breton, S.

    2008-01-01

    Water and solute transport in the efferent ducts and epididymis are important for the establishment of the appropriate luminal environment for sperm maturation and storage. Aquaporin 9 (AQP9) is the main water channel in the epididymis, but its regulation is still poorly understood. Components of the kinin-kallikrein system (KKS), leading to the production of bradykinin (BK), are highly expressed in the lumen of the male reproductive tract. We report here that the epididymal luminal fluid contains a significant amount of BK (2 nM). RT-PCR performed on epididymal epithelial cells isolated by laser capture microdissection (LCM) showed abundant BK type 2 receptor (Bdkrb2) mRNA expression but no type 1 receptor (Bdkrb1). Double-immunofluorescence staining for BDKRB2 and the anion exchanger AE2 (a marker of efferent duct ciliated cells) or the V-ATPase E subunit, official symbol ATP6V1E1 (a marker of epididymal clear cells), showed that BDKRB2 is expressed in the apical pole of nonciliated cells (efferent ducts) and principal cells (epididymis). Triple labeling for BDKRB2, AQP9, and ATP6V1E1 showed that BDKRB2 and AQP9 colocalize in the apical stereocilia of principal cells in the cauda epididymidis. While uniform Bdkrb2 mRNA expression was detected in the efferent ducts and along the epididymal tubule, marked variations were detected at the protein level. BDKRB2 was highest in the efferent ducts and cauda epididymidis, intermediate in the distal initial segment, moderate in the corpus, and undetectable in the proximal initial segment and the caput. Functional assays on tubules isolated from the distal initial segments showed that BK significantly increased AQP9-dependent glycerol apical membrane permeability. This effect was inhibited by BAPTA-AM, demonstrating the participation of calcium in this process. This study, therefore, identifies BK as an important regulator of AQP9. PMID:18829705

  12. 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.

  13. Synergistic activation of defense responses in Arabidopsis by simultaneous loss of the GSL5 callose synthase and the EDR1 protein kinase.

    PubMed

    Wawrzynska, Anna; Rodibaugh, Natalie L; Innes, Roger W

    2010-05-01

    Loss-of-function mutations in the EDR1 gene of Arabidopsis confer enhanced resistance to Golovinomyces cichoracearum (powdery mildew). Disease resistance mediated by the edr1 mutation is dependent on an intact salicylic acid (SA) signaling pathway, but edr1 mutant plants do not constitutively express the SA-inducible gene PR-1 and are not dwarfed. To identify other components of the EDR1 signaling network, we screened for mutations that enhanced the edr1 mutant phenotype. Here, we describe an enhancer of edr1 mutant, eed3, which forms spontaneous lesions in the absence of pathogen infection, constitutively expresses both SA- and methyl jasmonate (JA)-inducible defense genes, and is dwarfed. Positional cloning of eed3 revealed that the mutation causes a premature stop codon in GLUCAN SYNTHASE-LIKE 5 (GSL5, also known as POWDERY MILDEW RESISTANT 4), which encodes a callose synthase required for pathogen-induced callose production. Significantly, gsl5 single mutants do not constitutively express PR-1 or AtERF1 (a JA-inducible gene) and are not dwarfed. Thus, loss of both EDR1 and GSL5 function has a synergistic effect. Our data suggest that EDR1 and GSL5 negatively regulate SA and JA production or signaling by independent mechanisms and that negative regulation of defense signaling by GSL5 may be independent of callose production.

  14. Synergistic Activation of Defense Responses in Arabidopsis by Simultaneous Loss of the GSL5 Callose Synthase and the EDR1 Protein Kinase

    PubMed Central

    Wawrzynska, Anna; Rodibaugh, Natalie L.; Innes, Roger W.

    2012-01-01

    Loss-of-function mutations in the EDR1 gene of Arabidopsis confer enhanced resistance to Golovinomyces cichoracearum (powdery mildew). Disease resistance mediated by the edr1 mutation is dependent on an intact salicylic acid (SA) signaling pathway, but edr1 mutant plants do not constitutively express the SA-inducible gene PR-1, and are not dwarfed. To identify other components of the EDR1 signaling network, we screened for mutations that enhanced the edr1 mutant phenotype. Here we describe an enhancer of edr1 mutant, eed3, which forms spontaneous lesions in the absence of pathogen infection, constitutively expresses both SA and methyl-jasmonate (JA) inducible defense genes and is dwarfed. Positional cloning of eed3 revealed that the mutation causes a premature stop codon in GLUCAN SYNTHASE-LIKE 5 (GSL5, also known as POWDERY MILDEW RESISTANT 4, PMR4), which encodes a callose synthase required for pathogen-induced callose production. Significantly, gsl5 single mutants do not constitutively express PR-1 or AtERF1 (a JA-inducible gene) and are not dwarfed. Thus, loss of both EDR1 and GSL5 function has a synergistic effect. Our data suggest that EDR1 and GSL5 negatively regulate SA and JA production and/or signaling by independent mechanisms, and that negative regulation of defense signaling by GSL5 may be independent of callose production. PMID:20367466

  15. 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.

  16. Microstructural callosal abnormalities in normal-appearing brain of children with developmental delay detected with diffusion tensor imaging.

    PubMed

    Ding, Xiao-Qi; Sun, Yimeng; Kruse, Bernd; Illies, Till; Zeumer, Hermann; Fiehler, Jens; Lanfermann, Heinrich

    2009-06-01

    Callosal fibres play an important role in psychomotor and cognitive functions. The purpose of this study was to investigate possible microstructural abnormalities of the corpus callosum in children with developmental delay, who have normal conventional brain MR imaging results. Seventeen pediatric patients (aged 1-9 years) with developmental delay were studied. Quantitative T2 and fractional anisotropy (FA) values were measured at the genu and splenium of the corpus callosum (CC). Fibre tracking, volumetric determination, as well as fibre density calculations of the CC were also carried out. The results were compared with those of the age-matched healthy subjects. A general elevation of T2 relaxation times (105 ms in patients vs. 95 ms in controls) and reduction of the FA values (0.66 in patients vs. 0.74 in controls) at the genu of the CC were found in patients. Reductions of the fibre numbers (5,464 in patients vs. 8,886 in controls) and volumes (3,415 ml in patients vs. 5,235 ml in controls) of the CC were found only in patients older than 5 years. The study indicates that despite their inconspicuous findings in conventional MRI microstructural brain abnormalities are evident in these pediatric patients suffering from developmental delay.

  17. Effects of callosal agenesis on rotational side preference of BALB/cCF mice in the free swimming test.

    PubMed

    Filgueiras, Cláudio C; Manhães, Alex C

    2004-11-05

    In order to test the hypothesis that the ontogenetic development of the corpus callosum is related to the establishment of behavioral laterality, the rotatory behavior in the free swimming test was studied in male mice of the BALB/cCF strain, in which approximately 20% of the animals present total or partial callosal agenesis. All animals were submitted to three sessions of the free-swimming rotatory test in three different sessions (diameter of the recipient = 21 cm; session duration = 5 min; inter-test interval = 48 h). The number and direction of the 30 and 360 degrees turns were recorded. Animals were classified as side-consistent turners (to the right or to the left) when they did not change their preferred side of rotation in all three sessions and in both turning units. In general our results suggested that acallosal animals present more pronounced laterality than normal ones. In the acallosal group, the percentage of consistent turners was significantly higher than that of non-consistent turners. The percentage of animals that presented strong turning preferences in the acallosal group was higher than in the normal group. In first session, the acallosal group presented a higher average number of turns to preferred side than the normal group. Taken together, our results constitute an endorsement to the hypothesis that the normal development of the corpus callosum is related to the establishment of cerebral laterality.

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

    PubMed

    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

    2012-02-01

    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.

  19. Effects of 3-beta-diol, an androgen metabolite with intrinsic estrogen-like effects, in modulating the aquaporin-9 expression in the rat efferent ductules

    PubMed Central

    Picciarelli-Lima, Patrícia; Oliveira, André G; Reis, Adelina M; Kalapothakis, Evanguedes; Mahecha, Germán AB; Hess, Rex A; Oliveira, Cleida A

    2006-01-01

    Background Fluid homeostasis is critical for normal function of the male reproductive tract and aquaporins (AQP) play an important role in maintenance of this water and ion balance. Several AQPs have been identified in the male, but their regulation is not fully comprehended. Hormonal regulation of AQPs appears to be dependent on the steroid in the reproductive tract region. AQP9 displays unique hormonal regulation in the efferent ductules and epididymis, as it is regulated by both estrogen and dihydrotestosterone (DHT) in the efferent ductules, but only by DHT in the initial segment epididymis. Recent data have shown that a metabolite of DHT, 5-alpha-androstane-3-beta-17-beta-diol (3-beta-diol), once considered inactive, is also present in high concentrations in the male and indeed has biological activity. 3-beta-diol does not bind to the androgen receptor, but rather to estrogen receptors ER-alpha and ER-beta, with higher affinity for ER-beta. The existence of this estrogenic DHT metabolite has raised the possibility that estradiol may not be the only estrogen to play a major role in the male reproductive system. Considering that both ER-alpha and ER-beta are highly expressed in efferent ductules, we hypothesized that the DHT regulation of AQP9 could be due to the 3-beta-diol metabolite. Methods To test this hypothesis, adult male rats were submitted to surgical castration followed by estradiol, DHT or 3-beta-diol replacement. Changes in AQP9 expression in the efferent ductules were investigated by using immunohistochemistry and Western blotting assay. Results Data show that, after castration, AQP9 expression was significantly reduced in the efferent ductules. 3-beta-diol injections restored AQP9 expression, similar to DHT and estradiol. The results were confirmed by Western blotting assay. Conclusion This is the first evidence that 3-beta-diol has biological activity in the male reproductive tract and that this androgen metabolite has estrogen-like activity in

  20. Expression of aquaporins in the efferent ductules, sperm counts, and sperm motility in estrogen receptor-alpha deficient mice fed lab chow versus casein.

    PubMed

    Ruz, Ricardo; Gregory, Mary; Smith, Charles E; Cyr, Daniel G; Lubahn, Dennis B; Hess, Rex A; Hermo, Louis

    2006-02-01

    Estrogens play an important role in the male reproductive tract, and this is especially so for the efferent ductules, where alpha-estrogen receptors (ERalpha) have been localized. Mice deficient in ERalpha (alphaERKO mice) are infertile, and the effect appears to be due in part to retention of water at the level of the efferent ductules. In the present study, we examined the consequences of ERalpha deletion on the distribution of certain aquaporins (AQPs), water protein channels, in the efferent ductules and on sperm numbers and motility. In addition, the effects of feeding mice a regular lab chow diet, which contains phytoestrogens, known to affect male reproductive tract functions, and a casein diet, which lacks phytoestrogens, were also assessed. Light microscope immunolocalizations of AQP-1 and AQP-9 revealed dramatic reduction and patchier staining in alphaERKO mice with distal areas of the efferent ductules being more affected than proximal areas. No other changes in immunolocalizations were noted as a consequence of diet. Computer-assisted sperm analyses demonstrated a 62% reduction in cauda epididymal sperm/ml in alphaERKO mice fed lab chow, whereas 87% fewer sperm/ml were observed in alphaERKO mice fed casein, suggesting an enhanced role for sperm production and concentration in a diet containing phytoestrogens. All sperm motility parameters were altered to some degree in alphaERKO mice fed lab chow. Alterations in sperm motility parameters were also detected, but were less dramatic in alphaERKO mice fed casein. These data suggest that the decrease in AQP expression in the efferent ductules of alphaERKO mice contributes in part to water retention in this tissue, eventually leading to backflow of water into the testis, with subsequent decreases in sperm concentration and motility. The data also suggest that phytoestrogens, which are present in regular lab chow, can influence the male reproductive tract with and without the presence of ERalpha, promoting

  1. 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

  2. Cool & Connected

    EPA Pesticide Factsheets

    The Cool & Connected planning assistance program helps communities develop strategies and an action plan for using broadband to promote environmentally and economically sustainable community development.

  3. Comparison of morphological changes in efferent lymph nodes after implantation of resorbable and non-resorbable implants in rabbits

    PubMed Central

    2011-01-01

    Background Magnesium alloys as biodegradable implant materials received much interest in recent years. It is known that products of implant degradation can induce several types of immune response. Hence, the aim of this study was to examine the morphological changes of efferent lymph nodes after implantation of different resorbable magnesium alloys (MgCa0.8, LAE442) in comparison to commercially available resorbable (PLA) and non-resorbable (titanium) implant materials as well as control groups without implant material. Methods The different implant materials were inserted intramedullary into the rabbit tibia. After postoperative observation periods of three and six months, popliteal lymph nodes were examined histologically and immunhistologically and compared to lymph nodes of sham operated animals and animals without surgery. Haematoxylin and eosin staining was performed for cell differentiation. Mouse anti-CD79α and rat anti-CD3 monoclonal primary antibodies were used for B- and T-lymphocyte detection, mouse anti-CD68 primary antibodies for macrophage detection. Evaluation of all sections was performed applying a semi quantitative score. Results The histological evaluation demonstrated low and moderate levels of morphological changes for both magnesium alloys (LAE442 and MgCa0.8). Higher than moderate values were reached for titanium in sinus histiocytosis and histiocytic apoptosis (3 months) and for PLA in histiocytic apoptosis (3 and 6 months). The immune response to all investigated implants had a non-specific character and predominantly was a foreign-body reaction. LAE442 provoked the lowest changes which might be due to a lower degradation rate in comparison to MgCa0.8. Therewith it is a promising candidate for implants with low immunogenic potential. Conclusion Both examined magnesium alloys did not cause significantly increased morphological changes in efferent lymph nodes in comparison to the widely used implant materials titanium and PLA. LAE442

  4. Morphofunctional alterations in the olivocochlear efferent system of the genetic audiogenic seizure-prone hamster GASH:Sal.

    PubMed

    Sánchez-Benito, David; Gómez-Nieto, Ricardo; Hernández-Noriega, Sonia; Murashima, Adriana Andrade Batista; de Oliveira, José Antonio Cortes; Garcia-Cairasco, Norberto; López, Dolores E; Hyppolito, Miguel Angelo

    2017-06-01

    The genetic audiogenic seizure hamster (GASH:Sal) is a model of a form of reflex epilepsy that is manifested as generalized tonic-clonic seizures induced by external acoustic stimulation. The morphofunctional alterations in the auditory system of the GASH:Sal that may contribute to seizure susceptibility have not been thoroughly determined. In this study, we analyzed the olivocochlear efferent system of the GASH:Sal from the organ of Corti, including outer and inner hair cells, to the olivocochlear neurons, including shell, lateral, and medial olivocochlear (LOC and MOC) neurons that innervate the cochlear receptor. To achieve this, we carried out a multi-technical approach that combined auditory hearing screenings, scanning electron microscopy, morphometric analysis of labeled LOC and MOC neurons after unilateral Fluoro-Gold injections into the cochlea, and 3D reconstruction of the lateral superior olive (LSO). Our results showed that the GASH:Sal exhibited higher auditory brain response (ABR) thresholds than their controls, as well as absence of distortion-product of otoacoustic emissions (DPOAEs) in a wide range of frequencies. The ABR and DPOAE results also showed differences between the left and right ears, indicating asymmetrical hearing alterations in the GASH:Sal. These alterations in the peripheral auditory activity correlated with morphological alterations. At the cochlear level, the scanning electron microscopy analysis showed marked distortions of the stereocilia from basal to apical cochlear turns in the GASH:Sal, which were not observed in the control hamsters. At the brainstem level, MOC, LOC, and shell neurons had reduced soma areas compared with control animals. This LOC neuron shrinkage contributed to reduction in the LSO volume of the GASH:Sal as shown in the 3D reconstruction analysis. Our study demonstrated that the morphofunctional alterations of the olivocochlear efferent system are innate components of the GASH:Sal, which might contribute to

  5. 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

  6. 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.…

  7. Regular connections among generalized connections

    NASA Astrophysics Data System (ADS)

    Fleischhack, Christian

    2003-09-01

    The properties of the space A of regular connections as a subset of the space Ā of generalized connections in the Ashtekar framework are studied. For every choice of compact structure group and smoothness category for the paths, it is determined whether A is dense in Ā or not. Moreover, it is proven that A has Ashtekar-Lewandowski measure zero for every non-trivial structure group and every smoothness category. The analogous results hold for gauge orbits instead of connections.

  8. Inhibition by efferent nerve fibres: action on hair cells and afferent synaptic transmission in the lateral line canal organ of the burbot Lota lota.

    PubMed Central

    Flock, A; Russell, I

    1976-01-01

    1. Intracellular recordings were made from morphologically identified hair cells in the lateral line canal organs of the burbot Lota lota. 2. I.p.s.p.s were recorded from hair cells when the efferent fibres were excited by electrical stimulation of the lateral line nerve. The i.p.s.p.s were abolished when the fish was injected with immobilizing concentration of Flaxedil which is known to block the efferent synapses. 3. The i.p.s.p.s are accompanied by a decrease in the resistance of the hair cell membrane and an increase in the intracellular receptor potential. 4. Spontaneous and mechanically evoked e.p.s.p.s which were recorded intracellularly from the post-synaptic afferent nerve terminals were reduced in amplitude for the duration of the i.p.s.p. Images A, B C PMID:948076

  9. Evoked potential study of hippocampal efferent projections in the human brain.

    PubMed

    Catenoix, H; Magnin, M; Mauguière, F; Ryvlin, P

    2011-12-01

    To explore in human potential hippocampal projections within and outside the temporal lobe. We performed intra-cerebral electrical stimulations in seven patients investigated by depth electrodes for refractory epilepsy and analyzed the presence of evoked potentials (EPs) in all brain regions explored. Bipolar electrical stimulations, consisting of two series of 25 pulses of 1 ms duration, 0.2 Hz frequency, and 3 mA intensity, were delivered in a total of 36 hippocampal stimulations sites. Reproducible EPs were recorded in several brain regions with variable latencies, amplitudes and morphologies. Within the temporal lobe, EPs were present in the amygdala, entorhinal cortex, temporal pole and temporal neocortex. EPs were also observed in the frontal lobe, anterior cingulate gyrus and orbito-frontal cortex, midcingulate and posterior cingulate gyrus, insula and thalamic pulvinar nucleus. Our results demonstrate a large distribution of direct or indirect hippocampal projections. This widespread connectivity supports the previous definition of different networks involved mainly in memory and behavioral processes, implicating the temporal lobe, the cingulate gyrus or the prefrontal region. Our data provide some clues to further evaluate potential pathways of propagation of mesial temporal lobe seizure, via the insula or the pulvinar nucleus. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  10. The evolution of efferent vagal control of the heart in vertebrates.

    PubMed

    Taylor, E W

    1994-09-01

    In vertebrates vagal preganglionic neurons are found in two principle locations in the brain-stem, the dorsal vagal motor nucleus and areas lateral to the dorsal vagal motor nucleus centered on the nucleus ambiguus. In elasmobranch fish 8% of vagal preganglionic neurons are located outside the dorsal vagal motor nucleus; these are all cardiac vagal motoneurones. This proportion increases from fish through amphibians to mammals in which over 30% of vagal preganglionic neurons are outside the dorsal vagal motor nucleus; in the cat 80% of cardiac vagal motoneurons are in the nucleus ambiguus. Vagal tone is the major determinant of heart rate and its relationships to environmental factors (e.g. temperature, hypoxia). Activity in subpopulations of cardiac vagal motoneurons varies with the respiratory rhythm in fish and mammals due to central interactions between respiratory and cardiac vagal motoneurons. This generates cardio-respiratory synchrony in dogfish and respiratory sinus arrhythmia in mammals. The appropriate central connections are established during development. In the neotenous axolotl all vagal preganglionic neurons are in the dorsal vagal motor nucleus; 15% are lateral to the dorsal vagal motor nucleus following metamorphosis, induced by injection of thyroid hormones; a change which may relate in part to the switch from gill to lung-breathing. Respiratory sinus arrhythmia first appears at around normal term gestation in the premature human neonate, at a time when they would normally be switching from reliance on the placenta to lung-breathing.

  11. 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.

  12. Neuroanatomical evidence for a role of central melanocortin-4 receptors and oxytocin in the efferent control of the rodent clitoris and vagina.

    PubMed

    Gelez, Helene; Poirier, Sarah; Facchinetti, Patricia; Allers, Kelly A; Wayman, Chris; Alexandre, Laurent; Giuliano, François

    2010-06-01

    The clitoris and the vagina are the main peripheral anatomical structures involved in physiological changes related to sexual arousal and orgasm. Their efferent control and, more particularly, the neurochemical phenotype of these descending neuronal pathways remain largely uncharacterized. To examine if brain neurons involved in the efferent control of the clitoris and the vagina possess melanocortin-4 receptor (MC4-R) and/or contain oxytocin (OT). Neurons involved in the efferent control of the vagina and clitoris were identified following visualization of pseudorabies virus (PRV) retrograde tracing. PRV was injected into the vagina and clitoris in adult rats in estrous. On the fifth day postinjection, animals were humanely sacrificed, and brains were removed and sectioned, and processed for PRV visualization. The neurochemical phenotype of PRV-positive neurons was identified using double or triple immunocytochemical labeling against PRV, MC4-R, and OT. Double and triple labeling were quantified using confocal laser scanning microscopy. Neuroanatomical brain distribution, number and percentage of double-labeled PRV/MC4-R and PRV-/OT-positive neurons, and triple PRV-/MC4-R-/OT-labeled neurons. The majority of PRV immunopositive neurons which also expressed immunoreactivity for MC4-R were located in the paraventricular and arcuate nuclei of the hypothalamus. The majority of PRV positive neurons which were immunoreactive (IR) for OT were located in the paraventricular nucleus (PVN), medial preoptic area (MPOA), and lateral hypothalamus. PRV positive neurons were more likely to be IR for MC4-R than for OT. Scattered triple-labeled PRV/MC4-R/OT neurons were detected in the MPOA and the PVN. These data strongly suggest that MC4-R and, to a less extent, OT are involved in the efferent neuronal control of the clitoris and vagina, and consequently facilitate our understanding of how the melanocortinergic pathway regulates female sexual function.

  13. 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.

  14. 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.

  15. Differential role of afferent and efferent renal nerves in the maintenance of early- and late-phase Dahl S hypertension

    PubMed Central

    Foss, Jason D.; Fink, Gregory D.

    2015-01-01

    Clinical data suggest that renal denervation (RDNX) may be an effective treatment for human hypertension; however, it is unclear whether this therapeutic effect is due to ablation of afferent or efferent renal nerves. We have previously shown that RDNX lowers arterial pressure in hypertensive Dahl salt-sensitive (S) rats to a similar degree observed in clinical trials. In addition, we have recently developed a method for selective ablation of afferent renal nerves (renal-CAP). In the present study, we tested the hypothesis that the antihypertensive effect of RDNX in the Dahl S rat is due to ablation of afferent renal nerves by comparing the effect of complete RDNX to renal-CAP during two phases of hypertension in the Dahl S rat. In the early phase, rats underwent treatment after 3 wk of high-NaCl feeding when mean arterial pressure (MAP) was ∼140 mmHg. In the late phase, rats underwent treatment after 9 wk of high NaCl feeding, when MAP was ∼170 mmHg. RDNX reduced MAP ∼10 mmHg compared with sham surgery in both the early and late phase, whereas renal-CAP had no antihypertensive effect. These results suggest that, in the Dahl S rat, the antihypertensive effect of RDNX is not dependent on pretreatment arterial pressure, nor is it due to ablation of afferent renal nerves. PMID:26661098

  16. Excessive activation of ionotropic glutamate receptors induces apoptotic hair-cell death independent of afferent and efferent innervation

    PubMed Central

    Sheets, Lavinia

    2017-01-01

    Accumulation of excess glutamate plays a central role in eliciting the pathological events that follow intensely loud noise exposures and ischemia-reperfusion injury. Glutamate excitotoxicity has been characterized in cochlear nerve terminals, but much less is known about whether excess glutamate signaling also contributes to pathological changes in sensory hair cells. I therefore examined whether glutamate excitotoxicity damages hair cells in zebrafish larvae exposed to drugs that mimic excitotoxic trauma. Exposure to ionotropic glutamate receptor (iGluR) agonists, kainic acid (KA) or N-methyl-D-aspartate (NMDA), contributed to significant, progressive hair cell loss in zebrafish lateral-line organs. To examine whether hair-cell loss was a secondary effect of excitotoxic damage to innervating neurons, I exposed neurog1a morphants—fish whose hair-cell organs are devoid of afferent and efferent innervation—to KA or NMDA. Significant, dose-dependent hair-cell loss occurred in neurog1a morphants exposed to either agonist, and the loss was comparable to wild-type siblings. A survey of iGluR gene expression revealed AMPA-, Kainate-, and NMDA-type subunits are expressed in zebrafish hair cells. Finally, hair cells exposed to KA or NMDA appear to undergo apoptotic cell death. Cumulatively, these data reveal that excess glutamate signaling through iGluRs induces hair-cell death independent of damage to postsynaptic terminals. PMID:28112265

  17. 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.

  18. 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.

  19. Postnatal development of corticocortical efferents from area 17 in the cat's visual cortex

    SciTech Connect

    Price, D.J.; Zumbroich, T.J.

    1989-02-01

    We are interested in the postnatal development of corticocortical connections in the cat's visual cortex. In this study, we injected the anterograde tracer 3H-proline into visual cortical area 17 of kittens, aged 4-70 d, and adult cats to visualize the distribution of terminals of the association projections to areas 18, 19, 21a, and the lateral suprasylvian visual cortex. The density of anterograde label was quantified using computerized image analysis. There was dense labeling at topographically appropriate locations in area 18 in animals of all ages. In 4- and 8-d-old kittens, other extrastriate areas (19, 21a and the lateral suprasylvian cortex) contained only sparse label, localized in a few solitary axons; these areas were densely labeled in animals aged 12 d or more. In kittens aged 4-20 d there was considerable, widespread label within fibers located in the white matter, and many of these axons lay underneath regions of extrastriate, and also striate, cortex that were almost certainly not destined to be persistently innervated by cells at the injection site. This pattern of extensive white matter label was not seen in animals older than 20 d. In each extrastriate region, from the earliest age at which we identified dense cortical innervation from area 17, the terminals were distributed in clusters. At first these patches were mainly in infragranular layers, but later, during the second and third postnatal weeks, they began to appear in more superficial laminae. By 70 d, an adult-like distribution of terminals was found in each extrastriate area: most fibers appeared to end in layers II and III in areas 18, 19, and 21a and centered on layer IV in the medial bank of the middle suprasylvian sulcus in adult cats. We suggest that the development of ipsilateral association projections from area 17 to extrastriate cortex is a 2-stage process.

  20. 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)

  1. The centrally projecting Edinger-Westphal nucleus--I: Efferents in the rat brain.

    PubMed

    Dos Santos Júnior, Edmilson D; Da Silva, André V; Da Silva, Kelly R T; Haemmerle, Carlos A S; Batagello, Daniella S; Da Silva, Joelcimar M; Lima, Leandro B; Da Silva, Renata J; Diniz, Giovanne B; Sita, Luciane V; Elias, Carol F; Bittencourt, Jackson C

    2015-10-01

    The oculomotor accessory nucleus, often referred to as the Edinger-Westphal nucleus [EW], was first identified in the 17th century. Although its most well known function is the control of pupil diameter, some controversy has arisen regarding the exact location of these preganglionic neurons. Currently, the EW is thought to consist of two different parts. The first part [termed the preganglionic EW-EWpg], which controls lens accommodation, choroidal blood flow and pupillary constriction, primarily consists of cholinergic cells that project to the ciliary ganglion. The second part [termed the centrally projecting EW-EWcp], which is involved in non-ocular functions such as feeding behavior, stress responses, addiction and pain, consists of peptidergic neurons that project to the brainstem, the spinal cord and prosencephalic regions. However, in the literature, we found few reports related to either ascending or descending projections from the EWcp that are compatible with its currently described functions. Therefore, the objective of the present study was to systematically investigate the ascending and descending projections of the EW in the rat brain. We injected the anterograde tracer biotinylated dextran amine into the EW or the retrograde tracer cholera toxin subunit B into multiple EW targets as controls. Additionally, we investigated the potential EW-mediated innervation of neuronal populations with known neurochemical signatures, such as melanin-concentrating hormone in the lateral hypothalamic area [LHA] and corticotropin-releasing factor in the central nucleus of the amygdala [CeM]. We observed anterogradely labeled fibers in the LHA, the reuniens thalamic nucleus, the oval part of the bed nucleus of the stria terminalis, the medial part of the central nucleus of the amygdala, and the zona incerta. We confirmed our EW-LHA and EW-CeM connections using retrograde tracers. We also observed moderate EW-mediated innervation of the paraventricular nucleus of the

  2. The central adrenergic system. An immunofluorescence study of the location of cell bodies and their efferent connections in the rat utilizing dopamine-beta-hydroxylase as a marker.

    PubMed

    Swanson, L W; Hartman, B K

    1975-10-15

    A sensitive immunofluorescence technique was used to describe systematically the distrubution of dopamine-beta-hydroxylase (DBH)-containing cell bodies, non-terminal fiber pathways, and terminal fields in the brain of the male albino rat. DBH is the enzyme that catalyzes the conversion of dopamine to noradrenaline, and as such is useful as an anatomical marker for noradrenaline and possibly adrenaline neurons. The enzyme is not present in dopamine- or indolamine-containing neurons. Ten micron frozen sections (1-in 20 series) were prepared in the frontal, sagittal, and horizontal planes from the olfactory bulb to the upper cervical segments of the spinal cord; adjacent sections in each plane were stained for DBH and for cells (toluidine blue=azure II). An atlas consisting of 40 projection drawings of selected frontal sections illustrates the results of the investigation. DBH perikarya are confined to three groups in the pons and medulla: the well defined locus coeruleus, a more diffuse but continuous subcoeruleus group that arches through the pons and ventral medulla, and a third dorsal medullary group centered in the dorsal motor nucleus of the vagus. A single principal adrenergic fiber system distributes a great many of the axons from these neuron groups to a majority of nuclear areas in the brain. In the pons and medulla two components of the fiber system may be distinguished. A medullary branch may be followed from the posterior aspect of the subcoeruleus group dorsally and then anteriorly through the lateral tegmental field and ventral aspect of the vestibular complex to a position subjacent to the locus coeruleus, where it is joined by a subcoeruleus branch consisting of a large number of fibers coursing among cells along the length of the subcoeruleus group, and by fibers arising from the locus coeruleus. Anterior to the locus coeruleus the principal adrenergic bundle courses as a single fiber tract immediately ventrolateral to the central gray in the mesencephalon and in the zona incerta and substantia innominata in the diencephalon. At the level of the septal area separate bundles reach the cortex dorsally over the genu of the corpus calosum via the medial septal-diagonal band nuclei and the lateral septum and ventrally between the olfactory tubercle and caudate-putamen. In the medulla and pons adrenergic fibers undoubtedly course in both directions. Anterior to the most rostral pontine cell bodies, however, all fibers presumably ascend. Along the course of the bundle distinct branches emerge to innervate circumscribed terminal fields. In addition, certain regions of the brain such as the reticular formation and pontine gray receive diffuse DBH innervation derived from less clearly defined pathways. A small number of areas in the brain contain little or no detectable DBH. These include the caudate-putamen, nucleus accumbens, globus pallidus, olfactory tubercle, subthalamic nucleus, substantia nigra, pretectal area, third, fourth and sixth cranial verve nuclei, and the trapezoid body nucleus.

  3. Connections of the octopus optic lobe: an HRP study.

    PubMed

    Saidel, W M

    1982-04-20

    The major visual centers of the octopus central nervous system are the paired optic lobes. Bidirectional transport of horseradish peroxidase (HRP) was used to determine connections of the optic lobe. Cells afferent to the optic lobe were identified by retrograde HRP transport in the following lobes of the central ganglia: anterior basal, median basal, dorsal basal, interbasal, subvertical, precommissural, brachial, and magnocellular. Labeled cells were also observed within the contralateral optic lobe, various optic tract lobes bilaterally, and in photoreceptors of the ipsilateral retina. Additionally, individual fibers, in part originating from cells in the posterior subvertical lobe, were labeled within the central neuropil core of various vertical lobules. Differences in results between superficial and deep optic lobe medulla injections indicate that some afferent projections from central sources may terminate on cell populations at specific depths within the lobe. Efferent optic lobe fibers into the superior frontal and lateral basal lobes were labeled by anterograde transport. Other possible optic lobe efferent projections terminated in supraesophageal lobes and the magnocellular lobe. The many inputs to the optic lobe from higher motor and associative centers in the central ganglia emphasize that the medulla region of the optic lobe is an exceptionally complex integrative area.

  4. See-through Brains and Diffusion Tensor MRI Clarified Fiber Connections: A Preliminary Microstructural Study in a Mouse with Callosal Agenesis.

    PubMed

    Kerever, Aurelien; Kamagata, Koji; Yokosawa, Suguru; Otake, Yosuke; Ochi, Hisaaki; Yamada, Taihei; Hori, Masaaki; Kamiya, Kouhei; Nishikori, Akira; Aoki, Shigeki; Arikawa-Hirasawa, Eri

    2015-01-01

    Clearing methods that render the brain optically transparent allow high-resolution three-dimensional (3D) imaging of neural networks. We used diffusion tensor imaging (DTI) and two-photon imaging of cleared brains to analyze white matter in BTBR mice. We confirmed corpus callosum agenesis and identified an abnormal commissure close to the third ventricle. DTI and cleared-brain two-photon imaging revealed that these commissural fibers constituted a frontal clustering of the ventral hippocampal commissure and provided a detailed assessment of white matter structure in mice.

  5. Differential increases in P2X receptor levels in rat vagal efferent neurones following a vagal nerve section.

    PubMed

    Atkinson, Lucy; Shigetomi, Eiji; Kato, Fusao; Deuchars, Jim

    2003-07-04

    Extracellular ATP can influence cells via activation of P2X purinoceptors, the distribution of which can be altered in the central and peripheral nervous systems following injury or tissue damage. Here we have investigated the effect of a unilateral section of the cervical vagus nerve on the distribution of P2X(1), P2X(2), P2X(3), P2X(4) and P2X(7) receptor subunit immunoreactivity (R-IR) in the dorsal vagal motor nucleus (DVN) and the nucleus ambiguus (NA) in the medulla oblongata. As early as 2 days, and followed up to 14 days, there was a dramatic ipsilateral increase in P2X(1), P2X(2) and P2X(4)R-IR in the cell soma of vagal efferent neurones in the DVN following the nerve section, but not the NA. There were no changes in P2X(3) and P2X(7)R-IR in either nuclei. To test for possible functional consequences of increased P2X receptor levels, whole-cell patch-clamp recordings were made from DVN cells in brainstem slices 4 days following unilateral vagotomy. Application of ATP revealed large cell-to-cell variance in the current amplitude in neurones from both sectioned and control DVN. However, when ATP responses were compared to those elicited by the nicotinic acetylcholine receptor agonist carbachol, the mean ratio of the peak ATP-evoked current to the peak carbachol-evoked current was significantly larger in DVN neurones ipsilateral to the section. Thus the increase in P2XR levels in DVN cells ipsilateral to a nerve section are likely to reflect an increase in expression of functional P2XRs on the cell surface.

  6. Nitric oxide: a co-modulator of efferent peptidergic neurosecretory cells including a unique octopaminergic neurone innervating locust heart.

    PubMed

    Bullerjahn, Alexander; Mentel, Tim; Pflüger, Hans-Joachim; Stevenson, Paul A

    2006-08-01

    Our findings suggest that nitric oxide (NO) acts as peripheral neuromodulator in locusts, in which it is commonly co-localized with RF-like peptide in neurosecretory cells. We also present the first evidence for NO as a cardio-regulator in insects. Putative NO-producing neurones were detected in locust pre-genital free abdominal ganglia by NADPH-diaphorase histochemistry and with an antibody against NO synthase (NOS). With both methods, we identified the same 14 somata in each examined ganglion: two dorsal posterior midline somata; six ventral posterior midline somata; and three pairs of lateral somata. A combination of NOS-detection methods with nerve tracing and transmitter immunocytochemistry revealed that at least 12 of these cells were efferent, of which four were identified as peptidergic neurosecretory cells with an antiserum detecting RFamide-like peptides. One of the latter was unequivocally identified as an octopaminergic dorsal unpaired median (DUM) neurone, which specifically projected to the heart ("DUM-heart"). Its peripheral projections revealed by axon tracing appeared as a meshwork of varicose endings encapsulating the heart. NOS-like immunoreactive profiles were found in the heart nerve. NO donors caused a dose-dependent increase in heart rate. This cardio-excitatory effect was negatively correlated to resting heart rate and seemed to be dependent on the physiological state of the animal. Hence, NO released from neurones such as the rhythmically active DUM-heart might exert continuous control over the heart. Possible mechanisms for the actions of NO on the heart and interactions with other neuromodulators co-localized in the DUM-heart neurone (octopamine, taurine, RF-amide-like peptide) are discussed.

  7. Connected Traveler

    SciTech Connect

    2016-06-01

    The Connected Traveler framework seeks to boost the energy efficiency of personal travel and the overall transportation system by maximizing the accuracy of predicted traveler behavior in response to real-time feedback and incentives. It is anticipated that this approach will establish a feedback loop that 'learns' traveler preferences and customizes incentives to meet or exceed energy efficiency targets by empowering individual travelers with information needed to make energy-efficient choices and reducing the complexity required to validate transportation system energy savings. This handout provides an overview of NREL's Connected Traveler project, including graphics, milestones, and contact information.

  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. 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.

  10. Tie-dyed2 encodes a callose synthase that functions in vein development and affects symplastic trafficking within the phloem of maize leaves.

    PubMed

    Slewinski, Thomas L; Baker, R Frank; Stubert, Adam; Braun, David M

    2012-11-01

    The tie-dyed2 (tdy2) mutant of maize (Zea mays) displays variegated green and yellow leaves. Intriguingly, the yellow leaf tissues hyperaccumulate starch and sucrose, the soluble sugar transported long distance through the phloem of veins. To determine the molecular basis for Tdy2 function, we cloned the gene and found that Tdy2 encodes a callose synthase. RNA in situ hybridizations revealed that in developing leaves, Tdy2 was most highly expressed in the vascular tissue. Comparative expression analysis with the vascular marker maize PINFORMED1a-yellow fluorescent protein confirmed that Tdy2 was expressed in developing vein tissues. To ascertain whether the defect in tdy2 leaves affected the movement of sucrose into the phloem or its long-distance transport, we performed radiolabeled and fluorescent dye tracer assays. The results showed that tdy2 yellow leaf regions were defective in phloem export but competent in long-distance transport. Furthermore, transmission electron microscopy of tdy2 yellow leaf regions showed incomplete vascular differentiation and implicated a defect in cell-to-cell solute movement between phloem companion cells and sieve elements. The disruption of sucrose movement in the phloem in tdy2 mutants provides evidence that the Tdy2 callose synthase functions in vascular maturation and that the vascular defects result in impaired symplastic trafficking into the phloem translocation stream.

  11. Callose and cellulose synthase gene expression analysis from the tight cluster to the full bloom stage and during early fruit development in Malus × domestica.

    PubMed

    Guerriero, Gea; Giorno, Filomena; Folgado, Raquel; Printz, Bruno; Baric, Sanja; Hausman, Jean-Francois

    2014-01-01

    Apple (Malus × domestica) is an economically important temperate fruit-bearing crop which belongs to the family of Rosaceae and its pomaceous fruit is one of the most commonly cultivated. Several studies have demonstrated that the cell wall plays a pivotal role during flower and fruit development. It takes active part in pollen tube growth and contributes to determine the fruit firmness trait through the action of cell wall-related enzymes (i.e. polygalacturonase and pectinmethylesterase). We have investigated the expression of callose and cellulose synthase genes during flowering from tight cluster to anthesis and during early fruit development in domesticated apple. We also link the changes observed in gene expression to the profile of soluble non-structural carbohydrates at different developmental stages of flowers/fruitlets and to the qualitative results linked to wall polysaccharides' composition obtained through near-infrared spectroscopy. This work represents an important addition to the study of tree physiology with respect to the analysis of the expression of callose and cellulose synthase genes during flower and early fruit development in domesticated apple.

  12. Callosal size in first-episode schizophrenia patients with illness duration of less than one year: A cross-sectional MRI study.

    PubMed

    Takahashi, Michio; Matsui, Mie; Nakashima, Mitsuhiro; Takahashi, Tsutomu; Suzuki, Michio

    2017-02-01

    Previous studies have reported a reduction in the size of the corpus callosum (CC) on the mid-sagittal plane in patients with schizophrenia. However, findings for the size of the callosal area in patients with first-episode schizophrenia (FESz) are inconsistent. A possibility for these conflicting results is that the duration of illness in patients with FESz affects the CC size. The present study investigated the CC size abnormalities in patients with FESz. Forty-six patients with FESz whose duration of illness was less than 1year and 46 age-, sex-, and handedness-matched healthy controls were recruited to examine the CC size using magnetic resonance imaging. We measured the area of the CC using the Witelson's scheme, which divided the whole area into seven subdivisions. Analysis of covariance indicated there was no difference in the whole or regional areas of the CC between patients with FESz and healthy controls. The rostrum of the CC was significantly correlated with the total score for negative symptoms and some of the subtotal scores. Our findings indicate that there was no reduction in the whole or regional area of the CC among patients with FESz. When comparing the callosal morphology and symptoms, negative symptoms increased in severity as the rostrum area of the CC decreased in size. Further studies are needed to investigate whether the size of the anterior CC is associated with the pathology observed in the early stages of FESz.

  13. Influence of Free Fatty Acids, Lysophosphatidylcholine, Platelet-Activating Factor, Acylcarnitine, and Echinocandin B on 1,3-β-d-Glucan Synthase and Callose Synthesis 1

    PubMed Central

    Kauss, Heinrich; Jeblick, Wolfgang

    1986-01-01

    The activity of 1,3-β-d-glucan synthase assayed in the presence of digitonin in a microsomal preparation from suspension-cultured cells of Glycine max can be fully inhibited by unsaturated fatty acids, trienoic acids being most effective. Lysophosphatidylcholine, platelet-activating factor, acylcarnitine, and Echinocandin B can also fully inhibit the enzyme. Inhibition is observed both when the enzyme is activated by Ca2+ or by trypsinization. At low amounts some of the substances can also cause stimulation. These effects all may result from a displacement of certain endogenous phospholipids necessary for optimal activity of the 1,3-β-d-glucan synthase. In the absence of digitonin the enzyme activity is greatly stimulated by lysophosphatidylcholine, platelet-activating factor, acylcarnitine, and Echinocandin B within a certain concentration range, presumably by rendering the microsomal vesicles permeable to the substrate and Ca2+. Dibucaine does not cause such an effect. Acylcarnitine and Echinocandin B at low concentrations can induce callose synthesis in vivo; this effect is enhanced by chitosan. At higher concentrations the two substances and polyunsaturated fatty acids cause severe electrolyte leakage. The effects are discussed in regard to the induction of callose synthesis by enforced Ca2+ influx, and its modulation by membrane lipids. PMID:16664610

  14. Tie-dyed2 Encodes a Callose Synthase That Functions in Vein Development and Affects Symplastic Trafficking within the Phloem of Maize Leaves12[C][W][OA

    PubMed Central

    Slewinski, Thomas L.; Baker, R. Frank; Stubert, Adam; Braun, David M.

    2012-01-01

    The tie-dyed2 (tdy2) mutant of maize (Zea mays) displays variegated green and yellow leaves. Intriguingly, the yellow leaf tissues hyperaccumulate starch and sucrose, the soluble sugar transported long distance through the phloem of veins. To determine the molecular basis for Tdy2 function, we cloned the gene and found that Tdy2 encodes a callose synthase. RNA in situ hybridizations revealed that in developing leaves, Tdy2 was most highly expressed in the vascular tissue. Comparative expression analysis with the vascular marker maize PINFORMED1a-yellow fluorescent protein confirmed that Tdy2 was expressed in developing vein tissues. To ascertain whether the defect in tdy2 leaves affected the movement of sucrose into the phloem or its long-distance transport, we performed radiolabeled and fluorescent dye tracer assays. The results showed that tdy2 yellow leaf regions were defective in phloem export but competent in long-distance transport. Furthermore, transmission electron microscopy of tdy2 yellow leaf regions showed incomplete vascular differentiation and implicated a defect in cell-to-cell solute movement between phloem companion cells and sieve elements. The disruption of sucrose movement in the phloem in tdy2 mutants provides evidence that the Tdy2 callose synthase functions in vascular maturation and that the vascular defects result in impaired symplastic trafficking into the phloem translocation stream. PMID:22932757

  15. Silencing of OPR3 in tomato reveals the role of OPDA in callose deposition during the activation of defense responses against Botrytis cinerea.

    PubMed

    Scalschi, Loredana; Sanmartín, Maite; Camañes, Gemma; Troncho, Pilar; Sánchez-Serrano, José J; García-Agustín, Pilar; Vicedo, Begonya

    2015-01-01

    Cis-(+)-12-oxo-phytodienoic acid (OPDA) is likely to play signaling roles in plant defense that do not depend on its further conversion to the phytohormone jasmonic acid. To elucidate the role of OPDA in Solanum lycopersicum (tomato) plant defense, we have silenced the 12-oxophytodienoate reductase 3 (OPR3) gene. Two independent transgenic tomato lines (SiOPR3-1 and SiOPR3-2) showed significantly reduced OPR3 expression upon infection with the necrotrophic pathogen Botrytis cinerea. Moreover, SiOPR3 plants are more susceptible to this pathogen, and this susceptibility is accompanied by a significant decrease in OPDA levels and by the production of JA-Ile being almost abolished. OPR3 silencing also leads to a major reduction in the expression of other genes of the jasmonic acid (JA) synthesis and signaling pathways after infection. These results confirm that in tomato plants, as in Arabidopsis, OPR3 determines OPDA availability for JA biosynthesis. In addition, we show that an intact JA biosynthetic pathway is required for proper callose deposition, as its pathogen-induced accumulation is reduced in SiOPR3 plants. Interestingly, OPDA, but not JA, treatment restored basal resistance to B. cinerea and induced callose deposition in SiOPR3-1 and SiOPR3-2 transgenic plants. These results provide clear evidence that OPDA by itself plays a major role in the basal defense of tomato plants against this necrotrophic pathogen.

  16. Connected Learning.

    ERIC Educational Resources Information Center

    Brown, David E.

    2000-01-01

    California has numerous niche programs stressing both academic rigor and career connections. These occur most successfully where business and elected officials support K-12 partnerships and provide job-shadowing opportunities, internships, and classroom instruction offered by business partners. A sidebar outlines school-to-work principles. (MLH)

  17. Connection, 1995.

    ERIC Educational Resources Information Center

    Lalley, Jacqueline, Ed.

    1995-01-01

    This document consists or the six issues of the Family Resource Coalition's newsletter "Connection" published in 1995. These newsletter issues explore matters pertaining to family support and related programs. Featured articles are as follows: (January-February) "Board Approves Long-Range Plan, Reaffirms FRC's [Family Resource…

  18. Learning Connections

    ERIC Educational Resources Information Center

    Royer, Regina D.; Richards, Patricia O.

    2005-01-01

    In this edition of Learning Connections, the authors show how technology can enhance study of weather patterns, reading comprehension, real-world training, critical thinking, health education, and art criticism. The following sections are included: (1) Social Studies; (2) Language Arts; (3) Computer Science and ICT; (4) Art; and (5) Health.…

  19. 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.

  20. 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…

  1. 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…

  2. Resting Afferent Renal Nerve Discharge and Renal Inflammation: Elucidating the Role of Afferent and Efferent Renal Nerves in Deoxycorticosterone Acetate Salt Hypertension.

    PubMed

    Banek, Christopher T; Knuepfer, Mark M; Foss, Jason D; Fiege, Jessica K; Asirvatham-Jeyaraj, Ninitha; Van Helden, Dusty; Shimizu, Yoji; Osborn, John W

    2016-12-01

    Renal sympathetic denervation (RDNx) has emerged as a novel therapy for hypertension; however, the therapeutic mechanisms remain unclear. Efferent renal sympathetic nerve activity has recently been implicated in trafficking renal inflammatory immune cells and inflammatory chemokine and cytokine release. Several of these inflammatory mediators are known to activate or sensitize afferent nerves. This study aimed to elucidate the roles of efferent and afferent renal nerves in renal inflammation and hypertension in the deoxycorticosterone acetate (DOCA) salt rat model. Uninephrectomized male Sprague-Dawley rats (275-300 g) underwent afferent-selective RDNx (n=10), total RDNx (n=10), or Sham (n=10) and were instrumented for the measurement of mean arterial pressure and heart rate by radiotelemetry. Rats received 100-mg DOCA (SC) and 0.9% saline for 21 days. Resting afferent renal nerve activity in DOCA and vehicle animals was measured after the treatment protocol. Renal tissue inflammation was assessed by renal cytokine content and T-cell infiltration and activation. Resting afferent renal nerve activity, expressed as a percent of peak afferent nerve activity, was substantially increased in DOCA than in vehicle (35.8±4.4 versus 15.3±2.8 %Amax). The DOCA-Sham hypertension (132±12 mm Hg) was attenuated by ≈50% in both total RDNx (111±8 mm Hg) and afferent-selective RDNx (117±5 mm Hg) groups. Renal inflammation induced by DOCA salt was attenuated by total RDNx and unaffected by afferent-selective RDNx. These data suggest that afferent renal nerve activity may mediate the hypertensive response to DOCA salt, but inflammation may be mediated primarily by efferent renal sympathetic nerve activity. Also, resting afferent renal nerve activity is elevated in DOCA salt rats, which may highlight a crucial neural mechanism in the development and maintenance of hypertension. © 2016 American Heart Association, Inc.

  3. Lateral hypothalamic area stimulation excites neurons in the region of the subfornical organ with efferent projections to the hypothalamic paraventricular nucleus in the rat.

    PubMed

    Tanaka, J; Kaba, H; Saito, H; Seto, K

    1986-07-30

    Fifteen neurons in the region of the subfornical organ (SFO) were antidromically activated by electrical stimulation of the paraventricular nucleus (PVN) in the rat. Electrical stimulation of the lateral hypothalamic area (LHA) excited the activity of 9 of the identified units, but did not affect the remaining units. The excitatory response of the identified units was blocked by microiontophoretically (MIPh) applied saralasin (Sar), an angiotensin II (ANGII) antagonist, but not by atropine (Atr), a muscarinic antagonist. These results suggest that the LHA has an excitatory influence on the activity of neurons in the region of the SFO with efferent projections to the PVN and that the influence may be mediated by ANGII receptors.

  4. Magnetic Connections

    NASA Image and Video Library

    2017-09-28

    A series of linked loops across the face of the Sun highlighted the dynamic magnetic connections generated by several active regions (Jan. 3-6, 2015). Active regions have magnetic north and south polarity and the arcing loops find the opposite pole to make the connection. What is unusual here is that they all kind of line up and link nicely together. These movies are made in a wavelength of extreme ultraviolet light. Credit: NASA/Solar Dynamics Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  5. Role of NMDA receptors in the lateralized potentiation of amygdala afferent and efferent neural transmission produced by predator stress.

    PubMed

    Adamec, Robert; Blundell, Jacqueline; Burton, Paul

    2005-09-15

    The present study investigated the role of NMDA receptors in behavioral and neuroplastic changes in amygdala efferent (central amygdala to periaqueductal gray-ACE-PAG) and amygdala afferent (ventral angular bundle to basolateral amygdala-VAB-BLA) pathways in response to predator stress. Effects on brain and behavioral response to predator stress of competitive block of NMDA receptors with a dose of 10 mg/kg of CPP (3-(2-carboxypiperazin4-yl)propyl-l-phosphonic acid) were studied. Behavioral response to stress was tested with hole board, elevated plus maze, light/dark box, social interaction and acoustic startle tests. CPP was administered i.p. 30 min prior to predator stress and blocked the effects of predator on some but not all behaviors measured 8-9 days later. Effects of predator stress and CPP on potentials evoked in the PAG by single pulse stimulation of the ACE and in the BLA by single pulse stimulation of VAB were assessed 10-11 days after predator stress. Predator stress potentiated ACE-PAG evoked potentials in the right but not the left hemisphere, replicating previous work. Predator stress potentiated VAB-BLA transmission in both hemispheres 10-11 days after predator stress. Right hemisphere VAB-BLA potentiation replicated and extended past studies showing right hemisphere potentiation at 1 and 9 days after stress. Left VAB-BLA potentiation effects differed from the long term depression seen in VAB-BLA at 1 and 9 days after stress in previous studies. CPP blocked predator stress-induced potentiation of ACE-PAG and VAB-BLA evoked potentials in the right hemisphere. CPP did not block left VAB-BLA potentiation, rather CPP amplified it. Left hemisphere effects of CPP were interpreted as reflecting block of NMDA dependent long term depression, which unmasked a non-NMDA dependent potentiation. Taken together, the findings add to a body of evidence suggesting that a syndrome of behavioral changes follows predator stress. Components of this syndrome likely

  6. 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.

  7. The accessory optic system: basic organization with an update on connectivity, neurochemistry, and function.

    PubMed

    Giolli, Roland A; Blanks, Robert H I; Lui, Fausta

    2006-01-01

    The accessory optic system (AOS) is formed by a series of terminal nuclei receiving direct visual information from the retina via one or more accessory optic tracts. In addition to the retinal input, derived from ganglion cells that characteristically have large receptive fields, are direction-selective, and have a preference for slow moving stimuli, there are now well-characterized afferent connections with a key pretectal nucleus (nucleus of the optic tract) and the ventral lateral geniculate nucleus. The efferent connections of the AOS are robust, targeting brainstem and other structures in support of visual-oculomotor events such as optokinetic nystagmus and visual-vestibular interaction. This chapter reviews the newer experimental findings while including older data concerning the structural and functional organization of the AOS. We then consider the ontogeny and phylogeny of the AOS and include a discussion of similarities and differences in the anatomical organization of the AOS in nonmammalian and mammalian species. This is followed by sections dealing with retinal and cerebral cortical afferents to the AOS nuclei, interneuronal connections of AOS neurons, and the efferents of the AOS nuclei. We conclude with a section on Functional Considerations dealing with the issues of the response properties of AOS neurons, lesion and metabolic studies, and the AOS and spatial cognition.

  8. Effective cerebral connectivity during silent speech reading revealed by functional magnetic resonance imaging.

    PubMed

    Chu, Ying-Hua; Lin, Fa-Hsuan; Chou, Yu-Jen; Tsai, Kevin W-K; Kuo, Wen-Jui; Jääskeläinen, Iiro P

    2013-01-01

    Seeing the articulatory gestures of the speaker ("speech reading") enhances speech perception especially in noisy conditions. Recent neuroimaging studies tentatively suggest that speech reading activates speech motor system, which then influences superior-posterior temporal lobe auditory areas via an efference copy. Here, nineteen healthy volunteers were presented with silent videoclips of a person articulating Finnish vowels /a/, /i/ (non-targets), and /o/ (targets) during event-related functional magnetic resonance imaging (fMRI). Speech reading significantly activated visual cortex, posterior fusiform gyrus (pFG), posterior superior temporal gyrus and sulcus (pSTG/S), and the speech motor areas, including premotor cortex, parts of the inferior (IFG) and middle (MFG) frontal gyri extending into frontal polar (FP) structures, somatosensory areas, and supramarginal gyrus (SMG). Structural equation modelling (SEM) of these data suggested that information flows first from extrastriate visual cortex to pFS, and from there, in parallel, to pSTG/S and MFG/FP. From pSTG/S information flow continues to IFG or SMG and eventually somatosensory areas. Feedback connectivity was estimated to run from MFG/FP to IFG, and pSTG/S. The direct functional connection from pFG to MFG/FP and feedback connection from MFG/FP to pSTG/S and IFG support the hypothesis of prefrontal speech motor areas influencing auditory speech processing in pSTG/S via an efference copy.

  9. Callosities, corns, and calluses.

    PubMed

    Singh, D; Bentley, G; Trevino, S G

    1996-06-01

    Inappropriate shoes, abnormal foot mechanics, and high levels of activity produce pressure and friction that lead to corns and calluses. Most lesions can be managed conservatively by proper footwear, orthoses, and, if necessary, regular paring. The lesions usually disappear when the causative mechanical forces are removed. Surgery is rarely indicated and should be specifically aimed at correcting the abnormal mechanical stresses.

  10. Callosities, corns, and calluses.

    PubMed Central

    Singh, D.; Bentley, G.; Trevino, S. G.

    1996-01-01

    Inappropriate shoes, abnormal foot mechanics, and high levels of activity produce pressure and friction that lead to corns and calluses. Most lesions can be managed conservatively by proper footwear, orthoses, and, if necessary, regular paring. The lesions usually disappear when the causative mechanical forces are removed. Surgery is rarely indicated and should be specifically aimed at correcting the abnormal mechanical stresses. Images Fig 2 Fig 3 Fig 4 Fig 6 Fig 7 PMID:8646101

  11. 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

  12. The alpha9/alpha10-containing nicotinic ACh receptor is directly modulated by opioid peptides, endomorphin-1, and dynorphin B, proposed efferent cotransmitters in the inner ear.

    PubMed

    Lioudyno, M I; Verbitsky, M; Glowatzki, E; Holt, J C; Boulter, J; Zadina, J E; Elgoyhen, A B; Guth, P S

    2002-08-01

    Opioid peptides have been detected in the auditory and vestibular efferent neurons where they colocalize with the major neurotransmitter, acetylcholine. We investigated the function of opioids to modulate neurotransmission mediated by hair cell's alpha9/alpha10-containing nicotinic acetylcholine receptors (alpha9/alpha10nAChRs). The endogenous opioid peptides, endomorphin-1 (mu agonist) and dynorphin B (kappa agonist), but not a delta agonist [D-Pen2,D-Pen-5]enkephalin, inhibited the acetylcholine-evoked currents in frog saccular hair cells and rat inner hair cells. This inhibition was noncompetitive, voltage-independent, and was accompanied by an acceleration of the rate of current decay. Selective mu- and kappa-opioid receptor antagonists did not block the inhibition, although partial reduction by naloxone was observed. All opioid antagonists tested also reduced the acetylcholine response. Endomorphin-1 and dynorphin B inhibited the acetylcholine-evoked currents in alpha9/alpha10-expressing Xenopus oocytes. Because oocytes lack opioid receptors, it provides strong evidence for the direct interaction of opioid peptides with alpha9/alpha10nAChR. alpha9/alpha10nAChR is a target for modulation by endomorphin-1 and dynorphin B, efferent cotransmitters in the inner ear.

  13. 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.

  14. 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.

  15. 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

  16. Iodinated contrast media differentially affect afferent and efferent arteriolar tone and reactivity in mice: a possible explanation for reduced glomerular filtration rate.

    PubMed

    Liu, Zhi Z; Viegas, Vinicius U; Perlewitz, Andrea; Lai, En Y; Persson, Pontus B; Patzak, Andreas; Sendeski, Mauricio M

    2012-12-01

    To determine the effect of the iodinated contrast medium iodixanol on arteriolar tone in afferent and efferent arterioles of the glomerulus and the functional interactions with the major modulators of arteriolar tone, angiotensin II and nitric oxide, in mice. Animal handling conformed to the ethics guidelines of the Office for Health and Social Matters of Berlin. Arterioles were isolated from 136 C57BL/6 mice, perfused with either vehicle solution or iodixanol (23 mg of iodine per milliliter) for 20 minutes, followed by angiotensin II administration. Fluorescence of 3-amino-4-(N-methylamino)-2',7'-difluorofluorescein (DAF-FM) and dihydroethidium (DHE) were used for quantification of nitric oxide bioavailability and superoxide concentration, respectively. Statistical analysis of time- and dose-dependent data was performed by using the nonparametric test for repeated measurements. With iodixanol, afferent arteriole diameters were significantly reduced from 9.2 µm to 8.3 µm; in control group, the diameters were increased from 8.7 µm to 9.3 µm (P = .008). Nitric oxide synthase inhibition augmented iodixanol-induced constriction, with diameters reduced from 9.9 µm to 5.8 µm (P < .0001). DAF-FM fluorescence increased less during iodixanol treatment and nitric oxide synthase inhibition (3.6% and 3.7% vs 10.7% in control group, P = .009 and P = .049, respectively), indicating impaired nitric oxide bioavailability. With iodixanol, DHE fluorescence ratio was increased by 12% (P < .0001). Angiotensin II responses were enhanced by iodixanol and by nitric oxide synthase inhibition after perfusion with iodixanol (3.3 µm and 4.3 µm vs 7.5 µm [control group] with 1 × 10(-6)/mol/L angiotensin II, P = .03 for both). In contrast, in efferent arterioles, neither their basal diameters nor the responses to angiotensin II were significantly affected by iodixanol. A more pronounced effect of iodixanol on afferent than on efferent arterioles may contribute to the reduction of

  17. Trench connection.

    PubMed

    Jamieson, Alan J; Fujii, Toyonobu

    2011-10-23

    'Trench Connection' was the first international symposium focusing primarily on the hadal zone (depths greater than 6000 m). It was held at the University of Tokyo's Atmosphere and Ocean Research Institute in November 2010. The symposium was successful in having attracted an international collective of scientists and engineers to discuss the latest developments in the exploration and understanding of the deepest environments on Earth. The symposium sessions were categorized into three themes: (i) new deep-submergence technology; (ii) trench ecology and evolution; and (iii) the physical environment. Recent technological developments have overcome the challenges of accessing the extreme depths, which have in turn prompted an international renewed interest in researching physical and biological aspects of the hadal ecosystems. This bringing together of international participants from different disciplines led to healthy discussions throughout the symposium, providing potential opportunities and realizations of where the future of unravelling hadal ecology lies. Hadal science is still at relatively rudimentary levels compared with those of shallower marine environments; however, it became apparent at the symposium that it is now an ever-expanding scientific field.

  18. 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…

  19. 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…

  20. 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.

  1. 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.

  2. 78 FR 55684 - ConnectED Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-11

    ... ConnectED Workshop will discuss the growing bandwidth needs of K-12 schools as more schools use mobile devices to enrich the learning experience; as teachers increasingly integrate Web video and other digital...

  3. 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

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

    2006-10-06

    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. 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-beta-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. 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. Pollen

  4. [Original treatment of constitutional painful callosities by surgical excision, collagen/elastin matrix (MatriDerm(®)) and split thickness skin graft secured by negative wound therapy].

    PubMed

    Atlan, M; Naouri, M; Lorette, G; Estève, E; Zakine, G

    2011-04-01

    Constitutional painful callosities is an unusual pathology, integrated in the frame of "palmoplantar keratodermia" (PPK). Lesions are located at areas of support of the sole. These lesions are painful and disable the normal walking. Treatments are suspensive and painkillers. We report our experience of a single surgical treatment: surgical excision, split thickness skin graft applied on a dermal substitute and secured by negative wound therapy. A 28-year-old patient, affected by this disease, has a desire of pregnancy but her treatment is highly teratogen. A year post-op, wounds were healed. The walk was possible with a relief of the pain, without any ulcerations. The surgical treatment by excision and graft or flaps was previously reported for PPK. The use of dermal substitute was never described for this indication. Dermal substitute compensate the thickness of the soft tissue defect and give an accurate quality of elasticity in this localisation .The negative wound therapy enhances the quality and shortens the length of graft taking, and the adhesion of the dermal substitute on his bed. Copyright © 2009 Elsevier Masson SAS. All rights reserved.

  5. Severe form of radiculo - myelo - neuropathy with meningo - encephalitis secondary to Angiostrongylus cantonensis infection: unusual corpus callosal lesions and serial magnetic resonance imaging findings.

    PubMed

    Nalini, Atchayaram; Ramakrishna, Anil; Dekumoy, Paron; Kumar, Raju Ravi; Pakdee, Wallop; Saini, Jitender; Hegde, Vinay S

    2013-01-01

    A 43-year-old man presented with the symptoms of recurrent lower abdominal pain, malaise and loss of appetite of 3-week duration, followed by acute onset of generalized paresthesias, fever and headache which progressed over few days to quadriparesis, altered sensorium, urinary and fecal incontinence. He had consumed raw tongue, liver, gall bladder and testicles of monitor lizard (Varanus bengalensis). Blood picture showed eosinophilia and cerebrospinal fluid (CSF) analysis revealed elevated protein and eosinophilia. Serum and CSF serology was positive for angiostrongyliasis. Magnetic resonance imaging showed focal hyperintense lesions in the corpus callosum and brainstem and an enhancing lesion in the cerebellum. Post-contrast T1-weighted axial images of spine showed evidence of cervical cord hyperintense lesions and root enhancement. Susceptibility weighted images/phase images showed unusual feature of multiple hemorrhagic lesions in the posterior fossa and supratentorial areas. Diffusion showed no restriction of corpus callosal lesions. Patient was treated with the high dose parenteral steroids with albendazole and at 6-month follow-up and had a remarkable recovery.

  6. 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.

  7. 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 ...

  8. 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 ...

  9. DISSECTING HABITAT CONNECTIVITY

    EPA Science Inventory

    abstract

    Connectivity is increasingly recognized as an important element of a successful reserve design. Connectivity matters in reserve design to the extent that it promotes or hinders the viability of target populations. While conceptually straightforward, connectivity i...

  10. DISSECTING HABITAT CONNECTIVITY

    EPA Science Inventory

    abstract

    Connectivity is increasingly recognized as an important element of a successful reserve design. Connectivity matters in reserve design to the extent that it promotes or hinders the viability of target populations. While conceptually straightforward, connectivity i...

  11. Functioning of Circuits Connecting Thalamus and Cortex.

    PubMed

    Sherman, S Murray

    2017-03-16

    Glutamatergic pathways in thalamus and cortex are divided into two distinct classes: driver, which carries the main information between cells, and modulator, which modifies how driver inputs function. Identifying driver inputs helps to reveal functional computational circuits, and one set of such circuits identified by this approach are cortico-thalamo-cortical (or transthalamic corticocortical) circuits. This, in turn, leads to the conclusion that there are two types of thalamic relay: first order nuclei (such as the lateral geniculate nucleus) that relay driver input from a subcortical source (i.e., retina), and higher order nuclei (such as the pulvinar) which are involved in these transthalamic pathways by relaying driver input from layer 5 of one cortical area to another. This thalamic division is also seen in other sensory pathways and beyond these so that most of thalamus by volume consists of higher-order relays. Many, and perhaps all, direct driver connections between cortical areas are paralleled by an indirect cortico-thalamo-cortical (transthalamic) driver route involving higher order thalamic relays. Such thalamic relays represent a heretofore unappreciated role in cortical functioning, and this assessment challenges and extends conventional views regarding both the role of thalamus and mechanisms of corticocortical communication. Finally, many and perhaps the vast majority of driver inputs relayed through thalamus arrive via branching axons, with extrathalamic targets often being subcortical motor centers. This raises the possibility that inputs relayed by thalamus to cortex also serve as efference copies, and this may represent an important feature of information relayed up the cortical hierarchy via transthalamic circuits. © 2017 American Physiological Society. Compr Physiol 7:713-739, 2017.

  12. 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.

  13. 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.

  14. The Cortical Connectivity of the Prefrontal Cortex in the Monkey Brain

    PubMed Central

    Yeterian, Edward H.; Pandya, Deepak N.; Tomaiuolo, Francesco; Petrides, Michael

    2011-01-01

    One dimension of understanding the functions of the prefrontal cortex is knowledge of cortical connectivity. We have surveyed three aspects of prefrontal cortical connections: local projections (within the frontal lobe), the termination patterns of long association (post-Rolandic) projections, and the trajectories of major fiber pathways. The local connections appear to be organized in relation to dorsal (hippocampal origin) and ventral (paleocortical origin) architectonic trends. According to the proposal of a dual origin of the cerebral cortex, cortical areas can be traced as originating from archicortex (hippocampus) on the one hand, and paleocortex, on the other hand, in a stepwise manner (e.g., Sanides, 1969; Pandya and Yeterian, 1985). Prefrontal areas within each trend are connected with less architectonically differentiated areas, and, on the other hand, with more differentiated areas. Such organization may allow for the systematic exchange of information within each architectonic trend. The long connections of the prefrontal cortex with post-Rolandic regions seem to be organized preferentially in relation to dorsal and ventral prefrontal architectonic trends. Prefrontal areas are connected with post-Rolandic auditory, visual and somatosensory association areas, and with multimodal and paralimbic regions. This long connectivity likely works in conjunction with local connections to serve prefrontal cortical functions. The afferent and efferent connections of the prefrontal cortex with post-Rolandic regions are conveyed by specific long association pathways. These pathways as well appear to be organized in relation to dorsal and ventral prefrontal architectonic trends. Finally, although prefrontal areas have preferential connections in relation to dual architectonic trends, it is clear that there are interconnections between and among areas in each trend, which may provide a substrate for the overall integrative function of the prefrontal cortex. Prefrontal

  15. 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.

  16. Thirsty business: cell, region, and membrane specificity of aquaporins in the testis, efferent ducts, and epididymis and factors regulating their expression.

    PubMed

    Hermo, Louis; Smith, Charles E

    2011-01-01

    Water content within the male reproductive tract is stringently regulated in order to promote sperm differentiation and maturation. Aquaporins (AQP) are a family of integral membrane proteins allowing the transcellular transport of water, gases, urea, glycerol, and ions. Past studies from our lab have revealed the following. In the testis, Sertoli cells express AQP 8, whereas germ cells express AQP 7. In the efferent ducts (ED), AQP 1, 9, and 10 localize to microvilli of nonciliated cells, in addition to a basolateral staining for AQP 1, whereas AQP 1 and 10 localize to ciliated cells. AQP 7 and 11 are expressed in the ED epithelium of young but not adult rats, suggesting suppression of translation as rats age. In the adult epididymis, AQP 1 appears in endothelial cells of vascular channels and myoid cells, whereas AQP 3 delineates basal cells. In principal cells, AQP 9 and 11 appear on microvilli, whereas AQP 7 localizes to lateral then to basal plasma membranes in a region-specific manner; AQP 7 also associates with myoid cells. AQP 5 is expressed in corpus and cauda regions. Additionally, several AQPs are expressed by some but not all basal (AQP 7, 11), clear (AQP 7, 9), and halo (AQP 7, 11) cells. Regulation studies reveal a role for estrogen, androgens, and lumicrine factors. These findings indicate unique associations of AQPs with specific membrane domains in a cell type- and region-specific manner within the EDs and epididymis, as well as complex regulation patterns of expression.

  17. Restoration of the efferent phase of the sneeze reflex after regression of an Arnold-Chiari malformation with compression of the medulla oblongata.