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Peter Thier - One of the best experts on this subject based on the ideXlab platform.
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the role of the monkey dorsal Pontine Nuclei in goal directed eye and hand movements
The Journal of Neuroscience, 2009Co-Authors: Konstantin Tziridis, Peter W Dicke, Peter ThierAbstract:Prevailing concepts on the control of goal-directed hand movements (HM) have focused on a network of cortical areas whose early parieto-occipital stages are thought to extract and integrate information on target and hand location, involving subsequent stages in frontal cortex forming and executing movement plans. The substantial experimental results supporting this “cortical network” concept for hand movements notwithstanding, the concept clearly needs refinement to account for the surprisingly mild HM disturbances resulting from disconnecting the parieto-occipital from the frontal stages of the network. Clinical observations have suggested the cerebropontocerebellar projection as an alternative pathway for the sensory guidance of HM. As a first step in assessing its role, we explored the Pontine Nuclei (PN) of rhesus monkeys, trained to make goal-directed hand and eye movements guided by spatial memory. We were indeed able to delineate a distinct cluster of neurons in the rostrodorsal PN, activated by the preparation and the execution of hand reaches, close to but distinct from the region in which saccade-related neurons may be observed. The movement-related activity of HM-related neurons starts earlier than that of saccade-related neurons and both neuron types are usually effector specific, i.e., they respond only to the movement of the preferred effector. This is also the case when motor synergies involving both effectors are executed. Our findings support the notion of a distinct precerebellar, Pontine visuomotor channel for hand reaches that is anatomically and functionally largely separated from the one serving eye movements.
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the oculomotor role of the Pontine Nuclei and the nucleus reticularis tegmenti pontis
Progress in Brain Research, 2006Co-Authors: Peter Thier, Martin MockAbstract:Abstract Cerebral cortex and the cerebellum interact closely in order to facilitate spatial orientation and the generation of motor behavior, including eye movements. This interaction is based on a massive projection system that allows the exchange of signals between the two cortices. This cerebro-cerebellar communication system includes several intercalated brain stem Nuclei, whose eminent role in the organization of oculomotor behavior has only recently become apparent. This review focuses on the two major Nuclei of this group taking a precerebellar position, the Pontine Nuclei and the nucleus reticularis tegmenti pontis, both intimately involved in the visual guidance of eye movements.
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organization of tectoPontine terminals within the Pontine Nuclei of the rat and their spatial relationship to terminals from the visual and somatosensory cortex
The Journal of Comparative Neurology, 2005Co-Authors: C Schwarz, Martin Mock, Anja Horowski, Peter ThierAbstract:We investigated the spatial relationship of axonal and dendritic structures in the rat Pontine Nuclei (PN), which transfer visual signals from the superior colliculus (SC) and visual cortex (A17) to the cerebellum. Double anterograde tracing (DiI and DiAsp) from different sites in the SC showed that the tectal retinotopy of visual signals is largely lost in the PN. Whereas axon terminals from lateral sites in the SC were confined to a single terminal field close to the cerebral peduncle, medial sites in the SC projected to an additional dorsolateral one. On the other hand, axon terminals originating from the two structures occupy close but, nevertheless, totally nonoverlapping terminal fields within the PN. Furthermore, a quantitative analysis of the dendritic trees of intracellularly filled identified Pontine projection neurons showed that the dendritic fields were confined to either the SC or the A17 terminal fields and never extended into both. We also investigated the projections carrying cortical somatosensory inputs to the PN as these signals are known to converge with tectal ones in the cerebellum. However, terminals originating in the whisker representation of the primary somatosensory cortex and in the SC were located in segregated Pontine compartments as well. Our results, therefore, point to a possible pontocerebellar mapping rule: Functionally related signals, commonly destined for common cerebellar target zones but residing in different afferent locations, may be kept segregated on the level of the PN and converge only later at specific sites in the granular layer of cerebellar cortex. J. Comp. Neurol. 484:283–298, 2005. © 2005 Wiley-Liss, Inc.
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single neuron evidence for a contribution of the dorsal Pontine Nuclei to both types of target directed eye movements saccades and smooth pursuit
European Journal of Neuroscience, 2004Co-Authors: Peter W Dicke, Shabtai Barash, Peter ThierAbstract:: The primate dorsolateral Pontine nucleus (DLPN) is a key link in a cerebro-cerebellar pathway for smooth pursuit eye movements, a pathway assumed to be anatomically segregated from tegmental circuits subserving saccades. However, the existence of afferents from several cerebrocortical and subcortical centres for saccades suggests that the DLPN and neighbouring parts of the dorsal Pontine Nuclei (DPN) might contribute to saccades as well. In order to test this hypothesis, we recorded from the DPN of two monkeys trained to perform smooth pursuit eye movements as well as visually and memory-guided saccades. Out of 281 neurons isolated from the DPN, 138 were responsive in oculomotor tasks. Forty-five were exclusively activated in saccade paradigms, 68 exclusively by smooth pursuit and 25 neurons showed responses in both. Pursuit-related responses reflected sensitivity to eye position, velocity or combinations of velocity and position with minor contributions of acceleration in many cases. When tested in the memory-guided saccades paradigm, 65 out of 70 neurons activated in saccade paradigms showed significant saccade-related bursts and 20 significant activity in the memory period. Our finding of saccade-related activity in the DPN in conjunction with the existence of strong anatomical input from saccade-related cerebrocortical areas suggests that the DPN serves as a precerebellar relay for both pursuit and saccade-related information originating from cerebral cortex, in addition to the classical tecto-tegmental circuitry for saccades.
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binding of signals relevant for action towards a hypothesis of the functional role of the Pontine Nuclei
Trends in Neurosciences, 1999Co-Authors: C Schwarz, Peter ThierAbstract:If numbers matter, the projection that connects the cerebral cortex to the cerebellum is probably one of the most-important pathways through the CNS. Its extensive development as one ascends the phylogenetic scale parallels that of the cerebral hemispheres and the cerebellum, and it accompanies improvements in motor skills, suggesting that this system might have a decisive role in the generation of skilled movement. This article focuses on the Pontine Nuclei (PN), which are intercalated in the cerebro–cerebellar pathway, a large nuclear complex in the ventral brainstem of mammals, whose raison d'etre has as yet not been examined. By considering recent morphological and electrophysiological findings, this article argues that the PN are an interface that is needed to accommodate the grossly different computational principles governing the cerebral cortex and the cerebellum.
Jan G. Bjaalie - One of the best experts on this subject based on the ideXlab platform.
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Branching of individual somatosensory cerebroPontine axons in rat: Evidence of divergence
Brain Structure and Function, 2007Co-Authors: Ingeborg Bolstad, Trygve B. Leergaard, Jan G. BjaalieAbstract:The cerebral cortex conveys major input to the granule cell layer of the cerebellar hemispheres by way of the Pontine Nuclei. Cerebrocortical projections terminate in multiple, widely distributed clusters in the Pontine Nuclei. This clustered organization is thought to provide the transition between the different organizational principles of the cerebrum and cerebellum, and indicates that parallel processing occurs at multiple sites in the Pontine Nuclei. At a cellular level, however, it is unknown whether individual cerebroPontine neurons target pontocerebellar cells located in different clusters or not. We have employed anterograde axonal tracing and 3D computerized reconstruction techniques to characterize the branching pattern and morphology of individual cerebroPontine axons from the primary somatosensory cortex (SI). Our findings show that 43% of the cerebrobulbar fibers arising from SI whisker representations provide two or three fibers entering the Pontine Nuclei, whereas 39% have only one fiber, and the remaining 18% do not project to the Pontine Nuclei. Thus, it appears that a majority of cerebroPontine axons originating in SI whisker representations diverge to contact multiple, separated pontocerebellar cells. Further, 84% of the somatosensory cerebroPontine fibers are collateral branches from cerebrobulbar and/or cerebrospinal parent fibers, while 16% are direct cerebroPontine projections without a further descending projection. A range of thicknesses of the fibers entering the Pontine Nuclei were observed, with collaterals of corticobulbar fibers having the smallest diameter. Taken together, these findings may be related to previously described separate cerebroPontine transmission lines with different properties.
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topographical organization of pathways from somatosensory cortex through the Pontine Nuclei to tactile regions of the rat cerebellar hemispheres
European Journal of Neuroscience, 2006Co-Authors: Trygve B. Leergaard, Sveinung Lillehaug, Erik De Schutter, James M Bower, Jan G. BjaalieAbstract:: The granule cell layer of the cerebellar hemispheres contains a patchy and noncontinuous map of the body surface, consisting of a complex mosaic of multiple perioral tactile representations. Previous physiological studies have shown that cerebrocerebellar mossy fibre projections, conveyed through the Pontine Nuclei, are mapped in registration with peripheral tactile projections to the cerebellum. In contrast to the fractured cerebellar map, the primary somatosensory cortex (SI) is somatotopically organized. To understand better the map transformation occurring in cerebrocerebellar pathways, we injected axonal tracers in electrophysiologically defined locations in Sprague-Dawley rat folium crus IIa, and mapped the distribution of retrogradely labelled neurons within the Pontine Nuclei using three-dimensional (3-D) reconstructions. Tracer injections within the large central upper lip patch in crus IIa-labelled neurons located centrally in the Pontine Nuclei, primarily contralateral to the injected side. Larger injections (covering multiple crus IIa perioral representations) resulted in labelling extending only slightly beyond this region, with a higher density and more ipsilaterally labelled neurons. Combined axonal tracer injections in upper lip representations in SI and crus IIa, revealed a close spatial correspondence between the cerebroPontine terminal fields and the crus IIa projecting neurons. Finally, comparisons with previously published three-dimensional distributions of Pontine neurons labelled following tracer injections in face receiving regions in the paramedian lobule (downloaded from http://www.rbwb.org) revealed similar correspondence. The present data support the coherent topographical organization of cerebro-ponto-cerebellar networks previously suggested from physiological studies. We discuss the present findings in the context of transformations from cerebral somatotopic to cerebellar fractured tactile representations.
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functions of the Pontine Nuclei in cerebro cerebellar communication
Trends in Neurosciences, 2000Co-Authors: Jan G. Bjaalie, Trygve B. LeergaardAbstract:In their article, Schwarz and Thier1xBinding of signals relevant for action: towards a hypothesis of the functional role of the Pontine Nuclei. Schwarz, C. and Thier, P. Trends Neurosci. 1999; 22: 443–451Abstract | Full Text | Full Text PDF | PubMed | Scopus (53)See all References1 review much of the anatomy and physiology of the Pontine Nuclei (PN). Although their paper is highly interesting and emphasizes the possible role of cerebellar feedback projections, we believe there are problems with some of their interpretations. Specifically, they appear to make three assumptions that require further attention: the fractured (discontinuous) mapping of the cortex onto the PN; the segregation of input from different sites in the cortex; and the sharp modular organization in the PN.We suggest that corticoPontine projections are not primarily discontinuous or fractured. In a recent study of corticoPontine development2xTopographical organization in the early postnatal corticoPontine projection: a carbocyanine dye and 3-D computer reconstruction study in the rat. Leergaard, T.B. et al. J. Comp. Neurol. 1995; 361: 77–94Crossref | PubMed | Scopus (33)See all References2, it was reported that: (1) this pathway has a specific projection pattern at early stages of development; (2) there is an orderly topographic relationship between cortex and PN target regions, possibly related to temporal gradients operative within the cortex and PN during development; and (3) the global pattern of corticoPontine projections is continuous. There is an internal-to-external lamellar organization of terminal fields in the PN, with each cortical site contacting primarily one lamellar region of the PN. The initially widespread projections become restricted in adult animals, and the continuous lamellar pattern breaks into pieces, described as patches (or clusters in 3D) within lamellar regions3xCorticoPontine terminal fibres form small scale clusters and large scale lamellae in the cat. Bjaalie, J.G. et al. NeuroReport. 1997>; 8: 1651–1655Crossref | PubMedSee all References, 4xFrom cortical 2-D to brain stem 3-D maps: organization of corticoPontine projections in developing and adult rats. Leergaard, T.B. and Bjaalie, J.G. Soc. Neurosci. Abstr. 1998; 24: 669See all References, 5xThe rat somatosensory cerebro-ponto-cerebellar system: spatial relationships of the SI somatotopic map are preserved in a three-dimensional clustered Pontine map. Leergaard, T.B. et al. J. Comp. Neurol. 2000; PubMedSee all References. These separated patches, observed in single sections from adult animals, might be interpreted as the basis for a fractured map. With computerized 3D reconstructions of complete series of sections, some new neighbouring relationships are observed among patches or clusters of terminal fields in the PN. However, the neighbouring relationships in the PN largely reproduce neighbouring relationships in the cortex, also in adult animals4xFrom cortical 2-D to brain stem 3-D maps: organization of corticoPontine projections in developing and adult rats. Leergaard, T.B. and Bjaalie, J.G. Soc. Neurosci. Abstr. 1998; 24: 669See all References, 5xThe rat somatosensory cerebro-ponto-cerebellar system: spatial relationships of the SI somatotopic map are preserved in a three-dimensional clustered Pontine map. Leergaard, T.B. et al. J. Comp. Neurol. 2000; PubMedSee all References. Thus, Pontine patches or clusters of terminal fields are distributed inside-out to maintain topographic order. Continuous mapping has also been observed on a small scale (tiny injections of two different tracers in adjacent cortical sites; T.B. Leergaard, J.J. Mutic, K.D. Alloway and J.G. Bjaalie, unpublished observations).There is strong evidence for segregated channels through the PN but this does not rule out an integrative role for the PN. On the contrary, overlapping projections have been observed and developmental data suggest that fibres from remote regions of cortex might grow into the same lamellar region of the PN (Ref. 2xTopographical organization in the early postnatal corticoPontine projection: a carbocyanine dye and 3-D computer reconstruction study in the rat. Leergaard, T.B. et al. J. Comp. Neurol. 1995; 361: 77–94Crossref | PubMed | Scopus (33)See all ReferencesRef. 2). This could provide opportunities for some overlapping input to remain in adult animals. There is direct evidence in the cat for overlap of inputs from area 18 and the lateral suprasylvian visual area6xVisual pathways to the cerebellum: segregation in the Pontine Nuclei of terminal fields from different visual cortical areas in the cat. Bjaalie, J.G. and Brodal, P. Neuroscience. 1989; 29: 95–107Crossref | PubMed | Scopus (26)See all References6, and from different sites in the cingulate gyrus7xOrganization of cingulo-ponto-cerebellar connections in the cat. Brodal, P. et al. Anat. Embryol. 1991; 184: 245–254Crossref | PubMed | Scopus (22)See all References7. Other possible combinations of overlapping projections have also been reported (for a review, see Ref. 8xSalient anatomic features of the cortico-ponto-cerebellar pathway. Brodal, P. and Bjaalie, J.G. : 227–249See all ReferencesRef. 8). Furthermore, the enlarged interface between neighbouring clusters, produced by the transformation from a 2D to a 3D map, provides an anatomical basis that could facilitate integration of signals locally in the PN.Schwarz and Thier1xBinding of signals relevant for action: towards a hypothesis of the functional role of the Pontine Nuclei. Schwarz, C. and Thier, P. Trends Neurosci. 1999; 22: 443–451Abstract | Full Text | Full Text PDF | PubMed | Scopus (53)See all References, 9xModular organization of the Pontine Nuclei: dendritic fields of identified Pontine projection neurons in the rat respect the borders of cortical afferent fields. Schwarz, C. and Thier, P. J. Neurosci. 1995; 15: 3475–3489PubMedSee all References argue that dendritic trees of Pontine cells respect the boundaries of terminal fields of axons originating from restricted parts of cortex. The neurons within a terminal field are all thought to share the same input, different from that of neighbouring fields. A major problem with this conclusion is the lack of an operational definition of a Pontine module. As far as we can judge, Schwarz and Thier assume that a corticoPontine terminal field (labelled by an arbitrary cortical injection) corresponds to a Pontine module. How would different sizes of cortical injections affect the size of the module? And how would partially overlapping projections6xVisual pathways to the cerebellum: segregation in the Pontine Nuclei of terminal fields from different visual cortical areas in the cat. Bjaalie, J.G. and Brodal, P. Neuroscience. 1989; 29: 95–107Crossref | PubMed | Scopus (26)See all References, 7xOrganization of cingulo-ponto-cerebellar connections in the cat. Brodal, P. et al. Anat. Embryol. 1991; 184: 245–254Crossref | PubMed | Scopus (22)See all References, 9xModular organization of the Pontine Nuclei: dendritic fields of identified Pontine projection neurons in the rat respect the borders of cortical afferent fields. Schwarz, C. and Thier, P. J. Neurosci. 1995; 15: 3475–3489PubMedSee all References (see also 10xProjections of sensorimotor cortex to the basilar Pontine Nuclei in the rat: an autoradiographic study. Mihailoff, G.A. et al. Brain Res. 1978; 145: 347–354Crossref | PubMed | Scopus (8)See all References, 11xThe projection from the primary motor and somatic sensory cortex to the basilar Pontine Nuclei. A detailed electrophysiological and anatomical study in the rat. Panto, M.R. et al. J. Hirnforsch. 1995; 36: 7–19PubMedSee all References) relate to Pontine modules? Furthermore, synapses on Pontine cells are located mainly on dendrites, with a vast majority on thin dendrites12xElectron-microscopic observations on the structure of the Pontine Nuclei and the mode of termination of the corticoPontine fibres. An experimental study in the cat. Hollander, H. et al. Exp. Brain Res. 1968; 7: 95–110See all References12. Therefore, tips of dendrites extending into adjacent terminal fields could pick up significant amounts of information from outside the module. Further views on this topic are discussed by Brodal and Bjaalie8xSalient anatomic features of the cortico-ponto-cerebellar pathway. Brodal, P. and Bjaalie, J.G. : 227–249See all References8. We find the concept of Pontine modules exciting, but not yet sufficiently explored.In summary, we consider the review by Schwarz and Thier1xBinding of signals relevant for action: towards a hypothesis of the functional role of the Pontine Nuclei. Schwarz, C. and Thier, P. Trends Neurosci. 1999; 22: 443–451Abstract | Full Text | Full Text PDF | PubMed | Scopus (53)See all References1 most useful as a basis for future discussions on the function of the Pontine Nuclei. Their concluding hypothesis, that the PN supports dynamic coupling of cerebellar inputs originating from distant cerebrocortical sites, is, however, problematic. As this hypothesis now stands, it relies on unproven assumptions.
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cat pontocerebellar network numerical capacity and axonal collateral branching of neurones in the Pontine Nuclei projecting to individual parafloccular folia
Neuroscience Research, 1997Co-Authors: Jan G. Bjaalie, Per BrodalAbstract:Abstract We have studied the convergence and divergence in the pontocerebellar pathway. Two or three different fluorescent tracers were injected in separate folia of the parafloccular complex. Retrogradely labelled cells were quantitatively recorded. The estimated total number of labelled neurones in the Pontine Nuclei contralateral to the injection sites was 18 000 (median; range 5000–46 000; 14 cell populations, six animals). Using stereological principles, the total number of neurones on one side in the Pontine Nuclei was estimated to be 490 000 (mean; n =6). Thus, approximately 4% of the total number of neurones in the Pontine Nuclei would project to a single parafloccular folium. Assuming that the highest estimates of labelled cells are the most representative, the proportion would be 9%. Considering that the volume injected makes up a tiny fraction of the total cerebellar cortical volume, these figures reflect an extreme convergence. After injections in adjacent folia we observed 19–27% double labelling. The double labelling frequency dropped steeply with increasing distance between injections. The strong convergence and limited local axonal branching suggest the existence of extensive branching to widely separated cerebellar regions.
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organization of the Pontine Nuclei
Neuroscience Research, 1992Co-Authors: Per Brodal, Jan G. BjaalieAbstract:The Pontine Nuclei provide the cerebellar hemispheres with the majority of their mossy fiber afferents, and receive their main input from the cerebral cortex. Even though the vast majority of Pontine neurons send their axons to the cerebellar cortex, and are contacted monosynaptically by (glutamatergic) corticoPontine fibers, the information-processing taking place is not well understood. In addition to typical projection neurons, the Pontine Nuclei contain putative GABA-ergic interneurons and complex synaptic arrangements. The corticoPontine projection is characterized by a precise but highly divergent terminal pattern. Large and functionally diverse parts of the cerebral cortex contribute; in the monkey the most notable exception is the almost total lack of projections from large parts of the prefrontal and temporal cortices. Within corticoPontine projections from visual and somatosensory areas there is a de-emphasis of central vision and distal parts of the extremities as compared with other connections of these sensory areas. SubcorticoPontine projections provide only a few percent of the total input to the Pontine Nuclei. Certain cell groups, such as the reticular formation, project in a diffuse manner whereas other Nuclei, such as the mammillary nucleus, project to restricted Pontine regions only, partially converging with functionally related corticoPontine connections. The pontocerebellar projection is characterized by a highly convergent pattern, even though there is also marked divergence. Neurons projecting to a single cerebellar folium appear to be confined to a lamella-shaped volume in the Pontine Nuclei. The organization of the Pontine Nuclei suggests that they ensure that information from various, functionally diverse, parts of the cerebral cortex and subcortical Nuclei are brought together and integrated in the cerebellar cortex.
Martin Mock - One of the best experts on this subject based on the ideXlab platform.
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the oculomotor role of the Pontine Nuclei and the nucleus reticularis tegmenti pontis
Progress in Brain Research, 2006Co-Authors: Peter Thier, Martin MockAbstract:Abstract Cerebral cortex and the cerebellum interact closely in order to facilitate spatial orientation and the generation of motor behavior, including eye movements. This interaction is based on a massive projection system that allows the exchange of signals between the two cortices. This cerebro-cerebellar communication system includes several intercalated brain stem Nuclei, whose eminent role in the organization of oculomotor behavior has only recently become apparent. This review focuses on the two major Nuclei of this group taking a precerebellar position, the Pontine Nuclei and the nucleus reticularis tegmenti pontis, both intimately involved in the visual guidance of eye movements.
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organization of tectoPontine terminals within the Pontine Nuclei of the rat and their spatial relationship to terminals from the visual and somatosensory cortex
The Journal of Comparative Neurology, 2005Co-Authors: C Schwarz, Martin Mock, Anja Horowski, Peter ThierAbstract:We investigated the spatial relationship of axonal and dendritic structures in the rat Pontine Nuclei (PN), which transfer visual signals from the superior colliculus (SC) and visual cortex (A17) to the cerebellum. Double anterograde tracing (DiI and DiAsp) from different sites in the SC showed that the tectal retinotopy of visual signals is largely lost in the PN. Whereas axon terminals from lateral sites in the SC were confined to a single terminal field close to the cerebral peduncle, medial sites in the SC projected to an additional dorsolateral one. On the other hand, axon terminals originating from the two structures occupy close but, nevertheless, totally nonoverlapping terminal fields within the PN. Furthermore, a quantitative analysis of the dendritic trees of intracellularly filled identified Pontine projection neurons showed that the dendritic fields were confined to either the SC or the A17 terminal fields and never extended into both. We also investigated the projections carrying cortical somatosensory inputs to the PN as these signals are known to converge with tectal ones in the cerebellum. However, terminals originating in the whisker representation of the primary somatosensory cortex and in the SC were located in segregated Pontine compartments as well. Our results, therefore, point to a possible pontocerebellar mapping rule: Functionally related signals, commonly destined for common cerebellar target zones but residing in different afferent locations, may be kept segregated on the level of the PN and converge only later at specific sites in the granular layer of cerebellar cortex. J. Comp. Neurol. 484:283–298, 2005. © 2005 Wiley-Liss, Inc.
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gabaergic inhibition in the rat Pontine Nuclei is exclusively extrinsic evidence from an in situ hybridization study for gad67 mrna
Experimental Brain Research, 1999Co-Authors: Martin Mock, C Schwarz, Petra Wahle, Peter ThierAbstract:As clearly indicated by our electrophysiological work, GABAergic inhibition plays a powerful role in the Pontine Nuclei (PN), the major link between cerebral cortex and the cerebellum. Using the technique of in situ hybridization for the mRNA encoding for the γ-aminobutyric acid (GABA)-synthesizing isoenzyme glutamic acid decarboxylase67 (GAD67), we demonstrate here the total absence of potentially GABAergic neurons from the rat PN. This negative finding supports the notion that GABAergic inhibition in the PN of rats, unlike that of higher mammals, is exclusively based on extraPontine GABAergic afferents.
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electrophysiological properties of rat Pontine Nuclei neurons in vitro ii postsynaptic potentials
Journal of Neurophysiology, 1997Co-Authors: Martin Mock, C Schwarz, Peter ThierAbstract:Mock, Martin, Cornelius Schwarz, and Peter Thier. Electrophysiological properties of rat Pontine Nuclei neurons in vitro. II. Postsynaptic potentials. J. Neurophysiol. 78: 3338–3350, 1997. We inves...
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electrophysiological properties of rat Pontine Nuclei neurons in vitro i membrane potentials and firing patterns
Journal of Neurophysiology, 1997Co-Authors: C Schwarz, Martin Mock, Peter ThierAbstract:Schwarz, Cornelius, Martin Mock, and Peter Thier. Electrophysiological properties of rat Pontine Nuclei neurons in vitro. I. Membrane potentials and firing patterns. J. Neurophysiol. 78: 3323–3337,...
C Schwarz - One of the best experts on this subject based on the ideXlab platform.
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organization of tectoPontine terminals within the Pontine Nuclei of the rat and their spatial relationship to terminals from the visual and somatosensory cortex
The Journal of Comparative Neurology, 2005Co-Authors: C Schwarz, Martin Mock, Anja Horowski, Peter ThierAbstract:We investigated the spatial relationship of axonal and dendritic structures in the rat Pontine Nuclei (PN), which transfer visual signals from the superior colliculus (SC) and visual cortex (A17) to the cerebellum. Double anterograde tracing (DiI and DiAsp) from different sites in the SC showed that the tectal retinotopy of visual signals is largely lost in the PN. Whereas axon terminals from lateral sites in the SC were confined to a single terminal field close to the cerebral peduncle, medial sites in the SC projected to an additional dorsolateral one. On the other hand, axon terminals originating from the two structures occupy close but, nevertheless, totally nonoverlapping terminal fields within the PN. Furthermore, a quantitative analysis of the dendritic trees of intracellularly filled identified Pontine projection neurons showed that the dendritic fields were confined to either the SC or the A17 terminal fields and never extended into both. We also investigated the projections carrying cortical somatosensory inputs to the PN as these signals are known to converge with tectal ones in the cerebellum. However, terminals originating in the whisker representation of the primary somatosensory cortex and in the SC were located in segregated Pontine compartments as well. Our results, therefore, point to a possible pontocerebellar mapping rule: Functionally related signals, commonly destined for common cerebellar target zones but residing in different afferent locations, may be kept segregated on the level of the PN and converge only later at specific sites in the granular layer of cerebellar cortex. J. Comp. Neurol. 484:283–298, 2005. © 2005 Wiley-Liss, Inc.
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binding of signals relevant for action towards a hypothesis of the functional role of the Pontine Nuclei
Trends in Neurosciences, 1999Co-Authors: C Schwarz, Peter ThierAbstract:If numbers matter, the projection that connects the cerebral cortex to the cerebellum is probably one of the most-important pathways through the CNS. Its extensive development as one ascends the phylogenetic scale parallels that of the cerebral hemispheres and the cerebellum, and it accompanies improvements in motor skills, suggesting that this system might have a decisive role in the generation of skilled movement. This article focuses on the Pontine Nuclei (PN), which are intercalated in the cerebro–cerebellar pathway, a large nuclear complex in the ventral brainstem of mammals, whose raison d'etre has as yet not been examined. By considering recent morphological and electrophysiological findings, this article argues that the PN are an interface that is needed to accommodate the grossly different computational principles governing the cerebral cortex and the cerebellum.
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gabaergic inhibition in the rat Pontine Nuclei is exclusively extrinsic evidence from an in situ hybridization study for gad67 mrna
Experimental Brain Research, 1999Co-Authors: Martin Mock, C Schwarz, Petra Wahle, Peter ThierAbstract:As clearly indicated by our electrophysiological work, GABAergic inhibition plays a powerful role in the Pontine Nuclei (PN), the major link between cerebral cortex and the cerebellum. Using the technique of in situ hybridization for the mRNA encoding for the γ-aminobutyric acid (GABA)-synthesizing isoenzyme glutamic acid decarboxylase67 (GAD67), we demonstrate here the total absence of potentially GABAergic neurons from the rat PN. This negative finding supports the notion that GABAergic inhibition in the PN of rats, unlike that of higher mammals, is exclusively based on extraPontine GABAergic afferents.
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electrophysiological properties of rat Pontine Nuclei neurons in vitro ii postsynaptic potentials
Journal of Neurophysiology, 1997Co-Authors: Martin Mock, C Schwarz, Peter ThierAbstract:Mock, Martin, Cornelius Schwarz, and Peter Thier. Electrophysiological properties of rat Pontine Nuclei neurons in vitro. II. Postsynaptic potentials. J. Neurophysiol. 78: 3338–3350, 1997. We inves...
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electrophysiological properties of rat Pontine Nuclei neurons in vitro i membrane potentials and firing patterns
Journal of Neurophysiology, 1997Co-Authors: C Schwarz, Martin Mock, Peter ThierAbstract:Schwarz, Cornelius, Martin Mock, and Peter Thier. Electrophysiological properties of rat Pontine Nuclei neurons in vitro. I. Membrane potentials and firing patterns. J. Neurophysiol. 78: 3323–3337,...
F Cicirata - One of the best experts on this subject based on the ideXlab platform.
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the basilar Pontine Nuclei and the nucleus reticularis tegmenti pontis subserve distinct cerebrocerebellar pathways
Progress in Brain Research, 2005Co-Authors: F Cicirata, M F Serapide, M R Panto, Rosalba Parenti, Agata Zappala, Annalisa Nicotra, Deborah CiceroAbstract:Abstract Previous studies often considered the basilar Pontine Nuclei (BPN) and the nucleus reticularis tegmenti pontis (NRTP) as relays of a single cerebro-(ponto)-cerebellar pathway. Conversely, the different cortical afferences to the BPN and the NRTP, as well as the anatomical and functional features of the cerebellopetal projections from these Pontine Nuclei, support the different, and for some aspect, complementary arrangement of the cerebrocerebellar pathways relayed by the BPN or NRTP. Both the BPN and the NRTP are innervated from the cerebral cortex, but with regional prevalence. The NRTP is principally innervated from motor or sensori-motor areas while the BPN are principally innervated from sensory, mainly teloceptive, and associative area. Projections from sensory-motor areas were also traced to the BPN. The BPN and NRTP project to all parts of the cerebellar cortex with a similar pattern. In fact, from single areas of them projections were traced to set of sagittal stripes of the cerebellar cortex. In variance to such analogies, the projections to the cerebellar Nuclei differed between those traced from the NRTP and from BPN. In fact, BPN and NRTP have private terminal areas in the cerebellar Nuclei with relatively little overlaps. The BPN innervated the lateroventral part of the nucleus lateralis and the caudoventral aspect of the nucleus interpositalis posterioris. The NRTP principally innervated the mediodorsal part of the nucleus lateralis, the nucleus interpositalis anterioris, the nucleus medialis. Since the single cerebellar Nuclei have their specific targets in the extracerebellar brain areas, it follows that the BPN and the NRTP, passing through their cerebellar Nuclei relays, are devoted to control different brain areas and thus likely to play different functional roles. From single Pontine regions (of both BPN and NRTP) projections were traced to the cerebellar cortex and to the cerebellar Nuclei. In some cases these projections reached areas which are likely anatomically connected (by Purkinje axons). This pattern of the Pontine projections was termed as coupled projection. In some other cases, the projections reached areas of the cerebellar cortex but not the nuclear regions innervated by them. We termed this as uncoupled projection. The existence of both coupled and uncoupled projections, open new vistas on the functional architecture of the pontocerebellar pathway. More in detail, this study showed the different quantitative and topographic distribution of the coupled and uncoupled projections visualized in the cerebellar projections from BPN and NRTP. All these evidences strongly support the anatomical and the functional differences that characterise the cerebrocerebellar pathways relayed by the BPN and the NRTP.
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projections of the basilar Pontine Nuclei and nucleus reticularis tegmenti pontis to the cerebellar Nuclei of the rat
The Journal of Comparative Neurology, 2002Co-Authors: Rosalba Parenti, M F Serapide, M R Panto, Agata Zappala, F CicirataAbstract:This study showed the precise projection pattern of the basilar Pontine Nuclei (BPN) and the nucleus reticularis tegmenti pontis (NRTP) to the cerebellar Nuclei (CN), as well as the different anatomic features of BPN and NRTP projections. The staining of BPN or NRTP with biotinylated dextran labeled projection fibers to complementary topographic areas in the CN. In fact, BPN principally project to a rostrocaudally oriented column of the nucleus lateralis (NL), which at the midcentral level shifts to the lateroventral part of the nucleus, as well as to the caudolateral part of the nucleus interpositus posterioris. The NRTP projects to a rostrocaudal column of the NL, which at the midcentral level shifts medially, as well as to the nucleus interpositalis and to the caudal part of the nucleus medialis. BPN axons in the CN usually branch into short collaterals of simple morphology that involve small terminal areas, whereas NRTP axons branch into longer collaterals of complex morphology involving terminal areas of different sizes. Each site of injection is at the origin of a set of terminal areas in the CN. The set of projections from different BPN or NRTP areas were partially, but never completely, overlapping. Thus, the set of terminal areas in the CN was specific for each area of both BPN and NRTP. Injection of tetramethyl-rhodamine-dextran-amine into the CN stained cell bodies of BPN and NRTP with different repartition on the two sides. The study showed that CN are innervated by the contralateral BPN and not very much by the ipsilateral BPN, whereas they are innervated by NRTP bilaterally, even if with a contralateral prevalence. In conclusion, this study supports the hypothesis that both BPN and NRTP are concerned in the central program for skilled movements, even if they are probably involved in different functional roles. J. Comp. Neurol. 452:115–127, 2002. © 2002 Wiley-Liss, Inc.
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multiple zonal projections of the basilar Pontine Nuclei to the cerebellar cortex of the rat
The Journal of Comparative Neurology, 2001Co-Authors: M F Serapide, M R Panto, Rosalba Parenti, Agata Zappala, F CicirataAbstract:This study revealed a sagittal zonal pattern of projections to the cerebellar cortex after hydraulic or iontophoretic injections of anterograde tracers (tritiated leucine, wheat germ agglutinin-horseradish peroxidase, or biotinylated dextrane amine) in the basilar Pontine Nuclei of Wistar rats. The zonal pattern of projection was observed only after injections of small size, whereas large injections labeled diffusely wide areas of the cerebellar cortex, masking the zonal projection because the fusion of contiguous stripes. Diverging projections to discrete sets of sagittal stripes in the two sides of the cerebellar cortex arose from single injections. The stripes of fiber terminals were sharply delimited on both sides by areas, interstripes, either virtually void of labeling or with a much lower density of labeling. Thus, the areas of the cerebellar cortex were parceled in sets of sagittal compartments, stripes and interstripes, by the Pontine projections. Up to five compartments (three stripes and two interstripes) were observed in the paraflocculus, in the copula pyramidis, and in vermal lobule IX. Up to nine compartments (five stripes and four interstripes) were found in the crus I, the lobulus simplex, the paramedian lobule, and vermal lobules VI‐VIII. Up to seven compartments (four stripes and three interstripes) were found in the crus II. Single injections into the basilar Pontine Nuclei usually labeled symmetric areas of the cerebellar cortex, which, in some cases, showed similar number of stripes. When this was not the case, the stripes were usually more numerous in the contralateral than in the ipsilateral side. All areas of the cerebellar cortex were projected upon, with zonation patterns from different regions of the basilar Pontine Nuclei. The projections of the basilar Pontine Nuclei to the cerebellar cortex were arranged according to a fixed pattern specific for each cortical area, independently of the number of stripes labeled within. The mean width of the stripes visualized in the single cortical areas of different rats was similar, despite the different size of the injections. The length of the stripes ranged widely in the various areas of different rats. The data collected in this study are consistent with the idea that all the mossy afferents to the cerebellar cortex are arranged with a zonal pattern. J. Comp. Neurol. 430:471‐484, 2001. © 2001 Wiley-Liss, Inc. Indexing terms: anterograde tracers; cerebellum; basilar Pontine Nuclei; zonal arrangement
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the projection from the primary motor and somatic sensory cortex to the basilar Pontine Nuclei a detailed electrophysiological and anatomical study in the rat
Journal für Hirnforschung, 1995Co-Authors: M R Panto, P. Angaut, Rosalba Parenti, F Cicirata, F SerapideAbstract:: The projections from the primary motor and somatic sensory cortex onto the basilar Pontine grey were studied in Wistar Rats injecting microvolumes of WGA-HRP solution in sites of the motor and sensory cortex electrophysiologically identified. The main results may be summarized as follows. (a) The projections from both the motor and sensory cortex were found as rostrocaudally oriented columns of terminals in the basilar Pontine Nuclei. The projection from the motor cortex extended to all over the rostrocaudal extension of the basilar Pontine Nuclei. To a rostrocaudal shift of the Pontine projection field correspond a rostrocaudal displacement in the motor area. The projection from the sensory cortex was mainly restricted to the caudal two thirds of the basilar Pontine Nuclei, though the hindlimb region of the sensory cortex also showed a discrete representation in the rostral third of the basilar Pontine Nuclei. (b) The terminal fields of the motor and sensory cortex were segregated except those in the caudal Pontine level, which come from the projection of the hindlimb cortical regions. (c) Within the terminal fields of the projections from the motor as well as from the sensory cortex a clearcut topographical arrangement was observed between the projections of cortical areas controlling the head, the forelimb and the hindlimb regions. (d) Within the location of these major subdivisions, the representations of individual body segments were overlapped for a little part ("convergent zones"), whereas the greater part of their projection zones was selective of each cortical field ("private zones"). In conclusion, the present study showed that the projections from the motor and sensory cortex to the basilar Pontine Nuclei are arranged with a very precise somatotopical organization.
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the pontocerebellar projection longitudinal zonal distribution of fibers from discrete regions of the Pontine Nuclei to vermal and parafloccular cortices in the rat
Brain Research, 1994Co-Authors: M F Serapide, M R Panto, F Cicirata, Constantino Sotelo, Rosalba ParentiAbstract:Abstract A longitudinal parasagittal organization (alternating labeled and unlabeled stripes) of mossy fiber terminals in the paraflocculus and in the vermal lobule VII of the cerebellum was found after small injections (less than 50 nl) of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) into discrete regions of the basilar Pontine Nuclei (BPN) of rats. Up to three stripes were found within the paraflocculus of both sides, following injections (of about 500 μm in diameter) in either the medial or lateral region of the caudal half of the BPN. Up to five stripes were found in the vermal lobule VII after similar size injections into the rostro-ventral region of the BPN. These results emphasize the possibility that the parasagittal zonal arrangement could be a common pattern of organization shared by climbing and mossy fiber afferents.
