1,720,995 research outputs found
Retinal origin of orientation but not direction selective maps in the superior colliculus
No full textThis work was supported by the FWO (G094616N to K.F., G091719N to K.F., and 1205421N to N.K.K.) , the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement nos. 796102 and 894697 to N.K.K. and D.d.M., respectively, and the National Institutes of Health grant 1R01EY032101 (J. Hoy and K.F.) . Thanks to Adrien Philippon for developing the air-cushioned Styrofoam ball setup
Local glycolysis supports injury-induced axonal regeneration
Full text linkL.Masin, S.Bergmans, A.Van Dyck and L.DeGroef were supported by personal fellowships funded by the Research Foundation Flanders (FWO, Belgium) (fellowships 1S42720N, 1165020N,1S94218N, 12I3820N). This research was funded by the FWO (project G082221N) and the KU Leuven Research Council (C14/22/074).Open Access funding provided by KU Leuven Libraries
Reconsidering the Border between the Visual and Posterior Parietal Cortex of Mice
No full textThe posterior parietal cortex (PPC) contributes to multisensory and sensory-motor integration, as well as spatial navigation. Based on primate studies, the PPC is composed of several subdivisions with differing connection patterns, including areas that exhibit retinotopy. In mice the composition of the PPC is still under debate. We propose a revised anatomical delineation in which we classify the higher order visual areas rostrolateral area (RL), anteromedial area (AM), and Medio-Medial-Anterior cortex (MMA) as subregions of the mouse PPC. Retrograde and anterograde tracing revealed connectivity, characteristic for primate PPC, with sensory, retrosplenial, orbitofrontal, cingulate and motor cortex, as well as with several thalamic nuclei and the superior colliculus in the mouse. Regarding cortical input, RL receives major input from the somatosensory barrel field, while AM receives more input from the trunk, whereas MMA receives strong inputs from retrosplenial, cingulate, and orbitofrontal cortices. These input differences suggest that each posterior PPC subregion may have a distinct function. Summarized, we put forward a refined cortical map, including a mouse PPC that contains at least 6 subregions, RL, AM, MMA and PtP, MPta, LPta/A. These anatomical results set the stage for a more detailed understanding about the role that the PPC and its subdivisions play in multisensory integration-based behavior in mice.sponsorship: This work was supported by the KU Leuven Research Council (C14/16/048) and the Research Foundation Flanders (FWO), Belgium via research project funding (G061216N), and a doctoral fellowship to S. R. J. G. (SB/151597). The funding sources had no involvement in study design, collection, analyses and interpretation of the data, or in writing this paper. Wewould like to thank Dr Nathalie Lombaert, Dr Joao Couto, Maroussia Hennes, and Jolien Van Houcke for their helpful comments and suggestions. Conflict of Interest: None declared. (KU Leuven Research Council|C14/16/048, Research Foundation Flanders (FWO), Belgium|G061216N, Research Foundation Flanders (FWO), Belgium|SB/151597)status: Published onlin
Optic nerve injury-induced regeneration in the adult zebrafish is accompanied by spatiotemporal changes in mitochondrial dynamics
Full text linkAxonal regeneration in the central nervous system is an energy-intensive process. In contrast to mammals, adult zebrafish can functionally recover from neuronal injury. This raises the question of how zebrafish can cope with this high energy demand. We previously showed that in adult zebrafish, subjected to an optic nerve crush, an antagonistic axon-dendrite interplay exists wherein the retraction of retinal ganglion cell dendrites is a prerequisite for effective axonal repair. We postulate a 'dendrites for regeneration' paradigm that might be linked to intraneuronal mitochondrial reshuffling, as ganglion cells likely have insufficient resources to maintain dendrites and restore axons simultaneously. Here, we characterized both mitochondrial distribution and mitochondrial dynamics within the different ganglion cell compartments (dendrites, somas, and axons) during the regenerative process. Optic nerve crush resulted in a reduction of mitochondria in the dendrites during dendritic retraction, whereafter enlarged mitochondria appeared in the optic nerve/tract during axonal regrowth. Upon dendritic regrowth in the retina, mitochondrial density inside the retinal dendrites returned to baseline levels. Moreover, a transient increase in mitochondrial fission and biogenesis was observed in retinal ganglion cell somas after optic nerve damage. Taken together, these findings suggest that during optic nerve injury-induced regeneration, mitochondria shift from the dendrites to the axons and back again and that temporary changes in mitochondrial dynamics support axonal and dendritic regrowth after optic nerve crush.sponsorship: This work was financially supported by the Katholieke Universiteit Leuven Research Council (C14/18/053) and the research foundation Flanders (FWO) (G082221N). AB holds a personal L'Oreal/UNESCO (For Women in Science) fellowship. LM, AVD, SB, and SV hold a personal FWO fellowship. (Katholieke Universiteit Leuven Research Council|C14/18/053, research foundation Flanders (FWO)|G082221N, personal L'Oreal/UNESCO (For Women in Science) fellowship, personal FWO fellowship)status: Publishe
Direction Selectivity in the Retina and Beyond
No full textMotion is an essential visual cue used by animals to navigate through their environment, as well as to detect and orientate
correctly toward or away from mates, prey, and predators. In mammals, the processing of motion direction starts at the first stage
of visual processing in the retina. Here, at least seven cell types are dedicated to encoding the direction of motion and carry this
information to central brain areas. The direction-selective circuit in the retina has become a classic model to study how a computation
is implemented in the hardware of the nervous system. Here, we review what the composition of direction-selective
neurons is in the retina, how the direction-selective computation is implemented, and how direction-selective information is
encoded in the response of direction-selective retinal ganglion cells (DSGCs). Finally, we will discuss the role different
direction-selective retinal ganglion cells have in central brain computations and behavior and what their dysfunction tells us
about their role in disease.status: Publishe
A projection specific logic to sampling visual inputs in mouse superior colliculus
Full text linkUsing sensory information to trigger different behaviors relies on circuits that pass through brain regions. The rules by which parallel inputs are routed to downstream targets are poorly understood. The superior colliculus mediates a set of innate behaviors, receiving input from >30 retinal ganglion cell types and projecting to behaviorally important targets including the pulvinar and parabigeminal nucleus. Combining transsynaptic circuit tracing with in vivo and ex vivo electrophysiological recordings, we observed a projection-specific logic where each collicular output pathway sampled a distinct set of retinal inputs. Neurons projecting to the pulvinar or the parabigeminal nucleus showed strongly biased sampling from four cell types each, while six others innervated both pathways. The visual response properties of retinal ganglion cells correlated well with those of their disynaptic targets. These findings open the possibility that projection-specific sampling of retinal inputs forms a basis for the selective triggering of behaviors by the superior colliculus.sponsorship: Fonds Wetenschappelijk Onderzoek G094616N Karl FarrowFP7 People: Marie-Curie Actions 631909 Karl FarrowH2020 Marie Sklodowska-Curie Actions [PEGASUS]2 Marie Sklodowska-Curie Fellowship 12S7917N Katja ReinhardChina Scholarship Council Chen Li (Fonds Wetenschappelijk Onderzoek|G094616N, FP7 People: Marie-Curie Actions|631909, H2020 Marie Sklodowska-Curie Actions|12S7917N, China Scholarship Council)status: Publishe
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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