1,361 research outputs found
A Note on the Definition and the Development of Cerebellar Purkinje Cell Zones
The definition of Purkinje cell zones by their white matter comprtments, their physiological properties, and their molecular identity and the birthdate of their Purkinje cells will be reviewed
Deitersâ Nucleus. Its Role in Cerebellar Ideogenesis
Otto Deiters (1834â1863) was a promising neuroscientist who, like Ferdinando Rossi, died too young. His notes and drawings were posthumously published by Max Schultze in the book âUntersuchungen ĂŒber Gehirn und RĂŒckenmark.â The book is well-known for his dissections of nerve cells, showing the presence of multiple dendrites and a single axon. Deiters also made beautiful drawings of microscopical sections through the spinal cord and the brain stem, the latter showing the lateral vestibular nucleus which received his name. This nucleus, however, should be considered as a cerebellar nucleus because it receives Purkinje cell axons from the vermal B zone in its dorsal portion. Afferents from the labyrinth occur in its ventral part. The nucleus gives rise to the lateral vestibulospinal tract. The cerebellar B module of which Deitersâ nucleus is the target nucleus was used in many innovative studies of the cerebellum on the zonal organization of the olivocerebellar projection, its somatotopical organization, its microzones, and its role in posture and movement that are the subject of this review
Sponges of the family Esperiopsidae (Demospongiae, Poecilosclerida) from Northwest Africa, with the descriptions of four new species
Sponges belonging to the genera Amphilectus Vosmaer, Esperiopsis Carter and Ulosa de Laubenfels of the family Esperiopsidae were collected during 1986 and 1988 expeditions of the Netherlands Centre for Biodiversity Naturalis (at that time the National Museum of Natural History at Leiden and the Zoological Museum of Amsterdam) in waters off the coasts of Mauritania and the Cape Verde Islands. Four new species, Amphilectus utriculus sp. nov., Amphilectus strepsichelifer sp. nov., Esperiopsis cimensis sp. nov., Ulosa capblancensis sp. nov., and two already known species, Amphilectus cf. fucorum (Esper) and Ulosa stuposa (Esper) are described and discussed
Spin-mediated dissipation and frequency shifts of a cantilever at milliKelvin temperatures
We measure the dissipation and frequency shift of a magnetically coupled
cantilever in the vicinity of a silicon chip, down to mK. The dissipation
and frequency shift originates from the interaction with the unpaired
electrons, associated with the dangling bonds in the native oxide layer of the
silicon, which form a two dimensional system of electron spins. We approach the
sample with a m-diameter magnetic particle attached to an ultrasoft
cantilever, and measure the frequency shift and quality factor as a function of
temperature and the distance. Using a recent theoretical analysis [J. M. de
Voogd et al., arXiv:1508.07972 (2015)] of the dynamics of a system consisting
of a spin and a magnetic resonator, we are able to fit the data and extract the
relaxation time ms and spin density
spins per nm. Our analysis shows that at temperatures mK magnetic
dissipation is an important source of non-contact friction.Comment: 5 pages, 3 figure
Equilibrium spherically curved 2D Lennard-Jones systems
To learn about basic aspects of nano-scale spherical molecular shells during
their formation, spherically curved two-dimensional N-particle Lennard-Jones
systems are simulated, studying curvature evolution paths at zero-temperature.
For many N-values (N<800) equilibrium configurations are traced as a function
of the curvature radius R. Sharp jumps for tiny changes in R between
trajectories with major differences in topological structure correspond to
avalanche-like transitions. For a typical case, N=25, equilibrium
configurations fall on smooth trajectories in state space which can be traced
in the E-R plane. The trajectories show-up with local energy minima, from which
growth in N at steady curvature can develop.Comment: 10 pages, 2 figures, to be published in Journal of Chemical Physic
Cerebellum: What is in a Name? Historical Origins and First Use of This Anatomical Term
In this paper, we study who first used the Latin anatomical term âcerebellumâ for the posterior part of the brain. The suggestion that this term was introduced by Leonardo da Vinci is unlikely. Just before the start of the da Vinci era in the fifteenth century, several authors referred to the cerebellum as âcerebri posteriorus.â Instead, in his translation of Galenâs anatomical text De utilitare particularum of 1307, Nicolo da Reggio used the Latinized Greek word âparencephalon.â More peculiar was the Latin nautical term âpuppi,â referring to the stern of a ship, that was applied to the cerebellum by Constantine the African in his translation of the Arabic Liber regius in the eleventh century. The first to use the term âcerebellumâ appears to be Magnus Hundt in his Anthropologia from 1501. Like many of the anatomists of this period, he was a humanist with an interest in classical literature. They may have encountered the term âcerebellumâ in the writings by classical authors such as Celsus, where it was used as the diminutive of âcerebrumâ for the small brains of small animals, and, subsequently, applied the term to the posterior part of the brain. In the subsequent decades of the sixteenth century, an increasing number of pre-Vesalian authors of anatomical texts started to use the name âcerebellum,â initially often combined with one or more of the earlier terms, but eventually more frequently in isolation. We found that a woodcut in Dryanderâs Anatomia capitis humani of 1536 is the first realistic picture of the cerebellum
Secondary vestibulocerebellar projections to the flocculus and uvulo-nodular lobule of the rabbit: a study using HRP and double fluorescent tracer techniques
The distribution of vestibular neurons projecting to the flocculus and the nodulus and uvula of the caudal vermis (Larsell's lobules X and IX) was investigated with retrograde axonal transport of horseradish peroxidase and the fluorescent tracers Fast Blue, Nuclear Yellow and Diamidino Yellow. The presence of collateral axons innervating the flocculus on one hand and the nodulus and uvula on the other was studied with simultaneous injection of the different fluorescent tracers. The distribution of vestibular neurons projecting to either flocculus or caudal vermis is rather similar and has a bilateral symmetry. The projection from the magnocellular medial vestibular nucleus is very sparse, while that from the lateral vestibular nucleus is absent. The majority of labeled neurons was found in the medial, superior, and descending vestibular nuclei, in that order. Double labeled neurons were distributed in a similar way as the single labeled ones. Labeled neurons project to the nodulus and uvula, the flocculus, and to both parts of the cerebellum simultaneously in a ratio of 12:4:1. Five different populations of vestibulocerebellar neurons can be distinguished on the basis of their projection to the: (1) ipsilateral flocculus, (2) contralateral flocculus, (3) ipsilateral flocculus and nodulus/uvula, (4) contralateral flocculus and nodulus/uvula, and (5) nodulus/uvula
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