660 resultados para Asia--Maps.
Resumo:
Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
Resumo:
Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
Resumo:
This article is an edited transcription of a virtual symposium promoted by the Brazilian Society of Neuroscience and Behavior (SBNeC). Although the dynamics of sensory and motor representations have been one of the most studied features of the central nervous system, the actual mechanisms of brain plasticity that underlie the dynamic nature of sensory and motor maps are not entirely unraveled. Our discussion began with the notion that the processing of sensory information depends on many different cortical areas. Some of them are arranged topographically and others have non-topographic (analytical) properties. Besides a sensory component, every cortical area has an efferent output that can be mapped and can influence motor behavior. Although new behaviors might be related to modifications of the sensory or motor representations in a given cortical area, they can also be the result of the acquired ability to make new associations between specific sensory cues and certain movements, a type of learning known as conditioning motor learning. Many types of learning are directly related to the emotional or cognitive context in which a new behavior is acquired. This has been demonstrated by paradigms in which the receptive field properties of cortical neurons are modified when an animal is engaged in a given discrimination task or when a triggering feature is paired with an aversive stimulus. The role of the cholinergic input from the nucleus basalis to the neocortex was also highlighted as one important component of the circuits responsible for the context-dependent changes that can be induced in cortical maps.
Resumo:
In this paper, the topology of cortical visuotopic maps in adult primates is reviewed, with emphasis on recent studies. The observed visuotopic organisation can be summarised with reference to two basic rules. First, adjacent radial columns in the cortex represent partially overlapping regions of the visual field, irrespective of whether these columns are part of the same or different cortical areas. This primary rule is seldom, if ever, violated. Second, adjacent regions of the visual field tend to be represented in adjacent radial columns of a same area. This rule is not as rigid as the first, as many cortical areas form discontinuous, second-order representations of the visual field. A developmental model based on these physiological observations, and on comparative studies of cortical organisation, is then proposed, in order to explain how a combination of molecular specification steps and activity-driven processes can generate the variety of visuotopic organisations observed in adult cortex.
Resumo:
Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
Resumo:
Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
Resumo:
The spinal muscular atrophies (SMA) or hereditary motor neuronopathies result from the continuous degeneration and death of spinal cord lower motor neurons, leading to progressive muscular weakness and atrophy. We describe a large Brazilian family exhibiting an extremely rare, late-onset, dominant, proximal, and progressive SMA accompanied by very unusual manifestations, such as an abnormal sweating pattern, and gastrointestinal and sexual dysfunctions, suggesting concomitant involvement of the autonomic nervous system. We propose a new disease category for this disorder, `hereditary motor and autonomic neuronopathy', and attribute the term, `survival of motor and autonomic neurons 1' (SMAN1) to the respective locus that was mapped to a 14.5 cM region on chromosome 20q13.2-13.3 by genetic linkage analysis and haplotype studies using microsatellite polymorphic markers. This locus lies between markers D20S120 and D20S173 showing a maximum LOD score of 4.6 at D20S171, defining a region with 33 known genes, including several potential candidates. Identifying the SMAN1 gene should not only improve our understanding of the molecular mechanisms underlying lower motor neuron diseases but also help to clarify the relationship between motor and autonomic neurons.
Resumo:
Teoksessa A complete system of geography / E. Bowen, (London) 1747. Plate n:o 25.
Resumo:
Vapaakappalekartuntaan perustuva tilasto Suomessa kustannetuista karttajulkaisuista vuodesta 1991 lähtien
Resumo:
A photograph from the album put together by Wine Advisor Peter J. Morrell with pictures from the Vinexpo Asia-Pacific of 2001. The photograph appears to be of several chefs holding Inniskillin wine with Donald Ziraldo in the centre. The date stamp on the photograph is 4/27/01
Resumo:
The goal of most clustering algorithms is to find the optimal number of clusters (i.e. fewest number of clusters). However, analysis of molecular conformations of biological macromolecules obtained from computer simulations may benefit from a larger array of clusters. The Self-Organizing Map (SOM) clustering method has the advantage of generating large numbers of clusters, but often gives ambiguous results. In this work, SOMs have been shown to be reproducible when the same conformational dataset is independently clustered multiple times (~100), with the help of the Cramérs V-index (C_v). The ability of C_v to determine which SOMs are reproduced is generalizable across different SOM source codes. The conformational ensembles produced from MD (molecular dynamics) and REMD (replica exchange molecular dynamics) simulations of the penta peptide Met-enkephalin (MET) and the 34 amino acid protein human Parathyroid Hormone (hPTH) were used to evaluate SOM reproducibility. The training length for the SOM has a huge impact on the reproducibility. Analysis of MET conformational data definitively determined that toroidal SOMs cluster data better than bordered maps due to the fact that toroidal maps do not have an edge effect. For the source code from MATLAB, it was determined that the learning rate function should be LINEAR with an initial learning rate factor of 0.05 and the SOM should be trained by a sequential algorithm. The trained SOMs can be used as a supervised classification for another dataset. The toroidal 10×10 hexagonal SOMs produced from the MATLAB program for hPTH conformational data produced three sets of reproducible clusters (27%, 15%, and 13% of 100 independent runs) which find similar partitionings to those of smaller 6×6 SOMs. The χ^2 values produced as part of the C_v calculation were used to locate clusters with identical conformational memberships on independently trained SOMs, even those with different dimensions. The χ^2 values could relate the different SOM partitionings to each other.