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Modular Organization (modular + organization)
Selected AbstractsHow does the brain learn language?DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 2 2000Insights from the study of children with, without language impairment Neurobiological studies have generated new ways of thinking about development of brain structure and function. Development involves more than just growth from simple to complex structures. The initial over-abundance of neurons and synaptic connections is subsequently pruned of those that are non-functional. In addition, as behavioural and cognitive functions emerge and become automatized, the underlying brain representations are reorganized. In this paper, I shall argue that these different modes of neurodevelopmental change provide a useful metaphor for examining language acquisition. It will be argued that language acquisition can involve learning to ignore and inhibit irrelevant information, as well as forming new ways of representing complex information economically. Modular organization is not present from the outset, but develops gradually. This analysis suggests a new way of assessing specific language impairment (SLI). There has been much debate as to whether children with SLI lack specific modular components of a language processing system. I propose instead that these children persist in using inefficient ways of representing language. Finally, I consider what we know about the neurobiological basis of such a deficit. There is mounting evidence that children with SLI have subtle structural anomalies affecting the language areas of the brain, which are largely genetically determined. We should not, however, conclude that the language difficulties are immutable. [source] Precise matching of olivo-cortical divergence and cortico-nuclear convergence between somatotopically corresponding areas in the medial C1 and medial C3 zones of the paravermal cerebellumEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2000R. Apps Abstract The paravermal cerebellar cortex contains three spatially separate zones (the C1, C3 and Y zones) which form a functionally coupled system involved in the control of voluntary limb movements. A series of ,modules' has been postulated, each defined by a set of olivary neurons with similar receptive fields, the cortical microzones innervated by these neurons and the group of deep cerebellar nuclear neurons upon which the microzones converge. A key feature of this modular organization is a correspondence between cortical input and output, irrespective of the zonal identity of the microzone. This was tested directly using a combined electrophysiological and bi-directional tracer technique in barbiturate-anaesthetized cats. During an initial operation, small injections of a mix of retrograde and anterograde tracer material (red beads combined with Fluoro-Ruby or green beads combined with biotinylated dextran amine or Fluoro-Emerald) were made into areas of the medial C1 and medial C3 zones in cerebellar lobule V characterized by olivo-cerebellar input from the ventral forelimb. The inferior olive and the deep cerebellar nuclei were then scrutinized for retrogradely labelled cells and anterogradely labelled axon terminals, respectively. For individual experiments, the degree of C1,C3 zone terminal field overlap in the nucleus interpositus anterior was plotted as a function of either the regional overlap of single-labelled cells or the proportion of double-labelled cells in the dorsal accessory olive. The results were highly positively correlated, indicating that cortico-nuclear convergence between parts of the two zones is in close proportion to the corresponding olivo-cerebellar divergence, entirely consistent with the modular hypothesis. [source] Patterning by genetic networksMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 2 2006S. Genieys Abstract We consider here the morphogenesis (pattern formation) problem for some genetic network models. First, we show that any given spatio-temporal pattern can be generated by a genetic network involving a sufficiently large number of genes. Moreover, patterning process can be performed by an effective algorithm. We also show that Turing's or Meinhardt's type reaction,diffusion models can be approximated by genetic networks. These results exploit the fundamental fact that the genes form functional units and are organized in blocks. Due to this modular organization, the genes always are capable to construct any new patterns and even any time sequences of new patterns from old patterns. Computer simulations illustrate some analytical results. Copyright © 2005 John Wiley & Sons, Ltd. [source] Functional analysis of the Alternaria brassicicola non-ribosomal peptide synthetase gene AbNPS2 reveals a role in conidial cell wall constructionMOLECULAR PLANT PATHOLOGY, Issue 1 2007KWANG-HYUNG KIM SUMMARY Alternaria brassicicola is a necrotrophic pathogen causing black spot disease on virtually all cultivated Brassica crops worldwide. In many plant pathosystems fungal secondary metabolites derived from non-ribosomal peptide synthetases (NPSs) are phytotoxic virulence factors or are antibiotics thought to be important for niche competition with other micro-organisms. However, many of the functions of NPS genes and their products are largely unknown. In this study, we investigated the function of one of the A. brassicicola NPS genes, AbNPS2. The predicted amino acid sequence of AbNPS2 showed high sequence similarity with A. brassicae, AbrePsy1, Cochliobolus heterostrophus, NPS4 and a Stagonospora nodorum NPS. The AbNPS2 open reading frame was predicted to be 22 kb in length and encodes a large protein (7195 amino acids) showing typical NPS modular organization. Gene expression analysis of AbNPS2 in wild-type fungus indicated that it is expressed almost exclusively in conidia and conidiophores, broadly in the reproductive developmental phase. AbNPS2 gene disruption mutants showed abnormal spore cell wall morphology and a decreased hydrophobicity phenotype. Conidia of abnps2 mutants displayed an aberrantly inflated cell wall and an increase in lipid bodies compared with wild-type. Further phenotypic analyses of abnps2 mutants showed decreased spore germination rates both in vitro and in vivo, and a marked reduction in sporulation in vivo compared with wild-type fungus. Moreover, virulence tests on Brassicas with abnps2 mutants revealed a significant reduction in lesion size compared with wild-type but only when aged spores were used in experiments. Collectively, these results indicate that AbNPS2 plays an important role in development and virulence. [source] | ||||||||||