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Dynamics of excitation patterns is studied in one-dimensional homogeneous lateral-inhibition type neural fields. The existence of a local excitation pattern solution as well as its waveform stability is proved by the use of the Schauder fixed-point theorem and a generalized version of the Perron-Frobenius theorem of positive matrices to the fuction space. The dynamcis of the field is in general multi-stable so that the field can keep short-term memory.

Animal bodies are shaped by skeletons, which are built inside the body by biomineralization of condensed mesenchymal cells in vertebrates [1, 2] and echinoderms [3, 4], or outside the body by apical secretion of extracellular matrices by epidermal cell layers in arthropods [5]. In each case, the skeletons' shapes are a direct reflection of the pattern of skeleton-producing cells [6]. Here we report a newly discovered mode of skeleton formation: assembly of sponges' mineralized skeletal elements (spicules) in locations distant from where they were produced. Although it was known that internal skeletons of sponges consist of spicules assembled into large pole-and-beam structures with a variety of morphologies [7-10], the spicule assembly process (i.e., how spicules become held up and connected basically in staggered tandem) and what types of cells act in this process remained unexplored. Here we found that mature spicules are dynamically transported from where they were produced and then pierce through outer epithelia, and their basal ends become fixed to substrate or connected with such fixed spicules. Newly discovered "transport cells" mediate spicule movement and the "pierce" step, and collagen-secreting basal-epithelial cells fix spicules to the substratum, suggesting that the processes of spiculous skeleton construction are mediated separately by specialized cells. Division of labor by manufacturer, transporter, and cementer cells, and iteration of the sequential mechanical reactions of "transport," "pierce," "raise up," and "cementation," allows construction of the spiculous skeleton spicule by spicule as a self-organized biological structure, with the great plasticity in size and shape required for indeterminate growth, and generating the great morphological diversity of individual sponges.

This new form of myositis must be distinguished from polymyositis and the other conventional forms of myositis. Careful investigation of hidden CAEBV is recommended when patients present with steroid non-responsive chronic progressive generalized myositis, in particular, with lingual or orbital involvement.

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