Allometric Scaling Laws in the Exploratory Behavior of the Physarum Plasmodium

The plasmodium of Physarum polycephalum is a unicellular and multinuclear giant amoeba. In this paper, the authors investigate four allometric laws in the exploratory behavior of the plasmodium, and integrate them into one schema based on the dynamics of cytoplasmic streaming. This study reveals a novel function of the tubular structure of the plasmodium, shedding new light on the adaptive behavior of the organism. DOI: 10.4018/jalr.2012010103 International Journal of Artificial Life Research, 3(1), 22-33, January-March 2012 23 Copyright © 2012, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. tion route for the contents of cytoplasm and maintain the integrity of the unicellular body. The sheets crawl on plane surfaces searching for food sources, and the cytoplasm serves as a resource for this exploration. The plasmodium shows a variety of locomotive and exploratory patterns according to environmental conditions (Takamatsu, Takaba, & Takizawa, 2009). Recent studies have demonstrated that the plasmodium actually has adaptive capabilities in its exploration. For example, the plasmodium can find a solution to a maze (Nakagaki, Yamada, & Tóth, 2000; Nakagaki, Yamada, & Tóth, 2001; Nakagaki, 2001) and form an optimized network between multiple nodes (Nakagaki, Yamada, & Hara, 2004; Nakagaki, Kobayashi, Nishiura, & Ueda, 2004; Shirakawa & Gunji, 2007). Furthermore, by having such abilities, the plasmodium is also able to solve some graph theoretical problems (Shirakawa, Adamatzky, Gunji, & Miyake, 2009; Shirakawa & Gunji, 2010) and to duplicate the elaborate design of a real railroad network (Tero et al., 2010). The organism is thus attracting a lot of attention, not only from the biological viewpoint, but also in terms of unconventional bio-inspired computing. In fact, some of the researchers in this field insist that the plasmodium can be used as a model of primitive intelligence (Nakagaki, Yamada, & Tóth, 2000). However, all of the computations using the plasmodium listed above are performed after a full search of the problem space. For example, in the formation of an optimized network between multiple food sources (Nakagaki, Yamada, & Hara, 2004; Nakagaki, Kobayashi, Nishiura, & Ueda, 2004; Shirakawa & Gunji, 2007) the plasmodium first covers the whole space of the experimental system, and then forms a network between food sources. There have already been some model studies of the computational activities of the plasmodium, but they also deal only with the behavior of the plasmodium after a full search (Tero et al., 2010; Tero, Kobayashi, & Nakagaki, 2006, 2007; Tero, Tero, Yumiki, Kobayashi, Saigusa, & Nakagaki, 2008). However, there are not many studies on how the plasmodium makes an exploration in Figure 1. The plasmodium of Physarum polycephalum crawling on a 1.5% non-nutrient agar plate. The arrow indicates the sheet-like locomotive front and the arrowhead indicates the tubular structure (Bar: 1 cm). 10 more pages are available in the full version of this document, which may be purchased using the "Add to Cart" button on the product's webpage: www.igi-global.com/article/allometric-scaling-lawsexploratory-behavior/65073?camid=4v1 This title is available in InfoSci-Journals, InfoSci-Journal Disciplines Medicine, Healthcare, and Life Science. Recommend this product to your librarian: www.igi-global.com/e-resources/libraryrecommendation/?id=2