Structural Comparison of Premotor Neurons in Silkworm Moths

Kanako Nakajima¹*, Soichiro Morishita², Hajime Asama², Tomoki Kazawa³, Ryohei Kanzaki³ and Taketoshi Mishima⁴

¹Fujita Corporation, 4-25-2 Sendagaya, Shibuya-ku, Tokyo 151-8570, Japan
²RACE, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8568, Japan
³RCAST, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
⁴Saitama University, 255 Shimo-okubo, Sakura, Saitama, Saitama 338-8570, Japan
*E-mail address: kanako.nakajima@fujita.co.jp

(Received July 25, 2009; Accepted September 12, 2009)

Abstract. In most cases, differences in neuronal function depend on the neuronal structure, and it is thought that shape and structure are closely connected. However, a relationship between neuronal shape and function is not elucidated because there are no elucidation methods beyond a visual comparison. This paper objectively compares the neuronal structure with several structural features which are extracted from the three-dimensional form of a silkworm moth's neuron. These features are based on biologist's knowledge in morphology of a silkworm moth's neuron; a second-order moment represents the positional relation of nerve fibers, and eigenvalues of variancecovariance matrix of coordinate values of nerve fibers represent a spatial extent of nerve fibers. In the result, objectively structural dissimilarity and similarity between neurons are found; ambiguous evaluation criterions of biologists are quantified. In addition, structural features which are strongly associated with the function of premotor neurons are found.

Keywords: Objective Comparison, Structural Analysis, Three-Dimensional Form, Premotor Neuron