The Japanese Journal of Ergonomics
Online ISSN : 1884-2844
Print ISSN : 0549-4974
ISSN-L : 0549-4974
The neurological mechanism on handedness
Y. Kikuchi
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JOURNAL FREE ACCESS

1969 Volume 5 Issue 5 Pages 333-339

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Abstract

This study was designed to investigate the neurological and physiological mechanisms on handedness. From three male students to ten male students of graduate school, Univ. of Tokyo served as subjects of these experiments. Among them there are a few students with left handed. In Figs. 1, 2, we can realize the fact that we perceive the same weight lighter by lifting with dominant hand than with non-dominant. Meanwhile, we can know no differentiation between discharge amounts of both muscles (dominant and non-dominant) used at the case of lifting the same weight in Table 1.
We perceive the same weight heavier by lifting with the muscle fatigued acutely than with the sound muscle (m. biceps brachii of dominant hand) in Fig. 7. There are, however, almost no differentiation between discharge amounts of the same muscle before and after fatigue in Table 2. The τ-s relations given from a single NMU inducing with both mm. flexor digitorum superficialis were indicated in Figs. 8, 9, 10. The subject in Fig. 10 was a left-handed one. In these Figs. 8, 9, 10, we can see that the τ-s relation in handedness has the tendency of spinalization (see Fig. 11). From these results, I can conclude by saying the following.
That is, when we think over the handedness we must take notice of the ratios between cortical factor and spinal factor in impulses coming in the motor (α cell) cell at ventral horn of spinal cord.

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