Abstract
Reflex activities (M1, M2) of wrist flexor muscles (FCR, FCU) followed by intended movements while catching a falling iron ball were studied. Subjects performed the catching movement following four types of voluntary movement modes; "let go", "holding", "grasping" and "fingering". To eliminate the progressive influence of one mode of experience on reflex activity, a series of trials was set randomly. Surface EMGs were recorded on a data recorder and later those of sixty trials were averaged. The iron ball was released electromagnetically from 45 cm height. Kinetic energy of the falling ball caused the same level of muscle stretch in all four modes. Amplitudes of M1and M2 during "let go" were lower than those during the other three modes. Both FCR and FCU, amplitudes of M1 and M2 showed differences among individuals. It is suggested that the intended conditions or some cortical activations might affect the neural mechanisms with respect to modulation of M1, M2 amplitudes. However, in the present study it was not possible to show a clear difference of M1or M2 between FCR and FCU. Furthermore, we report the influence of the sense of vision on M1and M2 amplitudes. [Jpn J Physiol 54 Suppl:S186 (2004)]
