前庭電気刺激に対する外直筋の反応および眼振との対比につい

抄録

Pulse-train stimulation was given to the horizontal ampullar and to the abducens nerves in cats respectively and each response of the lateral rectus muscle was observed.
In the responses of the lateral rectus muscle induced by stimulation to the horizontal ampullar nerve in awakened stage, isometric mechanogram of tetanic contraction showed an exponential reduction in the rise and the half rise times according to the increase of stimulation-frequency, and showed a convex increase. In anesthetized stage the tetanic contraction showed more prolongation in the rise and the half rise times than in awakened stage and showed a lineal or concave increase on the mechanogram especially wheu stimulation was given under 300 Hz. Concave or convex curves of mechanogram could be clearly formed by means of double pulse-train stimulation at each of the three parts. In the responses of the lateral rectus muscle induced by stimulation to the abducens nerve, the rise time showed little difference from that of ampullar nerve stimulation in awakened stage but the half rise time reduced to 1/2, and all the mechanograms showed a convex increase.
The muscular responses induced by electric stimulation were compared with those of nystagmus in regard to rise time course. The distributions of the rise and the half rise times of tetanic contractions induced by pulse-train stimulation to the horizontal ampullar nerve in anesthetized stage corresponded to u range of the rise time courses in the slow phase of moderate and weak nystagmus, and in awakened stage and in the abducens nerve stimulation corresponded to the range of the slow phase of active nystagmus. The distributions of the rise time courses of tetanic contractions induced by stimulation to the horizontal ampullar nerve in awakened stage and in anesthetized stage corresponded to the range of the fast phase of moderate and weak nystagmus, and the half rise and the rise times of the abducens nerve corresponded to those of the fast phase of active nystagmus.
The mechanisms of muscular activities in the slow and the fast phases of nystagmus were explicated through the phenomena of the rise time courses and the patterns of muscular contractions elicited by electric stimulation to the horizontal ampullar and to the abducens nerves.