[Equilibrium of small animals in "drop shaft" experimentation--preliminary study on the frog with vestibular...

We have newly designed instruments for equilibrium experimentation, using a drop shaft, and studied the behavior and EMG Patterns of frogs with or without unilateral vestibular neurectomy, as a preliminary study at JAMIC (Japan Microgravity Center). The results are reported herein and the efficacy of the drop shaft in equilibrium experimentation is also documented. 1) In unilateral vestibular neurectomized frogs, posture--head tilt, leg flexion on the affected side, and leg extension on the opposite side--is maintained and persists under microgravity. Rolling to the affected side was also observed. 2) The latencies of the EMG responses from M. tibialis anticus and M. longissimus dorsi were prolonged on the affected side. 3) The frog is suitable for use in equilibrium experiments utilizing a drop shaft. 4) The JAMIC drop shaft can be used to obtain constant and stable microgravity, 10(-4) G for 10 sec, which is similar to that in space. Drop shafts are suitable for equilibrium experimentation.