迷路性，自己受容性直立姿勢制御の検討 フィードバックモデルを用いた分析

Abstract

To clarify the role of vestibular and proprioceptive reflexes in the regulation of the upright standing posture, we analysed with feedback models sways of the head and of the body's center of gravity (BCG) and the activity of the nuchal and soleus muscles.Seven healthy adults were asked to stand upright with eyes closed and feet together on a stabilometer. The forward-backward sways of the head and BCG and the activity of the nuchal and soleus muscles were recorded polygraphically. The head sway and the nuchal muscle activity (head-nuchal muscle system) were analysed with a 2-dimensional feedback model to study vestibulo-spinal postural regulation. The sway of BCG and the soleus muscle activity (BCG-soleus muscle system) were analysed with a 2-dimensional feedback model to study proprio-spinal postural regulation.1. The determinants of the noise correlation matrix in the head-nuchal muscle system and in the BCG-soleus muscle system were close to 1, indicating good feedback.2. The order. of the autoregressive process, i. e. the length of the past sway forming the present sway, was greater in the head-nuchal muscle system than in the BCG-soleus muscle system.3. The power spectrum showed a higher power in the frequency range in the BCG sway than in the head sway. The correlogram showed that the correlation ratio decreased more rapidly to the base line in the BCG sway than in the head sway. These results indicate that regulation of the standing posture by proprioceptive reflexes is more minute than that by labyrinthine reflexes.4. The impulse responses calculated with the head sway as output and the nuchal muscle activity as input were divergent in 4 subjects. The impulse responses calculated with the head sway as input and the nuchal muscle activity as output were convergent in all 7. On the other hand, the impulse responses calculated with the BCG sway as output and the soleus muscle activity as input and with the BCG sway as input and the soleus muscle activity as output were convergent in all 7. These results suggest that the BCG-soleus muscle system provides greater stability than the head-nuchal muscle system.