Jeka J J, Lackner J R
Ashton Graybiel Spatial Orientation Laboratory, Brandeis University, Waltham, MA 02254.
Exp Brain Res. 1994;100(3):495-502. doi: 10.1007/BF02738408.
Touch and pressure stimulation of the body surface can strongly influence apparent body orientation, as well as the maintenance of upright posture during quiet stance. In the present study, we investigated the relationship between postural sway and contact forces at the fingertip while subjects touched a rigid metal bar. Subjects were tested in the tandem Romberg stance with eyes open or closed under three conditions of fingertip contact: no contact, touch contact (< 0.98 N of force), and force contact (as much force as desired). Touch contact was as effective as force contact or sight of the surroundings in reducing postural sway when compared to the no contact, eyes closed condition. Body sway and fingertip forces were essentially in phase with force contact, suggesting that fingertip contact forces are physically counteracting body sway. Time delays between body sway and fingertip forces were much larger with light touch contact, suggesting that the fingertip is providing information that allows anticipatory innervation of musculature to reduce body sway. The results are related to observations on precision grip as well as the somatosensory, proprioceptive, and motor mechanisms involved in the reduction of body sway.
对身体表面的触觉和压力刺激会强烈影响明显的身体方位，以及安静站立时直立姿势的维持。在本研究中，我们调查了受试者触摸刚性金属棒时姿势摆动与指尖接触力之间的关系。受试者在睁眼或闭眼的串联罗姆伯格姿势下，在三种指尖接触条件下进行测试：无接触、轻触接触（力小于0.98N）和用力接触（所需的任意力）。与无接触、闭眼条件相比，轻触接触在减少姿势摆动方面与用力接触或观察周围环境一样有效。身体摆动和指尖力在用力接触时基本同相，这表明指尖接触力在物理上抵消了身体摆动。轻触接触时，身体摆动和指尖力之间的时间延迟要大得多，这表明指尖正在提供信息，使肌肉组织能够进行预期的神经支配以减少身体摆动。这些结果与精确抓握的观察结果以及减少身体摆动所涉及的体感、本体感觉和运动机制有关。
