Dizio P, Lackner J R
Ashton Graybiel Spatial Orientation Laboratory, Brandeis University, Waltham, MA 02254-9110.
Vision Res. 1992 Jan;32(1):111-20. doi: 10.1016/0042-6989(92)90119-4.
Velocity storage is an important aspect of sensory-motor control of body orientation. The effective decay rate and three-dimensional organization of velocity storage are dependent upon body orientation relative to gravity and also are influenced by gravitoinertial force (G) level. Several of the inputs to velocity storage including otolithic, somatosensory, proprioceptive, and possibly motor are highly dependent on G level. To see whether the G dependency of velocity storage is related to changes in the effective coupling of individual sensory inputs to the velocity storage mechanism or to alterations in the time constant of velocity storage per se, we have studied horizontal vestibular nystagmus, horizontal optokinetic after nystagmus (OKAN) and vertical vestibular nystagmus as a function of force level. Horizontal OKAN and vestibular nystagmus both showed no effect of G level on their initial or peak slow phase velocities but their decay rates were quicker in 0G and 1.8G than in 1G. Vertical vestibular nystagmus also showed no effect of G level on peak velocity but decayed quicker in 0G relative to 1G. These-findings indicate that the intrinsic decay rate of a common velocity storage mechanism is affected by the magnitude of G. A negligible amount of slow phase eye velocity was observed in planes outside the planes of stimulation, thus short-term changes in G across multiple body axes can change velocity storage, but the change is restricted to the axis common to the rotary stimulus and the G vector.
速度存储是身体定向感觉运动控制的一个重要方面。速度存储的有效衰减率和三维组织取决于身体相对于重力的定向，并且还受到重力惯性力（G）水平的影响。速度存储的几个输入，包括耳石、体感、本体感觉以及可能的运动输入，都高度依赖于G水平。为了探究速度存储对G的依赖性是与个体感觉输入与速度存储机制的有效耦合变化有关，还是与速度存储本身的时间常数改变有关，我们研究了水平前庭眼震、水平视动性眼震后眼震（OKAN）和垂直前庭眼震随力水平的变化。水平OKAN和前庭眼震在其初始或峰值慢相速度上均未显示出G水平的影响，但它们在0G和1.8G时的衰减率比在1G时更快。垂直前庭眼震在峰值速度上也未显示出G水平的影响，但在0G时相对于1G衰减更快。这些发现表明，一个共同的速度存储机制的固有衰减率受G大小的影响。在刺激平面之外的平面中观察到可忽略不计的慢相眼速度，因此，跨多个身体轴的G的短期变化可以改变速度存储，但这种变化仅限于旋转刺激和G向量共有的轴。
