Raphan T, Dai M, Maruta J, Waespe W, Henn V, Suzuki J I, Cohen B
Department of Computer and Information Science, Brooklyn College, City University of New York 11210, USA.
Ann N Y Acad Sci. 1999 May 28;871:181-94. doi: 10.1111/j.1749-6632.1999.tb09184.x.
Pitching the head while rotating (PWR) combines periodic activation of the semicircular canals and the otoliths to generate pitch and roll eye deviations and continuous horizontal nystagmus. Monkeys were tested after individual pairs of semicircular canals were plugged and single units were recorded in the vestibular nerve while the animals were sinusoidally pitched 20-40 deg about a spatial horizontal axis with 5- and 16-s periods and simultaneously rotated about a spatial vertical axis at 30-120 deg/s. As previously shown, the steady-state horizontal response disappeared after plugging the vertical semicircular canals, but was maintained when the lateral canals were plugged. When the left anterior and right posterior canal (LARP) pair was left intact, the steady-state response depended on the axis about which the pitching took place. When the axis was normal to the LARP plane, there was no steady-state response. When the pitching axis was perpendicular to the LARP normal, the response was maximal. Firing rates of otolith units were approximately in phase with pitch position, and the addition of rotation about a vertical axis did not change the response. Lateral canal units did not have a steady-state modulation during pitch or constant velocity rotation. During PWR, they oscillated at twice the pitch frequency. This corresponded to the frequency at which the canal was maximally activated as it aligned with the plane of rotation. The amplitude of modulation increased proportionally to rotational velocity, but the phase remained the same. These characteristics were unchanged during roll while rotating (RWR), which induces little continuous nystagmus. Anterior and posterior canal units were maximally excited near pitch-velocity maxima and minima, respectively, during pure pitching. During PWR, however, the phases of both components simultaneously shifted toward each other and toward being in phase with otolith units. The peak excitation tended toward a forward-pitch position when the rotation was to the ipsilateral side, and toward a backward pitch position when the rotation was to the contralateral side. With 120-deg/s rotation during a 16-s pitch period, the phase difference between anterior and posterior canal units was as small as 17 deg. These data support the postulate that the correlation between vertical canal and otolith units is the critical factor in generating continuous unidirectional horizontal nystagmus during PWR.
旋转时俯仰（PWR）结合了半规管和耳石的周期性激活，以产生俯仰和横滚眼偏斜以及持续的水平眼震。在成对的半规管被堵塞后对猴子进行测试，并在前庭神经中记录单个神经元，同时让动物围绕空间水平轴以5秒和16秒的周期进行20 - 40度的正弦俯仰，并同时围绕空间垂直轴以30 - 120度/秒的速度旋转。如先前所示，堵塞垂直半规管后稳态水平反应消失，但堵塞外侧半规管时该反应得以维持。当左前半规管和右后半规管（LARP）对保持完整时，稳态反应取决于俯仰所围绕的轴。当轴垂直于LARP平面时，没有稳态反应。当俯仰轴垂直于LARP法线时，反应最大。耳石神经元的放电频率大致与俯仰位置同相，并且绕垂直轴的旋转添加并未改变反应。外侧半规管神经元在俯仰或匀速旋转期间没有稳态调制。在PWR期间，它们以俯仰频率的两倍振荡。这对应于半规管与旋转平面一致时被最大激活所对应的频率。调制幅度与旋转速度成比例增加，但相位保持不变。在旋转时横滚（RWR）期间这些特征不变，RWR几乎不会诱发持续的眼震。在纯俯仰期间，前半规管和后半规管神经元分别在俯仰速度最大值和最小值附近被最大程度激活。然而，在PWR期间，两个成分的相位同时相互靠近并与耳石神经元同相。当旋转为同侧时，峰值兴奋倾向于前俯仰位置；当旋转为对侧时，倾向于后俯仰位置。在16秒俯仰周期内以120度/秒旋转时，前半规管和后半规管神经元之间的相位差小至17度。这些数据支持这样的假设，即垂直半规管和耳石神经元之间的相关性是在PWR期间产生持续单向水平眼震的关键因素。
