Gdowski G T, McCrea R A
Department of Neurobiology, Pharmacology, and Physiology, University of Chicago, Chicago, Illinois 60637, USA.
J Neurophysiol. 1999 Jul;82(1):436-49. doi: 10.1152/jn.1999.82.1.436.
Single-unit recordings were obtained from 107 horizontal semicircular canal-related central vestibular neurons in three alert squirrel monkeys during passive sinusoidal whole-body rotation (WBR) while the head was free to move in the yaw plane (2.3 Hz, 20 degrees /s). Most of the units were identified as secondary vestibular neurons by electrical stimulation of the ipsilateral vestibular nerve (61/80 tested). Both non-eye-movement (n = 52) and eye-movement-related (n = 55) units were studied. Unit responses recorded when the head was free to move were compared with responses recorded when the head was restrained from moving. WBR in the absence of a visual target evoked a compensatory vestibulocollic reflex (VCR) that effectively reduced the head velocity in space by an average of 33 +/- 14%. In 73 units, the compensatory head movements were sufficiently large to permit the effect of the VCR on vestibular signal processing to be assessed quantitatively. The VCR affected the rotational responses of different vestibular neurons in different ways. Approximately one-half of the units (34/73, 47%) had responses that decreased as head velocity decreased. However, the responses of many other units (24/73) showed little change. These cells had signals that were better correlated with trunk velocity than with head velocity. The remaining units had responses that were significantly larger (15/73, 21%) when the VCR produced a decrease in head velocity. Eye-movement-related units tended to have rotational responses that were correlated with head velocity. On the other hand, non-eye-movement units tended to have rotational responses that were better correlated with trunk velocity. We conclude that sensory vestibular signals are transformed from head-in-space coordinates to trunk-in-space coordinates on many secondary vestibular neurons in the vestibular nuclei by the addition of inputs related to head rotation on the trunk. This coordinate transformation is presumably important for controlling postural reflexes and constructing a central percept of body orientation and movement in space.
在三只清醒的松鼠猴被动进行正弦全身旋转（WBR）期间，头部可在偏航平面自由移动（2.3 Hz，20度/秒），从107个与水平半规管相关的中枢前庭神经元记录到单单位活动。通过电刺激同侧前庭神经，大多数单位被鉴定为次级前庭神经元（80个中测试了61个）。对非眼动相关单位（n = 52）和眼动相关单位（n = 55）都进行了研究。将头部自由移动时记录的单位反应与头部被限制移动时记录的反应进行比较。在没有视觉目标的情况下进行WBR诱发了一种补偿性前庭颈反射（VCR），该反射有效地将头部在空间中的速度平均降低了33±14%。在73个单位中，补偿性头部运动足够大，从而可以定量评估VCR对前庭信号处理的影响。VCR以不同方式影响不同前庭神经元的旋转反应。大约一半的单位（34/73，47%）的反应随着头部速度降低而减小。然而，许多其他单位（24/73）的反应几乎没有变化。这些细胞的信号与躯干速度的相关性比与头部速度的相关性更好。其余单位在VCR使头部速度降低时反应显著更大（15/73，21%）。眼动相关单位的旋转反应往往与头部速度相关。另一方面，非眼动单位的旋转反应往往与躯干速度的相关性更好。我们得出结论，通过在前庭核中的许多次级前庭神经元上添加与头部在躯干上的旋转相关的输入，感觉前庭信号在空间中从头部坐标转换为躯干坐标。这种坐标转换大概对于控制姿势反射以及构建身体在空间中的方向和运动的中枢感知很重要。
