Angelaki D E, Bush G A, Perachio A A
Department of Otolaryngology, University of Texas Medical Branch, Galveston 77555.
J Neurosci. 1993 Apr;13(4):1403-17. doi: 10.1523/JNEUROSCI.13-04-01403.1993.
Response properties of vertical (VC) and horizontal (HC) canal/otolith-convergent vestibular nuclei neurons were studied in decerebrate rats during stimulation with sinusoidal linear accelerations (0.2-1.4 Hz) along different directions in the head horizontal plane. A novel characteristic of the majority of tested neurons was the nonzero response often elicited during stimulation along the "null" direction (i.e., the direction perpendicular to the maximum sensitivity vector, Smax). The tuning ratio (Smin gain/Smax gain), a measure of the two-dimensional spatial sensitivity, depended on stimulus frequency. For most vestibular nuclei neurons, the tuning ratio was small at the lowest stimulus frequencies and progressively increased with frequency. Specifically, HC neurons were characterized by a flat Smax gain and an approximately 10-fold increase of Smin gain per frequency decade. Thus, these neurons encode linear acceleration when stimulated along their maximum sensitivity direction, and the rate of change of linear acceleration (jerk) when stimulated along their minimum sensitivity direction. While the Smax vectors were distributed throughout the horizontal plane, the Smin vectors were concentrated mainly ipsilaterally with respect to head acceleration and clustered around the naso-occipital head axis. The properties of VC neurons were distinctly different from those of HC cells. The majority of VC cells showed decreasing Smax gains and small, relatively flat, Smin gains as a function of frequency. The Smax vectors were distributed ipsilaterally relative to the induced (apparent) head tilt. In type I anterior or posterior VC neurons, Smax vectors were clustered around the projection of the respective ipsilateral canal plane onto the horizontal head plane. These distinct spatial and temporal properties of HC and VC neurons during linear acceleration are compatible with the spatiotemporal organization of the horizontal and the vertical/torsional ocular responses, respectively, elicited in the rat during linear translation in the horizontal head plane. In addition, the data suggest a spatially and temporally specific and selective otolith/canal convergence. We propose that the central otolith system is organized in canal coordinates such that there is a close alignment between the plane of angular acceleration (canal) sensitivity and the plane of linear acceleration (otolith) sensitivity in otolith/canal-convergent vestibular nuclei neurons.
在去大脑的大鼠中，研究了垂直（VC）和水平（HC）半规管/耳石汇聚型前庭核神经元在头部水平面内沿不同方向进行正弦线性加速度（0.2 - 1.4 Hz）刺激时的反应特性。大多数被测试神经元的一个新特征是，在沿“零”方向（即垂直于最大敏感向量Smax的方向）刺激时，常常会引发非零反应。调谐比（Smin增益/Smax增益）作为二维空间敏感性的一种度量，取决于刺激频率。对于大多数前庭核神经元而言，在最低刺激频率下调谐比很小，并且随频率逐渐增加。具体而言，HC神经元的特征是Smax增益平坦，且每频率十年Smin增益大约增加10倍。因此，这些神经元在沿其最大敏感方向刺激时编码线性加速度，而在沿其最小敏感方向刺激时编码线性加速度的变化率（加加速度）。虽然Smax向量分布在整个水平面内，但Smin向量主要集中在相对于头部加速度的同侧，并聚集在鼻枕头部轴周围。VC神经元的特性与HC细胞明显不同。大多数VC细胞的Smax增益随频率降低，Smin增益小且相对平坦。Smax向量相对于诱发（表观）头部倾斜分布在同侧。在I型前或后VC神经元中，Smax向量聚集在相应同侧半规管平面在水平头部平面上的投影周围。HC和VC神经元在直线加速度期间这些独特的空间和时间特性分别与大鼠在水平头部平面直线平移期间引发的水平和垂直/扭转眼动反应的时空组织相匹配。此外，数据表明存在空间和时间上特定且选择性的耳石/半规管汇聚。我们提出，中枢耳石系统以半规管坐标组织，使得在耳石/半规管汇聚型前庭核神经元中，角加速度（半规管）敏感平面与线性加速度（耳石）敏感平面之间存在紧密对齐。
