We recently demonstrated in decerebrate and conscious cat preparations that hindlimb somatosensory inputs converge with vestibular afferent input onto neurons in multiple CNS locations that participate in balance control. While it is known that head position and limb state modulate postural reflexes, presumably through vestibulospinal and reticulospinal pathways, the combined influence of the two inputs on the activity of neurons in these brainstem regions is unknown. In the present study, we evaluated the responses of vestibular nucleus (VN) neurons to vestibular and hindlimb stimuli delivered separately and together in conscious cats. We hypothesized that VN neuronal firing during activation of vestibular and limb proprioceptive inputs would be well-fit by an additive model. Extracellular single-unit recordings were obtained from VN neurons. Sinusoidal whole-body rotation in the roll plane was used as the search stimulus. Units responding to the search stimulus were tested for their responses to 10° ramp-and-hold roll body rotation, 60° extension hindlimb movement, and both movements delivered simultaneously. Composite response histograms were fit by a model of low and high pass filtered limb and body position signals using least squares nonlinear regression. We found that VN neuronal activity during combined vestibular and hindlimb proprioceptive stimulation in the conscious cat is well-fit by a simple additive model for signals with similar temporal dynamics. The mean R²value for goodness of fit across all units was 0.74 ±0.17. It is likely that VN neurons that exhibit these integrative properties participate in adjusting vestibulospinal outflow in response to limb state.

中文翻译：

---

前庭核神经元对前庭和后肢输入的整合：多感觉对姿势控制的影响。

我们最近在去大脑和有意识的猫准备中证明，后肢体感输入与前庭传入输入会聚到参与平衡控制的多个 CNS 位置的神经元上。虽然已知头部位置和肢体状态调节姿势反射，可能是通过前庭脊髓和网状脊髓通路，但两种输入对这些脑干区域神经元活动的综合影响尚不清楚。在本研究中，我们评估了前庭核 (VN) 神经元对前庭和后肢刺激的反应，这些刺激在有意识的猫中分别和一起传递。我们假设前庭和肢体本体感受输入激活期间的 VN 神经元放电将非常适合加性模型。从 VN 神经元获得细胞外单单元记录。滚动平面中的正弦全身旋转用作搜索刺激。测试响应搜索刺激的单元对 10° 斜坡和保持滚动体旋转、60° 伸展后肢运动以及同时传递的两个运动的响应。通过使用最小二乘非线性回归的低通和高通滤波肢体和身体位置信号模型拟合复合响应直方图。我们发现，在有意识的猫的前庭和后肢本体感受联合刺激期间，VN 神经元活动非常适合具有相似时间动态的信号的简单加法模型。平均 R 60° 伸展后肢运动，两个运动同时进行。通过使用最小二乘非线性回归的低通和高通滤波肢体和身体位置信号模型拟合复合响应直方图。我们发现，在有意识的猫的前庭和后肢本体感受联合刺激期间，VN 神经元活动非常适合具有相似时间动态的信号的简单加法模型。平均 R 60° 伸展后肢运动，两个运动同时进行。通过使用最小二乘非线性回归的低通和高通滤波肢体和身体位置信号模型拟合复合响应直方图。我们发现，在有意识的猫的前庭和后肢本体感受联合刺激期间，VN 神经元活动非常适合具有相似时间动态的信号的简单加法模型。平均 R²所有单位的拟合优度值为 0.74 ±0.17。表现出这些综合特性的 VN 神经元很可能参与调节前庭脊髓外流以响应肢体状态。