Mechanisms of vestibular compensation

为了明确前庭代偿期哪些类型的前庭核神经元发生了活动变化，我们必须了解完整大鼠前庭神经元的膜电生理特性。在我们以前的研究中，使用全细胞膜片钳技术在大鼠脑干切片，我们的特点是三个膜特性的前庭内侧核（MVN）的神经元：后超极化（AHP）的配置文件，放电模式，并响应模式超极化电流脉冲。然而，膜的性质尚未确定在体内，其功能的意义还没有得到澄清。为了解决这些问题，我们应用全细胞膜片钳记录方法在体内制备的年轻成年大鼠和调查的膜和自发放电特性。我们发现了三个层次分析法，三个放电模式，和三个反应模式的超极化电流脉冲在MVN神经元在体内，其特征在于在我们以前的体外研究。这表明这三种膜特性适用于体内。对MVN神经元在体和离体放电特性的分析表明，具有慢成分的AHP神经元[AHP（s+）]的峰间间期变异系数小于不具有慢成分的AHP神经元[AHP（s-）]和具有后去极化的AUP神经元[AHP（s+）with ADP]。结果表明，呈现AHP（s+）的神经元为规则放电神经元，而呈现AHP（s-）和含ADP的AHP（s+）的神经元为不规则放电神经元。

To clarify which types of vestibular nucleus neurons change their activity during the period of the vestibular compensation, we must know electrophysiological membrane properties of vestibular neurons in intact rats. In our previous study using the whole-cell patch clamp technique in rat brainstem slices, we characterized three membrane properties of neurons in the medial vestibular nucleus (MVN) : afterhyperpolarization (AHP) profiles, firing patterns, and response patterns to hyperpolarizing current pulses. However, the membrane properties have not been ascertained in vivo and their functional significance has not been clarified. To address these issues, we applied the whole-cell patch clamp recording method to in vivo preparations of young adult rats and investigated the membrane and spontaneous discharge properties. We found three AHP profiles, three firing patterns, and three response patterns to hyperpolarizing current pulses in MVN neurons in vivo, which were characterized in our previous in vitro study. This indicates that the three membrane properties are applicable in vivo. The analysis of discharge properties of MVN neurons both in vivo and in vitro revealed that the coefficient of variation of interspike intervals was smaller in neurons exhibiting AHP with a slow component [AHP(s+)] than in those exhibiting AHP without a slow component [AHP(s-)] and AUP with afterdepolarization followed by a slow component [AHP(s+) with ADP]. The result indicates that neurons exhibiting AHP(s+) are regular discharging neurons, whereas neurons exhibiting AHP(s-) and AHP(s+) with ADP are irregular discharging neurons.