Grüsser-Cornehls U, Niemschynski A, Plassmann W
Department of physiology, Freie Universität Berlin, Germany.
Exp Brain Res. 1995;107(1):17-25. doi: 10.1007/BF00228012.
Vestibular nuclei (Vn) neurons and floccular Purkinje (P) cells of unanesthetized paralyzed mice (B6CBA) responding to horizontal angular acceleration in the dark (type I and type II neurons) were studied by extracellular recordings with micropipettes while varying either the frequency (and velocity) or the amplitude (and velocity) of the sinusoidal rotation, keeping the respective third parameter constant. Phase and sensitivity were analyzed by a Fourier analysis and a "best sine fitting" program. Recording sites were localized by means of small iontophoretically applied horseradish peroxidase markings. The neuronal response amplitude at fundamental frequency (determined from peristimulus time histograms) increased with the frequency and amplitude of the sinusoidal rotation for both Vn and floccular neurons (0.05-0.5 Hz; +/- 60 degrees amplitude). Stimulus frequency/response amplitude and stimulus amplitude/response amplitude curves of floccular neurons were distinctly lower in magnitude than those of Vn neurons (P < 0.01) Accordingly, the sensitivity (re velocity) curves of Vn neurons and P cells differed in magnitude significantly (decreasing slightly with increasing stimulus frequency and amplitude in Vn neurons and more or less independent of stimulus parameters in floccular P cells). Response amplitudes of type I and type II neurons did not differ from each other. Phase advance relative to head angular velocity in the midfrequency range in Vn neurons was very small, indicating a head velocity signal carried by the Vn neurons. In floccular P cells phase advance was only small at 0.1 Hz (amplitude +/- 35 degrees), but increased with augmenting frequency to 140 degrees at 0.5 Hz. With a constant stimulus frequency (0.3 Hz) and varied stimulus amplitude, phase advance was 90 degrees at +/- 20 degrees amplitude and 60 degrees amplitude. Data are shown for the first time in which both the stimulus frequency and the stimulus amplitude have been varied in the same species and in the same neurons. The results demonstrate that the single data are in general well within the range of those found in other species, but they demonstrate further that phase behavior is dependent on the stimulus paradigm. The data provide the basis for comparative studies with mutant mice.
采用微电极细胞外记录法，在黑暗环境中，对未麻醉的瘫痪小鼠（B6CBA）的前庭核（Vn）神经元和绒球浦肯野（P）细胞对水平角加速度的反应（I型和II型神经元）进行了研究。实验中改变正弦旋转的频率（和速度）或幅度（和速度），同时保持第三个参数不变。通过傅里叶分析和“最佳正弦拟合”程序分析相位和灵敏度。通过微量离子电泳施加辣根过氧化物酶标记来定位记录位点。对于Vn神经元和绒球神经元（0.05 - 0.5Hz；幅度±60度），基频下的神经元反应幅度（由刺激后时间直方图确定）随正弦旋转的频率和幅度增加而增加。绒球神经元的刺激频率/反应幅度和刺激幅度/反应幅度曲线在幅度上明显低于Vn神经元（P < 0.01）。因此，Vn神经元和P细胞的灵敏度（相对于速度）曲线在幅度上有显著差异（Vn神经元中随刺激频率和幅度增加略有下降，而绒球P细胞中或多或少与刺激参数无关）。I型和II型神经元的反应幅度彼此无差异。Vn神经元在中频范围内相对于头部角速度的相位超前非常小，表明Vn神经元携带头部速度信号。在绒球P细胞中，相位超前在0.1Hz（幅度±35度）时仅很小，但随频率增加到0.5Hz时增加到140度。在恒定刺激频率（0.3Hz）和变化的刺激幅度下，相位超前在幅度±20度时为90度，在幅度±60度时为60度。首次展示了在同一物种和同一神经元中同时改变刺激频率和刺激幅度的数据。结果表明，单个数据总体上处于其他物种中发现的数据范围内，但进一步表明相位行为取决于刺激模式。这些数据为与突变小鼠的比较研究提供了基础。
