Acute adaptation of the vestibuloocular reflex: Signal processing by floccular and ventral parafloccular Purkinje cells
Acute adaptation of the vestibuloocular reflex: Signal processing by floccular and ventral parafloccular Purkinje cells
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DOI：
10.1152/jn.2001.85.5.2267
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发表时间：
2001-05-01
影响因子：
2.5
通讯作者：
Highstein, SM
中科院分区：
文献类型：
--
作者：
Hirata, Y;Highstein, SM
垂直前庭眼反射（VVOR），定义为眼速度/头速度的增益适应在松鼠猴采用视觉前庭不匹配刺激。在黑暗中测量的VVOR增益可以训练到0.4和1.5之间的值。在变增益训练前和训练过程中，记录了警觉松鼠猴的绒球和腹侧副绒球垂直带浦肯野细胞的单单位活动。我们的目标是评估增益变化的学习部位。为了帮助评估，垂直视动反射（VOKR）和VVOR的模型被构建成由絮状物和nonfloccular系统分为子系统的基础上已知的解剖结构和输入和输出参数。明确描述了三种通过苔藓纤维输入到絮状浦肯野细胞的输入，即前庭、视觉（视网膜滑动）和眼运动的传出复制。每个子系统（增益和相位）的特性，确定在不同的VOR增益重建单单位活动的浦肯野细胞在VOKR和VVOR与多元线性回归模型组成的感觉输入和运动输出信号。通过评估回归后的残差和预测浦肯野细胞在视觉-前庭不匹配范例中的活性来检查模型的适当性。结果表明，在传递前庭信号的前房/絮状子系统和传递前庭信号的非絮状子系统中，VVOR适应的识别特征发生了平行变化，而在其他子系统中，即传递传出复制或视觉信号的前房/絮状子系统，传递视觉信号的非絮状子系统，以及将浦肯野细胞活性转化为眼球运动的后絮凝子系统。结果表明，多个网站的VVOR运动学习，包括两个绒球和非绒球途径。非絮状前庭子系统中的增益变化是在正确的方向上引起VOR增益适应，而前絮状/絮状前庭子系统中的变化是不正确的（反补偿）。这种明显不正确的方向变化可能有助于防止通过传出复制途径的正反馈引起的VOR的不稳定。
The gain of the vertical vestibuloocular reflex (VVOR), defined as eye velocity/head velocity was adapted in squirrel monkeys by employing visual-vestibular mismatch stimuli. VVOR gain, measured in the dark, could be trained to values between 0.4 and 1.5. Single-unit activity of vertical zone Purkinje cells was recorded from the flocculus and ventral paraflocculus in alert squirrel monkeys before and during the gain change training. Our goal was to evaluate the site(s) of learning of the gain change. To aid in the evaluation, a model of the vertical optokinetic reflex (VOKR) and VVOR was constructed consisting of floccular and nonfloccular systems divided into subsystems based on the known anatomy and input and output parameters. Three kinds of input to floccular Purkinje cells via mossy fibers were explicitly described, namely vestibular, visual (retinal slip), and efference copy of eye movement. The characteristics of each subsystem (gain and phase) were identified at different VOR gains by reconstructing single-unit activity of Purkinje cells during VOKR and VVOR with multiple linear regression models consisting of sensory input and motor output signals. Model adequacy was checked by evaluating the residual following the regressions and by predicting Purkinje cells' activity during visual-vestibular mismatch paradigms. As a result, parallel changes in identified characteristics with VVOR adaptation were found in the prefloccular/floccular subsystem that conveys vestibular signals and in the nonfloccular subsystem that conveys vestibular signals, while no change was found in other subsystems, namely prefloccular/floccular subsystems conveying efference copy or visual signals, nonfloccular subsystem conveying visual signals, and postfloccular subsystem transforming Purkinje cell activity to eye movements. The result suggests multiple sites for VVOR motor learning including both flocculus and nonflocculus pathways. The gain change in the nonfloccular vestibular subsystem was in the correct direction to cause VOR gain adaptation while the change in the prefloccular/ floccular vestibular subsystem was incorrect (anti-compensatory). This apparent incorrect directional change might serve to prevent instability of the VOR caused by positive feedback via the efference copy pathway.