Gu Y, Wang Y, Wang S R
Laboratory for Visual Information Processing, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, 100101, PR, Beijing, China.
Neuroscience. 2001;104(1):153-9. doi: 10.1016/s0306-4522(01)00056-2.
The nucleus lentiformis mesencephali and the nucleus of the basal optic root in birds, homologous to the nucleus of the optic tract and the terminal nuclei of the accessory optic tract in mammals, are involved in optokinetic nystagmus. The present study provides the first electrophysiological evidence that reversible blockade of the pigeon nucleus of the basal optic root by lidocaine can change visual responsiveness of pretectal neurons in a direction-dependent manner. Thirty pretectal cells examined were classified as unidirectional (80%), bidirectional (10%) and omnidirectional (10%) cells according to their directional selectivity. Among the unidirectional cells, seven cells changed firing rates in all directions of motion, 11 changed visual responses only in the preferred directions and six others did not change their responsiveness during lidocaine. Most of the bidirectional cells changed firing rates in the temporonasal direction, and two-thirds of the omnidirectional cells showed these changes in all directions. Thirteen lidocaine administration sites were marked within the nucleus of the basal optic root and 19 recording sites were marked within the nucleus lentiformis mesencephali. This histological verification indicates that the effects of lidocaine blockade in the accessory optic nucleus on the directional selectivity and visual responsiveness of pretectal cells appear to be related, to some extent, to the location of drug injections in the nucleus of the basal optic root. This study has found that visual neurons in the nucleus of the basal optic root, which predominantly prefer vertical and backward motion, could modulate the directional selectivity and visual responsiveness of neurons in the nucleus lentiformis mesencephali, which mainly prefer horizontal motion. It is conceivable that both nuclei work together in coordination and in competition during optokinetic nystagmus.
鸟类的豆状中脑核和基底视根核，与哺乳动物的视束核和副视束终核同源，参与视动性眼震。本研究提供了首个电生理证据，即利多卡因对鸽基底视根核的可逆性阻断可使顶盖前神经元的视觉反应性以方向依赖的方式发生改变。根据其方向选择性，所检测的30个顶盖前细胞被分类为单向（80%）、双向（10%）和全向（10%）细胞。在单向细胞中，7个细胞在所有运动方向上都改变了放电频率，11个细胞仅在偏好方向上改变了视觉反应，另外6个细胞在利多卡因作用期间没有改变其反应性。大多数双向细胞在颞鼻方向上改变了放电频率，三分之二的全向细胞在所有方向上都出现了这些变化。在基底视根核内标记了13个利多卡因给药部位，在豆状中脑核内标记了19个记录部位。这种组织学验证表明，副视核中利多卡因阻断对顶盖前细胞方向选择性和视觉反应性的影响，在一定程度上似乎与基底视根核内药物注射的位置有关。本研究发现，主要偏好垂直和向后运动的基底视根核中的视觉神经元，可以调节主要偏好水平运动的豆状中脑核中神经元的方向选择性和视觉反应性。可以想象，在视动性眼震过程中，这两个核协同工作并相互竞争。
