Evidence for a photosensitive region in the caudal mesencephalon of the turtle brain.
Evidence for a photosensitive region in the caudal mesencephalon of the turtle brain.
复制标题
乌龟大脑尾部中脑存在光敏区域的证据。
DOI：
10.1007/s002210050360
复制
发表时间：
1998
影响因子：
2
通讯作者：
Keifer,J
中科院分区：
文献类型：
--
作者：
Anderson,CW;Keifer,J
用体外提取的甲鱼脑干-小脑标本，当光照射到脑干上时，记录到外展神经的爆发性放电。这种突发性放电很可能代表了眨眼反射的神经关联。增加光刺激强度可将反应潜伏期从数秒缩短到约1-2个S。遮盖光源时未记录到反应。当红外光被阻挡时，这种反应就会出现，只有当光谱中包含的波长低于大约550纳米时，才能产生这种反应。损伤实验表明，光敏区位于滑车神经的尾侧和三叉神经的吻侧。单单位微电极记录表明，这一区域在黑暗中是音调活跃的，而活动被光抑制。药理学结果表明，作为5-羟色胺能拮抗剂的化合物可以阻断光反应，去甲肾上腺素受体拮抗剂(α或β)要么没有作用，要么作用不同。综上所述，这些数据表明，海龟大脑中一个类似峡视的区域对直射光线是光敏的，并激活了控制眼睛运动的神经回路。
Using an in vitro brainstem-cerebellum preparation from the turtleChrysemys picta,burst discharge was recorded from the abducens nerve when light was directed on the brainstem. This burst discharge likely represents a neural correlate of the eye-blink reflex. Increasing the intensity of the light stimulus reduced the response latency from a duration of many seconds to approximately 1–2 s. No response was recorded when the light source was covered. The response was present when infrared light was blocked, and it could only be produced when the light spectra contained wavelengths below approximately 550 nm. Lesion experiments reveal that the photosensitive area is located caudal to the trochlear nerve and rostral to the trigeminal nerve. Single-unit microelectrode recordings demonstrate that this region is tonically active in the dark and that activity is suppressed by light. Pharmacological results show that the light response is blocked by application of compounds that act as serotonergic antagonists, and that antagonists of noradrenergic receptors (α or β) either have no effect or their actions are variable. Taken together, these data suggest that an isthmo-optic-like area in the turtle brain is photosensitive to direct light and activates neural circuits that control eye movements.