Intracellular characterization of neurons in the locust brain signaling impending collision.
Intracellular characterization of neurons in the locust brain signaling impending collision.
复制标题
蝗虫大脑中神经元的细胞内特征，发出即将发生的碰撞信号。
DOI：
10.1152/jn.1996.75.3.986
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发表时间：
1996
影响因子：
2.5
通讯作者：
F. Rind
中科院分区：
文献类型：
--
作者：
F. Rind
1. 在对快速接近的物体的反应中，细胞内记录显示蝗虫小叶巨大运动检测（LGMD）神经元的兴奋呈指数级增长，特别是在物体接近的最后阶段。在物体运动停止后，LGMD中的抑制电位帮助终止这种兴奋。LGMD的兴奋在物体衰退后产生一个短暂的、恒定的延迟，但被超极化电位迅速切断。这些超极化电位在LGMD中的时间是可变的，它们在物体后退后的潜伏期最短，模拟的运动速度最快。超极化电位持续50-300 ms，并常伴有再激发。观察到的LGMD的超极化可以在没有任何先前激励的情况下发生，并且伴随着可测量的电导增加。超极化可能是抑制性突触后电位（psp）。细胞内记录的抑制性PSPs （IPSPs）的行为与Rind和Bramwell描述的神经网络中的前馈抑制环的行为非常相似。LGMD对接近或后退物体的偏好在起始和结束距离的很大范围内仍然存在。通过测量膜电位和峰值速率，可以发现，在起始距离为200 - 2100 mm，接近速度为0.5-2 m/s时，对物体接近的响应仍然是单峰的。这些结果证实了Rind和Bramwell描述的神经网络预测的行为，但与Rind和Simmons的发现相矛盾，迫使人们重新评估该研究中使用的一些机械视觉刺激的适用性。3. 为了使LGMD神经元的去极化在图像边缘的运动中保持或增加，边缘必须在眼睛上以越来越快的速度移动。膜电位在边缘运动结束前下降，边缘运动速度恒定。4. 第二个已识别的神经元LGMD2也显示出对接近的物体有方向性反应。在LGMD和LGMD2神经元中，突触后抑制形成了对物体运动的定向反应。
1. In response to a rapidly approaching object, intracellular recordings show that excitation in the locust lobula giant movement detecting (LGMD) neuron builds up exponentially, particularly during the final stages of object approach. After the cessation of object motion, inhibitory potentials in the LGMD then help to terminate this excitation. Excitation in the LGMD follows object recession with a short, constant latency but is cut back rapidly by hyperpolarizing potentials. The timing of these hyperpolarizing potentials in the LGMD is variable, and their latency following object recession is shortest with the highest velocities of motion simulated. The hyperpolarizing potentials last from 50-300 ms and are often followed by re-excitation. The observed hyperpolarizations of the LGMD can occur without any preceding excitation and are accompanied by a measurable conductance increase. The hyperpolarizations are likely to be inhibitory postsynaptic potentials (PSPs). The behavior of the intracellularly recorded inhibitory PSPs (IPSPs) closely parallels that of the feed forward inhibitory loop in the neural network described by Rind and Bramwell. 2. The preference of the LGMD for approaching versus receding objects remains over a wide range of starting and finishing distances. The response to object approach, measured both as membrane potential and spike rate, remains single peaked with starting distances of between 200 and 2,100 mm, and approach speeds of 0.5-2 m/s. These results confirm the behavior predicted by the neural network described by Rind and Bramwell but contradicts the findings of Rind and Simmons, forcing a re-evaluation of the suitability of some of the mechanical visual stimuli used in that study. 3. For depolarization of the LGMD neuron to be maintained or increased throughout the motion of image edges, the edges must move with increasing velocity over the eye. Membrane potential declines before the end of edge motion with constant velocities of edge motion. 4. A second identified neuron, the LGMD2 also is shown to respond directionally to approaching objects. In both the LGMD and LGMD2 neurons, postsynaptic inhibition shapes the directional response to object motion.