Gilbert C, Gronenberg W, Strausfeld N J
Department of Entomology, Cornell University, Ithaca, New York 14853, USA.
J Comp Neurol. 1995 Oct 16;361(2):285-97. doi: 10.1002/cne.903610207.
In tethered flying flies, moving contrast gratings or small spots elicit head movements which are suited to track retinal images moving at velocities up to 3,000 degrees/sec (about 50 Hz contrast frequency for gratings of spatial wavelength 15 degrees). To investigate the neural basis of these movements we have combined videomicroscopy with electrophysiological stimulation and recording to demonstrate that excitation of prothoracic motor neurons projecting in the anterodorsal (ADN) and frontal nerves (FN), respectively, generates the yaw and roll head movements measured behaviorally. Electrical stimulation of the ADN produces head yaw. The visual stimuli which excite the two ADN motor neurons (ADN MNs) are horizontal motion of gratings or spots moving clockwise around the yaw axis in the case of the right ADN (counterclockwise for left ADN). Activity is inhibited by motion in the opposite direction. Spatial sensitivity varies in the yaw plane with a maximum between 0 degree and 40 degrees ipsilaterally, but both excitation and inhibition are elicited out to 80 degrees in the ipsilateral and contralateral fields. ADN MNs respond to contrast frequencies up to 15-20 Hz, with a peak around 2-4 Hz for grating motion in the excitatory or inhibitory directions. Electrical stimulation of the FN primarily elicits roll down to the ipsilateral side. The one FN MN consistently driven by visual stimulation is excited by downward motion and inhibited by upward motion at 80 degrees azimuth in the ipsilateral visual field. At -80 degrees contralateral, visual motion has the opposite effect: Upward is excitatory and downward is inhibitory. The FN MN is tuned to contrast frequencies in the same range as the ADN MNs, with peak sensitivity around 4 Hz. The functional organization of inputs to the ADN and FN is discussed with respect to identified visual interneurons and parallel pathways controlling motor output.
在系留飞行的苍蝇中，移动的对比光栅或小斑点会引发头部运动，这些运动适合追踪速度高达3000度/秒（对于空间波长为15度的光栅，对比度频率约为50赫兹）移动的视网膜图像。为了研究这些运动的神经基础，我们将视频显微镜与电生理刺激和记录相结合，以证明分别在前背侧（ADN）和额神经（FN）中投射的前胸运动神经元的兴奋会产生行为上测量到的偏航和滚转头部运动。对ADN的电刺激会产生头部偏航。激发两个ADN运动神经元（ADN MNs）的视觉刺激是光栅的水平运动或斑点，在右侧ADN的情况下，斑点绕偏航轴顺时针移动（左侧ADN为逆时针）。相反方向的运动会抑制活动。空间敏感性在偏航平面上变化，同侧0度至40度之间有最大值，但同侧和对侧视野中80度范围内都会引发兴奋和抑制。ADN MNs对高达15 - 20赫兹的对比度频率有反应，在兴奋或抑制方向上光栅运动时，峰值约在2 - 4赫兹。对FN的电刺激主要引发向同侧的滚动。唯一持续由视觉刺激驱动的FN MN在同侧视野80度方位角时，被向下运动激发，被向上运动抑制。在对侧 - 80度时，视觉运动有相反的效果：向上是兴奋性的，向下是抑制性的。FN MN对对比度频率的调谐范围与ADN MNs相同，峰值敏感性约为4赫兹。关于已识别的视觉中间神经元和控制运动输出的平行通路，讨论了ADN和FN输入的功能组织。
