Horridge G A, Marcelja L
Centre for Visual Sciences, Research School of Biological Sciences, Australian National University, Canberra.
Proc Biol Sci. 1992 Apr 22;248(1321):47-54. doi: 10.1098/rspb.1992.0041.
In a fly, butterfly, locust and dragonfly we examined the responses of a variety of directional motion-sensitive neurons which run from the brain down the ventral cord. The stimulus was a sinusoidally modulated moving pattern of regular stripes presented at a range of velocities in random order for either 0.1 s or 2.0 s. The response was measured as the total number of spikes to each stimulus. The neurons fall into two groups, 'fast' and 'slow'. The responses of the fast type rise progressively to a peak contrast frequency at 15-20 Hz for all four insects, and decline at higher contrast frequencies. The responses of slow neurons rise rapidly to a peak at 1-10 Hz and then decline more slowly across the range where the fast neurons are at their peak. The existence of two groups of neurons with overlapping response ranges to different velocities of the same pattern, presented in exactly the same way, provides the insect with a means of measuring angular velocity irrespective of contrast, spatial frequency or intensity. As an input mechanism it is proposed that there are two types of unit motion detector, fast and slow, the latter being the main input to the optomotor system. It is also argued that even these inputs are not sufficient to provide a mechanism for the whole repertoire of normal insect vision.
我们研究了苍蝇、蝴蝶、蝗虫和蜻蜓体内各种从大脑延伸至腹神经索的方向运动敏感神经元的反应。刺激物是一系列以随机顺序呈现的、具有不同速度的正弦调制的规则条纹移动图案，持续时间为0.1秒或2.0秒。反应以每个刺激引发的尖峰总数来衡量。这些神经元分为“快速”和“慢速”两组。对于所有这四种昆虫，快速型神经元的反应在15 - 20赫兹时逐渐上升至峰值对比频率，在更高的对比频率下则下降。慢速神经元的反应在1 - 10赫兹时迅速上升至峰值，然后在快速神经元处于峰值的频率范围内下降得更为缓慢。以完全相同的方式呈现的、对相同图案的不同速度具有重叠反应范围的两组神经元的存在，为昆虫提供了一种测量角速度的方法，而与对比度、空间频率或强度无关。作为一种输入机制，有人提出存在两种类型的单位运动探测器，即快速型和慢速型，后者是视动系统的主要输入。也有人认为，即使这些输入也不足以提供一种机制来实现正常昆虫视觉的全部功能。
