THE SPECTRAL RESPONSES OF MOTION SENSITIVE NEURONS OF DRAGONFLY
蜻蜒运动检测神经元的光谱反应

Self-motion detectors of the draonfly ventral cord have large fields that are sensitive to whole-field one way motion with little habituation to the motion. When testing with a flash of controlled intensity and wavelength, the self-motion neurons have a spectral sensitivity similar to that of photoreceptors with a peak in the green near 500nm, but when tested with a moving edge, they have a single peak near 560nm. When tested with a moving pattern on a background with self-motion neurons there is a value of brightness of the foreground so that it cannot be detected against background even for two difierent colours. They behave towards a pattern of two colours as if they are monochromatic, as know for motion perception measured behaviourally or from single neurons in other insects with colour vision.The object - motion neurons have an average spectral sensitivity curve which is rather flat from 380nm to 560nm For object- motion neurons the situation is quite different When the foreground and the background have different colours, there is no valve of the foreground brightness which gives a null response, however the value of the foreground brightness is adjusted But there is a value of the foreground brightness at which the responses of the object-motion neuron reach spontaneous level when the foreground colour and the background colour are the same. The optimum performance for seeing a coloured object appears when the background is green and the object is another colour, discrimination of the object is less effective when the object is green. This result suggests that limit motion detectors are colour coded and the green ones feed into the background system.