PRELIMINARY DATA FOR THE ELABORATION OF THE VISUAL CODE 



665 



a 



b 



Fig. 6. 



Contemporary recordings from two fibers of the optic nerve, one a continuously firing, on-off. 

 modulated fiber and one an off-fiber. The line under each registration shows the stimulus changes- 

 In a) it can be seen, that the initial slow decrease of the light intensity does not elicit an off- 

 response, whereas the following quicker light change provokes a big off-response though stimulus 

 duration was much shorter and the stimulus intensity lower. b) shows différent speeds of light 

 changes, which provoke on and off-responses. The stimulus was very strong white light, as lower 

 light intensities, which give strong responses in secondary and tertiary fibers, elicit only very 

 small responses in the fibers of the optic nerve. 



LITERATURE 



: Bernhard, C. G. 1966. Functional organization of the compound eye. Pergamon Press, 

 Oxford. 



Brmtenberg, V. 1970. Ordnung imd Orientierung der Elemente im Sehsystem der Fliege., 



Kybernetik 7: 235-242. 

 Collett, T. 1970. Centripetal and Centrifugal Visual Cells in the Medulla of the Insect 



Optic Lobe. J. Neurophysiol. 33 : 239-256. 

 Hamori, J. and G. A. Horridge. 1966. The lobster optic Lamina I. General organization. 



J. Cell Sci. 1 : 249-256. 



— 1966/). The lobster optic Lamina IL Types of Synapse. J. Cell Sci. 1: 257-270. 

 Mote, M. I. 1970a. Focal recording of responses evoked by light in the Lamina ganglio- 



naris of the Fly Sarcophaga bullata. J. exp. Zool. 175: 149-158. 



— 19706. Electrical correlates of neural superposition in the eye of the Fly Sarcophaga 



bullata. J. exp. Zool. 175: 159-168. 



Rev. Suisse de Zool., T. 78, 1971. 



43 



