NEUROCOMPUTATION OF VISUAL RELATIVE MOTION INFORMATION

In this paper the neurocomputation of figure-ground relative motion information in thevisual system of the fly have been investigated in great detail by a combination of quanti-tative behavioural experiments and computational model simulations. Only torque responsesabout the vertical axis of the tethered flying flies (Musca domestica) were determined inthe behavioural experiment. The main results of behavioural experiments are: (i) The dynam-ics of the torque responses depends not only on the phase relationship between figure andbackground motion but also on the oscillation frequency of the figure and ground. (ii) Inall the phase relations tested, the time courses are a characteristic fingerprint of the partic-ular phase relationship. (iii) The variation of the amplitude of the response peaks is an espe-cially sensitive indicator for the variability of figure--ground discrimination behaviour. The main results of computer simulations are: (i) The 'computer fly', the networkmodel of both the SF-system and the LF--system with a two-dimensional array of elementarymovement detectors (EMDs) as the input layer have proved to be sufficient so far to ac-count for the main characteristics of the torque responses of the fly during stimulation withrelative motion under different conditions. (ii) The computer simulations fit the correspond-ing experimental data sufficiently well with respect to their characteristic features underdifferent stimulus conditions. (iii) The time course in computer simulation depends criticallyon the parameters n, q, T and k. The behavioural experimental results together with the computational model simulationscast a new light on an important problem: the strategies underlying the extraction of rela-tive motion information at the level of neural network.

In this paper the neurocomputation of figure-ground relative motion information in thevisual system of the fly have been investigated in great detail by a combination of quanti-tative behavioural experiments and computational model simulations. Only torque responsesabout the vertical axis of the tethered flying flies (Musca domestica) were determined inthe behavioural experiment. The main results of behavioural experiments are: (i) The dynam-ics of the torque responses depends not only on the phase relationship between figure andbackground motion but also on the oscillation frequency of the figure and ground. (ii) Inall the phase relations tested, the time courses are a characteristic fingerprint of the partic-ular phase relationship. (iii) The variation of the amplitude of the response peaks is an espe-cially sensitive indicator for the variability of figure--ground discrimination behaviour. The main results of computer simulations are: (i) The "computer fly", the networkmodel of both the SF-system