6533b833fe1ef96bd129b580

RESEARCH PRODUCT

Neurobiologie und System-Theorie eines visuellen Muster-Erkennungsmechanismus bei Kröten

subject

description

Quantitative behavioral experiments have shown that the toad uses mainly two types of gestalt information in prey/enemy discrimination: pattern extension in the direction of movement promotes, in general, the signal value prey, while extension perpendicular to the direction of movement promotes that of enemy. Registrations from single fibers and single cells at different stages on the visual path showed that the object extension perpendicular to the direction of movement is chiefly analysed by means of the retinal and thalamus pretectal nerve nets, whereas the extension in the direction of movement is analysed mostly by certain tectal nerve nets. Further neurobiological findings indicated that the prey/enemy discrimination is the result of subtractive interaction between the tectal and thalamus pretectal nerve nets. The system answers given by the retina, the retina-pretectum and the retinatectum to the input patterns used in the neurobiological experiments were determined for relevant space and time parameters on the basis of two dimensional neuron network models. The experimental results agree well with the theoretical ones. If the subtractive interaction between the model networks hypothesized from the neurophysiological results is applied, the resulting system answer describes the behavioral findings very well. So it is shown that the networks investigated would suffice in principle for the behavioral interpretations of the key stimulus prey/enemy — so far as these are known.