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Summary. 1. Toads Bufo bufo (L.) prefer as prey "worm-like" objects with long axis orientation parallel to the movement direction rather than the same objects oriented "antiworm-like" with their long axis perpendicular to the movement direction.2. By means of statistical correlation methods with computer programs it was analyzed to what extent neurons from different regions of the visual pathway respond sensitively, selectively or specifically to moving configurational stimuli, such as worm-like and antiworm-like objects of equivalent sizes.3. Neurons with sensitivity to particular moving configurational stimuli were found in the retina (classes R2, R3, R4) and the retinal projection fields in the thalamic pretectal region (class TH3) and the optic tectum (class T5(1)).4. Neurons with selective responses to moving configurational stimulus objects, corresponding to the behavior, were found in a particular population of tectal neurons (class T5 (2)).5. No neurons were found with specific responses to a stimulus of a certain configuration.

Summary. 1. The activity of 59 neurons situated at different points along the visual pathway of the toadBufo bufo (L.) were investigated quantitatively by extracellular microelectrode recording methods. The activity was recorded in response to a variety of moving configurational stimuli which traversed the excitatory receptive fields of these neurons: Various sized squares and stripes of different length, oriented either in or perpendicular to the direction of movement, were used as visual stimuli. The stimuli were moved at constant visual angular velocity. The neuronal activities were evaluated by five different methods ( Fig. 1A-E). The electrode positions in the brain tissue for all neurons investigated were reconstructed histologically (Fig. 2 A-C).2. In the central layers of the optic rectum two statistically different neuronal populations were identified ( Fig. 3A and B). Neurons of one population, class T5 (1), were sensitive to the area of a moving stimulus and were activated mainly by configurational stimuli elongated in the direction of movement rather than by the extension of the same stimulus object perpendicular to the direction of movement (Fig. 5). Neurons of another population in the same layers of the optic tectum, class T 5 (2), were found to be activated by elongation of a configurational stimulus in the direction of movement, but inhibited by extension perpendicular to the direction of movement (Figs. 4 and 6).3. In the thalamic pretectal region neurons (class TH3) were recorded showing sensitivity to the area of a moving stimulus. They were activated mainly by configurational stimuli elongated perpendicular to the direction of movement rather than by extension in the direction of movement (Fig. 8).

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