Eingangs-ausgangsbeziehungen und modell eines drehreflexes der haustaubeColumbia livia

Abstract

Pigeons sitting on a turntable are exposed to horizontal $$\dot \phi $$ -ramp-and-hold stimuli (= $$\dot \phi $$ -RP-stimuli; $$\dot \phi $$ angular velocity) (Fig. 1). At the same time, the mean rateE(t) of impulses/0.1 s or 0.2 s ofM. abductor indicis, M. abductor pollicis orM. flexor pollicis is registered. If the rotation axis lies in or in front of the pigeon's head the muscles studied respond phasic-tonicly to an ipsilaterad $$\dot \phi $$ -RP-stimulus; and purely tonicly or also phasic-tonicly to a contralaterad $$\dot \phi $$ -RP-stimulus (Figs. 2C and 4). The heightE P of the tonic response component is independent from the direction of rotation and is only determined by the height $$\dot \phi _k $$ of the $$\dot \phi $$ -plateau (Fig. 2A). The heightE D of the phasic response component is dependent upon the rotation direction and is determined, at a given rotation direction, by $$\dot \phi _k $$ (Fig. 2A) and by the ramp slope $$\ddot \phi _0 $$ ( $$\ddot \phi $$ angular acceleration) (Fig. 3A). This and the dependence of the tonic component and, with some pigeons, also of the phasic component uponr (distance between pigeon and rotation axis) lead to the conclusion that the tonic component is caused by the centripetal accelerationb p , and the phasic component is caused by the angular acceleration $$\ddot \phi $$ and, with some pigeons, by the tangential accelerationb t. The influence of the acceleration components uponE D andE P is dependent upon the pigeon's position angle � relativ to the radiusvectorr (Figs. 4 and 5). The tonic component is the response to a quasi-pitch or a quasi-roll of the pigeon during steady rotation. This results from a comparison of the $$\dot \phi $$ -RP-responses of the pigeon in a radial or tangential position (Fig. 6A) to the pitch and roll responses (Fig. 6B). A model has been developed on the basis of the measured stimulus-response relations (Fig. 7). It contains three input channels (x -,u t- andu p-channel) with low-pass filters for the angular, tangential and centripetal acceleration. The channel gain depends upon �. The sum�(t) of all channel outputs is sent through a pure-time-delay element and finally through a half-wave rectifier with a threshold and an upper limitation. The transfer characteristics of the model agree rather well with those of the pigeon. The model can be interpreted in terms of neurophysiology.