[Saccadic eye movements during sinusoidal rotational stimulation in rabbits in the postnatal period]

Electro-oculograms were recorded from rabbits of the 5th, 11th, 18th and 25th day of life as well as from adult animals by means of chronically implanted silver wire electrodes. The sinusoidal rotation of the fixed alert animals in the horizontal plane were carried out by frequencies of 0.05, 0.2, 0.5 and 1.0 Hz using amplitudes of 15 degrees, 22.5 degrees and 45 degrees (peak to peak: 30 degrees, 45 degrees and 90 degrees). The saccade-(Sc)-threshold as well as the Sc-frequency were determined and the phase angle between stimulus and eye movement was measured. The Sc-threshold depends on the stimulation amplitude and shows a longer postnatal development in small 15 degrees-amplitude stimulations than in more intensive ones. The Sc-frequency appears to be an age-, amplitude- and frequency-dependent parameter. It rises with advancing age and increasing stimulation amplitude, respectively. The number of Sc increases also with growing rotational frequency up to a maximum and decreases when using further rising frequencies. In contrast to eye movements without Sc, the phase angle is diminished in movements interrupted by Sc-reactions. This phenomenon as well as the decreasing phase angle with increasing rotational frequency occur in all age groups. Thus, the Sc cause a better temporal precision of vestibular-guided stabilization of the retinal image during the postnatal ontogenesis from the first time of their appearance onward.