Saccade Automation

Abstract

The comparative analysis of basic saccade characteristics (interval, amplitude, and coefficient of asymmetry) has shown considerable similarities in adults and first-year babies. Distribution curves of intersaccadic intervals under different test conditions all have only one maximum in the range of about 0.4 s, and in all cases the most frequently met intersaccadic intervals (0.1 – 1.0) comprised comparable proportions of all (71.5% – 90.5%).

The concept of saccade automation was formulated on the basis of these data (Filin and Filina, 1989 Zhurnal Vysshei Nervnoi Deyatelnosti 29 603 – 607). In our opinion saccade automation is the basic law of saccadic activity, and all diversity of eye-movement activity takes place against the background of saccade automation. Microsaccades and macrosaccades, nystagmus, and rapid eye movements during sleep may be seen as special cases of saccade automation. Saccade automation is conditioned by the activity of brain structures with pacemaker function. Thus saccades are driven at one basic frequency, which is modulated by afferent influences from the retina of vestibular apparatus, proprioreceptors of eye and neck muscles, and efferent signals (forehead and occipital sections of cerebral cortex, cerebellum). At the same time, only one parameter is modulated at one particular moment, for example saccade amplitude in which case interval and orientation are given in a ready form.

Saccade automation has a great functional importance. It increases the scanned area tenfold, it provides compensation of defects in the sensors and the impellent eye apparatus and for the deletion of consecutive images, maintaining the continuity of visual perception. Moving the image on the retina increases the information of the visual channel.