Microsaccade

The term Mikrosakkade referred a quick, jerky eye target movement of the eye with a very small amplitude between 3 and 50 arcmin. The maximum speed of the movement is a linear function of the distance covered, and is about 8 degrees / sec at an amplitude of 5 minutes of arc, 80 degrees / sec at an amplitude of 50 minutes of angle. Microsaccades are in addition to the slow drifts and the micro- tremor of the so-called micro-movements, which are among the eye movements. They serve the regular realignment of the sight line on a fixation point, from which they differ by steadily drift movements to trigger no local adaptation.

Microsaccades usually occur 1-3 times per second, but their rate varies greatly between individuals. In naive subjects their amplitude is generally less than 30 minutes of arc (typically < 15 arcmin. This angle corresponds to about 80 microns, or 40 ~ displacement of the photoreceptors on the retina ). Currently, it is assumed that the generation of Microsaccades saccades and similar processes and common neuronal structures are based.

Physiological significance

The receptors of the retina react primarily to changes in lighting conditions. A constant light stimulus leads to vision loss through the receptor fatigue resulting in the impression of self- Grey (local adaptation). On a frozen head and paralysis of eye muscles, it causes temporary blindness. Micro-movements of the eye constantly shifting the light incident on the retina to different receptors and thus enable vision. Microsaccades appear here especially for peripheral vision ( vision in the corner of your eye ) to play a role, because the receptive fields of retinal cells are there too big to achieve stimulus changes due to other micro-movements.