Abstract
Abstract: :
Purpose: To model the effects of microsaccades on the capacity of cones and cone–driven ganglion cells in the human fovea to detect and discriminate borders and lines. Methods: Typical human microsaccade patterns were applied to stationary achromatic borders and lines passed through the foveal line–spread function and projected onto the human foveal cone mosaic. The resulting moving retinal contrast patterns were convolved with the response kinetics of primate cones as reported by Schnapf et al. (1990), and the output of the cone–driven ganglion cells was calculated by the difference–of–gaussians receptive field model of Donner and Hemilä (1996). Results: Microsaccades may dramatically enhance sensitivity to edges and lines and especially help to distinguish two or several closely spaced lines from a single line. Conclusions: Being under neural control, the microsaccade patterns (forward–return) and velocities appear to be "tuned" to the spatio–temporal properties of foveal cones and ganglion cells. To our knowledge, the effects of microsaccades and other small (fixational) eye movements on these primary signals of the visual system have not previously received attention, although they set border conditions for performance at any subsequent stage.
Keywords: eye movements • photoreceptors: visual performance • discrimination