Computational Modeling of Collicular Integration of Perceptual Responses and Attention in Microsaccades

Abstract

During visual fixation on a target object, our eyes are not motionless but generate slow fixational eye movements and microsaccades. Effects of visual attention have been observed in both microsaccade rates and spatial directions. Experimental results, however, range from early (Ͻ200 ms) to late (Ͼ600 ms) effects combined with cue-congruent as well as cue-incongruent microsaccade directions. On the basis of well characterized neural circuitry in superior colliculus, we construct a dynamical model of neural activation that is modulated by perceptual input and visual attention. Our results show that additive integration of low-level perceptual responses and visual attention can explain microsaccade rate and direction effects across a range of visual cueing tasks. These findings suggest that the patterns of microsaccade direction observed in experiments are compatible with a single dynamical mechanism. The basic principles of the model are highly relevant to the general problem of integration of low-level perception and top-down selective attention.

Microscopic Eye Movements Compensate for Nonhomogeneous Vision within the Fovea

“…These data provide an explanation for the previous observation of precisely directed microsaccades in high-acuity visuomotor tasks [30] and are consistent with recent findings highlighting the similarities between microsaccades and saccades in terms of the underlying neural substrate [31, 32], their impact on neural responses [33], and their associated perceptual consequences [34–36]. Furthermore, our results imply that fine spatial vision may be compromised when microsaccades are not precisely executed, raising the possibility for a causal link between the abnormal fixational eye movements and the reduced visual acuity that coexist in various disorders [37–44].…”

Microsaccades Are Coupled to Heartbeat

“…From the perspective of neural dynamics (Engbert et al, 2011), heartbeat drives slow fixational eye movements by oscillatory changes of the movement's potential that constrains the current focus of visual selective attention (Hafed and Clark, 2002;Engbert and Kliegl, 2003). Such a mechanism has been shown to modulate microsaccade rates (Engbert, 2012) and might be implemented in the superior colliculus. Indeed, the coupling of microsaccade statistics and visual attention is disrupted after suppression of activity in the superior colliculus .…”

Suppressive interactions underlying visually evoked fixational saccades

“…It was proposed that the microsaccadic/saccadic inhibition might reflect a fast, reflex-like response of the oculomotor system to sudden changes in the visual scene (Engbert, 2012; Reingold & Stampe, 2002), which might serve to facilitate the processing of new visual information (Rolfs et al, 2008a). The physiological implementation of microsaccadic/saccadic inhibition is a matter of debate (see Possible neural basis below; Engbert, 2006; Hafed, 2011; Hafed & Ignashchenkova, 2013; Reingold & Stampe, 2002; Rolfs et al, 2008a; Stampe & Reingold, 2002).…”