Saccadic facilitation by modulation of microsaccades in natural backgrounds

Sinn, Petra; Engbert, Ralf

doi:10.3758/s13414-011-0107-9

Cited by 10 publications

(10 citation statements)

References 16 publications

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“…Besides, we observed a significant modulation of the microsaccade rate (across conditions, see Figures 3B and 4A1, B1) during FP2a compared to FP2b although the visual background was identical during these two periods (the only difference being that subjects delivered their judgments at the end of FP2a). Sinn and Engbert (2011) reported a stronger decrease of the microsaccade rate after stimulus presentation when testing structured versus uniform backgrounds. Here, we tested structured backgrounds and observed significant variations of the microsaccade rate depending on whether static or dynamic noise was present in the background.…”

Section: Background Noise Discrimination Task and Microsaccadesmentioning

confidence: 95%

Microsaccades are modulated by both attentional demands of a visual discrimination task and background noise

et al. 2013

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Microsaccades are miniature saccades occurring once or twice per second during visual fixation. While microsaccades and saccades share similarities at the oculomotor level, the functional roles of microsaccades are still debated. In this study, we examined the hypothesis that the microsaccadic activity is affected by the type of noisy background during the execution of a particular discrimination task. Human subjects had to judge the orientation of a tilted stimulus embedded in static or dynamic backgrounds in a forced choice-task paradigm, as adapted from Rucci, Iovin, Poletti, and Santini (2007). Static backgrounds induced more microsaccades than dynamic ones only during the execution of the discrimination task. A directional bias of microsaccades, dictated by the stimulus orientation, was temporally coupled with this period of increased activity. Both microsaccade rates and orientations were comparable across background types after the response time although subjects maintained fixation until the end of the trial. This represents a background-specific modulation of the microsaccadic activity driven by attentional demands. The visual influence of microsaccades on discrimination performances was modeled at the retinal level for both types of backgrounds. A higher simulated microsaccadic activity was necessary for static backgrounds in order to achieve discrimination performance scores comparable to that of dynamic ones. Taken together, our experimental and theoretical findings further support the idea that microsaccades are under attentional control and represent an efficient sampling strategy allowing spatial information acquisition.

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Section: Background Noise Discrimination Task and Microsaccadesmentioning

confidence: 95%

Microsaccades are modulated by both attentional demands of a visual discrimination task and background noise

et al. 2013

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“…Second, the frequency of fixational saccades decreased gradually before stimulus appearance on overlap trials (Fig. A; Rolfs et al ., ; Pastukhov & Braun, ; Hafed et al ., ; Sinn & Engbert, ; Watanabe et al ., ).…”

Section: Resultsmentioning

confidence: 99%

“…We hypothesized that the frequency of fixational saccades decreases during the gap period, which in turn facilitates targeting saccade initiation because fixational saccades delay targeting saccade initiation (Rolfs et al ., ; Hafed & Krauzlis, ; Sinn & Engbert, ; Watanabe et al ., ). This prediction is consistent with the fact that neurons in the rostral superior colliculus (SC) that are involved in fixational saccade generation (Hafed et al ., ) decrease activity during the gap period (Dorris & Munoz, ; Dorris et al ., ; Everling et al ., ).…”

Section: Resultsmentioning

confidence: 99%

“…Fixational saccades delayed targeting saccade initiation (Table ), consistent with previous reports (Rolfs et al ., ; Hafed & Krauzlis, ; Sinn & Engbert, ; Watanabe et al ., ). More importantly, we found that fixational saccades prolonged the gap effect on targeting saccade reaction times (regression coefficients for interaction in Table ).…”

Section: Discussionmentioning

confidence: 99%

“…However, the above experimental techniques influence not only targeting saccades but also miniature eye movements that occur during fixation (Hafed & Clark, ; Engbert & Kliegl, ; Rolfs et al ., ). This is important to consider because fixational saccades, the largest miniature eye movements, including microsaccades, have significant impact on targeting saccades (Rolfs et al ., ; Hafed & Krauzlis, ; Sinn & Engbert, ; Watanabe et al ., ). Fixational saccades could delay targeting saccade initiation by the suppression of incoming visual signals (Zuber & Stark, ; Leopold & Logothetis, ; Hafed & Krauzlis, ) and/or competitive interactions between motor commands for fixational and targeting saccades (Munoz & Istvan, ; Trappenberg et al ., ; Rolfs & Ohl, ).…”

Section: Introductionmentioning

confidence: 99%

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Fixational saccades alter the gap effect

Watanabe

Matsuo

Zha

et al. 2014

Eur J of Neuroscience

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The reaction times of saccadic eye movements have been studied extensively as a probe for cognitive behavior controlled by large-scale cortical and subcortical neural networks. Recent studies have shown that the reaction times of targeting saccades toward peripheral visual stimuli are prolonged by fixational saccades, the largest miniature eye movements including microsaccades. We have shown previously that the frequency of fixational saccades is decreased by volitional action preparation controlled internally during the antisaccade paradigm (look away from a stimulus). Instead, here we examined whether fixational saccade modulation induced externally by sensory events could also account for targeting saccade facilitation by the same sensory events. When targeting saccades were facilitated by prior fixation stimulus disappearance (gap effect), fixational saccade occurrence was reduced, which could theoretically facilitate targeting saccades. However, such reduction was followed immediately by the rebound of fixational saccade occurrence in some subjects, which could eliminate potential benefits from the previous fixational saccade reduction. These results do not mean that fixational saccades were unrelated to the gap effect because they indeed altered that effect by delaying targeting saccade initiation on trials without the fixation gap more strongly than trials with it. Such changes might be attributed to the disruption of volitional saccade preparation because the frequency of fixational saccades observed in this study was associated with the ability of volitional control over antisaccade behavior. These results suggest that fixational saccades alter the gap effect on targeting saccade reaction times, presumably by disrupting volitional saccade commands.

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