Characteristics of ?anti? saccades in man

Fischer, Burkhart; Weber, Heike

doi:10.1007/bf00228257

Cited by 231 publications

(97 citation statements)

References 27 publications

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“…based on proposal (1) of the visuomotor hypothesis is that express saccades shouid only be possible if a suddenly appearing stimulus serves both as the cue when to move and where to move. Some support for this has already been reported: express saccades do not appear if the cue when to move is an event other than the target's onset (Boch & Fischer, 1986); neither do they appear if a visual stimulus cues when to move, but the saccade is required to go away from it (Fischer & Weber, 1992).…”

Section: Implications Of the Visuomotor Hypothesismentioning

confidence: 76%

Express saccades elicited during visual scan in the monkey

Sommer

1994

Vision Research

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Monkeys trained to saccade to visual targets can develop separate "express" and "regular" modes in their distribution of saccadic latencies. The purpose of this study was to determine whether this occurs under more natural viewing conditions, when targets are suddenly presented in a structured visual field during visual scan. It was found that scanning saccades stopped appearing 60 msec after a target's onset, and subsequent saccades, which were directed toward the suddenly appearing target, had a bimodal distribution of latencies. Express saccades were more likely to occur as the target was presented later in a fixation. Regular mode saccades were more likely to occur with longer target durations. Scanning saccades made to stimuli of the structured visual field always had unimodal inter-saccadic interval distributions. All these effects were apparent after only 2-3 days of training. These findings, taken together with recent physiological results, suggest that the visuomotor cells of the superior collculus mediate latency bimodality.

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Section: Implications Of the Visuomotor Hypothesismentioning

confidence: 76%

Express saccades elicited during visual scan in the monkey

Sommer

1994

Vision Research

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“…Our findings of increased congruity costs can be considered in relation to other tasks in which a stimulus can instruct more than one response. In the prosaccade/ antisaccade paradigm (Fischer and Weber, 1992), subjects make saccades either towards or away from a visual target. Response times are slower in the antisaccade condition.…”

Section: Discussionmentioning

confidence: 99%

Effects of the NMDA Antagonist Ketamine on Task-Switching Performance: Evidence for Specific Impairments of Executive Control

Stoet

Snyder

2005

Neuropsychopharmacol

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In humans, the effects of subanesthetic doses of ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, substantially impair executive control functions. Here, we consider whether ketamine exposure can provide an animal model for the effects of ketamine on executive control. Two monkeys (Macaca mulatta) performed a cued task-switching paradigm. We studied their behavior before and after a range of ketamine doses. We found that ketamine slowed overall performance and decreased overall accuracy, strongly impaired the capacity to ignore task-irrelevant information and, to a lesser degree, decreased accuracy when a task switch was required. This pattern of results is very similar to that found in studies of schizophrenic patients performing task-switching paradigms or the Stroop task. We conclude that ketamine in monkeys provides a good animal model for exploring the relationship between the glutamate system, executive control, and the symptoms of schizophrenia.

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“…For example, the issue of whether a gap effect occurs for antisaccades (e.g., Fischer & Weber, 1992;Reuter-Lorenz et aI., 1991) can be approached with this framework in mind. Instead of asking whether a gap effect occurs for antisaccades, one might ask under what stimulus conditions a gap effect would occur for antisaccades.…”

Section: Discussionmentioning

confidence: 99%

Fixation disengagement and eye-movement latency

Tam

Ono

1994

Perception & Psychophysics

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We examined eye-movement latencies to a target that-appeared during visual fixation of a stationary stimulus, a moving stimulus, or an extrafoveal stimulus, The stimulus at fixation was turned off either before target onset (gap condition) or after target onset (overlap condition), Consistent with previous research, saccadic latencies were shorter in gap conditions than they were in overlap conditions (the gap effect). In Experiment 1, a gap effect was observed for vergence eye movements.. In Experiment 2, a gap effect was observed for saccades directed at a target that appeared during visual pursuit of a moving stimulus. In Experiment 3, a gap effect was observed for saccades directed at a target that appeared during extrafoveal fixation. The present results extend reports of the gap effect for saccadic shifts during visual fixation to (a) vergence shifts during visual fixation, (b) saccadic shifts during smooth visual pursuit, and (c) saccadic shifts during extrafoveal fixation. The present findings are discussed with respect to the incompatible goals of fixation-locking and fixation-shifting oculomotor responses.Saccadic latency to the onset of a target has been shown to depend on the temporal interval between target onset and the termination ofthe stimulus at fixation (e.g., Becker, 1972;Cohen & Ross, 1977;Iwasaki, 1990;Mayfrank, Mobashery, Kimmig, & Fischer, 1986; Reulen, 1984 Ross, 1981Ross, , 1983Saslow, 1967). Latencies are shorter when the stimulus at fixation is extinguished before target onset (gap condition) than they are when it is extinguished after target onset (overlap condition). This effect of stimulus offset on saccadic latencies is referred to as the gap effect. The effect is important in research on oculomotor behavior because of its relevance to processes involved in the preparation of eye movements. The goal of the present study was to extend the domain of study of the gap effect by investigating latencies of vergence eye movements and by examining latencies of saccadic eye movements while the eyes were pursuing a moving stimulus or fixating an extrafoveal stimulus.Recent studies of the gap effect have concentrated on the role of attentional processes, assuming that the gap

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Characteristics of ?anti? saccades in man

Cited by 231 publications

References 27 publications

Express saccades elicited during visual scan in the monkey

Express saccades elicited during visual scan in the monkey

Effects of the NMDA Antagonist Ketamine on Task-Switching Performance: Evidence for Specific Impairments of Executive Control

Fixation disengagement and eye-movement latency

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