The Experts below are selected from a list of 1401 Experts worldwide ranked by ideXlab platform
Diane C Gooding - One of the best experts on this subject based on the ideXlab platform.
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antisaccade task performance in questionnaire identified schizotypes
Schizophrenia Research, 1999Co-Authors: Diane C GoodingAbstract:Individuals who scored high on Perceptual Aberration–Magical Ideation Scales (Per–Mag; n=90), the Social Anhedonia Scale (SocAnh; n=39), and control participants (n=89) were administered Saccadic refixation (prosaccade) and Saccadic Suppression (antisaccade) tasks. Eye movements were scored in terms of error rates and latency. None of the groups differed in terms of their performance on the prosaccade task. Both the Per–Mag (p<0.01) and SocAnh (p<0.05) groups exceeded the controls in terms of mean antisaccade errors. The high-risk groups did not differ from each other. Eighteen of the Per–Mag individuals and 10 of the SocAnh individuals displayed deviant antisaccade performance. These findings are particularly interesting in light of suggestive evidence that antisaccade task deficits may serve as a marker of susceptibility to schizophrenia. It is hypothesized that the individuals who scored aberrantly on the Chapman scales and displayed antisaccade performance deficits are most likely to be at risk for the development of psychosis.
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antisaccade task performance in questionnaire identified schizotypes
Schizophrenia Research, 1999Co-Authors: Diane C GoodingAbstract:Abstract Individuals who scored high on Perceptual Aberration–Magical Ideation Scales (Per–Mag; n =90), the Social Anhedonia Scale (SocAnh; n =39), and control participants ( n =89) were administered Saccadic refixation (prosaccade) and Saccadic Suppression (antisaccade) tasks. Eye movements were scored in terms of error rates and latency. None of the groups differed in terms of their performance on the prosaccade task. Both the Per–Mag ( p p
Bruce Bridgeman - One of the best experts on this subject based on the ideXlab platform.
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different effects of eyelid blinks and target blanking on Saccadic Suppression of displacement
Attention Perception & Psychophysics, 2004Co-Authors: Heiner Deubel, Bruce Bridgeman, Werner X SchneiderAbstract:Displacements of visual stimuli during Saccadic eye movements are often not noticed. We have demonstrated that Saccadic Suppression of image displacement can be eliminated by blanking the stimulus for a short period during and after the saccade (Deubel, Schneider, & Bridgeman, 1996). Here we report an experiment in which target visibility was interrupted after the saccade, either by distal target blanking or by voluntary eyeblink. The data show that the effect of blinking is different from blanking; interruption of vision due to a blink did not enable subjects to detect target displacements any better than they had done in the no-blank condition. The results provide evidence for an extraretinal signal that distinguishes between endogenous and exogenous sources of temporary object disappearance after the saccade.
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an unbiased measure of the contributions of chroma and luminance to Saccadic Suppression of displacement
Experimental Brain Research, 2002Co-Authors: Sulekha Anand, Bruce BridgemanAbstract:Perception of image displacement is suppressed during Saccadic eye movements. We probed the source of Saccadic Suppression of displacement by testing whether it selectively affects chromatic- or luminance-based motion information. Human subjects viewed a stimulus in which chromatic and luminance cues provided conflicting information about displacement direction. Apparent motion occurred during either fixation or a 19.5° saccade. Subjects detected motion and discriminated displacement direction in each trial. They reported motion in over 90% of fixation trials and over 70% of saccade trials. During fixation, the probability of perceiving the direction carried by chromatic cues decreased as luminance contrast increased. During saccades, subjects tended to perceive the direction indicated by luminance cues when luminance contrast was high. However, when luminance contrast was low, subjects showed no preference for the chromatic- or luminance-based direction. Thus magnocellular channels are suppressed, while stimulation of parvocellular channels is below threshold, so that neither channel drives motion perception during saccades. These results confirm that magnocellular inhibition is the source of Saccadic Suppression.
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postSaccadic target blanking prevents Saccadic Suppression of image displacement
Vision Research, 1996Co-Authors: Heiner Deubel, Werner X Schneider, Bruce BridgemanAbstract:Abstract Displacement of a visual target during a Saccadic eye movement is normally detected only at a high threshold, implying that high-quality information about target position is not stored in the nervous system across the saccade. We show that blanking the target for 50–300 msec after a saccade restores sensitivity to the displacement. With blanking, subjects reliably detect displacements as small as 0.33 deg across 6 deg eye movements, with correspondingly steep psychophysical functions. Performance with blanking in a fixation control is inferior, evidence for a Saccadic enhancement of sensitivity to image displacement. If blanking is delayed so that the target is visible immediately after the saccade in its displaced position, performance declines to non-blanking levels. Blanking the target before the saccade, and restoring it during the saccade, yields a similar but weaker effect. We interpret these results with a model in which the visual system searches for the postSaccadic goal target within a restricted spatiotemporal window. If it is not found, the assumption of stationarity of the world is broken and the system makes use of other information such as extraretinal signals for calibrating location.
Richard J Krauzlis - One of the best experts on this subject based on the ideXlab platform.
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microSaccadic Suppression of visual bursts in the primate superior colliculus
The Journal of Neuroscience, 2010Co-Authors: Ziad M Hafed, Richard J KrauzlisAbstract:Saccadic Suppression, a behavioral phenomenon in which perceptual thresholds are elevated before, during, and after Saccadic eye movements, is an important mechanism for maintaining perceptual stability. However, even during fixation, the eyes never remain still, but undergo movements including microsaccades, drift, and tremor. The neural mechanisms for mediating perceptual stability in the face of these “fixational” movements are not fully understood. Here, we investigated one component of such mechanisms: a neural correlate of microSaccadic Suppression. We measured the size of short-latency, stimulus-induced visual bursts in superior colliculus neurons of adult, male rhesus macaques. We found that microsaccades caused ∼30% Suppression of the bursts. Suppression started ∼70 ms before microsaccade onset and ended ∼70 ms after microsaccade end, a time course similar to behavioral measures of this phenomenon in humans. We also identified a new behavioral effect of microSaccadic Suppression on Saccadic reaction times, even for continuously presented, suprathreshold visual stimuli. These results provide evidence that the superior colliculus is part of the mechanism for suppressing self-generated visual signals during microsaccades that might otherwise disrupt perceptual stability.
Werner X Schneider - One of the best experts on this subject based on the ideXlab platform.
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different effects of eyelid blinks and target blanking on Saccadic Suppression of displacement
Attention Perception & Psychophysics, 2004Co-Authors: Heiner Deubel, Bruce Bridgeman, Werner X SchneiderAbstract:Displacements of visual stimuli during Saccadic eye movements are often not noticed. We have demonstrated that Saccadic Suppression of image displacement can be eliminated by blanking the stimulus for a short period during and after the saccade (Deubel, Schneider, & Bridgeman, 1996). Here we report an experiment in which target visibility was interrupted after the saccade, either by distal target blanking or by voluntary eyeblink. The data show that the effect of blinking is different from blanking; interruption of vision due to a blink did not enable subjects to detect target displacements any better than they had done in the no-blank condition. The results provide evidence for an extraretinal signal that distinguishes between endogenous and exogenous sources of temporary object disappearance after the saccade.
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postSaccadic target blanking prevents Saccadic Suppression of image displacement
Vision Research, 1996Co-Authors: Heiner Deubel, Werner X Schneider, Bruce BridgemanAbstract:Abstract Displacement of a visual target during a Saccadic eye movement is normally detected only at a high threshold, implying that high-quality information about target position is not stored in the nervous system across the saccade. We show that blanking the target for 50–300 msec after a saccade restores sensitivity to the displacement. With blanking, subjects reliably detect displacements as small as 0.33 deg across 6 deg eye movements, with correspondingly steep psychophysical functions. Performance with blanking in a fixation control is inferior, evidence for a Saccadic enhancement of sensitivity to image displacement. If blanking is delayed so that the target is visible immediately after the saccade in its displaced position, performance declines to non-blanking levels. Blanking the target before the saccade, and restoring it during the saccade, yields a similar but weaker effect. We interpret these results with a model in which the visual system searches for the postSaccadic goal target within a restricted spatiotemporal window. If it is not found, the assumption of stationarity of the world is broken and the system makes use of other information such as extraretinal signals for calibrating location.
Julius J Zhu - One of the best experts on this subject based on the ideXlab platform.
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lack of visual Suppression in the rabbit lateral geniculate nucleus during blink reflex
Brain Research, 1997Co-Authors: Julius J ZhuAbstract:Stimulation of the supraorbital branch of the trigeminal nerve (SO) elicited eye blinks in the rabbit, but did not decrease the amplitude of visual cortical evoked potential from stimulation of the optic chiasm (OX). In addition, the SO stimulation neither induced an inhibitory postsynaptic potential (IPSP) in LGN cells, nor activated inhibitory interneurons in the thalamic reticular nucleus (TRN), which proved to mediate both recurrent inhibition and Saccadic Suppression in the dorsal lateral geniculate nucleus (LGN). All these indicate that there is no visual Suppression in the rabbit LGN during blink reflex.
