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Denis Pelisson - One of the best experts on this subject based on the ideXlab platform.
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Sensory Processing of Motor Inaccuracy Depends on Previously Performed Movement and on Subsequent Motor Corrections: A Study of the Saccadic System
2013Co-Authors: Muriel Panouilleres, Christian Urquizar, Romeo Salemme, Denis PelissonAbstract:When goal-directed movements are inaccurate, two responses are generated by the brain: a fast motor correction toward the target and an adaptive motor recalibration developing progressively across subsequent trials. For the saccadic system, there is a clear dissociation between the fast motor correction (Corrective Saccade production) and the adaptive motor recalibration (primary Saccade modification). Error signals used to trigger Corrective Saccades and to induce adaptation are based on post-saccadic visual feedback. The goal of this study was to determine if similar or different error signals are involved in saccadic adaptation and in Corrective Saccade generation. Saccadic accuracy was experimentally altered by systematically displacing the visual target during motor execution. Post-saccadic error signals were studied by manipulating visual information in two ways. First, the duration of the displaced target after primary Saccade termination was set at 15, 50, 100 or 800 ms in different adaptation sessions. Second, in some sessions, the displaced target was followed by a visual mask that interfered with visual processing. Because they rely on different mechanisms, the adaptation of reactive Saccades and the adaptation of voluntary Saccades were both evaluated. We found that saccadic adaptation and Corrective Saccade production were both affected by the manipulations of post-saccadic visual information, but in different ways. This first finding suggests that different types of error signal processing are involved in the induction of these two motor corrections. Interestingly, voluntary Saccades required a longer duration of post-saccadic target presentation to reach the same amoun
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Schematic representation of the results.
2013Co-Authors: Muriel Panouilleres, Christian Urquizar, Romeo Salemme, Denis PelissonAbstract:This schema represents the differences in error signal processing between Saccade categories and between adaptation and Corrective Saccade generation. Each square indicates the minimal target duration leading to optimal adaptation or to optimal generation of Corrective Saccades, for both Saccade categories. The shading of the square represents the masking condition in which this target duration is required: grey square for the mask condition and black square for the no-mask condition (bicolour square when the same target duration is required in both masking conditions). The grey rectangles “Mask” symbolise the fact that when the mask is presented, a longer duration of stepped target is necessary to induce optimal adaptation and Corrective Saccade generation.
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sensory processing of motor inaccuracy depends on previously performed movement and on subsequent motor corrections a study of the saccadic system
PLOS ONE, 2011Co-Authors: Muriel Panouilleres, Christian Urquizar, Romeo Salemme, Denis PelissonAbstract:When goal-directed movements are inaccurate, two responses are generated by the brain: a fast motor correction toward the target and an adaptive motor recalibration developing progressively across subsequent trials. For the saccadic system, there is a clear dissociation between the fast motor correction (Corrective Saccade production) and the adaptive motor recalibration (primary Saccade modification). Error signals used to trigger Corrective Saccades and to induce adaptation are based on post-saccadic visual feedback. The goal of this study was to determine if similar or different error signals are involved in saccadic adaptation and in Corrective Saccade generation. Saccadic accuracy was experimentally altered by systematically displacing the visual target during motor execution. Post-saccadic error signals were studied by manipulating visual information in two ways. First, the duration of the displaced target after primary Saccade termination was set at 15, 50, 100 or 800 ms in different adaptation sessions. Second, in some sessions, the displaced target was followed by a visual mask that interfered with visual processing. Because they rely on different mechanisms, the adaptation of reactive Saccades and the adaptation of voluntary Saccades were both evaluated. We found that saccadic adaptation and Corrective Saccade production were both affected by the manipulations of post-saccadic visual information, but in different ways. This first finding suggests that different types of error signal processing are involved in the induction of these two motor corrections. Interestingly, voluntary Saccades required a longer duration of post-saccadic target presentation to reach the same amount of adaptation as reactive Saccades. Finally, the visual mask interfered with the production of Corrective Saccades only during the voluntary Saccades adaptation task. These last observations suggest that post-saccadic perception depends on the previously performed action and that the differences between Saccade categories of motor correction and adaptation occur at an early level of visual processing.
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Integration of visual information for Saccade production
Human Movement Science, 2011Co-Authors: Peggy Gerardin, Denis Pelisson, Valérie Gaveau, Claude PrablancAbstract:To foveate a visual target, subjects usually execute a primary hyp-ometric Saccade (S1) bringing the target in perifoveal vision, followed by a Corrective Saccade (S2) or by more than one S2. It is still debated to what extent these S2 are pre-programmed or dependent only on post-saccadic retinal error. To answer this question , we used a visually-triggered Saccade task in which target position and target visibility were manipulated. In one-third of the trials, the target was slightly displaced at S1 onset (so-called double step paradigm) and was maintained until the end of S1, until the start of the first S2 or until the end of the trial. Experiments took place in two visual environments: in the dark and in a dimly lit room with a visible random square background. The results showed that S2 were less accurate for shortest target durations. The duration of post-saccadic visual integration thus appears as the main factor responsible for Corrective Saccade accuracy. We also found that the visual context modulates primary Saccade accuracy , especially for the most hypometric subjects. These findings suggest that the saccadic system is sensitive to the visual properties of the environment and uses different strategies to maintain final gaze accuracy.
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Saccade control and eye-hand coordination in optic ataxia.
Neuropsychologia, 2007Co-Authors: Valérie Gaveau, Denis Pelisson, Christian Urquizar, Annabelle Blangero, Claude Prablanc, Alain Vighetto, Laure PisellaAbstract:The aim of this work was to investigate ocular control in patients with optic ataxia (OA). Following a lesion in the posterior parietal cortex (PPC), these patients exhibit a deficit for fast visuo-motor control of reach-to-grasp movements. Here, we assessed the fast visuo-motor control of Saccades as well as spontaneous eye-hand coordination in two bilateral OA patients and five neurologically intact controls in an ecological "look and point" paradigm. To test fast saccadic control, trials with unexpected target-jumps synchronised with Saccade onset were randomly intermixed with stationary target trials. Results confirmed that control subjects achieved visual capture (foveation) of the displaced targets with the same timing as stationary targets (fast saccadic control) and began their hand movement systematically at the end of the primary Saccade. In contrast, the two bilateral OA patients exhibited a delayed visual capture, especially of displaced targets, resulting from an impairment of fast saccadic control. They also exhibited a peculiar eye-hand coordination pattern, spontaneously delaying their hand movement onset until the execution of a final Corrective Saccade, which allowed target foveation. To test whether this pathological behaviour results from a delay in updating visual target location, we had subjects perform a second experiment in the same control subjects in which the target-jump was synchronised with Saccade offset. With less time for target location updating, the control subjects exhibited the same lack of fast saccadic control as the OA patients. We propose that OA corresponds to an impairment of fast updating of target location, therefore affecting both eye and hand movements.
Albert F. Fuchs - One of the best experts on this subject based on the ideXlab platform.
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Saccadic gain modification: visual error drives motor adaptation
Journal of neurophysiology, 1998Co-Authors: Josh Wallman, Albert F. FuchsAbstract:The brain maintains the accuracy of saccadic eye movements by adjusting saccadic amplitude relative to the target distance (i.e., Saccade gain) on the basis of the performance of recent Saccades. If an experimenter surreptitiously moves the target backward during each Saccade, thereby causing the eyes to land beyond their targets, Saccades undergo a gradual gain reduction. The error signal driving this conventional saccadic gain adaptation could be either visual (the postsaccadic distance of the target from the fovea) or motoric (the direction and size of the Corrective Saccade that brings the eye onto the back-stepped target). Similarly, the adaptation itself might be a motor adjustment (change in the size of Saccade for a given perceived target distance) or a visual remapping (change in the perceived target distance). We studied these possibilities in experiments both with rhesus macaques and with humans. To test whether the error signal is motoric, we used a paradigm devised by Heiner Deubel. The Deubel paradigm differed from the conventional adaptation paradigm in that the backward step that occurred during the Saccade was brief, and the target then returned to its original displaced location. This ploy replaced most of the usual backward Corrective Saccades with forward ones. Nevertheless, saccadic gain gradually decreased over hundreds of trials. Therefore, we conclude that the direction of saccadic gain adaptation is not determined by the direction of Corrective Saccades. To test whether gain adaptation is a manifestation of a static visual remapping, we decreased the gain of 10 degrees horizontal Saccades by conventional adaptation and then tested the gain to targets appearing at retinal locations unused during adaptation. To make the target appear in such "virgin territory," we had it jump first vertically and then 10 degrees horizontally; both jumps were completed and the target spot extinguished before Saccades were made sequentially to the remembered target locations. Conventional adaptation decreased the gain of the second, horizontal Saccade even though the target was in a nonadapted retinal location. In contrast, the horizontal component of oblique Saccades made directly to the same virgin location showed much less gain decrease, suggesting that the adaptation is specific to Saccade direction rather than to target location. Thus visual remapping cannot account for the entire reduction of saccadic gain. We conclude that saccadic gain adaptation involves an error signal that is primarily visual, not motor, but that the adaptation itself is primarily motor, not visual.
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role of the caudal fastigial nucleus in Saccade generation ii effects of muscimol inactivation
Journal of Neurophysiology, 1993Co-Authors: Farrel R. Robinson, A. Straube, Albert F. FuchsAbstract:1. We studied the effect of temporarily inhibiting neurons in the caudal fastigial nucleus in two rhesus macaques trained to make Saccades to jumping targets. We placed injections of the gamma-aminobutyric acid (GABA) agonist muscimol unilaterally or bilaterally at sites in the caudal fastigial nucleus where we had recorded Saccade-related neurons a few minutes earlier. 2. Unilateral injections (n = 9) made horizontal Saccades to the injected side hypermetric and those to the other side hypometric (mean gain of 1.37 and 0.61, respectively, for 10 degrees target steps, and 1.26 and 0.81 for 20 degrees target steps; normal Saccade gain was 0.96). Saccades to vertical targets showed a small but significant hypermetria and curved strongly toward the side of the injection. The trajectories and end points of all targeted Saccades were more variable than normal. 3. After unilateral injections, centripetal Saccades were slightly larger than centrifugal Saccades (mean gains for ipsilateral Saccades were 1.42 and 1.31, respectively, for 10 degrees target steps, and 1.37 and 1.15 for 20 degrees target steps). 4. Unilateral injections increased the average acceleration of ipsilateral Saccades and decreased the acceleration of contralateral Saccades. Injections decreased both the acceleration and deceleration of vertical Saccades. 5. After dysmetric Saccades, monkeys acquired the target with an abnormally high number of hypometric Corrective Saccades. Injection increased the average number of Corrective Saccades from 0.6 to 2.1 after 10 degrees horizontal target steps and from 0.8 to 2.1 after 20 degrees steps. The size of each successive Corrective Saccade in a series decreased, and the latency from the previous Corrective Saccade increased. 6. Bilateral injections (n = 2) of muscimol, in which we injected first into the left caudal fastigial nucleus and then, within 30 min, into the right, made all Saccades hypermetric (mean gain for 10 degrees right, left, up, and down Saccades was 1.18, 1.49, 1.43, and 1.10, respectively). Paradoxically, bilateral injection decreased both Saccade acceleration and deceleration. Saccade trajectories and end points were more variable than normal. 7. To account for the effects of our injections, we propose that the activity of caudal fastigial neurons on one side normally helps to decelerate ipsilateral Saccades and helps to accelerate contralateral Saccades by influencing the feedback loop of the Saccade burst generator in the brain stem. Without caudal fastigial activity the brain stem burst generator produces hypermetric, variable Saccades. We therefore also propose that the influence of caudal fastigial neurons on the burst generator makes Saccades more consistent and accurate.(ABSTRACT TRUNCATED AT 400 WORDS)
Christian Urquizar - One of the best experts on this subject based on the ideXlab platform.
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Sensory Processing of Motor Inaccuracy Depends on Previously Performed Movement and on Subsequent Motor Corrections: A Study of the Saccadic System
2013Co-Authors: Muriel Panouilleres, Christian Urquizar, Romeo Salemme, Denis PelissonAbstract:When goal-directed movements are inaccurate, two responses are generated by the brain: a fast motor correction toward the target and an adaptive motor recalibration developing progressively across subsequent trials. For the saccadic system, there is a clear dissociation between the fast motor correction (Corrective Saccade production) and the adaptive motor recalibration (primary Saccade modification). Error signals used to trigger Corrective Saccades and to induce adaptation are based on post-saccadic visual feedback. The goal of this study was to determine if similar or different error signals are involved in saccadic adaptation and in Corrective Saccade generation. Saccadic accuracy was experimentally altered by systematically displacing the visual target during motor execution. Post-saccadic error signals were studied by manipulating visual information in two ways. First, the duration of the displaced target after primary Saccade termination was set at 15, 50, 100 or 800 ms in different adaptation sessions. Second, in some sessions, the displaced target was followed by a visual mask that interfered with visual processing. Because they rely on different mechanisms, the adaptation of reactive Saccades and the adaptation of voluntary Saccades were both evaluated. We found that saccadic adaptation and Corrective Saccade production were both affected by the manipulations of post-saccadic visual information, but in different ways. This first finding suggests that different types of error signal processing are involved in the induction of these two motor corrections. Interestingly, voluntary Saccades required a longer duration of post-saccadic target presentation to reach the same amoun
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Schematic representation of the results.
2013Co-Authors: Muriel Panouilleres, Christian Urquizar, Romeo Salemme, Denis PelissonAbstract:This schema represents the differences in error signal processing between Saccade categories and between adaptation and Corrective Saccade generation. Each square indicates the minimal target duration leading to optimal adaptation or to optimal generation of Corrective Saccades, for both Saccade categories. The shading of the square represents the masking condition in which this target duration is required: grey square for the mask condition and black square for the no-mask condition (bicolour square when the same target duration is required in both masking conditions). The grey rectangles “Mask” symbolise the fact that when the mask is presented, a longer duration of stepped target is necessary to induce optimal adaptation and Corrective Saccade generation.
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sensory processing of motor inaccuracy depends on previously performed movement and on subsequent motor corrections a study of the saccadic system
PLOS ONE, 2011Co-Authors: Muriel Panouilleres, Christian Urquizar, Romeo Salemme, Denis PelissonAbstract:When goal-directed movements are inaccurate, two responses are generated by the brain: a fast motor correction toward the target and an adaptive motor recalibration developing progressively across subsequent trials. For the saccadic system, there is a clear dissociation between the fast motor correction (Corrective Saccade production) and the adaptive motor recalibration (primary Saccade modification). Error signals used to trigger Corrective Saccades and to induce adaptation are based on post-saccadic visual feedback. The goal of this study was to determine if similar or different error signals are involved in saccadic adaptation and in Corrective Saccade generation. Saccadic accuracy was experimentally altered by systematically displacing the visual target during motor execution. Post-saccadic error signals were studied by manipulating visual information in two ways. First, the duration of the displaced target after primary Saccade termination was set at 15, 50, 100 or 800 ms in different adaptation sessions. Second, in some sessions, the displaced target was followed by a visual mask that interfered with visual processing. Because they rely on different mechanisms, the adaptation of reactive Saccades and the adaptation of voluntary Saccades were both evaluated. We found that saccadic adaptation and Corrective Saccade production were both affected by the manipulations of post-saccadic visual information, but in different ways. This first finding suggests that different types of error signal processing are involved in the induction of these two motor corrections. Interestingly, voluntary Saccades required a longer duration of post-saccadic target presentation to reach the same amount of adaptation as reactive Saccades. Finally, the visual mask interfered with the production of Corrective Saccades only during the voluntary Saccades adaptation task. These last observations suggest that post-saccadic perception depends on the previously performed action and that the differences between Saccade categories of motor correction and adaptation occur at an early level of visual processing.
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Saccade control and eye-hand coordination in optic ataxia.
Neuropsychologia, 2007Co-Authors: Valérie Gaveau, Denis Pelisson, Christian Urquizar, Annabelle Blangero, Claude Prablanc, Alain Vighetto, Laure PisellaAbstract:The aim of this work was to investigate ocular control in patients with optic ataxia (OA). Following a lesion in the posterior parietal cortex (PPC), these patients exhibit a deficit for fast visuo-motor control of reach-to-grasp movements. Here, we assessed the fast visuo-motor control of Saccades as well as spontaneous eye-hand coordination in two bilateral OA patients and five neurologically intact controls in an ecological "look and point" paradigm. To test fast saccadic control, trials with unexpected target-jumps synchronised with Saccade onset were randomly intermixed with stationary target trials. Results confirmed that control subjects achieved visual capture (foveation) of the displaced targets with the same timing as stationary targets (fast saccadic control) and began their hand movement systematically at the end of the primary Saccade. In contrast, the two bilateral OA patients exhibited a delayed visual capture, especially of displaced targets, resulting from an impairment of fast saccadic control. They also exhibited a peculiar eye-hand coordination pattern, spontaneously delaying their hand movement onset until the execution of a final Corrective Saccade, which allowed target foveation. To test whether this pathological behaviour results from a delay in updating visual target location, we had subjects perform a second experiment in the same control subjects in which the target-jump was synchronised with Saccade offset. With less time for target location updating, the control subjects exhibited the same lack of fast saccadic control as the OA patients. We propose that OA corresponds to an impairment of fast updating of target location, therefore affecting both eye and hand movements.
Muriel Panouilleres - One of the best experts on this subject based on the ideXlab platform.
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Sensory Processing of Motor Inaccuracy Depends on Previously Performed Movement and on Subsequent Motor Corrections: A Study of the Saccadic System
2013Co-Authors: Muriel Panouilleres, Christian Urquizar, Romeo Salemme, Denis PelissonAbstract:When goal-directed movements are inaccurate, two responses are generated by the brain: a fast motor correction toward the target and an adaptive motor recalibration developing progressively across subsequent trials. For the saccadic system, there is a clear dissociation between the fast motor correction (Corrective Saccade production) and the adaptive motor recalibration (primary Saccade modification). Error signals used to trigger Corrective Saccades and to induce adaptation are based on post-saccadic visual feedback. The goal of this study was to determine if similar or different error signals are involved in saccadic adaptation and in Corrective Saccade generation. Saccadic accuracy was experimentally altered by systematically displacing the visual target during motor execution. Post-saccadic error signals were studied by manipulating visual information in two ways. First, the duration of the displaced target after primary Saccade termination was set at 15, 50, 100 or 800 ms in different adaptation sessions. Second, in some sessions, the displaced target was followed by a visual mask that interfered with visual processing. Because they rely on different mechanisms, the adaptation of reactive Saccades and the adaptation of voluntary Saccades were both evaluated. We found that saccadic adaptation and Corrective Saccade production were both affected by the manipulations of post-saccadic visual information, but in different ways. This first finding suggests that different types of error signal processing are involved in the induction of these two motor corrections. Interestingly, voluntary Saccades required a longer duration of post-saccadic target presentation to reach the same amoun
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Schematic representation of the results.
2013Co-Authors: Muriel Panouilleres, Christian Urquizar, Romeo Salemme, Denis PelissonAbstract:This schema represents the differences in error signal processing between Saccade categories and between adaptation and Corrective Saccade generation. Each square indicates the minimal target duration leading to optimal adaptation or to optimal generation of Corrective Saccades, for both Saccade categories. The shading of the square represents the masking condition in which this target duration is required: grey square for the mask condition and black square for the no-mask condition (bicolour square when the same target duration is required in both masking conditions). The grey rectangles “Mask” symbolise the fact that when the mask is presented, a longer duration of stepped target is necessary to induce optimal adaptation and Corrective Saccade generation.
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sensory processing of motor inaccuracy depends on previously performed movement and on subsequent motor corrections a study of the saccadic system
PLOS ONE, 2011Co-Authors: Muriel Panouilleres, Christian Urquizar, Romeo Salemme, Denis PelissonAbstract:When goal-directed movements are inaccurate, two responses are generated by the brain: a fast motor correction toward the target and an adaptive motor recalibration developing progressively across subsequent trials. For the saccadic system, there is a clear dissociation between the fast motor correction (Corrective Saccade production) and the adaptive motor recalibration (primary Saccade modification). Error signals used to trigger Corrective Saccades and to induce adaptation are based on post-saccadic visual feedback. The goal of this study was to determine if similar or different error signals are involved in saccadic adaptation and in Corrective Saccade generation. Saccadic accuracy was experimentally altered by systematically displacing the visual target during motor execution. Post-saccadic error signals were studied by manipulating visual information in two ways. First, the duration of the displaced target after primary Saccade termination was set at 15, 50, 100 or 800 ms in different adaptation sessions. Second, in some sessions, the displaced target was followed by a visual mask that interfered with visual processing. Because they rely on different mechanisms, the adaptation of reactive Saccades and the adaptation of voluntary Saccades were both evaluated. We found that saccadic adaptation and Corrective Saccade production were both affected by the manipulations of post-saccadic visual information, but in different ways. This first finding suggests that different types of error signal processing are involved in the induction of these two motor corrections. Interestingly, voluntary Saccades required a longer duration of post-saccadic target presentation to reach the same amount of adaptation as reactive Saccades. Finally, the visual mask interfered with the production of Corrective Saccades only during the voluntary Saccades adaptation task. These last observations suggest that post-saccadic perception depends on the previously performed action and that the differences between Saccade categories of motor correction and adaptation occur at an early level of visual processing.
Mark Shelhamer - One of the best experts on this subject based on the ideXlab platform.
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Behavioral analysis of predictive Saccade tracking as studied by countermanding
Experimental Brain Research, 2007Co-Authors: Wilsaan M. Joiner, Jung-eun Lee, Mark ShelhamerAbstract:The ability to make predictive saccadic eye movements is dependent on neural signals that anticipate the onset of a visual target. We used a novel paradigm—based on the Saccade-countermanding task—as a tool to investigate rhythm Saccade pacing and to provide information on the mechanisms of predictive timing. In particular, we examined the ability of normal subjects to stop a sequence of periodically paced eye movements when cued by a stop signal that was presented at different times with respect to the last target of the sequence (stop signal delay, SSD). The timing of the stop signal affected the ability to stop the saccadic sequence (make a Saccade to a central target rather than to the peripheral alternating targets) in different ways, depending on the preceding tracking behavior. For the same SSD, subjects cancelled fewer trials during predictive tracking (promoted by tracking targets alternating at a fast pacing rate, 1.0 Hz) than during reactive tracking (tracking alternating targets at a low pacing rate, 0.2 Hz). In addition, on non-canceled trials, there was an increase in the delay of the Corrective Saccade to the central target with increasing SSD for pacing at 0.2 Hz, but the timing of the Corrective Saccade remained near constant for 1.0 Hz pacing. In examining the timing between movements, we estimate that the repetitive GO process that drives the Saccades during predictive tracking begins earlier and has a shorter duration than the repetitive GO process during reactive tracking. These behavioral results provide further insight into the initiation process of predictive responses. In particular, the reduced reaction time and the corresponding short duration of the predictive process may result from a faster accumulation of neuronal discharge to a relatively fixed threshold.
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Adaptability and variability in the oculomotor system
Computational Neuroscience, 1997Co-Authors: David F. Scollan, Beau K. Nakamoto, Mark ShelhamerAbstract:We have been investigating the adaptive capabilities of a simple oculomotor system: saccadic eye movements. Saccades are rapid eye movements that take the line of gaze from one point to another very quickly, as when reading. Saccades are highly ballistic — once a Saccade to a visual target has been programmed, the eyes will go to that target (or very nearly so) even if the target subsequently changes position.1 A further Corrective Saccade must then be made to bring the eyes to the target.
