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1
Krock, Rebecca M., and Tirin Moore. "Visual sensitivity of frontal eye field neurons during the preparation of saccadic eye movements." Journal of Neurophysiology 116, no. 6 (December 1, 2016): 2882–91. http://dx.doi.org/10.1152/jn.01140.2015.
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Primate vision is continuously disrupted by saccadic eye movements, and yet this disruption goes unperceived. One mechanism thought to reduce perception of this self-generated movement is saccadic suppression, a global loss of visual sensitivity just before, during, and after saccadic eye movements. The frontal eye field (FEF) is a candidate source of neural correlates of saccadic suppression previously observed in visual cortex, because it contributes to the generation of visually guided saccades and modulates visual cortical responses. However, whether the FEF exhibits a perisaccadic reduction in visual sensitivity that could be transmitted to visual cortex is unknown. To determine whether the FEF exhibits a signature of saccadic suppression, we recorded the visual responses of FEF neurons to brief, full-field visual probe stimuli presented during fixation and before onset of saccades directed away from the receptive field in rhesus macaques ( Macaca mulatta). We measured visual sensitivity during both epochs and found that it declines before saccade onset. Visual sensitivity was significantly reduced in visual but not visuomotor neurons. This reduced sensitivity was also present in visual neurons with no movement-related modulation during visually guided saccades and thus occurred independently from movement-related activity. Across the population of visual neurons, sensitivity began declining ∼80 ms before saccade onset. We also observed a similar presaccadic reduction in sensitivity to isoluminant, chromatic stimuli. Our results demonstrate that the signaling of visual information by FEF neurons is reduced during saccade preparation, and thus these neurons exhibit a signature of saccadic suppression.
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Hogendoorn, Hinze. "Voluntary Saccadic Eye Movements Ride the Attentional Rhythm." Journal of Cognitive Neuroscience 28, no. 10 (October 2016): 1625–35. http://dx.doi.org/10.1162/jocn_a_00986.
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Visual perception seems continuous, but recent evidence suggests that the underlying perceptual mechanisms are in fact periodic—particularly visual attention. Because visual attention is closely linked to the preparation of saccadic eye movements, the question arises how periodic attentional processes interact with the preparation and execution of voluntary saccades. In two experiments, human observers made voluntary saccades between two placeholders, monitoring each one for the presentation of a threshold-level target. Detection performance was evaluated as a function of latency with respect to saccade landing. The time course of detection performance revealed oscillations at around 4 Hz both before the saccade at the saccade origin and after the saccade at the saccade destination. Furthermore, oscillations before and after the saccade were in phase, meaning that the saccade did not disrupt or reset the ongoing attentional rhythm. Instead, it seems that voluntary saccades are executed as part of an ongoing attentional rhythm, with the eyes in flight during the troughs of the attentional wave. This finding for the first time demonstrates that periodic attentional mechanisms affect not only perception but also overt motor behavior.
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Seirafi, Mehrdad, Peter De Weerd, and Beatrice de Gelder. "Suppression of Face Perception during Saccadic Eye Movements." Journal of Ophthalmology 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/384510.
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Lack of awareness of a stimulus briefly presented during saccadic eye movement is known as saccadic omission. Studying the reduced visibility of visual stimuli around the time of saccade—known as saccadic suppression—is a key step to investigate saccadic omission. To date, almost all studies have been focused on the reduced visibility of simple stimuli such as flashes and bars. The extension of the results from simple stimuli to more complex objects has been neglected. In two experimental tasks, we measured the subjective and objective awareness of a briefly presented face stimuli during saccadic eye movement. In the first task, we measured the subjective awareness of the visual stimuli and showed that in most of the trials there is no conscious awareness of the faces. In the second task, we measured objective sensitivity in a two-alternative forced choice (2AFC) face detection task, which demonstrated chance-level performance. Here, we provide the first evidence of complete suppression of complex visual stimuli during the saccadic eye movement.
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Ibbotson, Michael, and Bart Krekelberg. "Visual perception and saccadic eye movements." Current Opinion in Neurobiology 21, no. 4 (August 2011): 553–58. http://dx.doi.org/10.1016/j.conb.2011.05.012.
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Prime, Steven L., Michael Vesia, and J. Douglas Crawford. "Cortical mechanisms for trans-saccadic memory and integration of multiple object features." Philosophical Transactions of the Royal Society B: Biological Sciences 366, no. 1564 (February 27, 2011): 540–53. http://dx.doi.org/10.1098/rstb.2010.0184.
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Constructing an internal representation of the world from successive visual fixations, i.e. separated by saccadic eye movements, is known as trans-saccadic perception. Research on trans-saccadic perception (TSP) has been traditionally aimed at resolving the problems of memory capacity and visual integration across saccades. In this paper, we review this literature on TSP with a focus on research showing that egocentric measures of the saccadic eye movement can be used to integrate simple object features across saccades, and that the memory capacity for items retained across saccades, like visual working memory, is restricted to about three to four items. We also review recent transcranial magnetic stimulation experiments which suggest that the right parietal eye field and frontal eye fields play a key functional role in spatial updating of objects in TSP. We conclude by speculating on possible cortical mechanisms for governing egocentric spatial updating of multiple objects in TSP.
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Binda, Paola, and Maria Concetta Morrone. "Vision During Saccadic Eye Movements." Annual Review of Vision Science 4, no. 1 (September 15, 2018): 193–213. http://dx.doi.org/10.1146/annurev-vision-091517-034317.
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The perceptual consequences of eye movements are manifold: Each large saccade is accompanied by a drop of sensitivity to luminance-contrast, low-frequency stimuli, impacting both conscious vision and involuntary responses, including pupillary constrictions. They also produce transient distortions of space, time, and number, which cannot be attributed to the mere motion on the retinae. All these are signs that the visual system evokes active processes to predict and counteract the consequences of saccades. We propose that a key mechanism is the reorganization of spatiotemporal visual fields, which transiently increases the temporal and spatial uncertainty of visual representations just before and during saccades. On one hand, this accounts for the spatiotemporal distortions of visual perception; on the other hand, it implements a mechanism for fusing pre- and postsaccadic stimuli. This, together with the active suppression of motion signals, ensures the stability and continuity of our visual experience.
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Awater, Holger, and Markus Lappe. "Perception of Visual Space at the Time of Pro- and Anti-Saccades." Journal of Neurophysiology 91, no. 6 (June 2004): 2457–64. http://dx.doi.org/10.1152/jn.00821.2003.
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The localization of peri-saccadically flashed objects shows two types of errors: first, a uniform shift in saccade direction, and second, a compression of visual space around the saccade target. Whereas the uniform shift occurs when the experiment is performed in complete darkness compression occurs when additional visual references are available. Thus peri-saccadic mislocalization contains motor and visual components. To distinguish between both factors we compared peri-saccadic localization errors during pro- and anti-saccades. In the case of anti-saccades, the visual cue that elicits the saccade and the actual eye movement are in opposite directions. We asked whether peri-saccadic compression can be observed with anti-saccades, and if so, whether the compression is directed toward the visual cue or follows the actual eye movement. In blocked trials, subjects performed saccades either toward a visual cue (pro-saccade) or to the mirrored position opposite to a visual cue (anti-saccade). Peri-saccadically, we flashed a thin vertical bar at one of four possible locations. Subjects had to indicate the perceived position of the bar with a mouse pointer about 500 ms after the saccade. Experiments were performed in complete darkness and with visual references. Peri-saccadic mislocalizations occurred during anti-saccades. The mislocalizations were very similar for pro- and anti-saccades in magnitude and direction. For both, pro- and anti-saccades, mislocalizations were directed toward the actual eye movement and not the visual cue.
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Goettker, Alexander, Doris I. Braun, Alexander C. Schütz, and Karl R. Gegenfurtner. "Execution of saccadic eye movements affects speed perception." Proceedings of the National Academy of Sciences 115, no. 9 (February 13, 2018): 2240–45. http://dx.doi.org/10.1073/pnas.1704799115.
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Due to the foveal organization of our visual system we have to constantly move our eyes to gain precise information about our environment. Doing so massively alters the retinal input. This is problematic for the perception of moving objects, because physical motion and retinal motion become decoupled and the brain has to discount the eye movements to recover the speed of moving objects. Two different types of eye movements, pursuit and saccades, are combined for tracking. We investigated how the way we track moving targets can affect the perceived target speed. We found that the execution of corrective saccades during pursuit initiation modifies how fast the target is perceived compared with pure pursuit. When participants executed a forward (catch-up) saccade they perceived the target to be moving faster. When they executed a backward saccade they perceived the target to be moving more slowly. Variations in pursuit velocity without corrective saccades did not affect perceptual judgments. We present a model for these effects, assuming that the eye velocity signal for small corrective saccades gets integrated with the retinal velocity signal during pursuit. In our model, the execution of corrective saccades modulates the integration of these two signals by giving less weight to the retinal information around the time of corrective saccades.
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Chen, Jing, Matteo Valsecchi, and Karl R. Gegenfurtner. "Saccadic suppression measured by steady-state visual evoked potentials." Journal of Neurophysiology 122, no. 1 (July 1, 2019): 251–58. http://dx.doi.org/10.1152/jn.00712.2018.
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Visual sensitivity is severely impaired during the execution of saccadic eye movements. This phenomenon has been extensively characterized in human psychophysics and nonhuman primate single-neuron studies, but a physiological characterization in humans is less established. Here, we used a method based on steady-state visually evoked potential (SSVEP), an oscillatory brain response to periodic visual stimulation, to examine how saccades affect visual sensitivity. Observers made horizontal saccades back and forth, while horizontal black-and-white gratings flickered at 5–30 Hz in the background. We analyzed EEG epochs with a length of 0.3 s either centered at saccade onset (saccade epochs) or centered at fixations half a second before the saccade (fixation epochs). Compared with fixation epochs, saccade epochs showed a broadband power increase, which most likely resulted from saccade-related EEG activity. The execution of saccades, however, led to an average reduction of 57% in the SSVEP amplitude at the stimulation frequency. This result provides additional evidence for an active saccadic suppression in the early visual cortex in humans. Compared with previous functional MRI and EEG studies, an advantage of this approach lies in its capability to trace the temporal dynamics of neural activity throughout the time course of a saccade. In contrast to previous electrophysiological studies in nonhuman primates, we did not find any evidence for postsaccadic enhancement, even though simulation results show that our method would have been able to detect it. We conclude that SSVEP is a useful technique to investigate the neural correlates of visual perception during saccadic eye movements in humans. NEW & NOTEWORTHY We make fast ballistic saccadic eye movements a few times every second. At the time of saccades, visual sensitivity is severely impaired. The present study uses steady-state visually evoked potentials to reveal a neural correlate of the fine temporal dynamics of these modulations at the time of saccades in humans. We observed a strong reduction (57%) of visually driven neural activity associated with saccades but did not find any evidence for postsaccadic enhancement.
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Ignashchenkova, A., S. Dash, P. W. Dicke, T. Haarmeier, M. Glickstein, and P. Thier. "Normal Spatial Attention But Impaired Saccades and Visual Motion Perception After Lesions of the Monkey Cerebellum." Journal of Neurophysiology 102, no. 6 (December 2009): 3156–68. http://dx.doi.org/10.1152/jn.00659.2009.
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Lesions of the cerebellum produce deficits in movement and motor learning. Saccadic dysmetria, for example, is caused by lesions of the posterior cerebellar vermis. Monkeys and patients with such lesions are unable to modify the amplitude of saccades. Some have suggested that the effects on eye movements might reflect a more global cognitive deficit caused by the cerebellar lesion. We tested that idea by studying the effects of vermis lesions on attention as well as saccadic eye movements, visual motion perception, and luminance change detection. Lesions in posterior vermis of four monkeys caused the known deficits in saccadic control. Attention tested by examination of acuity threshold changes induced by prior cueing of the location of the targets remained normal after vermis lesions. Luminance change detection was also unaffected by the lesions. In one case, after a lesion restricted to lobulus VIII, the animal had impaired visual motion perception.
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Hershberger, Wayne. "Saccadic eye movements and the perception of visual direction." Perception & Psychophysics 41, no. 1 (January 1987): 35–44. http://dx.doi.org/10.3758/bf03208211.
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Lee, Jungah, and Choongkil Lee. "Changes in visual motion perception before saccadic eye movements." Vision Research 45, no. 11 (May 2005): 1447–57. http://dx.doi.org/10.1016/j.visres.2004.12.008.
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Castaldi, Elisa, David Burr, Marco Turi, and Paola Binda. "Fast saccadic eye-movements in humans suggest that numerosity perception is automatic and direct." Proceedings of the Royal Society B: Biological Sciences 287, no. 1935 (September 23, 2020): 20201884. http://dx.doi.org/10.1098/rspb.2020.1884.
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Fast saccades are rapid automatic oculomotor responses to salient and ecologically important visual stimuli such as animals and faces. Discriminating the number of friends, foe, or prey may also have an evolutionary advantage. In this study, participants were asked to saccade rapidly towards the more numerous of two arrays. Participants could discriminate numerosities with high accuracy and great speed, as fast as 190 ms. Intermediate numerosities were more likely to elicit fast saccades than very low or very high numerosities. Reaction-times for vocal responses (collected in a separate experiment) were slower, did not depend on numerical range, and correlated only with the slow not the fast saccades, pointing to different systems. The short saccadic reaction-times we observe are surprising given that discrimination using numerosity estimation is thought to require a relatively complex neural circuit, with several relays of information through the parietal and prefrontal cortex. Our results suggest that fast numerosity-driven saccades may be generated on a single feed-forward pass of information recruiting a primitive system that cuts through the cortical hierarchy and rapidly transforms the numerosity information into a saccade command.
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Vliegen, Joyce, Tom J. Van Grootel, and A. John Van Opstal. "Gaze Orienting in Dynamic Visual Double Steps." Journal of Neurophysiology 94, no. 6 (December 2005): 4300–4313. http://dx.doi.org/10.1152/jn.00027.2005.
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Visual stimuli are initially represented in a retinotopic reference frame. To maintain spatial accuracy of gaze (i.e., eye in space) despite intervening eye and head movements, the visual input could be combined with dynamic feedback about ongoing gaze shifts. Alternatively, target coordinates could be updated in advance by using the preprogrammed gaze-motor command (“predictive remapping”). So far, previous experiments have not dissociated these possibilities. Here we study whether the visuomotor system accounts for saccadic eye–head movements that occur during target presentation. In this case, the system has to deal with fast dynamic changes of the retinal input and with highly variable changes in relative eye and head movements that cannot be preprogrammed by the gaze control system. We performed visual–visual double-step experiments in which a brief (50-ms) stimulus was presented during a saccadic eye–head gaze shift toward a previously flashed visual target. Our results show that gaze shifts remain accurate under these dynamic conditions, even for stimuli presented near saccade onset, and that eyes and head are driven in oculocentric and craniocentric coordinates, respectively. These results cannot be explained by a predictive remapping scheme. We propose that the visuomotor system adequately processes dynamic changes in visual input that result from self-initiated gaze shifts, to construct a stable representation of visual targets in an absolute, supraretinal (e.g., world) reference frame. Predictive remapping may subserve transsaccadic integration, thus enabling perception of a stable visual scene despite eye movements, whereas dynamic feedback ensures accurate actions (e.g., eye–head orienting) to a selected goal.
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Crowder, Nathan A., Nicholas S. C. Price, Michael J. Mustari, and Michael R. Ibbotson. "Direction and Contrast Tuning of Macaque MSTd Neurons During Saccades." Journal of Neurophysiology 101, no. 6 (June 2009): 3100–3107. http://dx.doi.org/10.1152/jn.91254.2008.
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Saccades are rapid eye movements that change the direction of gaze, although the full-field image motion associated with these movements is rarely perceived. The attenuation of visual perception during saccades is referred to as saccadic suppression. The mechanisms that produce saccadic suppression are not well understood. We recorded from neurons in the dorsal medial superior temporal area (MSTd) of alert macaque monkeys and compared the neural responses produced by the retinal slip associated with saccades (active motion) to responses evoked by identical motion presented during fixation (passive motion). We provide evidence for a neural correlate of saccadic suppression and expand on two contentious results from previous studies. First, we confirm the finding that some neurons in MSTd reverse their preferred direction during saccades. We quantify this effect by calculating changes in direction tuning index for a large cell population. Second, it has been noted that neural activity associated with saccades can arrive in the parietal cortex ≤30 ms earlier than activity produced by similar visual stimulation during fixation. This led to the question of whether the saccade-related responses were visual in origin or were motor signals arising from saccade-planning areas of the brain. By comparing the responses to saccades made over textured backgrounds of different contrasts, we provide strong evidence that saccade-related responses were visual in origin. Refinements of the possible models of saccadic suppression are discussed.
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Deubel, H., S. Shimojo, and I. Paprotta. "The Preparation of Goal-Directed Movements Requires Selective Visual Attention: Evidence from the Line-Motion Illusion." Perception 26, no. 1_suppl (August 1997): 124. http://dx.doi.org/10.1068/v970060.
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Previous research has demonstrated that visual attention is focused on the movement target, both before saccadic eye movements and before manual reaching, allowing for spatially selective object recognition (Deubel and Schneider, 1996 Vision Research36 1827 – 1837; Deubel, Schneider, and Paprotta, 1996 Perception Supplement, 13 – 19). Here we study the illusory line motion effect (Hikosaka et al, 1993 Vision Research33 1219 – 1240) in a dual-task paradigm to further investigate the coupling of attention and movement target selection. Subjects were presented a display with two potential movement targets (small circles). When one of the circles flashed, they performed a reaching movement with the unseen hand to the other stimulus; movements were registered with a Polhemus FastTrack system. At a SOA that was varied between 0 and 1000 ms after the movement cue, a line appeared and connected both stimuli. After the reaching movement, subjects indicated the perceived direction of line motion. In a second experiment, saccadic eye movements instead of reaching movements were studied. The data show that for short SOAs the subjects reported illusory line motion away from the cue location indicating that attention is automatically drawn to the cue. For longer SOAs but well before movement onset the illusory motion effect inverted—evidence for an attention shift to the movement target. The findings were very similar for manual reaching and for saccadic eye movements. The results confirm the hypothesis that the preparation of a goal-directed movement requires the attentional selection of the movement target. We discuss the assumption of a unitary attention mechanism which selects an object for visual processing, and simultaneously provides the information necessary for goal-directed motor action such as saccades, pointing, and grasping.
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Wolf, Christian, and Markus Lappe. "Vision as oculomotor reward: cognitive contributions to the dynamic control of saccadic eye movements." Cognitive Neurodynamics 15, no. 4 (January 25, 2021): 547–68. http://dx.doi.org/10.1007/s11571-020-09661-y.
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AbstractHumans and other primates are equipped with a foveated visual system. As a consequence, we reorient our fovea to objects and targets in the visual field that are conspicuous or that we consider relevant or worth looking at. These reorientations are achieved by means of saccadic eye movements. Where we saccade to depends on various low-level factors such as a targets’ luminance but also crucially on high-level factors like the expected reward or a targets’ relevance for perception and subsequent behavior. Here, we review recent findings how the control of saccadic eye movements is influenced by higher-level cognitive processes. We first describe the pathways by which cognitive contributions can influence the neural oculomotor circuit. Second, we summarize what saccade parameters reveal about cognitive mechanisms, particularly saccade latencies, saccade kinematics and changes in saccade gain. Finally, we review findings on what renders a saccade target valuable, as reflected in oculomotor behavior. We emphasize that foveal vision of the target after the saccade can constitute an internal reward for the visual system and that this is reflected in oculomotor dynamics that serve to quickly and accurately provide detailed foveal vision of relevant targets in the visual field.
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Lebedev, Mikhail A., Diana K. Douglass, Sohie Lee Moody, and Steven P. Wise. "Prefrontal Cortex Neurons Reflecting Reports of a Visual Illusion." Journal of Neurophysiology 85, no. 4 (April 1, 2001): 1395–411. http://dx.doi.org/10.1152/jn.2001.85.4.1395.
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When a small, focally attended visual stimulus and a larger background frame shift location at the same time, the frame's new location can affect spatial perception. For horizontal displacements on the order of 1–2°, when the frame moves more than the attended stimulus, human subjects may perceive that the attended stimulus has shifted to the right or left when it has not done so. However, that misapprehension does not disable accurate eye movements to the same stimulus. We trained a rhesus monkey to report the direction that an attended stimulus had shifted by making an eye movement to one of the two report targets. Then, using conditions that induce displacement illusions in human subjects, we tested the hypothesis that neuronal activity in the prefrontal cortex (PF) would reflect the displacement directions reported by the monkey, even when they conflicted with the actual displacement, if any, of the attended stimulus. We also predicted that these cells would have directional selectivity for movements used to make those reports, but not for similar eye movements made to fixate the attended stimulus. A population of PF neurons showed the predicted properties, which could not be accounted for on the basis of either eye-movement or frame-shift parameters. This activity, termed report-related, began approximately 150 ms before the onset of the reporting saccade. Another population of PF neurons showed greater directional selectivity for saccadic eye movements made to fixate the attended stimulus than for similar saccades made to report its displacement. In view of the evidence that PF functions to integrate inputs and actions occurring at different times and places, the present findings support the idea that such integration involves movements to acquire response targets, directly, as well as actions guided by less direct response rules, such as perceptual reports.
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Mathôt, Sebastiaan, and Jan Theeuwes. "Visual attention and stability." Philosophical Transactions of the Royal Society B: Biological Sciences 366, no. 1564 (February 27, 2011): 516–27. http://dx.doi.org/10.1098/rstb.2010.0187.
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In the present review, we address the relationship between attention and visual stability. Even though with each eye, head and body movement the retinal image changes dramatically, we perceive the world as stable and are able to perform visually guided actions. However, visual stability is not as complete as introspection would lead us to believe. We attend to only a few items at a time and stability is maintained only for those items. There appear to be two distinct mechanisms underlying visual stability. The first is a passive mechanism: the visual system assumes the world to be stable, unless there is a clear discrepancy between the pre- and post-saccadic image of the region surrounding the saccade target. This is related to the pre-saccadic shift of attention, which allows for an accurate preview of the saccade target. The second is an active mechanism: information about attended objects is remapped within retinotopic maps to compensate for eye movements. The locus of attention itself, which is also characterized by localized retinotopic activity, is remapped as well. We conclude that visual attention is crucial in our perception of a stable world.
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Rao, Hrishikesh M., J. Patrick Mayo, and Marc A. Sommer. "Circuits for presaccadic visual remapping." Journal of Neurophysiology 116, no. 6 (December 1, 2016): 2624–36. http://dx.doi.org/10.1152/jn.00182.2016.
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Saccadic eye movements rapidly displace the image of the world that is projected onto the retinas. In anticipation of each saccade, many neurons in the visual system shift their receptive fields. This presaccadic change in visual sensitivity, known as remapping, was first documented in the parietal cortex and has been studied in many other brain regions. Remapping requires information about upcoming saccades via corollary discharge. Analyses of neurons in a corollary discharge pathway that targets the frontal eye field (FEF) suggest that remapping may be assembled in the FEF's local microcircuitry. Complementary data from reversible inactivation, neural recording, and modeling studies provide evidence that remapping contributes to transsaccadic continuity of action and perception. Multiple forms of remapping have been reported in the FEF and other brain areas, however, and questions remain about the reasons for these differences. In this review of recent progress, we identify three hypotheses that may help to guide further investigations into the structure and function of circuits for remapping.
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Ruiz-Ruiz, Mario, and Julio C. Martinez-Trujillo. "Human Updating of Visual Motion Direction During Head Rotations." Journal of Neurophysiology 99, no. 5 (May 2008): 2558–76. http://dx.doi.org/10.1152/jn.00931.2007.
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Previous studies have demonstrated that human subjects update the location of visual targets for saccades after head and body movements and in the absence of visual feedback. This phenomenon is known as spatial updating. Here we investigated whether a similar mechanism exists for the perception of motion direction. We recorded eye positions in three dimensions and behavioral responses in seven subjects during a motion task in two different conditions: when the subject's head remained stationary and when subjects rotated their heads around an anteroposterior axis (head tilt). We demonstrated that after head-tilt subjects updated the direction of saccades made in the perceived stimulus direction (direction of motion updating), the amount of updating varied across subjects and stimulus directions, the amount of motion direction updating was highly correlated with the amount of spatial updating during a memory-guided saccade task, subjects updated the stimulus direction during a two-alternative forced-choice direction discrimination task in the absence of saccadic eye movements (perceptual updating), perceptual updating was more accurate than motion direction updating involving saccades, and subjects updated motion direction similarly during active and passive head rotation. These results demonstrate the existence of an updating mechanism for the perception of motion direction in the human brain that operates during active and passive head rotations and that resembles the one of spatial updating. Such a mechanism operates during different tasks involving different motor and perceptual skills (saccade and motion direction discrimination) with different degrees of accuracy.
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Tatler, Benjamin W., and Nicholas J. Wade. "On Nystagmus, Saccades, and Fixations." Perception 32, no. 2 (February 2003): 167–84. http://dx.doi.org/10.1068/p3395.
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Investigations of the ways in which the eyes move came to prominence in the 19th century, but techniques for measuring them more precisely emerged in the 20th century. When scanning a scene or text the eyes engage in periods of relative stability (fixations) interspersed with ballistic rotations (saccades). The saccade-and-fixate strategy, associated with voluntary eye movements, was first uncovered in the context of involuntary eye movements following body rotation. This pattern of eye movements is now referred to as nystagmus, and involves periods of slow eye movements, during which objects are visible, and rapid returns, when they are not; it is based on a vestibular reflex which attempts to achieve image stabilisation. Post-rotational nystagmus was reported in the late 18th century (by Wells), with afterimages used as a means of retinal stabilisation to distinguish between movement of the eyes and of the environment. Nystagmus was linked to vestibular stimulation in the 19th century, and Mach, Breuer, and Crum Brown all described its fast and slow phases. Wells and Breuer proposed that there was no visual awareness during the ballistic phase (saccadic suppression). The saccade-and-fixate strategy highlighted by studies of nystagmus was shown to apply to tasks like reading by Dodge, who used more sophisticated photographic techniques to examine oculomotor kinematics. The relationship between eye movements and perception, following earlier intuitions by Wells and Breuer, was explored by Dodge, and has been of fundamental importance in the direction of vision research over the last century.
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Fabius, Jasper H., Alessio Fracasso, Tanja C. W. Nijboer, and Stefan Van der Stigchel. "Time course of spatiotopic updating across saccades." Proceedings of the National Academy of Sciences 116, no. 6 (January 17, 2019): 2027–32. http://dx.doi.org/10.1073/pnas.1812210116.
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Humans move their eyes several times per second, yet we perceive the outside world as continuous despite the sudden disruptions created by each eye movement. To date, the mechanism that the brain employs to achieve visual continuity across eye movements remains unclear. While it has been proposed that the oculomotor system quickly updates and informs the visual system about the upcoming eye movement, behavioral studies investigating the time course of this updating suggest the involvement of a slow mechanism, estimated to take more than 500 ms to operate effectively. This is a surprisingly slow estimate, because both the visual system and the oculomotor system process information faster. If spatiotopic updating is indeed this slow, it cannot contribute to perceptual continuity, because it is outside the temporal regime of typical oculomotor behavior. Here, we argue that the behavioral paradigms that have been used previously are suboptimal to measure the speed of spatiotopic updating. In this study, we used a fast gaze-contingent paradigm, using high phi as a continuous stimulus across eye movements. We observed fast spatiotopic updating within 150 ms after stimulus onset. The results suggest the involvement of a fast updating mechanism that predictively influences visual perception after an eye movement. The temporal characteristics of this mechanism are compatible with the rate at which saccadic eye movements are typically observed in natural viewing.
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Burr, David C., M. Concetta Morrone, and John Ross. "Separate visual representations for perception and action revealed by saccadic eye movements." Current Biology 11, no. 10 (May 2001): 798–802. http://dx.doi.org/10.1016/s0960-9822(01)00183-x.
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Filin, V. A. "Saccade Automation." Perception 26, no. 1_suppl (August 1997): 141. http://dx.doi.org/10.1068/v970123.
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The comparative analysis of basic saccade characteristics (interval, amplitude, and coefficient of asymmetry) has shown considerable similarities in adults and first-year babies. Distribution curves of intersaccadic intervals under different test conditions all have only one maximum in the range of about 0.4 s, and in all cases the most frequently met intersaccadic intervals (0.1 – 1.0) comprised comparable proportions of all (71.5% – 90.5%). The concept of saccade automation was formulated on the basis of these data (Filin and Filina, 1989 Zhurnal Vysshei Nervnoi Deyatelnosti29 603 – 607). In our opinion saccade automation is the basic law of saccadic activity, and all diversity of eye-movement activity takes place against the background of saccade automation. Microsaccades and macrosaccades, nystagmus, and rapid eye movements during sleep may be seen as special cases of saccade automation. Saccade automation is conditioned by the activity of brain structures with pacemaker function. Thus saccades are driven at one basic frequency, which is modulated by afferent influences from the retina of vestibular apparatus, proprioreceptors of eye and neck muscles, and efferent signals (forehead and occipital sections of cerebral cortex, cerebellum). At the same time, only one parameter is modulated at one particular moment, for example saccade amplitude in which case interval and orientation are given in a ready form. Saccade automation has a great functional importance. It increases the scanned area tenfold, it provides compensation of defects in the sensors and the impellent eye apparatus and for the deletion of consecutive images, maintaining the continuity of visual perception. Moving the image on the retina increases the information of the visual channel.
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Makin, Alexis D. J., Ellen Poliakoff, Giulia Rampone, and Marco Bertamini. "Spontaneous Ocular Scanning of Visual Symmetry Is Similar During Classification and Evaluation Tasks." i-Perception 11, no. 5 (September 2020): 204166952094635. http://dx.doi.org/10.1177/2041669520946356.
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Visual symmetry perception and symmetry preference have been studied extensively. However, less is known about how people spontaneously scan symmetrical stimuli with their eyes. We thus examined spontaneous saccadic eye movements when participants ( N = 20) observed patterns with horizontal or vertical mirror reflection. We found that participants tend to make saccades along the axis of reflection and that this oculomotor behaviour was similar during objective classification and subjective evaluation tasks. The axis-scanning behaviour generates a dynamic sequence of novel symmetrical images from a single static stimulus. This could aid symmetry perception and evaluation by enhancing the neural response to symmetry.
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Sinelnikov, S. N., I. O. Naturalnikov, A. A. Blaginin, and O. S. Agadzhanyan. "Differences in the perception of digital information of aviation operators depending on the degree of extraversion." Bulletin of the Russian Military Medical Academy 22, no. 4 (December 15, 2020): 76–81. http://dx.doi.org/10.17816/brmma62809.
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Considers the influence of the degree of extraversion on the perception of digital information by aviation operators. The analysis of the results of solving the Schulte tables by the test subjects on the NS-Psychotest hardware complex based on the recording of the eye track, performed using a stationary eye tracking device RED250mobile eye tracking device was carried out. While performing the search function, the number of saccadic movements, their amplitude, and the search time for a given digital value were registered. It has been revealed, that introverts during realization eyes search function perform less saccadic movements and spend less time on it than extraverts do. Significant differences have been found during resolving search tasks depending on degree of extraversion. Some interconnections of extension the latent period of the saccade with complication of solving process the cognitive problem were also found. It was found out, that increase in speed of saccadic movements of eyes leads to low efficiency of results of search task execution. Results of conducted research emphasize value of individual approach to medical flight service taking into account psychological features of flight crew in conditions of rapid progress in aviation technologies and means of visualisation of flight information. The obtained data reveal some features of information perception by operators of complex ergatic systems, the study of which in the future will help to maintain the reserves of attention in a continuous stream of incoming data, and thereby reduce the load on the visual analyzer and increase the reliability of professional activities of flight crew.
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Awater, Holger, David Burr, Markus Lappe, M. Concetta Morrone, and Michael E. Goldberg. "Effect of Saccadic Adaptation on Localization of Visual Targets." Journal of Neurophysiology 93, no. 6 (June 2005): 3605–14. http://dx.doi.org/10.1152/jn.01013.2003.
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Objects flashed briefly around the time of a saccadic eye movement are grossly mislocalized by human subjects, so they appear to be compressed toward the endpoint of the saccade. In this study, we investigate spatial localization during saccadic adaptation to examine whether the focus of compression tends toward the intended saccadic target or at the endpoint of the actual (adapted) movement. We report two major results. First, that peri-saccadic focus of the compression did not occur at the site of the initial saccadic target, but tended toward the actual landing site of the saccade. Second, and more surprisingly, we observed a large long-term perceptual distortion of space, lasting for hundreds of milliseconds. This distortion did not occur over the whole visual field but was limited to a local region of visual space around the saccade target, suggesting that saccadic adaptation induces a visuo-topic remapping of space. The results imply that the mechanisms controlling saccadic adaptation also affect perception of space and point to a strong perceptual plasticity coordinated with the well-documented plasticity of the motor system.
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Duchesne, Jean, Vincent Bouvier, Julien Guillemé, and Olivier A. Coubard. "Maxwellian Eye Fixation during Natural Scene Perception." Scientific World Journal 2012 (2012): 1–12. http://dx.doi.org/10.1100/2012/956340.
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When we explore a visual scene, our eyes make saccades to jump rapidly from one area to another and fixate regions of interest to extract useful information. While the role of fixation eye movements in vision has been widely studied, their random nature has been a hitherto neglected issue. Here we conducted two experiments to examine the Maxwellian nature of eye movements during fixation. In Experiment 1, eight participants were asked to perform free viewing of natural scenes displayed on a computer screen while their eye movements were recorded. For each participant, the probability density function (PDF) of eye movement amplitude during fixation obeyed the law established by Maxwell for describing molecule velocity in gas. Only the mean amplitude of eye movements varied with expertise, which was lower in experts than novice participants. In Experiment 2, two participants underwent fixed time, free viewing of natural scenes and of their scrambled version while their eye movements were recorded. Again, the PDF of eye movement amplitude during fixation obeyed Maxwell’s law for each participant and for each scene condition (normal or scrambled). The results suggest that eye fixation during natural scene perception describes a random motion regardless of top-down or of bottom-up processes.
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Henderson, John M. "Transsaccadic Memory and Integration During Real-World Object Perception." Psychological Science 8, no. 1 (January 1997): 51–55. http://dx.doi.org/10.1111/j.1467-9280.1997.tb00543.x.
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What is the nature of the information that is preserved and combined across saccadic eye movements during the visual analysis of real-world objects? The two experiments reported investigated transsaccadic memory and transsaccadic integration, respectively In the critical condition, participants were presented with one set of contours from an object during one fixation and with a complementary set of contours during the next fixation In Experiment 1, participants could at best inconsistently detect contour changes across the saccade In Experiment 2, a change in visible contour had no influence on object identification These results suggest that a veridical representation of object contour is neither consistently preserved nor integrated across a saccade
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Tegetmeyer, Helmut, and Anja Wenger. "Influence of visual perception on spatial coding of saccadic eye movements and fixation." Neuro-Ophthalmology 28, no. 5-6 (January 2004): 197–204. http://dx.doi.org/10.1080/01658100490887931.
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Gee, Angela L., Anna E. Ipata, and Michael E. Goldberg. "Activity in V4 Reflects the Direction, But Not the Latency, of Saccades During Visual Search." Journal of Neurophysiology 104, no. 4 (October 2010): 2187–93. http://dx.doi.org/10.1152/jn.00898.2009.
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We constantly make eye movements to bring objects of interest onto the fovea for more detailed processing. Activity in area V4, a prestriate visual area, is enhanced at the location corresponding to the target of an eye movement. However, the precise role of activity in V4 in relation to these saccades and the modulation of other cortical areas in the oculomotor system remains unknown. V4 could be a source of visual feature information used to select the eye movement, or alternatively, it could reflect the locus of spatial attention. To test these hypotheses, we trained monkeys on a visual search task in which they were free to move their eyes. We found that activity in area V4 reflected the direction of the upcoming saccade but did not predict the latency of the saccade in contrast to activity in the lateral intraparietal area (LIP). We suggest that the signals in V4, unlike those in LIP, are not directly involved in the generation of the saccade itself but rather are more closely linked to visual perception and attention. Although V4 and LIP have different roles in spatial attention and preparing eye movements, they likely perform complimentary processes during visual search.
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Fischer, B., and H. Weber. "Express saccades and visual attention." Behavioral and Brain Sciences 16, no. 3 (September 1993): 553–67. http://dx.doi.org/10.1017/s0140525x00031575.
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AbstractOne of the most intriguing and controversial observations in oculomotor research in recent years is the phenomenon of express saccades in monkeys and man. These are saccades with such short reaction times (100 msec in man, 70 msec in monkeys) that some experts on eye movements still regard them as artifacts or as anticipatory reactions that do not need any further explanation. On the other hand, some research groups consider them not only authentic but also a valuable means of investigating the mechanisms of saccade generation, the coordination of vision and eye movements, and the mechanisms of visual attention.This target article puts together pieces of experimental evidence in oculomotor and related research – with special emphasis on the express saccade – to enhance our present understanding of the coordination of vision, visual attention, and the eye movements subserving visual perception and cognition.We hypothesize that an optomotor reflex is responsible for the occurrence of express saccades, one that is controlled by higher brain functions involved in disengaged visual attention and decision making. We propose a neural network as the basis for more elaborate mathematical models or computer simulations of the optomotor system in primates.
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Buonocore, Antimo, Chih-Yang Chen, Xiaoguang Tian, Saad Idrees, Thomas A. Münch, and Ziad M. Hafed. "Alteration of the microsaccadic velocity-amplitude main sequence relationship after visual transients: implications for models of saccade control." Journal of Neurophysiology 117, no. 5 (May 1, 2017): 1894–910. http://dx.doi.org/10.1152/jn.00811.2016.
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Microsaccades occur during gaze fixation to correct for miniscule foveal motor errors. The mechanisms governing such fine oculomotor control are still not fully understood. In this study, we explored microsaccade control by analyzing the impacts of transient visual stimuli on these movements’ kinematics. We found that such kinematics can be altered in systematic ways depending on the timing and spatial geometry of visual transients relative to the movement goals. In two male rhesus macaques, we presented peripheral or foveal visual transients during an otherwise stable period of fixation. Such transients resulted in well-known reductions in microsaccade frequency, and our goal was to investigate whether microsaccade kinematics would additionally be altered. We found that both microsaccade timing and amplitude were modulated by the visual transients, and in predictable manners by these transients’ timing and geometry. Interestingly, modulations in the peak velocity of the same movements were not proportional to the observed amplitude modulations, suggesting a violation of the well-known “main sequence” relationship between microsaccade amplitude and peak velocity. We hypothesize that visual stimulation during movement preparation affects not only the saccadic “Go” system driving eye movements but also a “Pause” system inhibiting them. If the Pause system happens to be already turned off despite the new visual input, movement kinematics can be altered by the readout of additional visually evoked spikes in the Go system coding for the flash location. Our results demonstrate precise control over individual microscopic saccades and provide testable hypotheses for mechanisms of saccade control in general. NEW & NOTEWORTHY Microsaccadic eye movements play an important role in several aspects of visual perception and cognition. However, the mechanisms for microsaccade control are still not fully understood. We found that microsaccade kinematics can be altered in a systematic manner by visual transients, revealing a previously unappreciated and exquisite level of control by the oculomotor system of even the smallest saccades. Our results suggest precise temporal interaction between visual, motor, and inhibitory signals in microsaccade control.
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Nicolas, Judith, Aline Bompas, Romain Bouet, Olivier Sillan, Eric Koun, Christian Urquizar, Aurélie Bidet-Caulet, and Denis Pélisson. "Saccadic Adaptation Boosts Ongoing Gamma Activity in a Subsequent Visuoattentional Task." Cerebral Cortex 29, no. 9 (October 6, 2018): 3606–17. http://dx.doi.org/10.1093/cercor/bhy241.
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Abstract Attention and saccadic adaptation (SA) are critical components of visual perception, the former enhancing sensory processing of selected objects, the latter maintaining the eye movements accuracy toward them. Recent studies propelled the hypothesis of a tight functional coupling between these mechanisms, possibly due to shared neural substrates. Here, we used magnetoencephalography to investigate for the first time the neurophysiological bases of this coupling and of SA per se. We compared visual discrimination performance of 12 healthy subjects before and after SA. Eye movements and magnetic signals were recorded continuously. Analyses focused on gamma band activity (GBA) during the pretarget period of the discrimination and the saccadic tasks. We found that GBA increases after SA. This increase was found in the right hemisphere for both postadaptation saccadic and discrimination tasks. For the latter, GBA also increased in the left hemisphere. We conclude that oculomotor plasticity involves GBA modulation within an extended neural network which persists after SA, suggesting a possible role of gamma oscillations in the coupling between SA and attention.
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Mizuno, Fumio, Tomoaki Hayasaka, and Takami Yamaguchi. "Providing a human user artificial ability to control their eyes independently with various eye movement patterns." Seeing and Perceiving 25 (2012): 171–72. http://dx.doi.org/10.1163/187847612x648017.
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Humans have the capability to flexibly adapt to visual stimulation, such as spatial inversion in which a person wears glasses that display images upside down for long periods of time (Ewert, 1930; Snyder and Pronko, 1952; Stratton, 1887). To investigate feasibility of extension of vision and the flexible adaptation of the human visual system with binocular rivalry, we developed a system that provides a human user with the artificial oculomotor ability to control their eyes independently for arbitrary directions, and we named the system Virtual Chameleon having to do with Chameleons (Mizuno et al., 2010, 2011). The successful users of the system were able to actively control visual axes by manipulating 3D sensors held by their both hands, to watch independent fields of view presented to the left and right eyes, and to look around as chameleons do. Although it was thought that those independent fields of view provided to the user were formed by eye movements control corresponding to pursuit movements on human, the system did not have control systems to perform saccadic movements and compensatory movements as numerous animals including human do. Fluctuations in dominance and suppression with binocular rivalry are irregular, but it is possible to bias these fluctuations by boosting the strength of one rival image over the other (Blake and Logothetis, 2002). It was assumed that visual stimuli induced by various eye movements affect predominance. Therefore, in this research, we focused on influenced of patterns of eye movements on visual perception with binocular rivalry, and implemented functions to produce saccadic movements in Virtual Chameleon.
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Grujic, Nikola, Nils Brehm, Cordula Gloge, Weijie Zhuo, and Ziad M. Hafed. "Perisaccadic perceptual mislocalization is different for upward saccades." Journal of Neurophysiology 120, no. 6 (December 1, 2018): 3198–216. http://dx.doi.org/10.1152/jn.00350.2018.
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Saccadic eye movements, which dramatically alter retinal images, are associated with robust perimovement perceptual alterations. Such alterations, thought to reflect brain mechanisms for maintaining perceptual stability in the face of saccade-induced retinal image disruptions, are often studied by asking subjects to localize brief stimuli presented around the time of horizontal saccades. However, other saccade directions are not usually explored. Motivated by recently discovered asymmetries in upper and lower visual field representations in the superior colliculus, a structure important for both saccade generation and visual analysis, we observed significant differences in perisaccadic perceptual alterations for upward saccades relative to other saccade directions. We also found that, even for purely horizontal saccades, perceptual alterations differ for upper vs. lower retinotopic stimulus locations. Our results, coupled with conceptual modeling, suggest that perisaccadic perceptual alterations might critically depend on neural circuits, such as superior colliculus, that asymmetrically represent the upper and lower visual fields. NEW & NOTEWORTHY Brief visual stimuli are robustly mislocalized around the time of saccades. Such mislocalization is thought to arise because oculomotor and visual neural maps distort space through foveal magnification. However, other neural asymmetries, such as upper visual field magnification in the superior colliculus, may also exist, raising the possibility that interactions between saccades and visual stimuli would depend on saccade direction. We confirmed this behaviorally by exploring and characterizing perisaccadic perception for upward saccades.
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Wurtz, Robert H., Wilsaan M. Joiner, and Rebecca A. Berman. "Neuronal mechanisms for visual stability: progress and problems." Philosophical Transactions of the Royal Society B: Biological Sciences 366, no. 1564 (February 27, 2011): 492–503. http://dx.doi.org/10.1098/rstb.2010.0186.
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How our vision remains stable in spite of the interruptions produced by saccadic eye movements has been a repeatedly revisited perceptual puzzle. The major hypothesis is that a corollary discharge (CD) or efference copy signal provides information that the eye has moved, and this information is used to compensate for the motion. There has been progress in the search for neuronal correlates of such a CD in the monkey brain, the best animal model of the human visual system. In this article, we briefly summarize the evidence for a CD pathway to frontal cortex, and then consider four questions on the relation of neuronal mechanisms in the monkey brain to stable visual perception. First, how can we determine whether the neuronal activity is related to stable visual perception? Second, is the activity a possible neuronal correlate of the proposed transsaccadic memory hypothesis of visual stability? Third, are the neuronal mechanisms modified by visual attention and does our perceived visual stability actually result from neuronal mechanisms related primarily to the central visual field? Fourth, does the pathway from superior colliculus through the pulvinar nucleus to visual cortex contribute to visual stability through suppression of the visual blur produced by saccades?
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Moore, Tirin, and Mazyar Fallah. "Microstimulation of the Frontal Eye Field and Its Effects on Covert Spatial Attention." Journal of Neurophysiology 91, no. 1 (January 2004): 152–62. http://dx.doi.org/10.1152/jn.00741.2002.
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Many studies have established that the strength of visual perception and the strength of visual representations within visual cortex vary according to the focus of covert spatial attention. While it is clear that attention can modulate visual signals, the source of this modulation remains unknown. We have examined the possibility that saccade related mechanisms provide a source of spatial attention by studying the effects of electrical microstimulation of the frontal eye fields (FEF) on spatial attention. Monkeys performed a task in which they had to detect luminance changes of a peripheral target while ignoring a flashing distracter. The target luminance change could be preceded by stimulation of the FEF at current levels below that which evoked saccadic eye movements. We found that when the target change was preceded by stimulation of FEF, the monkey could detect smaller changes in target luminance. The increased sensitivity to the target change only occurred when the target was placed in the part of the visual field represented by neurons at the stimulation site. The magnitude of improvement depended on the temporal asynchrony of the stimulation onset and the target event. No significant effect of stimulation was observed when long intervals (>300 ms) between stimulation and the target event were used, and the magnitude of the increased sensitivity decreased systematically with increasing asynchrony. At the shortest asynchrony, FEF stimulation temporally overlapped the target event and the magnitude of the improvement was comparable to that of removing the distracter from the task. These results demonstrate that transient, but potent improvements in the deployment of covert spatial attention can be obtained by microstimulation of FEF sites from which saccadic eye movements are also evoked.
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Wang, Xin, and Pieter Jonker. "An Advanced Active Vision System with Multimodal Visual Odometry Perception for Humanoid Robots." International Journal of Humanoid Robotics 14, no. 03 (August 25, 2017): 1750006. http://dx.doi.org/10.1142/s0219843617500062.
Full textAbstract:
Using active vision to perceive surroundings instead of just passively receiving information, humans develop the ability to explore unknown environments. Humanoid robot active vision research has already half a century history. It covers comprehensive research areas and plenty of studies have been done. Nowadays, the new trend is to use a stereo setup or a Kinect with neck movements to realize active vision. However, human perception is a combination of eye and neck movements. This paper presents an advanced active vision system that works in a similar way as human vision. The main contributions are: a design of a set of controllers that mimic eye and neck movements, including saccade eye movements, pursuit eye movements, vestibulo-ocular reflex eye movements and vergence eye movements; an adaptive selection mechanism based on properties of objects to automatically choose an optimal tracking algorithm; a novel Multimodal Visual Odometry Perception method that combines stereopsis and convergence to enable robots to perform both precise action in action space and scene exploration in personal space. Experimental results prove the effectiveness and robustness of our system. Besides, the system works in real-time constraints with low-cost cameras and motors, providing an affordable solution for industrial applications.
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Krauzlis, Richard J., Laurent Goffart, and Ziad M. Hafed. "Neuronal control of fixation and fixational eye movements." Philosophical Transactions of the Royal Society B: Biological Sciences 372, no. 1718 (February 27, 2017): 20160205. http://dx.doi.org/10.1098/rstb.2016.0205.
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Ocular fixation is a dynamic process that is actively controlled by many of the same brain structures involved in the control of eye movements, including the superior colliculus, cerebellum and reticular formation. In this article, we review several aspects of this active control. First, the decision to move the eyes not only depends on target-related signals from the peripheral visual field, but also on signals from the currently fixated target at the fovea, and involves mechanisms that are shared between saccades and smooth pursuit. Second, eye position during fixation is actively controlled and depends on bilateral activity in the superior colliculi and medio-posterior cerebellum; disruption of activity in these circuits causes systematic deviations in eye position during both fixation and smooth pursuit eye movements. Third, the eyes are not completely still during fixation but make continuous miniature movements, including ocular drift and microsaccades, which are controlled by the same neuronal mechanisms that generate larger saccades. Finally, fixational eye movements have large effects on visual perception. Ocular drift transforms the visual input in ways that increase spatial acuity; microsaccades not only improve vision by relocating the fovea but also cause momentary changes in vision analogous to those caused by larger saccades. This article is part of the themed issue ‘Movement suppression: brain mechanisms for stopping and stillness’.
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Price, N. S. C., M. R. Ibbotson, S. Ono, and M. J. Mustari. "Rapid Processing of Retinal Slip During Saccades in Macaque Area MT." Journal of Neurophysiology 94, no. 1 (July 2005): 235–46. http://dx.doi.org/10.1152/jn.00041.2005.
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The primate middle temporal area (MT) is involved in the analysis and perception of visual motion, which is generated actively by eye and body movements and passively when objects move. We studied the responses of single cells in area MT of awake macaques, comparing the direction tuning and latencies of responses evoked by wide-field texture motion during fixation (passive viewing) and during rewarded, target-directed saccades and nonrewarded, spontaneous saccades over the same stationary texture (active viewing). We found that MT neurons have similar motion sensitivity and direction-selectivity for retinal slip associated with active and passive motion. No cells showed reversals in direction tuning between the active and passive viewing conditions. However, mean latencies were significantly different for saccade-evoked responses (30 ms) and stimulus-evoked responses (67 ms). Our results demonstrate that neurons in area MT retain their direction-selectivity and display reduced processing times during saccades. This rapid, accurate processing of peri-saccadic motion may facilitate postsaccadic ocular following reflexes or corrective saccades.
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Churan, Jan, Daniel Guitton, and Christopher C. Pack. "Spatiotemporal structure of visual receptive fields in macaque superior colliculus." Journal of Neurophysiology 108, no. 10 (November 15, 2012): 2653–67. http://dx.doi.org/10.1152/jn.00389.2012.
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Saccades are useful for directing the high-acuity fovea to visual targets that are of behavioral relevance. The selection of visual targets for eye movements involves the superior colliculus (SC), where many neurons respond to visual stimuli. Many of these neurons are also activated before and during saccades of specific directions and amplitudes. Although the role of the SC in controlling eye movements has been thoroughly examined, far less is known about the nature of the visual responses in this area. We have, therefore, recorded from neurons in the intermediate layers of the macaque SC, while using a sparse-noise mapping procedure to obtain a detailed characterization of the spatiotemporal structure of visual receptive fields. We find that SC responses to flashed visual stimuli start roughly 50 ms after the onset of the stimulus and last for on average ∼70 ms. About 50% of these neurons are strongly suppressed by visual stimuli flashed at certain locations flanking the excitatory center, and the spatiotemporal pattern of suppression exerts a predictable influence on the timing of saccades. This suppression may, therefore, contribute to the filtering of distractor stimuli during target selection. We also find that saccades affect the processing of visual stimuli by SC neurons in a manner that is quite similar to the saccadic suppression and postsaccadic enhancement that has been observed in the cortex and in perception. However, in contrast to what has been observed in the cortex, decreased visual sensitivity was generally associated with increased firing rates, while increased sensitivity was associated with decreased firing rates. Overall, these results suggest that the processing of visual stimuli by SC receptive fields can influence oculomotor behavior and that oculomotor signals originating in the SC can shape perisaccadic visual perception.
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Doyle, M. C., and R. J. Snowden. "Superior Detection of Audio-Visual Signals over Visual Signals: Are Overt Movements Necessary?" Perception 26, no. 1_suppl (August 1997): 129. http://dx.doi.org/10.1068/v970244.
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Perrott et al (1990 Perception & Psychophysics48 214 – 226) suggested that the use of auditory information to guide saccadic eye movements may mediate the facilitation of visual search by auditory spatial information. We modified a later paradigm (Perrott et al, 1991 Human Factors33 389 – 400) to re-examine the nature of auditory facilitation for both covert and overt orienting to targets located ±15° from a central fixation point. Participants made a 2AFC response to the orientation of a visual target in each of four conditions: the target was presented (1) alone, or target onset was accompanied by (2) a spatially coincident sound, (3) a centrally located ‘status’ sound, or (4) a change in the fixation point. The auditory stimulus was a 10 Hz click train: the visual target appeared on the left or right of the fixation point at ±15° azimuth and 0° elevation. In experiment 1 foveal vision was necessary to identify the target. However, the stimulus used in subsequent experiments could be accurately identified without overt receptor movement. Subjects were instructed to use eye movements (experiment 2) or to maintain fixation on a central cross throughout the session (experiment 3). Spatial and status sounds had a significant facilitatory effect on target identification both when overt and when covert orienting were employed. This strongly suggests that audio-visual facilitation is not dependent upon overt orienting.
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Thier, Peter, and Akshay Markanday. "Role of the Vermal Cerebellum in Visually Guided Eye Movements and Visual Motion Perception." Annual Review of Vision Science 5, no. 1 (September 15, 2019): 247–68. http://dx.doi.org/10.1146/annurev-vision-091718-015000.
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The cerebellar cortex is a crystal-like structure consisting of an almost endless repetition of a canonical microcircuit that applies the same computational principle to different inputs. The output of this transformation is broadcasted to extracerebellar structures by way of the deep cerebellar nuclei. Visually guided eye movements are accommodated by different parts of the cerebellum. This review primarily discusses the role of the oculomotor part of the vermal cerebellum [the oculomotor vermis (OMV)] in the control of visually guided saccades and smooth-pursuit eye movements. Both types of eye movements require the mapping of retinal information onto motor vectors, a transformation that is optimized by the OMV, considering information on past performance. Unlike the role of the OMV in the guidance of eye movements, the contribution of the adjoining vermal cortex to visual motion perception is nonmotor and involves a cerebellar influence on information processing in the cerebral cortex.
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Rolfs, Martin, and Sven Ohl. "Visual Suppression in the Superior Colliculus Around the Time of Microsaccades." Journal of Neurophysiology 105, no. 1 (January 2011): 1–3. http://dx.doi.org/10.1152/jn.00862.2010.
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Miniature eye movements jitter the retinal image unceasingly, raising the question of how perceptual continuity is achieved during visual fixation. Recent work discovered suppression of visual bursts in the superior colliculus around the time of microsaccades, tiny jerks of the eyes that support visual perception while gaze is fixed. This finding suggests that corollary discharge, supporting visual stability when rapid eye movements drastically shift the retinal image, may also exist for the smallest saccades.
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Latimer, Cyril, Catherine Stevens, Mark Irish, and Leanne Webber. "Attentional Biases in Geometric form Perception." Quarterly Journal of Experimental Psychology Section A 53, no. 3 (August 2000): 765–91. http://dx.doi.org/10.1080/713755915.
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This paper reports the operation of robust attentional bias to the top and right during perception of small, single geometric forms. Same/different judgements of successively presented standard and comparison forms are faster when local differences are located at top and right rather than in other regions of the forms. The bias persists when form size is reduced to approximately one degree of visual angle, and it is unaffected by saccadic eye movements and by instructions to attend to other reliably differentiating regions of the forms. Results lend support in various degrees to two of the possible explanations of the bias: (1) a static, skewed distribution of attentional resources around eye fixation; and (2) biased, covert scanning that commences invariably at the top and right of stim ulus forms. Origins of the bias in terms of possible left-hemispheric capacity for constructing representations of visual stimuli from parts, as well as in terms of reading experience and prevailing optic flow during locomotion through space are considered. Recent investigations of conditions under which the bias can be maintained or reduced are mentioned.
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Gilchrist, I. D., J. M. Findlay, and C. A. Heywood. "Converging Evidence for Two Separate Processes in Perceptual Grouping." Perception 25, no. 1_suppl (August 1996): 56. http://dx.doi.org/10.1068/v96l0310.
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Using a visual search paradigm, Gilchrist, Humphreys, Riddoch, and Neumann ( Journal of Experimental Psychology: Human Perception and Performance in press) demonstrated that grouping was mediated by a contrast-polarity-dependent surface-based process, and a contrast-independent edge-based process. A vertical pair of circles ‘popped out’ amongst horizontal pairs of circles as distractor only if the items within each pair had the same contrast polarity. Alternatively, if the circles were replaced with squares that had collinear edges, the vertical pair ‘popped out’ regardless of the contrast polarity of the squares. Here we report new data in which the role of these two grouping processes in the control of saccadic eye-movements was investigated. If subjects are presented with two items concurrently in an eye-movement task they will often make a saccade to the midpoint between the two items—this has been called the ‘global effect’. This effect is assumed to reflect some underlying integration of the visual information during the programming of saccade landing position. Distractor items that either shared the same polarity or had collinear edges with the target were found to affect the landing position of saccades. Distractors that had neither collinear edges nor common polarity produced a smaller global effect but the landing position was still affected. This suggests that the integration processes that underlie the global effect are sensitive to both common edge and surface properties. However, some integration may occur as a result of the mere presence of activity in the visual field.
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LEE, CHOONGKIL, and JUNGAH LEE. "Visual Motion Perception at the Time of Saccadic Eye Movements and its Relation to Spatial Mislocalization." Annals of the New York Academy of Sciences 1039, no. 1 (April 2005): 160–65. http://dx.doi.org/10.1196/annals.1325.015.
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LENCER, R., P. TRILLENBERG, K. TRILLENBERG-KRECKER, K. JUNGHANNS, A. KORDON, A. BROOCKS, F. HOHAGEN, W. HEIDE, and V. AROLT. "Smooth pursuit deficits in schizophrenia, affective disorder and obsessive–compulsive disorder." Psychological Medicine 34, no. 3 (April 2004): 451–60. http://dx.doi.org/10.1017/s0033291703001314.
Full textAbstract:
Background. In schizophrenia, affective disorders, and obsessive–compulsive disorder (OCD) dysfunction of frontal neuronal circuits has been suggested. Such impairments imply corresponding oculomotor deficits.Method. Eye movement response to foveofugal and foveopetal step–ramp stimuli was recorded within the same study design in patients with schizophrenia (N=16), affective disorder (N=15), and OCD (N=18) and compared with controls (N=23) using infra-red reflection oculography.Results. In the foveofugal task steady-state velocity was lower in all patient groups compared with controls. Post-saccadic eye velocity was also decreased in patients with schizophrenia and affective disorder. In the foveopetal stimulus steady-state velocity was reduced in schizophrenic patients, only. Changes of saccadic latencies or position errors were not found in any of the patient groups. Also, pursuit latency was unchanged and initial eye acceleration was not decreased.Conclusions. Unaltered saccadic parameters indicate intact motion perception in cortical visual area V5. Therefore, the observed deficit of pursuit maintenance implies a dysfunction of frontal networks in all patient groups including the pursuit region of the frontal eye field (FEF). In patients with schizophrenia and affective disorder reduced post-saccadic pursuit initiation may indicate an impaired interaction between the pursuit and the saccadic system.