An examination of the variables that affect express saccade generation

2004 ◽  
Vol 21 (2) ◽  
pp. 119-127 ◽  
Author(s):  
PETER H. SCHILLER ◽  
JOHANNES HAUSHOFER ◽  
GEOFFERY KENDALL
Keyword(s):  
Rhesus Monkeys ◽  
Target Onset ◽  
Express Saccades ◽  
Express Saccade ◽  
Saccadic System ◽  
Fixation Spot ◽  
Temporal Asynchrony ◽  
Saccade Generation ◽  
Gap Time

The frequency with which express saccades are generated under a variety of conditions in rhesus monkeys was examined. Increasing the gap time between fixation spot termination and target onset increased express saccade frequency but was progressively less effective in doing so as the number of target positions in the sample was increased. Express saccades were rarely produced when two targets were presented simultaneously and the choice of either of which was rewarded; a temporal asynchrony of only 17 ms between the targets reinstated express saccade generation. Express saccades continued to be generated when the vergence or pursuit systems was coactivated with the saccadic system.

Activity of visuomotor burst neurons in the superior colliculus accompanying express saccades

1996 ◽  
Vol 76 (2) ◽  
pp. 908-926 ◽  
Author(s):  
J. A. Edelman ◽  
E. L. Keller
Keyword(s):  
Superior Colliculus ◽  
Critical Role ◽  
Cell Activity ◽  
Saccade Latency ◽  
The Other ◽  
Target Onset ◽  
Express Saccades ◽  
Express Saccade ◽  
Burst Neurons ◽  
Saccade Onset

1. We recorded visuomotor burst neurons in the deeper layers of the superior colliculus while two monkeys (Macaca fascicularis) made short-latency saccades known as express saccades to visual targets in order to determine whether the visual discharge normally seen for these cells served as the premotor burst during express saccades. We then compared saccade-related activity during express saccades with that recorded during regular latency saccades and delayed saccades. 2. Saccade latency histograms for two monkeys during trials with a temporal gap between fixation-point offset and target onset showed a distinct peak of saccades around 70-80 ms. One monkey also showed an additional peak around 125 ms. 3. Express saccades were found on the average to have the same relationship of saccade peak velocity to saccade amplitude as regular latency saccades and delayed saccades. Express saccades tended to be somewhat more hypometric than the other classes of saccades. However, express saccades were clearly visually guided and not anticipatory responses. 4. For most cells studied (33/40), express saccades were accompanied by a single, uninterrupted burst of activity beginning 40-50 ms after target onset and continuing until sometime around the end of the saccade. For a smaller group of cells (7/40), two peaks of burst activity were seen, although the second peak was smaller and tended to occur late, after saccade onset. Across all cells, the peak of visuomotor cell activity during express saccades correlated just as well with target onset as it did with saccade onset. 5. When considered as discharge temporally aligned to the onset of the saccade, bursts accompanying express saccades tended to begin at approximately the same time as that for regular and delayed saccades. However, this discharge generally peaked earlier for express than for regular and delayed saccades. Also, the magnitude of discharge for express saccades was higher than that for delayed saccades throughout the burst. 6. When considered as discharge temporally aligned to the appearance of the target, bursts began earlier for express and regular saccade trials than for delayed saccade trials. Peak discharge tended to be greater for express saccades than for the other classes of saccades. 7. The results of this investigation are consistent with the suggestion that the visual burst of visuomotor neurons in the deeper layers of the superior colliculus plays a role in the initiation of express saccades similar to that played by the premotor burst for saccades of longer latency. The elevated discharge for express saccades supports the idea that the superior colliculus plays a more critical role in express saccade generation than in the generation of longer-latency saccades. The elevated discharge also suggests that visuomotor bursters do not code one-to-one for saccade velocity nor for saccade dynamic motor error.

scholarly journals Impairment but not abolishment of express saccades after unilateral or bilateral inactivation of the frontal eye fields

2020 ◽  
Vol 123 (5) ◽  
pp. 1907-1919 ◽  
Author(s):  
Suryadeep Dash ◽  
Tyler R. Peel ◽  
Stephen G. Lomber ◽  
Brian D. Corneil
Keyword(s):  
Superior Colliculus ◽  
Peak Velocity ◽  
Critical Role ◽  
Frontal Eye Fields ◽  
Express Saccades ◽  
Express Saccade ◽  
Cortical Cooling ◽  
Saccade Generation

Express saccades are the shortest-latency saccade. The frontal eye fields (FEF) are thought to promote express saccades by presetting the superior colliculus. Here, by reversibly inactivating the FEF either unilaterally or bilaterally via cortical cooling, we support this by showing that the FEF plays a facilitative but not critical role in express saccade generation. We also found that FEF inactivation lowered express saccade peak velocity, emphasizing a contribution of the FEF to express saccade kinematics.

scholarly journals The integration of visual and auditory cues for express saccade generation

2010 ◽  
Vol 10 (7) ◽  
pp. 505-505
Author(s):  
P. Schiller ◽  
M. Kwak
Keyword(s):  
Express Saccade ◽  
Auditory Cues ◽  
Saccade Generation

Two attentional components for two purposes

1997 ◽  
Vol 20 (4) ◽  
pp. 770-771
Author(s):  
B. Fischer ◽  
H. Weber
Keyword(s):  
Error Rate ◽  
Express Saccades ◽  
Antisaccade Task ◽  
Voluntary Attention ◽  
Peripheral Location ◽  
Fixation System ◽  
Saccade Generation

Inappropriate saccades are prevented by fixation and by voluntary attention. The fixation system inhibits the saccade system. Like monkeys without a fixation system, humans with a weak fixation system produce many express saccades and cannot suppress prosaccades in an antisaccade task. With permanent attention to a peripheral location only a few express saccades to a stimulus at this location can be elicited: the sustained component of attention acts like fixation. When attention is captured by a precue, more express saccades are obtained: the stimulus-driven component of attention facilitates saccade generation. If the cue correctly indicates the direction for an antisaccade error rate and latencies are increased.

Superior Colliculus Activity Related to Concurrent Processing of Saccade Goals in a Visual Search Task

2002 ◽  
Vol 87 (4) ◽  
pp. 1805-1815 ◽  
Author(s):  
Robert M. McPeek ◽  
Edward L. Keller
Keyword(s):  
Superior Colliculus ◽  
Rhesus Monkeys ◽  
Search Task ◽  
Visual Search Task ◽  
Saccadic System ◽  
Concurrent Processing ◽  
Initial Saccade ◽  
Preparatory Activity ◽  
Winner Take All ◽  
Initial Movement

Saccades are typically separated by inter-saccadic fixation intervals (ISFIs) of ≥125 ms. During this time, the saccadic system selects a goal and completes the preparatory processes required prior to executing the subsequent movement. However, in tasks in which competing stimuli are presented, two sequentially executed movements to different goals can be separated by much shorter ISFIs. This suggests that the saccadic system is capable of completing many of the preparatory requirements for a second saccade concurrently with the execution of an initial movement. We recorded single neurons in the superior colliculus (SC) during rapid saccade sequences made by rhesus monkeys performing a search task. We found that during the execution of an initial saccade, activity related to the goal of a quickly following second saccade can be simultaneously maintained in the SC motor map. This activity appears to signal the selection or increased salience of the second saccade goal even before the initial saccade has ended. For movements separated by normal ISFIs (≥125 ms), we did not observe activity related to concurrent processing, presumably because for these longer ISFI responses, the goal of the second saccade is not selected until after the end of the first saccade. These results indicate that, at the time of an initial saccade, the SC does not necessarily act as a strict winner-take-all network. Rather it appears that the salience of a second visual goal can be simultaneously maintained in the SC. This provides evidence that selection or preparatory activity related to the goal of a second saccade can overlap temporally with activity related to an initial saccade and indicates that such concurrent processing is present even in a structure which is fairly close to the motor output.

Express saccades and visual attention

1993 ◽  
Vol 16 (3) ◽  
pp. 553-567 ◽  
Author(s):  
B. Fischer ◽  
H. Weber
Keyword(s):  
Eye Movements ◽  
Visual Attention ◽  
Reaction Times ◽  
Express Saccades ◽  
Research Groups ◽  
Express Saccade ◽  
Brain Functions ◽  
Target Article ◽  
Higher Brain Functions ◽  
Present Understanding

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.

scholarly journals Express saccades and superior colliculus responses are sensitive to short-wavelength cone contrast

2016 ◽  
Vol 113 (24) ◽  
pp. 6743-6748 ◽  
Author(s):  
Nathan J. Hall ◽  
Carol L. Colby
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Short Wavelength ◽  
Human Subjects ◽  
Reaction Times ◽  
Saccadic Eye Movements ◽  
Express Saccades ◽  
Color Information ◽  
Express Saccade ◽  
Psychophysical Studies

A key structure for directing saccadic eye movements is the superior colliculus (SC). The visual pathways that project to the SC have been reported to carry only luminance information and not color information. Short-wavelength–sensitive cones (S-cones) in the retina make little or no contribution to luminance signals, leading to the conclusion that S-cone stimuli should be invisible to SC neurons. The premise that S-cone stimuli are invisible to the SC has been used in numerous clinical and human psychophysical studies. The assumption that the SC cannot use S-cone stimuli to guide behavior has never been tested. We show here that express saccades, which depend on the SC, can be driven by S-cone input. Further, express saccade reaction times and changes in SC activity depend on the amount of S-cone contrast. These results demonstrate that the SC can use S-cone stimuli to guide behavior. We conclude that the use of S-cone stimuli is insufficient to isolate SC function in psychophysical and clinical studies of human subjects.

Selective impairment of express saccade generation in patients with schizophrenia

1993 ◽  
Vol 97 (2) ◽  
Author(s):  
Jon Currie ◽  
Sarah Joyce ◽  
Paul Maruff ◽  
Ben Ramsden ◽  
Cheryl McArthur-Jackson ◽  
...  
Keyword(s):  
Express Saccade ◽  
Selective Impairment ◽  
Saccade Generation

Dependence on Target Configuration of Express Saccade-Related Activity in the Primate Superior Colliculus

1998 ◽  
Vol 80 (3) ◽  
pp. 1407-1426 ◽  
Author(s):  
Jay A. Edelman ◽  
Edward L. Keller
Keyword(s):  
Superior Colliculus ◽  
Target Selection ◽  
Visual Response ◽  
Express Saccades ◽  
Related Activity ◽  
Express Saccade ◽  
Spatial Properties ◽  
Target Configuration ◽  
Single Target ◽  
Single Burst

Edelman, Jay A. and Edward L. Keller. Dependence on target configuration of express saccade-related activity in the primate superior colliculus. J. Neurophysiol. 80: 1407–1426, 1998. To help understand how complex visual stimuli are processed into short-latency saccade motor programs, the activity of visuomotor neurons in the deeper layers of the superior colliculus was recorded while two monkeys made express saccades to one target and to two targets. It has been shown previously that the visual response and perimotor discharge characteristic of visuomotor neurons temporally coalesce into a single burst of discharge for express saccades. Here we seek to determine whether the distributed visual response to two targets spatially coalesces into a command appropriate for the resulting saccade. Two targets were presented at identical radial eccentricities separated in direction by 45°. A gap paradigm was used to elicit express saccades. Express saccades were more likely to land in between the two targets than were saccades of longer latency. The speeds of express saccades to two targets were similar to those of one target of similar vector, as were the trajectories of saccades to one and two targets. The movement fields for express saccades to two targets were more broad than those for saccades to one target for all neurons studied. For most neurons, the spatial pattern of discharge for saccades to two targets was better explained as a scaled version of the visual response to two spatially separate targets than as a scaled version of the perimotor response accompanying a saccade to a single target. Only the discharge of neurons with large movement fields could be equally well explained as a visual response to two targets or as a perimotor response for a one-target saccade. For most neurons, the spatial properties of discharge depended on the number of targets throughout the entire saccade-related burst. These results suggest that for express saccades to two targets the computation of saccade vector is not complete at the level of the superior colliculus for most neurons and an explicit process of target selection is not necessary at this level for the programming of an express saccade.

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