scholarly journals Coupling Between Horizontal and Vertical Components of Saccadic Eye Movements During Constant Amplitude and Direction Gaze Shifts in the Rhesus Monkey

2008 ◽  
Vol 100 (6) ◽  
pp. 3375-3393 ◽  
Author(s):  
Edward G. Freedman
Keyword(s):  
Eye Movements ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Horizontal Meridian ◽  
Constant Amplitude ◽  
Saccade Amplitude ◽  
Gaze Shifts ◽  
Horizontal Saccade ◽  
Vertical Saccade ◽  
Saccade Duration

When the head is free to move, changes in the direction of the line of sight (gaze shifts) can be accomplished using coordinated movements of the eyes and head. During repeated gaze shifts between the same two targets, the amplitudes of the saccadic eye movements and movements of the head vary inversely as a function of the starting positions of the eyes in the orbits. In addition, as head-movement amplitudes and velocities increase, saccade velocities decline. Taken together these observations lead to a reversal in the expected correlation between saccade duration and amplitude: small-amplitude saccades associated with large head movements can have longer durations than larger-amplitude saccades associated with small head movements. The data in this report indicate that this reversal occurs during gaze shifts along the horizontal meridian and also when considering the horizontal component of oblique saccades made when the eyes begin deviated only along the horizontal meridian. Under these conditions, it is possible to determine whether the variability in the duration of the constant amplitude vertical component of oblique saccades is accounted for better by increases in horizontal saccade amplitude or increases in horizontal saccade duration. Results show that vertical saccade duration can be inversely related to horizontal saccade amplitude (or unrelated to it) but that horizontal saccade duration is an excellent predictor of vertical saccade duration. Modifications to existing hypotheses of gaze control are assessed based on these new observations and a mechanism is proposed that can account for these data.

Subcortical contributions to head movements in macaques. I. Contrasting effects of electrical stimulation of a medial pontomedullary region and the superior colliculus

1994 ◽  
Vol 72 (6) ◽  
pp. 2648-2664 ◽  
Author(s):  
R. J. Cowie ◽  
D. L. Robinson
Keyword(s):  
Electrical Stimulation ◽  
Eye Movements ◽  
Superior Colliculus ◽  
Head Movement ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Reticular Nucleus ◽  
Gaze Shifts ◽  
Gigantocellular Reticular Nucleus ◽  
External Events

1. These studies were initiated to understand the neural sites and mechanisms controlling head movements during gaze shifts. Gaze shifts are made by saccadic eye movements with and without head movements. Sites were stimulated electrically within the brain stem of awake, trained monkeys relatively free to make head movements to study the head-movement components of gaze shifts. 2. Electrical stimulation in and around the gigantocellular reticular nucleus evoked head movements in the ipsilateral direction. Gaze shifts were never evoked from these sites, presumably because the vestibulo-ocular reflex compensated. The rough topography of this region included large head movements laterally, small movements medially, downward movements from dorsal sites, and upward movements more ventrally. 3. The initial position of the head influenced the magnitude of the elicited movement with larger movements produced when the head was directed to the contralateral side. Attentive fixation was associated with larger and faster head movements when compared with those evoked during spontaneous behavior. 4. The superior colliculus makes a significant contribution to gaze shifts and has been shown to contribute to head movements. Because the colliculus is a major source of afferents to the gigantocellular reticular nucleus, comparable stimulation studies of the superior colliculus were conducted. When the colliculus was excited, shifts of gaze in the contralateral direction were predominant. These were most often accomplished by saccadic eye movements, however, we frequently elicited head movements that had an average latency 10 ms longer than those elicited from the reticular head movement region. Sites evoking head movements tended to be deeper and more caudal than loci eliciting eye movements. Neither the onset latencies, amplitudes, nor peak velocities of head movements and eye movements were correlated. Gaze shifts evoked from the caudal colliculus with the head free were larger than those elicited from the same site with the head fixed. 5. These studies demonstrate that both the superior colliculus and gigantocellular reticular nucleus mediate head movements. The colliculus plays a role in orienting to external events, and so collicular head movements predominantly were associated with gaze shifts, with the eye and head movements uncoupled. The medullary reticular system may play a role in the integration of a wider range of movements. Head movements from the medullary reticular sites probably participate in several forms of head movements, such as those that are related to postural reflexes, started volitionally, and/or oriented to external events.

Contribution of the Frontal Eye Field to Gaze Shifts in the Head-Unrestrained Monkey: Effects of Microstimulation

2007 ◽  
Vol 97 (1) ◽  
pp. 618-634 ◽  
Author(s):  
Thomas A. Knight ◽  
Albert F. Fuchs
Keyword(s):  
Eye Movements ◽  
Stimulus Duration ◽  
Head Movement ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Frontal Eye Field ◽  
Threshold Region ◽  
Gaze Shifts ◽  
Eye Field ◽  
Orbital Position

The role of the primate frontal eye field (FEF) has been inferred primarily from experiments investigating saccadic eye movements with the head restrained. Three recent reports investigating head-unrestrained gaze shifts disagree on whether head movements are evoked with FEF stimulation and thus whether the FEF participates in gaze movement commands. We therefore examined the eye, head, and overall gaze movement evoked by low-intensity microstimulation of the low-threshold region of the FEF in two head-unrestrained monkeys. Microstimulation applied at 200 or 350 Hz for 200 ms evoked large gaze shifts with substantial head movement components from most sites in the dorsomedial FEF, but evoked small, predominantly eye-only gaze shifts from ventrolateral sites. The size and direction of gaze and eye movements were strongly affected by the eye position before stimulation. Head movements exhibited little position dependency, but at some sites and initial eye positions, head-only movements were evoked. Stimulus-evoked gaze shifts and their eye and head components resembled those elicited naturally by visual targets. With stimulus train durations >200 ms, the evoked gaze shifts were more likely to be accomplished with a substantial head movement, which often continued for the entire stimulus duration. The amplitude, duration and peak velocity of the evoked head movement were more strongly correlated with stimulus duration than were those of the gaze or eye movements. We conclude that the dorsomedial FEF generates a gaze command signal that can produce eye, head, or combined eye–head movement depending on the initial orbital position of the eye.

Sound-Localization Performance in the Cat: The Effect of Restraining the Head

2005 ◽  
Vol 93 (3) ◽  
pp. 1223-1234 ◽  
Author(s):  
Daniel J. Tollin ◽  
Luis C. Populin ◽  
Jordan M. Moore ◽  
Janet L. Ruhland ◽  
Tom C. T. Yin
Keyword(s):  
Short Duration ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Gaze Shifts ◽  
Localization Accuracy ◽  
Head Restraint ◽  
The Gaze ◽  
Long Duration ◽  
Localization Performance ◽  
Visual Targets

In oculomotor research, there are two common methods by which the apparent location of visual and/or auditory targets are measured, saccadic eye movements with the head restrained and gaze shifts (combined saccades and head movements) with the head unrestrained. Because cats have a small oculomotor range (approximately ±25°), head movements are necessary when orienting to targets at the extremes of or outside this range. Here we tested the hypothesis that the accuracy of localizing auditory and visual targets using more ethologically natural head-unrestrained gaze shifts would be superior to head-restrained eye saccades. The effect of stimulus duration on localization accuracy was also investigated. Three cats were trained using operant conditioning with their heads initially restrained to indicate the location of auditory and visual targets via eye position. Long-duration visual targets were localized accurately with little error, but the locations of short-duration visual and both long- and short-duration auditory targets were markedly underestimated. With the head unrestrained, localization accuracy improved substantially for all stimuli and all durations. While the improvement for long-duration stimuli with the head unrestrained might be expected given that dynamic sensory cues were available during the gaze shifts and the lack of a memory component, surprisingly, the improvement was greatest for the auditory and visual stimuli with the shortest durations, where the stimuli were extinguished prior to the onset of the eye or head movement. The underestimation of auditory targets with the head restrained is explained in terms of the unnatural sensorimotor conditions that likely result during head restraint.

Distributed spatial coding in the superior colliculus: A review

1991 ◽  
Vol 6 (1) ◽  
pp. 3-13 ◽  
Author(s):  
James T. McIlwain
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Receptive Fields ◽  
Saccadic Eye Movements ◽  
Visual Direction ◽  
Saccade Amplitude ◽  
Spatial Coding ◽  
Distributed Coding

AbstractThis paper reviews evidence that the superior colliculus (SC) of the midbrain represents visual direction and certain aspects of saccadic eye movements in the distribution of activity across a population of cells. Accurate and precise eye movements appear to be mediated, in part at least, by cells of the SC that have large sensory receptive fields and/or discharge in association with a range of saccades. This implies that visual points or saccade targets are represented by patches rather than points of activity in the SC. Perturbation of the pattern of collicular discharge by focal inactivation modifies saccade amplitude and direction in a way consistent with distributed coding. Several models have been advanced to explain how such a code might be implemented in the colliculus. Evidence related to these hypotheses is examined and continuing uncertainties are identified.

scholarly journals Electrical Stimulation of the Frontal Eye Field in a Monkey Produces Combined Eye and Head Movements

2000 ◽  
Vol 84 (2) ◽  
pp. 1103-1106 ◽  
Author(s):  
Tyson A. Tu ◽  
E. Gregory Keating
Keyword(s):  
Electrical Stimulation ◽  
Eye Movements ◽  
Head Movements ◽  
Frontal Eye Field ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
Eye Field ◽  
A Site ◽  
Head Rotations ◽  
Stimulation Of

The frontal eye field (FEF), an area in the primate frontal lobe, has long been considered important for the production of eye movements. Past studies have evoked saccade-like movements from the FEF using electrical stimulation in animals that were not allowed to move their heads. Using electrical stimulation in two monkeys that were free to move their heads, we have found that the FEF produces gaze shifts that are composed of both eye and head movements. Repeated stimulation at a site evoked gaze shifts of roughly constant amplitude. However, that gaze shift could be accomplished with varied amounts of head and eye movements, depending on their (head and eye) respective starting positions. This evidence suggests that the FEF controls visually orienting movements using both eye and head rotations rather than just shifting the eyes as previously thought.

scholarly journals Target modality determines eye-head coordination in nonhuman primates: implications for gaze control

2011 ◽  
Vol 106 (4) ◽  
pp. 2000-2011 ◽  
Author(s):  
Luis C. Populin ◽  
Abigail Z. Rajala
Keyword(s):  
Nonhuman Primates ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
The Gaze ◽  
Midbrain Structure ◽  
The Subject ◽  
Visual Targets ◽  
Time Of Presentation

We have studied eye-head coordination in nonhuman primates with acoustic targets after finding that they are unable to make accurate saccadic eye movements to targets of this type with the head restrained. Three male macaque monkeys with experience in localizing sounds for rewards by pointing their gaze to the perceived location of sources served as subjects. Visual targets were used as controls. The experimental sessions were configured to minimize the chances that the subject would be able to predict the modality of the target as well as its location and time of presentation. The data show that eye and head movements are coordinated differently to generate gaze shifts to acoustic targets. Chiefly, the head invariably started to move before the eye and contributed more to the gaze shift. These differences were more striking for gaze shifts of <20–25° in amplitude, to which the head contributes very little or not at all when the target is visual. Thus acoustic and visual targets trigger gaze shifts with different eye-head coordination. This, coupled to the fact that anatomic evidence involves the superior colliculus as the link between auditory spatial processing and the motor system, suggests that separate signals are likely generated within this midbrain structure.

scholarly journals Saccadic eye movements are coordinated with head movements in walking chickens

1982 ◽  
Vol 97 (1) ◽  
pp. 217-223
Author(s):  
D. W. Pratt
Keyword(s):  
Eye Movements ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Clear Vision ◽  
Head Bobbing ◽  
Insufficient Time ◽  
Made In

1. Saccadic eye movements during walking were studied in chickens using cinematography. 2. Saccades were made during about 80% of the thrust phases of head bobbing, and not made in the hold phases. 3. The coordination of saccades with head movements maintains clear vision for the largest possible proportion of the time. 4. The absence of saccades in hold phases and in some thrusts is probably not the result of insufficient time to organize a saccade.

Eye-head coordination in cats

1984 ◽  
Vol 52 (6) ◽  
pp. 1030-1050 ◽  
Author(s):  
D. Guitton ◽  
R. M. Douglas ◽  
M. Volle
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Head Movement ◽  
Maximum Velocity ◽  
Head Movements ◽  
Visual Axis ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
Rapid Eye Movements ◽  
Motor Strategy

Gaze is the position of the visual axis in space and is the sum of the eye movement relative to the head plus head movement relative to space. In monkeys, a gaze shift is programmed with a single saccade that will, by itself, take the eye to a target, irrespective of whether the head moves. If the head turns simultaneously, the saccade is correctly reduced in size (to prevent gaze overshoot) by the vestibuloocular reflex (VOR). Cats have an oculomotor range (OMR) of only about +/- 25 degrees, but their field of view extends to about +/- 70 degrees. The use of the monkey's motor strategy to acquire targets lying beyond +/- 25 degrees requires the programming of saccades that cannot be physically made. We have studied, in cats, rapid horizontal gaze shifts to visual targets within and beyond the OMR. Heads were either totally unrestrained or attached to an apparatus that permitted short unexpected perturbations of the head trajectory. Qualitatively, similar rapid gaze shifts of all sizes up to at least 70 degrees could be accomplished with the classic single-eye saccade and a saccade-like head movement. For gaze shifts greater than 30 degrees, this classic pattern frequently was not observed, and gaze shifts were accomplished with a series of rapid eye movements whose time separation decreased, frequently until they blended into each other, as head velocity increased. Between discrete rapid eye movements, gaze continued in constant velocity ramps, controlled by signals added to the VOR-induced compensatory phase that followed a saccade. When the head was braked just prior to its onset in a 10 degrees gaze shift, the eye attained the target. This motor strategy is the same as that reported for monkeys. However, for larger target eccentricities (e.g., 50 degrees), the gaze shift was interrupted by the brake and the average saccade amplitude was 12-15 degrees, well short of the target and the OMR. Gaze shifts were completed by vestibularly driven eye movements when the head was released. Braking the head during either quick phases driven by passive head displacements or visually triggered saccades resulted in an acceleration of the eye, thereby implying interaction between the VOR and these rapid-eye-movement signals. Head movements possessed a characteristic but task-dependent relationship between maximum velocity and amplitude. Head movements terminated with the head on target. The eye saccade usually lagged the head displacement.(ABSTRACT TRUNCATED AT 400 WORDS)

Eye position effects in saccadic adaptation

2011 ◽  
Vol 106 (5) ◽  
pp. 2536-2545 ◽  
Author(s):  
Katharina Havermann ◽  
Eckart Zimmermann ◽  
Markus Lappe
Keyword(s):  
Eye Movements ◽  
Visual Space ◽  
Initial Position ◽  
Head Movements ◽  
Eye Position ◽  
Saccade Amplitude ◽  
Position Effects ◽  
Position Information ◽  
Saccadic Adaptation ◽  
Visual Error

Saccades are used by the visual system to explore visual space with the high accuracy of the fovea. The visual error after the saccade is used to adapt the control of subsequent eye movements of the same amplitude and direction in order to keep saccades accurate. Saccadic adaptation is thus specific to saccade amplitude and direction. In the present study we show that saccadic adaptation is also specific to the initial position of the eye in the orbit. This is useful, because saccades are normally accompanied by head movements and the control of combined head and eye movements depends on eye position. Many parts of the saccadic system contain eye position information. Using the intrasaccadic target step paradigm, we adaptively reduced the amplitude of reactive saccades to a suddenly appearing target at a selective position of the eyes in the orbitae and tested the resulting amplitude changes for the same saccade vector at other starting positions. For central adaptation positions the saccade amplitude reduction transferred completely to eccentric starting positions. However, for adaptation at eccentric starting positions, there was a reduced transfer to saccades from central starting positions or from eccentric starting positions in the opposite hemifield. Thus eye position information modifies the transfer of saccadic amplitude changes in the adaptation of reactive saccades. A gain field mechanism may explain the eye position dependence found.

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