Head Movement Evoked By Electrical Stimulation in the Supplementary Eye Field of the Rhesus Monkey

2005 ◽  
Vol 94 (6) ◽  
pp. 4502-4519 ◽  
Author(s):  
L. Longtang Chen ◽  
Mark M. G. Walton
Keyword(s):  
Head Movement ◽  
Direct Evidence ◽  
Head Movements ◽  
Eye Position ◽  
Low Velocity ◽  
Gaze Shifts ◽  
The Gaze ◽  
Supplementary Eye Field ◽  
Combined Movements ◽  
Eye Field

Although the supplementary eye field (SEF) has been implicated in the control of head movements associated with gaze shifts, there is no direct evidence that SEF plays a role in the generation of head movements independent of gaze. If the SEF does, varying the duration of stimulation should selectively alter the head-movement kinematics during the postgaze-shift period. The duration of the stimulation was manipulated while head-unrestrained monkeys maintained stable head forward postures. The initial positions of the eyes in the orbits were systematically varied. Although combined movements of the eyes and head were produced in the majority of the trials, head movements were sometimes evoked in the absence of gaze shifts. These head-alone movements were most frequent when the initial eye position was contralateral to the stimulated side. When the stimulation produced eye and head movements, gaze onset was sometimes preceded by a relatively low-velocity phase of the head movement. Evoked head movements were primarily horizontal, unlike the gaze shifts, which typically had vertical components that varied according to the initial positions of the eyes in the orbits. The postgaze-shift head movements tended to be of low velocity and in many cases persisted until stimulation offset. In general, prolonging the stimulation resulted in improved centering of the eyes in the orbits. These findings suggest that, in addition to its previously described role in the generation of coordinated eye-head gaze shifts, the SEF is also involved in the control of head movements in the absence of a change of gaze.

Rapid horizontal gaze movement in the monkey

1995 ◽  
Vol 73 (4) ◽  
pp. 1632-1652 ◽  
Author(s):  
J. O. Phillips ◽  
L. Ling ◽  
A. F. Fuchs ◽  
C. Siebold ◽  
J. J. Plorde
Keyword(s):  
Eye Movement ◽  
Head Movement ◽  
Vertical Axis ◽  
Head Position ◽  
Head Movements ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
The Gaze ◽  
Small Correction ◽  
Horizontal Gaze

1. We studied horizontal eye and head movements in three monkeys that were trained to direct their gaze (eye position in space) toward jumping targets while their heads were both fixed and free to rotate about a vertical axis. We considered all gaze movements that traveled > or = 80% of the distance to the new visual target. 2. The relative contributions and metrics of eye and head movements to the gaze shift varied considerably from animal to animal and even within animals. Head movements could be initiated early or late and could be large or small. The eye movements of some monkeys showed a consistent decrease in velocity as the head accelerated, whereas others did not. Although all gaze shifts were hypometric, they were more hypometric in some monkeys than in others. Nevertheless, certain features of the gaze shift were identifiable in all monkeys. To identify those we analyzed gaze, eye in head position, and head position, and their velocities at three points in time during the gaze shift: 1) when the eye had completed its initial rotation toward the target, 2) when the initial gaze shift had landed, and 3) when the head movement was finished. 3. For small gaze shifts (< 20 degrees) the initial gaze movement consisted entirely of an eye movement because the head did not move. As gaze shifts became larger, the eye movement contribution saturated at approximately 30 degrees and the head movement contributed increasingly to the initial gaze movement. For the largest gaze shifts, the eye usually began counterrolling or remained stable in the orbit before gaze landed. During the interval between eye and gaze end, the head alone carried gaze to completion. Finally, when the head movement landed, it was almost aimed at the target and the eye had returned to within 10 +/- 7 degrees, mean +/- SD, of straight ahead. Between the end of the gaze shift and the end of the head movement, gaze remained stable in space or a small correction saccade occurred. 4. Gaze movements < 20 degrees landed accurately on target whether the head was fixed or free. For larger target movements, both head-free and head-fixed gaze shifts became increasingly hypometric. Head-free gaze shifts were more accurate, on average, but also more variable. This suggests that gaze is controlled in a different way with the head free. For target amplitudes < 60 degrees, head position was hypometric but the error was rather constant at approximately 10 degrees.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Dissociation of Eye and Head Components of Gaze Shifts by Stimulation of the Omnipause Neuron Region

2007 ◽  
Vol 98 (1) ◽  
pp. 360-373 ◽  
Author(s):  
Neeraj J. Gandhi ◽  
David L. Sparks
Keyword(s):  
Head Movement ◽  
Displacement Vector ◽  
Movement Control ◽  
Head Movements ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
The Gaze ◽  
Movement Component ◽  
Neck Motoneurons ◽  
Stimulation Of

Natural movements often include actions integrated across multiple effectors. Coordinated eye-head movements are driven by a command to shift the line of sight by a desired displacement vector. Yet because extraocular and neck motoneurons are separate entities, the gaze shift command must be separated into independent signals for eye and head movement control. We report that this separation occurs, at least partially, at or before the level of pontine omnipause neurons (OPNs). Stimulation of the OPNs prior to and during gaze shifts temporally decoupled the eye and head components by inhibiting gaze and eye saccades. In contrast, head movements were consistently initiated before gaze onset, and ongoing head movements continued along their trajectories, albeit with some characteristic modulations. After stimulation offset, a gaze shift composed of an eye saccade, and a reaccelerated head movement was produced to preserve gaze accuracy. We conclude that signals subject to OPN inhibition produce the eye-movement component of a coordinated eye-head gaze shift and are not the only signals involved in the generation of the head component of the gaze shift.

Action of the Brain Stem Saccade Generator During Horizontal Gaze Shifts. I. Discharge Patterns of Omnidirectional Pause Neurons

1999 ◽  
Vol 81 (3) ◽  
pp. 1284-1295 ◽  
Author(s):  
James O. Phillips ◽  
Leo Ling ◽  
Albert F. Fuchs
Keyword(s):  
Brain Stem ◽  
Eye Movement ◽  
Head Movement ◽  
Head Movements ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
The Gaze ◽  
Horizontal Gaze ◽  
Discharge Patterns ◽  
The Brain

Action of the brain stem saccade generator during horizontal gaze shifts. I. Discharge patterns of omnidirectional pause neurons. Omnidirectional pause neurons (OPNs) pause for the duration of a saccade in all directions because they are part of the neural mechanism that controls saccade duration. In the natural situation, however, large saccades are accompanied by head movements to produce rapid gaze shifts. To determine whether OPNs are part of the mechanism that controls the whole gaze shift rather than the eye saccade alone, we monitored the activity of 44 OPNs that paused for rightward and leftward gaze shifts but otherwise discharged at relatively constant average rates. Pause duration was well correlated with the duration of either eye or gaze movement but poorly correlated with the duration of head movement. The time of pause onset was aligned tightly with the onset of either eye or gaze movement but only loosely aligned with the onset of head movement. These data suggest that the OPN pause does not encode the duration of head movement. Further, the end of the OPN pause was often better aligned with the end of the eye movement than with the end of the gaze movement for individual gaze shifts. For most gaze shifts, the eye component ended with an immediate counterrotation owing to the vestibuloocular reflex (VOR), and gaze ended at variable times thereafter. In those gaze shifts where eye counterrotation was delayed, the end of the pause also was delayed. Taken together, these data suggest that the end of the pause influences the onset of eye counterrotation, not the end of the gaze shift. We suggest that OPN neurons act to control only that portion of the gaze movement that is commanded by the eye burst generator. This command is expressed by driving the saccadic eye movement directly and also by suppressing VOR eye counterrotation. Because gaze end is less well correlated with pause end and often occurs well after counterrotation onset, we conclude that elements of the burst generator typically are not active till gaze end, and that gaze end is determined by another mechanism independent of the OPNs.

Eye-Head Coordination During Head-Unrestrained Gaze Shifts in Rhesus Monkeys

1997 ◽  
Vol 77 (5) ◽  
pp. 2328-2348 ◽  
Author(s):  
Edward G. Freedman ◽  
David L. Sparks
Keyword(s):  
Head Movement ◽  
Rhesus Monkeys ◽  
Initial Position ◽  
Head Movements ◽  
Gaze Shifts ◽  
Unit Recording ◽  
Gaze Shift ◽  
The Gaze ◽  
Two Factors ◽  
Eye Velocity

Freedman, Edward G. and David L. Sparks. Eye-head coordination during head-unrestrained gaze shifts in rhesus monkeys. J. Neurophysiol. 77: 2328–2348, 1997. We analyzed gaze shifts made by trained rhesus monkeys with completely unrestrained heads during performance of a delayed gaze shift task. Subjects made horizontal, vertical, and oblique gaze shifts to visual targets. We found that coordinated eye-head movements are characterized by a set of lawful relationships, and that the initial position of the eyes in the orbits and the direction of the gaze shift are two factors that influence these relationships. Head movements did not contribute to the change in gaze position during small gaze shifts (<20°) directed along the horizontal meridian, when the eyes were initially centered in the orbits. For larger gaze shifts (25–90°), the head contribution to the gaze shift increased linearly with increasing gaze shift amplitude, and eye movement amplitude saturated at an asymptotic amplitude of ∼35°. When the eyes began deviated in the orbits contralateral to the direction of the ensuing gaze shift, the head contributed less and the eyes more to amplitude-matched gaze shifts. The relative timing of eye and head movements was altered by initial eye position; head latency relative to gaze onset increased as the eyes began in more contralateral initial positions. The direction of the gaze shift also affected the relative amplitudes of eye and head movements; as gaze shifts were made in progressively more vertical directions, eye amplitude increased and head contribution declined systematically. Eye velocity was a saturating function of gaze amplitude for movements without a head contribution (gaze amplitude <20°). As head contribution increased with increasing gaze amplitude (20–60°), peak eye velocity declined by >200°/s and head velocity increased by 100°/s. For constant-amplitude eye movements (∼30°), eye velocity declined as the velocity of the concurrent head movement increased. On the basis of these relationships, it is possible to accurately predict gaze amplitude, the amplitudes of the eye and head components of the gaze shift, and gaze, eye, and head velocities, durations and latencies if the two-dimensional displacement of the target and the initial position of the eyes in the orbits are known. These data indicate that signals related to the initial positions of the eyes in the orbits and the direction of the gaze shift influence separate eye and head movement commands. The hypothesis that this divergence of eye and head commands occurs downstream from the superior colliculus is supported by recent electrical stimulation and single-unit recording data.

Combined eye-head gaze shifts in the primate. III. Contributions to the accuracy of gaze saccades

1990 ◽  
Vol 64 (6) ◽  
pp. 1873-1891 ◽  
Author(s):  
R. D. Tomlinson
Keyword(s):  
Head Movement ◽  
Head Movements ◽  
Whole Body ◽  
Midsagittal Plane ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
The Gaze ◽  
Gaze Stability ◽  
Gaze Saccade ◽  
Gaze Saccades

1. The behavior of the combined eye-head gaze saccade mechanism was investigated in the rhesus monkey under both normal circumstances and in the presence of perturbations delivered to the head by a torque motor. Animals were trained to follow a target light that stepped at regular intervals through an angle of 68 degrees (+/- 34 degrees with respect to the midsagittal plane). Thus all primary saccades were center crossing. On randomly occurring trials the torque motor was pulsed so as to perturb the trajectory of the head, thus allowing us to assess both the functional state of the vestibuloocular reflex (VOR) and the effects of such perturbations on gaze saccade accuracy (gaze is defined as the sum of eye-in-head plus head-in-space, and a gaze saccade as a combined eye-head saccadic gaze shift). 2. Gaze shifts can be divided into two discrete sections: the portion during which the gaze angle is changing (the saccadic portion), and the portion during which the gaze is stationary but the head continues to move (the terminal head-movement portion). For the system to accurately acquire eccentric targets, at least two criteria must be met: 1) the saccadic portion must be accurate, and 2) the compensatory eye movement that occurs during the terminal head-movement portion must be equal and opposite to the head movement, thereby maintaining gaze stability. Perturbations delivered during the terminal head-movement portion of the gaze shift indicated that VOR was functioning normally, and thus we concluded that the compensatory eye movements that accompany head movements were vestibular in origin. 3. As reported previously, during the saccadic portion of large-amplitude gaze saccades, the VOR ceases to function. In spite of this observation, the accuracy of the gaze saccade is not affected by perturbations delivered to the head. Gaze accuracy is maintained both by changing the duration of the saccadic portion and by altering the head trajectory. 4. Because rhesus monkeys often make very rapid head movements (1,200 degrees/s), we wished to discover the velocity range over which the monkey VOR might be expected to operate. Accordingly, in a second series of experiments, VOR function was assessed during passive whole-body rotations with the head fixed. By the use of spring-assisted manual rotations, peak velocities up to 850 degrees/s were achieved. When VOR gain was measured during such rotations, it was found to be equal to 0.9 up to the maximum velocities used.(ABSTRACT TRUNCATED AT 400 WORDS)

Role of Superior Colliculus in Adaptive Eye–Head Coordination During Gaze Shifts

2004 ◽  
Vol 92 (4) ◽  
pp. 2168-2184 ◽  
Author(s):  
Alina G. Constantin ◽  
Hongying Wang ◽  
J. Douglas Crawford
Keyword(s):  
Superior Colliculus ◽  
Brain Stem ◽  
Head Movement ◽  
Motor Output ◽  
Eye Position ◽  
Spatial Coding ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
The Gaze ◽  
Context Dependent

The goal of this study was to determine which aspects of adaptive eye–head coordination are implemented upstream or downstream from the motor output layers of the superior colliculus (SC). Two monkeys were trained to perform head-free gaze shifts while looking through a 10° aperture in opaque, head-fixed goggles. This training produced context-dependent alterations in eye–head coordination, including a coordinated pattern of saccade–vestibuloocular reflex (VOR) eye movements that caused eye position to converge toward the aperture, and an increased contribution of head movement to the gaze shift. One would expect the adaptations that were implemented downstream from the SC to be preserved in gaze shifts evoked by SC stimulation. To test this, we analyzed gaze shifts evoked from 19 SC sites in monkey 1 and 38 sites in monkey 2, both with and without goggles. We found no evidence that the goggle paradigm altered the basic gaze position–dependent spatial coding of the evoked movements (i.e., gaze was still coded in an eye-centered frame). However, several aspects of the context-dependent coordination strategy were preserved during stimulation, including the adaptive convergence of final eye position toward the goggles aperture, and the position-dependent patterns of eye and head movement required to achieve this. For example, when initial eye position was offset from the learned aperture location at the time of stimulation, a coordinated saccade–VOR eye movement drove it back to the original aperture, and the head compensated to preserve gaze kinematics. Some adapted amplitude–velocity relationships in eye, gaze, and head movement also may have been preserved. In contrast, context-dependent changes in overall eye and head contribution to gaze amplitude were not preserved during SC stimulation. We conclude that 1) the motor output command from the SC to the brain stem can be adapted to produce different position-dependent coordination strategies for different behavioral contexts, particularly for eye-in-head position, but 2) these brain stem coordination mechanisms implement only the default (normal) level of head amplitude contribution to the gaze shift. We propose that a parallel cortical drive, absent during SC stimulation, is required to adjust the overall head contribution for different behavioral contexts.

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.

Evidence for a supplementary eye field

1987 ◽  
Vol 57 (1) ◽  
pp. 179-200 ◽  
Author(s):  
J. Schlag ◽  
M. Schlag-Rey
Keyword(s):  
Unit Activity ◽  
Cortical Neurons ◽  
Cortical Area ◽  
Head Movements ◽  
Frontal Eye Field ◽  
Unit Recording ◽  
Electrical Microstimulation ◽  
Preferred Direction ◽  
Supplementary Eye Field ◽  
Eye Field

Electrical microstimulation and unit recording were performed in dorsomedial frontal cortex of four alert monkeys to identify an oculomotor area whose existence had been postulated rostral to the supplementary motor area. Contraversive saccades were evoked from 129 sites by stimulation. Threshold currents were lower than 20 microA in half the tests. Response latencies were usually longer than 50 ms (minimum: 30 ms). Eye movements were occasionally accompanied by blinks, ear, or neck movements. The cortical area yielding these movements was at the superior edge of the frontal lobe just rostral to the region from which limb movements could be elicited. Depending on the site of stimulation, saccades varied between two extremes: from having rather uniform direction and size, to converging toward a goal defined in space. The transition between these extremes was gradual with no evidence that these two types were fundamentally different. From surface to depth of cortex, direction and amplitude of evoked saccades were similar or changed progressively. No clear systematization was found depending on location along rostrocaudal or mediolateral axes of the cortex. The dorsomedial oculomotor area mapped was approximately 7 mm long and 6 mm wide. Combined eye and head movements were elicited from one of ten sites stimulated when the head was unrestrained. In the other nine cases, saccades were not accompanied by head rotation, even when higher currents or longer stimulus trains were applied. Presaccadic unit activity was recorded from 62 cells. Each of these cells had a preferred direction that corresponded to the direction of the movement evoked by local microstimulation. Presaccadic activity occurred with self-initiated as well as visually triggered saccades. It often led self-initiated saccades by more than 300 ms. Recordings made with the head free showed that the firing could not be interpreted as due to attempted head movements. Many dorsomedial cortical neurons responded to photic stimuli, either phasically or tonically. Sustained responses (activation or inhibition) were observed during target fixation. Twenty-one presaccadic units showed tonic changes of activity with fixation. Justification is given for considering the cortical area studied as a supplementary eye field. It shares many common properties with the arcuate frontal eye field. Differences noted in this study include: longer latency of response to electrical stimulation, possibility to evoke saccades converging apparently toward a goal, and long-lead unit activity with spontaneous saccades.

Head-Unrestrained Gaze Shifts After Muscimol Injection in the Caudal Fastigial Nucleus of the Monkey

2007 ◽  
Vol 98 (6) ◽  
pp. 3269-3283 ◽  
Author(s):  
Julie Quinet ◽  
Laurent Goffart
Keyword(s):  
Feedback Control ◽  
Head Movement ◽  
Peak Velocity ◽  
Head Movements ◽  
Fastigial Nucleus ◽  
Gaze Shifts ◽  
Movement Accuracy ◽  
Central Target ◽  
Target Eccentricity ◽  
Vertical Gaze

The effects of unilateral cFN inactivation on horizontal and vertical gaze shifts generated from a central target toward peripheral ones were tested in two head unrestrained monkeys. After muscimol injection, the eye component was hypermetric during ipsilesional gaze shifts, hypometric during contralesional ones and deviated toward the injected side during vertical gaze shifts. The ipsilesional gaze hypermetria increased with target eccentricity until ∼24° after which it diminished and became smaller than the hypermetria of the eye component. Contrary to eye saccades, the amplitude and peak velocity of which were enhanced, the amplitude and peak velocity of head movements were reduced during ipsilesional gaze shifts. These changes in head movement were not correlated with those affecting the eye saccades. Head movements were also delayed relative to the onset of eye saccades. The alterations in head movement and the faster eye saccades likely explained the reduced head contribution to the amplitude of ipsilesional gaze shifts. The contralesional gaze hypometria increased with target eccentricity and was associated with uncorrelated reductions in eye and head peak velocities. When compared with control movements of similar amplitude, contralesional eye saccades had lower peak velocity and longer duration. This slowing likely accounted for the increase in head contribution to the amplitude of contralesional gaze shifts. These data suggest different pathways for the fastigial control of eye and head components during gaze shifts. Saccade dysmetria was not compensated by appropriate changes in head contribution, raising the issue of the feedback control of movement accuracy during combined eye-head gaze shifts.

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