Overlap of Saccadic and Pursuit Eye Movement Systems in the Brain Stem Reticular Formation

2001 ◽  
Vol 86 (6) ◽  
pp. 3056-3060 ◽  
Author(s):  
Yi-Jun Yan ◽  
Dong-Mei Cui ◽  
James C. Lynch
Keyword(s):  
Eye Movements ◽  
Brain Stem ◽  
Eye Movement ◽  
Saccadic Eye Movements ◽  
Point Of View ◽  
Medial Longitudinal Fasciculus ◽  
Frontal Eye Field ◽  
Neural Pathways ◽  
Eye Field ◽  
The Brain

Recent physiological studies have suggested that there are several sites of interaction between the neural pathways that control saccadic eye movements and those that control visual pursuit movements. To address the question of saccade/pursuit interaction from a neuroanatomical point of view, we have studied the connections from the smooth and saccadic eye movement subregions of the frontal eye field (FEFsem and FEFsac, respectively) to the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) in four Cebus apella monkeys. The riMLF has traditionally been considered to be a premotor center for vertical saccadic eye movements on the basis of single neuron recording experiments, microstimulation experiments, and surgical or chemical lesion experiments. We localized the functional subregions of the FEF with the use of low-threshold (≤50 μA) intracortical microstimulation. Biotinylated dextran amine or lectin from triticum vulgaris (wheat germ), peroxidase labeled, was placed into these functionally defined subregions to label anterogradely the terminals of axons that originated in the FEF. Our results demonstrate that both the FEFsem and FEFsac send direct projections to the ipsilateral riMLF. The distribution and density of labeling from the FEFsem are comparable to those from the FEFsac. The direct FEFsem-to-riMLF projection suggests a possible role of the riMLF in smooth pursuit eye movements and supports the hypothesis that there is interaction between the saccadic and pursuit subsystems at the brain stem level.

scholarly journals Spatio-temporal Brain Dynamics Underlying Saccade Execution, Suppression, and Error-related Feedback

2007 ◽  
Vol 19 (3) ◽  
pp. 420-432 ◽  
Author(s):  
Anthony T. Herdman ◽  
Jennifer D. Ryan
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Saccadic Eye Movements ◽  
Frontal Eye Field ◽  
Neural Responses ◽  
Eye Field ◽  
On Line ◽  
Spatio Temporal ◽  
Neural Underpinnings ◽  
Empirical Demonstration

Human and nonhuman animal research has outlined the neural regions that support saccadic eye movements. The aim of the current work was to outline the sequence by which distinct neural regions come on-line to support goal-directed saccade execution and error-related feedback. To achieve this, we obtained behavioral responses via eye movement recordings and neural responses via magnetoencephalography (MEG), concurrently, while participants performed an antisaccade task. Neural responses were examined with respect to the onset of the saccadic eye movements. Frontal eye field and visual cortex activity distinguished subsequently successful goal-directed saccades from (correct and erroneous) reflexive saccades prior to the deployment of the eye movement. Activity in the same neural regions following the saccadic movement distinguished correct from incorrect saccadic responses. Error-related activity in the frontal eye fields preceded that from visual regions, suggesting a potential feedback network that may drive corrective eye movements. This work provides the first empirical demonstration of simultaneous remote eyetracking and MEG recording. The coupling of behavioral and neuroimaging technologies, used here to characterize dynamic brain networks underlying saccade execution and error-related feedback, demonstrates a novel within-paradigm converging evidence approach by which to outline the neural underpinnings of cognition.

The Brain Stem Saccadic Burst Generator Encodes Gaze in Three-Dimensional Space

2008 ◽  
Vol 99 (5) ◽  
pp. 2602-2616 ◽  
Author(s):  
Marion R. Van Horn ◽  
Pierre A. Sylvestre ◽  
Kathleen E. Cullen
Keyword(s):  
Eye Movements ◽  
Brain Stem ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Saccadic Eye Movements ◽  
Three Dimensions ◽  
Related Information ◽  
Computer Based ◽  
Different Depths ◽  
The Brain

When we look between objects located at different depths the horizontal movement of each eye is different from that of the other, yet temporally synchronized. Traditionally, a vergence-specific neuronal subsystem, independent from other oculomotor subsystems, has been thought to generate all eye movements in depth. However, recent studies have challenged this view by unmasking interactions between vergence and saccadic eye movements during disconjugate saccades. Here, we combined experimental and modeling approaches to address whether the premotor command to generate disconjugate saccades originates exclusively in “vergence centers.” We found that the brain stem burst generator, which is commonly assumed to drive only the conjugate component of eye movements, carries substantial vergence-related information during disconjugate saccades. Notably, facilitated vergence velocities during disconjugate saccades were synchronized with the burst onset of excitatory and inhibitory brain stem saccadic burst neurons (SBNs). Furthermore, the time-varying discharge properties of the majority of SBNs (>70%) preferentially encoded the dynamics of an individual eye during disconjugate saccades. When these experimental results were implemented into a computer-based simulation, to further evaluate the contribution of the saccadic burst generator in generating disconjugate saccades, we found that it carries all the vergence drive that is necessary to shape the activity of the abducens motoneurons to which it projects. Taken together, our results provide evidence that the premotor commands from the brain stem saccadic circuitry, to the target motoneurons, are sufficient to ensure the accurate control shifts of gaze in three dimensions.

Recasting the Smooth Pursuit Eye Movement System

2004 ◽  
Vol 91 (2) ◽  
pp. 591-603 ◽  
Author(s):  
Richard J. Krauzlis
Keyword(s):  
Eye Movements ◽  
Brain Stem ◽  
Smooth Pursuit ◽  
Visual Motion ◽  
Saccadic Eye Movements ◽  
Extrastriate Cortex ◽  
High Acuity ◽  
Voluntary Eye Movements ◽  
New Perspective ◽  
The Brain

Primates use a combination of smooth pursuit and saccadic eye movements to stabilize the retinal image of selected objects within the high-acuity region near the fovea. Pursuit has traditionally been viewed as a relatively automatic behavior, driven by visual motion signals and mediated by pathways that connect visual areas in the cerebral cortex to motor regions in the cerebellum. However, recent findings indicate that this view needs to be reconsidered. Rather than being controlled primarily by areas in extrastriate cortex specialized for processing visual motion, pursuit involves an extended network of cortical areas, and, of these, the pursuit-related region in the frontal eye fields appears to exert the most direct influence. The traditional pathways through the cerebellum are important, but there are also newly identified routes involving structures previously associated with the control of saccades, including the basal ganglia, the superior colliculus, and nuclei in the brain stem reticular formation. These recent findings suggest that the pursuit system has a functional architecture very similar to that of the saccadic system. This viewpoint provides a new perspective on the processing steps that occur as descending control signals interact with circuits in the brain stem and cerebellum responsible for gating and executing voluntary eye movements. Although the traditional view describes pursuit and saccades as two distinct neural systems, it may be more accurate to consider the two movements as different outcomes from a shared cascade of sensory–motor functions.

scholarly journals Time course of spatiotopic updating across saccades

2019 ◽  
Vol 116 (6) ◽  
pp. 2027-2032 ◽  
Author(s):  
Jasper H. Fabius ◽  
Alessio Fracasso ◽  
Tanja C. W. Nijboer ◽  
Stefan Van der Stigchel
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Eye Movement ◽  
Time Course ◽  
Saccadic Eye Movements ◽  
Oculomotor System ◽  
Stimulus Onset ◽  
Oculomotor Behavior ◽  
Behavioral Studies ◽  
The Brain

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.

scholarly journals Isolated medial longitudinal fasciculus syndrome: Review of imaging, anatomy, pathophysiology and differential diagnosis

2017 ◽  
Vol 31 (1) ◽  
pp. 95-99 ◽  
Author(s):  
Puneet S Kochar ◽  
Yogesh Kumar ◽  
Pranav Sharma ◽  
Vikash Kumar ◽  
Nishant Gupta ◽  
...  
Keyword(s):  
Differential Diagnosis ◽  
Eye Movements ◽  
Brain Stem ◽  
Medial Longitudinal Fasciculus ◽  
Rare Occurrence ◽  
Comprehensive Review ◽  
Fiber Tracts ◽  
Imaging Characteristics ◽  
The Brain

Isolated medial longitudinal fasciculus (MLF) syndrome due to infarction limited only to the midbrain is a rare occurrence. The MLF are a group of fiber tracts located in the paramedian area of the midbrain and pons. They control horizontal eye movements by interconnecting oculomotor and abducens nuclei in the brain stem. Such small infarcts can easily be overlooked by young neuroradiologists and trainees. In this review, we discuss the clinical and imaging characteristics, comprehensive review of the anatomy, pathophysiology, and differential diagnosis.

scholarly journals What the Brain Stem Tells the Frontal Cortex. I. Oculomotor Signals Sent From Superior Colliculus to Frontal Eye Field Via Mediodorsal Thalamus

2004 ◽  
Vol 91 (3) ◽  
pp. 1381-1402 ◽  
Author(s):  
Marc A. Sommer ◽  
Robert H. Wurtz
Keyword(s):  
Superior Colliculus ◽  
Frontal Cortex ◽  
Brain Stem ◽  
Signal Transmission ◽  
Frontal Eye Field ◽  
Visual Responses ◽  
Mediodorsal Thalamus ◽  
Visual Activity ◽  
Eye Field ◽  
The Brain

Neuronal processing in cerebral cortex and signal transmission from cortex to brain stem have been studied extensively, but little is known about the numerous feedback pathways that ascend from brain stem to cortex. In this study, we characterized the signals conveyed through an ascending pathway coursing from the superior colliculus (SC) to the frontal eye field (FEF) via mediodorsal thalamus (MD). Using antidromic and orthodromic stimulation, we identified SC source neurons, MD relay neurons, and FEF recipient neurons of the pathway in Macaca mulatta. The monkeys performed oculomotor tasks, including delayed-saccade tasks, that permitted analysis of signals such as visual activity, delay activity, and presaccadic activity. We found that the SC sends all of these signals into the pathway with no output selectivity, i.e., the signals leaving the SC resembled those found generally within the SC. Visual activity arrived in FEF too late to contribute to short-latency visual responses there, and delay activity was largely filtered out in MD. Presaccadic activity, however, seemed critical because it traveled essentially unchanged from SC to FEF. Signal transmission in the pathway was fast (∼2 ms from SC to FEF) and topographically organized (SC neurons drove MD and FEF neurons having similarly eccentric visual and movement fields). Our analysis of identified neurons in one pathway from brain stem to frontal cortex thus demonstrates that multiple signals are sent from SC to FEF with presaccadic activity being prominent. We hypothesize that a major signal conveyed by the pathway is corollary discharge information about the vector of impending saccades.

scholarly journals Saccadic Eye Movements as a Marker of Mental Disorders

2016 ◽  
pp. S365-S371 ◽  
Author(s):  
F. JAGLA
Keyword(s):  
Eye Movements ◽  
Mental Disorders ◽  
Eye Movement ◽  
Saccadic Eye Movements ◽  
Motor Program ◽  
Biologically Active ◽  
Saccadic Eye Movement ◽  
Analytical Processing ◽  
Short Comment ◽  
The Brain

It is accepted that the formulation of the motor program in the brain is not only the perceptual and motor function but also the cognitive one. Therefore it is not surprising that the execution of saccadic eye movements can by substantially affected be the on-going mental activity of a given person. Not only the distribution of attention, but also the focusing the attention may influence the main gain of saccades, their accuracy. Patients suffering from mental disorders have strongly engaged their attention focused at their mental processes. The nature of their problems may be linked to perceptual and/or analytical processing. Such so-called mental set may significantly affect their oculomotor activity in the course of their saccadic eye movement examinations. This short comment points out not only to the influence of the contextually guided and generated saccadic eye movements upon their accuracy but also to the distribution and focusing the attention. The effect of the functional brain asymmetry upon the visually generated saccades and the possible effect of biologically active substances upon the voluntary generated saccades are briefly mentioned. All these influences should be taken into account when planning the saccadic eye movement task. It may be concluded that the repetition of the same oculomotor task in a given person has to be introduced. This may help to follow the effect of complex therapy namely.

Suppression of Task-Related Saccades by Electrical Stimulation in the Primate's Frontal Eye Field

1997 ◽  
Vol 77 (5) ◽  
pp. 2252-2267 ◽  
Author(s):  
Douglas D. Burman ◽  
Charles J. Bruce
Keyword(s):  
Electrical Stimulation ◽  
Eye Movements ◽  
Frontal Lobe ◽  
Premotor Cortex ◽  
Saccadic Eye Movements ◽  
Association Cortex ◽  
Frontal Eye Field ◽  
Visually Guided ◽  
Low Intensity ◽  
Eye Field

Burman, Douglas D. and Charles J. Bruce. Suppression of task-related saccades by electrical stimulation in the primate's frontal eye field. J. Neurophysiol. 77: 2252–2267, 1997. Patients with frontal lobe damage have difficulty suppressing reflexive saccades to salient visual stimuli, indicating that frontal lobe neocortex helps to suppress saccades as well as to produce them. In the present study, a role for the frontal eye field (FEF) in suppressing saccades was demonstrated in macaque monkeys by application of intracortical microstimulation during the performance of a visually guided saccade task, a memory prosaccade task, and a memory antisaccade task. A train of low-intensity (20–50 μA) electrical pulses was applied simultaneously with the disappearance of a central fixation target, which was always the cue to initiate a saccade. Trials with and without stimulation were compared, and significantly longer saccade latencies on stimulation trials were considered evidence of suppression. Low-intensity stimulation suppressed task-related saccades at 30 of 77 sites tested. In many cases saccades were suppressed throughout the microstimulation period (usually 450 ms) and then executed shortly after the train ended. Memory-guided saccades were most dramatically suppressed and were often rendered hypometric, whereas visually guided saccades were less severely suppressed by stimulation. At 18 FEF sites, the suppression of saccades was the only observable effect of electrical stimulation. Contraversive saccades were usually more strongly suppressed than ipsiversive ones, and cells recorded at such purely suppressive sites commonly had either foveal receptive fields or postsaccadic responses. At 12 other FEF sites at which saccadic eye movements were elicited at low thresholds, task-related saccades whose vectors differed from that of the electrically elicited saccade were suppressed by electrical stimulation. Such suppression at saccade sites was observed even with currents below the threshold for eliciting saccades. Pure suppression sites tended to be located near or in the fundus, deeper in the anterior bank of the arcuate than elicited saccade sites. Stimulation in the prefrontal association cortex anterior to FEF did not suppress saccades, nor did stimulation in premotor cortex posterior to FEF. These findings indicate that the primate FEF can help orchestrate saccadic eye movements by suppressing inappropriate saccade vectors as well as by selecting, specifying, and triggering appropriate saccades. We hypothesize that saccades could be suppressed both through local FEF interactions and through FEF projections to subcortical regions involved in maintaining fixation.

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