SEARCH · Search PubMed

Results for “Eye Movements”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources

PubMed1996

Abnormalities of torsional fast phase eye movements in unilateral rostral midbrain disease.

In a patient with a unilateral rostral midbrain lesion, three-dimensional scleral search coil eye movement recordings demonstrated slowing of ipsidirectional torsional fast phase eye movements without any abnormalities of torsional slow phases. On high-resolution MRI, the brainstem lesion localized to the area of the efferent pathways from the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF). This supports the experimental finding that unilateral inactivation of the riMLF results in a loss of ipsidirectional torsional fast phase eye movements and the hypothesis that there is lateralization of function throughout the torsional fast eye movement generating system.

Adult↗

PubMed1995

A 'tachometer' feedback model of smooth pursuit eye movements.

A new model of smooth pursuit eye movements is presented. We begin by formally analyzing the stability of the proportional-derivative (PD) model of smooth pursuit eye movements using Pontryagin's theory. The PD model is the linearized version of the nonlinear Krauzlis-Lisberger (KL) model. We show that the PD model fails to account for the experimentally observed dependence of the eye velocity damping ratio and the oscillation period on the total delay in the feedback loop. To explain the data, a new 'tachometer' feedback model, based on an efference copy signal of eye acceleration, is proposed and analyzed by computer simulation. The model predicts some salient features of monkey pursuit data and suggests a functional role for the extraretinal input to the medial superior temporal area (MST).

Animals↗

PubMed1989

[The physiologic and anatomic principles of rapid eye movements (saccades) and their clinical significance].

Our understanding of the organisation of eye movements has been greatly expanded in recent years, mainly due to studies in animals. A review of the clinically important neurophysiological and anatomical aspects of the generation of rapid eye movements (saccades) will be presented. A knowledge of these basic aspects will assist the clinician's investigation and understanding of pathological eye movements in patients.

Brain↗

PubMed2002

Further evidence that a shared efferent collicular pathway drives separate circuits for smooth eye movements and saccades.

The aim of the present study was to find out whether smooth eye movements (SEMs) evoked by superior colliculus (SC) stimulation are, as suggested by Breznen et al. (1996), artefactual eye movements resulting from a non-physiological response of the saccadic generator. This question was reinvestigated in head-restrained cats. Long-lasting SC stimulation was found to evoke, in a comparable proportion, either a single saccade followed by an uninterrupted SEM or a staircase of two or three saccades interleaved with SEMs. These two different patterns of eye movements could be elicited at a near-threshold current and at low stimulation frequencies. In most cases, SEM direction clearly differed from that of the preceding saccade. This difference between SEM and saccade directions varied in a systematic way as a function of the initial saccade direction. As demonstrated by computer simulation, this observation can be explained if the neural circuit controlling SEMs reaches a saturation level earlier than the saccadic burst-generator. Our results in cats were reminiscent of those reported by Breznen et al. (1996) in the monkey only in some instances, when high frequency stimulation (400-600 Hz) was applied. Indeed, in the case of near-threshold stimulation-elicited staircase saccades, increasing the stimulation frequency led to a progressive disappearance of the smaller subsequent saccades that were substituted by uninterrupted SEM-like movements. Altogether, the present results confirm the view that SEMs are genuine eye movements. These results rule out the hypothesis that SEMs result from a saturation of the saccadic generator and strengthen the hypothesis that SEMs and saccades are distinct movements. We suggest that the same collicular efferent cells carry out the motor command to saccadic and SEM circuits and that the position error originating from the SC may be distributed amongst separate downstream motor systems.

Animals↗

PubMed1983

Vertical and oblique saccadic eye movements.

The peak velocities of saccadic eye movements (saccades) in vertical and horizontal directions were determined in 43 normal subjects using a television system which permits accurate tracing of the corneal image of a small light source. The average peak velocity of a 20 degree horizontal saccade was 420 degrees sec-1 which is in the range of previous reports. The peak velocities of 20 degree saccades were compared between right and left eyes, men and women, and among three age groups and four directions. The rightward saccade was faster than the leftward saccade. Age and sex differences were also found; the peak velocities were less in aged than in adult and they were lower in women than in men. Downward saccade was slower than abduction, adduction and upward saccades. In four normal subjects, oblique saccades were recorded with the same system. The saccades were divided into horizontal and vertical components. The relationship between the peak velocity of the horizontal components and the direction of saccades was studied. The horizontal components had the maximum velocity when the saccade was in the horizontal direction, and the velocity decreased as the obliquity of the direction increased. However, such a peak of the velocity-direction relationship was not pronounced in the vertical components of the saccades, although the velocity of the vertical component showed the maximum in the vertical direction of the saccades. Transient adduction movement was found to be associated with vertical and oblique saccades. This adduction caused the trajectories of the saccades to deviate from linearity. The size of the adduction averaged 1.8 degrees for the 20 degree vertical saccade. Thus the vertical saccade system appears to have an involuntary association with the horizontal eye movement system.

Adolescent↗

PubMed1981

Eye movement as an indicator of brain function.

The level of consciousness between the alert and drowsy states was classified into four stages (Alert, Resting I, Resting II, Drowsy) by studying three factors of the EEG patterns on 23 normal subjects. The eye movements recorded by electro-oculograph were divided into two groups, i.e. rapid eye movements (R type, r type) and slow eye movements (S type, s type). The occurrence of each type of eye movements was confirmed to change in close correspondence to the stages of consciousness. The eye movement on 43 cases with a disturbance of consciousness by metabolic disease were recorded longitudinally according to clinical states. The S type movements were predominantly observed in a state of clouding of consciousness, while the R type and R-S type were observed in a delirious state.

Adult↗

PubMed2005

An anatomically constrained, stochastic model of eye movement control in reading.

This article presents SERIF, a new model of eye movement control in reading that integrates an established stochastic model of saccade latencies (LATER; R. H. S. Carpenter, 1981) with a fundamental anatomical constraint on reading: the vertically split fovea and the initial projection of information in either visual field to the contralateral hemisphere. The novel features of the model are its simulation of saccade latencies as a race between two stochastic rise-to-threshold LATER units and its probabilistic selection of the target for the next saccade. The model generates simulated eye movement behavior that exhibits important characteristics of actual eye movements made during reading; specifically, simulations produce realistic saccade target distributions and replicate a number of critical reading phenomena, including the effects of word frequency on fixation durations, the inverted optimal viewing position effect, the trade-off between first and second fixation durations of refixated words, and the dependence of parafoveal preview benefit on eccentricity.

Eye Movements↗

PubMed1979

Acute effects of alcohol on saccadic eye movements.

Four components of 20 degrees horizontal saccadic eye movements, i.e., latency, mean and maximum velocities, and duration were measured in 16 students under the influence of alcohol and also in a control situation. The experimental procedures were standardized and automated as much as possible. Latency (simple eye reaction time) was not influenced by alcohol in blood concentrations of 0.056--0.116%. Mean and maximum eye velocities decreased by about 9% and duration of saccades increased by 11%. The maximum changes occurred 90--120 min after the start of alcohol ingestion. The changes in velocities and durations correlated more closely with feelings of intoxication than with blood alcohol concentrations. There were great intra- and intersubject variations in reactions to alcohol. The close resemblance between the effects of certain psychotropic drugs, alcohol, fatigue, and decreased attention on eye movement control suggest that all these may act upon the same nervous structures in the brain stem.

Alcoholic Intoxication↗

PubMed2006

Cerebrocerebellar circuits for the perceptual cancellation of eye-movement-induced retinal image motion.

Despite smooth pursuit eye movements, we are unaware of resultant retinal image motion. This example of perceptual invariance is achieved by comparing retinal image slip with an internal reference signal predicting the sensory consequences of the eye movement. This prediction can be manipulated experimentally, allowing one to vary the amount of self-induced image motion for which the reference signal compensates and, accordingly, the resulting percept of motion. Here we were able to map regions in CRUS I within the lateral cerebellar hemispheres that exhibited a significant correlation between functional magnetic resonance imaging signal amplitudes and the amount of motion predicted by the reference signal. The fact that these cerebellar regions were found to be functionally coupled with the left parieto-insular cortex and the supplementary eye fields points to these cortical areas as the sites of interaction between predicted and experienced sensory events, ultimately giving rise to the perception of a stable world despite self-induced retinal motion.

Brain Mapping↗

PubMed2004

Effects of unilateral distractors: a comparison of eye movement and key press responses.

We compared the effects of a unilateral distractor on the latencies of voluntary eye movements and key press responses in order to elucidate some of the differences between these two types of response with respect to processing distractors. On each trial, participants indicated the colour of a central patch by making a left or a right response. The colour of the distractor either matched the target colour or matched the colour associated with the incorrect response. Similarly, the side of the distractor corresponded to the side of either the correct or the incorrect response. The results showed that side congruency exerted a main effect only on eye movement responses, but colour congruency affected eye movement and key press responses similarly. Moreover, when we made the target more distinct from the distractor, only distractors that appeared on the same side as the response elicited a colour congruency effect, for both response modalities. We propose that (1) the appearance of the distractor activates oculomotor cells, which facilitate a subsequent eye movement with the same direction vector, (2) the distinctiveness of the target determines whether colour and side congruency interact, and (3) spatial codes mediate the interaction between colour and side congruency that occurs when the target is sufficiently distinct from the distractor.

Adolescent↗

PubMed1995

Multi-centre comparison of five eye movement detection algorithms.

Although various investigators have suggested algorithms for the automatic detection of eye movements during sleep, objective comparisons of the proposed methods have previously been difficult due to different recording arrangements of different investigators. In this study the results of five eye movement detection algorithms applied to the same data were compared to visually scored data. The percentages of true and false detections are given for various threshold levels in rapid and slow eye movement detections. The methods gave best results when they were used with the same electrode montage they were designed for but the performance decreased when other montages were used. Subtracting the cross-talk of EEG delta activity improved the correctness of eye movement detections.

Journal Article↗

PubMed2004

Torsional eye movements during psychophysical testing with rotating patterns.

Torsional eye movements were measured while subjects viewed a large, high contrast windmill pattern rotating at 53 degrees /s or a small (5 degrees diameter) dot pattern rotating at 115 degrees /s. Both stimuli generated rotational eye movements consisting of torsional optokinetic nystagmus (tOKN) superimposed on a slow torsional drift in the direction of pattern rotation. With the wide-field windmill stimulus, torsional drifts of up to 7 degrees over 20 s were found. The dot pattern produced drifts of up to 2 degrees over 5-20 s. In both cases, the slow-phase speeds during tOKN were low (0.5-1 degrees /s). We conclude that reductions in slip speed are minimal with rotating stimuli, so torsional eye speeds will have a minimal effect on investigations of rotational motion aftereffect strength and perceived speed. While the slow-phase tOKN gain is low, the slow drift in torsional eye position will have significant effects on psychophysical results when the tests rely on keeping selected regions of the stimulus confined to specific areas of the retina, as is the case for phantom or remote motion aftereffects.

Eye Movements↗

PubMed2005

Vestibulo-tactile interactions regarding motion perception and eye movements in yaw.

This paper shows that tactile stimulation can override vestibular information regarding spinning sensations and eye movements. However, we conclude that the current data do not support the hypothesis that tactile stimulation controls eye movements directly. To this end, twenty-four subjects were passively disoriented by an abrupt stop after an increase in yaw velocity, about an Earth vertical axis, up to 120 degrees /s. Immediately thereafter, they had to actively maintain a stationary position despite a disturbance signal. Subjects wore a tactile display vest with 48 miniature vibrators, applied in different combinations with visual and vestibular stimuli. Their performance was quantified by RMS body velocity during self-control. Fast eye movement phases were analyzed by counting samples exceeding a velocity limit, slow phases by a novel method applying a first order model. Without tactile and visual information, subjects returned to a previous level of angular motion. Tactile stimulation decreased RMS self velocity considerably, though less than vision. No differences were observed between conditions in which the vest was active during the recovery phase only or during the disorienting phase as well. All effects of tactile stimulation found on the eye movement parameters could be explained by the vestibular stimulus.

Adult↗

PubMed1989

[Eye movement is controlled by basal ganglia-induced GABAergic inhibition].

Saccadic eye movement is controlled by a midbrain structure, superior colliculus (SC). Cells in its intermediate layer show a burst of spikes before saccades to the contralateral disc. A major input to the SC comes from the substantia nigra pars reticulata (SNr). SNr cells are characterized by their high frequency tonic discharge. Many of them stop discharging before a contralateral saccade only when the saccade is made intentionally. The mirror image-like relationship between the SNr and the SC suggests that the nigro-collicular connection is inhibitory. To determine whether the nigro-collicular inhibition is necessary for normal eye movements, we injected a small amount of GABA-related substances into the SC or the SNr. Following injection of muscimol (GABA agonist) into the SC, contralateral saccades became delayed, hypometric and slower; the monkey finally became unable to make saccades. This result indicated that the SC is crucial for normal saccades and that SC cells have ample GABA receptors. Following injection of bicuculline (GABA antagonist), irrepressible saccades occurred repeatedly to the contralateral side, suggesting that SC cells are under tonic inhibition which is mediated by GABA. Similar involuntary saccades were induced by injection of muscimol into the SNr. This suggested that the SNr is the origin of the GABAergic tonic inhibition. These results suggested that the basal ganglia control the initiation of saccadic eye movement by changing the level of the nigro-collicular inhibition.

Animals↗

PubMed1997

Neuronal activity in the frontal eye field of the monkey is modulated while attention is focused on to a stimulus in the peripheral visual field, irrespective of eye movement.

We tested the hypothesis that the frontal eye field (FEF) is involved in attention to the peripheral visual field (PVF). Neuronal activity was recorded in the FEF of two monkeys while they were performing three oculomotor tasks. In the visual attention task (VAT), the monkeys released a lever when a test stimulus (TS) presented in the PVF dimmed while they were looking at a central fixation point (FP). In the visual saccade task (VST), the monkeys exhibited saccadic eye movements when the FP was extinguished. In the visual fixation task (VFT), the monkeys released the lever when the FP dimmed. Overall, the activities of 80 FEF neurons were examined. The responses to visual stimuli of 41 of these neurons (51%) were modulated during the VAT. Twenty-five neurons showed pre-saccadic activity. Of these, 13 neurons (52%) exhibited activity modulation during the VAT. Eighteen neurons showed no pre-saccadic activity. Of these, 10 neurons (56%) exhibited activity modulation during the VAT. These results suggest that the FEF is involved in selecting the visual stimuli relevant to performing a task irrespective of eye movements.

Animals↗

PubMed2003

Improvement of exploratory eye movements in schizophrenic patients during recovery period.

In the present paper exploratory eye movements were examined as biologic markers in both acute schizophrenic patients (acute patients discharged after approximately 3 months and treated as outpatients, n = 8; acute patients who were still in hospital after 6 months, n = 8) and chronic schizophrenic patients (hospital stay >5 years, n = 15) in comparison with age-matched healthy subjects (n = 30). Using an eye-mark recorder, exploratory eye movements were analyzed for mean gazing time (MGT), and total eye scanning length (TESL) as subjects viewed six simple pictures in preparation for copying them. In acute schizophrenic patients discharged after 6 months (DP), MGT became significantly shorter and TESL became longer after 3 or 6 months treatment. In acute schizophrenic patients during admission after 6 months, TESL became longer after 3 or 6 months of treatment. However, no significant changes were observed in chronic patients in these measures. In schizophrenic patients, negative symptom scores were positively correlated with MGT (r = 0.43; P < 0.001), and negatively correlated with TESL (r = -45; P < 0.001). These findings suggest that exploratory eye movements are a biologic state and trait marker useful for evaluation of schizophrenia.

Acute Disease↗

PubMed1995

Effects of superior temporal polysensory area lesions on eye movements in the macaque monkey.

1. On the basis of its anatomic connections and single-unit properties, the superior temporal polysensory area (STP) would seem to be primarily involved in visuospatial functions. We have examined the effects of lesions of STP on saccadic eye movements, visual fixation, and smooth pursuit eye movements to directly test the hypothesis that STP is involved in visuospatial and visuomotor behavior. 2. Seven monkeys were trained to make saccades to targets 8, 15, and 22 degrees from a central fixation point along the horizontal meridian and 8 degrees from the central fixation point along the vertical meridian. One monkey was also trained to make saccades to auditory targets. The same monkeys were trained to foveate a stationary central fixation point and to follow it with a smooth pursuit eye movement when it began moving 5, 13, or 20 degrees/s. Four monkeys received unilateral STP lesions, one received a bilateral STP lesion, and as a control, two received unilateral inferior temporal cortex (IT) lesions. After testing, three of the animals with unilateral STP lesions received an additional STP lesion in the hemisphere contralateral to the first lesion. Similarly, one animal with a unilateral IT lesion received an additional IT lesion in the hemisphere contralateral to the first lesion. 3. All monkeys with complete removal of STP showed a significant increase in saccade latency to the most peripheral contralateral target, and most also had increased saccade latencies to the other contralateral targets. Saccades directed to targets along the vertical meridian or toward targets in the hemifield ipsilateral to the lesion were not impaired by removal of STP. By contrast, IT lesions did not impair the monkeys' ability to make saccadic eye movements to visual stimuli at any location, showing that saccades to visually guided targets are not impaired nonspecifically by damage to visual cortex. 4. The deficit in making eye movements after STP lesions was specific to saccade latency, with little effect on the accuracy of saccades to visual targets. 5. In the one monkey trained to make saccades to auditory targets, removal of STP did not impair saccades to auditory targets contralateral to its lesion, despite this monkey showing the largest increase in saccades latencies to visual targets. 6. There was complete recovery of saccade latency to the baseline level of performance on the saccade task after all STP lesions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2003

Horizontal rhythmical eye movements consistently diminish the arousal provoked by auditory stimuli.

OBJECTIVES: Theoretical models implicating the orienting reflex as an explanatory mechanism in the eye-movement desensitization and reprocessing (EMDR) treatment protocol are contrasted and tested empirically. We also test whether EMDR effects are due to a distraction effect. DESIGN: A repeated measure design is used in two experiments. The first experiment employed two independent variables, eye condition (moving vs. stationary) and tone (a pseudo-randomized series of low and high intensity tones). In Expt 2, eye condition was replaced by attentional demand conditions (low or high). In both cases, electrodermal responses served as the dependent variable. METHOD: Participants were recruited from the Psychology Department at Cardiff University. In Expt 1, participants were required to either pursue a moving stimulus following auditory challenge or engage in an eyes-stationary task. In Expt 2, the task following auditory challenge required participants to identify specific items from letter strings in low and high attentional demand conditions. RESULTS: Lower levels of electrodermal arousal were identified in tasks eliciting eye movements, compared to no eye movements. This effect was not due to the attentional requirements of the task. CONCLUSIONS: Eye movements following auditory challenge result in an effect of psychophysiological de-arousal. This supports the reassurance reflex model of EMDR proposed by MacCulloch and Feldman (1996).

Acoustic Stimulation↗