Search PubMed⌕ Search

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.

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

At least 649 records · Page 36Linked to original sources
PubMed1983

The impact of automatic digit naming ability on a clinical test of eye movement functioning.

One of the primary reasons for the clinical measurement of eye movements in children is probing the relationship of oculomotor functioning with reading. The purpose of this study was to investigate the relationship between a subjective clinical test of lateral eye movements (KD Saccade Test) using a visual-verbal response format with the ability to name numbers automatically in the absence of eye movements in a first and second grade population. The results support the hypothesis that the eye movement skills measured with subjective visual-verbal formats as described in this study are deficits in automaticity of number knowledge ability and not oculomotor dysfunctions in some children.

Child↗
PubMed1993

Lesions of the frontal eye field impair pursuit eye movements, but preserve the predictions driving them.

Visually guided eye movements are driven by a mix of current signals (e.g. visual motion) and prior experience (predictive strategies). Previously, large ablations of the frontal eye field (FEF) impaired visually guided smooth pursuit. This study examined if the pursuit decrement could be laid to a selective loss in predictive signals. Normal monkeys demonstrated some of the same predictive eye movements documented in humans. They pursued periodic visual targets with near-zero phase lag. When such targets suddenly disappeared, the monkeys continued smooth pursuit without visual guidance for several reaction times. These epochs of 'blind pursuit' achieved a peak velocity proportional to the prior target frequency just experienced by the monkey. With predictable step-ramp targets smooth eye movements sometimes preceded target motion (anticipatory pursuit). Reaction time to begin pursuit was influenced by the target velocity of prior trials. Small unilateral ablations of 'low threshold' FEF showed smooth pursuit if the fundus of the arcuate sulcus was thoroughly removed. On the step-ramp targets the slowing was evident in both the initial 100 ms and subsequent portions of pursuit. During sine pursuit blind epochs were more slowed by surgery than were visually guided epochs of pursuit. Ipsilateral anticipatory pursuit was abolished in one subject, but not in the other subject with pursuit deficits. Otherwise, pursuit after surgery continued to display the influence of predictive strategies. The average phase lag of periodic pursuit remained much less than the pursuit system's reaction time. Blind epochs persisted after the periodic target disappeared, albeit with a lower peak velocity. Reaction time to begin pursuit of step-ramp targets remained a function of the monkey's experience on prior trials. It is argued that the FEF pursuit deficits do not reflect the loss of visual motion signals or the loss of some 'cognitive' signal such as a prediction about the target's motion, but rather can be explained as a motor deficit.

Animals↗
PubMed1990

Association of tardive dyskinesia with increased frequency of eye movement disturbances in chronic schizophrenic patients. A clinical note.

The study of eye movement dysfunction in chronic schizophrenics by electronystagmography revealed a significant increase of saccadic dysmetria as well as saccadic intrusions in smooth pursuit in schizophrenic patients with tardive dyskinesia (TD) compared with those without TD and with healthy controls. The pattern of eye movement dysfunction in schizophrenia allows clear discrimination from patients with similar movement disorders due to Huntington's disease. Of several possible explanation's of the schizophrenic eye movement dysfunction the authors favour the hypothesis of a common pathogenetic link between TD and eye movement disorders in schizophrenia, consisting in an underlying dysfunction of regions involved in the regulation of involuntary attention such as the parietal cortex and striatolimbic structures of the right hemisphere. Recent literature supports the assumption of right hemispheric dysfunction in schizophrenia.

Adult↗
PubMed2000

Three dimensional eye movement analysis during off vertical axis rotation in human subjects.

Three dimensional analysis of eye movements during OVAR was performed in 37 healthy human subjects using the computerized image recognition technique developed by us. The modulation component of eye movement was observed in all three components (horizontal, vertical and torsional), whereas the bias component was only clearly seen in the horizontal eye movement. The phase lag of the torsional component was quite consistent with a small variation between each subject with respect to the head position. The phase of vertical eye movement was, however, less consistent compared to that of the horizontal and torsional eye movements. From these results, in human subjects, there should be some differences in the dynamic function of the otolith system compared to that observed in monkeys.

Adult↗
PubMed2003

Visual motion illusions, eye movements, and the search for objectivity.

The initial interpretations of motion phenomena are often in terms of eye movements. It reflects a desire to link an objective expression of motion (of the eyes) with a subjective experience of motion. This approach is examined historically with respect to induced motion, motion aftereffects, visual vertigo, autokinetic effects and stroboscopic motion. All but one of these phenomena were initially observed in the natural environment and they have subsequently been studied under laboratory conditions. Eye movements are not correlated with induced motion, the motion aftereffect, or stroboscopic motion, but they do correspond to the direction and extent of visual vertigo. The extent of apparent visual motion in the autokinetic effect far exceeds that of involuntary eye movements but there might be a weak relation between them. If eye movements are to provide a reasonable account of motion illusions then they should apply to all the contours that are visible. This does apply to visual vertigo, but not to induced motion, the motion aftereffect and stroboscopic motion, all of which involve relative motion in a visible display. The autokinetic phenomenon involves the perception of isolated stimuli, and so interpretations in terms of some internal eye movement signals remain sustainable.

Eye Movements↗
PubMed1995

The characteristics of eye movements made during visual search with multi-element stimuli.

Saccadic eye movements during visual search made to detect a target embedded in a set of randomly distributed, identical elements have been measured. Both the time T1/2 taken to press a button to denote target detection (the manual response time) and the time Tf taken to fixate the target were determined. It is established that these two response times are closely related to each other, and have similar dependence on the number of reference elements N, both in search tasks for which T1/2 is independent of N (parallel search) and in those for which T1/2 is proportional to N (serial search). The properties of the eye movements made by two subjects in response to a variety of stimuli have been subjected to detailed analysis. It is shown that the number of fixations made during a given search is proportional to the manual response time T1/2 and that the probability of locating the target with a single fixation falls steeply as T1/2 increases. The latency of the first saccade is approximately linearly dependent on T1/2, and latencies made in performing a given task are distributed in a Gaussian manner the spread of the latency values increasing as the mean latency increases. It is conclude that the measurement of eye movements provides a more detailed description of visual search than that given by measurement of manual response times, and that in terms of eye movements, only a subset of those tasks for which T1/2 is independent of N can be classified as parallel.

Adult↗
PubMed1993

[Algorithm for calibrating eye movements].

A mathematical model and the corresponding computer program based on an algorithm for calibration of eye movements are described. The latter is used to represent and analyse eye movements on a monitor screen using the EYE/HAND software, with the aid of which movements of eye and hand can be represented either simultaneously or separately. Demands on the rate of data acquisition and representation of the curves (real-time monitoring) are satisfied. Calibration is based on vector transformation of the digitised analog values to monitor coordinates. The parameters of the transformation algorithm are determined by fixation of the eye movements to freely selectable monitor screen markers.

Calibration↗
PubMed1987

Slow eye movements induced by apparent target motion in monkey.

Slow eye movements were observed while the monkey fixated on a subject-stationary, small target light in front of a moving optokinetic drum in an attempt to suppress optokinetic nystagmus (OKN). These slow eye movements of low amplitude were directed opposite to the moving optokinetic stimulus and, hence, were not identical to slow phases of incompletely suppressed OKN. It is assumed, based on comparable findings in humans, that these slow eye movements are induced by a perceived target motion, i.e. by the perception of an apparent motion of the subject-stationary fixation light opposite to the actual motion of the optokinetic drum.

Animals↗
PubMed1995

Developmental trends in pursuit eye movements among preschool children.

The purpose of this study was to investigate the developmental differences in pursuit eye movements among preschool children. The subjects were 28 children aged 3 to 6 years old and 5 adults aged 22 to 37 years. The target was moved sinusoidally on the horizontal plane at 0.3-, 0.5-, and 0.7-Hz stimulus frequency. The power ratio which represented the smoothness of eye movements and the phase difference between eye movements and target movement was calculated. The power ratio decreased with increased stimulus frequency for all subjects, indicating that eye movements became less smooth. At all stimulus frequencies, the power ratio was higher for adults than for children. Among the three age groups of children, there was no statistically significant difference on this parameter. The phase shifted from a small amount of lead for no lag to the lag with faster stimulus frequency in adults, but the gap was not statistically significant. For children, there was a statistically significant difference across age groups on change in the phase difference. These findings may suggest that the developmental differences in pursuit eye movements of children across ages 3 to 6 years were clear in what related to the phase difference.

Adult↗
PubMed1987

Involvement of Purkinje cells in evoking saccadic eye movements by microstimulation of the posterior cerebellar vermis of monkeys.

Neural mechanisms for evoking saccadic eye movements by microstimulation of the posterior vermis were investigated in monkeys trained to fixate a visual target. The low-threshold region from which saccadic eye movements could be evoked with currents less than 10 microA was confined to lobule VII in two monkeys and it included a posterior part of lobule VI (lobule VIc) in another monkey. The region from which saccade-related neural activity was recordable coincided with the low-threshold region. This region corresponded to the vermal lobules from which eye position and saccade-related Purkinje cells were recorded. Kainic acid (kainate) injected in the white matter of lobule VII resulted in severe losses of Purkinje cells within a radius of 1-2 mm of the injection site. The lesion tended to be larger toward the peripheral cerebellar cortices, which were connected to the injection site by natural courses of the afferent and efferent fibers. After the kainate administration, the distribution of saccade-related neural activity did not differ significantly from that of the preoperative mapping, in spite of the severe losses of cortical neurons. Burst discharges of mossy fibers were recordable in the white matter near the injection site, indicating that afferent fibers were relatively unaffected by kainate. After kainate administration, the saccadic eye movements could no longer be evoked by microstimulation applied to the posterior vermis. The stimulus sites from which saccades could be evoked after kainate administration were always associated with the presence of intact Purkinje cells. In such cases, the minimum current necessary to evoke saccades depended on the percentages of intact Purkinje cells spared. In the folia with normal Purkinje cell layers, the amplitude and direction of evoked saccades and the thresholds for evoking such eye movements were almost comparable to the preoperative data. Saccadic eye movements in response to microstimulation of the posterior vermis were caused by orthodromic impulses conveyed through the axons of the Purkinje cells. Insofar as the saccades elicited from lobule VII with currents less than 10 microA are concerned, antidromic activation of the afferent fibers is not the neural mechanisms subserving the oculomotor responses.

Animals↗
PubMed1998

Use of the Taylor Visagraph II system to evaluate eye movements made during reading.

BACKGROUND: The Taylor Visagraph II is a relatively new device designed to evaluate eye movements made during reading. It uses goggles with infrared optics to detect the eye movements and computer software to determine the number of fixations, regressions, and other characteristics of the eye movements. The system also calculates several scores, including a school-grade equivalent for the reader. METHODS: Fifty first-year optometry students served as subjects. Each read five standard Taylor Level 10 (College) paragraphs during each of two sessions while eye movements were assessed by the Visagraph II. RESULTS: The Visagraph II operated correctly for 498 of the 500 trials; operator error caused two malfunctions. Significant differences were found between scores from the first paragraph read and subsequent paragraphs. Nonlinear relationships were found between most of the variables, especially those that involved grade levels and spans of recognition. Also of interest was the wide range of reading eye-movement skills; several of the optometry students appeared to have skills that placed them at below fourth grade level. CONCLUSIONS: The Visagraph II performed properly over a large number of trials and produced data that seemed to be reliable indicators of reading skills. Paragraph-to-paragraph variations in mean scores suggest caution in interpretation of small changes in performance across paragraphs and the need for at least one practice trial before usable data are obtained.

Adult↗
PubMed2002

Rapid Eye Movement Sleep-related Parasomnias.

Among the rapid eye movement (REM) sleep-related parasomnias, the most common and important disorder for which patients present is REM sleep behavior disorder (RBD). Rapid eye movement sleep behavior disorder is often undiagnosed for many years, despite the sometimes bizarre and harmful behaviors involved. Complete evaluation and accurate diagnosis are essential for proper management. This includes medical, sleep/wake, psychiatric, and neurologic histories. Although they may raise feelings of guilt or shame, questions related to sexual and violent behaviors should be directed towards the identified patient as well as their bed partners. Objective studies should include nocturnal polysomnogram with audiovisual monitoring of behavior, electromyography (EMG) of all limbs, and seizure montage. Brain imaging, clinical electroencephalogram (EEG), neuropsychometric testing, and actigraphy may be used adjunctively. Clinicians should have a high index of suspicion for other neurologic conditions, especially neurodegenerative disorders and narcolepsy, because many patients with RBD have these conditions. Rapid eye movement sleep behavior disorder may actually precede symptoms and signs associated with other neurologic disorders, so close follow-up is recommended. Medications that may be causing or exacerbating RBD should be withdrawn, if possible. Clonazepam is very effective in reducing the symptoms of RBD. This treatment is generally well tolerated and may be used long-term. Discontinuation of clonazepam usually leads to relapse of symptoms. Safety-related issues should be discussed with patients and their families.

Journal Article↗
PubMed1973

Influence of eye movements on geniculo-striate excitability in the cat.

1. The excitability of the geniculo-striate pathway during a saccadic eye movement was studied in alert cats with chronically implanted electrodes. Excitability was assessed by the amplitude of post-synaptic components of field responses in both lateral geniculate nucleus and visual cortex to electrical stimulation of the optic chiasm. Modifications in amplitude were evaluated during the period following eye movements, by triggering a stimulator from potential shifts in the electrooculograms and altering delays in the stimulus pulse.2. The post-synaptic component of the geniculate response was markedly depressed for about 150 msec, reaching a trough at approximately 100 msec after the initiation of an eye movement. This effect was dependent on the visual environment and was not observed in complete darkness. A similar depression occurred when the visual field was abruptly moved by retinal impulses generated by a quick displacement of the image of the visual world associated with an eye movement. The depression reflected a reduction of cellular discharge to the orthodromic volley and hence a suppression of the transmission of visual information through the lateral geniculate nucleus. This may be a mechanism for saccadic suppression.3. The post-synaptic components of the cortical response were enhanced for about 200 msec, reaching a peak at approximately 150 msec after the initiation of an eye movement. Although this facilitation occurred also in complete darkness, it did not occur when the visual field was abruptly shifted while the eyes were stationary. The fact that it occurred with eye movements and exclusively in the post-synaptic components suggests that it was caused by signals from a system closely related to eye movements. This may be a manifestation of the corollary mechanism.

Action Potentials↗
PubMed1997

[Study of non-visually induced smooth pursuit eye movements and their predictability using pseudorandom target motion].

It has been found that the smooth pursuit eye movements (SPEM) are elicited by not only visual stimuli but also non-visual information such as the subject's fingertip movement and a moving sound source. We have already reported the quantitative analysis of SPEM which were induced by somatosensory and acoustic information. In the previous study, we used a sinusoidal waveform that could be highly predictable. Since it is wellknown that predictive control has an important role in the normal SPEM, we expect the predictive control to function in non-visually induced SPEM (NVSPEM). We quantitatively analyzed NVSPEM and normal SPEM evoked by pseudorandom target motion in ten human subjects who had no ocular, oculomotor or vestibular disorders. NVSPEM were induced by the following two non-visual targets: 1, subjects' fingertip motion as a somatosensory target ("Somato"), 2, a small loudspeaker (3-cm diameter.) generating white noise with an intensity of about 60 dB (A) as an acoustic target ("Acoustic"). A servo-controlled swing arm of 50cm was used to drive the subject's fingertip and the acoustic target of the small loudspeaker. The horizontal motion of the swing arm was controlled by a personal computer. The pseudorandom target motion was generated by mixing four sinusoids (0.1, 0.2, 0.4, 0.8 Hz) of which the phases were randomly selected and the peak velocities were equally set at 19 deg/s. The mean peak velocity of the target was 26.2 deg/s and the amplitude was limited within 15 deg. Horizontal eye movements were recorded by DC electro-oculography and on an analogue datatape. The experiment was performed for 30 s in complete darkness so that the subjects' fingertip and loudspeaker as such remain invisible to the subject. Signals from the data recorder were smoothed by a low pass analogue filter of 20Hz, after digitization with a sampling frequency of 200 Hz and precision of 12 bits, and stored on a computer. The slow and quick eye movement components, both of which were present in each class of horizontal eye movement investigated, were identified and separated by a computer. Then we developed a method of automatic quantitative analysis of ocular tracking eye movement. Gain and phase values for the smooth pursuit eye movements were obtained in each condition. In the lower frequency area, the gain elicited by the pseudorandom stimulation was lower than the smooth pursuit gain for sinusoidal (predictable) stimulation in all conditions. In the highest frequency, gain values did not differ significantly among the three. For the sinusoidal stimulation, the phase of the smooth component of "Visual" always had a lag and that of "Somato" and "Acoustic" had a lead in lower frequencies. All conditions had a phase shift, decreasing with increasing frequency. For the pseudorandom stimulation the phase of the SPEM had a lead only in the lowest frequency (0.1 Hz). On the other hand, in the NVSPEM the phases of the three lower frequencies had a lead which had a tendency of a larger phase lead with decreasingly frequency. In the highest frequency (0.8 Hz), we could see a short phase lag. These findings support the idea that SPEM and NVSPEM have a mutual or similar physiologic system and overlap part of the anatomical pathway.

Adult↗
PubMed1988

Recording eye movements and vestibular tests utilizing EEG equipment.

Abnormalities of spontaneous eye movements occur frequently in patients with neurological diseases, and abnormalities of eye movements induced by vestibular and optokinetic stimulations have great diagnostic value. Their amplitude, frequency, duration, direction, and rhythmicity can be graphically recorded utilizing EEG equipment, and their speed can be easily calculated. The author emphasizes that eye movements can and should be studied in EEG laboratories, since neurologists are well prepared for the interpretation of the electrooculographic (and electronystagmography) data.

Electroencephalography↗
PubMed2003

Function of otolith organ in goldfish revealed from analysis of eye movement induced by acceleration.

An otolith organ on ground behave as a detector of both gravity and linear acceleration, and play an important role in controlling posture and eye movement for tilt of the head or translational motion. On the other hand, a gravitational acceleration ingredient to an otolith organ disappears in microgravity environment. However, linear acceleration can be received by otolith organ and produce a sensation that is different from that on Earth. It is suggested that in microgravity signal from the otolith organ may cause abnormality of posture control and eye movement. Therefore, the central nervous system may re-interprets all output from the otolith organ to indicate linear motion. A study of eye movement has been done a lot as one of a reflection related to an otolith organ system. In this study, we examined function of otolith organ in goldfish revealed from analysis of eye movement induced by linear acceleration or the tilt of body. We analyzed both torsional and vertical eye movements from video images frame by frame. For tilting stimulation, torsional eye movements induced by head down was larger than that induced by head up for larger tilt angle than 30 degrees. In the case of linear acceleration below 0.4 G, however, no clear differences were observed in both torsional and vertical eye movement. These results suggest that body tilt and linear acceleration may not be with equivalent stimulation to cause eye movement on the ground.

Acceleration↗
PubMed1999

Smooth-pursuit eye-movement deficits with chemical lesions in macaque nucleus reticularis tegmenti pontis.

Anatomic and neuronal recordings suggest that the nucleus reticularis tegmenti pontis (NRTP) of macaques may be a major pontine component of a cortico-ponto-cerebellar pathway that subserves the control of smooth-pursuit eye movements. The existence of such a pathway was implicated by the lack of permanent pursuit impairment after bilateral lesions in the dorsolateral pontine nucleus. To provide more direct evidence that NRTP is involved with regulating smooth-pursuit eye movements, chemical lesions were made in macaque NRTP by injecting either lidocaine or ibotenic acid. Injection sites first were identified by the recording of smooth-pursuit-related modulations in neuronal activity. The resulting lesions caused significant deficits in both the maintenance and the initiation of smooth-pursuit eye movements. After lesion formation, the gain of constant-velocity, maintained smooth-pursuit eye movements decreased, on the average, by 44%. Recovery of the ability to maintain smooth-pursuit eye movements occurred over approximately 3 days when maintained pursuit gains attained normal values. The step-ramp, "Rashbass" task was used to investigate the effects of the lesions on the initiation of smooth-pursuit eye movements. Eye accelerations averaged over the initial 80 ms of pursuit initiation were determined and found to be decremented, on the average, by 48% after the administration of ibotenic acid. Impairments in the initiation and maintenance of smooth-pursuit eye movements were directional in nature. Upward pursuit seemed to be the most vulnerable and was impaired in all cases independent of lesioning agent and type of pursuit investigated. Downward smooth pursuit seemed more resistant to the effects of chemical lesions in NRTP. Impairments in horizontal tracking were observed with examples of deficits in ipsilaterally and contralaterally directed pursuit. The results provide behavioral support for the physiologically and anatomic-based conclusion that NRTP is a component of a cortico-ponto-cerebellar circuit that presumably involves the pursuit area of the frontal eye field (FEF) and projects to ocular motor-related areas of the cerebellum. This FEF-NRTP-cerebellum path would parallel a middle and medial superior temporal cerebral cortical area-dorsolateral pontine nucleus-cerebellum pathway also known to be involved with regulating smooth-pursuit eye movements.

Animals↗
PubMed1992

Eye movements during motion after-effect.

Using the magnetic search coil technique, we measured torsional eye movements in four male subjects during and after rotation of a visual display around the line of sight. During rotation of the display, subjects developed a torsional nystagmus with slow-phases in the direction of target rotation that had a typical gain of less than 0.01. Upon cessation of display motion, subjects experienced a motion after-effect (MAE) in the direction opposite prior target rotation, which persisted for greater than 15 sec. During this MAE, slow-phase eye movements of low velocity were in the same direction as the MAE, but did not persist as long as perceptual effects. In separate experiments, horizontal eye movements were recorded during horizontal stimulus motion; during MAE, no eye movements occurred due to stronger fixation mechanisms. We conclude that MAE is not caused by retinal slip of images, but MAE and the accompanying eye movements might be produced by shared or similar mechanisms.

Adult↗