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PubMed1989

Computer analysis of smooth pursuit eye movements.

Smooth-pursuit eye movements are analyzed using a system analysis approach. Frequency domain methods are used to factor the smooth-pursuit response into a linear component and a nonlinear or remnant component. The linear component is that part of the tracking response that is linearly related to the target movement; the remnant is the component remaining after the linear component is subtracted out. Tracking abnormalities that are not evident by inspection of the complete eye-movement record become obvious upon inspection of the remnant.

Computers↗
PubMed1968

Operant control of eye movements during human vigilance.

Eye movements were used as a criterion of observing responses in a vigilance task. Time on watch and signal rates similarly affected both eye-movement rates and percentage of detections. Observing rate may account for detection data, and may be a more stable measure of vigilance than detection rate is, especially when very few signals occur.

Analysis of Variance↗
PubMedDate not supplied

Imaging of eye movement with fast MRI.

PURPOSE: Imaging of eye movement disorders has so far been restricted to the semifunctional cine mode of CT and MRI. Since real-time imaging of eye movement is necessary to investigate dynamic disorders, the aim of our study was to implement a fast MR technique to investigate eye movement in a real-time mode. METHOD: Six healthy volunteers and three patients suffering from end-point nystagmus were examined with fast MR sequences while performing the following eye movements: holding different gaze positions, reading a defined text to demonstrate saccadic movements, and holding a primary gaze position and maximal end-point position to cause nystagmus when present. RESULTS: In all cases, we were able to delineate eye movement with fast MRI. Anatomic and functional information could be obtained simultaneously for the first time through observation of saccadic and pursuit eye movements. CONCLUSION: Fast MRI allows for the assessment of dynamic eye movement without the restrictions of cine mode and is able to provide the clinician with additional information in the evaluation of functional movement disorders.

Adult↗
PubMed2002

Brain activation during smooth-pursuit eye movements.

A potential application of studying eye movements with functional MRI (fMRI) is to examine patient populations with known eye movement dysfunction, but the reliability with which normal subjects demonstrate activity in specific brain regions has not been established. To date, fMRI studies of smooth-pursuit eye movements have used relatively small numbers of subjects and have been restricted to fixed-effects analyses. We extend these studies to whole brain imaging at 1.5 T, properly accounting for intersubject variation using random effects analysis. Smooth-pursuit eye movements elicited activation consistently in dorsal cortical eye fields and cerebellum. Subcortical activation was greatly attenuated, but not eliminated, with the random-effects second-level analysis. In addition, session-dependent changes in activation were greater in some regions than others and may indicate areas of brain, such as the supplementary eye fields, that are sensitive to attentional modulation of eye movements.

Adult↗
PubMed1995

The role of visual attention in saccadic eye movements.

The relationship between saccadic eye movements and covert orienting or visual spatial attention was investigated in two experiments. In the first experiment, subjects were required to make a saccade to a specified location while also detecting a visual target presented just prior to the eye movement. Detection accuracy was highest when the location of the target coincided with the location of the saccade, suggesting that subjects use spatial attention in the programming and/or execution of saccadic eye movements. In the second experiment, subjects were explicitly directed to attend to a particular location and to make a saccade to the same location or to a different one. Superior target detection occurred at the saccade location regardless of attention instructions. This finding shows that subjects cannot move their eyes to one location and attend to a different one. The result of these experiments suggest that visuospatial attention is an important mechanism in generating voluntary saccadic eye movements.

Attention↗
PubMed2002

The latency of saccades, vergence, and combined eye movements in children and in adults.

PURPOSE: To examine the latency of eye movements in three-dimensional space (saccade, vergence, and combined saccade-vergence) in children and adults. METHODS: Fifteen normal children (4.5-12 years of age) and 15 normal adults (22-44 years of age) were tested. A standard paradigm was used to elicit pure lateral saccades at far and close viewing distance, pure vergence (convergence and divergence), and saccade combined with vergence movements. Horizontal eye movements from both eyes were recorded simultaneously by the oculometer, a photoelectric device. RESULTS: The mean latency in saccades, vergence, and combined eye movements was longer in children than in adults; the variability of such latency values was also larger in children. There was a progressive decrease with age in mean latency. All latencies approached or reached adult levels at approximately 10 to 12 years of age. Latency of saccades at close viewing distance was shorter than that at far in both adults and children. Convergence latency was longer than divergence latency in adults and most of the children. Latency of components of combined movements was longer than that of corresponding pure movements. Children initiated combined movements by triggering the vergence component first, whereas adults did not show a dominant pattern. The percentage of synchronous start of the two components was significantly higher in adults. CONCLUSIONS: Saccade- and vergence-triggering mechanisms are distinct and mature progressively and in parallel with age. The capacity for synchronization of the two components of combined eye movements develops more slowly and remains below adult level, even at the age of 12 years.

Adult↗
PubMed1991

Frontal eye field lesions impair predictive and visually-guided pursuit eye movements.

The study initially explored the frontal eye field's (FEF) control of predictive eye movements, i.e., eye movements driven by previous rather than current sensory signals. Five monkeys were trained to pursue horizontal target motion, including sinusoidal targets and "random-walk" targets which sometimes deviated from a sine motion. Some subjects also tracked other target trajectories and optokinetic motion. FEF ablations or cold lesions impaired predictive pursuit, but also degraded visually guided foveal pursuit of all targets. Unilateral lesions impaired pursuit of targets moving in both horizontal orbital fields and in both directions of movement. Saccadic estimates of target motion were generally accurate. The slow-phase velocity of optokinetic pursuit (collected after 54 s of OKN) also appeared normal. Pursuit recovered over 1-3 weeks after surgery but the deficits were then reinstated by removal of FEF in the other hemisphere. Thereafter, a slight deficit persisted for up to 10 weeks of observation in two subjects. The pattern of symptoms suggests that FEF lies subsequent to parietal area MST and prior to the pontine nuclei in controlling pursuit eye movements.

Animals↗
PubMed2003

Detection of eye movements from fMRI data.

Awake humans make eye movements with amplitudes and frequencies that depend on behavioral state and task. This poses two problems for functional magnetic resonance imaging (fMRI) studies that compare brain activity across tasks. First, motion of the eye in the orbit increases the variance of the MR signal in adjacent regions of the orbitofrontal cortex, hampering activation detection. Second, eye movements are associated with activity in a distributed network of brain areas, confounding comparisons of task activation. Direct measurement of eye movements in the scanner bore is possible with expensive and technically demanding equipment. A method is described that detects eye movements directly from MR data without the use of additional equipment. Changes in the MR time series from the vitreous of the eye were observed that correlated with eye movements, as measured directly with an infrared pupil tracking system. In each of 10 subjects, the variance of the MR time series from the eye vitreous was greater when the subject made eye movements than when the subject fixated centrally (average standard deviation (SD) 99.7 vs. 75.6, P = 0.001). The assessment of eye movements directly from fMRI data may be especially useful for retrospective and meta-analyses.

Adult↗
PubMed1985

The spontaneous eye movements in the awake kitten.

The spontaneous eye movements were analysed comparatively in the kitten and in the cat. The eye movements were recorded in the dark by a magnetic search coil technique. The spatio-temporal organization of eye movements in the kitten has a prevailing vertical orientation and differs completely from that of the cat. In the kitten the amplitude of eye movements is smaller than in the cat and only a few movements are followed by fixation. It results, by correlating amplitude-peak velocity, that rapid eye movements in the awake kitten are saccades. From our results we conclude that the eye movements in the kitten and in the cat differ in many aspects and that the visual system is responsible for the development of the correct oculomotor behaviour.

Aging↗
PubMed2000

[Cognitive dysfunction in schizophrenia--analysis using exploratory eye movements].

Studies of exploratory eye movements on patients with schizophrenia were reviewed. Cognitive dysfunction in schizophrenia was examined from two aspects: the schema by Neisser, and the reaction to an object or a stimulus using exploratory eye movements. The schema by which subjects view an object with a spacial spread and with a sequence of time was disturbed in schizophrenia patients, and this schema was not changeable in the response to various conditions in these patients compared with non-schizophrenic individuals. The responsive search score (RSS) in schizophrenia was extracted as the disturbance of schema in the interpersonal setting. The lowering of RSS was a common feature in many patients with schizophrenia and remarkably reflects a trait of schizophrenia. We discussed a relationship between the RSS and other trait markers in schizophrenia, and it was suggested that the concept of "Disturbance of Schema" can explain abnormal results of other indicators and can lead us to understand several theories of cognitive dysfunction in schizophrenia.

Cognition Disorders↗
PubMed1997

EMDR minus eye movements equals good psychotherapy.

Eye Movement Desensitization and Reprocessing (EMDR) is a therapy roughly equal in efficacy to others currently available. It is argued that this treatment method is efficacious independent of the value of its component parts (e.g., eye movements) and is successful because it applies common and generally accepted principles of psychotherapy. Ten curative principles of this procedure are discussed as reflective of sound psychotherapy practice. It is hoped that an understanding of this therapy from the perspective of the practice and theory of psychotherapy will assist in its study.

Abreaction↗
PubMed1983

Abnormal patterns of normal eye movements in schizophrenia.

The multilevel control of eye movements for the researcher in the schizophrenic disease process includes the saccadic trajectory, the dual mode tracking system, and schematically directed eye movements in fixation, in scanpaths, and other looking strategies, and in reading. Coordination of eye movements with head movement in gaze and sensory consequences and concomitants of eye movements round out the picture. Recent studies with precise bioengineering instrumentation have defined two abnormal patterns of eye movements--saccadic intrusions and saccadic "smooth" pursuit. Although these signs are not pathognomonic, they raise interesting questions concerning the relationship of these eye movements to the schizophrenic disease process.

Attention↗
PubMed1996

The cyclic alternating pattern plays a gate-control on periodic limb movements during non-rapid eye movement sleep.

Periodic limb movements in sleep (PLMS) is a disorder characterized by a cyclic pattern of motor phenomena and EEG changes (mostly arousals), both recurring at approximately 20- to 40-s intervals. The periodicity of the PLMS phenomena recalls the physiological EEG arousal rhythm of non-rapid eye movement (NREM) sleep known as the cyclic alternating pattern (CAP). During CAP, arousals and arousal-equivalent features do not appear as isolated events but periodically intrude (phase A) between intervals of background EEG activity (phase B). Though the A phases can be expressed by a variety of EEG patterns, each with a different arousal impact on polygraphic parameters, overall CAP is a sequence of biphasic cycles reflecting a condition of unstable sleep. Twelve middle-aged PLMS subjects complaining of poor sleep were polygraphically compared with 12 age-matched and gender-matched healthy volunteers (controls). With respect to controls, the PLMS recordings showed an enhancement of the more powerful arousals and presented significantly increased amounts of CAP time (+45 min) and CAP rate (+15%). Of all the jerks detected in NREM sleep, 92% occurred in CAP, with the great majority of limb movements (96%) associated with phase A. Ninety-four percent of the nocturnal jerks coupled with phase A started jointly with the onset of the phase or when the latter had already begun. In particular, most of the myoclonic events (67%) occurred in the first 2.5 s of the A phase. The CAP cycles coupled with periodic movements were significantly longer than those without motor events (+6.4 s). Compared to the American Sleep Disorders Association's rules for scoring EEG arousals, the CAP framework offers a more extensive insight into PLMS. In effect, the present study indicates an entrainment of nocturnal myoclonus by means of CAP and sheds light on the complex interactions between arousal mechanisms and motor phenomena during sleep.

Adult↗
PubMed2004

The effect of plausibility on eye movements in reading.

Readers' eye movements were monitored as they read sentences describing events in which an individual performed an action with an implement. The noun phrase arguments of the verbs in the sentences were such that when thematic assignment occurred at the critical target word, the sentence was plausible (likely theme), implausible (unlikely theme), or anomalous (an inappropriate theme). Whereas the target word in the anomalous condition provided evidence of immediate disruption, the effect of the target word in the implausible condition was considerably delayed. The results thus indicate that when a word is anomalous, it has an immediate effect on eye movements, but that the effect of implausibility is not as immediate.

Attitude↗
PubMed1997

[Detection of cortical activities on eye movement using functional magnetic resonance imaging].

Cortical activity during eye movement was examined with functional magnetic resonance imaging. Horizontal saccadic eye movements and smooth pursuit eye movements were elicited in normal subjects. Activity in the frontal eye field was found during both saccadic and smooth pursuit eye movements at the posterior margin of the middle frontal gyrus and in parts of the precentral sulcus and precentral gyrus bordering the middle frontal gyrus (Brodmann's areas 8, 6, and 9). In addition, activity in the parietal eye field was found in the deep, upper margin of the angular gyrus and of the supramarginal gyrus (Brodmann's areas 39 and 40) during saccadic eye movement. Activity of V5 was found at the intersection of the ascending limb of the inferior temporal sulcus and the lateral occipital sulcus during smooth pursuit eye movement. Our results suggest that functional magnetic resonance imaging is useful for detecting cortical activity during eye movement.

Adult↗
PubMed1986

Processing of sentences in aphasia as assessed by eye-movement recordings.

The eye-movements of nine aphasic and nine nonaphasic control patients were recorded while they were looking at slides, containing eight words, selected from four different linguistic categories (nouns, verbs, adjectives, and adverbs). The task was to construct a 4-word sentence. The aphasic patients produced fewer syntactically and semantically correct sentences. Both aphasics and controls used more nouns than adverbs in their sentences. The eye-movement patterns revealed no statistically significant differences between the two groups in terms of fixation time per word category or in terms of fixation time per visual hemispace. Implications for a linguistic theory of sentence processing are discussed.

Aged↗
PubMed1984

Frontal lobe dysfunctions in schizophrenia--I. Eye movement impairments.

The phenomena of eye movement impairments in schizophrenia are interpreted in this paper, Part I of a two-paper series, in the context of neural mechanisms of attention and eye movement control. The predominant pattern of attention and eye movement impairment in schizophrenia--a disruption of smooth pursuit by saccadic intrusions--is consistent with a disinhibition of saccades. This disinhibition may be related to a dysfunction of frontal eye field mechanisms involved in feedback regulation of saccades and smooth pursuit during visual tracking. A second, less specific type of smooth pursuit impairment consists of saccadic substitution, and may be interpreted in terms of a dysfunction of temporo-parietal mechanisms of task-engagement.

Attention↗
PubMed1989

Effects of phosphor persistence on perception and the control of eye movements.

When a rapid eye movement (saccade) is made across material displayed on cathode ray tube monitors with short-persistence phosphors, various perceptual phenomena occur. The phenomena do not occur when the monitor has a long-persistence phosphor. These phenomena were observed for certain spatial arrays, their possible physiological basis noted, and their effect on the control of eye movements examined. When the display consisted simply of two dots, and a saccade was made from one to the other, a transient ghost image was seen just beyond the destination target. When the display consisted of vertical lines, tilting and displacement of the lines occurred. The phenomena were more intrusive for the latter display and there was a significant increase in the number of corrective saccades. These results are interpreted in terms of the effects of fluctuating illumination (and hence phosphor persistence) on saccadic suppression.

Adult↗