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PubMed2001

Eye-movement recording in freely moving animals.

A new method is described for precise recording of eye movements in freely moving animals using Hall-effect devices. This inexpensive system, of small size and low weight, allows the analysis of horizontal and vertical components of saccadic eye movements, optokinetic nystagmus, slow tracking movements, eye vergence, etc., in unrestrained animals. A set of Hall-effect devices mounted in the skull is used to sense variations in the position of high-power miniature magnets fixed to the eye sclera. The output of the Hall-effect devices is amplified by operational amplifiers and collected through an analog-to-digital converter to be displayed on-line in a personal computer and stored for later analysis by specific software. Some examples of simultaneous body- and eye-movement recordings obtained in freely moving goldfish in different experimental situations are presented. This method would be useful in the recording of eye and gaze movements under natural conditions and for behavioural studies in freely moving animals.

Animals↗
PubMed1984

The effect of expectations on slow oculomotor control--IV. Anticipatory smooth eye movements depend on prior target motions.

Prior work had shown that smooth eye movements depend both on the motion of the target on the retina and on the subject's expectations about future target motion (Kowler and Steinman, 1979a,b). Effects of expectation cannot be eliminated by making target motions unpredictable (Kowler and Steinman, 1981). The experiment reported here shows that effects of expectations on smooth eye movement depend in a lawful way on the history of prior target motions. Anticipatory smooth eye movements (involuntary drifts in the direction of future target motion) were measured while subjects fixated a stationary target that was expected to step in an unpredictable direction (right or left). Anticipatory smooth eye movement velocity depended on the sequence of steps in prior trials, e.g. velocity was faster to the right when the prior steps were to the right. The influence of prior steps diminished the further back into the past the step occurred. Sequential dependencies were also observed for the saccades used to track the target steps. Anticipatory smooth eye movement velocity was predicted by a two-state Markov model developed by Falmagne et al. (1975) for similar sequential dependencies observed in a manual reaction-time task (button-pressing). The model uses the prior sequence of target motions to predict the subject's expectation, and assumes that the expectation determines anticipatory smooth eye movement velocity. The fit of the model to the data was good which shows that taking expectations into account is both necessary and feasible. Taking expectations into account, quantitatively, allows accurate predictions about smooth eye movement velocity when target motions are unpredictable.

Eye Movements↗
PubMed1985

Spontaneous eyeblinks elicited by vertical eye movements.

Two experiments were carried out to examine the relationship between eyeblinks and eye movements under a visual search task. Exp. I showed that the vertical eye movements brought about slightly more eyeblinks than the horizontal ones. In Exp. II, the vertical eye movements were accompanied with significantly more frequent eyeblinks than the horizontal ones. Upward saccadic eye movements especially were associated with the more frequent eyeblinks than the downward ones. These results suggested a possible relationship between the eyeblinks and Bell's phenomenon. However, the comparison of eyeblink rates between eye-movement and the no-eye-movement conditions in Exp. II indicated that in the latter condition eyeblinks were significantly more frequent than in the former condition. Some psychological factors were suggested as likely important determinants of the frequency of eyeblinks.

Adolescent↗
PubMed1986

The nature of reverse phase reflex eye movement.

The unusual phenomenon of reverse phase reflex eye movement was first described by Ishikawa. In this study the reflex frequency response was examined by electrooculography. In typical cases a reflex was observed by repeated forced duction up to 9 Hz. As a result it was postulated that proprioception is usually involved in reverse phase reflex eye movement, because visual eye movement cannot respond to a movement beyond 1 Hz. When the lag-times between the peaks of forced duction in one eye and those of the reflex movement in the other were measured, they were almost zero or even negative at high frequencies of forced duction as 6 and 9 Hz. This phase advance of the reflex movement was explained only when the receptor of the reflex had a dynamic response, because 90 degrees phase advance results in a reflex through such a receptor. The primary ending of muscle spindle represents such a receptor. The magician's forceps phenomenon as first discovered by Mitsui in exotropia is supposed to be a blocking reflex through the tendon organ. The transmission lag-times of both reflexes can be as short as 20 msec, but must be slightly longer to consider them to be monosynaptic.

Adolescent↗
PubMed1992

Recording eye movement during stepping in place with a CCD (charge-coupled device) imagesensor.

A new system for recording eye movements using a charge-coupled device (CCD) imagesensor in a video camera, in which less than 0.5 degree of horizontal and vertical eye movements can be recorded, was applied in 7 subjects. Eye movements were recorded while they stepped in place. We observed 5 normal subjects, a patient with horizontal and vertical oscillopsia during walking, and one with a chronic limp. In the normal adults, the amplitude of vertical eye movement was less than 0.5 degree, and the horizontal eye movement was less than 2 degrees. The mean amplitude of horizontal and vertical eye movements in the subject who limped was larger than that of normal subjects. The patient who complained of vertical oscillopsia during walking showed the largest amplitude of vertical eye movement among any subject tested. The vertical oscillopsia in the patient was due to the largest amplitude of vertical eye movement. This system for recording eye movements will be useful in analyzing the mechanism of gaze fixation during walking.

Adult↗
PubMed2006

Absence of rapid eye movement sleep behavior disorder in 11 members of the pallidopontonigral degeneration kindred.

BACKGROUND: Rapid eye movement sleep behavior disorder (RBD) is a parasomnia that is manifested by dream enactment behavior. The electrophysiologic substrate for RBD on polysomnography is rapid eye movement sleep without atonia. Rapid eye movement sleep behavior disorder likely stems from neuronal network dysfunction in the brainstem, although it is not yet clear which specific networks are involved. Rapid eye movement sleep behavior disorder is often associated with the sporadic synucleinopathies but rarely associated with the sporadic tauopathies. There are no reports on the possible association of rapid eye movement sleep without atonia and RBD with any familial tauopathy. OBJECTIVE: To characterize the clinical sleep and polysomnography features in a kindred with a familial tauopathy. METHODS: We performed standard polysomnography in 11 members of the pallidopontonigral degeneration kindred irrespective of any sleep-related complaints. Neuropathologic findings were analyzed in those who subsequently underwent autopsy. RESULTS: Six affected and 5 genealogically at-risk family members were studied. None of the 11 had a history of dream enactment behavior. Nine of the 11 members attained sufficient rapid eye movement sleep on polysomnography, and the electrophysiologic features of rapid eye movement sleep without atonia and behavioral manifestations of RBD were absent in all subjects. Neuropathologic examination of 4 affected individuals revealed marked nigral degeneration in 3 along with mild degenerative changes in the locus coeruleus, pontine nuclei and tegmentum, and medullary tegmentum. CONCLUSIONS: These findings argue against nigral degeneration being the primary cause of RBD. The absence of the historical, electrophysiologic, and behavioral manifestations of RBD in this kindred provides further evidence that RBD is rare in the sporadic and familial tauopathies. The difference in frequencies of RBD associated with the synucleinopathies compared with the tauopathies suggests differences in the selective vulnerability of brainstem circuits between the synucleinopathies and tauopathies.

Adult↗
PubMed1994

Differences in eye movements and reading problems in dyslexic and normal children.

It has been suggested that eye movement abnormalities seen in dyslexics are attributable to their language problems. In order to investigate this claim, we studied eye movements in dyslexic children, during several non-reading tasks. Dyslexic children were compared to normal and backward readers on measures of fixation, vergence amplitude, saccade and smooth pursuit. The results were compared to the children's phonological ability. Dyslexic children (n = 26) had significantly worse eye movement stability during fixation of small targets than normal children (n = 39). Vergence amplitudes were lower for dyslexics than for controls. A qualitative assessment of saccadic eye movements revealed that dyslexics exhibit fixation instability at the end of saccades. Assessment of smooth pursuit revealed poor smooth pursuit in the dyslexic group, particularly when pursuing a target moving from left to right. Dyslexic children also performed significantly worse than normal children on a test of phonological awareness (Pig Latin). Eye movement results were studied in the light of the findings on phonological awareness: dyslexics with small vergence amplitudes also always have poor phonemic awareness. However, poor fixation control is found in dyslexics with or without poor phonological ability. The backward reading children performed similar to the dyslexics on all tests, suggesting that the deficiencies observed in this study are not specific to children with dyslexia. The problems experienced by the children (revealed by a questionnaire) are in agreement with those measured in terms of eye movement recordings and phonemic awareness. Sex, handedness, IQ or the presence of attention deficit disorder (ADD) did not appear to influence the children's performances on any of the eye movement tasks. The presence of oculomotor abnormalities in a non-reading task strongly suggests that the underlying deficit in the control of eye movements seen in dyslexics is not caused by language problems alone.

Attention Deficit Disorder with Hyperactivity↗
PubMedDate not supplied

Automatic attention cueing through eye movement in 2-year-old children with autism.

Automatic attention cueing by perceived changes in gaze direction was studied in 2-year-old children with autism and typically developing (TD) controls using a visual attention cueing paradigm. In Experiments 1 and 2 the cue consisted of an eye movement (Eyes) and a nonbiological movement (SimEyes), respectively. The results suggest that visual attention in children with autism and their TD counterparts is cued by perceived eye movement. Thus, although in naturalistic situations toddlers with autism do not follow the gaze of others, they are sensitive to directional cues inherent in eye movement. Cue-specific differences in performance related to the level of engagement and cue-processing time may suggest reliance on different underlying strategies for gaze processing in autism.

Attention↗
PubMed1982

Defense mechanisms, somatic symptoms and lateral eye movements in females.

Research with male subjects has related lateral eye movements to preferred mode of defense and psychosomatic symptoms. However, previous research has systematically excluded female subjects which precluded the investigation of hypothesized but not yet confirmed patterns of sex differences. The present study examined the relationship between lateral eye movements, psychological defenses, and somatic symptoms in females. Lateral eye-movement patterns were assessed for 32 female undergraduate students, who were then administered the Defense Mechanism Inventory and Body Symptom Questionnaire. The data indicated no relationship between eye-movement patterns and either defensive style or somatic symptoms. Previous concerns about using female subjects in lateral eye-movement studies appear justified as this may decrease the probability of finding effects of lateralization.

Adult↗
PubMed2005

Is emotional content obtained from parafoveal words during reading? An eye movement analysis.

An eye-movement-contingent display change technique was employed to study whether adult readers extract semantic information from parafoveal words during reading. Three types of parafoveal preview conditions were contrasted: an emotional word, a neutral word, and an identical word condition. To have a maximally effective parafoveal manipulation, high-arousal emotional words (sex- and threat-related and curse words) were used as parafoveal previews. Readers' eye fixation patterns around the target word revealed no evidence for parafoveal semantic processing. Furthermore, the pupil size showed no signs for an emotional response triggered by an emotional word previewed parafoveally. These results are consistent with the view that, as a rule, only the fixated word is processed to a semantic level during reading.

Affect↗
PubMed2003

Depth from motion parallax scales with eye movement gain.

Recent findings suggest that the slow eye movement system, the optokinetic response (OKR) in particular, provides the extra-retinal signal required for the perception of depth from motion parallax (Nawrot, 2003). Considering that both the perception of depth from motion parallax (Ono, Rivest & Ono, 1986; Rivest, Ono & Saida, 1989) and the eye movements made in response to head translations (Schwarz & Miles 1991; Paige, Telford, Seidmen, & Barnes, 1998) appear to scale with viewing distance, changes in perceived depth from motion parallax were studied as a function of viewing distance. If OKR is used in the perception of depth from motion parallax, a change in the OKR signal, caused by a change in viewing distance, should accompany a change in perceived depth from motion parallax. Over a range of viewing distances, binocular stereopsis was used to index perceived depth from motion parallax. At these viewing distances the gain of the OKR portion of the compensatory eye movement was also determined. The results show that the change in OKR gain is mirrored by the change in perceived depth from motion parallax as viewing distance increases. This suggests that the OKR eye movement signal serves an important function in the perception of depth from motion.

Depth Perception↗
PubMed2003

Perceived slant from Werner's illusion affects binocular saccadic eye movements.

We examined whether binocular saccadic eye movements are determined solely by disparity-defined slant or whether they are influenced by both disparity-defined and perceived slant. The Werner illusion was used to distinguish a plane's disparity-defined slant from its perceived slant. Three subjects viewed a horizontally elongated test strip that was flanked vertically by two planes. The perceived slant of the test strip depended on the slant of the flanking planes. Subjects estimated the perceived slant of the test strip by adjusting the angle between two lines in a symbolic top view. The saccadic eye movements between targets on the test strip were recorded both with visual feedback ("later saccades") and without visual feedback ("first saccades"). We calculated vergence differences for saccades between targets on the test strip (and for fixation on these targets). For each geometrical test strip slant we examined whether the vergence differences could be explained as an effect of perceived slant. This study shows that saccadic eye movements are determined predominantly by the disparity-defined slant, but they can be affected by perceived slant, particularly when multiple saccades are being made.

Adult↗
PubMed1990

[Characteristics of evoked potentials related to saccadic eye movements in man].

The exactness of saccadic eye movements to the right and to the left and changes in evoked potentials related to these eye movements were analyzed in 50 university students with marked righthandedness and normal vision, aged from 18 to 24 years (18 males, 32 females). The saccades to the left were found to be more exact than those to the right, which overshot the target in a significantly higher number of instances. In subjects with exact refixations the premotion activity in evoked potentials is of shorter duration, the spike potential has a lower amplitude and the lambda response a shorter latency in saccades to the left. The given changes are more pronounced above the right occipital region. In subjects with a higher number of correction saccades the differences between the two sides disappear in saccade related evoked potentials. The obtained results support the presumed important role of the right hemisphere or the left half of the visual field in organizing eye movements and in the integration mechanisms of eyemotion-visual perception in righthanded subjects.

Adolescent↗
PubMed1990

Orbital position and eye movement influences on visual responses in the pulvinar nuclei of the behaving macaque.

We studied the influences of eye movements on the visual responses of neurons in two retinotopically organized areas of the pulvinar of the macaque. Cells were recorded from awake, trained monkeys, and visual responses were characterized immediately before and after the animals made saccadic eye movements. A significant proportion of the cells were more responsive to stimuli around the time of eye movements than they were at other intervals. Other cells had response reduction. For some neurons, the change in excitability was associated with orbital position and not the eye movement. For other cells the change was present with eye movements of similar amplitude and direction but with different starting and ending positions. Here it appears that the eye movement is the important parameter. Other cells had effects related to both eye position and eye movements. In all cells tested, the changes in excitability were present when the experiments were conducted in the dark as well as in the light. This suggests that the mechanism of the effect is related to the eye position or eye movement and not visual-visual interactions. For about half of the neurons with modulations, the response showed facilitation for stimuli presented in the most responsive region of the receptive field but not for those at the edge of the field. For the other cells there was facilitation throughout the field. Thus, a gradient of modulation in the receptive field may vary among cells. These experiments demonstrate modulations of visual responses in the pulvinar by eye movements. Such effects may be part of the visual-behavioral improvements at the end of eye movements and/or contribute to spatial constancy.

Animals↗
PubMed1991

A syntactic analysis method for sinusoidal tracking eye movements.

A syntactic method for the recognition of sinusoidal eye movements is presented. The method is based on a piecewise transformation of an eye movement signal to strings of a formal language and use of a formal grammar which generates the formal language. Gain and phase parameters of sinusoidal eye movements between a stimulus and its response are computed after the recognition of eye movements and after removing corrective saccades from the transformed signal. The method is used at an otoneurological laboratory.

Diagnosis, Computer-Assisted↗
PubMed2005

Involvement of the central thalamus in the control of smooth pursuit eye movements.

During maintenance of smooth pursuit eye movements, the brain must keep track of pursuit velocity to reconstruct target velocity from motion of retinal images. Although a recent study showed that corollary discharge signals through the thalamus to the cortex are used for internal monitoring of saccades, it remains unknown whether signals in the thalamus also contribute to monitoring and on-line regulation of smooth pursuit. The present study sought possible roles of the thalamocortical pathways in pursuit by recording activities of single thalamic neurons and by analyzing the effects of local inactivation. Data showed that many neurons in the ventrolateral thalamus exhibited directional modulation during pursuit. Most neurons discharged before or during initiation of pursuit, and the firing rate was proportional to the speed of target motion in a preferred direction. When the tracking target was extinguished briefly during maintenance of pursuit, these neurons continued firing, indicating that they carried extra-retinal, eye movement signals. The majority of neurons showed no change in activity around the time of small catch-up saccades during pursuit but responded transiently to large (16 degrees) memory-guided saccades in the preferred pursuit direction. Local inactivation of the recording sites did not alter pursuit latency but reduced eye velocity modestly during initiation and maintenance of ipsiversive pursuit. The results suggest that the central thalamus lies within pathways that regulate and monitor smooth pursuit eye movements.

Animals↗
PubMed1989

Eye movements following cortical stimulation in the ventral bank of the anterior ectosylvian sulcus of the cat.

Eye movements were induced by stimulating the ventral bank of the anterior ectosylvian sulcus (AES) of chloralose-anesthetized cats. Intracortical microstimulation of this cortex evoked centering movements of both eyes. The latency of eye movement was 45 ms (range 40-60 ms) and the intensity of stimulation was 33 microA (range 20-45 microA). The evoked eye movements persisted after ablation of the classical frontal eye field of both sides. These results suggest that the ventral bank of the AES is involved in the control of eye movements.

Animals↗
PubMed1985

Alexithymia, hemisphericity, and conjugate lateral eye movements.

The conjugate lateral eye movements (CLEMs) of 102 university students were measured in conjunction with the administration of the Schalling-Sifneos Personality Scale, a self-report measure of alexithymia. There was a significant positive correlation between CLEM scores and alexithymia scores for all subjects, suggesting the existence of a relationship between right hemisphere activation and alexithymic characteristics. These results are discussed in terms of some theoretical models of alexithymia.

Adult↗