Comments on "Smooth-pursuit eye movements: A comparison of two measurement techniques" by Lindsey, Holzman, Haberman, and Yasillo.

D. T. Lindsey et al (1978) reported that the qualitative comparability of smooth-pursuit eye movement recordings derived from EOG and infrared reflection techniques is high. When Ss were examined who displayed what P. S. Holzman et al (1978) have labeled in their schizophrenic patients a "Type II" tracking dysfunction, there was poor correspondence between the 2 methods, indicating that the spikes evident in Type II tracking do not stem from movement of the eyes. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clinical, neuropsychological, and brain structural correlates of smooth-pursuit eye tracking performance in chronic schizophrenia.

Examined the relation of smooth-pursuit eye tracking dysfunction to neuropsychological performance, brain structural anomalies, and clinical state in a sample of 61 patients with chronic schizophrenia. No association was found between impaired pursuit oculomotion and measures of chronicity or clinical state. Likewise, no association emerged between eye tracking integrity and brain structural anomalies. Patients with dysfunctional eye tracking were more likely to have impaired performance on tests that assess frontal lobe functioning. In addition, they had more negative symptoms and a relative absence of positive symptoms. Because negative symptoms are often found among patients wih frontal lobe impairment, their association with abnormal eye tracking provides converging support for the hypothesis that the cortical locus of deviant smooth-pursuit eye tracking is in the frontal lobes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Smooth pursuit in 1- to 4-month-old human infants

The ability of human infants < or = 4 months of age to pursue objects smoothly with their eyes was assessed by presenting small target spots moving with hold-ramp-hold trajectories at ramp velocities of 4-32 deg/sec. Infants as young as 1 month old followed such target motions with a combination of smooth-pursuit and saccadic eye movements interrupted occasionally by periods when the eyes remained stationary. The slowest targets produced variable performance, but targets moving 8-32 deg/sec produced consistent pursuit behavior, even in the youngest infants. By the fourth month, eye-movement latency decreased and smooth-pursuit gain and the percentage of smooth pursuit per trial increased for all target velocities, though these measures had not yet reached adult levels.     

The effect of a moving distractor on the initiation of smooth-pursuit eye movements

As a step toward understanding the mechanism by which targets are selected for smooth-pursuit eye movements, we examined the behavior of the pursuit system when monkeys were presented with two discrete moving visual targets. Two rhesus monkeys were trained to select a small moving target identified by its color in the presence of a moving distractor of another color. Smooth-pursuit eye movements were quantified in terms of the latency of the eye movement and the initial eye acceleration profile. We have previously shown that the latency of smooth pursuit, which is normally around 100 ms, can be extended to 150 ms or shortened to 85 ms depending on whether there is a distractor moving in the opposite or same direction, respectively, relative to the direction of the target. We have now measured this effect for a 360 deg range of distractor directions, and distractor speeds of 5-45 deg/s. We have also examined the effect of varying the spatial separation and temporal asynchrony between target and distractor. The results indicate that the effect of the distractor on the latency of pursuit depends on its direction of motion, and its spatial and temporal proximity to the target, but depends very little on the speed of the distractor. Furthermore, under the conditions of these experiments, the direction of the eye movement that is emitted in response to two competing moving stimuli is not a vectorial combination of the stimulus motions, but is solely determined by the direction of the target. The results are consistent with a competitive model for smooth-pursuit target selection and suggest that the competition takes place at a stage of the pursuit pathway that is between visual-motion processing and motor-response preparation.     

Specific phosphatidylethanolamine dependence of Serratia marcescens cytotoxin activity

A region of dorsomedial frontal cortex (DMFC) has been implicated in planning and executing saccadic eye movements; hence it has been referred to as a supplementary eye field (SEF). Recently, activity related to executing smooth-pursuit eye movements has been recorded from the DMFC, and microstimulation here has been shown to evoke smooth eye movements. This report documents neuronal activity present in smooth-pursuit tasks where the predictability of target motion was manipulated. The activity of many neurons in the DMFC reached a peak when a predictable change in target motion occurred. Furthermore, the peak activity of some cells was systematically shifted by manipulating the duration of the target event, indicating that the network these neurons were in could learn the temporal characteristics of new target motion. Finally, the activity of most neurons tested was greater when target motion was predictable than when it was unpredictable. The results suggest that the DMFC participates in planning smooth-pursuit eye movements based on past stimulus history.     

Smooth-pursuit eye tracking in first-episode psychotic patients and their relatives.

In order to determine the specificity of smooth-pursuit eye tracking dysfunction to schizophrenia (SC) and the prevalences of dysfunction among functionally psychotic and normal individuals, the authors investigated pursuit tracking in a large sample of psychotic patients, normal Ss, and 1st-degree relatives (N?=?482). Ss were recruited as part of an epidemiological study of 1st-episode psychosis that used a broadly based referral network to identify all cases in a major metropolitan area over a 2.5-yr period. Ss received diagnoses of SC, schizophreniform disorder, psychotic mood disorder, and paranoid or other psychotic disorder based on the Diagnostic and Statistical Manual of Mental Disorders (DSM-III). The distribution of tracking performance was bimodal for the SC Ss and their relatives, perhaps reflecting major gene action. Moreover, poor tracking ran in families. Pursuit tracking dysfunction was relatively specific to SC Ss and their relatives and occurred infrequently in other psychotic Ss and normal Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eye tracking in patients with unipolar and bipolar affective disorders in remission.

Examined patients (20–66 yrs old) with a history of recurrent affective disorder on a variety of smooth-pursuit and saccadic eye-tracking tasks and on psychomotor analogs of these tasks. The 25 unipolar and 24 bipolar Ss were compared to 24 schizophrenics; all Ss were in remission. Results indicate that the performance of the 2 affective-disorder groups was not significantly different from that of the controls on any of these tasks. Smooth-pursuit tracking error was greater for Ss receiving Li and for those with a higher frequency of prior episodes of the disorder. When the pursuit eye movements of these Ss were compared to those of the schizophrenics, the latter produced more tracking error than both affective-disorder groups but significantly so only with respect to unipolar Ss. Although findings are consistent with the interpretation that tracking dysfunction is not a trait characteristic of affective disorders, further investigations contrasting remitted patients with bipolar and schizophrenic disorders are needed to determine the specificity of deviant tracking to schizophrenia. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The value of electro-oculography for the diagnosis of tapeto-retinal degenerations

The particular value of the EOG for diagnosis and prognosis has been demonstrated with the findings and case histories of seven patients. We have shown (1) that the EOG in connection with the ERG has contributed decisively to the differentiation of numerous types of tapeto-retinal dystrophies; (2) that the EOG is, as a rule, very valuable in distinguishing between tapeto-retinal dystrophies and flourishing or healed chorioretinitis, and (3) the different values of the other examination methods (visual field, colour vision tests, dark adaptation, angiography) in comparison with the electrophysiological methods. We have used the same methods as were used in previous examinations.     

Microbial populations of Botrytis cinerea-inoculated strawberry fruit exposed to four volatile compounds

OBJECTIVE: The authors tested the hypothesis that eye tracking disorder in schizophrenia is associated with neurological signs. METHOD: The subjects were 93 normal comparison subjects and 59 schizophrenic patients. They were evaluated with the Neurological Evaluation Scale, a standardized rating instrument that assesses sensory integration, motor coordination, sequencing of complex motor acts, and other neurological signs. Also, the schizophrenic patients' smooth-pursuit eye movements were tested in response to a 0.3-Hz sinusoidal target by means of infrared oculography. They were divided into those with (N=18) and without (N=41) eye tracking disorder by using a previously described method, which was based on mixture analysis of the distribution of position root mean square error. RESULTS: The patients with eye tracking disorder had significantly worse performance than the patients without eye tracking disorder with respect to sensory integration, and the effect size was moderate to large. In comparison with the normal subjects, both patient subgroups had significantly worse performance on all of the Neurological Evaluation Scale subscales. CONCLUSIONS: Although neurological signs are present generally in schizophrenia, poor sensory integration is particularly pronounced in patients with eye tracking disorder. A review of the literature shows that the two abnormalities have strikingly similar patterns of validators, including 1) familial aggregation, 2) premorbid presence, 3) syndromal specificity, 4) trait status, and 5) association with the deficit syndrome. Poor sensory integration and eye tracking disorder in schizophrenia may be various manifestations of a common, underlying pathophysiological process.     

Eye-hand coordination: Oculomotor control in rapid aimed limb movements.

Three experiments are reported in which Ss produced rapid wrist rotations to a target while the position of their eyes was being monitored. In Experiment 1, Ss spontaneously executed a saccadic eye movement to the target around the same time as the wrist began to move. Experiment 2 revealed that wrist-rotation accuracy suffered if Ss were not allowed to move their eyes to the target, even when visual feedback about the moving wrist was unavailable. In Experiment 3, wrist rotations were equally accurate when Ss produced either a saccadic or a smooth-pursuit eye movement to the target. However, differences were observed in the initial-impulse and error-correction phases of the wrist rotations, depending on the type of eye movement involved. The results suggest that aimed limb movements use information from the oculomotor system about both the static position of the eyes and the dynamic characteristics of eye movements. Furthermore, the information that governs the initial impulse is different from that which guides final error corrections. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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.     

Implications of comorbidity for genetic studies of bipolar disorder: P300 and eye tracking as biological markers for illness

In large families with affective illness, identification of a biological variable is needed that reflects brain dysfunction at an earlier point than symptom development. Eye movement disorder, a possible vulnerability marker in schizophrenia, is less clearly associated with affective illness, although a subgroup of affective disorders shows smooth-pursuit eye movement disorder. The auditory P300 event-related potential may be a useful marker for risk to schizophrenia, but a role in bipolar illness is less certain. The distribution of these two biological variables and their association with symptoms in two multiply affected bipolar families is described. In a single, five-generation family identified for linkage studies through two bipolar I (BPI) probands, 128 members (including 20 spouses) were interviewed. The 108 related individuals had diagnoses of BPI (7), bipolar II (2), cyclothymia (3), or major depressive disorder (19). Eight others had generalised anxiety (1), minor depression (5), intermittent depression (1), or alcoholism (1). Sixty-nine subjects had no psychiatric diagnosis. P300 latency (81) and eye tracking (71) were recorded from a subgroup of relatives within the pedigree. Eye tracking was abnormal in 11 of 71 relatives (15.5%) and was bimodally distributed. In these 11 relatives, clinical diagnoses included minor depression (1), alcoholism (1) and generalised anxiety disorder (1). P300 latency was normally distributed and did not differ from controls. In a second family in which five of seven siblings have BPI illness, P300 latency and eye movement disorder were found in affected relatives and in some unaffected offspring. In these large families, clinical diagnoses of general anxiety, alcoholism and minor depression, when associated with eye tracking abnormality, may be considered alternative clinical manifestations of the same trait that in other relatives is expressed as bipolar illness.     

Temporal properties of visual motion signals for the initiation of smooth pursuit eye movements in monkeys

1. Our goal was to assess whether visual motion signals related to changes in image velocity contribute to pursuit eye movements. We recorded the smooth eye movements evoked by ramp target motion at constant speed. In two different kinds of stimuli, the onset of target motion provided either an abrupt, step change in target velocity or a smooth target acceleration that lasted 125 ms followed by prolonged target motion at constant velocity. We measured the eye acceleration in the first 100 ms of pursuit. Because of the 100-ms latency from the onset of visual stimuli to the onset of smooth eye movement, the eye acceleration in this 100-ms interval provides an estimate of the open-loop response of the visuomotor pathways that drive pursuit. 2. For steps of target velocity, eye acceleration in the first 100 ms of pursuit depended on the "motion onset delay," defined as the interval between the appearance of the target and the onset of motion. If the motion onset delay was > 100 ms, then the initial eye movement consisted of separable early and late phases of eye acceleration. The early phase dominated eye acceleration in the interval from 0 to 40 ms after pursuit onset and was relatively insensitive to image speed. The late phase dominated eye acceleration in the interval 40-100 ms after the onset of pursuit and had an amplitude that was proportional to image speed. If there was no delay between the appearance of the target and the onset of its motion, then the early component was not seen, and eye acceleration was related to target speed throughout the first 100 ms of pursuit. 3. For step changes of target velocity, the relationship between eye acceleration in the first 40 ms of pursuit and target velocity saturated at target speeds > 10 degrees /s. In contrast, the relationship was nearly linear when eye acceleration was measured in the interval 40-100 ms after the onset of pursuit. We suggest that the first 40 ms of pursuit are driven by a transient visual motion input that is related to the onset of target motion (motion onset transient component) and that the next 60 ms are driven by a sustained visual motion input (image velocity component). 4. When the target accelerated smoothly for 125 ms before moving at constant speed, the initiation of pursuit resembled that evoked by steps of target velocity. However, the latency of pursuit was consistently longer for smooth target accelerations than for steps of target velocity.(ABSTRACT TRUNCATED AT 400 WORDS)     

Distractor interference during smooth pursuit eye movements.

When 2 targets for pursuit eye movements move in different directions, the eye velocity follows the vector average (S. G. Lisberger & V. P. Ferrera, 1997). The present study investigates the mechanisms of target selection when observers are instructed to follow a predefined horizontal target and to ignore a moving distractor stimulus. Results show that at 140 ms after distractor onset, horizontal eye velocity is decreased by about 25%. Vertical eye velocity increases or decreases by 1°/s in the direction opposite from the distractor. This deviation varies in size with distractor direction, velocity, and contrast. The effect was present during the initiation and steady-state tracking phase of pursuit but only when the observer had prior information about target motion. Neither vector averaging nor winner-take-all models could predict the response to a moving to-be-ignored distractor during steady-state tracking of a predefined target. The contributions of perceptual mislocalization and spatial attention to the vertical deviation in pursuit are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Initiation of disjunctive smooth pursuit in monkeys: evidence that Hering's law of equal innervation is not obeyed by the smooth pursuit system

Monkeys generated disjunctive smooth pursuit eye movements when they tracked visual targets that moved toward or away from them. Eye acceleration was computed during the initial 100 msec of pursuit (the open-loop interval) for various target trajectories. The initial acceleration of either eye was a function of the target's motion with respect to that eye, regardless of whether or not the pursuit was conjugate or disjunctive, or performed with one eye occluded. Eye movements produced by fusional vergence could be separated temporally from eye movements produced by smooth pursuit using step-ramp paradigms. The separation of the two responses demonstrates that the fusional vergence system operates in parallel with the smooth pursuit system, presumably to minimize disparity, but not to generate disjunctive components of smooth pursuit eye movements.     

The correlation between changes in EEG and eye movement (EOG) accompanied by lowered arousal level

We investigated the correlation between the components of spontaneous eye movement (EOG) and EEG in six healthy individuals. The study was conducted in three periods; from the resting to drowsy stage, from the drowsy to spontaneous awakening stage, and in the forced waking stage. EEG, as registered from bipolar electrodes attached between the left parietal region (P3) and the left occipital region (O1), was monitored continuously by the FFT method with a segment of 12.8 seconds. Rapid eye movement and slow eye movement were observed simultaneously. In conclusion, even when the arousal level varies considerably, there is a close correlation between frequency of rapid eye movement and EEG patterns of 10.16 integral of 10.94 Hz & 17.97 integral of 19.53 Hz (simple correlation p < 0.01). Additionally, during the forced waking period (after stage 2), delta and theta bands increased in cases along with sleepiness. Even if the depth of sleep was the same, one's mood upon awakening was determined by the frequency of slow waves before awakening.     

Role of the oculomotor vermis in generating pursuit and saccades: effects of microstimulation

We studied the eye movements evoked by applying small amounts of current (2-50 microA) within the oculomotor vermis of two monkeys. We first compared the eye movements evoked by microstimulation applied either during maintained pursuit or during fixation. Smooth, pursuitlike changes in eye velocity caused by the microstimulation were directed toward the ipsilateral side and occurred at short latencies (10-20 ms). The amplitudes of these pursuitlike changes were larger during visually guided pursuit toward the contralateral side than during either fixation or visually guided pursuit toward the ipsilateral side. At these same sites, microstimulation also often produced abrupt, saccadelike changes in eye velocity. In contrast to the smooth changes in eye velocity, these saccadelike effects were more prevalent during fixation and during pursuit toward the ipsilateral side. The amplitude and type of evoked eye movements could also be manipulated at single sites by changing the frequency of microstimulation. Increasing the frequency of microstimulation produced increases in the amplitude of pursuitlike changes, but only up to a certain point. Beyond this point, the value of which depended on the site and whether the monkey was fixating or pursuing, further increases in stimulation frequency produced saccadelike changes of increasing amplitude. To quantify these effects, we introduced a novel method for classifying eye movements as pursuitlike or saccadelike. The results of this analysis showed that the eye movements evoked by microstimulation exhibit a distinct transition point between pursuit and saccadelike effects and that the amplitude of eye movement that corresponds to this transition point depends on the eye movement behavior of the monkey. These results are consistent with accumulating evidence that the oculomotor vermis and its associated deep cerebellar nucleus, the caudal fastigial, are involved in the control of both pursuit and saccadic eye movements. We suggest that the oculomotor vermis might accomplish this role by altering the amplitude of a motor error signal that is common to both saccades and pursuit.     

Retinal masking during pursuit eye movements: Implications for spatiotopic visual persistence.

White (1976) reported that presentation of a masking stimulus during a pursuit eye movement interfered with the perception of a target stimulus that shared the same spatial, rather than retinal, coordinates as the mask. This finding has been interpreted as evidence for the existence of spatiotopic visual persistence. We doubted White's results because they implied a high degree of position constancy during pursuit eye movements, contrary to previous research, and because White did not monitor Ss' eye position during pursuit; if White's Ss did not make continuous pursuit eye movements, it might appear that masking was spatial when in fact it was retinal. We attempted to replicate White's results and found that when eye position was monitored to ensure that subjects made continuous pursuit movements, masking was retinal rather than spatial. Ss' phenomenal impressions also indicated that retinal, rather than spatial, factors underlay performance in this task. The implications of these and other results regarding the existence of spatiotopic visual persistence are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quantitative evaluation of saccadic and smooth pursuit eye movements. Is it reliable?

PURPOSE: The authors evaluated the reliability of the coefficients of the (1) amplitude/duration and (2) amplitude/peak velocity relationships of the mean precision values and the mean latency values (saccadic eye movements) and the coefficients of the target velocity/gain relationship (smooth pursuit eye movements). They computed test-retest maximum variability limits for these parameters. METHODS: After a 1-week interval, saccadic and smooth pursuit eye movements were recorded twice from 20 healthy subjects; 12 of these subjects underwent a third recording session. The estimate of the intraclass coefficient of reliability, R, was adopted to evaluate the reliability of eye movement quantitative analysis. RESULTS: The data demonstrated that the reliability was fairly good for the amplitude/peak velocity relationship, was good for the precision, and was excellent for the amplitude/duration, the target velocity/gain relationships, and the latency. CONCLUSIONS: Quantitative analysis of both saccadic and smooth pursuit eye movements is reliable. One statistic used to estimate reliability, ie, the within-subjects mean square value, also enables the determination of test-retest normal variability values for both the variances and the differences of measurements.     

Familial prevalence and coaggregation of schizotypy indicators: A multitrait family study.

Schizophrenic probands (n?=?17), their 1st-degree relatives (n?=?61), and medically and psychiatrically screened normal control Ss (n?=?18) were studied with structured interviews for Diagnostic and Statistical Manual of Mental Disorders (DSM-III) Axis I disorders and schizotypal personality disorder, questionnaire measures of schizotypy, measures of smooth-pursuit eye movement dysfunction, and attention dysfunction. Schizophrenic Ss scored abnormally on essentially all measures. Relatives differed significantly from control Ss on most measures. Correlational analyses indicate that many characteristics tested in these measures run together in families. The data are consistent with the hypothesis that a single vulnerability dimension or typology, presumably in part genetically transmitted, may account for phenotypically distinct abnormalities. These traits, taken together, may have joint usefulness for identifying persons with a predisposition to schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)