Exploratory Eye Movements Research Articles

A Life Span Study of Exploratory Eye Movements in Healthy Subjects: Gender Differences and Affective Influences

To evaluate age and gender differences as well as effects of affection, we examined exploratory eye movements. Exploratory eye movements were recorded in healthy subjects (57 women and 57 men) ranging from 9 to 74 years. All subjects were divided into three groups as pre puberty, young, and older adults to study the influences of age and gonadal hormones. Exploratory eye movements were analyzed for total eye scanning length (TESL), and total numbers of gaze points (TNGP) as subjects viewed neutral or affectively charged pictures. TESL and TNGP in older adults were significantly larger than that in both pre puberty and young adults for crying babies. TESL and TNGP in pre puberty were significantly smaller than that in both young and older adults for circles. TESL and TNGP in pre puberty were significantly smaller than that in older adults for smiling babies. Pre puberty and young adult of both genders for crying babies showed significantly shorter TESL than for when smiling babies. When viewing circles, young adult women had shorter TESL than men. TNGP in young adult women was smaller than in men for circles or crying babies. TNGP of young adult women in the visual right field was significantly smaller than in men. TNGP for crying babies was significantly smaller than that for smiling babies in young adults of both genders for the left field. Exploratory eye movements thus are a useful marker of visual cognitive function. Gender differences were limited to younger adults, suggesting influences of gonadal hormones.

Characteristics of emotional related cognitive function in schizophrenia evaluating by exploratory eye movements, and fMRI: Comparison with healthy subjects

Characteristics of emotional related cognitive function in schizophrenia evaluating by exploratory eye movements, and fMRI: Comparison with healthy subjects

Relationship between exploratory eye movements and brain morphology in schizophrenia spectrum patients

The exploratory eye movements of schizophrenia patients and their relatives have been shown to differ from those of patients without schizophrenia and healthy controls. However the mechanism of exploratory eye movement disturbances in schizophrenia patients remains elusive. We investigated the relationship between the exploratory eye movements and brain morphology in 39 schizophrenia spectrum patients. Voxel-based morphometric analysis on three-dimensional magnetic resonance imaging was conducted by means of statistical parametric mapping 99. The decrease in the responsive search score, which is the total number of sections on which the eyes fixed in response to questioning in a comparison task, was significantly correlated with the decreased gray matter in the right frontal eye field (rFEF) including the right supplementary eye field (rSEF), right parietal eye field (rPEF), and right inferior frontal region. These results suggest that disturbance in exploratory eye movement in schizophrenia spectrum patients may be related to neural network dysfunction in FEF, SEF and PEF, which are the eye movement related areas, and in the inferior frontal region that may be related to information organization.

Goal-Related Activity in V4 during Free Viewing Visual Search: Evidence for a Ventral Stream Visual Salience Map

Natural exploration of complex visual scenes depends on saccadic eye movements toward important locations. Saccade targeting is thought to be mediated by a retinotopic map that represents the locations of salient features. In this report, we demonstrate that extrastriate ventral area V4 contains a retinotopic salience map that guides exploratory eye movements during a naturalistic free viewing visual search task. In more than half of recorded cells, visually driven activity is enhanced prior to saccades that move the fovea toward the location previously occupied by a neuron's spatial receptive field. This correlation suggests that bottom-up processing in V4 influences the oculomotor planning process. Half of the neurons also exhibit top-down modulation of visual responses that depends on search target identity but not visual stimulation. Convergence of bottom-up and top-down processing streams in area V4 results in an adaptive, dynamic map of salience that guides oculomotor planning during natural vision.

Eye movements tell only half the story

Neglect due to right hemisphere injury, most commonly after stroke, continues to be a major cause of disability. Indeed, patients with neglect behave as if half of their world has ceased to exist. One means of improving the performance of patients with hemispatial neglect is to move stimuli into their body-centered ipsilesional space. Therefore, providing patients with 15 to 20-diopter Fresnel prisms might be simple means of shifting images to the normal side. To enhance the therapeutic effect of prisms, the subject can be trained to point straight ahead while wearing the prism. This procedure has been called prism adaptation. In this study, a subject with neglect used these prisms and was evaluated on two visual tasks before and after prism adaptation. Eye movements were recorded during the visual tasks. The authors demonstrated that while the exploratory eye movements of a patient with neglect were clearly shifted toward the left after prism adaptation, he still showed no awareness for the left side of the stimuli he was now actively exploring. The authors suggest that prism adaptation modulates functions of the parietal lobe, such as eye movement control, but fails to influence the underlying mechanisms of neglect.—Valérie Biousse

Significant linkage to chromosome 22q for exploratory eye movement dysfunction in schizophrenia.

A genome-wide scan for a locus responsible for exploratory eye movement (EEM), which is quantitative and can be disturbed in association with schizophrenia, was performed. A 10-cM resolution genome-wide linkage analysis of the EEM disturbance with 358 highly polymorphic microsatellite markers in 38 nuclear families with 122 members (38 probands, 47 sibs, and 37 parents) including 58 sib-pairs yielded the suggestive linkage to the GCT10C10 marker on chromosome 22q11.2 (LOD = 2.48). Dense mapping with additional markers around the GCT10C10 marker yielded evidence for significant linkage between EEM disturbance and markers D22S429 and D22S310 on chromosome 22q12.1 (LOD score of 4.63) with suggestive evidence for the chromosome region 22q11.2-q12.1. Our findings suggest that a relatively small number of loci may control the schizophrenia-related quantitative EEM trait. We believe that identifying gene(s) on chromosome 22q associated with the EEM phenotype may forward our understanding of the etiology of schizophrenia.

Determining vulnerability to schizophrenia in methamphetamine psychosis using exploratory eye movements.

Patients with methamphetamine (MAP) psychosis whose psychotic symptoms continued after MAP withdrawal were observed at Saitama Prefecture Government Psychiatric Hospital. The purpose of the present study was to ascertain whether some of these MAP psychosis subjects have a vulnerability to schizophrenia. Forty-eight patients with MAP psychosis were divided into three groups based on clinical course: transient type, prolonged type and persistent type. Furthermore, the patients with the persistent type were divided into two groups: one group were moderately disturbed in social adaptive functioning and had Global Assessment Functioning scale (GAF) points >50, and the other group consisted of those who were severely disturbed in social adaptive functioning and who had GAF points of < or =50. These MAP patients were tested for exploratory eye movements, which are the vulnerability marker of schizophrenia, and were compared with 30 patients with schizophrenia and 30 healthy control subjects. The responsive search score of the severely disturbed group of patients of the persistent type was lowest, significantly lower than those of the transient type and the healthy controls. It did not differ from that of the schizophrenic subjects. These results suggest that the severely disturbed group of patients with the persistent type of MAP psychosis have a vulnerability to schizophrenia.

Eye movements tell only half the story.

The dramatic improvements of neglect symptoms after prism adaptation (PA) have been interpreted as evidence that PA reorganizes higher levels of spatial representation. Here the authors demonstrate that while the exploratory eye movements of a patient with neglect were clearly shifted toward the left after PA, he still showed no awareness for the left side of the stimuli he was now actively exploring. PA modulates functions of the parietal lobe, such as eye movement control, but fails to influence the underlying mechanisms of neglect.

Exploratory eye movements in schizophrenia

It has been reported that patients with schizophrenia show restricted eye-scanning in comparison with normal controls; however, the precise mechanism underlying the limited eye movement pattern remains unknown. The purpose of this study was to determine the factors affecting restricted eye-scanning in schizophrenic patients by examining exploratory eye movements during demonstration of two different sizes of the S-shaped figure. The second purpose was to determine the effect of the instruction for performance on the restricted viewing pattern in patients with schizophrenia. Eye movements during demonstration of the S-shaped figure of the original or half size were examined in 15 patients with schizophrenia and 15 normal controls using an infrared eye-mark recorder. The patients showed lower search scores than control subjects for both sizes of the figure. The subjects were then instructed to compare a slightly modified figure with the original one. Lower responsive search scores were found for the patients when "fixation point" was defined as a point at which a gaze was held for at least 200 ms, while the patients and control subjects performed equally at the 100-ms setting. Direct instruction to scrutinize the S-shape abolished the difference in the search scores between patients and control subjects at both the 100-ms and 200-ms settings. These findings suggest that the size of the S-figure is not a factor of restricted eye movements, and that the direct instruction improves the visual performance in patients with schizophrenia.

Abnormal exploratory eye movements in schizophrenic patients vs healthy subjects.

We examined previously described exploratory eye movements abnormalities as biologic markers in schizophrenic patients in comparison with age-matched healthy subjects. Using an eye-mark recorder, eye movements were analysed for mean gazing time, total number of gazing points, mean eye scanning length, total eye scanning length, and total gazing times as subjects viewed six simple pictures in preparation for copying them. In-patients, and to a lesser extent, out-patients, with schizophrenia showed a longer gazing time, fewer gazing points, a shorter mean and total eye scanning length. and longer gazing time than healthy subjects. In schizophrenic patients. negative symptom scores were positively correlated with mean gazing time (r = 0.33), and negatively correlated with the total number of gazing points (r = -0.29) as well as, the mean (r = -0.40) and total scanning length (r = -0.46). Exploratory eye movements are a biologic marker useful for evaluation of schizophrenia.

Stability of exploratory eye movements as a marker of schizophrenia — a WHO multi-center study

The exploratory eye movements of patients with schizophrenia reportedly differ from those of patients without schizophrenia and healthy controls. In an attempt to determine whether exploratory eye movements provide valid markers for schizophrenia, the present collaborative study was conducted in six countries to analyze the stability of and variation in the following parameters of exploratory eye movements: the number of eye fixations (NEFs) and mean eye scanning length (MESL) in a retention task; the cognitive search score (CSS) that indicates how frequently the eye focused on each important area of a figure in order to recognize it in a comparison task; and the responsive search score (RSS), which reflects the frequency of eye fixations on each section of a figure in response to questioning in a comparison task. In addition, we investigated the validity of the currently employed discriminant function to extract a common feature of schizophrenia by applying it to the findings of the present study. The exploratory eye movements of 145 patients with schizophrenia, 116 depressed patients and 124 healthy controls at seven WHO collaborative centers in six countries were measured using eye mark recorders during viewing of stationary S-shaped figures in two sequential tasks. The RSSs of patients with schizophrenia were found to be significantly lower than those of depressed patients or healthy controls irrespective of geographical location, with no significant difference existing between the RSSs for depressed patients and those for healthy controls. By inserting the RSS and NEF data for each subject into the formula used to calculate discriminant function, patients with schizophrenia could be discriminated from depressed patients and healthy controls with a sensitivity of 89.0% and a specificity of 86.7%. The RSS is an exploratory eye movement parameter that detected schizophrenia irrespective of culture, race and various other subject variables. Furthermore, it is indicative of the stable, significant difference that exists between subjects with and without schizophrenia. The results of discriminant analysis confirm the previously reported validity of discriminant function.

Compensatory visual field training for patients with hemianopia after stroke

Twenty-one patients with hemianopia received 4 weeks of compensatory visual field training. Detection of and reaction time to visual stimuli were measured with eyes fixating (condition A) and with use of exploratory eye movements (condition B) before and after training. Twenty-three healthy individuals served as control subjects for measurements of parameters during both conditions. Patients with hemianopia to either side showed a marked improvement of detection and reaction time during condition B, but minimum or no change during condition A. Improvements were maintained 8 months after training. Activity of daily living skills also improved in all patients. The size of scotoma on computerized perimetry, in contrast, remained unchanged. Training improved detection of and reaction to visual stimuli without restitution of the visual field defect.

Gender differences of exploratory eye movements: A life span study

Exploratory eye movements of normal subjects (39 male and 39 female) were recorded using an eye-mark recorder. Four parameters mean gazing time, total number of gazing points, mean scanning length, and total scanning length) were analyzed. Subjects were divided into three life spans as prepuberty (boys and girls), adult, and postpuberty. The mean gazing time of adult women was significantly longer than that of age-matched adult men, but not between men and women in prepuberty or postpuberty (postmenopausal older women and age-matched older men). The total number of gazing points of women was significantly smaller than that of men, but not significantly different between men and women in both prepuberty and postpuberty. Both the mean scanning length and total scanning length of adult women were shorter than those of age matched adult men, but no significant differences were found between men and women in both prepuberty and postpuberty. Furthermore, the mean gazing time of adult women was longer than that of men in prepuberty and postpuberty. The total scanning length of adult men was longer than that of women in both prepuberty and postpuberty. These findings suggest that gender differences of exploratory eye movements are observed only during the adult phase, which indicates that visual information processing may be regulated by gonadal hormones in humans.

Gender differences and reproducibility in exploratory eye movements of normal subjects

Exploratory eye movements were recorded using an eye-mark recorder in 48 normal subjects (24 male and 24 female). Gender differences were examined regarding four eye movement parameters such as the mean gazing time, the total number of gazing points, and the mean eye scanning length and the total eye scanning length. The mean gazing time of women was significantly longer than that of men, and the total number of gazing points of women was significantly less than that of men. The mean eye-scanning length of men and women did not differ. The total eye scanning length of men was significantly longer than that of women. Reproducibility between sessions of the four eye movement parameters above was expressed as Pearson correlation coefficients (r) in 24 healthy adults before and after a month interval, yielding respective coefficients of 0.65, 0.42, 0.56 and 0.61. These results suggested that differences in exploratory eye movements between men and women may reflect differences in the characteristics of visual information processing and also confirmed the reproducibility of exploratory eye movement parameters.

Oral presentation: Inhibitory and balancing effects of ATP on the exploratory eye movements in schizophrenic patients

Oral presentation: Inhibitory and balancing effects of ATP on the exploratory eye movements in schizophrenic patients

Exploratory eye movements to pictures in childhood-onset schizophrenia and attention-deficit/hyperactivity disorder (ADHD).

We investigated exploratory eye movements to thematic pictures in schizophrenic, attention-deficit/hyperactivity disorder (ADHD), and normal children. For each picture, children were asked three questions varying in amount of structure. We tested if schizophrenic children would stare or scan extensively and if their scan patterns were differentially affected by the question. Time spent viewing relevant and irrelevant regions, fixation duration (an estimate of processing rate), and distance between fixations (an estimate of breadth of attention) were measured. ADHD children showed a trend toward shorter fixations than normals on the question requiring the most detailed analysis. Schizophrenic children looked at fewer relevant, but not more irrelevant, regions than normals. They showed a tendency to stare more when asked to decide what was happening but not when asked to attend to specific regions. Thus, lower levels of visual attention (e.g., basic control of eye movements) were intact in schizophrenic children. In contrast, they had difficulty with top-down control of selective attention in the service of self-guided behavior.

The activities of the Tokyo Center.

The main World Health Organization (WHO) activities of the Tokyo Center are as follows: (1) It performed the research project entitled 'A Bio-Psycho-Social Study on Children with Emotional and Behavioral Problems' in cooperation with the Beijing and Seoul Centers from 1985 to 1987. These results suggested that the deviant behavior of children in the general population had no biological background, but presumably stemmed from psychosocial disadvantages. (2) It has participated in a field trial for the proposed draft for chapter V of the ICD-10 as the Field Trial Coordinating Center in Japan since 1986 and the first Japanese edition of the ICD-10 Classification of Mental and Behavioral Disorders: Clinical Descriptions and Diagnostic Guidelines were published in 1993. (3) It proposed the collaborative project exploratory eye movements in patients with schizophrenia in 1989 and has promoted the project with the cooperation of six centers that included Beijing, Casablanca, Montreal, Munich, Prague and Sapporo. The findings of the present project indicated that exploratory eye movements may be specific to schizophrenia and can be practically used to discriminate schizophrenia without significantly depending on language.

Disentangling gravitational, environmental, and egocentric reference frames in spatial neglect.

Previous studies in neglect patients using rotation of the body around the roll-axis revealed neglect of visual stimuli not only in the egocentric, body-centered left but also in the environmental left. The latter has been taken as evidence for a gravity-based environment-centered component of neglect occurring independently of the subject's actual body orientation. However, by using visual stimuli in a normally lightened room, the studies confounded the gravitational upright with the visible upright of the surround. Thus, it is possible that the visible upright of the environment may have served the role of the gravitational upright relative to which neglect occurred. The present experiment evaluated the influence of gravity on contralateral neglect when no visual information was presented. In complete darkness, neglect patients' exploratory eye movements were recorded in five experimental conditions: body in normal upright position, body titled 30 degrees to the left and 30 degrees to the right, and body pitched 30 degrees backward and 30 degrees forward. In the upright orientation, the patients with neglect showed a bias of ocular exploration to the ipsilesional right side. In egocentric body coordinates, we found no significant differences between the orientation of the biased search field in the different experimental conditions showing that the search field shifted with the orientation of the body. No significant decrease or enhancement of neglect was observed when body orientation was varied in the different conditions. In conclusion, the present results revealed that the modulation of gravitational forces has no significant influence on the exploratory bias of these patients. When visual information was excluded and only graviceptive information was available, the patients' failure to explore the contralesional part of space appeared purely body-centered. The results argue against a disturbed representation of space in neglect that encodes locations in a gravity-based reference system.

Exploratory eye movement dysfunctions in patients with schizophrenia: possibility as a discriminator for schizophrenia

In our previous studies patients with schizophrenia and their parents had less frequent eye fixations and a more limited area of inspection than normal controls while freely viewing stationary S-shaped figures. The present study attempted to discriminate schizophrenics from non-schizophrenics using exploratory eye movements. Two groups (A and B) were formed, each comprising 30 schizophrenic and 70 non-schizophrenic subjects (10 each of patients with depression, methamphetamine psychosis, alcohol psychosis, anxiety disorder, temporal lobe epilepsy, frontal lobe lesions and healthy normal controls). Discriminant analysis was performed on group A to obtain a discriminant. The validity of applying this discriminant to group B was investigated. By focussing on exploratory eye movements, schizophrenics could be discriminated from non-schizophrenics with a sensitivity of 76.7% and a specificity of 81.4%. These results show that exploratory eye movements are a useful discriminator for schizophrenia.

280 Hormonal influence on exploratory eye movements: analysis of gender difference in healthy subjects and schizophrenic patients

280 Hormonal influence on exploratory eye movements: analysis of gender difference in healthy subjects and schizophrenic patients