Study On The Characteristics Of Eye Trajectory Movement And Its Related Brain Function In Schizophrenia

Objective:A variety of eye movement tasks are proposed to study the eye trajectory movement status in schizophrenia and its related disorders,to explore the characteristics of eye trajectory movement in schizophrenia and to investigate its relationship with resting state brain functional activity.Methods:（1）Eye movement data were collected from 80 patients with first-episode schizophrenia,32 patients with chronic schizophrenia,51 cases of prodromal syndrome,38 relatives of schizophrenia,and 96healthy controls under free-viewing,smooth pursuit,and fixation stability tasks,and the subjects’clinical symptoms were assessed by PANSS,SOPS,and HADS scales,and non-parametric tests were used to compare the differences of eye movements in different disease states,and the eye movement indexes were correlated with the total scores of symptom scales.（2）Eye movement data of 97 patients with affective disorders（including 39 cases of monophasic depression,24 cases of bipolar depression and 34 cases of bipolar mania）,93 patients with schizophrenia and 93 healthy controls were collected,and the clinical symptoms of the subjects were evaluated by YMRS,HAMD and HADS scales.（3）Resting-state functional MRI data and eye movement data were collected from 27 first-episode schizophrenia patients,25 cases of prodromal syndrome and 29 healthy controls,and the clinical symptoms of the subjects were assessed by PANSS,SOPS,and HADS scales,and correlation analysis was used to explore the relationship between eye movement abnormalities and regional homogeneity of different brain regions in individuals with schizophrenia and prodromal syndrome.Results:（1）Patients with schizophrenia had extensive eye movement abnormalities in multiple eye movement tasks:in the free-viewing task,patients with schizophrenia adopted an inefficient information acquisition pattern,mainly manifested by a decrease in the number of fixations,a prolonged mean duration of fixations,a decrease in the number of saccades,a decrease in saccadic amplitude,a decrease in average and peak saccadic velocity,a shortening of scanpath,and a decrease in dispersion（all,P<0.05）.These eye movement abnormalities were already present in subjects with prodromal syndrome,were not significantly different in first-episode and chronic patients,and were not related to disease severity(P_Bonferroni>0.05);in the smooth pursuit tasks,patients with schizophrenia showed increased saccadic duration,saccadic amplitude,and peak saccadic velocity on several tracking tests（all,P<0.001）,decreased gain（P<0.05）,with some eye movement abnormalities already present in subjects with prodromal syndrome and no significant differences between first-episode and chronic patients,where root-mean-square error of position in HS4B,LS2 and LS2B tasks were positively correlated with PANSS(P_Bonferroni<0.05);in the fixation stability tasks,schizophrenic patients showed an increase in saccade duration,amplitude and scanpath in both interference and non-interference modes（P<0.001）,and partial abnormalities in eye movement indexes were also present in prodromal syndrome,with no significant difference between first-episode and chronic schizophrenia;the number of fixations,number of saccades,and saccadic amplitude were positively correlated with total PANSS scores in interference mode,and the mean fixation duration was negatively correlated with total PANSS scores(all,P_Bonferroni<0.05).（2）Patients with affective disorders had extensive eye movement abnormalities in multiple eye movement tasks:in the free-viewing task,patients with affective disorders adopted an inefficient information acquisition pattern,mainly showing decreased saccadic amplitude,decreased average saccadic velocity,shortened scanpath,and decreased disperson（all,P<0.05）;in the smooth pursuit tasks,patients with affective disorders showed an increase in saccadic duration in all tests（all,P<0.05）except HS4,and eye movement abnormalities were particularly significant in the smooth pursuit tasks with complex backgrounds（HS4B and LS2B）;in the fixation stability tasks,patients with affective disorders had significant eye movement abnormalities in both interference and non-interference modes,showing an increase in the number of fixations and saccades,a decrease in fixation duration,and an increase in saccadic duration,amplitude,and scanpath（all,P<0.01）.The trend of abnormal eye movements in affective disorders was similar to that in schizophrenic patients and was between healthy controls and schizophrenic patients;similar eye movement characteristics were shown in different onset states of affective disorders(all,P_Bonferroni>0.05).Using a fully connected neural network model,severe mental illness could be distinguished using only eye movement data:the classification accuracy between patients with schizophrenia and healthy controls was 0.948;the classification accuracy between patients with affective disorders and healthy controls was 0.848;the classification accuracy between patients with schizophrenia and non-schizophrenia was0.842.（3）Functional activity in the superior temporal gyrus in healthy controls was correlated with the number of fixations（R=0.433,P=0.03）and the number of saccades（R=0.411,P=0.041）in the free-viewing task,gain（R=0.433,P=0.031）in the HS4B smooth pursuit task,saccade duration（R=0.414,P=0.040）in HS4X smooth pursuit task,and horizontal position difference（R=-0.400,P=0.047）in LS4 smooth pursuit task,but no significant correlations were found in patients with schizophrenia.Conclusion:（1）Patients with schizophrenia have extensive eye movement abnormalities in multiple eye movement tasks,free-viewing eye movement abnormalities may be characteristic indicators of schizophrenia,and eye movement abnormalities under smooth pursuit and fixation stability tasks may be state indicators of the disease.（2）Patients with affective disorders also have eye movement abnormalities similar to those in schizophrenia,but between schizophrenia and healthy controls,and eye movement performance in patients with affective disorders is not related to disease type or onset status.（3）Eye movement features can be used as biomarkers for early screening of schizophrenia,and the combination of eye movement features under multitasking can improve the classification accuracy.（4）Abnormal temporal brain functional activity may be related to free-viewing and smooth pursuit eye movement dysfunction in patients with schizophrenia.