The Influence Of Attention On The Discrimination Of Visual Motion Direction In Schizophrenia

Schizophrenia is a serious mental disease and usually cannot live and work normally,which causing huge mental and economic burdens to their families and society.Although the commonly used antipsychotic drugs can effectively improve the clinical symptoms in schizophrenia(such as auditory hallucinations and other positive symptoms),but having little effect on improving cognitive dysfunction(especially motion perception dysfunction).Previous studies showed that visual motion dysfunction in schizophrenia has great clinical value due to its specificity and predictability.The visual motion impairment is manifested by that patients cannot accurately determine the characteristics of object motion,such as speed and direction.For decades,research in motion processing dysfunction mainly focused on whether the dysfunction occurs in the early or late stages of visual information processing.In these studies,the target detection task involving attention(e.g.,the oddball paradigm)was used,but the influence of attention on dysfunction in visual motion processing was not discussed.The present study attempts to explore this influence by answering the following two questions:(1)Whether the attention of patients with schizophrenia is abnormal in the visual motion direction discrimination task;(2)whether attention has influence on the discrimination of visual motion direction(motion related ERP in particular)in schizophrenia patients.Twenty-three schizophrenic patients and twenty-two normal controls with matched IQ,age,and education level participated in two experiments.Behavioral and ERP data were collected from all participants.For schizophrenic patients,extra clinical scale data were collected.In Experiment 1,the classic visual oddball paradigm was used,standard(60%),target(20%),and novel(20%)visual stimuli were created according to the moving direction of gratings,and participants were asked to press a button upon seeing a target stimuli.Based on previous literature,N1 component was used to index early visual moving processing,and P3 a and P3 b were used to respectively index late exogenous and endogenous attention.We found that(1)the schizophrenia had lower sensitivity(d’)and longer reaction time relative to normal group;(2)target and novel stimuli elicited larger N1 than standard stimuli,without group difference(3)In the normal group and the schizophrenia group,the difference in the amplitude of P3 a induced by standard and novel was significant,but the difference was small in the schizophrenia;target stimuli elicited larger P3 b than standard in normal group,but this difference was not significant in the schizophrenia.In Experiment 2,the classic Posner endogenous(an arrow as cues)and exogenous(a flash as cues)attention paradigms were used,and participants were asked to judge the direction of moving gratings.We found that: for both endogenous and exogenous presented cues,(1)relative to invalid cues,valid cues facilitated direction discrimination in both group,but schizophrenic patients responded more slowly;(2)relative to invalid cues,valid cues elicited larger N1,without group difference;(3)N2pc amplitude indexing selective attention was significantly smaller in schizophrenic patients compared to normal group.Conclusions:(1)In the visual motion direction discrimination task,the attention(endogenous and exogenous)of schizophrenia patients is abnormal;(2)There is an influence of attention on the discrimination of visual motion direction(motion related N1 in particular)in schizophrenic patients,and that is comparable to normal people.