A Mismatch Negativity Study Of Visual Physical Stimulus In Patients Of Panic Disorder As Measured By A Multi-feature Paradigm

Experiment 1 A mismatch negativity study of visual physical stimulus by a multi-feature paradigmObjective : The mismatch negativity (MMN) is an event-related potential component that reflects information change detection independent of subject's attention. In the past,oddball paradigm is used to study MMN, which consume the long time and only one deviation could be detected in one block. N??t?nen optimized the traditionary oddball paradigm, which used to study MMN , and designed the auditory optimal paradigm by which could appear multi-feature physical stimulus in one block. It is applied to clinic research because of its time-effective. There is no study about optimal paradigm for visual channel. In this study , we will probe whether the optimal paradigm is suitable for the visual channel which may provid a new paradigm to study the dysfunction of pre-attention processing of visual channel in the lab and clinic research.Methods: 33 healthy volunteers was divided into 16 for the Optimal₁ group and 17 for the Optimal₂ group with age- and sex- matched. The standard stimulus is blue rectangle, deviant stimulus are color, size, shape and direction. For Optimal₁ group , every other stimulus was a standard (P=0.5) and every other was one of the 4 deviants. And for Optimal₂ group, all the 4 types of deviants were presented in the same sequence but with 3 standards (p=0.75) between each successive 2 deviants. A 64 channel electroencephalogram was recorded. After off-line analysis , the mean amplitudes elicited by the deviant in occipital and temporal regions were for statistics . One-tailed t tests were conducted to determine whether the MMN mean amplitudes significantly differed from zero. The two sub-components were analyzed using repeated measures analyses of variance (RMANOVAs).Results1. In Optimal₁ group, the mean amplitudes of the two sub-components of MMN elicited by size and direction deviants significantly differed from zero(t=-2.31^-4.13,p<0.05). In Optimal₂ group, the mean amplitudes of the two sub-component of MMN elicited by all the four deviants were significantly differed from zero(t=-2.33^-8.04, p<0.05).2. There is group main effect in the two groups, the mean amplitudes of Optimal₂ group is larger than that of Optimal₁ group. Early VMMN(F(1,31)=4.698,p<0.05)and late VMMN(F(1,31)=8.187,p<0.05)both have significantly difference.Conclusion1. There is MMN in the visual channel.2. The Optimal paradigm which can elicited robust VMMNs , can be used to research the dysfunction of pre-attention processing of visual channel for the lab and clinic work.Experiment 2A mismatch negativity study of visual physical stimulus in patients of panic disorder as measured by a multi-feature paradigmObjective:Panic disorder (PD) is a common mental disorder characterized by recurrent, sudden and unexpected panic attacks. It is often disabling, especially complicated by agoraphobia, and that affected substantial functional morbidity and reduced the quality of life. The mechanism of PD has not yet been fully clarified. Beck and Clark's theory support that the abnormal automatic information processing is dominant in the mode. But there was lack of forceful evidence. The mismatch negativity (MMN) is an event-related potential component that reflects information change detection independent of subject's attention. But to date, there is only one auditory MMN rather than visual channel research applied to patient with panic disorder. In our study, we use the paradigm as mentioned in Experiment 1 to probe if the panic disorder patients have damage in the pre-attention of visual physical stimulus and measure the further specificity of the disease.Method: 15 patients with PD and 15 age- and sex- matched healthy volunteers were involved in the study and Optimal₂ paradigm was adopted . For each type of deviant choose the time windows according to the group average waveform. And others were as same as Experiment 1.Result1. There is no main effect or interaction between the group for the amplitude. Both of the two sub-components of have main effects of encephalic region distribution. The early VMMN(F(2,27)=10.583,p<0.05)and the late VMMN(F(2,56)=10.673,p<0.05)are both strengthened in the occipital region.2.There is no main effect between group the latency of MMN.Conclusion1. We didn't find any dysfunctions of pre-attention processing of visual physical stimulus in PD patients.2. There may be exhibit the channel specificity in PD patients.