Dissertation
Dissertation > Medicine, health > Neurology and psychiatry > Psychiatry > Neurosis > Anxiety disorders

Preattentive Processing of Auditory Threatening Stimulus in Patients of Generalized Anxiety Disorder:an Event-related Potential Study

Author WangYaBo
Tutor XuJing
School Dalian Medical University
Course Neurology
Keywords Auditory stimulus Preattentive Mismatch negativityGeneralized anxiety disorder Threatening stimulus Mismatch negativity Event-related potentials
CLC R749.72
Type Master's thesis
Year 2013
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Experiment1Preattentive processing of complex auditory stimulus in healthy adults:a mismatch negativity studyObjective: The mismatch negativity (MMN) is an event-related potentialcomponent that reflects information change detection independent of subjects’ attention.The most of investigators always use tone as standard stimulus, and use changes insound intensity, frequency, time of duration and direction as deviant stimulus to evokeMMN in a long time. In recent years, complex sound (e.g. words) has beendemonstrated to evoke MMN. But there is no study about the complex sound associatedwith daily life (e.g. scream) for MMN. In this study, we use the complex soundassociated with daily life as stimulus to investigate the preattentive automaticprocessing of complex sounds by event-related potentials (ERP), in order to provide anew method to study the dysfunction of preattentive processing of complex auditorystimulus in the lab and clinical researches.Methods: Seventeen healthy subjects (5male/12Female, mean age38.41±9.79years) were selected. The Reverse-oddball paradigm was selected in this study.Stimulus sequence was presented by the E-Prime software, and the stimulus was thecomplex sound associated with daily life. The healthy subjects were required to ignorethe sound delivering over headphones during watching a silent movie. Recorded andanalyzed the electroencephalogram (EEG). Then the mean amplitude of MMN wasanalyzed. Results:1. MMN(neutral sound) vs. zero: there was a significant main effect of group(F(1,32)=4.569, p=0.040).2. MMN(threatening sound) vs. zero: there was a significant main effect ofgroup(F(1,32)=4.637, p=0.039).3. MMN(neutral sound) vs. MMN(threatening sound): there was no significantmain effect of group(F(1,32)=0.015,p=0.904).Conclusion: The complex sound associated with daily life can elicit MMN inpreattentive automatic processing. The sounds can be used to study the preattentiveprocessing for the lab and clinic study. Experiment2Preattentive processing of auditory threatening stimulus inpatients of generalized anxiety disorder:an event-related potential studyObjective: Generalized anxiety disorder (GAD), also known as chronic anxiety, ischaracterized by excessive worry and tension on the day-to-day events or activities. Themechanism of generalized anxiety disorder has not yet been fully clarified. The purposeof this study is to explore the preattentive processing of auditory threatening stimulusamong patients with generalized anxiety disorder.Methods: Sixteen GAD patients (10females and6males, all right-handed, meanage43.44±10.21years) and17age and gender matched healthy volunteers participatedin the current study. The Reverse-oddball paradigm was selected in the study. Allsubjects were required to ignore the sound delivering over headphones during watchinga silent movie. Recorded and analyzed the electroencephalogram (EEG). Then the meanamplitude of MMN was analyzed.Results:1. There was a significant main effect of emotional type(F(1,31)=6.066, p=0.020),and an interaction of Group×emotion type(F(1,31)=6.816, p=0.014). 2. There was a significant main effect of group(F(1,31)=4.867, p=0.035)for MMNevoked by threatening sounds, the amplitudes of the MMN were significantly lower inGAD patients(0.449±0.293μV)than the amplitudes of the MMN in controls(-0.451±0.284μV), while there was no significant main effect of group for MMNevoked by neutral sounds. And also there was a significant main effect of emotionaltype(F(1,31)=12.493, p=0.001)in GAD patients, the amplitudes of MMN evoked bythreatening sounds(0.449±0.293μV)were significantly lower than the amplitudes ofMMN evoked by neutral sounds(-0.743±0.249μV), while there was no significant maineffect of emotional type for healthy volunteers.Conclusion: Patients with generalized anxiety disorder showed dysfunction ofpreattentive processing of auditory threatening stimulus, revealed by reducedpreattentive processing of auditory threatening stimulus.

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