Preattentional Processing Among Patients With Major Depressive Disorder: An Event-related Potential Study

Part 1Mechanism of preattentive processing of physical stimuli in depressive patientsExperiment 1Mechanism of preattentive processing of physical stimuli:An event-related potentials studyObjective:The present study was to investigate the mechanism of preattentive processing of physical stimuli and validate the paradigm revised.Methods:Event-related potential (ERP) was investigated to study preattentive processing of task-irrelevant physical stimuli changes. Fourteen healthy volunteers were recruited for this study. Revised oddball paradigm was used. The subjects were instructed to mentally count the central red targets and ignore the peripheral non-targets. Thirty two channel electroencephalogram (EEG) was recorded by Neuroscan Nuamps System. Mismatch negativity (MMN) was calculated by subtracting the ERPs elicited by the non-target standard stimuli from the non-target deviant stimuli.Results:(1) MMN1:There were a significant main effect of Group (F3,42=9.430, P=0.001); (2) MMN2:There were no significant main effect of Group (F (1,26)=2.891; p=0.101)Conclusion:Revised paradigm can elicite visual MMN indexing preattentive processing of physical stimuli.Experiment 2Mechanism of preattentive processing of physical stimuli in depressive patientsObjective:The present study was to investigate the mechanism of preattentive processing of physical stimuli in depressive patiens.Methods:Event-related potential (ERP) was investigated to study preattentive processing of task-irrelevant physical stimuli changes. Fourteen depressive patients and fourteen healthy volunteers were recruited for this study. Revised oddball paradigm was used. The subjects were instructed to mentally count the central red targets and ignore the peripheral non-targets. Thirty two channel electroencephalogram (EEG) was recorded by Neuroscan Nuamps System. Mismatch negativity (MMN) was calculated by subtracting the ERPs elicited by the non-target standard stimuli from the non-target deviant stimuli.Results:There was no any main effect or interaction of MMN amplitudes.Conclusion:Depressive patients did not show dysfunction of preattentive processing of physical stimuli in oddball paradigm. Experiment 3Mechanism of sensory memory based preattentive processing of physical stimuli in depressive patientsObjective:The present study was to investigate the mechanism of sensory memory based preattentive processing of physical stimuli.Methods:Event-related potential (ERP) was investigated to study preattentive processing of task-irrelevant physical stimuli changes. Fourteen depressive patients and fourteen healthy volunteers were recruited for this study. oddball paradigm and equiprobable paradigm were used. The subjects were instructed to mentally count the central red targets and ignore the peripheral non-targets. Thirty two channel electroencephalogram (EEG) was recorded by Neuroscan Nuamps System. Both oddball-MMN and control-MMN were analyzed.Results:There were a significant main effect of Group (F (1,26)= 6.655, p<0.016) and an interaction of Group×MMN type (F (1,26)= 4.933, p<0.035). Further analysis reveals that there is a significant main effect of group (F (1,26)=9.446, p<0.005) for control-MMN while there is no that for oddball-MMN.Conclusion:Control-MMN decreased significantly in depressive patients. The dysfunction of preattentive processing of physical stimuli in depressive patients was sensory memory based. Part 2Mechanism of preattentive processing of emotional information in depressive patientsExperiment 1Mechanism of preattentive processing of cartoon facial expressions:An event-related potentials studyObjective:The present study was to investigate the mechanism of preattentive processing of facial expressions and whether cartoon facial expressions can elicit mismatch negativity (MMN)Methods:Event-related potential (ERP) was investigated to study preattentive processing of task-irrelevant expressional changes. Fifteen healthy volunteers were recruited for this study. The subjects were instructed to mentally count green faces (targets) and ignore the red ones (non-targets). Thirty two channel electroencephalogram (EEG) was recorded by Neuroscan Nuamps System. MMN was calculated by subtracting the ERPs elicited by the non-target standard stimuli (neutral) from the non-target deviant stimuli (positive or negative)Results:(1) MMN1:There were a significant main effect of Site (F3,42=9.430, P=0.001) and an interaction of Orientation×Hemisphere (F1,14=9.608, P=0.008); (2) MMN2:There were a significant main effect of Orientation(F1,14=5.489, P=0.034) and interactions of Orientation×Type (F1,14=7.369, P=0.017) and Orientation×Hemisphere (F1,14=9.623, P=0.008)Conclusion:Compared with standard neutral faces, infrequent emotional cartoon faces elicited expression-related MMN indexing automatic processing. The MMN amplitude was right-lateralized and larger for negative than positive expression. Experiment 2Mechanism of preattentive processing of facial expressions in depressive patientsObjective:The present study was to investigate the mechanism of preattentive processing of facial expressions in depressive patients.Methods:Event-related potential (ERP) was investigated to study preattentive processing of task-irrelevant expressional changes. Fifteen depressive patients and fifteen healthy volunteers were recruited for this study. The subjects were instructed to mentally count green faces (targets) and ignore the red ones (non-targets). Thirty two channel electro-encephalogram (EEG) was recorded by Neuroscan Nuamps System. Mismatch negativity (MMN) was calculated by subtracting the ERPs elicited by the non-target standard stimuli (neutral) from the non-target deviant stimuli (positive or negative)Results:(1) MMN1:There were a significant interaction of Expression type×Group (F (1,28)=7.052, p<0.015) and a significant interaction of Orientation×Hemisphere (F (1,28)=4.617, p=0.040); (2) MMN2:There were a significant main effect of Group (F (1,28)= 10.804, p<0.005) and interactions of Orientation×Group (F (1,28)= 7.304, p<0.015)Conclusion:Compared with healthy volunteers, depressive patients showed dysfunction of preattentive processing of emotional information. The right-lateralized effect of MMN was absent in depressive patients. Experiment 3Mechanism of preattentive processing of facial expressions in depressive patients using multiple face modelsObjective:To rule out low level process of physical features of the faces, multiple face models were used in this experiment to investigate the mechanism of preattentive processing of emotional information in depressive patients.Methods:Event-related potential (ERP) was investigated to study preattentive processing of task-irrelevant expressional changes. Ten depressive patients and ten healthy volunteers were recruited for this study. The cartoon emotional faces were produced from six different faces. The subjects were instructed to mentally count green faces (targets) and ignore the red ones (non-targets). Thirty two channel electroencephalogram (EEG) was recorded by Neuroscan Nuamps System. Mismatch negativity (MMN) was calculated by subtracting the ERPs elicited by the non-target standard stimuli (neutral) from the non-target deviant stimuli (positive or negative)Results:(1) MMN 1:There were an significant interaction of Group×Hemisphere (F (1,18)=5.698; p=0.028); (2) MMN2:There were a significant main effect of Group (F (1,18)=8.759, p<0.01) and an interaction of Orientation×Type (F(3,54)=3.011; p=0.038)Conclusion:Depressive patients showed dysfunction of preattentive processing of emotional information even when low level process of physical features was ruled out.