Astudy Of The Neural Mechanism Of The Effect Of Negative Emotional Bias On Cognitive Function In Patients With Post-stroke Depression

Background and ObjectivePost-stroke depression(PSD)seriously affects stroke patients’ daily life and neurological function recovery.It is of great significance to explore the neural mechanism of PSD for the early identification and diagnosis of PSD.Various studies have shown that the human brain is more sensitive to negative emotional stimuli.Research on negative emotional bias in patients with primary depression has achieved fruitful results.However,the related mechanism of negative emotional bias in PSD with similar clinical manifestations and physiological basis is unclear.In this study,we combined behavioural and electrophysiological indicators to examine the effect of negative emotional bias on cognitive function in healthy subjects.Then the paradigm was applied to PSD patients to explore the effect of negative emotional bias on their cognitive function and its neural mechanism.MethodsTwenty-two healthy young adults and 21 healthy middle-aged adults were enrolled in experiment 1.Seventeen PSD patients,16 post-stroke non-depression(PSND)patients and 17 healthy controls(HCs)were enrolled in experiment 2.The modified oddball paradigm was adopted in this study,in which auditory stimulus materials consisted of 80%standard stimulus(1000 Hz)and 20%deviant stimulus(2000 Hz)pure tone.The main change of this paradigm was to add neutral and fearful face images selected from the Chinese Facial Expression Picture System(CFAPS)as visually emotional perception materials.Faces with dashed lines in the outer frame were the target stimuli.Each trial started with one facial expression(neutral or fearful)picture,and at 200 ms after picture onset,a tone(standard or high-deviant)was presented.The subjects were asked to ignore the auditory stimulus and perform a rapid keystroke response when they saw the target stimulus.Before the experiment,the Montreal Cognitive Assessment Beijing version(MoCA),patient Health questionnaire-9 items(PHQ-9)and Hamilton Depression scale-24 items(HAMD-24)were assessed.During the experiment,the behavioural data of subjects’ response time(RT)and accuracy(ACC)and their Electroencephalograph(EEG)data were collected.N100(N1)and Mismatch negativity(MMN)components reflecting early perceptual processing and P300(P3)components reflecting late cognitive processing were measured.The differences between these behavioural data and components under two kinds of emotional faces were compared,and the effect of negative emotional bias on the subjects’ cognitive function was analyzed.ResultsExperiment 1 Our results showed that the N1 amplitude induced by standard stimuli was smaller than deviant stimuli in healthy subjects.The N1 amplitude induced by the standard stimulus was smaller under the fearful faces than under the neutral faces.The MMN amplitude under fearful faces was more negative than under neutral faces.Experiment 2 On the depression symptom scales,the scores of PHQ-9 and HAMD-24 in the PSD group were significantly higher than those in the PSND group and HC group.The average score of MoCA in the HC group was significantly higher than that in the PSND group.At the same time,there was no significant difference in the average score between the PSD group and the PSND group.In the behavioural data,the PSD group was slower than the PSND group and HC group,and the PSD group was significantly slower than the PSND group.In addition the PSD group had lower accuracy than the HC group.The ERP result showed that the MAN amplitude of the PSD group under the fearful expressions was smaller than that under the neutral expressions.Both PSND and HC groups showed that the amplitude of P3 under the fearful expressions was significantly smaller than that under the neutral expressions.In contrast,the PSD group showed the opposite result The peak amplitude of P3 under the fearful expressions was larger than that under the neutral expressions.Conclusions(1)In healthy subjects,negative emotion promotes feature extraction and pattern detection of auditory stimuli.It enhances the ability of auditory change detection,suggesting that negative emotion tends to promote the early perceptual processing stage of information.(2)In healthy subjects,the early ageing stage mainly affects the perceptual processing stage of information processing.Middle-aged adults can achieve the same performance as young adults in the later stage of cognitive processing by successfully inhibiting the negative emotional bias unrelated to the task.(3)The effect of negative emotion on early perceptual processing ability was not obvious in PSD patients,and they were still unable to successfully suppress the effect of task-independent emotional bias in the late stage of cognitive processing.