| ?The International Classification of Sleep Disorders?defines chronic insomnia as the inability to get enough sleep despite creating opportunities for adequate sleep;This happened at least three nights a week for three months,and the daytime had a negative effect.It may be characterized by difficulty starting or maintaining sleep,accompanied by significant distress and daytime dysfunction(including fatigue,cognitive decline,mood disorders,inattention,poor quality of life,etc.),with approximately one-third of the population suffering from insomnia symptoms and approximately 10%meeting the criteria for a sleep disorder.In recent years,the prevalence of insomnia is increasing year by year,which affects the physical and mental health of a large part of the population.Chronic insomnia is not only associated with a reduced quality of life and reduced productivity at work and school,it also increases the incidence of mental illness,accidental injury,and occupation of medical resources,which are associated with significant direct and indirect costs.Treatment seeking in patients with insomnia is typically prompted by impairment of daytime function,with the most common factors being fatigue,impaired work performance,cognitive complaints,emotional disturbance,and social/relationship dysfunction.Preliminary work from our group reveals that impairment in social interactions and emotion regulation are salient concerns for those with insomnia.But there has been relatively little investigation of the direct socioemotional impact of insomnia.Cognitive psychology holds that cognitive activity is a process in which the body receives the input of external signals and processes the input information,including psychological activities such as perception,attention,memory and thinking.Emotional processing is a high-level cognitive process that plays an important role in interpersonal communication.Accurate and comprehensive perception of emotional information is crucial for effective social communication.Cognitive impairment can slow down the speed at which information is processed.Therefore,it is also crucial to observing information processing speed when assessing cognitive function.Most of the information we get from our surroundings is acquired visually.Faces are undoubtedly the most important stimuli in social interactions,and facial expressions are one of the most important types of signals.Facial expressions are essential for effective social interaction.Recognizing facial expressions makes it possible to understand other people's emotional states,communicate intentions,and trigger appropriate behavior.Consistent with this adaptive function,the ability to accurately recognize facial expressions has positive effects on functional outcomes,such as social adaptation and mental health.Therefore,facial expression recognition is one of the most important ways of emotional communication.Recognition of facial emotional response and regulation of emotional state are of great significance to people.People with impaired emotional recognition,such as those with autism spectrum disorders and schizophrenia,show difficulty in this area.Recognition of happy faces helps to cooperate with and influence others in social interactions,A consistent evidence that positive(happy)facial expressions than negative facial expressions(sadness,anger and disgust)recognition much faster,this is a positive advantage of classification(PCA).It should be noted that the PCA's task of simple two-choice classification actually reflects a unique mechanism that emerges from recognition/classification and memory of facial expressions in most previous studies.PCA may reflect a higher level of asymmetry in identifying and classifying positive and negative emotional signals.Event-related potential(ERP)is a simple,reliable,high-time-resolution,non-invasive neuroelectrophysiological examination,which can reflect the potential brain activity and neuroelectrophysiological changes in the cognitive process.At present,it has been widely used in practice as a recognized assessment method that can relatively objectively reflect the cognitive function.PCA mainly occurs in the pre-exercise muscle processing stage.N170,an early primitive component of ERP,is a negative wave that occurs between 140 and 180 milliseconds after the onset of occipito-temporal electrode stimulation and has a specific sensitivity to facial expressions.N170 can be modulated by facial emotions,with happy faces evoking a smaller amplitude than other emotions.P3 is the general term for a series of relatively late positive components distributed along the centro-parietal or centro-frontal midline.P3 was originally found in the experimental paradigm of responding to task-related infrequent stimuli,and was found to be highly sensitive to the subjective probability of the occurrence of the evoked event.To date,convergence evidence suggests that the titer level of emotional faces can modulate P3 when the level of stimulus is controlled.In particular,when the picture was associated with a task,such as a valence assessment to ensure that participants paid attention to the picture,the P3 amplitude induced by pleasant faces was larger than that induced by unpleasant faces.Compared with the results of the traditional cognitive psychological scale,ERP examination can be used as a sensitive electrophysiological index for early diagnosis and monitoring the course of disease.To our knowledge,no studies have directly examined PCA in insomnia patients.In this study,happy,neutral and sad cartoon faces were used as expression stimuli to investigate the Accuracy(ACC)and Reaction Time(RT)of chronic insomnia patients in classifying the three expressions.In order to further explore the cognitive processing mechanism of facial expression classification,the temporal characteristics(ERP related components)of facial expression classification were analyzed.This research further clarifies the process of emotional information processing by patients with insomnia.Chapter ?Behavioral changes in facial expression classification in patients with chronic insomniaObjective:The empirical analysis showed that the classification speed of positive facial expressions was significantly faster than that of negative facial expressions(PCA).In this study,for the first time,we investigated whether PCA exists in patients with chronic insomnia from the aspect of behavioral science.Methods:This experiment included 30 chronic insomnia patients and 30 healthy volunteers of matching age and education level.And a week before completing the facial task,all study participants completed a seven-day sleep diary to assess the continuity and quality of sleep and to help rule out circadian rhythm problems.All subjects underwent a full night of polysomnography(PSG)monitoring and assessment.Subjects were asked to go to bed before 10:00 pm and wake up at 6:00 am the next day to record the following sleep parameters:Sleep onset latency(SOL),Wake time after Sleep onset(WASO),Total Sleep time(TST),time in bed(TIB),Sleep efficiency(SE),Apnea hypopnea index(AHI)and Periodic limb movements of sleep arousal index(PLMS).On the second day after PSG monitoring,all the volunteers with more than 6 hours of sleep and the subjects with insomnia were subjected to a behavioral experiment of facial expression classification in an independent,quiet room from 10:00 am to 11:00 am.The Pittsburgh Sleep Quality Index(PSQI),Insomnia Severity Index(ISI),Self-Rating Depression Scale(SDS),Self-rating Anxiety Scale(SAS),Minimum Mental State Examination(MMSE)and Montreal Cognitive Assessment(MOCA)were evaluated.Statistical analysis was performed using SPSS 22.0 software(Chicago,IL,USA).Results:There was no significant difference in the percentage of correct answers to the categories of happy and sad expressions between the insomnia patients(95.47±4.94%)and the control group(97.03±2.93%).The control group responded faster to happy faces(606.72±83.68ms)than to sad faces(641.56±69.99ms).However,compared with the control group,patients showed a slower response time(673.27±87.30ms)compared with the control group(624.14±78.47ms).There was no significant difference in the response time to happy expressions(665.48±97.54ms)and to sad expressions(681.05±76.59ms).Conclusion:Although accuracy was similar between the two groups,we found significant differences in response time between the groups.In the normal control group,happy expressions were classified more quickly than sad ones(i.e.PCA).Compared with the control group,the insomnia patients were slower to recognize emotional expressions,and the recognition speed of happy expressions slowed down more significantly,and PCA disappeared.These data suggest that there are obstacles in the classification of facial expressions in patients with insomnia and it also reveals an important link between insomnia and emotional processing..Chapter 2Study on Event Related Potential Classification of Facial Expression in Patients with Chronic InsomniaObjectives:In view of the fact that we have observed that patients with chronic insomnia have facial expression classification disorders using behavioral experiments.In order to explore the cognitive processing mechanism of classification,further measurement of event-related potential is needed.In this study,we used facial expression categorization paradigm and event-related potential to measure the categorization bias of happy faces,neutral faces and sad faces.Methods:This experiment included 23 chronic insomnia patients and 22 healthy volunteers with matching age and education level.And a week before completing the facial task,all study participants completed a seven-day sleep diary to assess the continuity and quality of sleep and to help rule out circadian rhythm problems.All subjects underwent a full night of polysomnography(PSG)monitoring and assessment.Subjects were asked to go to bed before 10:00 pm and wake up at 6:00 am the next day to record the following sleep parameters:Sleep onset latency(SOL),Wake time after Sleep onset(WASO),Total Sleep time(TST),time in bed(TIB),Sleep efficiency(SE),Apnea hypopnea index(AHI)and Periodic limb movements of sleep arousal index(PLMS).On the second day after PSG monitoring,all the volunteers with more than 6 hours of sleep and the subjects with insomnia were subjected to the event-related potential test of facial expression classification in an independent,quiet room from 10:00am to 11:00am.The Pittsburgh Sleep Quality Index(PSQI),Insomnia Severity Index(ISI),Self-Rating Depression Scale(SDS),Self-rating Anxiety Scale(SAS),Minimum Mental State Examination(MMSE)and Montreal Cognitive Assessment(MOCA)were evaluated.Statistical analysis was performed using SPSS 22.0 software(Chicago,IL,USA).Results:N170 and P3 components were derived from the three emotional faces of two groups of subjects.The normal group recorded a greater N170 amplitude in the right hemisphere;The maximum amplitude is at the P7/P8 electrode.Compared with neutral and happy expressions,sad expressions induced the largest N170 amplitude.For the N170 incubation period,the right hemisphere was observed to have a shorter incubation period than the left hemisphere.There was no significant difference in the above indexes between the insomnia group and the normal control group.In the normal group,the amplitude of P3 recorded at CZ and PZ electrodes was higher than that of FZ electrodes,and the amplitude induced by sad faces was significantly lower than that of happy faces and neutral faces.In terms of the performance of the latency period,the PZ electrode position has the shortest latency period.The amplitude of P3 recorded in the chronic insomnia group was significantly lower than that in the control group,and there was no significant difference in the amplitude induced by the three expressions.The incubation period of P3 in chronic insomnia group was not significantly different from that of normal control group.The results of correlation analysis indicated that the amplitude of P3 was negatively correlated with the reaction time(RT).Conclusion:There is no significant abnormality in the basic processing function of facial expression classification in the time range of N170 in patients with chronic insomnia,indicating that the visual processing of basic facial information in patients with insomnia is complete.However,in the insomnia group,the P3 amplitude induced by happy,neutral and sad expressions was significantly reduced,suggesting that insomnia patients may have a deficiency in the advanced cognitive processing ability of facial expression classification.This finding also provides support for the overall long RTS of insomnia patients. |
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