Detection of cognitive impairment in patients with obstructive sleep apnea hypopnea syndrome using mismatch negativity

In this experiment, 97 patients with obstructive sleep apnea hypopnea syndrome were divided into three groups （mild, moderate, severe） according to minimum oxygen saturation, and 35 healthy subjects were examined as controls. Cognitive function was determined using the mismatch negativity paradigm and the Montreal Cognitive Assessment. The results revealed that as the disease worsened, the mismatch negativity latency was gradually extended, and the amplitude gradually declined in patients with obstructive sleep apnea hypopnea syndrome. Importantly, mismatch negativity latency in severe patients with a persistent time of minimum oxygen saturation 〈 60 seconds was significantly shorter than that with a persistent time of minimum oxygen saturation 〉 60 seconds. Correlation analysis revealed a negative correlation between minimum oxygen saturation latency and Montreal Cognitive Assessment scores. These findings indicate that intermittent night-time hypoxemia affects mismatch negativity waveforms and Montrea Cognitive Assessment scores. As indicators for detecting the cognitive functional status of obstructive sleep apnea hypopnea syndrome patients, the sensitivity of mismatch negativity is 82.93%, the specificity is 73.33%, the accuracy rate is 81.52%, the positive predictive value is 85.00%, the negative predictive value is 70.21%, the positive likelihood ratio is 3, and the negative likelihood ratio is 0.23. These results indicate that mismatch negativity can be used as an effective tool for diagnosis of cognitive dysfunction in obstructive sleep apnea hypopnea syndrome patients.

Effect of escitalopram on cognitive function in depressionA mismatch negativity potentials study

We detected the event-related potential mismatch negativity （MMN） of 30 depression patients and compared to 30 age,gender,and education-matched healthy controls.Results showed that amplitudes of frequency and duration MMN were lower in depression patients compared with control patients,indicating abnormality in auditory processing （i.e.,cognitive impairment）.Following escitalopram treatment for 8 weeks,the amplitudes of frequency and duration MMN were significantly increased and Hamilton Rating Scale for Depression scores were significantly decreased in depression patients.These data suggest that escitalopram can improve cognitive function of patients with depression.Further,MMN may be a useful tool for evaluating cognitive function and treatment effects.

Spatial Properties of Mismatch Negativity in Patients with Disorders of Consciousness

In recent decades, event-related potentials have been used for the clinical electrophysiological assessment of patients with disorders of consciousness （DOCs）. In this paper, an oddball paradigm with two types of frequencydeviant stimulus （standard stimuli were pure tones of 1000 Hz; small deviant stimuli were pure tones of 1050 Hz; large deviant stimuli were pure tones of 1200 Hz） was applied to elicit mismatch negativity （MMN） in 30 patients with DOCs diagnosed using the JFK Coma Recovery Scale- Revised （CRS-R）. The results showed that the peak amplitudes of MMN elicited by both large and small deviant stimuli were significantly different from baseline. In terms of the spatial properties of MMN, a significant interaction effect between conditions （small and large deviant stimuli） and electrode nodes was centered at the frontocentral area. Furthermore, correlation coefficients were calculated between MMN amplitudes and CRS-R scores for each electrode among all participants to generate topographic maps. Meanwhile, a significant negative correlation between the MMN amplitudes elicited by large deviant stimuli and the CRS-R scores was also found at the frontocentral area. In consequence, our results combine the above spatial properties of MMN in patients with DOCs, and provide a more precise location （frontocentral area） at which to evaluate the correlation between clinical electrophysiological assessment and the level of consciousness.

Characterization of event-related potentials in obsessive compulsive disorder patients: Comparison with depression and generalized anxiety disorder patients

BACKGROUND： Study results of event-refated potential in obsessive compulsive disorder （OCD） remain controversial, potentially as a result of different instruments utilized and their differing technical characteristics. OBJECTIVE： To investigate the differences in several common event-related potentials, Le. contingent negative variations, P300, and mismatch negativity （MMN）, in OCD patients, depression patients, generalized anxiety disorder （GAD） patients, and healthy controls. DESIGN, TIME AND SETTING： A case-control study was performed in the Department of Electrophysiology, Shanghai Mental Health Center from May 2002 to December 2005. PARTICIPANTS： A total of 38 OCD patients, 20 depression patients, and 18 GAD patients, who were diagnosed according to the criteria of Chinese Classification of Mental Disorders （Version 3）, formulated by the Chinese Psychiatry Association, were selected from the Outpatient Department of Shanghai Mental Health Center. Patients with two or more the above diseases were excluded. In addition, 28 healthy people, gender and age matched, were selected as controls. METHODS： Contingent negative variations, P300, and MMN were recorded by a Nicolet Spirit Instrument. All electrodes were attached at Cz according to the Intemationa11020 system, with the mastoid leads as reference and Fpz as ground. MAIN OUTCOME MEASURES： Amplitude and latency of contingent negative variations, P300, and MMN. RESULTS： The contingent negative variations, P300, and MMN were different （P 〈 0.01）. OCD patients showed an increased MI amplitude compared with controls, depression, and GAD patients （P 〈 0.01）. Target P300 amplitudes were significantly lower in OCD, depression, and GAD patients compared with controls （P 〈 0.01）. Moreover, N2 latency and latency of MMN were prolonged in OCD and depression groups compared with controls （P 〈 0.05）. CONCLUSION： Event-related potentials were different in depression, GAD, and OCD patients and healthy controls. In particular, OCD patients exhibited unique characteristics.

Effects of Repetitive Transcranial Magnetic Stimulation Treatment on Event-Related Potentials in Schizophrenia

Background：Repetitive transcranial magnetic stimulation （rTMS） and event-related potentials （ERPs） are a noninvasive technique that widely used in neurophysiological field.Although rTMS has shown clinical utility for a number of neurological conditions,Recently,there was little understanding of the the efficacy ofrYMS on Schizophrenia（SZ） and the change of ERP between before and after rTMS treatment.The objective of this study was to investigate the characteristics of N400,mismatch negativity （MMN）,and P300 before and after treatment with rTMS in SZ.Methods：One hundred and twenty-seven SZ patients hospitalized in Shanghai Mental Health Center from March 2015 to July 2017,divided into two groups （85 patients were recruited as rTMS group and 42 were recruited as sham rTMS [ShrTMS] group） and 76 normal controls （NCs） who were the staff and refresher staff in our hospital were recruited at the same time.A Chinese-made rTMS and a Runjie W J-1 ERPs instrument were used in the present experiment.N400 was elicited by congruent and noncongruent Chinese idioms.After rTMS treatment,N400,P300,and MMN characteristics were compared with those before treatment and NC group.Results：Compared with NC,the SZ patients exhibited delays in N400,P300,and MMN latency and decreased N400,P300,and MMN amplitudes in their frontal area （P 〈 0.05）.After 25 rTMS treatments,N400 amplitudes in the frontal area （elicited by idioms with same phonic and different shape and meaning and with different phonic,shape,and meaning） were increased in the SZ patients （P 〈 0.05）.However,there was no significant change in N400 before and after treatment with ShrTMS in SZ patients （P 〉 0.05）.Amplitudes for MMN and target P300 also increased in SZ patients after rTMS treatment （P 〈 0.05）.Conclusions：Based on our preliminary findings,we believe that the combined usage of N400,MMN,and P300 could be a valuable index and an electrophysiological reference in evaluating the effects ofrTMS treatment in SZ patients.

Auditory pre-attentive processing of Chinese tones

Background Chinese tones are considered important in Chinese discrimination. However, the relevant reports on auditory central mechanisms concerning Chinese tones are limited. In this study, mismatch negativity （MMN）, one of the event related potentials （ERP）, was used to investigate pre-attentive processing of Chinese tones, and the differences between the function of oddball MMN and that of control MMN are discussed. Methods Ten subjects （six men and four women） with normal hearing participated in the study. A sequence was presented to these subjects through a loudspeaker, the sequence included four blocks, a control block and three oddball blocks. The control block was made up of five components （one pure tone and four Chinese tones） with equiprobability. The oddball blocks were made up of two components, one was a standard stimulus （tone 1） and the other was a deviant stimulus （tone 2 or tone 3 or tone 4）. Electroencephalogram （EEG） data were recorded when the sequence was presented and MMNs were obtained from the analysis of the EEG data. Results Two kinds of MMNs were obtained, oddball MMN and control MMN. Oddball MMN was obtained by subtracting the ERP elicited by standard stimulation （tone 1） from that elicited by deviant stimulation （tone 2 or tone 3 or tone 4） in the oddball block; control MMN was obtained by subtracting the ERP elicited by the tone in control block, which was the same tone as the deviant stimulation in the oddball block, from the ERP elicited by deviant stimulation （tone 2 or tone 3 or tone 4） in the oddball block. There were two negative waves in oddball MMN, one appeared around 150 ms （oddball MMN 1）, the other around 300 ms （oddball MMN 2）. Only one negative wave appeared around 300 ms in control MMN, which was corresponding to the oddball MMN 2. We performed the statistical analyses in each paradigm for latencies and amplitudes for oddball MMN 2 in discriminating the three Chinese tones and reported no significant differences. But the latencies and amplitudes for control MMN in discriminating the three tones all were significantly different. Conclusions There are evident waveforms for oddball and control MMN obtained in normal hearing persons, indicating that the change of Chinese tones could be detected in the pre-attentive stage. Because control MMN can eliminate reflects for physical characteristics of sound, it is the genuine memory-based pre-attentive processing. Since control MMN can reflect the differences of Chinese tones processing better than oddball MMN, it is more sensitive in evaluating pre-attentive processing in Chinese tones discrimination.