Electroencephalographic Microstates in Schizophrenia and Bipolar Disorder

Abstract

Schizophrenia (SCH) and bipolar disorder (BD) are characterized by many types of symptoms, damaged cognitive function, and abnormal brain connections. The microstates are considered to be the cornerstones of the mental states shown in EEG data. In our study, we investigated the use of microstates as biomarkers to distinguish patients with bipolar disorder from those with schizophrenia by analyzing EEG data measured in an eyes-closed resting state. The purpose of this article is to provide an electron directional physiological explanation for the observed brain dysfunction of schizophrenia and bipolar disorder patients.Methods: We used microstate resting EEG data to explore group differences in the duration, coverage, occurrence, and transition probability of 4 microstate maps among 20 SCH patients, 26 BD patients, and 35 healthy controls (HCs).Results: Microstate analysis revealed 4 microstates (A–D) in global clustering across SCH patients, BD patients, and HCs. The samples were chosen to be matched. We found the greater presence of microstate B in BD patients, and the less presence of microstate class A and B, the greater presence of microstate class C, and less presence of D in SCH patients. Besides, a greater frequent switching between microstates A and B and between microstates B and A in BD patients than in SCH patients and HCs and less frequent switching between microstates C and D and between microstates D and C in BD patients compared with SCH patients.Conclusion: We found abnormal features of microstate A, B in BD patients and abnormal features of microstate A, B, C, and D in SCH patients. These features may indicate the potential abnormalities of SCH patients and BD patients in distributing neural resources and influencing opportune transitions between different states of activity.

Abnormalities of EEG Microstates In Drug-Naïve, First-Episode Schizophrenia

“…Our study found increased microstate class C and decreased microstate class D in patients with FE-SCH, which is consistent with some previous studies [19,26,31]. Such abnormalities of microstate class C and D have been identi ed in patients with chronic schizophrenia [21,32], individuals with ultra-high risk for psychosis [33,34], and even siblings of patients with schizophrenia [26]. Two meta-analyses [25,26] published in recent years showed similar results that the occurrence of microstate class C increased and the occurrence of microstate class D decreased in patients with schizophrenia.…”

“…Default mode network is the neural basis of ego [39]; it was found to be activated during internally-oriented mental processes and to play an important role in self-referential thoughts and episodic memory extraction [16,40]. The microstate class C might be generated at the bilateral medial temporal gyrus and the lateral parietal lobe [32], which were found to be associated with self-experience in fMRI studies [41,42]. It was also considered that microstate class C was associated with the activation of the default mode network [16,35], the abnormal activation of which has been repeatedly demonstrated in schizophrenia [43,44].…”

Abnormalities of Electroencephalography Microstates in Drug-Naïve, First-Episode Schizophrenia

“…Our study found increased microstate class C and decreased microstate class D in patients with FE-SCH, which is consistent with some previous studies ( 20 , 29 , 34 ). Such abnormalities of microstate class C and D have been identified in patients with chronic schizophrenia ( 19 , 36 ), individuals with ultra-high risk for psychosis ( 37 , 38 ), and even siblings of patients with schizophrenia ( 29 ). Two meta-analyses ( 28 , 29 ) published in recent years showed similar results that the occurrence of microstate class C increased and the occurrence of microstate class D decreased in patients with schizophrenia.…”

“…Default mode network is the neural basis of ego ( 43 ); it was found to be activated during internally oriented mental processes and to play an important role in self-referential thoughts and episodic memory extraction ( 14 , 44 ). The microstate class C might be generated at the bilateral medial temporal gyrus and the lateral parietal lobe ( 36 ), which were found to be associated with self-experience in fMRI studies ( 45 , 46 ). It was also considered that microstate class C was associated with the activation of the default mode network ( 14 , 39 ), the abnormal activation of which has been repeatedly demonstrated in schizophrenia ( 47 , 48 ).…”

Altered Microstate Dynamics and Spatial Complexity in Late-Life Schizophrenia

“…Microstate syntax analysis found altered microstate transition probabilities in LLS. Several studies have reported the presence of abnormal microstate syntax in patients with schizophrenia; however, the results are somewhat inconsistent (23,33,49). It has been suggested that microstate syntax may represent the sequential activation of distinct brain networks.…”