Abstract
Dysfunctional processing of auditory sensory gating has generally been found in schizophrenic patients and ultra-high-risk (UHR) individuals. The aim of the study was to investigate the differences of functional interaction between brain regions and performance during the P50 sensory gating in UHR group compared with those in first-episode schizophrenia patients (FESZ) and healthy controls (HC) groups. The study included 128-channel scalp Electroencephalogram (EEG) recordings during the P50 auditory paradigm for 35 unmedicated FESZ, 30 drug-free UHR, and 40 HC. Cortical sources of scalp electrical activity were recomputed using exact low-resolution electromagnetic tomography (eLORETA), and functional brain networks were built at the source level and compared between the groups (FESZ, UHR, HC). A classifier using decision tree was designed for differentiating the three groups, which uses demographic characteristics, MATRICS Consensus Cognitive Battery parameters, behavioral features in P50 paradigm, and the measures of functional brain networks based on graph theory during P50 sensory gating. The results showed that very few brain connectivities were significantly different between FESZ and UHR groups during P50 sensory gating, and that a large number of brain connectivities were significantly different between FESZ and HC groups and between UHR and HC groups. Furthermore, the FESZ group had a stronger connection in the right superior frontal gyrus and right insula than the HC group. And the UHR group had an enhanced connection in the paracentral lobule and the middle temporal gyrus compared with the HC group. Moreover, comparison of classification analysis results showed that brain network metrics during P50 sensory gating can improve the accuracy of the classification for FESZ, UHR and HC groups. Our findings provide insight into the mechanisms of P50 suppression in schizophrenia and could potentially improve the performance of early identification and diagnosis of schizophrenia for the earliest intervention.
Highlights
Sensory gating, defined as the ability of the brain to separate important from irrelevant sensory stimuli, is one of the early stages of information processing and cognition (Hall et al, 2010)
On the contrary, speed of processing, verbal learning, working memory, and the overall composite index were revealed by post hoc tests to be significantly poorer in first-episode schizophrenia patients (FESZ) compared with healthy controls (HC), whereas ultra-high risk individuals (UHR) did not significantly differ from either FESZ or HC
The results of this study indicate that brain functional network based on EEG of P50 paradigm may be helpful for the identification of different stages (FESZ, UHR, HC) of schizophrenia and assist early diagnosis of schizophrenia
Summary
Sensory gating, defined as the ability of the brain to separate important from irrelevant sensory stimuli, is one of the early stages of information processing and cognition (Hall et al, 2010). Many recent studies shifted their focus to the prodromal period, which is experienced by 80–90% schizophrenics with less intense symptoms but does not meet the diagnostic criteria for schizophrenia (Addington and Barbato, 2012). Individuals in this period are referred to as ultra-high risk individuals (UHR), known as clinical risk individuals (Correll et al, 2010). Among them, Myles-Worsley et al (2004) studied the auditory sensory gating in genetically high risk and UHR prodromal adolescents and found that auditory sensory gating was impaired in both groups. Some studies (Yee et al, 1998; Brockhaus-Dumke et al, 2008) but not other studies (De Wilde et al, 2007; Hsieh et al, 2012; Van Tricht et al, 2015) have reported the sensory gating suppression in FESZ
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