Neurophysiological Mechanism Of Processing Octave Illusion In First-episode Paranoid Schizophrenia With Auditory Hallucinations

BackgroundSchizophrenia is a severe mental disorder with obscure etiology, unclear mechanism, and poor prognosis, and it has a devastated impact on society. The life prevalence of schizophrenia is about0.7%worldwide, and there are7.8million patients sufferers in China. Auditory hallucination is one of the core symptoms in schizophrenia, and believed to affect70-75%patients. The hallucination is closely related to the severity and prognosis of schizophrenia. Due to the relationship between auditory illusion and auditory hallucination, such as the same cerebral areas involved, we believe that the investigating on the cerebral processing of auditory illusion might partly uncover the mechanisms under auditory hallucination.AimsTo characterize the cerebral processing patterns of octave illusion, and to correlate them with the clinical sympotoms of schizophrenia.Methods1) Firstly, we administered the octave illusion in29healthy volunteers, who were later divided into two groups according to their reporting sides after hearing the illusion, i.e., reporting left (RL) vs.right (RR).Secondly, we trialed the illusion tests in23patients suffering from the first-episode schizophrenia with auditory hallucination, and in23age and gender-balanced healthy volunteers.2) We also used the Positive and Negative Syndrome Scale (PANSS) to measure the symptom severity of schizophrenia.3) We recorded EEG of our participants when they were hearing silence, normal and reversed sequences of octave illusion.4) The EEG power/task-related power and coherence/task-related coherence were analyzed between groups, hemispheres, episodes and electrodes/electrode pairs with the multiple-way ANOVA (MANOVA).Results1) In healthy participants, during normal and reversed sequences of octave illusion, the task-related power was higher in the right frontal-temporal area than that in left in RR group; the task-related coherence in right frontal-temporal area was also higher in RR group.2) In.schizophrenia.patients.during normal and reversed sequences, the task-related power changes of both ipsilateral frontal-temporal areas were lower and both ipsilateral task-related coherences in right frontal-temporal areas were higher than those of healthy volunteers.3) In.schizophrenia.patients.the task-related power change in right frontal-temporal areas were negatively correlated with the PANSS hallucination score, and the task-related coherence differences in right frontal-temporal areas were positively correlated with the PANSS hallucination score.Conclusion1) In healthy right-handers, when processing the octave illusion, the right ear predominance was associated with a specific reactivity of the frontal-temporal regions. 2) In healthy right-handers, the ear preference was associated with a pronounced frontal-temporal neuronal activity.3) During octave illusion, schizophrenia displayed lower activity and higher synchronization in the mediofrontal-temporal regions.4) When processing the octave illusion, schizophrenia patients had an integrative dysfunction, such as those in the self-monitoring, inhibition and compensation.5) The lower activity and higher synchronization in the frontal-temporal regions partly.uncover.the.mechanisms.of.hallucination.pathway.in.schizophrenia.In.general,the. right.ear.predominance.during.octave.illusion.processing.was associated with a specific reactivity of the frontal-temporal regions and different frontal-temporal pathway. During the illusory processing, the first episode hallucinating schizophrenia showed lower activity and higher synchronization in mediofrontal-temporal regions, which were correlated with clinical hallucination symptom. Our results therefore have provided some neurophysiological evidence to support the corollary discharge theory of hallucination in schizophrenia.