EEG Theta Power and Coherence to Octave Illusion in First-Episode Paranoid Schizophrenia with Auditory Hallucinations

Abstract

Background: The exact mechanism behind auditory hallucinations in schizophrenia remains unknown. A corollary discharge dysfunction hypothesis has been put forward, but it requires further confirmation. Electroencephalography (EEG) of the Deutsch octave illusion might offer more insight, by demonstrating an abnormal cerebral activation similar to that under auditory hallucinations in schizophrenic patients. Methods: We invited 23 first-episode schizophrenic patients with auditory hallucinations and 23 healthy participants to listen to silence and two sound sequences, which consisted of alternating 400- and 800-Hz tones. EEG spectral power and coherence values of different frequency bands, including theta rhythm (3.5-7.5 Hz), were computed using 32 scalp electrodes. Task-related spectral power changes and task-related coherence differences were also calculated. Clinical characteristics of patients were rated using the Positive and Negative Syndrome Scale. Results: After both sequences of octave illusion, the task-related theta power change values of frontal and temporal areas were significantly lower, and the task-related theta coherence difference values of intrahemispheric frontal-temporal areas were significantly higher in schizophrenic patients than in healthy participants. Moreover, the task-related power change values in both hemispheres were negatively correlated and the task-related coherence difference values in the right hemisphere were positively correlated with the hallucination score in schizophrenic patients. Limitations: We only tested the Deutsch octave illusion in primary schizophrenic patients with acute first episode. Further studies might adopt other illusions or employ other forms of schizophrenia. Conclusion: Our results showed a lower activation but higher connection within frontal and temporal areas in schizophrenic patients under octave illusion. This suggests an oversynchronized but weak frontal area to exert an action to the ipsilateral temporal area, which supports the corollary discharge dysfunction hypothesis.

Hippocampal–prefrontal coherence mediates working memory and selective attention at distinct frequency bands and provides a causal link between schizophrenia and its risk gene GRIA1

“…This shows that the Gria1 -knockout-induced increase in local hippocampal peak theta power and peak theta coherence seen in the open field and SNP tests are state-dependent effects (rather than intrinsic changes resulting from GLUA1-ablation) and are determined by the relative novelty/familiarity of the environment. Interestingly, this recapitulates the endophenotype of elevated theta oscillations and theta coherence seen in patients with schizophrenia 8,9,11 , and has also been shown in another mouse model of reduced glutamatergic function ( Sp4 hypomorphs) 50 , which also has an attentional deficit. 51…”

“…This coherence between the local oscillations in interacting regions might enable the flexible routing of information between them 2–4 . Abnormalities in long-range coherence have been identified in patients with schizophrenia 5–9 and may underlie both cognitive and positive symptoms 6,10 . For example, studies in patients with schizophrenia have found abnormally increased baseline theta frequency coherence between multiple brain areas, whereby elevated fronto-temporal theta coherence correlates with positive symptom scores 8,9,11 .…”

“…Abnormalities in long-range coherence have been identified in patients with schizophrenia 5–9 and may underlie both cognitive and positive symptoms 6,10 . For example, studies in patients with schizophrenia have found abnormally increased baseline theta frequency coherence between multiple brain areas, whereby elevated fronto-temporal theta coherence correlates with positive symptom scores 8,9,11 . Moreover, those patients show a failure to transiently modulate theta coherence in response to sensory stimuli 11 .…”

Quantitative EEG reflects non-dopaminergic disease severity in Parkinson’s disease

“…In schizophrenic patients, auditory hallucinations were associated with task-related θ slowing (Zheng et al , 2015) and in cases with a delirium, visual hallucinations were associated with θ-δ slowing (Teeple et al , 2009). Although results of these studies based on other diseases may not be directly comparable with PD, we speculate that these findings suggest a more general cortical desynchronization, rather than network alterations that are specific to PD.…”

A Feasibility Study of LORETA Z-Score Neurofeedback Training in Adults with Schizophrenia-Spectrum Disorder Experiencing Treatment-Resistant Auditory Verbal Hallucinations

“…Other findings suggest a positive correlation between increased frequency of hallucinations and low frequency oscillations (i.e., delta and theta; Gattaz et al, 1992;Juszczak, 2011), which might also play a role in the generation of the emotionally charged hallucinations of abusive voices expressing personal insults (Nayani & David, 1996). More specifically, recent research has demonstrated the link between fronto-central theta power abnormalities and sensory processing deficits (Roa Romero et al, 2016), also proposing a role for fronto-temporal delta connectivity (Ford et al, 2002) and frontal/central/temporal theta power/coherence dysfunctions in patients with paranoid schizophrenia experiencing auditory hallucinations (Zheng et al, 2015). Furthermore, lower theta power in the hippocampus has been shown to precede AVH (Van Lutterveld et al, 2012).…”