Results: The schizophrenia patients expressed later habituation onset ( p < 0.01) and hyper-activity in both lateral frontal–temporal cortices than controls ( p = 0.001). Source reconstruction and dynamic causal modeling (DCM) analysis were performed to estimate the effective connectivity and casual relationship between frontal and temporal regions before and after habituation. Methods: A dichotic listening paradigm was performed with simultaneous EEG recording on 22 schizophrenia patients and 22 gender- and age-matched healthy controls. The present study is aim to find the casual relationship and mechanisms of excitatory–inhibitory (E/I) dysfunctions in schizophrenia (SCZ) via habituation. These findings are consistent with the notion that the brain continually maintains a detailed representation of ongoing sensory input and that this representation shapes the processing of incoming information.īackground: Habituation is considered to have protective and filtering mechanisms. Responses show a period of adjustment to the rule change, followed by a return to tracking the predictability of the sequence. Regular patterns transitioned to a different rule, keeping the frequency content constant.
#AUDITORY ILLUSIONS UPDATE#
Chapter 7 concerns the ability of the brain to update an existing model. However, this effect was not present when the violation comprised a silent gap. Outlier tones within regular sequences evoked a larger response than matched outliers in random sequences. Chapters 5 and 6 present behavioural and EEG experiments where violations are inserted in the sequences. The brain’s internal model can be investigated via the response to rule violations. Results indicate a system for automatic predictability monitoring which is distinct from, but concurrent with, repetition suppression. Chapter 4 presents a study which reconciles auditory sequence predictability and repetition in a single paradigm.
However, the patterns used in this thesis show the opposite effect, where predictable patterns show a strongly enhanced brain response, compared to frequency-matched random sequences. Responses to repetitive stimulation generally exhibit suppression, thought to form a building block of regularity learning. Behavioural experiments investigate attentional capture by stimulus structure, suggesting that regular sequences are easier to ignore. In Chapter 3, EEG data demonstrate fast recognition of predictable patterns, shown by an increase in responses to regular relative to random sequences. Stimuli comprised tone sequences, with frequencies varying in regular or random patterns. Experimental chapters 3-7 address different effects arising from statistical predictability, stimulus repetition and surprise. This thesis uses specifically structured sound sequences, with electroencephalography (EEG) recording and behavioural tasks, to understand how the brain forms and updates a model of the auditory world. The study had demonstrated that when interpreting the illusion stimuli, patients with cluster A personality disorders would mobilize more cognitive processes relating to their personality-specific traits. The paranoid and schizoid personality disorder patients reported more meaningful Chinese words than the healthy volunteers did when they were listening to the "Harvey" word illusion, and more meaningful Chinese words which were corresponding to the DSM-5 pathological personality traits than the healthy volunteers did.
We therefore invited 11 patients with paranoid, 34 schizoid, and 13 schizotypal personality disorders, and 116 healthy volunteers, to report the Chinese words when they were listening to the Deutsch "High-Low" and "Harvey" word illusions. Whether the phenomenon would be more pronounced in patients with personality disorders, especially the cluster A types remains unknown. The meaningful words reported by the healthy people when listening to the Deutsch word illusion were correlated with the normal personality traits.
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