Deficits in Sense of Body Ownership, Sensory Processing, and Temporal Perception in Schizophrenia Patients With/Without Auditory Verbal Hallucinations

Sensory and Multisensory Processing Changes and Their Contributions to Autism and Schizophrenia

Natural environments are typically multisensory, comprising information from multiple sensory modalities. It is in the integration of these incoming sensory signals that we form our perceptual gestalt that allows us to navigate through the world with relative ease. However, differences in multisensory integration (MSI) ability are found in a number of clinical conditions. Throughout this chapter, we discuss how MSI differences contribute to phenotypic characterization of autism and schizophrenia. Although these clinical populations are often described as opposite each other on a number of spectra, we describe similarities in behavioral performance and neural functions between the two conditions. Understanding the shared features of autism and schizophrenia through the lens of MSI research allows us to better understand the neural and behavioral underpinnings of both disorders. We provide potential avenues for remediation of MSI function in these populations.

Early auditory impairments as a candidate marker of attenuated sensory symptoms of psychosis

BACKGROUND AND HYPOTHESIS

Deficits in early auditory processing (EAP), as indexed by tone-matching performance, have been consistently demonstrated in individuals with schizophrenia spectrum disorders. However, the ontogeny of tone-matching deficits in schizophrenia remains relatively unknown. The current study aims to determine the relationship between clinical high risk for psychosis and EAP.

STUDY DESIGN

We employed a web-based screening approach to identify CHR individuals. A sample of 892 community dwelling participants completed the 16-tem version of the prodromal questionnaire (PQ16) for the assessment of attenuated psychotic symptoms, a 9-item questionnaire of perceptual and cognitive aberrations (PCA) for the assessment of basic symptoms and a tone-matching task.

STUDY RESULTS

505 (43.4 %) participants met cut-off criteria for attenuated psychotic symptoms (PQ16 ≥ 6 endorsed items), 614 (68.3 %) for basic symptoms (PCA ≥ 3 endorsed items), 647 (72.0 %) for either and 358 (40.1 %) for both of them. No significant differences in tone-matching performance were observed between CHR and non-CHR subjects, using either attenuated psychotic symptoms, basic symptoms, either or both cutoffs. In the CHR group screened with attenuated psychotic symptoms, auditory and tactile sensory symptoms were significantly associated with tone-matching deficits.

CONCLUSION

Tone-matching may not serve as a reliable biomarker for CHR status but rather a risk marker for the emergence of early sensory manifestations.

Aberrant salience signaling in auditory processing in schizophrenia: Evidence for abnormalities in both sensory processing and emotional reactivity

It has been long known that people with schizophrenia (SZ) have deficits in perceptual processing, including in the auditory domain. Furthermore, they often experience increased emotional responsivity and dysregulation, which further impacts overall functioning. Increased emotional responsivity to auditory stimuli is also seen in people with misophonia, a condition in which specific sounds elicit robust negative emotional responses. Given the role of emotional reactivity and dysregulation in the pathogenesis of SZ, our study investigated whether misophonia symptoms were elevated in SZ, or if people with SZ have a generalized increase in reactivity to sensory information. To explore the link between emotional reactivity to sound and more general aspects emotional reactivity and salience signaling in SZ, we used the Misophonia Questionnaire, the Sensory Processing Scale (SPS), and Aberrant Salience Inventory (ASI) in 30 people with SZ and 28 demographically-matched healthy volunteers (HVs). We found that people with SZ exhibited more emotional behavior associated with misophonia symptoms (specifically, distress in relation to sound) than HVs (t56 = 4.889, p < 0.001), but did not have elevated rates of misophonia overall. Also, sensory processing abnormalities and heightened emotional responses in people with SZ were not limited to the auditory domain but, rather, extended to all sensory modalities. Our results support the idea that SZ involves dysfunction in salience signaling, regarding auditory stimuli, but that abnormalities in salience signaling in SZ are more domain-general. These results highlight the importance of interventions designed to enhance emotion regulation in patients with SZ regarding stimuli in multiple modalities.

Aberrant heartbeat-evoked potential in schizophrenia

Self-disturbance is considered a core feature underlying the psychopathology of schizophrenia. Interoception has an important role in the development of a sense of self, leading to increased interest in the potential contribution of abnormal interoception to self-disturbances in schizophrenia. Several neuropsychological studies have demonstrated aberrant interoception in schizophrenia. However, cortical interoceptive processing has not yet been thoroughly investigated. Thus, we sought to examine resting-state heartbeat-evoked potential (HEP) in this population. We hypothesized that patients with schizophrenia would exhibit significant alterations in HEP compared to healthy controls (HCs). In this cross-sectional electroencephalogram (EEG) study, we compared the HEPs between age- and sex-matched groups of patients with schizophrenia and HCs. A 10-min resting-state EEG with eyes closed and an electrocardiogram (ECG) were recorded and analyzed for the time window of 450 ms to 500 ms after an ECG R peak. A positive HEP shift was observed in the frontal-central regions (F [1, 82] = 7.402, p = 0.008, partial η2 = 0.009) in patients with schizophrenia (n = 61) when compared with HCs (n = 31) after adjusting for confounders such as age, sex, and heart rate. A cluster-based correction analysis revealed that the HEP around the right frontal area (Fp2, F4, and F8) showed the most significant group differences (F [1, 82] = 10.079, p = 0.002, partial η2 = 0.021), with a peak at the F4 electrode site (F [1, 82] = 12.646, p < 0.001, partial η2 = 0.069). We observed no correlation between HEP and symptoms in patients with schizophrenia. A positive shift of HEP during the late component could reflect a trait abnormality in schizophrenia. Further research is required to determine the association between the altered cortical interoceptive processing indexed with HEP and self-disturbances in schizophrenia.

Examining the relationships between cognition and auditory hallucinations: A systematic review

OBJECTIVE

Auditory hallucinations (hearing voices) have been associated with a range of altered cognitive functions, pertaining to signal detection, source-monitoring, memory, inhibition and language processes. Yet, empirical results are inconsistent. Despite this, several theoretical models of auditory hallucinations persist, alongside increasing emphasis on the utility of a multidimensional framework. Thus, clarification of current evidence across the broad scope of proposed mechanisms is warranted.

METHOD

A systematic search of the Web of Science, PubMed and Scopus databases was conducted. Records were screened to confirm the use of an objective behavioural cognitive task, and valid measurement of hallucinations specific to the auditory modality.

RESULTS

Auditory hallucinations were primarily associated with difficulties in perceptual decision-making (i.e. reduced sensitivity/accuracy for signal-noise discrimination; liberal responding to ambiguity), source-monitoring (i.e. self-other and temporal context confusion), working memory and language function (i.e. reduced verbal fluency). Mixed or limited support was observed for perceptual feature discrimination, imagery vividness/illusion susceptibility, source-monitoring for stimulus form and spatial context, recognition and recall memory, executive functions (e.g. attention, inhibition), emotion processing and language comprehension/hemispheric organisation.

CONCLUSIONS

Findings were considered within predictive coding and self-monitoring frameworks. Of concern was the portion of studies which - despite offering auditory-hallucination-specific aims and inferences - employed modality-general measures, and/or diagnostic-based contrasts with psychologically healthy individuals. This review highlights disparities within the literature between theoretical conceptualisations of auditory hallucinations and the body of rigorous empirical evidence supporting such inferences. Future cognitive investigations, beyond the schizophrenia-spectrum, which explicitly define and measure the timeframe and sensory modality of hallucinations, are recommended.