Auditory verbal hallucinations result from combinatoric associations of multiple neural events

The phenomenology of auditory verbal hallucinations in schizophrenia and the challenge from pseudohallucinations

In trying to make sense of the extensive phenomenological variation of first-personal reports on auditory verbal hallucinations, the concept of pseudohallucination is originally introduced to designate any hallucinatory-like phenomena not exhibiting some of the paradigmatic features of "genuine" hallucinations. After its introduction, Karl Jaspers locates the notion of pseudohallucinations into the auditory domain, appealing to a distinction between hallucinatory voices heard within the subjective inner space (pseudohallucination) and voices heard in the outer external space (real hallucinations) with differences in their sensory richness. Jaspers' characterization of the term has been the target of a number of phenomenological, conceptual and empirically-based criticisms. From this latter point of view, it has been claimed that the concept cannot capture distinct phenomena at the neurobiological level. Over the last years, the notion of pseudohallucination seems to be falling into disuse as no major diagnostic system seems to refer to it. In this paper, we propose that even if the concept of pseudohallucination is not helpful to differentiate distinct phenomena at the neurobiological level, the inner/outer distinction highlighted by Jaspers' characterization of the term still remains an open explanatory challenge for dominant theories about the neurocognitive origin of auditory verbal hallucinations. We call this, "the challenge from pseudohallucinations". After exploring this issue in detail, we propose some phenomenological, conceptual, and empirical paths for future research that might help to build up a more contextualized and dynamic view of auditory verbal hallucinatory phenomena.

Functional Decoupling of Language and Self-Reference Networks in Patients with Persistent Auditory Verbal Hallucinations

BACKGROUND

Accumulating neuroimaging evidence suggests that abnormal intrinsic neural activity could underlie auditory verbal hallucinations (AVH) in patients with schizophrenia. However, little is known about the functional interplay between distinct intrinsic neural networks and their association with AVH.

METHODS

We investigated functional network connectivity (FNC) of distinct resting-state networks as well as the relationship between FNC strength and AVH symptom severity. Resting-state functional MRI data at 3 T were obtained for 14 healthy controls and 10 patients with schizophrenia presenting with persistent AVH. The data were analyzed using a spatial group independent component analysis, followed by constrained maximal lag correlations to determine FNC within and between groups.

RESULTS

Four components of interest, comprising language, attention, executive control networks, as well as the default-mode network (DMN), were selected for subsequent FNC analyses. Patients with persistent AVH showed lower FNC between the language network and the DMN (p < 0.05, corrected for false discovery rate). FNC strength, however, was not significantly related to symptom severity, as measured by the Psychotic Symptom Rating Scale.

CONCLUSION

These findings suggest that disrupted FNC between a speech-related system and a network subserving self-referential processing is associated with AVH. The data are consistent with a model of disrupted self-attribution of speech generation and perception.

Abnormal Local Activity and Functional Dysconnectivity in Patients with Schizophrenia Having Auditory Verbal Hallucinations

Auditory verbal hallucination (AVH) is emphasized as a pathological hallmark of schizophrenia. Neuroimaging studies provide evidence linking AVH to overlapping functional abnormalities in distributed networks. However, no clear conclusion has still been reached. This study aimed to further explore the brain activity of patients with schizophrenia having AVH from both local activity (LA) and functional connectivity (FC) insights, while excluding confounding factors from other positive symptoms. A total of 42 patients with AVH (AVH patients group, APG), 26 without AVH (non-AVH patients group, NPG), and 82 normal controls (NC) underwent resting-state functional magnetic resonance imaging (fMRI). LA measures, including regional homogeneity (ReHo) and fractional amplitude of low-frequency fluctuations (fALFF), and FC measures were evaluated to understand the neuroimaging mechanism of AVH. APG showed increased ReHo and fALFF in the bilateral putamen (Put) compared with NPG and NC. FC analysis (using bilateral putamen as seeds) revealed that all patients showed abnormal FC of multiple resting-state network regions, including the anterior and post cingulate cortex, middle frontal gyrus, inferior parietal gyrus, and left angular gyrus. Interestingly, APG showed significantly decreased FC of insula extending to the superior temporal gyrus and inferior frontal gyrus compared with NPG and NC. The present findings suggested a significant correlation of abnormal LA and dysfunctional putamen-auditory cortical connectivity with the neuropathological mechanism of AVH, providing evidence for the functional disconnection hypothesis of schizophrenia.

White Matter Microstructural Abnormalities in the Broca's-Wernicke's-Putamen "Hoffman Hallucination Circuit" and Auditory Transcallosal Fibers in First-Episode Psychosis With Auditory Hallucinations

BACKGROUND

Functional connectivity abnormalities between Broca's and Wernicke's areas and the putamen revealed by functional magnetic resonance imaging (fMRI) are related to auditory hallucinations (AH). In long-term schizophrenia, reduced white matter structural integrity revealed by diffusion imaging in left arcuate fasciculus (connecting Broca's and Wernicke's areas) is likely related to AH. The structural integrity of connections with putamen and their relation to AH are unknown. Little is known about this relationship in first-episode psychosis (FEP), although auditory transcallosal connections were reported to play a role. White matter in the Broca's-Wernicke's-putamen language-related circuit and auditory transcallosal fibers was examined to investigate associations with AH in FEP.

METHODS

White matter connectivity was measured in 40 FEP and 32 matched HC using generalized fractional anisotropy (gFA) derived from diffusion spectrum imaging (DSI).

RESULTS

FEP and HC did not differ in gFA in any fiber bundle. In FEP, AH severity was significantly inversely related to gFA in auditory transcallosal fibers and left arcuate fasciculus. Although the right hemisphere arcuate fasciculus-AH association did not attain significance, the left and right arcuate fasciculus associations were not significantly different.

CONCLUSIONS

Despite overall normal gFA in FEP, AH severity was significantly related to gFA in transcallosal auditory fibers and the left hemisphere connection between Broca's and Wernicke's areas. Other bilateral tracts' gFA were weakly associated with AH. At the first psychotic episode, AH are more robustly associated with left hemisphere arcuate fasciculus and interhemispheric auditory fibers microstructural deficits, likely reflecting mistiming of information flow between language-related cortical centers.

The Self, Agency and Spatial Externalizations of Inner Verbal Thoughts, and Auditory Verbal Hallucinations

Aim: Auditory Verbal Hallucinations (AVH) are experienced as the "voices" of others (O-AVH) or self (S-AVH) in internal space/inside the head (IS-AVH) or external space (ES-AVH), and are considered to result from agency and spatial externalizations of inner speech. Both types of externalizations are conflated, and the relationship between these externalizations and AVH experiences is unclear. In this paper, I investigate the relationship between cognitive agency and spatial externalizations and between these externalizations and the types of AVH experience. Method: Twenty-five patients with history of AVH and 24 matched healthy controls performed agency and spatial distinction tasks: distinction between self-generated (read) (S) sentences and other-generated (O) sentences, and between sentences read silently (experienced in internal space, IS) and sentences read aloud (experienced in external space, ES). Regression analyses between misattribution biases (S-O vs. IS-ES, and O-S vs. ES-IS) were obtained. t tests were used to compare misattribution biases between AVH subtypes (S-AVH vs. O-AVH, and IS-AVH vs. ES-AVH). Results: Regressions suggest that agency distinction is independent from spatial distinction in both groups. O-AVH and S-AVH subgroups differed only with respect to S-O bias, and IS-AVH and ES-AVH subgroups differed only with respect to IS-ES bias. Conclusion: These results suggest that agency and spatial externalizations of inner speech are independent at phenomenological and cognitive and levels; and that these externalizations are co-related across levels. I discuss the implications of these findings in the wider context of research on AVH and on the experience of self.

Are there clinical differences between inner, outer or dual spatial locations of auditory verbal hallucinations?

The aim of the present exploratory study was to examine the clinical differences of Auditory Verbal Hallucinations (AVHs) according to their spatial localization. Sixty-six outpatients were divided into three separate groups: inner, external and dual AVHs. The three groups were compared on sociodemographic variables (age, gender, education, marital status, living situation, employment, social disability), on clinical psychiatric characteristics (diagnosis, medication, comorbidities, illness onset, illness duration and hospitalizations) and on the measure yielded by the clinical assessments (Brief Psychiatric Rating Scale-Expanded, version 4.0; Maastricht Voices Interview for Adults; Belief About Voices Questionnaire Revised, the Clinical Global Impression, the Global Assessment Functioning Self-Esteem Rating Short Form, the World Health Organisation Quality of Life-Bref). Gender, living situation, social quality of life and some items regarding beliefs about AVHs raised significant difference, however most of the other comparisons failed to reach significance. Taken together, our findings suggest that all AVHs subtypes have equal clinical significance in patients presenting a chronic mental illness. However, the power of the study limits the generalization of the findings. Clinical implications of the findings are proposed.

Tailoring Cognitive Behavioral Therapy to Subtypes of Voice-Hearing

Cognitive behavioral therapy (CBT) for voice-hearing (i.e., auditory verbal hallucinations; AVH) has, at best, small to moderate effects. One possible reason for this limited efficacy is that current CBT approaches tend to conceptualize voice-hearing as a homogenous experience in terms of the cognitive processes involved in AVH. However, the highly heterogeneous nature of voice-hearing suggests that many different cognitive processes may be involved in the etiology of AVH. These heterogeneous voice-hearing experiences do, however, appear to cluster into a set of subtypes, opening up the possibility of tailoring treatment to the subtype of AVH that a voice-hearer reports. In this paper, we (a) outline our rationale for tailoring CBT to subtypes of voice-hearing, (b) describe CBT for three putative subtypes of AVH (inner speech-based AVH, memory-based AVH, and hypervigilance AVH), and (c) discuss potential limitations and problems with such an approach. We conclude by arguing that tailoring CBT to subtypes of voice-hearing could prove to be a valuable therapeutic development, which may be especially effective when used in early intervention in psychosis services.

Hearing it right: Evidence of hemispheric lateralization in auditory imagery

An advantage of the right ear (REA) in auditory processing (especially for verbal content) has been firmly established in decades of behavioral, electrophysiological and neuroimaging research. The laterality of auditory imagery, however, has received little attention, despite its potential relevance for the understanding of auditory hallucinations and related phenomena. In Experiments 1-4 we find that right-handed participants required to imagine hearing a voice or a sound unilaterally show a strong population bias to localize the self-generated auditory image at their right ear, likely the result of left-hemispheric dominance in auditory processing. In Experiments 5-8 - by means of the same paradigm - it was also ascertained that the right-ear bias for hearing imagined voices depends just on auditory attention mechanisms, as biases due to other factors (i.e., lateralized movements) were controlled. These results, suggesting a central role of the left hemisphere in auditory imagery, demonstrate that brain asymmetries can drive strong lateral biases in mental imagery.

Subcortical modulation in auditory processing and auditory hallucinations

Hearing perception in individuals with auditory hallucinations has not been well studied. Auditory hallucinations have previously been shown to involve primary auditory cortex activation. This activation suggests that auditory hallucinations activate the terminal of the auditory pathway as if auditory signals are submitted from the cochlea, and that a hallucinatory event is therefore perceived as hearing. The primary auditory cortex is stimulated by some unknown source that is outside of the auditory pathway. The current study aimed to assess the outcomes of stimulating the primary auditory cortex through the auditory pathway in individuals who have experienced auditory hallucinations. Sixteen patients with schizophrenia underwent functional magnetic resonance imaging (fMRI) sessions, as well as hallucination assessments. During the fMRI session, auditory stimuli were presented in one-second intervals at times when scanner noise was absent. Participants listened to auditory stimuli of sine waves (SW) (4-5.5kHz), English words (EW), and acoustically reversed English words (arEW) in a block design fashion. The arEW were employed to deliver the sound of a human voice with minimal linguistic components. Patients' auditory hallucination severity was assessed by the auditory hallucination item of the Brief Psychiatric Rating Scale (BPRS). During perception of arEW when compared with perception of SW, bilateral activation of the globus pallidus correlated with severity of auditory hallucinations. EW when compared with arEW did not correlate with auditory hallucination severity. Our findings suggest that the sensitivity of the globus pallidus to the human voice is associated with the severity of auditory hallucination.

Evaluation of auditory hallucinations in patients with schizophrenia: A validation study of the Malay version of Psychotic Symptom Rating Scales (PSYRATS)

The Psychotic Symptom Rating Scales (PSYRATS) is the most widely used validated scale to measure the specific symptoms of auditory hallucination and delusion. The aim of this study was to validate and to examine the psychometric properties of the auditory hallucination component of the Malay PSYRATS (MyPSYRATS). The research was done in the Universiti Kebangsaan Malaysia Medical Center (UKMMC) among 51 schizophrenia inpatients and outpatients who had experienced or reported verbal auditory hallucination. The psychometric properties of MyPSYRATS (auditory hallucination) were studied and a comparison was made between the psychometric properties obtained and the Positive and Negative Syndrome Scale (PANSS). The internal consistency of MyPSYRATS was good as revealed by Cronbach's alpha value. Factor analysis replicated three components (emotional, cognitive, and physical) similar to the factorial structure of the original auditory hallucination scale. However, two items were regrouped under the emotional component. Spearman's rank-order correlation showed a significant positive relationship between the total score of auditory hallucinations and PANSS auditory hallucinations item (P3). In conclusion, the auditory hallucination domain of MyPSYRATS is a reliable and valid assessment tool for further clinical applications.

A Neuropsychological Approach to Auditory Verbal Hallucinations and Thought Insertion - Grounded in Normal Voice Perception

A neuropsychological perspective on auditory verbal hallucinations (AVH) links key phenomenological features of the experience, such as voice location and identity, to functionally separable pathways in normal human audition. Although this auditory processing stream (APS) framework has proven valuable for integrating research on phenomenology with cognitive and neural accounts of hallucinatory experiences, it has not yet been applied to other symptoms presumed to be closely related to AVH – such as thought insertion (TI). In this paper, I propose that an APS framework offers a useful way of thinking about the experience of TI as well as AVH, providing a common conceptual framework for both. I argue that previous self-monitoring theories struggle to account for both the differences and similarities in the characteristic features of AVH and TI, which can be readily accommodated within an APS framework. Furthermore, the APS framework can be integrated with predictive processing accounts of psychotic symptoms; makes predictions about potential sites of prediction error signals; and may offer a template for understanding a range of other symptoms beyond AVH and TI.

Better than mermaids and stray dogs? Subtyping auditory verbal hallucinations and its implications for research and practice

The phenomenological diversity of auditory verbal hallucinations (AVH) is not currently accounted for by any model based around a single mechanism. This has led to the proposal that there may be distinct AVH subtypes, which each possess unique (as well as shared) underpinning mechanisms. This could have important implications both for research design and clinical interventions because different subtypes may be responsive to different types of treatment. This article explores how AVH subtypes may be identified at the levels of phenomenology, cognition, neurology, etiology, treatment response, diagnosis, and voice hearer's own interpretations. Five subtypes are proposed; hypervigilance, autobiographical memory (subdivided into dissociative and nondissociative), inner speech (subdivided into obsessional, own thought, and novel), epileptic and deafferentation. We suggest other facets of AVH, including negative content and form (eg, commands), may be best treated as dimensional constructs that vary across subtypes. After considering the limitations and challenges of AVH subtyping, we highlight future research directions, including the need for a subtype assessment tool.

A synthesis of evidence on inhibitory control and auditory hallucinations based on the Research Domain Criteria (RDoC) framework

The National Institute of Mental Health initiative called the Research Domain Criteria (RDoC) project aims to provide a new approach to understanding mental illness grounded in the fundamental domains of human behavior and psychological functioning. To this end the RDoC framework encourages researchers and clinicians to think outside the [diagnostic] box, by studying symptoms, behaviors or biomarkers that cut across traditional mental illness categories. In this article we examine and discuss how the RDoC framework can improve our understanding of psychopathology by zeroing in on hallucinations- now widely recognized as a symptom that occurs in a range of clinical and non-clinical groups. We focus on a single domain of functioning-namely cognitive [inhibitory] control-and assimilate key findings structured around the basic RDoC "units of analysis," which span the range from observable behavior to molecular genetics. Our synthesis and critique of the literature provides a deeper understanding of the mechanisms involved in the emergence of auditory hallucinations, linked to the individual dynamics of inhibitory development before and after puberty; favors separate developmental trajectories for clinical and non-clinical hallucinations; yields new insights into co-occurring emotional and behavioral problems; and suggests some novel avenues for treatment.