The perceptual characteristics of voice-hallucinations in deaf people: insights into the nature of subvocal thought and sensory feedback loops

Sensory Deprivation and Psychiatric Disorders: Association, Assessment and Management Strategies

BACKGROUND

Sensory deprivation (SD) is a widely prevalent condition that leads to various health-related consequences and is also an important cause of disability worldwide. Earlier, SD experiments were used as research modalities to alter human behavior. In recent years, the focus has shifted to understand how SD can affect the mental health of individuals (with congenital or acquired sensory impairments). This narrative review focuses on the current understanding about the association of SD and psychiatric disorders.

METHODS

A comprehensive literature search was done PubMed, Scopus, PsycINFO, and Google Scholar and in the cross-references of relevant articles. Keywords included "sensory deprivation," "blindness," "deafness," "mental illness," "psychiatric disorders," "prevalence," "assessment," and "management" in various combinations. Only original articles (abstract and full text) published in English till October 2020 were included.

RESULTS

The prevalence of anxiety, depression, dementia, suicidality, and psychosis in persons with SD is higher than the general population (highest being in persons with dementia with comorbid SD). Several mechanisms/hypotheses have been proposed to explain these associations. Assessment of SD includes a thorough history taking, with adequate awareness about the difficulties faced during a psychiatric interview in this population. Modifications in the psychometric assessment procedures are warranted. Management depends on a multi-disciplinary approach that includes proper referral to specialties, pharmacological management (depending on diagnosis as well as taking care of ototoxic/ocular side-effect profile of the drugs), and nonpharmacological supportive measures.

CONCLUSIONS

SD is a complex condition, and evidence suggests that persons with SD have higher psychiatric morbidity. A comprehensive assessment, along with holistic management approach is warranted.

A voice without a mouth no more: The neurobiology of language and consciousness

Most research on the neurobiology of language ignores consciousness and vice versa. Here, language, with an emphasis on inner speech, is hypothesised to generate and sustain self-awareness, i.e., higher-order consciousness. Converging evidence supporting this hypothesis is reviewed. To account for these findings, a 'HOLISTIC' model of neurobiology of language, inner speech, and consciousness is proposed. It involves a 'core' set of inner speech production regions that initiate the experience of feeling and hearing words. These take on affective qualities, deriving from activation of associated sensory, motor, and emotional representations, involving a largely unconscious dynamic 'periphery', distributed throughout the whole brain. Responding to those words forms the basis for sustained network activity, involving 'default mode' activation and prefrontal and thalamic/brainstem selection of contextually relevant responses. Evidence for the model is reviewed, supporting neuroimaging meta-analyses conducted, and comparisons with other theories of consciousness made. The HOLISTIC model constitutes a more parsimonious and complete account of the 'neural correlates of consciousness' that has implications for a mechanistic account of mental health and wellbeing.

Longitudinal Course of Illness in Congenitally Deaf Patient with Auditory Verbal Hallucination

Auditory verbal hallucination is one of the core symptoms of schizophrenia, same as delusions, and also occurs in many other psychiatric disorders. Significant numbers of people with congenital deafness experience auditory verbal hallucinations; however, there are only a few reports regarding the course of psychosis in people with congenital deafness. Herein, we report the case of a patient with congenital deafness and auditory verbal hallucinations whose diagnosis was changed from psychotic major depression to schizophrenia 7 years after the onset of the disease. His psychotic symptoms decreased when his primary medication was changed from an antidepressant to antipsychotic drugs, based on the change of diagnosis. In the treatment of congenitally deaf patients with auditory verbal hallucinations, the inability to communicate through spoken language may interfere with proper diagnosis and treatment. The ability to collect detailed information in ways other than through verbal language is imperative for psychiatrists to determine the appropriate diagnosis and treatment for these patients during the longitudinal course of illness.

The origins of music in (musi)language

The view of music as a byproduct of other cognitive functions has been deemed incomplete or incorrect. Revisiting the six lines of evidence that support this conclusion, it is argued that it is unclear how the hypothesis that music has its origins in (musi)language is discarded. Two additional promising research lines that can support or discard the byproduct hypothesis are presented.

Deficits in access consciousness, integrative function, and consequent autonoetic thinking in schizophrenia

Alterations within consciousness in schizophrenia can be evidenced by impediments in self-awareness and loss of agency. Ned Block's definition of access consciousness is applied in order to further delineate cognitive deficits involving reflective thought and autonoetic thinking in persons with schizophrenia. Current theories on the nature and functioning of consciousness are discussed, which include Global Workspace Theory and metarepresentational characterizations. These describe a recursive, integrative quality to consciousness, contributed to by the functions of access consciousness, that is relevant in examining cognitive deficits in schizophrenia. The integrative deficit that is described as operating in conscious process involves a failure to incorporate prior outputs from a separate cognitive task and integrate these into a novel working schema. The alterations in access consciousness in persons with schizophrenia appear to be a consequence of disrupted integrative cognitive functions. An anteceding problem with cortical circuits involving integrative functions related to access consciousness is therefore hypothesized to manifest as subsequent cognitive dysfunction that leads to symptoms of schizophrenia. Constitutive failures to integrate information in schizophrenia could lead to an inability to create experiential unity and manage content in autonoetic consciousness. Some of the aberrant reasoning manifested by persons with schizophrenia, including problems with hierarchical relational reasoning, model-based-learning, J-con, ipseity, and source monitoring, could also reflect alterations in access consciousness, and their investigation offers additional approaches for scientific inquiry.

A possible key role of vision in the development of schizophrenia

Based on a brief overview of the various aspects of schizophrenia reported by numerous studies, here we hypothesize that schizophrenia may originate (and in part be performed) from visual areas. In other words, it seems that a normal visual system or at least an evanescent visual perception may be an essential prerequisite for the development of schizophrenia as well as of various types of hallucinations. Our study focuses on auditory and visual hallucinations, as they are the most prominent features of schizophrenic hallucinations (and also the most studied types of hallucinations). Here, we evaluate the possible key role of the visual system in the development of schizophrenia.

Misinterpretation of Psychiatric Illness in Deaf Patients: Two Case Reports

The Deaf/hard of hearing population is growing rapidly and the medical community is facing a higher demand for this special needs group. The Deaf culture is unique in that spoken word is via sign language. What one person may see as mania or psychosis is actually a norm with Deaf individuals. The fear of the unknown language often creates immediate conclusions that are false. As such, being culturally sensitive becomes a large component of properly assessing a Deaf patient in any psychiatric situation. In the first case, the patient is a 26-year-old prelingually Deaf male, who was placed under an involuntary hold by the emergency room physician for acting erratic and appearing to respond to internal stimuli. The patient was later interviewed with an interpreter and stated he became upset because the staff was not providing him proper care as they lacked an ability to communicate with him. The patient's family was called who corroborated the story and requested he be discharged. Case two presents with a 30-year-old Hispanic male who is also prelingually Deaf. He was admitted involuntary for bizarre behavior and delusions, with a past diagnosis of schizophrenia. Upon interview, the patient endorsed delusions via written language; however, through an ASL-language interpreter he was able to convey a linear and coherent thought process. Caring for special needs patients must be in the repertoire of any trained healthcare professional. Deaf Individuals experience mental illness just like the general population. Symptoms such as auditory hallucinations are not brought up in the same manner and are thought to be a visual construct interpreted by the patient as a vocal expression. It is imperative that these subtle differences are known in order to differentiate out an actual mental illness. In any case where language is a barrier, an interpreter must be present for a thorough assessment. These cases lend further thought into policy reform for Deaf individuals within healthcare.

Relating to the Speaker behind the Voice: What Is Changing?

We introduce therapeutic techniques that encourage voice hearers to view their voices as coming from intentional agents whose behavior may be dependent on how the voice hearer relates to and interacts with them. We suggest that this approach is effective because the communicative aspect of voice hearing might fruitfully be seen as explanatorily primitive, meaning that the agentive aspect, the auditory properties, and the intended meaning (interpretation) are all necessary parts of the experience, which contribute to the impact the experience has on the voice hearer. We examine the experiences of a patient who received Relating Therapy, and explore the kinds of changes that can result from this therapeutic approach.

The Representation of Agents in Auditory Verbal Hallucinations

Current models of auditory verbal hallucinations (AVHs) tend to focus on the mechanisms underlying their occurrence, but often fail to address the content of the auditory experience. In other words, they tend to ask why there are AVHs at all, instead of asking why, given that there are AVHs, they have the properties that they have. One such property, which has been largely overlooked and which we will focus on here, is why the voices are often experienced as coming from (or being the voices of) agents, and often specific, individualised agents. In this article, we argue not only that the representation of agents is important in accurately describing many cases of AVH, but also that deeper reflection on what is involved in the representation of agents has potentially vital consequences for our aetiological understanding of AVH, namely, for understanding how and why AVHs come about.

Auditory verbal hallucinations: Social, but how?

Auditory verbal hallucinations (AVH) are experiences of hearing voices in the absence of an external speaker. Standard explanatory models propose that AVH arise from misattributed verbal cognitions (i.e. inner speech), but provide little account of how heard voices often have a distinct persona and agency. Here we review the argument that AVH have important social and agent-like properties and consider how different neurocognitive approaches to AVH can account for these elements, focusing on inner speech, memory, and predictive processing. We then evaluate the possible role of separate social-cognitive processes in the development of AVH, before outlining three ways in which speech and language processes already involve socially important information, such as cues to interact with others. We propose that when these are taken into account, the social characteristics of AVH can be explained without an appeal to separate social-cognitive systems.

Inner Speech: Development, Cognitive Functions, Phenomenology, and Neurobiology

Inner speech-also known as covert speech or verbal thinking-has been implicated in theories of cognitive development, speech monitoring, executive function, and psychopathology. Despite a growing body of knowledge on its phenomenology, development, and function, approaches to the scientific study of inner speech have remained diffuse and largely unintegrated. This review examines prominent theoretical approaches to inner speech and methodological challenges in its study, before reviewing current evidence on inner speech in children and adults from both typical and atypical populations. We conclude by considering prospects for an integrated cognitive science of inner speech, and present a multicomponent model of the phenomenon informed by developmental, cognitive, and psycholinguistic considerations. Despite its variability among individuals and across the life span, inner speech appears to perform significant functions in human cognition, which in some cases reflect its developmental origins and its sharing of resources with other cognitive processes.

The speaker behind the voice: therapeutic practice from the perspective of pragmatic theory

Many attempts at understanding auditory verbal hallucinations have tried to explain why there is an auditory experience in the absence of an appropriate stimulus. We suggest that many instance of voice-hearing should be approached differently. More specifically, they could be viewed primarily as hallucinated acts of communication, rather than hallucinated sounds. We suggest that this change of perspective is reflected in, and helps to explain, the successes of two recent therapeutic techniques. These two techniques are: Relating Therapy for Voices and Avatar Therapy.

Sound representation in higher language areas during language generation

How language is encoded by neural activity in the higher-level language areas of humans is still largely unknown. We investigated whether the electrophysiological activity of Broca's area correlates with the sound of the utterances produced. During speech perception, the electric cortical activity of the auditory areas correlates with the sound envelope of the utterances. In our experiment, we compared the electrocorticogram recorded during awake neurosurgical operations in Broca's area and in the dominant temporal lobe with the sound envelope of single words versus sentences read aloud or mentally by the patients. Our results indicate that the electrocorticogram correlates with the sound envelope of the utterances, starting before any sound is produced and even in the absence of speech, when the patient is reading mentally. No correlations were found when the electrocorticogram was recorded in the superior parietal gyrus, an area not directly involved in language generation, or in Broca's area when the participants were executing a repetitive motor task, which did not include any linguistic content, with their dominant hand. The distribution of suprathreshold correlations across frequencies of cortical activities varied whether the sound envelope derived from words or sentences. Our results suggest the activity of language areas is organized by sound when language is generated before any utterance is produced or heard.

What is that little voice inside my head? Inner speech phenomenology, its role in cognitive performance, and its relation to self-monitoring

The little voice inside our head, or inner speech, is a common everyday experience. It plays a central role in human consciousness at the interplay of language and thought. An impressive host of research works has been carried out on inner speech these last fifty years. Here we first describe the phenomenology of inner speech by examining five issues: common behavioural and cerebral correlates with overt speech, different types of inner speech (wilful verbal thought generation and verbal mind wandering), presence of inner speech in reading and in writing, inner signing and voice-hallucinations in deaf people. Secondly, we review the role of inner speech in cognitive performance (i.e., enhancement vs. perturbation). Finally, we consider agency in inner speech and how our inner voice is known to be self-generated and not produced by someone else.

Assessment and treatment of deaf adults with psychiatric disorders: a review of the literature for practitioners

Many deaf individuals comprise a unique cultural and linguistic minority group. This article reviews the current research literature related to the evaluation, diagnosis, and treatment of culturally deaf individuals suffering from mental disorders. Appropriate psychiatric assessment and treatment requires that clinicians be sensitive to issues of language and differences in social norms and cultural values. Emerging trends in research indicate greater diagnostic specificity and a broader range of diagnoses being assigned in services that are specialized for the treatment of deaf people with mental health issues. Culturally sensitive evaluation and treatment involves a thorough assessment of language modality and language fluency, deafness/audiological history, and cultural identification. Failure to consider these factors during the mental status exam can lead to misdiagnosis. Important issues that confound differential diagnosis and psychiatric treatment of the deaf population are highlighted and discussed. Recommendations for the provision of culturally and linguistically appropriate care are provided.

Cognitive and neuroplasticity mechanisms by which congenital or early blindness may confer a protective effect against schizophrenia

Several authors have noted that there are no reported cases of people with schizophrenia who were born blind or who developed blindness shortly after birth, suggesting that congenital or early (C/E) blindness may serve as a protective factor against schizophrenia. By what mechanisms might this effect operate? Here, we hypothesize that C/E blindness offers protection by strengthening cognitive functions whose impairment characterizes schizophrenia, and by constraining cognitive processes that exhibit excessive flexibility in schizophrenia. After briefly summarizing evidence that schizophrenia is fundamentally a cognitive disorder, we review areas of perceptual and cognitive function that are both impaired in the illness and augmented in C/E blindness, as compared to healthy sighted individuals. We next discuss: (1) the role of neuroplasticity in driving these cognitive changes in C/E blindness; (2) evidence that C/E blindness does not confer protective effects against other mental disorders; and (3) evidence that other forms of C/E sensory loss (e.g., deafness) do not reduce the risk of schizophrenia. We conclude by discussing implications of these data for designing cognitive training interventions to reduce schizophrenia-related cognitive impairment, and perhaps to reduce the likelihood of the development of the disorder itself.

How can the brain's resting state activity generate hallucinations? A 'resting state hypothesis' of auditory verbal hallucinations

While several hypotheses about the neural mechanisms underlying auditory verbal hallucinations (AVH) have been suggested, the exact role of the recently highlighted intrinsic resting state activity of the brain remains unclear. Based on recent findings, we therefore developed what we call the 'resting state hypotheses' of AVH. Our hypothesis suggest that AVH may be traced back to abnormally elevated resting state activity in auditory cortex itself, abnormal modulation of the auditory cortex by anterior cortical midline regions as part of the default-mode network, and neural confusion between auditory cortical resting state changes and stimulus-induced activity. We discuss evidence in favour of our 'resting state hypothesis' and show its correspondence with phenomenological accounts.

A Lacanian perspective on psychotic hallucinations

This article gives an overview of the psychiatric approach to psychotic hallucinations and discusses Lacan’s conceptual break from this paradigm. Rejecting the traditional focus on the unreality of hallucinatory perceptions, Lacan examines the effects that psychotic hallucinations have on the person who experiences them. He develops an alternative theoretical framework which indicates that psychosis is characterized by the incapacity to signify one’s own existence as a subject in relation to the Other. Lacan’s different perspectives on hallucinations are discussed in terms of the logic of signification as the constitution of subjectivity and as a manifestation of the object a and jouissance, and also in terms of his theory of the sinthome.

Linguistic ability and mental health outcomes among deaf people with schizophrenia

Cognition has become prominent in the study of schizophrenia because of its importance for understanding the etiology of the illness and its consequences for living independently. For people with schizophrenia who are also deaf, investigations of cognition and schizophrenia are infrequent. This study examines the role of linguistic ability in relation to cognition, social cognition, and functional outcome among deaf adults with schizophrenia or schizoaffective disorder. The primary finding is that linguistic ability is positively and significantly associated with functional outcome above and beyond the contribution of cognition and social cognition. A younger age of sign language acquisition is significantly associated with superior linguistic ability, but did not moderate the effect of linguistic ability on other domains. Opportunities for deaf mental health consumers to participate in sign language enrichment programs and communicate with other skilled signers may be useful additions to standard psychiatric rehabilitation programming. More research is needed to clarify the consequences of deafness with regards to schizophrenia especially as it relates to language, vision, and symptoms.

Hallucinations in nonpsychotic disorders: toward a differential diagnosis of "hearing voices"

While auditory hallucinations (AH) are prototypic psychotic symptoms whose clinical presence is often equated with a psychotic disorder, they are commonly found among those without mental illness as well as those with nonpsychotic disorders not typically associated with hallucinations in DSM-IV. This incongruity presents a significant challenge for clinical work and efforts to revise the next iteration of the DSM. Auditory hallucinations found among "normal" people suggest that either AH are not as pathologic as they are typically taken to be, or that less-than-hallucinatory experiences are routinely mischaracterized as AH. Such hallucinations in the context of conversion disorder, trauma, sensory deprivation, and certain cultural settings strengthen an association between AH and psychopathology but suggest limited diagnostic specificity and relevance. It may be useful to think of AH like coughs-common experiences that are often, but not always, symptoms of pathology associated with a larger illness. Although these issues have been known for many years, they are rarely discussed in American psychiatry and need to be addressed in future research and clinical work.

Visual feedback and self-monitoring of sign language

The perceptual loop theory of self-monitoring posits that auditory speech output is parsed by the comprehension system. For sign language, however, visual input from one's own signing is distinct from visual input received from another's signing. Two experiments investigated the role of visual feedback in the production of American Sign Language (ASL). Experiment 1 revealed that signers were poor at recognizing ASL signs when viewed as they would appear during self-produced signing. Experiment 2 showed that the absence or blurring of visual feedback did not affect production performance when deaf signers learned to reproduce signs from Russian Sign Language, and production performance of hearing non-signers was slightly worse with visual feedback. Signers may rely primarily on somatosensory feedback when monitoring language output, and if the perceptual loop theory is to be maintained, the comprehension system must be able to parse a somatosensory signal as well as an external perceptual signal for both sign and speech.

Reality of auditory verbal hallucinations

Distortion of the sense of reality, actualized in delusions and hallucinations, is the key feature of psychosis but the underlying neuronal correlates remain largely unknown. We studied 11 highly functioning subjects with schizophrenia or schizoaffective disorder while they rated the reality of auditory verbal hallucinations (AVH) during functional magnetic resonance imaging (fMRI). The subjective reality of AVH correlated strongly and specifically with the hallucination-related activation strength of the inferior frontal gyri (IFG), including the Broca's language region. Furthermore, how real the hallucination that subjects experienced was depended on the hallucination-related coupling between the IFG, the ventral striatum, the auditory cortex, the right posterior temporal lobe, and the cingulate cortex. Our findings suggest that the subjective reality of AVH is related to motor mechanisms of speech comprehension, with contributions from sensory and salience-detection-related brain regions as well as circuitries related to self-monitoring and the experience of agency.

Exploring the perceptual characteristics of voice-hallucinations in deaf people

INTRODUCTION

Previous research has not taken account of the possibility that deaf people will show greater heterogeneity in how they experience voice-hallucinations due to individual differences in experience with language and residual hearing. This study aims to explore how deaf participants perceive voice-hallucinations and whether the perceptual characteristics reported reflect individual experience with language and sensory input.

METHOD

A statement-sorting task generated data about perceptual characteristics of voice-hallucinations for exploratory factor analysis. The sample included 27 deaf participants with experience of voice-hallucinations, and a range of hearing loss and language backgrounds.

RESULTS

Perceptual characteristics of voice-hallucinations map closely onto individual auditory experience. People born profoundly deaf loaded onto nonauditory factors. Deaf people with experience of hearing speech, through residual hearing, hearing aids, or predeafness experience, reported auditory features or uncertainty about mode of perception.

CONCLUSIONS

This is the first study to systematically explore voice-hallucinations in deaf people and to advance a model of subvocal articulation to account for such counterintuitive phenomena.