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PubMed2002

Altered performance of schizophrenia patients in an auditory detection and discrimination task: exploring the 'self-monitoring' model of hallucination.

It has been suggested that perceptual hallucination results from a bias in attributing a self-generated event to an external source. The 'self-monitoring' model proposes that the impairment arises from a defective corollary discharge in perceptual decisions. However, psychophysical studies in schizophrenia patients have not found consistent support for the model. We re-explored this issue by including subjects with mood disorders as patient controls and employed signals of variable intensities in an auditory detection and discrimination task. Using signal detection theory, we found decreased sensitivity in auditory detection and discrimination in schizophrenia patients, as compared to control subjects. Moreover, the psychometric functions of schizophrenics had a shallower slope than those of the controls. According to the uncertainty theory of signal detection, this suggested that schizophrenia patients monitored a smaller number of perceptual channels. On the other hand, hallucinating and non-hallucinating schizophrenia patients did not differ from each other, nor did they as a group differ from control subjects in terms of response bias. Overall, our results do not support the idea that hallucination results from an altered bias in the online processing of perceptual signals.

Adult↗
PubMed1999

The CCK-A receptor gene possibly associated with auditory hallucinations in schizophrenia.

In this study, a PstI polymorphic site with two individual alleles, namely A1 and A2, was identified withinthe boundary between intron 1 and exon 2 of the cholecystokinin (CCK) type A receptor gene. The PstI polymorphic site was used as a genetic marker to study its association with psychotic symptoms in schizophrenia. A significant difference in allelic frequency was found between schizophrenic patients with and without auditory hallucinations(chi(2) = 6.26, df = 1, P = 0.012), and the odds ratio for the allelic association was 2.21 (95% CI 1.18-4.15) with an attributable fraction of 0.1. The frequency of A1-A1 and A1-A2 genotypes showed a significant excess in schizophrenic patients with auditory hallucinations as compared to those without such symptoms (chi(2) = 5.45, df = 1, P = 0.02), and the odds ratio for the genotypic association was 2.27 (95% CI 1. 13-4.57) with an attributable fraction of 0.177. The haplotype-based haplotype relative risk (HHRR) test revealed a significant difference between transmitted and non-transmitted alleles in nuclear families of schizophrenic patients with auditory hallucinations (chi(2) = 4.54, df = 1,P = 0.033) but not in those of schizophrenic patients without them. The present study suggests that the CCK-A receptor gene may be associated with auditory hallucinations in schizophrenia.

Adult↗
PubMed1984

Hallucinations in children with conduct and emotional disorders: II. The follow-up study.

In a controlled study, 20 children with hallucinations and emotional or conduct disorders were followed up into adulthood. The mean follow-up time was 17 years and the mean age at follow-up was 30 years. Hallucinations in childhood did not carry an increased risk for psychoses, depressive illness, organic brain damage or other psychiatric disorders. The continuation of hallucinations and episodes of altered awareness in some of the subjects may indicate a special predisposition to hallucinate.

Adolescent↗
PubMed1997

What voices can do with words: pragmatics of verbal hallucinations.

BACKGROUND: In this paper we consider verbal hallucinations as inner speech with pragmatics. The specific pragmatic properties of verbal hallucinations investigated included the number of voices, the characteristics that individuate the voices, the sequential characteristics of the dialogues between voice hearers and their voices, the dialogical positioning of voices hearers, voices and other individuals, and how the voices influence voice hearers' activities. METHODS: These properties were examined in structured interviews with 28 individuals, 14 of whom had a diagnosis of schizophrenia, while 14 were students who did not use psychiatric services. RESULTS: The analysis showed that voices were most frequently individuated with reference to individuals significant to voice hearers. The talk with voices was typically mundane and related to voice hearers' on-going activities, as is the case for ordinary inner speech. The voices were typically orientated towards the voice hearer, without direct access to each other or to other people. Contrary to received wisdom, the voices typically did not impel actions of voice hearers, rather they influenced voice hearers' decisions on how to act. This was so irrespective of the diagnostic status of informants. Finally, we have found some differences between the voices of informants with, and without, schizophrenia. These concerned the alignment of voices, the type of action required by a voice and the degree of dialogical engagement between voices and voice hearers. CONCLUSIONS: We conclude that verbal hallucinations can be fruitfully considered to be a genus of inner speech. Pragmatics can be used as a framework to distinguish verbal hallucinations in different populations.

Adult↗
PubMed2000

The perception of self-produced sensory stimuli in patients with auditory hallucinations and passivity experiences: evidence for a breakdown in self-monitoring.

BACKGROUND: To test the hypothesis that certain psychotic symptomatology is due to a defect in self-monitoring, we investigated the ability of groups of psychiatric patients to differentiate perceptually between self-produced and externally produced tactile stimuli. METHODS: Responses to tactile stimulation were assessed in three groups of subjects: schizophrenic patients; patients with bipolar affective disorder or depression; and normal control subjects. Within the psychiatric groups subjects were divided on the basis of the presence or absence of auditory hallucinations and/or passivity experiences. The subjects were asked to rate the perception of a tactile sensation on the palm of their left hand. The tactile stimulation was either self-produced by movement of the subject's right hand or externally produced by the experimenter. RESULTS: Normal control subjects and those psychiatric patients with neither auditory hallucinations nor passivity phenomena experienced self-produced stimuli as less intense, tickly and pleasant than identical, externally produced tactile stimuli. In contrast, psychiatric patients with these symptoms did not show a decrease in their perceptual ratings for tactile stimuli produced by themselves as compared with those produced by the experimenter. This failure to show a difference in perception between self-produced and externally produced stimuli appears to relate to the presence of auditory hallucinations and/or passivity experiences rather than to the diagnosis of schizophrenia. CONCLUSIONS: We propose that auditory hallucinations and passivity experiences are associated with an abnormality in the self-monitoring mechanism that normally allows us to distinguish self-produced from externally produced sensations.

Adult↗
PubMed2004

Hallucinations in schizophrenia, sensory impairment, and brain disease: a unifying model.

Based on recent insight into the thalamocortical system and its role in perception and conscious experience, a unified pathophysiological framework for hallucinations in neurological and psychiatric conditions is proposed, which integrates previously unrelated neurobiological and psychological findings. Gamma-frequency rhythms of discharge activity from thalamic and cortical neurons are facilitated by cholinergic arousal and resonate in networks of thalamocortical circuits, thereby transiently forming assemblies of coherent gamma oscillations under constraints of afferent sensory input and prefrontal attentional mechanisms. If perception is based on synchronisation of intrinsic gamma activity in the thalamocortical system, then sensory input to specific thalamic nuclei may merely play a constraining role. Hallucinations can be regarded as underconstrained perceptions that arise when the impact of sensory input on activation of thalamocortical circuits and synchronisation of thalamocortical gamma activity is reduced. In conditions that are accompanied by hallucinations, factors such as cortical hyperexcitability, cortical attentional mechanisms, hyperarousal, increased noise in specific thalamic nuclei, and random sensory input to specific thalamic nuclei may, to a varying degree, contribute to underconstrained activation of thalamocortical circuits. The reticular thalamic nucleus plays an important role in suppressing random activity of relay cells in specific thalamic nuclei, and its dysfunction may be implicated in the biological vulnerability to hallucinations in schizophrenia. Combined with general activation during cholinergic arousal, this leads to excessive disinhibition in specific thalamic nuclei, which may allow cortical attentional mechanisms to recruit thalamic relay cells into resonant assemblies of gamma oscillations, regardless of their actual sensory input, thereby producing an underconstrained perceptual experience.

Arousal↗
PubMed2001

Musical hallucinations associated with abruptly developed bilateral loss of hearing.

OBJECTIVE: To present a depressive patient who developed abrupt hearing loss with musical hallucinations. METHOD: This study is a case report. The patient was evaluated by cranial CT, EEG. audiometry, brain SPECT. MMPI and the Hamilton Depression Scale. RESULTS: A patient with depression developed abrupt hearing loss with musical hallucinations following an intramuscular injection of gentamycin. Audiometry showed mild sensorineural hearing loss in both ears. The Hamilton Depression Scale disclosed moderate depression. Her symptoms disappeared with the initiation of antidepressive medication. CONCLUSION: Musical hallucinations are the hearing of tunes, melodies, harmonics, rhythms and timbres. They have been reported to be in association with healing loss in several published cases. The uniqueness of our patient was that she was younger than previously reported cases of musical hallucinations, who were elderly people, and her symptoms of depression disappeared gradually after the initiation of moclobemide.

Adult↗
PubMed2005

Hallucinations, negative symptoms, and response bias in a verbal recognition task in schizophrenia.

Several studies have reported an association between hallucinations and tendency to make false alarms in acoustic signal detection tasks. Previous work on patients with schizophrenia has suggested that false recognitions and other types of memory error were positively associated with hallucinations and inversely associated with certain negative symptoms of withdrawal. In this study, 40 patients with schizophrenia were administered a word recognition task. Mixed lists of high- and low-frequency words were presented, then the target words had to be recognized among distractors in immediate and delayed recognition conditions. Hallucination scores were correlated with an increased bias toward false recognitions of nonpresented words. Affective flattening tended to be correlated with a reduced bias toward false recognitions. Anhedonia was significantly correlated with a reduced response bias. Hallucinations and anhedonia therefore presented an opposite association with the response bias. The influence of word frequency and delay on this association is discussed.

Adult↗
PubMed1998

The anatomy of conscious vision: an fMRI study of visual hallucinations.

Despite recent advances in functional neuroimaging, the apparently simple question of how and where we see--the neurobiology of visual consciousness--continues to challenge neuroscientists. Without a method to differentiate neural processing specific to consciousness from unconscious afferent sensory signals, the issue has been difficult to resolve experimentally. Here we use functional magnetic resonance imaging (fMRI) to study patients with the Charles Bonnet syndrome, for whom visual perception and sensory input have become dissociated. We found that hallucinations of color, faces, textures and objects correlate with cerebral activity in ventral extrastriate visual cortex, that the content of the hallucinations reflects the functional specializations of the region and that patients who hallucinate have increased ventral extrastriate activity, which persists between hallucinations.

Brain Mapping↗
PubMed2004

Relevance of sleep paralysis and hypnic hallucinations to psychiatry.

OBJECTIVE: To describe a patient who presented with psychopathology in the wake of sleep paralysis and hypnopompic hallucinations, and to discuss the importance of these phenomena to psychiatric diagnoses. METHODS: Case report. RESULTS: A 25-year-old black South African woman developed paranoid beliefs and a sad and anxious mood in the wake of her first experience of sleep paralysis and hypnic hallucinations. She had no history of other sleep-related events. Reassurance, explanation of the physiological basis of her experience, and a short course of low-dose diazepam were provided. Her mood and sleep improved promptly and she no longer held paranoid beliefs. She did not experience further episodes of sleep paralysis or hypnic hallucinations and improvement was sustained at 6 months. CONCLUSIONS: It pays to probe for the core experiences or events that patients may be explaining by devising "delusions". Acute, nocturnal-onset, first-time psychopathology warrants inquiry for sleep paralysis and hypnic hallucinations. Sleep-related side-effects of psychotropic medications need to be studied more closely.

Adult↗
PubMed2003

Phenomenology of hallucinations: a factor analytic approach.

The present study was carried out with the aim of obtaining a factor analytic solution of parameters of hallucinations in schizophrenia. Seventy-five chronic hallucinating schizophrenic patients were assessed on the Phenomenology of Hallucinations Scale and Brief Psychiatric Rating Scale. A factor analytic solution was obtained by principal component analysis using varimax rotation. Two factors, 'reality of hallucinatory perception' and 'immersion in hallucination', were obtained. Findings are discussed in relation to existing literature.

Adult↗
PubMed2002

Complex hallucinations following occipital lobe damage.

Visual hallucinations may accompany many neurological and psychiatric disorders. A common localization principle is that lesions to the early sensory cortices lead to elementary hallucinations, whereas complex perceptual experiences are related to the pathology of higher-level cortical regions. We report the case of a patient who experienced complex, non-stereotyped, multimodal (visual and somatosensory) hallucinations following an acute ischaemic vascular lesion in the right medial occipital lobe. This illustrates that the phenomenology of hallucinations not necessarily reflects the exact localization of cerebral pathology. Instead, the damaged area may serve as a focus of an abnormally activated neuronal network.

Aged↗
PubMedDate not supplied

Olfactory hallucinations during migraine in an adolescent with an MRI temporal lobe lesion.

OBJECTIVE: To report the first example of an abnormal magnetic resonance imaging (MRI) test in a patient with migraine and olfactory hallucinations and to provide additional evidence for a possible role of the temporal lobe in migraine. BACKGROUND: The relationship between the temporal lobe and migraine with or without hallucinations is unclear and continues to evolve. Clinical and functional neuroimaging studies (positron emission tomography/single photon emission computed tomography) have lent support to the possibility of a relationship. Anatomical neuroimaging with computed tomography has previously been normal. METHODS: The history and findings of an adolescent with migraine and olfactory hallucinations is reported. RESULTS: Brain MRI demonstrated a mass in the temporal lobe. CONCLUSIONS: Magnetic resonance imaging should be considered in patients with olfactory hallucinations and migraine. In addition, the role of the temporal lobe in migraine warrants further study.

Adolescent↗
PubMed1998

[Hallucinations of body magnification in migraine].

Hallucinations of body magnification, representing aura symptoms of migraine, are recorded in 2 original observations and in 32 cases reported in the clinical literature. These hallucinations represent an isolated neuropsychological symptom that can be conceived as a disorder of the body schema. The head and the hands are the anatomic regions that are most frequently affected. This parallels the dominance of representation of these regions in the sensory cerebral cortex. Hallucinations of body magnification frequently co-occur with aura symptoms of basilar migraine, which is compatible with the hypothesis of a localisation of these hallucinations in the regions of the thalamus and the parieto-temporo-occipital cortex.

Adult↗
PubMed1993

[Olfactory hallucinations in depression].

Olfactory hallucinations are rarely mentioned as a symptom of depressive disorder. This paper presents a review of the literature including a conceptual clarification and epidemiological aspects with an emphasis on the significance of olfactory hallucinations for psychopathology, in particular with respect to sensory perception and body self-awareness. The close relation to the olfactory reference syndrome is pointed at. Olfactory hallucinations are considered important for the biological interpretation of affective disorders. In this regard disturbed olfactory perception can be understood as an example of disturbed brain function in the state of depression. Olfactory symptoms are shown to be elements connecting primary affective disorders with other neuropsychiatric diseases as well as with neuroanatomical and neurophysiological models. A primary role is accordingly attributed to the temporal lobe epilepsies in which olfactory hallucinations as well as affective disturbances occur. The need for further investigation in this field is pointed out.

Brain↗
PubMed1999

[Visual hallucinations and illusions, symptoms frequently misdiagnosed by the practitioner].

INTRODUCTION: Visual hallucinations or illusions are not a rare symptom. However, they are often unrecognized. Unawareness of the meaning of these symptoms often mislead both the patient and his physician. PURPOSE: To define and describe the types of visual illusions and hallucinations which can be commonly encountered in neuro-ophthalmological practice. METHODS: Overview article. RESULTS: Hallucinations are a perception not based on sensory input, whereas illusions are a misinterpretation of a correct sensory input. Both phenomenon can be due to medication or drug, or to an altered mental status. Visual hallucinations can be formed (objects, people) or unformed (light, geometric figures). They can be generated either by a lesion on the antechiasmatic pathway, by a seizure phenomenon, by a migrainous phenomenon, or by a release phenomenon secondary to visual differentiation. Investigations will be directed towards a retinopathy, an optic neuropathy, a chiasmal or retrochiasmal lesion, or a bilateral antechiasmal lesion (Charles Bonnet syndrome). Visual illusions include meta-morphopsias, micro- macropsias, polyopia, palinopsia (visual perseveration), achromatopsia, Pulfrich phenomenon, or subjective vertical deviation. Illusions can be due to lesions of the retina, the optic nerve, the visual cortex (primary or associative), or the graviceptive pathways. CONCLUSIONS: As most patients do not spontaneously mention their symptoms, history taking is essential. The first step is to rule out medication or an altered mental status as the possible cause of these symptoms. Then, careful visual function examination should provide a good insight in the location of the lesion.

Diagnosis, Differential↗
PubMed2006

Mr morphometry analysis of grey matter volume reduction in schizophrenia: association with hallucinations.

The authors used voxel-based morphometry (VBM) to study GM volume differences in the whole brain volume between a group of patients with schizophrenia and a healthy control group. There were 12 patients and 12 control subjects. The subjects were scanned in a 1.5 T MR scanner. The patients had all been evaluated by a senior psychiatrist on the brief psychiatric rating scale (BPRS). The VBM data was correlated with reports of rate and frequency of hallucinations based on their scores on the BPRS hallucination item. There were significant grey matter volume reductions in the schizophrenia patient group in the left superior (transverse) temporal gyrus, the left middle frontal gyrus, and in the right cuneus. Areas of grey matter volume reduction that correlated negatively with hallucinations were found in the left superior (transverse) temporal gyrus, left thalamus, and left and right cerebellum. This article proposes that significant reductions in grey matter volume may be instrumental in generating spontaneous neuronal activity that is associated with speech perception experiences in the absence of an external acoustic stimulus that may cause hallucinations.

Adult↗
PubMed2006

The treatment of recurring auditory hallucinations in schizophrenia with rTMS.

BACKGROUND: Auditory hallucinations are a common and disabling problem for many patients with schizophrenia and often fail to respond to optimal antipsychotic therapy. Repetitive transcranial magnetic stimulation (rTMS) has recently been trialled as an alternative treatment option for these patients. These studies have generally been positive, but treatment has only been provided for short periods of time and little is known about the longer-term impact of TMS on the course of hallucinations. METHOD: We describe two cases in which rTMS was provided to patients upon relapse of hallucinations following initial successful rTMS treatment in a clinical trial. RESULTS: A repeat course of rTMS resulted in a marked improvement in the symptoms experienced by these two patients. CONCLUSIONS: rTMS appears to have potential as a long-term treatment for patients with auditory hallucinations, but requires ongoing systematic investigation.

Adolescent↗