Diagnostic criteria in schizophrenia: accentuate the positive.
(57/533)
In a recent article, Andreasen and Flaum (Schizophrenia Bulletin, Vol. 17, No. 1, 1991) argued that greater emphasis should be placed on negative symptoms in the diagnosis of schizophrenia, leading to a less important role for positive symptoms. This article presents a counter-argument to this view. Positive symptoms are common and reliable and therefore highly useful diagnostically. First-rank symptoms, although not specific to schizophrenia, show good discriminability. No other type of symptom or investigative method can make such claims to usefulness. Although positive symptoms do not predict outcome, this is not a necessary function of diagnostic criteria. The predictive power of negative symptoms is, in any case, based largely on studies of patients with chronic disorder. Premorbidly impaired social development may interact with schizophrenia, worsening the prognosis. We believe positive symptoms have always been the essence of psychiatric disorder and should remain so. Increasing the diagnostic weight given to negative symptoms risks restricting the definition of schizophrenia excessively. (+info)
Auditory hallucinations, source monitoring, and the belief that "voices" are real.
(58/533)
The term source monitoring refers to a variety of cognitive processes individuals use to determine whether an experience originated within the self or came from an external source. A belief that auditory hallucinations are real entities independent of the self may be considered an error in source monitoring. The Source Monitoring Framework (SMF) is the most developed and empirically validated model of how ordinary individuals judge whether an event was self-generated or occurred in the outside world. This study of 41 acute inpatients is a first attempt to apply the SMF to autobiographical reports of auditory hallucinations in a clinical setting. Consistent with the SMF, results suggest that similarities between "voices" and real speakers may offer a partial explanation of why patients believe the voices are real. While the SMF provides a useful conceptual background for examining the phenomenology of these voices, the types of source monitoring errors typically encountered in normal individuals do not fully account for this belief as it occurs in psychotic individuals. (+info)
Brain modules of hallucination: an analysis of multiple patients with brain lesions.
(59/533)
We systematically reviewed the localization of focal brain lesions that cause isolated hallucination in a single sensory modality. Case reports of post-lesion nonparoxysmal hallucination in 1 (and only 1) of 3 sensory modalities (i.e., visual, auditory, somatic) were reviewed, and the content of the qualitative descriptions was analyzed for each modality. The lesion is practically always located in the brain pathway of the sensory modality of the hallucination. There seem to exist localized sensory brain circuits that in healthy people diminish the intensity of internal sensory representation. After a lesion, hallucinosis seems to be caused also by compensatory overactivation of tissue in the nearby brain sensory pathway. This type of hallucination may indeed be termed a "release" form, whereby patients are aware of the hallucinatory nature of their experience, but not usually of "dream centres" as proposed by Lhermitte. Instead, we propose that it is dreaming that should be considered a special case of neural "release." (+info)
Neuroanatomy of "hearing voices": a frontotemporal brain structural abnormality associated with auditory hallucinations in schizophrenia.
(60/533)
Auditory hallucinations are a frequent symptom in schizophrenia. While functional imaging studies have suggested the association of certain patterns of brain activity with sub-syndromes or single symptoms (e.g. positive symptoms such as hallucinations), there has been only limited evidence from structural imaging or post-mortem studies. In this study, we investigated the relation of local brain structural deficits to severity of auditory hallucinations, particularly in perisylvian areas previously reported to be involved in auditory hallucinations. In order to overcome certain limitations of conventional volumetric methods, we used deformation-based morphometry (DBM), a novel automated whole-brain morphometric technique, to assess local gray and white matter deficits in structural magnetic resonance images of 85 schizophrenia patients. We found severity of auditory hallucinations to be significantly correlated (P < 0.001) with volume loss in the left transverse temporal gyrus of Heschl (primary auditory cortex) and left (inferior) supramarginal gyrus, as well as middle/inferior right prefrontal gyri. This demonstrates a pattern of distributed structural abnormalities specific for auditory hallucinations and suggests hallucination-specific alterations in areas of a frontotemporal network for processing auditory information and language. (+info)
Out-of-body experience and autoscopy of neurological origin.
(61/533)
During an out-of-body experience (OBE), the experient seems to be awake and to see his body and the world from a location outside the physical body. A closely related experience is autoscopy (AS), which is characterized by the experience of seeing one's body in extrapersonal space. Yet, despite great public interest and many case studies, systematic neurological studies of OBE and AS are extremely rare and, to date, no testable neuroscientific theory exists. The present study describes phenomenological, neuropsychological and neuroimaging correlates of OBE and AS in six neurological patients. We provide neurological evidence that both experiences share important central mechanisms. We show that OBE and AS are frequently associated with pathological sensations of position, movement and perceived completeness of one's own body. These include vestibular sensations (such as floating, flying, elevation and rotation), visual body-part illusions (such as the illusory shortening, transformation or movement of an extremity) and the experience of seeing one's body only partially during an OBE or AS. We also find that the patient's body position prior to the experience influences OBE and AS. Finally, in five patients, brain damage or brain dysfunction is localized to the temporo-parietal junction (TPJ). These results suggest that the complex experiences of OBE and AS represent paroxysmal disorders of body perception and cognition (or body schema). The processes of body perception and cognition, and the unconscious creation of central representation(s) of one's own body based on proprioceptive, tactile, visual and vestibular information-as well as their integration with sensory information of extrapersonal space-is a prerequisite for rapid and effective action with our surroundings. Based on our findings, we speculate that ambiguous input from these different sensory systems is an important mechanism of OBE and AS, and thus the intriguing experience of seeing one's body in a position that does not coincide with its felt position. We suggest that OBE and AS are related to a failure to integrate proprioceptive, tactile and visual information with respect to one's own body (disintegration in personal space) and by a vestibular dysfunction leading to an additional disintegration between personal (vestibular) space and extrapersonal (visual) space. We argue that both disintegrations (personal; personal-extrapersonal) are necessary for the occurrence of OBE and AS, and that they are due to a paroxysmal cerebral dysfunction of the TPJ in a state of partially and briefly impaired consciousness. (+info)
Transient musical hallucinosis of central origin: a review and clinical study.
(62/533)
A 52 year old, right handed, hearing impaired woman was admitted with headache and neck stiffness. The only neuropsychological symptom was transient auditory perceptions in the left ear, which were musical, seemed familiar and were not influenced by verbal communication. CT and MRI showed a right subarachnoid haemorrhage, while brainstem auditory evoked potentials failed to reveal a brainstem lesion. In patients with organic cerebral disease, unilateral auditory hallucinations (AHs) may indicate a lesion in the contralateral hemisphere. However, according to this review the type of AHs (verbal versus musical) is not consistently associated with a cerebral lesion on either side. (+info)
Visual command hallucinations in a patient with pure alexia.
(63/533)
Around 25% of patients with visual hallucinations secondary to eye disease report hallucinations of text. The hallucinated text conveys little if any meaning, typically consisting of individual letters, words, or nonsense letter strings (orthographic hallucinations). A patient is described with textual visual hallucinations of a very different linguistic content following bilateral occipito-temporal infarcts. The hallucinations consisted of grammatically correct, meaningful written sentences or phrases, often in the second person and with a threatening and command-like nature (syntacto-semantic visual hallucinations). A detailed phenomenological interview and visual psychophysical testing were undertaken. The patient showed a classical ventral occipito-temporal syndrome with achromatopsia, prosopagnosia, and associative visual agnosia. Of particular significance was the presence of pure alexia. Illusions of colour induced by monochromatic gratings and a novel motion-direction illusion were also observed, both consistent with the residual capacities of the patient's spared visual cortex. The content of orthographic visual hallucinations matches the known specialisations of an area in the left posterior fusiform gyrus--the visual word form area (VWFA)--suggesting the two are related. The VWFA is unlikely to be responsible for the syntacto-semantic hallucinations described here as the patient had a pure alexic syndrome, a known consequence of VWFA lesions. Syntacto-semantic visual hallucinations may represent a separate category of textual hallucinations related to the cortical network implicated in the auditory hallucinations of schizophrenia. (+info)
The addition of intravenous caffeine during an amobarbital interview.
(64/533)
Although the amobarbital interview is an effective means of temporarily relieving catatonic mutism, some catatonic patients simply fall asleep during an amobarbital interview. We are examining the feasibility of administering intravenous caffeine benzoate during an amobarbital interview to prevent patients from falling asleep. This paper describes an open trial of the administration of 500 mg caffeine benzoate during amobarbital interviews with ten patients. The procedure was well tolerated, but further studies are needed to determine whether or not caffeine is an advantage over amobarbital alone. (+info)