969 resultados para Hallucinations and illusions.


Relevância:

30.00% 30.00%

Publicador:

Resumo:

This study is part of the joint project "The Genetic Epidemiology and Molecular Genetics of schizophrenia in Finland" between the Departments of Mental Health and Alcohol Research, and Molecular Medicine at the National Public Health Institute. In the study, we utilized three nationwide health care registers: 1) the Hospital Discharge Register, 2) the Free Medication Register, and 3) the Disability Pension Register, plus the National Population Register, in order to identify all patients with schizophrenia born from 1940 to 1976 (N=33,731) in Finland, and their first degree-relatives. 658 patients with at least one parent born in a homogeneous isolate in northeastern Finland were identified, as well as 4904 familial schizophrenia patients with at least two affected siblings from the whole country. The comparison group was derived from the Health 2000 Study. We collected case records and reassessed the register diagnosis. Were contacted the isolate patients and a random sample of patients from the whole country to make diagnostic clinical interviews and to assess the negative and positive symptoms and signs of schizophrenia. In addition to these patients, we interviewed siblings who were initially healthy according to the Hospital Discharge Register. Of those with a register diagnosis of schizophrenia, schizoaffective or schizophreniform disorder, 69% received a record-based consensus diagnosis and 63% an interview-based diagnosis of schizophrenia. Patients with schizophrenia having first-degree relatives with psychotic disorder had more severe affective flattening and alogia than those who were the only affected individuals in their family. The novel findings were: 1) The prevalence of schizophrenia in the isolate was relatively high based on register (1.5%), case record (0.9-1.3%), and interview (0.7-1.2%) data. 2) Isolate patients, regardless of their familial loading for schizophrenia, had less delusions and hallucinations than the whole country familial patients, which may be related to the genetic homogeneity in the isolate. This phenotype encourages the use of endophenotypes in genetic analyses instead of diagnoses alone. 3) The absence of register diagnosis does not confirm that siblings are healthy, because 7.7% of siblings had psychotic symptoms already before the register diagnoses were identified in 1991. For genetic research, the register diagnosis should therefore be reassessed using either a structured interview or a best- estimate case note consensus diagnosis. Structured clinical interview methods need be considered also in clinical practice.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

We wished to replicate evidence that an experimental paradigm of speech illusions is associated with psychotic experiences. Fifty-four patients with a first episode of psychosis (FEP) and 150 healthy subjects were examined in an experimental paradigm assessing the presence of speech illusion in neutral white noise. Socio-demographic, cognitive function and family history data were collected. The Positive and Negative Syndrome Scale (PANSS) was administered in the patient group and the Structured Interview for Schizotypy-Revised (SIS-R), and the Community Assessment of Psychic Experiences (CAPE) in the control group. Patients had a much higher rate of speech illusions (33.3% versus 8.7%, ORadjusted: 5.1, 95% CI: 2.3-11.5), which was only partly explained by differences in IQ (ORadjusted: 3.4, 95% CI: 1.4-8.3). Differences were particularly marked for signals in random noise that were perceived as affectively salient (ORadjusted: 9.7, 95% CI: 1.8-53.9). Speech illusion tended to be associated with positive symptoms in patients (ORadjusted: 3.3, 95% CI: 0.9-11.6), particularly affectively salient illusions (ORadjusted: 8.3, 95% CI: 0.7-100.3). In controls, speech illusions were not associated with positive schizotypy (ORadjusted: 1.1, 95% CI: 0.3-3.4) or self-reported psychotic experiences (ORadjusted: 1.4, 95% CI: 0.4-4.6). Experimental paradigms indexing the tendency to detect affectively salient signals in noise may be used to identify liability to psychosis.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

A neural network model of early visual processing offers an explanation of brightness effects often associated with illusory contours. Top-down feedback from the model's analog of visual cortical complex cells to model lateral geniculate nucleus (LGN) cells are used to enhance contrast at line ends and other areas of boundary discontinuity. The result is an increase in perceived brightness outside a dark line end, akin to what Kennedy (1979) termed "brightness buttons" in his analysis of visual illusions. When several lines form a suitable configuration, as in an Ehrenstein pattern, the perceptual effect of enhanced brightness can be quite strong. Model simulations show the generation of brightness buttons. With the LGN model circuitry embedded in a larger model of preattentive vision, simulations using complex inputs show the interaction of the brightness buttons with real and illusory contours.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Recent growth in the shape-from-shading psychophysics literature has been paralled by an increasing availability of computer graphics hardware and software, to the extent that most psychophysical studies in this area now employ computer lighting algorithms. The most widely used of algorithms is shape-from-shading psychophysics is the Phong lighting model. This model, and other shading models of its genre, produce readily ineterpretable imiages of three-dimensional scenes. However, such algorithms are only approximations of how light interacts with real objects in the natural environment. Nevertheless, the results from psychophysical experiments using these techniques have been used to infer the processes underlying the perception of shape-from-shading in natural environments. It is important to establish whether this substitution is ever valid. We report a series of experiments investigating whether two recently reported illusions seen computer-generated, Phond shaded images occur for solid objects under real illuminants. The two illusions investigated are three-dimensional curvature contrast and the illuminant-position effect on perceived curvature. We show that both effects do occur for solid objects, and that the magnitude of these effects are equivalent regardless of whether subjects are presented with ray traced or solid objects.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The article retraces the career of the famous hypnotist Onofroff and particularly his visit to Buenos Aires, where his activity, in 1895, provoked many discussions and some public embarrassment. In this context Darío, using a pseudonym, published his crónica “La esfinge”. We reproduce “La esfinge”, transcribing the original text of La Nación, with annotations identifying the literary and theosophical sources Darío used when he wrote it.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

We tested four genes [phenylalanine hydroxylase (PAH), the serotonin transporter (SLC6A4), monoamine oxidase B (MAOB), and the gamma-aminobutyric acid A receptor beta-3 subunit (GABRB3)] for their impact on five schizophrenia symptom factors: delusions, hallucinations, mania, depression, and negative symptoms. In a 90 family subset of the Irish Study of High Density Schizophrenia Families, the PAH 232 bp microsatellite allele demonstrated significant association with the delusions factor using both QTDT (F = 8.0, p = .031) and QPDTPHASE (chi-square = 12.54, p = .028). Also, a significant association between the GABRB3 191 bp allele and the hallucinations factor was detected using QPDTPHASE (chi-square 15.51, p = .030), but not QTDT (chi-square = 2.07, p = .560). (C) 2009 Elsevier B.V. All rights reserved.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

One of the enduring illusions about Northern Ireland is that its society can be conceptualized through a binary distinction between protestant and catholic. unionist and nationalist. It is increasingly apparent that these broad domains are themselves fractured and diverse and that otherness is often conceived from within rather than without. Northern Ireland can also be viewed as a laboratory for identity formation as unionists and loyalists strive to reconcile themselves with the fundamental political changes that have followed in the wake of the Peace Process. This paper considers one aspect of the contestation of belonging that increasingly characterizes unionism. It examines the competition for the ownership of the mythology of the Battle of the Somme ( 1916), long a key event in the unionist narrative. In particular, the paper addresses the ways in which paramilitary organizations are using the Somme to legitimate their own activities but also to distance the loyalist working classes from the former hegemonic Britishness of official unionism and the sectarianism of the Orange Order. The analysis concludes that loyalist identity is being conceptualized thorough a narrative of betrayal from within and at an intensely localized scale.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Following on from a quantitative study, this research used a qualitative methodology to investigate the lived experience of 3 men with chronic posttraumatic stress disorder associated with the conflict in Northern Ireland who reported auditory hallucinations. Data analysis used the Framework method. Results showed that beliefs about voices, dissociation of identity and body, and interpersonal impact were central superordinate themes associated with auditory hallucinations in posttraumatic stress disorder. Central subordinate themes included feeling a lack of controllability over voices, experiencing them as ego-dystonic, and feeling an increased sense of isolation and shame because of their presence. Results provide an in-depth analysis of participants' lived experiences and enhance understanding of previous quantitative findings.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

A functional polymorphism (Val-158-Met) at the Catechol-O-methyltransferase (COMT) locus has been identified as a potential etiological factor in schizophrenia. Yet the association has not been convincingly replicated across independent samples. We hypothesized that phenotypic heterogeneity might be diluting the COMT effect. To clarify the putative association, we performed an exploratory analysis to test for association between COMT and five psychosis symptom scales. These were derived through factor analysis of the Operational Criteria Checklist for Psychiatric Illness. Our sample was the Irish Study of High Density Schizophrenia Families, a large collection consisting of 268 multiplex families. This sample has previously shown a small but significant effect of the COMT Val allele in conferring risk for schizophrenia. We tested for preferential transmission of COMT alleles from parent to affected offspring (n = 749) for each of the five factor-derived scales (negative symptoms, delusions, hallucinations, mania, and depression). Significant overtransmission of the Val allele was found for mania (P <0.05) and depression (P = 0.01) scales. Examination of odds ratios (ORs) revealed a heterogeneous effect of COMT, whereby it had no effect on Negative Symptoms, but largest impact on Depression (OR = 1.4). These results suggest a modest affective vulnerability conferred by this allele in psychosis, but will require replication.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The comparator account holds that processes of motor prediction contribute to the sense of agency by attenuating incoming sensory information and that disruptions to this process contribute to misattributions of agency in schizophrenia. Over the last 25 years this simple and powerful model has gained widespread support not only as it relates to bodily actions but also as an account of misattributions of agency for inner speech, potentially explaining the etiology of auditory verbal hallucination (AVH). In this paper we provide a detailed analysis of the traditional comparator account for inner speech, pointing out serious problems with the specification of inner speech on which it is based and highlighting inconsistencies in the interpretation of the electrophysiological evidence commonly cited in its favor. In light of these analyses we propose a new comparator account of misattributed inner speech. The new account follows leading models of motor imagery in proposing that inner speech is not attenuated by motor prediction, but rather derived directly from it. We describe how failures of motor prediction would therefore directly affect the phenomenology of inner speech and trigger a mismatch in the comparison between motor prediction and motor intention, contributing to abnormal feelings of agency. We argue that the new account fits with the emerging phenomenological evidence that AVHs are both distinct from ordinary inner speech and heterogeneous. Finally, we explore the possibility that the new comparator account may extend to explain disruptions across a range of imagistic modalities, and outline avenues for future research.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Objective: The study aims to investigate associations between behavioural and psychological symptoms of dementia (BPSD) and abnormal premorbid personality traits. Methods: Data were obtained from 217 patients with a diagnosis of probable Alzheimer’s disease. Behavioural and psychological symptoms of late-onset dementia were assessed with the Neuropsychiatric Inventory. Premorbid personality traits were assessed using the Standardised Assessment of Personality. Abnormal premorbid personality traits were categorised with Diagnostic and Statistical Manual of Mental Disorders fourth edition and International Statistical Classification of Diseases and Related Health Problems—10 diagnostic criteria for personality disorders. Results: Abnormal premorbid personality traits were associated with increased behavioural and psychological symptoms in dementia. Cluster A (solitary/paranoid) premorbid personality traits were associated with anxiety, depression and hallucinations. Cluster C (anxious/dependent) traits were associated with a syndrome of depression. Conclusions: The presence of Clusters A (solitary/paranoid) and C (anxious/dependent) abnormal premorbid personality traits seems to affect the expression of certain behavioural and psychological symptoms in dementia, depression in particular. Copyright # 2016 John Wiley & Sons, Ltd

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Normal visual perception requires differentiating foreground from background objects. Differences in physical attributes sometimes determine this relationship. Often such differences must instead be inferred, as when two objects or their parts have the same luminance. Modal completion refers to such perceptual "filling-in" of object borders that are accompanied by concurrent brightness enhancement, in turn termed illusory contours (ICs). Amodal completion is filling-in without concurrent brightness enhancement. Presently there are controversies regarding whether both completion processes use a common neural mechanism and whether perceptual filling-in is a bottom-up, feedforward process initiating at the lowest levels of the cortical visual pathway or commences at higher-tier regions. We previously examined modal completion (Murray et al., 2002) and provided evidence that the earliest modal IC sensitivity occurs within higher-tier object recognition areas of the lateral occipital complex (LOC). We further proposed that previous observations of IC sensitivity in lower-tier regions likely reflect feedback modulation from the LOC. The present study tested these proposals, examining the commonality between modal and amodal completion mechanisms with high-density electrical mapping, spatiotemporal topographic analyses, and the local autoregressive average distributed linear inverse source estimation. A common initial mechanism for both types of completion processes (140 msec) that manifested as a modulation in response strength within higher-tier visual areas, including the LOC and parietal structures, is demonstrated, whereas differential mechanisms were evident only at a subsequent time period (240 msec), with amodal completion relying on continued strong responses in these structures.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In order to estimate the motion of an object, the visual system needs to combine multiple local measurements, each of which carries some degree of ambiguity. We present a model of motion perception whereby measurements from different image regions are combined according to a Bayesian estimator --- the estimated motion maximizes the posterior probability assuming a prior favoring slow and smooth velocities. In reviewing a large number of previously published phenomena we find that the Bayesian estimator predicts a wide range of psychophysical results. This suggests that the seemingly complex set of illusions arise from a single computational strategy that is optimal under reasonable assumptions.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Background: We and others have described the neurodegenerative disorder caused by G51D SNCA mutation which shares characteristics of Parkinson’s disease (PD) and multiple system atrophy (MSA). The objective of this investigation was to extend the description of the clinical and neuropathological hallmarks of G51D mutant SNCA-associated disease by the study of two additional cases from a further G51D SNCA kindred and to compare the features of this group with a SNCA duplication case and a H50Q SNCA mutation case. Results: All three G51D patients were clinically characterised by parkinsonism, dementia, visual hallucinations, autonomic dysfunction and pyramidal signs with variable age at disease onset and levodopa response. The H50Q SNCA mutation case had a clinical picture that mimicked late-onset idiopathic PD with a good and sustained levodopa response. The SNCA duplication case presented with a clinical phenotype of frontotemporal dementia with marked behavioural changes, pyramidal signs, postural hypotension and transiently levodopa responsive parkinsonism. Detailed post-mortem neuropathological analysis was performed in all cases. All three G51D cases had abundant α-synuclein pathology with characteristics of both PD and MSA. These included widespread cortical and subcortical neuronal α-synuclein inclusions together with small numbers of inclusions resembling glial cytoplasmic inclusions (GCIs) in oligodendrocytes. In contrast the H50Q and SNCA duplication cases, had α-synuclein pathology resembling idiopathic PD without GCIs. Phosphorylated α-synuclein was present in all inclusions types in G51D cases but was more restricted in SNCA duplication and H50Q mutation. Inclusions were also immunoreactive for the 5G4 antibody indicating their highly aggregated and likely fibrillar state. Conclusions: Our characterisation of the clinical and neuropathological features of the present small series of G51D SNCA mutation cases should aid the recognition of this clinico-pathological entity. The neuropathological features of these cases consistently share characteristics of PD and MSA and are distinct from PD patients carrying the H50Q or SNCA duplication.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The nature of data has changed as human technology has evolved. ‘Natural’ analogue data stimulate our senses, whilst machine produced data provides an intermediary for natural or artificial data to our senses. In the age of the cyborg (a machine with human attributes) and the bionic person (a human with machine attributes), it is possible for data totally alien from ‘natural reality’ to be fed directly to the brain so by-passing the senses. This is a new form of reality, which lends itself to manipulation of a kind never experienced before. The dreams of deceivers may yet be realised on a mass scale.