Helping You Find Full Text Journal Articles

Search Results:

Author: Karsten Heekeren (34)


Feb
2018

Simultaneous PET/MR/EEG (Positron Emission Tomography - Magnetic Resonance - Electroencephalography), a new tool for the investigation of neuronal networks in the human brain, is presented here within the framework of the European Union Project TRIMAGE. The trimodal, cost-effective PET/MR/EEG imaging tool makes use of cutting edge technology both in PET and in MR fields. A novel type of magnet (1.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Schizophrenia is characterized by positive and negative symptoms and cognitive dysfunction. The glutamate hypothesis of schizophrenia has been hypothesized to explain the negative symptoms and cognitive deficits better than the dopamine hypothesis alone. Therefore, we aimed to evaluate whether glutamatergic variants such as d-amino acid oxidase (), DAO activator ()/, and neuregulin 1 () single-nucleotide polymorphisms (SNPs) and their mRNA levels predicted (i) transition to schizophrenia spectrum disorders and (ii) research domain criteria (RDoC) domains, mainly negative valence and cognitive systems.

View Full Text PDF Listings View primary source full text article PDFs.

Apr
2017

Presentation of attenuated positive psychotic symptoms (APS) was reported to be modestly influenced by age, sex and education in a psychosis-risk sample. We re-examined the influence of demographic variables on APS in an independent psychosis-risk sample.
In a clinical high-risk-sample (N = 188; 13-35 years; 60.

View Full Text PDF Listings View primary source full text article PDFs.

Nov
2017

The aim of this study was to test the validity of the CHR state by focusing on the course of psychosis spectrum symptoms, depression and global functioning in converters and non-converters. A total of 188 CHR-positive subjects (60.2% men) aged between 13 and 35years (mean=20.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Reduction in hippocampal volume is a hallmark of schizophrenia and already present in the clinical high-risk state. Nevertheless, other subcortical structures, such as the thalamus, amygdala and pallidum can differentiate schizophrenia patients from controls. We studied the role of hippocampal and subcortical structures in clinical high-risk individuals from two cohorts.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
2016

An important aim in schizophrenia research is to optimize the prediction of psychosis and to improve strategies for early intervention. The objectives of this study were to explore neurocognitive performance in individuals at risk for psychosis and to optimize predictions through a combination of neurocognitive and psychopathological variables. Information on clinical outcomes after 24 months was available from 118 subjects who had completed an extensive assessment at baseline.

View Full Text PDF Listings View primary source full text article PDFs.

Sep
2016

Interest in subtypes of mental disorders is growing in parallel with continuing research progress in psychiatry. The aim of this study was to examine pure animal phobia in contrast to other specific phobias and a mixed subtype. Data from three representative Swiss community samples were analysed: PsyCoLaus (n = 3720), the ZInEP Epidemiology Survey (n = 1500) and the Zurich Study (n = 591).

View Full Text PDF Listings View primary source full text article PDFs.

Feb
2016

The Loudness Dependence of Auditory Evoked Potentials (LDAEP) is considered as an indicator of central serotonergic activity. Alteration of serotonergic neurotransmission was reported in bipolar disorders and schizophrenia. In line with previous reports on clinically manifest disorders, we expected a weaker LDAEP in subjects at risk for bipolar disorders and schizophrenia compared to healthy controls.

View Full Text PDF Listings View primary source full text article PDFs.

Aug
2015

According to stress-vulnerability models, social stressors contribute to the onset of schizophrenia. Stigma and discrimination associated with mental illness may be a stressor for young people at risk of psychosis even prior to illness onset, but quantitative longitudinal data on this issue are lacking. We examined the cognitive appraisal of stigma-related stress as predictor of transition to schizophrenia among young people at risk of psychosis.

View Full Text PDF Listings View primary source full text article PDFs.

Feb
2016

Mental health service use is helpful but rare among young people at risk of psychosis. The label and stigma associated with mental illness may affect attitudes towards help-seeking. We examined 67 individuals at risk of psychosis over the course of 1 year.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

There is growing evidence that reward processing is disturbed in schizophrenia. However, it is uncertain whether this dysfunction predates or is secondary to the onset of psychosis. Studying 21 unmedicated persons at risk for psychosis plus 24 healthy controls (HCs) we used a incentive delay paradigm with monetary rewards during functional magnetic resonance imaging.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Early detection of persons with first signs of emerging psychosis is regarded as a promising strategy to reduce the burden of the disease. In recent years, there has been increasing interest in early detection of psychosis and bipolar disorders, with a clear need for sufficient sample sizes in prospective research. The underlying brain network disturbances in individuals at risk or with a prodrome are complex and yet not well known.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Human cortical somatosensory evoked potentials (SEPs) allow an accurate investigation of thalamocortical and early cortical processing. SEPs reveal a burst of superimposed early (N20) high-frequency oscillations around 600 Hz. Previous studies reported alterations of SEPs in patients with schizophrenia.

View Full Text PDF Listings View primary source full text article PDFs.

Sep
2014

Stigma may undermine the well-being of young people at risk of psychosis. We therefore measured self-labeling, stigma variables and well-being at baseline and again one year later among 77 at-risk participants. An increase in self-labeling during this period predicted heightened stigma stress after one year and a decrease in stigma stress predicted better well-being at follow-up, controlling for symptoms, psychiatric comorbidity and sociodemographic variables.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2014

The N400, an event-related brain potential (ERP), can be triggered by semantic or arithmetic violations in visual or auditory stimulus material. Schizophrenia patients exhibit an altered N400 presumably resulting from impaired semantic memory associative networks. The present study investigates, whether an altered N400 can also be found in semantic violations of the own self-concept.

View Full Text PDF Listings View primary source full text article PDFs.

Apr
2014

When young people at risk of psychosis experience early signs of the disorder or early intervention, they may label themselves as "mentally ill." However, empirical data related to the potentially harmful effects of self-labeling and stigma among young people at risk of psychosis are lacking. This study used a stress-coping model to examine mechanisms by which stigma may exert an impact on young people at risk of psychosis.

View Full Text PDF Listings View primary source full text article PDFs.

Sep
2014

The task-positive network (TPN) is anticorrelated with activity in the default mode network (DMN), and possibly reflects competition between the processing of external and internal information, while the salience network (SN) is pivotal in regulating TPN and DMN activity. Because abnormal functional connectivity in these networks has been related to schizophrenia, we tested whether alterations are also evident in subjects at risk for psychosis. Resting-state functional magnetic resonance imaging was tested in 28 subjects with basic symptoms reporting subjective cognitive-perceptive symptoms; 19 with attenuated or brief, limited psychotic symptoms; and 29 matched healthy controls.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
2013

The role of self-labeling as 'mentally ill' and of stigma-related stress for help-seeking among young people at risk for psychosis is unknown. Stronger self-labeling and less stigma stress predicted better attitudes towards psychiatric medication and psychotherapy, controlling for clinical and sociodemographic variables. Interventions could target stigma-related stress to increase help-seeking.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Negative symptoms have been considered to be specific to schizophrenia or a subtype of schizophrenia: the deficit syndrome. In other words, these symptoms have been considered to be categorically different from other forms of human behavior and experience, whether they occur in healthy persons or patients with other psychiatric disorders. In this paper, we advocate a dimensional approach to negative symptoms, which is supported by two main arguments.

View Full Text PDF Listings View primary source full text article PDFs.

Oct
2008

Passivity experiences are hallmark symptoms of schizophrenia that can be characterized by the belief that one's thoughts or actions are controlled by an external agent. It has recently been suggested that these psychotic experiences result from defective monitoring of one's own actions, i.e.

View Full Text PDF Listings View primary source full text article PDFs.

Nov
2008

Attentional deficits are common symptoms in schizophrenia. Recent evidence suggests that schizophrenic patients show abnormalities in spatial orienting of attention, particularly a deficit of inhibition of return (IOR). IOR is mostly thought to reflect an automatic, inhibitory mechanism protecting the organism from redirecting attention to previously scanned, insignificant locations.

View Full Text PDF Listings View primary source full text article PDFs.

Jul
2008

Many studies have reported deficits of mismatch negativity (MMN) in schizophrenic patients. Pharmacological challenges with hallucinogens in healthy humans are used as models for psychotic states. Previous studies reported a significant reduction of MMN after ketamine (N-methyl-D-aspartate acid [NMDA] antagonist model) but not after psilocybin (5HT2A agonist model).

View Full Text PDF Listings View primary source full text article PDFs.

Dec
2007

In typical orienting of attention tasks subjects have to respond as fast as possible to targets which appear in the periphery of the visual field and are preceded by spatial cues (e.g. brightening of a peripheral box where the target may subsequently appear).

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2007

Contemporary theories of motor control assume that motor actions underlie a supervisory control system which utilizes reafferent sensory feedbacks of actions for comparison with the original motor programs. The functional network of visuomotor action monitoring is considered to include inferior parietal, lateral and medial prefrontal cortices. To study both sustained monitoring for visuomotor incongruence and the actual detection of incongruence, we used a hybrid fMRI epoch-/event-related design.

View Full Text PDF Listings View primary source full text article PDFs.

Feb
2006

Patients with schizophrenia exhibit disturbances of orienting of attention. However, findings have been inconsistent. Pharmacologic challenges with hallucinogens have been used as models for psychosis.

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2006

Previous studies on spatial orienting of attention in schizophrenia demonstrated a deficit of Inhibition of Return (IOR). However, other studies reported a delay in the manifestation, but an overall normal amount of IOR in patients with schizophrenia. However, the latter studies used a cue-back manipulation which is known to reinstate or speed up IOR.

View Full Text PDF Listings View primary source full text article PDFs.

Aug
2005

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is neurotoxic in animal studies and its use has been associated with cognitive impairments in humans.
To study hippocampal activation during the retrieval from episodic memory in polyvalent users of ecstasy.
Twelve polyvalent ecstasy users and twelve matched controls were examined by means of functional magnetic resonance imaging (fMRI) while they retrieved face-profession associations from episodic memory.

View Full Text PDF Listings View primary source full text article PDFs.

Sep
2004

Working memory processing in ecstasy (3,4-methylenedioxymethamphetamine) users is associated with neural alterations as measured by functional magnetic resonance imaging. Here, we examined whether cortical activation patterns change after prolonged periods of continued use or abstinence from ecstasy and amphetamine.
We used an n-back task and functional magnetic resonance imaging in 17 ecstasy users at baseline (t(1)) and after 18 months (t(2)).

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

There is increasing evidence for an influence of directed attention on prepulse inhibition (PPI) of the acoustic startle reflex. However, the existing paradigms for the assessment of this effect have methodological problems and pitfalls. In particular, most previous studies used a paradigm which directed the attention of subjects to the prepulse only.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2004

Previous cross-sectional studies on covert orienting of visual attention in schizophrenia have been inconsistent. In the present longitudinal study, we examined 40 medicated acutely ill inpatients with a covert orienting of attention task (COVAT) shortly after admission, and again 12-16 weeks after the initial examination, while most patients were in (partial) remission. We administered a COVAT with nonpredictive peripheral cues and two stimulus-onset asynchronies (SOA; 100 and 800 ms).

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2004

The diagnosis kleptomania is based on diagnostic criteria which describe a particular distinctive behaviour. Both the DSM-IV and the WHO-ICD10 neglect the different etiologic possibilities. The high co-morbidity of kleptomania with other mental disorders is another problem.

View Full Text PDF Listings View primary source full text article PDFs.

May
2004

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is neurotoxic upon central serotonin systems in experimental animals and probably also in humans. Serotonin is involved in the habituation, sensitization and prepulse inhibition (PPI) of the startle reflex.
To study the plasticity of startle reflex in currently abstinent MDMA users.

View Full Text PDF Listings View primary source full text article PDFs.

Back to top