Biomedical subjects

Bernd Gallhofer

Publications and source records attributed to Bernd Gallhofer.

10 recordsLinked to original sources

PubMed2006

Brain activation during mental maze solving.

BACKGROUND: So-called Porteus mazes are used to investigate prefrontal cortex (PFC) functioning in normal subjects and patients with different neuropsychiatric disorders. Here we present data confirming the involvement of the PFC for the first time by means of functional magnetic resonance imaging (fMRI). To minimize motor-related activation, mental mazes were used. METHODS: Mazes as well as pseudo-mazes without any bifurcations were presented to 49 healthy participants during fMRI scans. RESULTS: Both, mazes as well as pseudo-mazes, activated a large network from visual to parietal regions, reflecting the dorsal stream of visual information processing. Mazes but not pseudo-mazes also activated bilateral areas of the PFC indicating their special role in decision processes. In addition, although no motor response was required during maze performance, both tasks activated subcortical and cortical motor areas. CONCLUSIONS: These tasks are suitable for investigating and specifying PFC functioning and its impairment in psychiatric disorders such as schizophrenia. In addition, mental mazes might be a suitable task for the investigation of patients with motor disturbances.

Adolescent↗

PubMed2006

Imaging gene-substance interactions: the effect of the DRD2 TaqIA polymorphism and the dopamine agonist bromocriptine on the brain activation during the anticipation of reward.

Dopamine is known as the main neurotransmitter modulating the activation of the reward system of the brain. The DRD2 TaqIA polymorphism is associated with dopamine D2 receptor density which plays an important role in the context of reward. Persons carrying an A1 allele have a lower D2 receptor density and a higher risk to show substance abuse. The present study was designed to investigate the influence of the DRD2 TaqIA polymorphism and the selective D2 receptor agonist bromociptine on the activation of the reward system by means of functional magnetic resonance imaging (fMRI). In a double-blind crossover study with 24 participants we found an increase of reward system activation from placebo to bromocriptine only in subjects carrying the A1 allele. Furthermore, only A1 carrier showed an increase of performance under bromocriptine. The results are interpreted as reflecting a specific sensitivity for dopamine agonists in persons carrying an A1 allele and may complement actual data and theories of the development of addiction disorders postulating a higher genetic risk for substance abuse in carrier of the A1 allele.

Adolescent↗

PubMed2005

Oxytocin modulates neural circuitry for social cognition and fear in humans.

In non-human mammals, the neuropeptide oxytocin is a key mediator of complex emotional and social behaviors, including attachment, social recognition, and aggression. Oxytocin reduces anxiety and impacts on fear conditioning and extinction. Recently, oxytocin administration in humans was shown to increase trust, suggesting involvement of the amygdala, a central component of the neurocircuitry of fear and social cognition that has been linked to trust and highly expresses oxytocin receptors in many mammals. However, no human data on the effects of this peptide on brain function were available. Here, we show that human amygdala function is strongly modulated by oxytocin. We used functional magnetic resonance imaging to image amygdala activation by fear-inducing visual stimuli in 15 healthy males after double-blind crossover intranasal application of placebo or oxytocin. Compared with placebo, oxytocin potently reduced activation of the amygdala and reduced coupling of the amygdala to brainstem regions implicated in autonomic and behavioral manifestations of fear. Our results indicate a neural mechanism for the effects of oxytocin in social cognition in the human brain and provide a methodology and rationale for exploring therapeutic strategies in disorders in which abnormal amygdala function has been implicated, such as social phobia or autism.

Adolescent↗

PubMed2005

Feedback about previous action improves executive functioning in schizophrenia: An analysis of maze solving behaviour.

Disturbances of executive functions (EF) in schizophrenia have received special attention during the past years, but there is still an ongoing debate whether impairment in EF tasks can be linked to deficits of EF themselves or if they rather reflect impairment of other cognitive functions such as working memory processes that are additionally required for task solving. In the present study, we analyzed whether impairments in the maintenance of previous processing assumed to be related to working memory contribute to the impairments in EF tasks seen in schizophrenia. Twenty-five schizophrenic patients treated with atypical antipsychotic agents and 25 healthy controls matched according to age, sex, and education were instructed to solve novel two-dimensional maze tasks by steering a pen through a system of paths. Low demands on maintaining previous actions by giving feedback on preceding movements (visualising the trace of the pen) were contrasted with high demands, i.e. without such a trace of past processing. Without feedback of previous action, task solution was less successful and the control of motor action was deficient in schizophrenic patients. With feedback, both domains of behaviour improved to the level of healthy controls at the costs of higher time demands. The behaviour of healthy controls was not influenced by the experimental manipulation. Lower demands on the maintenance of previous action seem to enable schizophrenic patients to perform executive functions successfully. But data suggest that task solving of schizophrenic patients is characterized by alterations in the coordination of executive functions with other cognitive processes.

Adult↗

PubMed2005

Acetylcholine esterase inhibitor donepezil improves dynamic cerebrovascular regulation in Alzheimer patients.

BACKGROUND: Alzheimer's disease (AD) leads to a degeneration of the nucleus basalis of Meynert and thus to decreased cholinergic tonus in the brain. The transcription of endothelial nitric oxide synthase depends on an adequate cholinergic innervation of microvessels and vasoregulative abnormalities have been reported in AD. We investigated activation-flow coupling to study the role of acetylcholine esterase inhibition (AChEI) on vasoregulative function. METHODS: A functional transcranial Doppler approach was used to measure the visually evoked flow velocity response in the posterior cerebral artery in AD patients who had no vascular risk factors. The diagnosis of AD was made according to the ICD10/DSMIIIR-criteria. After baseline recording the effect of four weeks 5mg donepezil and then four weeks 10 mg was investigated. Doppler data were evaluated with a control system approach to obtain dynamic properties of vasoregulation and were compared with a healthy control group. RESULTS: AD patients showed an increased damping (0.64 +/- 0.2; p = 0.007 vs. control) in evoked responses and lower resting flow velocity levels (40 +/- 13 cm/s; p = 0.06 vs. control), which were restored in a dose-dependent manner under AChEI (0.4 +/- 0.2; 44 +/- 11 cm/s). CONCLUSIONS: AD is associated with a functional vasoregulative deficit possibly due to decreased levels of the endothelial nitric oxide synthase. Augmenting levels with AChEI normalized flow regulation possibly leading to a better blood supply to active neurons.

Aged↗

PubMed2005

The FOCIS international survey on psychiatrists' opinions on cognition in schizophrenia.

BACKGROUND: The goal of this project was to develop an interview to evaluate psychiatrists' views on the nature of cognitive dysfunction in schizophrenia, its importance as a potential treatment target, and its relative importance as a treatment target across different phases of schizophrenia. MATERIALS AND METHODS: A survey (available in paper or on-line) consisting of 27 questions, was developed by the Focus on Cognition in Schizophrenia (FOCIS) group, and distributed in a single wave mailing to 63,295 psychiatrists in 21 countries worldwide. RESULTS: The overall response rate was 4.7% (n=2975). The surveyed psychiatrists perceived cognition as a high treatment priority in stabilized schizophrenia patients, but less so for first episode or acute schizophrenia patients. The potential of atypical antipsychotics to improve cognitive dysfunction in schizophrenia was identified by 81% of the respondent psychiatrists. CONCLUSIONS: Cognitive deficits in people with schizophrenia are seen by clinical psychiatrists as relevant to treatment and rehabilitation plans. They were, however, regarded as a higher treatment priority in stabilized chronic rather than in first episode patients. The results suggest clinical psychiatrists need additional education regarding the nature of cognitive dysfunction in schizophrenia and its importance for psychosocial rehabilitation and community re-entry.

Attitude of Health Personnel↗

PubMed2005

Executive function and cognitive subprocesses in first-episode, drug-naive schizophrenia: an analysis of N-back performance.

OBJECTIVE: This study investigated changes in the cognitive architecture of N-back performance in schizophrenia. METHOD: N-back performance of 12 patients with first-episode, drug-naive schizophrenia and matched healthy comparison subjects was studied in a reaction-time decomposition paradigm. RESULTS: Imposition of a working memory load led to a significant drop in response accuracy in patients. Reaction-time decomposition suggested slowing of visuomotor and choice reaction processing as well as an inability of parallel processing directed by working memory. DISCUSSION: Although N-back tasks validly access working memory function as a neurocognitive trait in the illness, several additional subprocesses and the ability for cognitive parallel processing are altered and require further study in schizophrenia.

Adult↗

PubMed2002

[Schizophrenic patients, who still live in psychiatric hospitals despite decades of deinstitutionalization. Part 1 of the Hessian Deinstitutionalisation Study].

Deinstitutionalization (DI) of most of the chronic long-stay patients has taken place in the last decades in Germany. However, a "residual" group of patients often remains in psychiatric hospitals, with an ongoing controversy on an appropriate type of their care (community based vs. hospital). Clinical, functional and social characteristics of such schizophrenic patients still residing in the long-stay wards in the German state of Hesse after decades of DI are presented. The n = 266 patients investigated displayed a marked degree of negative symptoms and moderate positive symptoms but, however, severe social disabilities. In addition, the patients were very dependent in daily living, had an extremely impoverished social network and leisure activities. The findings contribute to the research on "difficult-to-place" patients described in the literature.

Activities of Daily Living↗

PubMed2002

[Subgroups and Prognosis of "Difficult-to-Place" Schizophrenic Long-Stay Patients: Distinguishing "Hard Core" Patients].

Long-standing processes of deinstitutionalization often display processes of selection that result in groups of patients with marked disability profiles left in hospital. According to the literature socially deviant and unacceptable behaviour are a main obstacle to living in the community. Therefore, a group of "remnant" chronic schizophrenic patients was analysed by means of a latent class analysis with indicators of social behaviour and compliance. Three different subgroups were found, one of which had an extremely poor level of adaptation. However, prognosis of staff with regard to patients' ability to live outside the psychiatric hospital, and the rates of patients being moved into the community in the course of subsequent deinstitutionalization were not different among the three groups. Characteristics of "most-difficult-to-place patients' " as discussed in the literature are called into question on the basis of the results of this study.

Adult↗

PubMed2002

[Subjective quality of life in severely disabled long-stay schizophrenic patients].

In the controversy about severely chronic mental patients, who still reside in the psychiatric hospital after decades of deinstitutionalization, their quality of life (QoL) has become a main topic. On the basis of a critique of the dominant, mere standardized approach to QoL this method is compared with a qualitative approach in such a schizophrenic "residual" patient group (n = 144). While in the standardized approach a high level of subjective QoL could be found that correlated positively with the duration of hospitalisation, the open interviews yielded specific experiences of deficiencies. The appraisal of the quality of life especially of chronic or hospitalized patients is reconsidered.

Adult↗