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Ralf Hemmingsen

Publications and source records attributed to Ralf Hemmingsen.

13 recordsLinked to original sources
PubMed2005

Assessment of in vivo MR imaging compared to physical sections in vitro--a quantitative study of brain volumes using stereology.

The object of the present study was to compare stereological estimates of brain volumes obtained in vivo by magnetic resonance imaging (MRI) to corresponding volumes from physical sections in vitro. Brains of ten domestic pigs were imaged using a 3-T scanner. The volumes of different brain compartments were obtained from MR images by two observers and from physical sections using the Cavalieri estimator in combination with point counting. Paired t tests revealed no significant differences between the two methods for any of the five compartments considered, except for the basal gray compartment. However, although intraobserver difference of MRI estimates was acceptable, the interobserver difference was not. A statistical highly significant difference of 11-41% was observed between observers for volume estimates of all compartments considered. The study demonstrates that quantitative MRI is susceptible to observer dependent interpretation of images.

Algorithms↗
PubMed2005

Acquisition of visually guided conditional associative tasks in Göttingen minipigs.

Fourteen Göttingen minipigs were trained on two different visually guided conditional associative tasks. In a spatial conditional task, a black stimulus signalled that a response to the left was correct, and a white stimulus signalled that a response to the right was correct. In a conditional go/no-go task, a blue stimulus signalled go, and a red stimulus signalled no-go. The pigs were trained until a behavioural criterion of 90% correct for each of two consecutive sessions. For the spatial conditional task, all pigs reached this criterion in 520 trials or less. For the conditional go/no-go task, all pigs, except three, reached this criterion in 1600 trials or less. Sows and boars learned equally fast. The tasks can be useful for the testing of cognitive function in pig models of human brain disorders.

Animals↗
PubMed2005

Integrated treatment of first-episode psychosis: effect of treatment on family burden: OPUS trial.

BACKGROUND: The families of patients with first-episode psychosis often play a major role in care and often experience lack of support. AIMS: To determine the effect of integrated treatment v. standard treatment on subjective burden of illness, expressed emotion (EE), knowledge of illness and satisfaction with treatment in key relatives of patients with a first episode of schizophrenia-spectrum disorder. METHOD: Patients with ICD-10 schizophrenia-spectrum disorders (first episode) were randomly assigned to integrated treatment or to standard treatment. Integrated treatment consisted of assertive community treatment, psychoeducational multi-family groups and social skills training. Key relatives were assessed with the Social Behaviour Assessment Schedule (SBAS, burden of illness), the 5-min speech sample (EE), and a multiple choice questionnaire at entry and after 1 year. RESULTS: Relatives in integrated treatment felt less burdened and were significantly more satisfied with treatment than relatives in standard treatment. There were no significant effects of intervention groups on knowledge of illness and EE. CONCLUSIONS: The integrated treatment reduced family burden of illness and improved satisfaction with treatment.

Adaptation, Psychological↗
PubMed2004

Discriminations, reversals, and extra-dimensional shifts in the Göttingen minipig.

Göttingen minipigs were trained on a set-shifting procedure involving discriminations, reversals, and extra-dimensional shifts. The discriminations used were black-white discriminations and right-left discriminations. The initial visual and spatial discrimination seemed equally difficult, and only for the visual modality was reversal found to be more difficult than the initial discrimination. Visual reversal was more difficult than spatial reversal, and a larger number of perseverative sessions were found for visual reversal compared to spatial reversal. The acquisition of the extra-dimensional shift from the visual to the spatial dimension was not inferior to the learning of spatial reversal. Neither was the acquisition of the extra-dimensional shift from the spatial to the visual dimension inferior to the learning of visual reversal. Thus, no evidence was found for attention to stimulus dimensions in discrimination learning of the pigs.

Animals↗
PubMed2004

Prepulse inhibition in patients with Alzheimer's disease.

Prepulse inhibition (PPI) is used as a measure for sensorimotor gating. Studies in animals have indicated that hippocampus and entorhinal cortex, structures which are affected in mild Alzheimer's disease (AD), are involved in the regulation of PPI. The objectives of this study were to determine if patients with very mild AD had altered PPI, and to study possible correlations between PPI and cognitive performance or neuropsychiatric symptoms. A passive acoustic PPI paradigm was applied in 48 patients with either mild AD or Mild Cognitive Impairment (MCI) and in 49 healthy controls. No differences were found between patients and healthy controls regarding PPI. Further, PPI was not found to correlate with cognitive performance or neuropsychiatric symptoms. PPI is significantly altered in patients with neuropsychiatric disorders associated with dopaminergic, glutamatergic and/or serotonergic dysfunctions, such as schizophrenia. Since mild AD is primarily associated with loss of cholinergic markers in the limbic regions this study suggests that acetylcholine only plays a minor role in the regulation of PPI.

Acetylcholine↗
PubMed2003

Psychiatric morbidity in a neurology-based memory clinic: the effect of systematic psychiatric evaluation.

OBJECTIVES: To estimate the prevalence of psychiatric morbidity and the effect of systematic psychiatric evaluation in patients referred to a memory clinic in a neurological setting. DESIGN: Descriptive case-series study in consecutive referrals to a memory clinic. SETTING: An outpatient multidisciplinary memory clinic in a neurological setting. PARTICIPANTS: An index group of 100 consecutive patients (aged 60-89) referred for diagnostic evaluation of cognitive symptoms during a period of 8 months and a reference group of 686 consecutive patients (aged 60-98) referred during a previous period of 54 months. In the index group, a systematic psychiatric evaluation was performed in addition to the neurological evaluation and routine investigations. In the reference group, patients had the same basic evaluation, but psychiatric evaluation was optional and was performed in 21% of the patients. MEASUREMENTS: Prevalence of primary psychiatric morbidity in the index and reference groups according to international clinical criteria and multidisciplinary consensus report and three key psychiatric symptoms: delusions, hallucinations, and affective symptoms in the index group. RESULTS: Twenty-three percent of patients in the index group had a primary psychiatric disease. A primary psychiatric disease was diagnosed in 8% of patients in the reference group (P<.001). One or more psychiatric symptoms were identified in 72% of all patients in the index group. CONCLUSION: Psychiatric conditions and symptoms are frequent in elderly patients with cognitive symptoms, including those referred to a neurological memory clinic. The data provide evidence for a multispecialty and multidisciplinary approach to the diagnosis and management of patients with possible dementia.

Aged↗
PubMed2002

Psychiatric emergency outreach: a report on the first 2 years of functioning in Copenhagen.

The purpose of the study was to evaluate psychiatric emergency outreach after functioning for a period of 2 years in Copenhagen, Denmark. Psychiatric emergency outreach was staffed by a psychiatrist and an ambulance driver, and the target group was defined as mentally ill and persons in severe crisis. For each of 935 calls covering 777 different patients, a registration form with social and clinically relevant data was filled out. After the 2-year period, patients were looked up in the National Cause of Death Register and the National Psychiatric Case Register. A total of 66% were previously registered as psychiatric patients, and in 37% of all calls, the patient had psychotic symptoms. In 25% of the calls, the patient was admitted to psychiatric hospital; 38% of the admissions were involuntary. Forty-eight per cent of the calls were initiated by relatives, friends or neighbours. Suicidal behaviour was frequent. There were significantly more calls in socially deprived areas. Standard Mortality Rates were high for all causes of death (5.00), and especially for suicide (31.98). In conclusion, psychiatric emergency outreach seems to fulfil some of its purpose.

Adolescent↗
PubMed2002

Spontaneous object recognition in the Göttingen minipig.

Göttingen minipigs were tested in an object recognition procedure based on spontaneous exploration. Eight pigs were exposed to two similar objects in a sample trial and after a one-hour delay exposed to two objects, one familiar and one novel, in a test trial. The pigs explored the novel object significantly more than the familiar object in the test trial (p<0.05), thereby showing recognition of the familiar object. Furthermore, habituation of exploration of the familiar object between the sample trial and the test trial was found (p<0.05). The procedure can be useful for testing of spontaneous trial-unique memory in pigs.

Animals↗
PubMed1999

Dopaminergic sensitization of rats with and without early prefrontal lesions: implications for the pathogenesis of schizophrenia.

To study whether an early lesion of prefrontal cortex (PFC) would influence mesolimbic dopaminergic sensitization induced by intermittent electrical stimulation (IES) of the ventral tegmental area (VTA) or change social interactions in animals exposed to both electrical sensitization and prefrontal lesions, we examined the behaviour of rats with or without early prefrontal lesions following repeated electrical stimulation of the VTA. Additionally, we wanted to study the influence of immobilization stress on rats exposed to a combination of prefrontal lesion and daily restraint in Plexiglas tubes prior to IES. Neither early lesion of PFC nor repeated restraint influenced development of sensitization. However, the combination of early prefrontal lesion and IES resulted in changes in social interactions neither seen following IES nor in lesioned rats. The changes were most pronounced in the group exposed to both IES, prefrontal lesions and restraint. Furthermore, repeated restraint caused a significant increase in the threshold current for provocation of the behavioural response related to VTA stimulation (head stereotypies/sniffing). The implications of the findings for sensitization of the mesolimbic dopaminergic system as a model for development of schizophrenia are discussed.

Journal Article↗