PubMed Health⌕ Search

Biomedical subjects

R Schellenberg

Publications and source records attributed to R Schellenberg.

31 records · Page 2Linked to original sources
PubMed1990

Nasopharyngeally and vertex recorded P300's in normal subjects.

The P300 waveform has been associated with cognitive activity during information processing, and the hippocampus has been discussed as a possible generator of this waveform. This being the case some would argue that it should be possible to record the P300 with a shorter latency and greater amplitude from an electrode placed as near the hippocampus as possible. Under local anaesthesia we inserted a specially constructed needle electrode through the left nostril in the recessus pharyngeus close to the hippocampus. The results did not support the hippocampal hypothesis. Nasopharyngeally recorded P300's were found to have significantly decreased amplitudes and extended latencies when compared to vertex recordings.

Adult↗
PubMed1990

[Left hemispheric site of EEG findings in patients with schizophrenic psychoses].

It was the aim of our study to examine the interhemispherical and extrahemispherical integration that is possibly disturbed in patients suffering from schizophrenic psychoses, using an easy method of EEG performance spectral analysis. For this purpose, the EEG at rest and the functional EEG were determined in 69 schizophrenic patients (ICD) and 22 healthy subjects and the EEG reactivity was calculated. Differences especially in alpha-2 reactivity were seen both intrahemispherically and interhemispherically. This supports the concept of left hemispheric dysfunction in patients suffering from schizophrenic psychoses.

Adult↗
PubMed1989

Multivariate EEG power spectral analysis in acute schizophrenics.

The electroencephalogram (EEG) during information processing is influenced by specific changes in brain electrical activity. Based on the theory of disturbed information processing in schizophrenics, we analysed auditory stimulus induced EEG changes by Fast Fourier Transformation. The most important of the significant stimulation-dependent EEG power changes were measured in the 0.5-3.5 Hz and 10-13.5 Hz frequency bands in the left frontoparietal lead. In a multivariate analysis the separation of the subjects examined into acute schizophrenics and normals was incorrect in only 21% of the cases (resubstitution rate); using pi-method an error of 31% was estimated.

Acoustic Stimulation↗
PubMed1989

Repeated acoustic stimulation of acute schizophrenic patients and the habituation of EEG power changes.

Habituation in psychiatric patients to repeated stimuli has typically been described in connection with the measurement of the skin conductance orienting response. Here EEG power spectra of acute schizophrenic patients and normals to 4 trials of an acoustic stimulation were examined for evidence of habituation. In response to stimulation the alpha EEG reactivity was less distinct in schizophrenics than in normals. This is in agreement with the theory of hypovariability or hyperstability of the EEG in schizophrenics. Signs of habituation in acute schizophrenics were clearer in fast beta frequencies of the parietal leads.

Acoustic Stimulation↗
PubMed1989

[Pathophysiologic aspects of schizophrenic psychoses--a review].

The aim of research in the field of "Biological Psychiatry" is the phenomenological description of several aspects of psychiatric diseases and the exploration of their pathological mechanisms. The most used methods are biochemical, morphological, genetical, social psychiatric, neuro- and psychophysiological ones. From the pathophysiological view the most discussed hypothesis is that of a disturbed central information processing. In this paper a short introduction should be given on psychosocial influence on the development of psychotic symptomatology and on the periphere vegetative and electroencephalographic parameters in psychiatric patients.

Arousal↗
PubMed1988

[Multivariate discriminant analysis of EEG power spectra in acute schizophrenic patients and healthy probands].

The electroencephalogram (EEG) during information processing is influenced by specific changes in brain electrical activity. Based on the theory of a disturbed information processing in schizophrenics we analysed auditory stimulus induced EEG changes by Fast Fourier Transformation. The most important of the significant stimulation dependent EEG power changes were measured in the 0.5-3.5 Hz and 10-13.5 Hz frequency bands in the left parietal lead. In a multivariate analysis the separation of the subjects examined into acute schizophrenics and normals was incorrect in only 21% of the cases (resubstitution rate): using the pi-method an error of 31% was estimated.

Acute Disease↗
PubMed1981

[Effect of discontinuous hemorrhage on plasma and cerebrospinal fluid vasopressin concentration in anesthesized rabbits].

Repeated withdrawal of 15 ml arterial blood at 10 min intervals produced marked hypovolaemia and hypotension with plasma vasopressin concentration increasing exponentially from 53 microE/ml to more than 700 microE/ml contrary to the hypovolaemia. After the first blood withdrawal there exists a linear correlation between the increase of the plasma vasopressin concentration and the decrease of the mean arterial blood pressure. With 61.5 microE/ml the cerebrospinal fluid withdrawn following the last bleeding likewise showed a very high vasopressin level. After extraction of the hormone from plasma and cerebrospinal fluid the vasopressin concentration was determined by means of the antidiuretic bioassay in the water-loaded rat.

Animals↗
PubMedDate not supplied

Cyclandelate versus propranolol in the prophylaxis of migraine--a double-blind placebo-controlled study.

The aim of the present study was to ascertain the comparative efficacy of cyclandelate, a migraine prophylactic with calcium overload blocking properties, versus propranolol, a non-selective beta-adrenergic blocker, and placebo. Based on different statistical analysis procedures (including time series analysis) a responder and nonresponder evaluation for cyclandelate and propranolol was performed. In addition, an attempt was made to identify the dose relationship of the various drugs on headache parameters. In a double-blind placebo-controlled study 84 patients were treated in a placebo run-in phase (4 weeks). The patients were then randomized by the statistical criterion of placebo responder and nonresponder to either the cyclandelate or the propranolol group. The total treatment period included a low-dosage phase (8 weeks) and high-dosage phase (8 weeks). All patients kept a headache diary before, during and after treatment. The data were assessed by time series analysis (ARIMA), as well as by analysis of variance and nonparametric statistics. Based on ARIMA statistics, 39.3% of the patients showed a significant improvement of migraine during treatment with cyclandelate compared with 29.4% placed on propranolol. Higher doses of cyclandelate and propranolol were more effective. Using the qualitative response-criterion of a 50% reduction in migraine symptoms, cyclandelate showed a response in 67.9% and propranolol in 41.2% of all cases. It can therefore be concluded that cyclandelate as well as propranolol are two comparable substances in the prophylactic treatment of migraine, with cyclandelate showing fewer side effects.

Adolescent↗