Biomedical subjects

Bernhard Blanz

Publications and source records attributed to Bernhard Blanz.

6 recordsLinked to original sources

PubMed2006

Impaired working speed and executive functions as frontal lobe dysfunctions in young first-degree relatives of schizophrenic patients.

The aim of the investigation was to detect neuropsychological markers, such as sustained and selective attention and executive functions, which contribute to the vulnerability to schizophrenia especially in young persons. Performance was assessed in 32 siblings and children of schizophrenic patients and 32 matched controls using Wisconsin Card Sorting Test, Colour-Word-Interference-Test, Trail Making Test, and d2-Concentration-Test. The first-degree relatives showed certain impairments on all four tests, in particular, slower times on all time-limited tests. These results suggest the need for more time when completing neuropsychological tasks involving selected and focused attention, as well as cognitive flexibility, as a possible indicator of genetic vulnerability to schizophrenia.

Adolescent↗

PubMed2006

Changes of pain perception, autonomic function, and endocrine parameters during treatment of anorectic adolescents.

OBJECTIVES: The underlying mechanisms of reduced pain perception in anorexia nervosa (AN) are unknown. To gain more insight into the pathology, the authors investigated pain perception, autonomic function, and endocrine parameters before and during successful treatment of adolescent AN patients. METHOD: Heat pain perception was assessed in 15 female adolescent AN patients and matched controls. Results were correlated with autonomic and endocrine parameters (free triiodothyronine, free cortisol). Autonomic function was studied using heart rate variability and pupillary light reflex assessment. To investigate the influence of therapy on these parameters, data were obtained at three different time points. RESULTS: Heat pain thresholds were significantly increased in the acute state and decreased after weight had been regained for 6 months. Similarly, an increased parasympathetic tone was present in the acute state only. The relative amplitude of the pupillary light reflex showed a positive correlation to pain thresholds over time and predicted disease progression. In addition, the authors found a negative correlation between increased pain thresholds and low free cortisol. CONCLUSION: Increased pain thresholds are associated with increased parasympathetic tone and a hypothyroid state in AN. This may either indicate common central mechanisms or suggest a causative interaction.

Adolescent↗

PubMed2004

[First effects of training phonological awareness in two age cohorts of kindergarten children].

OBJECTIVE: This study investigated to what extent young kindergarten children already benefit from training phonological awareness. METHODS: The training program used here was the German "Würzburg training program of phonological awareness". The control group participated in the regular kindergarten program. A total of 80 children, one and two years before entering school, participated in the study. Tests of phonological awareness were assessed before and after the training as well as after six months. RESULTS: Young kindergarten children (two years before entering school) compared to preschoolers (one year before entering school) had significant lower phonological awareness skills. However both cohorts showed noticeable significant training effects, but preschoolers benefited significantly more from training phonological awareness. Long-term effects were obtained for both cohorts. CONCLUSIONS: Already young kindergarten children do benefit effectively from preschool phonological awareness training. Effects of this training on reading and spelling in school will be investigated further.

Age Factors↗

PubMed2002

Phonological processing in dyslexic children: a study combining functional imaging and event related potentials.

Difficulties in phonological processing are currently considered one of the major causes for dyslexia. Nine dyslexic children and eight control children were investigated using functional magnetic resonance imaging (fMRI) during non-oral reading of German words. All subjects silently read words and pronounceable non-words in an event related potentials (ERP) investigation, as well. The fMRI showed a significant difference in the activation in the left inferior frontal gyrus between the dyslexic and control groups, resulting from a hyperactivation in the dyslexics. The ERP scalp distribution showed a significant distinction between the two groups concerning the topographic difference for left frontal electrodes in a time window 250-600 ms after stimulus onset for non-word reading. Both the fMRI and the ERP results support differences in phonological processing between dyslexic and normal-reading children.

Child↗

PubMed2002

How to avoid spurious cluster validation? A methodological investigation on simulated and fMRI data.

This paper presents an evaluation of a common approach that has been considered as a promising option for exploratory fMRI data analyses. The approach includes two stages: creating from the data a sequence of partitions with increasing number of subsets (clustering) and selecting the one partition in this sequence that exhibits the clearest indications of an existing structure (cluster validation). In order to achieve that the selected partition is actually the best characterization of the data structure, previous studies were directed to find the most appropriate validity function(s). In our analysis protocol, we first optimize the sequence of partitions according to the given objective function. Our study showed that an insufficient optimization of the partition, for one or more numbers of clusters, can easily yield a spurious validation result which, in turn, may lead the analyst to a misleading interpretation of the fMRI experiment. However, a sufficient optimization, for each included number of clusters, provided the basis for a reliable, adequate characterization of the data Furthermore, it enabled an adequate evaluation of the validity functions. These findings were obtained independently for three clustering algorithms (representing the hard and fuzzy clustering variant) and three up-to-date cluster validity functions. The findings were derived from analyses of Gaussian clusters, simulated data sets that mimic typical fMRI response signals, andreal fMRI data. Based on our results we propose a number of options of how to configure improved clustering tools.

Algorithms↗

PubMed2002

Multicenter P300 brain mapping of impaired attention to cues in hyperkinetic children.

OBJECTIVE: To measure specific neurophysiological attention deficits in children with hyperkinetic disorders (HD; the ICD-10 diagnosis for severe and pervasive attention-deficit/hyperactivity disorder [ADHD]). METHOD: In a multicenter sample of 148 children with HD and control children aged 8 to 14 years, event-related potential maps were recorded during a cued continuous performance test (A-X/O-X). Maps to cues (requiring attention but no response) and distractors and performance were tested for differences between age- and sex-matched HD and control groups (n = 57 each), as well as between clinics (n = 5). RESULTS: The N1, P3a, and P3b maps revealed reliable attention effects, with larger amplitudes after cues than after distractors, and only minor differences across clinics. Children with HD missed more targets, made more false alarms, and had larger N1 followed by smaller P3b amplitudes after cues than did controls. Cue-P3b amplitude correlated with detecting subsequent targets. Cue-P3b tomography indicated posterior sources that were attenuated in children with HD. CONCLUSIONS: Brain mapping indicates that children with HD attend to cues (preceding potential targets) with increased initial orienting (N1) followed by insufficient resource allocation (P3b). These multiple, condition-specific attention deficits in HD within 300 msec extend previous results on ADHD and underline the importance of high temporal resolution in mapping severe attention deficits.

Adolescent↗