Biomedical subjects

Thomas Villmann

Publications and source records attributed to Thomas Villmann.

6 recordsLinked to original sources

PubMed2002

Correlation between automated writing movements and striatal dopaminergic innervation in patients with Wilson's disease.

Handwriting defects are an early sign of motor impairment in patients with Wilson's disease. The basal ganglia being the primary site of copper accumulation in the brain suggests a correlation with lesions in the nigrostiatal dopaminergic system. We have analysed and correlated striatal dopaminergic innervation using [(123)I]beta-CIT-SPECT and automated handwriting movements in 37 patients with Wilson's disease. There was a significant correlation of putaminal dopaminergic innervation with fine motor ability (p < 0,05 for NIV [number of inversion in velocity], NIA [number of inversion in acceleration], frequency). These data suggest that loss of dorsolateral striatal dopaminergic innervation has a pathophysiological function for decreased automated motor control in Wilson's disease. Furthermore analysis of automated handwriting movements could be useful for therapy monitoring and evaluation of striatal dopaminergic innervation.

Adult↗

PubMed2002

[Alternative German clusters for the core conflictual relationship theme method (CCRT)].

The Core Conflictual Relationship Theme Method (CCRT) is without doubt one of the most widely used relationship structure instruments in the field of psychodynamic psychotherapy research. Despite the important and sustained criticism of the German translation of the original Anglo-Saxon description of clusters and of standard categories, research in German-speaking countries still relies on this translation. This study aimed at developing an alternative German cluster version while maintaining the existing set of standard categories. This alternative cluster structure for the three CCRT components showed higher inner consistency while at the same time making more clinical sense. It also is promising in that it can be used with CCRTs scored using the original translation of the instrument. This first investigation of relationship patterns using the original and alternative clusters confirmed the increase of discriminant and convergent validity of the CCRT-method.

Adolescent↗

PubMed2002

Genotype correlation with fine motor symptoms in patients with Wilson's disease.

Wilson's disease, an autosomal recessive disorder of copper metabolism, is caused by about 200 different mutations of the ATP7B gene. Using a genotype-phenotype correlation, 36 patients were examined to see whether the disorder of the automatic handwriting movement depends on the genotype. The findings of this study indicated that no such link exists. Neither the profile of the impairment of the fine motor parameters nor the severity and frequency of pathological findings were different among the three genotype groups (homozygous for H1069Q, compound homozygous for H1069Q and other mutations). By contrast, fine motor disorders were found to correlate with the clinical symptoms recorded when therapy began. The pathophysiology of the basal ganglia and the cerebellar loop therefore cannot be directly attributed to the genotype of the mutation in the ATP7B gene.

Adenosine Triphosphatases↗

PubMed2001

[Central Relationship Patterns in Comparison with Different Objects]

In the present study the Relationship Episode Paradigm Interviews of 70 female patients with different psychoneurotic diseases were analysed with respect to object-specific patterns with the CCRT method. The most frequent categories are the same in all relationship episodes and in subsamples of relationship episodes with mother and father. These categories are also predominant in episodes with women and men. Relationship episodes with mother do not differ from episodes with father, and relationship episodes with women do not differ from episodes with men. But there are substantial differences in relationship episodes with the mother and women and between episodes with the father and men. Patients recount much more positive relationship patterns with women and men than with their parents. This could be understood as a hint of interpersonal resources.

Journal Article↗

PubMedDate not supplied

Generalized relevance learning vector quantization.

We propose a new scheme for enlarging generalized learning vector quantization (GLVQ) with weighting factors for the input dimensions. The factors allow an appropriate scaling of the input dimensions according to their relevance. They are adapted automatically during training according to the specific classification task whereby training can be interpreted as stochastic gradient descent on an appropriate error function. This method leads to a more powerful classifier and to an adaptive metric with little extra cost compared to standard GLVQ. Moreover, the size of the weighting factors indicates the relevance of the input dimensions. This proposes a scheme for automatically pruning irrelevant input dimensions. The algorithm is verified on artificial data sets and the iris data from the UCI repository. Afterwards, the method is compared to several well known algorithms which determine the intrinsic data dimension on real world satellite image data.

Algorithms↗

PubMedDate not supplied

Neural maps in remote sensing image analysis.

We study the application of self-organizing maps (SOMs) for the analyses of remote sensing spectral images. Advanced airborne and satellite-based imaging spectrometers produce very high-dimensional spectral signatures that provide key information to many scientific investigations about the surface and atmosphere of Earth and other planets. These new, sophisticated data demand new and advanced approaches to cluster detection, visualization, and supervised classification. In this article we concentrate on the issue of faithful topological mapping in order to avoid false interpretations of cluster maps created by an SOM. We describe several new extensions of the standard SOM, developed in the past few years: the growing SOM, magnification control, and generalized relevance learning vector quantization, and demonstrate their effect on both low-dimensional traditional multi-spectral imagery and approximately 200-dimensional hyperspectral imagery.

Image Processing, Computer-Assisted↗