Biomedical subjects

P Georgiewa

Publications and source records attributed to P Georgiewa.

4 recordsLinked to original sources

PubMed2005

[Integrated intensive treatment of tinnitus: method and initial results].

In recent years, no major advances have been made in understanding the mechanisms underlying the development of tinnitus. Hence, the present therapeutic strategies aim at decoupling the subconscious from the perception of tinnitus. Mindful of the lessons drawn from existing tinnitus retraining and desensitisation therapies, a new integrated day hospital strategy of treatment lasting 7-14 days has been developed at the Charité Hospital and is presented in the present paper. The strategy for treating tinnitus in the proximity of patient domicile is designed for patients who feel disturbed in their world of perception and their efficiency due to tinnitus and give evidence of mental and physical strain. In view of the etiologically non-uniform and multiple events connected with tinnitus, consideration was also given to the fact that somatic and psychosocial factors are equally involved. Therefore, therapy should aim at diagnosing and therapeutically influencing those psychosocial factors that reduce the hearing impression to such an extent that the affected persons suffer from strain. The first results of therapy-dependent changes of 46 patients suffering from chronic tinnitus are presented. The data were evaluated before and after 7 days of treatment and 6 months after the end of treatment. Immediately after the treatment, the scores of both the tinnitus questionnaire (Goebel and Hiller) and the subscales improved significantly. These results were maintained during the 6-month post-treatment period and even improved.

Adult↗

PubMed2005

Brain activation responses to subliminal or supraliminal rectal stimuli and to auditory stimuli in irritable bowel syndrome.

Visceral hypersensitivity in irritable bowel syndrome (IBS) has been associated with altered cerebral activations in response to visceral stimuli. It is unclear whether these processing alterations are specific for visceral sensation. In this study we aimed to determine by functional magnetic resonance imaging (fMRI) whether cerebral processing of supraliminal and subliminal rectal stimuli and of auditory stimuli is altered in IBS. In eight IBS patients and eight healthy controls, fMRI activations were recorded during auditory and rectal stimulation. Intensities of rectal balloon distension were adapted to the individual threshold of first perception (IPT): subliminal (IPT -10 mmHg), liminal (IPT), or supraliminal (IPT +10 mmHg). IBS patients relative to controls responded with lower activations of the prefrontal cortex (PFC) and anterior cingulate cortex (ACC) to both subliminal and supraliminal stimulation and with higher activation of the hippocampus (HC) to supraliminal stimulation. In IBS patients, not in controls, ACC and HC were also activated by auditory stimulation. In IBS patients, decreased ACC and PFC activation with subliminal and supraliminal rectal stimuli and increased HC activation with supraliminal stimuli suggest disturbances of the associative and emotional processing of visceral sensation. Hyperreactivity to auditory stimuli suggests that altered sensory processing in IBS may not be restricted to visceral sensation.

Acoustic Stimulation↗

PubMed2001

Pitfalls in the clustering of neuroimage data and improvements by global optimization strategies.

In this paper, we examined three vector quantization (VQ) methods used for the unsupervised classification (clustering) of functional magnetic resonance imaging (fMRI) data. Classification means that each brain volume element (voxel), according to a given scanning raster, was assigned to one group of voxels based on similarity of the fMRI signal patterns. It was investigated how the VQ methods can isolate a cluster that describes the region involved in a particular brain function. As an example, word processing was stimulated by a word comparison task. VQ analysis methodology was verified using simulated fMRI response patterns. It was demonstrated in detail that VQ based on global rather than local optimization of the objective function yielded a higher performance. Performance was measured in statistically relevant series of VQ attempts using several indices for goodness, reliability and efficiency of VQ solutions. Furthermore, it was shown that a poor local optimization caused either an underestimation or an overestimation of the stimulus-induced brain activation. However, this was not observed if the cluster analysis was based upon a global optimization strategy.

Adult↗

PubMed1999

fMRI during word processing in dyslexic and normal reading children.

The present study addresses phonological processing in children with developmental dyslexia. Following the hypothesis of a core deficit of assembled phonology in dyslexia a set of hierarchically structured tasks was applied that specifically control for different kinds of phonological coding (assembled versus addressed phonological strategies). Seventeen developmental dyslexics and 17 normal reading children were scanned during four different tasks: (1) passive viewing of letter strings (control condition), (2) passive reading of non-words, (3) passive reading of legal words, and (4) a task requiring phonological transformation. Statistical analysis of the data was performed using statistical parametric mapping (SPM96). Comparison of patterns of activation in dyslexic and normal reading children revealed significant differences in Broca's area and the left inferior temporal region for both, non-word reading and the phonological transformation task. The present data provide new evidence for alteration of the phonological system in dyslexic children, and in particular, the system that mediates assembled phonological coding.

Adolescent↗