Biomedical subjects

Bettina Sadowski

Publications and source records attributed to Bettina Sadowski.

4 recordsLinked to original sources

PubMed2004

Parietal somatosensory association cortex mediates affective blindsight.

To investigate the neural substrates underlying emotional feelings in the absence of a conscious stimulus percept, we presented a visual stimulus in the blind field of partially cortically blind patients and measured cortical activity (by functional magnetic resonance imaging, fMRI) before and after the stimulus had been paired with an aversive event. After pairing, self-reported negative emotional valence and blood oxygen level-dependent (BOLD) responses in somatosensory association areas were enhanced, whereby somatosensory activity predicted highly corresponding reported feelings and startle reflex amplitudes across subjects. Our data provide direct evidence that cortical activity representing physical emotional states governs emotional feelings.

Affective Symptoms↗

PubMed2004

Visual short-term effects of Viagra: double-blind study in healthy young subjects.

PURPOSE: To investigate short-term visual effects of a single 100-mg dose of Viagra (sildenafil citrate) in healthy men. DESIGN: Randomized, double-blind, placebo-controlled clinical trial of drug effects on normal volunteers conducted by a single center. METHODS: Twenty men, aged 20 to 40 years, were treated with either a placebo or 100 mg sildenafil. Visual function tests included electroretinogram (ERG) recordings, on-/off- and 3.3 Hz-flicker-ERG recordings, anomaloscope matches, and measurements of cone contrast sensitivities and transient tritanopia. RESULTS: Most visual tests did not differ between the sildenafil and placebo groups. However, statistically significant increases in sensitivity during transient tritanopia were observed as well as significant prolongations in the implicit times of scotopic a-wave, photopic b-wave, and 3.3 Hz-flicker a-wave and b-wave ERG recordings. The magnitude of the differences correlated with peak sidenafil plasma concentration. Although rod amplitudes of the ERG recordings tended to be higher and cone amplitudes lower in the sildenafil group after drug ingestion, the differences were nonsignificant. There were no reports of visual side effects, and all electrophysiologic and psychophysical measurements returned to the normal range within 24 hours. CONCLUSIONS: A single oral dose of 100-mg sildenafil given to healthy young men led to small but statistically significant transient changes of outer and inner retinal function, as detected by ERG and psychophysical methods. Although the acute effects were fully reversible within 24 hours, it would be worthwhile to compare them with those induced by other PDE5 and PDE6 inhibitors.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2003

Detecting color vision in a malingerer.

A patient describing himself as totally color blind was ordered by the judicial system to have his color vision investigated in order to establish his suitability for military service. Basic clinical (Farnsworth Panel D-15, Moreland and Rayleigh anomaloscope equations), electroretinographic (ERG) and psychophysical techniques (spectral sensitivities) were applied to determine the extent of his color discrimination performance and cone function. These standard procedures were complemented by a test for cone interaction (transient tritanopia) and by newly developed cone-isolating flicker large-field ERG recordings. The patient's data consistently indicate the function as well as the functional interaction of the middle-wavelength-sensitive (M-) and the short-wavelength-sensitive (S-) cones. But the function of the long-wavelength-sensitive (L-) cones was completely absent. Hence the patient was correctly demonstrated to be a protanope. This study establishes that standard classical procedures, in combination with newly developed and easy to apply psychophysical and ERG ones, which can be reliably used to assess true color discrimination performance, in difficult cases of malingering.

Adult↗

PubMed2002

Visual field constriction and electrophysiological changes associated with vigabatrin.

PURPOSE: We investigated functional, morphological and electrophysiological changes in patients under anti-epileptic therapy with vigabatrin (VGB), a GABA aminotransferase inhibitor. METHODS: 20 epileptic patients treated with vigabatrin (age range 25-66 years) were enrolled in this study. The referrals were made by the treating neurologist, based on suspected or known visual field changes in these patients. Two patients had vigabatrin monotherapy, 18 patients were treated with vigabatrin in combination with other antiepileptic drugs. None of the patients reported visual complaints. Patients were examined with psychophysical tests including colour vision (Farnsworth D15), dark adaptation threshold, Goldmann visual fields and Tuebingen Automated Perimetry (90 degrees). A Ganzfeld ERG and an EOG following the ISCEV standard protocol were also obtained. Additionally, all patients were examined with the VERIS multifocal ERG including recordings of multifocal oscillatory potentials. RESULTS: Visual acuity, anterior and posterior segments, colour vision and dark adaptation thresholds were normal in all patients. Of 20 patients, 18 presented visual field constriction. All patients with visual field defects revealed altered oscillatory potentials waveforms in the ERG, especially in those patients with marked visual field defects. Multifocal oscillatory potentials were also delayed in those patients. In some patients a delayed cone single flash response (6/20), a reduced mERG amplitude (12/20) and a reduced Arden ratio (9/20) were found. CONCLUSIONS: The present data indicate an effect of vigabatrin on the inner retinal layers. Since abnormalities of the oscillatory potentials were seen in all patients with visual field defects a dysfunction of GABA-ergic retinal cell transmission might be assumed.

Adult↗