The time course of pattern discrimination in the human brain.

In electrophysiological experiments on visual pattern discrimination, decision difficulty was manipulated either via the physical characteristics of the test stimuli, or by changing the instruction given to the observer. Visual stimuli were rectangular matrices each composed of 100 Gabor patches having different orientations. Matrices differed in the number of Gabor patches with vertical, or horizontal, orientation. The observers' task was either to discriminate the dominant orientation or to detect collinear elements in the matrix. Relating task difficulty to performance, in the first experimental paradigm (detection of orientation) we obtained the conventional S-like psychometric function but in the second (detection of collinearity) the psychometric function showed a complicated U-curve. Matching between electrophysiological and psychophysical data and image statistical functions allowed us to establish the relative timing of the cortical processes underlying perception and decision making in relation to textural features. In the first 170ms after stimulus onset coding of the low-level properties of the image takes place. In the time interval 170-400ms, ERP amplitude correlated only with complex image properties, but not with task difficulty. The first effects arising from decision difficulty were observable at 400ms after stimulus onset, and therefore this is probably the earliest electrophysiological signature of the decision making processes, in the given experimental paradigm.

Near-infrared dispersion and spin-orbit interaction of Co doped (80-x)Sb2O3-20Na2O-xWO3 glasses.

The present paper discusses the fact that the absorption spectra of doped with 0.1% Co3O4 glasses with the composition (80-x)Sb2O3-20Na2O-xWO3 are measured in the spectral region 1200-1400nm. The optical structure of Co(2+) is analyzed and the energies of the electron transitions in the metal ion are determined. The spin-orbit interaction is thoroughly analyzed. The refractive index n is calculated for the examined sample with x=20mol% WO3.

[Treatment of primary biliary cirrhosis with ursodeoxycholic acid]. / Lechenie na p'rvichnata biliarna tsiroza s urzodeoksikholeva kiselina.

This study was undertaken to evaluate the efficacy of ursodeoxycholic acid (UDCA) in the treatment of primary biliary cirrhosis (PBC). Three patients with PBC (stage II) have been treated with UDCA (Ursofalk and Falk Pharma, Freiburg, Germany)--of 10 mg/kg daily dosage in the course of three years. Patients with well-defined PBC underwent complete history, physical examination, liver chemistries, ultrasonography and liver biopsy. Liver chemistries were determined every three months. A control liver biopsy was performed to one of the patient, an year after the beginning of the treatment. UDCA was well tolerated and showed no side effects. The most obvious benefit of UDCA was its favourable effect on serum biochemistries. Its use was associated with the delayed progression of the disease.

[Assimilation of colostral immunoglobulins by calves]. / Usvoiavane na kolastralnite imunoglobulini pri teleta.

The utilization of colostral immunoglobulins was followed up in calves as dependent on the age of dams, the technology of raising and feeding, the season of calving, and the time of the first intake of colostrum after birth. The experiments were carried out with a total of 66 calves. Highest values of blood serum gammaglobulins were found at the 24th hour following birth. No essential differences were established in the utilization of immunoglobulins in dependence on the season. The delay in the first intake of colostrum after the sixth hour following birth led to lower absorption of the colostral immunoglobulins. Calves that were born by heifers remained with hypogammaglobulinemia over the entire period of investigation.