Stimulus rivalry and binocular rivalry share a common neural substrate.

When two incompatible images are shown separately to each eye, a perceptual process known as binocular rivalry occurs by which the two images compete for awareness. The site of competition for binocular rivalry has been a topic of debate, and recent theories are that it may occur either at low levels of the visual system where the inputs from the two eyes are combined or at high levels of the visual system where the two images are processed. One of the major pieces of evidence for a high-level image account of rivalry is a phenomenon known as stimulus rivalry, in which two competing stimuli are swapped between the eyes at 3 Hz.

The influence of electric fields on hippocampal neural progenitor cells.

The differentiation and proliferation of neural stem/progenitor cells (NPCs) depend on various in vivo environmental factors or cues, which may include an endogenous electrical field (EF), as observed during nervous system development and repair. In this study, we investigate the morphologic, phenotypic, and mitotic alterations of adult hippocampal NPCs that occur when exposed to two EFs of estimated endogenous strengths. NPCs treated with a 437 mV/mm direct current (DC) EF aligned perpendicularly to the EF vector and had a greater tendency to differentiate into neurons, but not into oligodendrocytes or astrocytes, compared to controls.

Molecular characterization of penicillin-resistant Streptococcus pneumoniae isolates causing respiratory disease in the United States.

Three hundred twenty-eight (328) penicillin-resistant Streptococcus pneumoniae isolates collected in 39 states of the United States between October, 1996, and March, 1997, from (mostly adult) patients with respiratory disease were characterized by microbiological, serological, and molecular fingerprinting techniques, including determination of chromosomal macrorestriction pattern with pulsed-field gel electrophoresis (PFGE) and hybridization with DNA probes specific for various antibiotic resistance genes. The overwhelming majority of the isolates were in five serogroups (23, 6, 19, 9, 14). All isolates had penicillin MIC values of at least 2 microg/ml, but the collection also included isolates with MIC values as high as 16 microg/ml.

[Seasonal dynamics of the intercorrelations of the regulatory parameters of cardiac rhythm in irradiated rats].

A study of the structural and functional organization of cardiac rhythm in rats in various seasons of irradiation was carried out by the method of correlation analysis in the time course of radiation disease. Essential seasonal differences in the formation and value of correlation interconnections of cardiac rhythm parameters in rats, differing in the initial state of vegetative homeostasis were determined.