Network architecture underlying maximal separation of neuronal representations.

One of the most basic and general tasks faced by all nervous systems is extracting relevant information from the organism's surrounding world. While physical signals available to sensory systems are often continuous, variable, overlapping, and noisy, high-level neuronal representations used for decision-making tend to be discrete, specific, invariant, and highly separable. This study addresses the question of how neuronal specificity is generated.

A simple connectivity scheme for sparse coding in an olfactory system.

Recent studies, using unbiased sampling of neuronal activity in vivo, indicate the existence of sparse codes in the brain. These codes are characterized by highly specific, associative (i.e.

Mitral annulus calcification with a mobile component as a possible source of embolism.

Mitral annulus calcification has been associated with embolic events, but the precise pathophysiology has not been elucidated. The authors describe four patients who experienced embolic events whose transesophageal echocardiograms showed a mitral annulus calcification, with a mobile component that exhibited the same echogenicity as the calcification. Three patients had no other conditions known to be associated with embolism.

Thrombosis of bileaflet tricuspid valve prosthesis: clinical spectrum and the role of nonsurgical treatment.

Background: Thrombosis of a mechanical tricuspid valve prosthesis is a potentially hazardous event. This study aimed to explore the incidence and the clinical presentation of tricuspid valve thrombosis occurring in bileaflet valves and to evaluate the diagnostic and the therapeutic approach.

Methods And Results: Tricuspid valve thrombosis was sought in 22 late survivors with the CarboMedics valve in a follow-up period of 36.

Association between mitral annular calcium and aortic atheroma as detected by transesophageal echocardiographic study.

Significant association was found between the presence of mitral annular calcium (MAC) and aortic atheroma detected by transesophageal echocardiography. MAC may be an important marker for aortic atherosclerosis.