The coordinated activity of hippocampal neurons is reflected by macroscopic patterns, theta and sharp waves (SPW), evident in extracellular field recordings. The importance of these patterns is underscored by the ordered relation of specific neuronal populations to each pattern as well as the relation of each pattern to distinct behavioral states. During awake immobility, consummatory behavior,...

BACKGROUND Among the various hippocampal network patterns, sharp wave-ripples (SPW-R) are currently the mechanistically least understood. Although accurate information on synaptic interactions between the participating neurons is essential for comprehensive understanding of the network function during complex activities like SPW-R, such knowledge is currently notably scarce. METHODOLOGY/PRINC...

Compared to steadily propagating waves (SPW), damped waves (DW), another solution to the nonlinear wave equation, are seldom studied. In cardiac tissue after electrical stimulation in an SPW wake, we observe DW with diminished amplitude and velocity that either gradually decrease as the DW dies, or exhibit a sharp amplitude increase after a delay to become an SPW. The cardiac DW-SPW transition ...

Sharp wave-ripple complexes (SPW-Rs) in the intact rodent hippocampus are characterized by slow field potential transients superimposed by close to 200-Hz ripple oscillations. Similar events have been recorded in hippocampal slices where SPW-Rs occur spontaneously or can be induced by repeated application of high-frequency stimulation, a standard protocol for induction of long-lasting long-term...

The mammalian hippocampus expresses several types of network oscillations which entrain neurons into transiently stable assemblies. These groups of co-active neurons are believed to support the formation, consolidation and recall of context-dependent memories. Formation of new assemblies occurs during theta- and gamma-oscillations under conditions of high cholinergic activity. Memory consolidat...

Hippocampal place field sequences are supported by sensory cues and network internal mechanisms. In contrast, sharp-wave (SPW) sequences, theta sequences, and episode field sequences are internally generated. The relationship of these sequences to memory is unclear. SPW sequences have been shown to support learning and have been assumed to also support episodic memory. Conversely, we demonstrat...

Hippocampal sharp wave-ripples (SPW-Rs) and associated place-cell reactivations are crucial for spatial memory consolidation during sleep and rest. However, it remains unclear how learning and consolidation requirements influence and regulate subsequent SPW-R activity. Indeed, SPW-R activity has been observed not only following complex behavioral tasks, but also after random foraging in familia...

AIM This prospective study was undertaken to evaluate whether stable patients with haemopericardium could safely be managed with subxiphoid pericardial window (SPW) and drainage only. PATIENTS AND METHODS From July to December 2001, all stable patients with haemopericardium diagnosed by SPW, who did not have immediate active bleeding, were subjected to sternotomy to grade the injury using the...

We show that for every separable Banach space X, either SPw(X) (the set of all spreading models of X generated by weakly-null sequences in X, modulo equivalence) is countable, or SPw(X) contains an antichain of the size of the continuum. This answers a question of S. J. Dilworth, E. Odell and B. Sari.

High-frequency oscillations, known as sharp-wave/ripple (SPW-R) complexes occurring in hippocampus during slow-wave sleep (SWS), have been proposed to promote synaptic plasticity necessary for memory consolidation. We recorded sleep for 3 h after rats were trained on an odor-reward association task. Learning resulted in an increased number SPW-Rs during the first hour of post-learning SWS. The ...