Propagation of sharp wave-ripple activity in the mouse hippocampal CA3 subfield in vitro.

Sharp wave-ripple complexes (SPW-Rs) are spontaneous oscillatory events that characterize hippocampal activity during resting periods and slow-wave sleep. SPW-Rs are related to memory consolidation - the process during which newly acquired memories are transformed into long-lasting memory traces. To test the involvement of SPW-Rs in this process, it is crucial to understand how SPW-Rs originate and propagate throughout the hippocampus.

Intra-ripple frequency accommodation in an inhibitory network model for hippocampal ripple oscillations.

Hippocampal ripple oscillations have been implicated in important cognitive functions such as memory consolidation and planning. Multiple computational models have been proposed to explain the emergence of ripple oscillations, relying either on excitation or inhibition as the main pacemaker. Nevertheless, the generating mechanism of ripples remains unclear.

Transformation of the head-direction signal into a spatial code.

Animals integrate multiple sensory inputs to successfully navigate in their environments. Head direction (HD), boundary vector, grid and place cells in the entorhinal-hippocampal network form the brain's navigational system that allows to identify the animal's current location, but how the functions of these specialized neuron types are acquired remain to be understood. Here we report that activity of HD neurons is influenced by the ambulatory constraints imposed upon the animal by the boundaries of the explored environment, leading to spurious spatial information.

The transformation from grid cells to place cells is robust to noise in the grid pattern.

Spatial navigation in rodents has been attributed to place-selective cells in the hippocampus and entorhinal cortex. However, there is currently no consensus on the neural mechanisms that generate the place-selective activity in hippocampal place cells or entorhinal grid cells. Given the massive input connections from the superficial layers of the entorhinal cortex to place cells in the hippocampal cornu ammonis (CA) regions, it was initially postulated that grid cells drive the spatial responses of place cells.