The hippocampal formation plays key roles in representing an animal's location and in detecting environmental novelty to create or update those representations. However, the mechanisms behind this latter function are unclear. Here, we show that environmental novelty causes the spatial firing patterns of grid cells to expand in scale and reduce in regularity, reverting to their familiar scale as...

The hippocampal cognitive map is thought to be driven by distal visual cues and self-motion cues. However, other sensory cues also influence place cells. Hence, we measured rat hippocampal activity in virtual reality (VR), where only distal visual and nonvestibular self-motion cues provided spatial information, and in the real world (RW). In VR, place cells showed robust spatial selectivity; ho...

Every permutation of {1, 2, . . . , N} can be written as the product of two involutions. As a consequence, any permutation of the elements of an array can be performed in-place using simultaneous swaps in two rounds of swaps. In the case where the permutation is the k-way perfect shuffle we develop two methods for efficiently computing the pair of involutions that accomplishes these swaps. The ...

We recorded hippocampal place cells in two spatial environments: a training environment in which rats underwent fear conditioning and a neutral control environment. Fear conditioning caused many place cells to alter (or remap) their preferred firing locations in the training environment, whereas most cells remained stable in the control environment. This finding indicates that aversive reinforc...

To elucidate how gaze informs the construction of mental space during wayfinding in visual species like primates, we jointly examined navigation behavior, visual exploration, and hippocampal activity as macaque monkeys searched a virtual reality maze for a reward. Cells sensitive to place also responded to one or more variables like head direction, point of gaze, or task context. Many cells fir...

Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague 4, Czech Republic, Department of Mathematics, Rostov State University, R. Zorge 5, 344090 Rostov-on-Don, Russian Federation Department of Physiology and Pharmacology, State University of New York, Downstate Medical Center, 450 Clarkson Ave., Brooklyn, NY 11203, USA {aolypher, lansky, fenton}@biomed....

The effect of synaptic inhibition on burst firing of a two-compartment model of a CA3 pyramidal cell is considered. We show that, depending on its timing, a short dose of fast decaying synaptic inhibition can either delay or advance the timing of firing of subsequent bursts. Moreover, increasing the strength of the inhibitory input is shown to modulate the burst profile from a full complex burs...

The extent of external and internal factors contributing to location-specific firing of hippocampal place cells is currently unclear. We investigated the role of active movement in location-specific firing by comparing spatial firing patterns of hippocampal neurons, while rats either ran freely or rode a motorized cart on the same circular track. Most neurons changed their spatial firing patter...

This paper analyzes the diversification-value puzzle from the Real Options (RO) approach. Our proposal conceives corporate diversification as a process which involves both the sequential replacement of prior acquired investment opportunities by assets-in-place and the generation of new valuable growth options. We argue that this conceptual framework allows to explain both documented diversifica...

In 1971, John O’Keefe and Jonathan Dostrovsky discovered place cells, and the hippocampal world has not been the same since. In the nearly 30 years since that discovery, hundreds of studies have been published, and thousands of words have been written, yet full understanding of the function of these cells and the role they collectively play in the hippocampus, remains somewhat elusive. The coll...