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The ability to find one's way depends on neural algorithms that integrate information about place, distance and direction, but the implementation of these operations in cortical microcircuits is poorly understood. Here we show that the dorsocaudal medial entorhinal cortex (dMEC) contains a directionally oriented, topographically organized neural map of the(More)
Grid cells in the medial entorhinal cortex (MEC) are part of an environment-independent spatial coordinate system. To determine how information about location, direction, and distance is integrated in the grid-cell network, we recorded from each principal cell layer of MEC in rats that explored two-dimensional environments. Whereas layer II was predominated(More)
Gamma oscillations are thought to transiently link distributed cell assemblies that are processing related information, a function that is probably important for network processes such as perception, attentional selection and memory. This 'binding' mechanism requires that spatially distributed cells fire together with millisecond range precision; however,(More)
Grid cells are topographically organized in the sense that, within the dorsal part of the medial entorhinal cortex, the scale of the grid increases systematically with anatomical distance from the dorsal border of this brain area. The ventral limit of the spatial map is currently not known. To determine if the grid map extends into the intermediate and(More)
Theta-phase precession in hippocampal place cells is one of the best-studied experimental models of temporal coding in the brain. Theta-phase precession is a change in spike timing in which the place cell fires at progressively earlier phases of the extracellular theta rhythm as the animal crosses the spatially restricted firing field of the neuron. Within(More)
As the interface between hippocampus and neocortex, the entorhinal cortex is likely to play a pivotal role in memory. To determine how information is represented in this area, we measured spatial modulation of neural activity in layers of medial entorhinal cortex projecting to the hippocampus. Close to the postrhinal-entorhinal border, entorhinal neurons(More)
A fundamental property of many associative memory networks is the ability to decorrelate overlapping input patterns before information is stored. In the hippocampus, this neuronal pattern separation is expressed as the tendency of ensembles of place cells to undergo extensive 'remapping' in response to changes in the sensory or motivational inputs to the(More)
To determine whether entorhinal spatial representations are continuous or fragmented, we recorded neural activity in grid cells while rats ran through a stack of interconnected, zig-zagged compartments of equal shape and orientation (a hairpin maze). The distribution of spatial firing fields was markedly similar across all compartments in which running(More)
To determine how hippocampal backprojections influence spatially periodic firing in grid cells, we recorded neural activity in the medial entorhinal cortex (MEC) of rats after temporary inactivation of the hippocampus. We report two major changes in entorhinal grid cells. First, hippocampal inactivation gradually and selectively extinguished the grid(More)
The medial entorhinal cortex (EC) is a part of the neural network for the representation of self-location in the rat. The key cell type of this system is the grid cell, whose multiple firing fields span the environment in a remarkably regular triangular or hexagonal pattern. The basic properties of grid cells and other cell types have been described, but(More)