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The spatial responses of many of the cells recorded in all layers of rodent medial entorhinal cortex (mEC) show mutually aligned grid patterns. Recent experimental findings have shown that grids can often be better described as elliptical rather than purely circular and that, beyond the mutual alignment of their grid axes, ellipses tend to also orient their(More)
We follow up on a suggestion by Rolls and co-workers, that the effects of competitive learning should be assessed on the shape and number of spatial fields that dentate gyrus (DG) granule cells may form when receiving input from medial entorhinal cortex (mEC) grid units. We consider a simple non-dynamical model where DG units are described by a(More)
One obstacle to understanding the exact processes unfolding inside the hippocampus is that it is still difficult to clearly define what the hippocampus actually does, at the system level. Associated for a long time with the formation of episodic and semantic memories, and with their temporary storage, the hippocampus is also regarded as a structure involved(More)
We introduce gain-based policies for exploration in active learning problems. For exploration in multi-armed bandits with the knowledge of reward variances, an ideal gain-maximization exploration policy is described in a unified framework which also includes error-based and counter-based exploration. For realistic situations without prior knowledge of(More)
The multiple layers of medial entorhinal cortex (mEC) contain cells that differ in selectivity, connectivity, and cellular properties. Grid cells in layer II and in the deeper layers express triangular grid patterns in the environment. The firing rate of the conjunctive cells found in layer III and below, on the other hand, show grid-by-head direction(More)
Localization, mapping and action selection are three main aspects in robot exploration. This paper proposes an autonomous exploration method for robot localization and mapping in unknown environments. First an ideal global-probabilistic measure, which we call objective objective function, is introduced to evaluate the objective exploration performance. By(More)
The spatial responses of many of the cells recorded in layer II of rodent medial entorhinal cortex (MEC) show a triangular grid pattern, which appears to provide an accurate population code for animal spatial position. In layer III, V and VI of the rat MEC, grid cells are also selective to head-direction and are modulated by the speed of the animal. Several(More)
A local-autoencoding (LAE) method is proposed for the parameter estimation in a Hidden Potts-Markov random field model. Due to sampling cost, Markov chain Monte Carlo methods are rarely used in real-time applications. Like other heuristic methods, LAE is based on a conditional independence assumption. It adapts, however, the parameters in a block-by-block(More)
The entorhino-hippocampal neural circuits of the mammalian brains are able to internally generate efficient spatial representations of large-scale environments. Hippocampal principal cells in mammalian brains form sparse codes of the positions in large environments. The underlying computational mechanisms of the formation of spatial memory in large-scale(More)