Assessing the benefits of repeated esophagogastroduodenoscopy at a specialized center before gastric and esophageal cancer surgery.

Background: The surgical treatment of gastric and esophageal cancer in Denmark is centralized in four specialized esophagogastric cancer (EGC) centers. Patients are referred after an esophagogastroduodenoscopy (EGD) at a secondary healthcare facility. The EGD is repeated at the specialized EGC center before determining a surgical treatment strategy.

Learning exact enumeration and approximate estimation in deep neural network models.

A system for approximate number discrimination has been shown to arise in at least two types of hierarchical neural network models-a generative Deep Belief Network (DBN) and a Hierarchical Convolutional Neural Network (HCNN) trained to classify natural objects. Here, we investigate whether the same two network architectures can learn to recognise exact numerosity. A clear difference in performance could be traced to the specificity of the unit responses that emerged in the last hidden layer of each network.

Place cell rate remapping by CA3 recurrent collaterals.

Episodic-like memory is thought to be supported by attractor dynamics in the hippocampus. A possible neural substrate for this memory mechanism is rate remapping, in which the spatial map of place cells encodes contextual information through firing rate variability. To test whether memories are stored as multimodal attractors in populations of place cells, recent experiments morphed one familiar context into another while observing the responses of CA3 cell ensembles.

The entorhinal grid map is discretized.

The medial entorhinal cortex (MEC) is part of the brain's circuit for dynamic representation of self-location. The metric of this representation is provided by grid cells, cells with spatial firing fields that tile environments in a periodic hexagonal pattern. Limited anatomical sampling has obscured whether the grid system operates as a unified system or a conglomerate of independent modules.

Grid cells in pre- and parasubiculum.

Allocentric space is mapped by a widespread brain circuit of functionally specialized cell types located in interconnected subregions of the hippocampal-parahippocampal cortices. Little is known about the neural architectures required to express this variety of firing patterns. In rats, we found that one of the cell types, the grid cell, was abundant not only in medial entorhinal cortex (MEC), where it was first reported, but also in pre- and parasubiculum.

Representation of geometric borders in the entorhinal cortex.

We report the existence of an entorhinal cell type that fires when an animal is close to the borders of the proximal environment. The orientation-specific edge-apposing activity of these "border cells" is maintained when the environment is stretched and during testing in enclosures of different size and shape in different rooms. Border cells are relatively sparse, making up less than 10% of the local cell population, but can be found in all layers of the medial entorhinal cortex as well as the adjacent parasubiculum, often intermingled with head-direction cells and grid cells.

Progressive increase in grid scale from dorsal to ventral medial entorhinal cortex.

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 ventral parts of the medial entorhinal cortex, we recorded activity from entorhinal principal cells at multiple dorsoventral levels while rats shuttled back and forth on an 18 m long linear track.

Finite scale of spatial representation in the hippocampus.

To determine how spatial scale is represented in the pyramidal cell population of the hippocampus, we recorded neural activity at multiple longitudinal levels of this brain area while rats ran back and forth on an 18-meter-long linear track. CA3 cells had well-defined place fields at all levels. The scale of representation increased almost linearly from <1 meter at the dorsal pole to approximately 10 meters at the ventral pole.

From grid cells to place cells: a mathematical model.

Anatomical connectivity and recent neurophysiological results imply that grid cells in the medial entorhinal cortex are the principal cortical inputs to place cells in the hippocampus. The authors propose a model in which place fields of hippocampal pyramidal cells are formed by linear summation of appropriately weighted inputs from entorhinal grid cells. Single confined place fields could be formed by summing input from a modest number (10-50) of grid cells with relatively similar grid phases, diverse grid orientations, and a biologically plausible range of grid spacings.