Medial entorhinal cortex

Learning enables animals to construct flexible knowledge structures, allowing them to adapt to new tasks by reconfiguring prior experiences into novel strategies. This compositional nature of learning suggests that fundamental building blocks from past experiences are essential for future problem-solving. To investigate how experience shapes learning, we trained Recurrent Neural Networks (RNNs) to model a complex, context-dependent odor timing task, using constraints derived from prior reports detailing mouse behavior and shaping procedures. The task, a temporal variant of the Delay Non-match

…shed light on how brain regions [e.g., medial entorhinal cortex (MEC), hippocampus] encode the self's position and trajectory. However, it has only recently been discovered that MEC and hippocampus are modulated by the positions and trajectories of others. To understand how encoding spatial information of multiple agents shapes neural representations, we train

Grid cells in the medial entorhinal cortex (MEC) of mammalian brains show hexagonal firing fields and are thought to encode the animal’s current location in the environment. As the animal moves, grid cells integrate self-motion cues to track the current position relative to a starting reference location. Recent experiments have identified a class of predictive grid cells that encode the animal’s upcoming location 1,2. Continuous attractor networks (CAN) explain how grid cells develop their characteristic hexagonal firing pattern and enable path integration. But how does predictive coding arise

How do neurons in the medial entorhinal cortex (MEC) organize themselves during development to establish networks involved in complex functions like learning and memory? From developmental studies of cortical and subcortical structures, one transcription factor called Bcl11b (encoding Ctip2) is responsible for neuronal differentiation and axonal pathfinding. Interestingly, in the MEC, Bcl11b is expressed by Reelin-positive (Reln+) projection neurons in layers 2 and by intracortical projection neurons in layer 5a . Because Bcl11b is widely expressed by these early born MEC neurons, we hypothesi

…dysfunction in the hippocampus and medial entorhinal cortex (MEC). However, aging-related changes in MEC at the cellular and molecular levels remain unclear. In this study, we found fewer grid cells with reduced spatial stability in old mice. We compared gene expression profiles between young and old mice using 10x Genomics Visium technology. Among 1664 differentially expressed genes, we discovered a marker gene for subpopulation in MEC Layer III with decreased cell number with age. Silen

…major spatial cortical input from the medial entorhinal cortex (MEC) via the perforant path. To determine whether inputs from the MEC (in particular layer II stellate cells) play a role in the capacity of the DG to differentiate between different environments, we aim to modulate their activity using DREADDs. Thanks to these pharmacogenetic tools, we can de- or hyper-polarize MEC-layer II stellate cells during e

…this map's construction, with the Medial Entorhinal Cortex (MEC) encoding self-motion cues (Path Integration) analogous to the 'where' pathway, while the Lateral Entorhinal Cortex (LEC) integrates sensory inputs analogous to the 'what' pathway. Object-dependent spatial cells, including Object Vector cells, Object Sensitive

The entorhinal cortex is a crucial hub for the coding of animals’ experiences in space. Grid cells, key components of this network, exhibit multiple firing fields that tessellate the environment as a function of the animals’ location. At the population level, the dynamics of the grid cell network reside on a toroidal manifold, irrespective of the sensory inputs or behavioral state, in agreement with continuous attractor networks (CAN) theories.However, the developmental origin of toroidal topology remains to be determined. Using Neuropixels 2.0 we obtained high-density population recordings in

The hippocampal-entorhinal circuit is part of a network of areas involved in the encoding and retrieval of representations of distinct spatial environments and episodes. We explored the complexity of neural activity patterns (‘dimensionality’), to understand how multiple maps are maintained in sub-populations of neurons. High dimensionality suggests unique neural 'maps' for different environments, while low dimensionality indicates overlapping representations across episodes. Prior research has shown distinct spatial representations in hippocampal subfields CA1/ CA3, with increased dimensional

Antibiotics are tremendously beneficial in reducing mortality rates by combating infections but their excessive use has led to severe antibiotic resistance worldwide. The ingestion of oral antibiotics dramatically alters the gut microbiome. Critically, there is limited understanding of the effects of a dysfunctional microbiome on brain function. Male C57BL/6J mice (2–4 months) were given drinking water containing antibiotics (ABX group; ampicillin, neomycin, gentamicin, metronidazole, and vancomycin) or untreated water (CON group). Separate cohorts received butyrate, a key microbiome-derived m

The entorhinal cortex is an area known to be involved in spatial navigation and episodic memories. While the spatial aspects of episodic memories have been studied in great detail, questions still remain regarding the processing of social information in the brain.Emerging evidence points towards a complex network of brain areas involved in social memory processing. In particular, the hippocampal regions CA2 and ventral CA1 play an important role, but the role of computations within the hippocampus compared to the input regions remains unresolved. With entorhinal cortex being the main input reg

The deep layers (V/VI) of the entorhinal cortex constitute a major relay station for routing neuronal activity from the hippocampus to downstream networks. To identify contributing pathways, we recently investigated the structural and functional organization of hippocampal projections to layer V (LV) of the medial entorhinal cortex (MEC) (Ohara, Rannap et al., Cell Rep. 2023). Here, we performed whole-cell patch-clamp recordings from MEC-LVI neurons combined with field potential recordings from hippocampal area CA1 in horizontal mouse brain slices. We found that a spontaneously occurring hippo

The grid cells in the entorhinal cortex play fundamental roles in spatial navigation. However, it has been unclear whether they contribute to predicting an animal’s future location or determining its future trajectory. In this study, we performed large-scale extracellular recordings from the medial entorhinal cortex together with hippocampal CA1 of rats moving toward a destination in the square arena. We found a subset of grid cells in the medial entorhinal cortex that represent grid fields when rate maps are estimated based on future animal locations, but these cells did not show grid field b

Grid cells of the medial entorhinal cortex (MEC) have been proposed to play a key role in navigation. Competing models suggest they contribute to spatial localisation in general or have a dedicated role in path integration. Here, we aim to distinguish these possibilities by investigating how grid and non-grid cell firing varies as a function of performance in a virtual reality location memory task that can be solved either with a cued-based strategy or exclusively by path integration. We take advantage of spontaneous variation within and between recording sessions, which gives a complementary

…epidural electrodes in the frontal cortex and depth electrodes in several temporal areas. Video-EEG recordings (24h, >3 days/week

…spatial information processing in the medial entorhinal cortex (MEC) of 18-month APP NL-G-F knock-in mice as they explored contextually novel and familiar open field arenas in a two-day, four-session recording paradigm. Using in vivo electrophysiology, we tracked single-units across all sessions and found that MEC single-unit spatial informatio

…of spatial information, arriving from medial entorhinal cortex (MEC), and object information, arriving from lateral entorhinal cortex (LEC), are integrated within the hippocampus. However, we recently discovered that fan cells in the LEC send direct projections to MEC, suggesting that spatial and object information could be integrated within MEC (Vandrey et al. 2022, doi:10.7554/eLife.83008). Evidence for object-related firing in the MEC is consistent with this possibility, but whether LEC projections influence spatial and obje

…The lateral entorhinal cortex may play a key role due its convergence of multisensory inputs, its encoding of events and their temporal relationships, and its connections with the hippocampal memory system. Here, we simultaneously recorded hundreds to thousands of neurons from lateral entorhinal cortex (LEC), media

What circuit mechanisms underlie the encoding and retrieval of spatial memory?In standard models, neurons have discrete fields that map onto locations, which are associated with actions. It is unclear if this feedforward mechanism is the only way in which spatial memories can be stored. Here, by reverse-engineering trained recurrent neural networks (RNNs) we identify alternative mechanisms for storage of location memories.We train RNNs on a spatial navigation task where an agent has to navigate to a hidden goal location. Reverse engineering these networks reveals their activity is similar to t

The study of rodent navigation has for decades focused on the hippocampal and parahippocampal regions, although recently part of this focus has shifted towards whether positional information can be identified in lower association cortices or even primary sensory areas. Spatial representation in these regions is often investigated using one-dimensional paradigms in combination with virtual reality. In the present work, we seek to understand how position is encoded in a more naturalistic, two-dimensional environment. Starting at the sensory level and moving up to higher association areas we aim

…Grid cells in the medial entorhinal cortex (MEC) are theta modulated during active wakefulness, with power and frequency correlating to e.g. running speed or environmental familiarity. Suppressin

The medial entorhinal cortex (MEC) forms a map of local space as well as local landmarks. This is achieved through canonical feature cells like grid, object vector, head direction and border cells that are located in the superficial layers of MEC but their exact anatomical organization remains to be determined. Previous work has shown that the grid cell network consists of discrete modules of increasing scale along the dorsal-ventral axis of MEC. In addition, recent imaging studies have hinted at a clustering of grid cells towards the medial part of MEC. However, due to technical limitations f

…Neural representations in the medial entorhinal cortex (MEC) constitute a generalized map of the local space, but recent findings may suggest that the MEC possesses non-spatial dimensions suggesting a generalized network for learning state spaces irrespectiv

The entorhinal cortex (EC) is central to the brain’s navigation system. Its subregions are conventionally thought to compute dichotomous representations for spatial processing: medial entorhinal cortex (MEC) provides a global spatial map, while lateral entorhinal cortex (LEC) encodes specific sensory details of experience. While local recordings of EC circuits have amassed a vast catalogue of specialized cell types that could support navigation computations in the brain, we have little direct evidence for how these signals are actually transmitted outside of the EC to its primary downstream re