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Grid cell

Grid cells are a class of neurons found predominantly in the dorsocaudal medial entorhinal cortex (dMEC) of the mammalian brain, characterized by their periodic firing patterns that form a regular, hexagonal lattice across the environment traversed by the animal.^[1] These cells were discovered in 2005 by researchers Torkel Hafting, Marianne Fyhn, Sturla Molden, May-Britt Moser, and Edvard I. Moser through electrophysiological recordings in freely moving rats, revealing that individual grid cells activate at the vertices of equilateral triangles, creating a tessellating grid that scales with distance and orientation.^[1] The grids maintain consistent spacing and orientation across environments but can shift phase relative to landmarks, persisting even in the dark, which indicates their role in path integration for self-localization independent of visual cues.^[1]^[2] In collaboration with place cells—neurons in the hippocampus that fire at discrete locations to form a cognitive map of an environment—grid cells contribute to the brain's internal positioning system, often likened to a neural global positioning system (GPS).^[2] Place cells, first identified by John O'Keefe in 1971, provide location-specific signals, while grid cells supply a metric framework for distance and direction, enabling precise pathfinding and spatial memory formation.^[2] This integrated circuit is topographically organized, with grid field sizes and spacing increasing systematically from dorsal to ventral regions of the entorhinal cortex, suggesting a hierarchical representation of spatial scales.^[1] The discovery of grid cells, alongside place cells, earned May-Britt Moser and Edvard I. Moser the 2014 Nobel Prize in Physiology or Medicine (shared with O'Keefe) for elucidating the neural basis of spatial representation.^[2] Beyond rodents, evidence of grid-like activity has been observed in humans through functional neuroimaging and intracranial recordings during navigation tasks, implying conserved mechanisms across species for cognitive mapping.^[2] Disruptions in entorhinal grid cell function are implicated in spatial memory deficits seen in conditions like Alzheimer's disease, where early degeneration of the entorhinal cortex correlates with navigational impairments.^[2] Ongoing research explores how grid cells interact with head-direction cells and border cells to generate stable, flexible spatial representations, underscoring their foundational role in episodic memory and goal-directed behavior.^[1]

Discovery and Historical Context

Initial Discovery

Grid cells were first identified in 2005 by a team led by Edvard Moser and May-Britt Moser at the Norwegian University of Science and Technology, through electrophysiological recordings in the medial entorhinal cortex (MEC) of freely foraging rats.^[1] The researchers observed that certain neurons fired action potentials at multiple, regularly spaced locations as the rats explored a controlled environment, forming a lattice-like pattern distinct from previously known spatial cells.^[1] The experimental setup involved implanting tetrodes—bundles of four thin microwires—into the MEC of adult male Long-Evans rats, allowing simultaneous recording of multiple single units while the animals foraged for food pellets in a 1-meter-square black enclosure with white walls.^[1] These recordings captured the rats' head direction, position, and running speed using overhead video tracking, revealing that grid cells discharged in a periodic manner across the arena, with firing fields arranged in a hexagonal grid pattern.^[1] Each cell exhibited multiple firing fields, typically six or more, that tiled the entire environment without regard to physical boundaries or the location of rewards.^[1] This discovery built upon earlier findings of hippocampal place cells, which fire at specific locations but do not form such modular patterns, as reported by John O'Keefe in 1971.^[3] In their seminal paper published in Nature, Hafting et al. described the grid spacing as ranging from 30 to 60 cm between adjacent fields, with the grid's orientation consistently aligned to the enclosure's walls rather than the animal's movement direction.^[1] These initial observations established grid cells as a fundamental component of the brain's spatial representation system, providing a metric for distance and direction independent of sensory cues.^[1]

Key Milestones and Recognition

Following the initial observation of hexagonal firing patterns in rat entorhinal cortex, subsequent research from 2006 to 2010 confirmed grid cells in additional species, broadening their relevance across mammals. In 2008, grid cells were recorded in mice, enabling the use of genetic tools to probe their function. By 2011, grid cells were identified in the medial entorhinal cortex of bats, demonstrating similar spatial periodicity despite the absence of theta oscillations characteristic in rodents.^[4] During this era, studies revealed that grid cells form discrete modules in the entorhinal cortex, each with distinct spatial scales that increase progressively along the dorsoventral axis, providing a hierarchical representation of space. Concurrently, from 2005 to 2013, grid cells were integrated with other spatial cell types in the entorhinal cortex, including head direction cells that encode directional heading and conjunctive grid-by-head-direction cells that combine positional and orientational signals. Border cells, which fire near environmental boundaries, were discovered in 2008, further enriching the entorhinal network's role in defining spatial geometry. In 2013, intracranial recordings from human entorhinal cortex during virtual navigation tasks revealed neurons with grid-like firing patterns, suggesting conserved spatial coding mechanisms across primates. These cumulative discoveries culminated in the 2014 Nobel Prize in Physiology or Medicine, awarded to John O'Keefe, Edvard I. Moser, and May-Britt Moser for their work on place cells and grid cells that constitute the brain's positioning system.^[2]

Anatomical and Cellular Properties

Location and Morphology

Grid cells are primarily located in layer II of the medial entorhinal cortex (MEC) in mammals, where they form a key component of the spatial processing network.^[1] These neurons send excitatory projections to the dentate gyrus of the hippocampus via the perforant path, facilitating the transfer of spatial information to hippocampal circuits.^[5] Morphologically, the predominant cell type expressing grid properties in layer II is the stellate cell, which features a multipolar structure with fan-shaped dendritic arbors that radiate outward and span across cortical layers.^[6] In contrast, pyramidal cells in the same layer more often exhibit border or non-spatial firing, though a subset can display grid-like patterns; both pyramidal and stellate cells can exhibit grid properties, with studies varying on proportions.^[6]^[7] Fan cells, characterized by similar but less basal dendritic extent, are less common in the MEC and primarily identified in adjacent regions like the lateral entorhinal cortex.^[8] Layer-specific variations in grid cell types are evident across the MEC. In superficial layers II and III, principal grid cells dominate, firing in a purely spatial periodic manner without additional sensory tuning.^[1] Deeper layers V and VI, however, contain conjunctive grid cells that integrate grid periodicity with head-direction selectivity, reflecting a more multimodal anatomical organization.^[1] Grid cells are distributed in discrete modules along the dorsoventral axis of the MEC, with anatomical clustering of cells sharing similar grid orientations and scales within each module.^[9] The spatial scale of these grids progressively enlarges from dorsal to ventral regions, starting at approximately 40 cm spacing in the dorsal MEC and expanding to 2–4 meters in the ventral MEC, supporting a hierarchical representation of environmental scales.

Firing Patterns and Characteristics

Grid cells, located in the medial entorhinal cortex (MEC), exhibit a distinctive spatial firing pattern characterized by periodic activation at the vertices of a triangular lattice, which manifests as a hexagonal grid when viewed in two dimensions. This geometry arises as an animal navigates an open environment, with the cell firing when the animal's position coincides with the grid nodes, spaced at regular intervals and exhibiting 60-degree rotational symmetry. The hexagonal arrangement provides an efficient tiling of space, allowing a single cell to represent multiple locations across the environment through its repeating fields.^[1] The scale of the grid, defined by the distance between adjacent firing fields, varies across the population of grid cells, typically ranging from approximately 25 cm in dorsal MEC to over 300 cm in more ventral regions. Grid cells are organized into discrete modules, where cells within a module share similar scales and orientations, with successive modules exhibiting commensurate increases in spacing by a factor of about 1.4. Orientations of the grid axes are often aligned across modules within an individual animal, clustering around a preferred angle offset from environmental boundaries to optimize spatial resolution, though modules can occasionally exhibit independent rotations.^[10] These firing patterns demonstrate remarkable stability over time and across different recording sessions in familiar environments, maintaining consistent scale, phase, and orientation to support reliable spatial mapping. However, distortions occur in non-square enclosures or when barriers alter the geometry, leading to shearing of the lattice into elliptical shapes and correlated rotations of the grid axes aligned with the environmental boundaries. Such adaptability ensures the grid remains anchored to salient features while preserving its periodic structure. A subset of grid cells display conjunctive properties, integrating spatial information with other signals such that firing is modulated not only by position but also by head direction or running speed. For instance, conjunctive grid-by-head-direction cells fire at specific grid locations only when the animal faces particular directions, while others scale their response rate with velocity to facilitate path integration. These hybrid representations enhance the grid system's utility in dynamic navigation.

Neural Interactions

With Hippocampal Place Cells

Grid cells in the medial entorhinal cortex (MEC) project monosynaptically to hippocampal pyramidal cells in CA1 and CA3 via the perforant path, providing a direct excitatory input that links entorhinal spatial representations to hippocampal ones. Layer II MEC neurons, which include the majority of grid cells, primarily target the dentate gyrus and CA3, while layer III projections reach CA1, enabling both direct and trisynaptic influences on place cell activity.^[11] These connections form the anatomical basis for the integration of grid cell periodic firing patterns into the more localized firing of hippocampal place cells. Hippocampal place fields emerge from the combinatorial convergence of inputs from multiple grid cell modules with varying spatial scales and phases, which generates single-peaked fields from the superposition of multiple periodic inputs.^[12] This mechanism enhances place cell stability by providing a consistent metric framework across environments and contributes to remapping dynamics, where changes in grid cell activity can shift or resize place fields without requiring complete reconfiguration.^[13] The offset firing phases among grid cells from different modules ensure that their overlapping activity creates discrete locations, explaining the higher resolution and sparsity of place cell representations compared to individual grid patterns.^[14] In novel environments, grid cells typically exhibit rate remapping, characterized by changes in firing rates while maintaining spatial structure, whereas hippocampal place cells undergo global remapping with entirely new field locations. This distinction was demonstrated in experiments where subtle environmental changes, such as cue modifications, induced partial rate adjustments in grid cells that predicted the extent of place cell remapping, linking entorhinal stability to hippocampal flexibility.^[15] Resizing experiments further highlight these differences: when environments were expanded, grid cell fields scaled accordingly with rate changes, but place cells remapped globally, underscoring the role of grid inputs in modulating but not fully determining place field reconfiguration.^[16] Computational simulations support this integration, showing that feedforward inputs from multiple grid modules to place cells produce stable, Gaussian-like place fields with resolutions finer than those of individual grids, due to the interference patterns formed by phase offsets.^[17] These models demonstrate how grid cell combinatorics can account for place field properties, including their stability in familiar spaces and sensitivity to novelty, without invoking additional sensory inputs.^[18]

With Other Spatial Cells

Grid cells in the medial entorhinal cortex (MEC) interact extensively with other spatial cell types within the local circuitry, forming conjunctive representations that integrate multiple spatial signals. Conjunctive grid-by-head direction cells, found in deeper layers (III, V, and VI) of the MEC, fire selectively at specific grid field locations only when the animal faces a particular direction, combining positional periodicity with directional tuning. These cells co-activate with head direction cells to provide a directional modulation of grid firing, enabling the computation of vector-based path integration. The modular organization of grid cells, characterized by discrete clusters with distinct spatial scales, facilitates interactions with speed cells that convey velocity information essential for updating grid positions during movement. Speed cells in the MEC modulate their firing rates linearly with running speed, providing excitatory input to grid cells across modules to support path integration; this interaction is evident in conjunctive firing patterns observed during novel tasks, where velocity signals help adapt grid alignments to unfamiliar environments. Such modular coupling ensures that velocity-modulated updates propagate across scales, maintaining coherent spatial metrics even in dynamic or novel contexts.^[19] Reciprocal connections between the MEC and the parasubiculum play a critical role in head direction tuning for grid cells, stabilizing grid orientations through bidirectional signaling. The parasubiculum, rich in head direction cells, projects to superficial layers of the MEC, providing directional input that influences grid cell activity, while feedback from the MEC refines parasubicular tuning via layered projections. This network feedback loop helps anchor grid patterns to allocentric reference frames, preventing drift in orientation during navigation.^[20] Interactions across dorsoventral modules of the MEC enable multi-scale integration, where dorsal modules with small-scale grids interface with ventral modules featuring larger scales to form hierarchical spatial codes. These inter-module connections allow fine-grained local representations to inform broader, abstract mappings, supporting the integration of local and global spatial information within the entorhinal network.^[21]

Oscillatory and Temporal Dynamics

Theta Rhythmicity

Grid cells in the medial entorhinal cortex exhibit strong synchronization with hippocampal theta oscillations, which occur at frequencies of 4-12 Hz during active locomotion in rodents. This theta rhythmicity manifests as phase-locked spiking, where grid cell action potentials are preferentially timed to specific phases of the theta cycle, ensuring that firing bursts align with the oscillatory cycles of the local field potential. Such locking is observed in nearly all principal neurons in layer II of the medial entorhinal cortex, highlighting the integral role of theta in modulating grid cell activity. The modulation of grid cell firing by theta is closely tied to the animal's velocity. As running speed increases, grid cell firing rates rise proportionally, with spikes peaking during particular theta cycles that correspond to the downward phase of the oscillation. Despite this temporal modulation, the underlying spatial periodicity of grid firing fields remains consistent across different theta phases, preserving the hexagonal lattice structure independent of the oscillation's timing. This velocity-dependent enhancement of firing supports the integration of speed signals into the spatial code without altering the geometric organization. Cross-frequency coupling between grid cells and theta oscillations involves progressive shifts in the preferred firing phase relative to the theta cycle as the animal traverses space. Specifically, the theta phase at which grid cells fire advances systematically with the distance traveled through a firing field, mirroring a similar mechanism observed in hippocampal place cells and facilitating temporal coding of position updates. This coupling underscores the shared oscillatory framework linking entorhinal and hippocampal representations. Experimental evidence for theta rhythmicity in grid cells was first demonstrated through extracellular recordings in freely foraging rats, revealing robust phase-locking to theta oscillations in the medial entorhinal cortex as early as 2008 by the Moser laboratory. More recent studies using optogenetic techniques to disrupt theta generation—such as silencing medial septal GABAergic neurons, which drive hippocampal theta—have shown that such interventions destabilize grid cell periodicity and phase relationships, confirming the necessity of intact theta rhythms for stable grid firing patterns. These findings establish theta synchronization as a critical temporal scaffold for grid cell function.

Phase Precession

Phase precession in grid cells refers to the phenomenon where, as a rodent traverses a firing field, the neuron's action potentials occur at progressively earlier phases of the local theta rhythm in successive cycles. This temporal shift begins near the end of the theta cycle upon entering the field and advances by up to a full 360 degrees by the time the animal exits, providing a compressed representation of position within the field.^[22] Unlike hippocampal place cells, which exhibit phase precession confined to a single firing field, grid cell precession extends across multiple fields along a trajectory, allowing for finer-grained temporal coding of extended spatial paths and providing 80% more spatial information than firing rates alone, improving the accuracy of positional estimates from 9.3 cm to 5.8 cm (using spike counts versus phases, respectively).^[23] Electrophysiological recordings demonstrate that the rate of phase precession in grid cells is proportional to the animal's running speed, with steeper phase slopes observed during faster traversals, consistent with velocity-modulated input dynamics. Computational models attribute this precession to asymmetric recurrent connectivity in continuous attractor networks, where directional biases in synaptic weights generate oscillatory shifts in activity bumps relative to theta inputs.^[24]^[25] This phase coding mechanism supports the replay of spatial trajectories during rest or sharp-wave ripple events, enabling the prediction and consolidation of sequential experiences by reactivating compressed representations of past paths.^[26]

Computational Models

Attractor-Based Models

Attractor-based models propose that grid cell firing arises from continuous attractor dynamics within networks of neurons in the medial entorhinal cortex (MEC), where stable activity patterns, or "bumps," represent spatial positions through recurrent excitatory-inhibitory interactions. These models, inspired by earlier work on path integration, simulate hexagonal grid patterns by arranging neurons on a two-dimensional sheet with symmetric, locally connected weights that promote cooperation among nearby cells and competition among distant ones, forming a lattice of activity bumps.^[27] A key feature is the integration of self-motion cues to update the position of these activity bumps, enabling path integration. In these models, the bump position is updated based on velocity vectors from the animal's movement. Stability of the hexagonal firing is maintained through symmetric weight matrices that ensure multiple equivalent stable states, with noise facilitating transitions and preventing trapping in metastable configurations.^[27] Simulations of these ring attractor networks demonstrate their ability to produce observed grid cell properties, such as spatial scale gradients across MEC modules, achieved through variations in network connectivity parameters that produce larger grid spacings in ventral regions. The models also predict independence between modules, allowing selective disruptions in one without affecting others, and have been tested against environmental distortions like barriers, where partial resets of activity bumps lead to grid realignments that mimic empirical remapping behaviors.^[27]

Grid Formation Theories

One prominent alternative to attractor-based mechanisms for grid cell formation is the oscillatory interference (OI) model, which posits that grid-like firing patterns arise from the superposition of multiple velocity-modulated oscillatory inputs within individual grid cells. In this framework, proposed by Burgess et al. in 2007, each grid cell receives inputs from velocity-controlled oscillators (VCOs) tuned to different spatial scales and orientations; the interference beats between these oscillations produce periodic firing fields that form a hexagonal lattice when multiple frequencies are involved. The model's core idea is that self-motion signals, such as speed and direction, modulate the frequencies of these oscillations, enabling path integration without requiring network-level interactions.^[28] Mathematically, the firing rate in the OI model can be approximated as the sum of cosine functions representing the oscillatory inputs:

f(x, y) = \sum_{n} \cos\left(2\pi f_n (x \cos \alpha + y \sin \alpha) + \phi_n \right)

where f_n are the frequencies of the oscillators (scaled by velocity), \alpha is the orientation of the input, and \phi_n are phase offsets; the superposition generates hexagonal firing patterns due to the beat frequencies aligning at lattice points. This single-cell mechanism contrasts with population-based attractors by emphasizing intrinsic dendritic computations and has been supported by predictions matching theta phase effects in grid firing.^[28] Another class of models relies on Hebbian learning principles to achieve self-organization of grid patterns from unstructured or place-like inputs. In these approaches, synaptic plasticity rules, such as spike-timing-dependent plasticity (STDP), strengthen connections between pre- and post-synaptic neurons based on correlated activity during spatial exploration, gradually refining inputs into periodic grids. A biologically plausible implementation by Widloski and Fiete in 2014 demonstrates that asymmetric STDP acting on initially random place cell-like inputs can produce stable hexagonal grids, with the process driven by the animal's movement statistics and competitive inhibition. These models highlight how unsupervised learning could bootstrap grid formation in development or across environments. Hybrid models integrate elements of oscillatory interference with attractor dynamics to enhance robustness against noise and disruptions. For instance, Couey et al. in 2014 proposed a framework where OI provides initial velocity-tuned inputs that are stabilized by recurrent connectivity in a continuous attractor network, allowing grids to persist despite partial input loss. Empirical support for such integration comes from genetic manipulations; selective knockout of NMDA receptors in the medial entorhinal cortex disrupts grid periodicity and impairs path integration in mice, suggesting that both oscillatory inputs and network stabilization are necessary for maintaining grid integrity. More recent models, such as unified frameworks integrating oscillatory and attractor dynamics (e.g., Wulf et al., 2022), and advanced learning algorithms, continue to refine these theories, addressing robustness and developmental aspects.^[29]

Functions in Cognition

Grid cells in the medial entorhinal cortex play a central role in path integration, a process of dead-reckoning that allows animals to estimate their position by continuously accumulating self-motion cues such as velocity and acceleration. This odometric function is supported by the periodic firing patterns of grid cells, which integrate velocity inputs over time to update an internal representation of location without relying on external visual landmarks. However, to prevent error accumulation, these grid-based signals require periodic resetting through interactions with environmental landmarks.^[30] Experimental evidence demonstrates that grid cell firing persists in complete darkness, indicating reliance on idiothetic (self-motion) cues for maintaining spatial periodicity during navigation. In such conditions, grid cells continue to exhibit stable firing patterns for extended periods, underscoring their contribution to path integration independent of visual input. Furthermore, in virtual reality environments where spatial distortions are introduced, alterations in grid cell firing regularity have been shown to correlate with behavioral errors in path estimation, as observed in rats navigating manipulated layouts.^[30]^[31] Grid cells are organized into discrete modules characterized by distinct spatial scales, enabling the encoding of metric distances across varying ranges during movement. Smaller-scale modules provide fine-grained resolution for short distances, while larger-scale modules support broader spatial tracking, collectively facilitating accurate distance estimation in path integration tasks. A 2025 study in mice revealed that grid cell activity dynamically tracks accumulated displacement during path integration by reanchoring to landmarks, with temporal firing patterns enabling path decoding despite absent stable grid fields.^[32]^[33] Despite their utility, path integration via grid cells is prone to accumulating errors from noisy velocity signals, necessitating anchoring to stable environmental cues provided by hippocampal place cells to recalibrate the grid network and maintain navigational accuracy.

Metric and Cognitive Mapping

Grid cells extend beyond basic spatial navigation to form the basis of cognitive maps that represent abstract domains such as sequences, time, and social relationships. In humans, functional magnetic resonance imaging (fMRI) studies have revealed grid-like representations in the entorhinal cortex during tasks involving navigation through social spaces, where participants evaluated relationships between fictional characters based on traits like trustworthiness and competence. These representations exhibit hexagonal symmetry similar to spatial grids, suggesting that grid cells provide a metric structure for organizing and navigating non-physical cognitive spaces.^[34] Recent findings indicate that grid cell activity does not rely on a single global map but instead forms multiple local modular maps, allowing for flexible and context-dependent spatial representations. In rodent experiments, grid cells were observed to decorrelate positions across different environments, functioning like a locality-sensitive hashing system that scrambles long-range distances while preserving local structure; this modularity enables rapid remapping without disrupting overall navigation. Such local maps facilitate adaptation to novel contexts by maintaining distinct modules for different spatial scales or environments.^[35] Grid cells also contribute to episodic memory formation by integrating with hippocampal schemas to bind events into coherent representations. Computational models suggest that entorhinal ring attractors, involving grid cell networks, cooperate with hippocampal place cells to stabilize episodic traces, allowing the binding of contextual elements like location, time, and objects into lasting memories. This integration supports the schema-based organization of experiences, where grid-like codes provide a stable scaffold for event sequencing and retrieval.^[36] In non-spatial cognition, grid-like codes analogously support numerical processing and planning by imposing a structured metric on ordered abstract spaces. Human entorhinal activity shows grid-like patterns when navigating mental number lines or temporal sequences, enabling efficient representation of magnitude and order in numerical cognition. Similarly, during goal-directed planning, grid cells in the entorhinal cortex exhibit goal-attracted distortions, biasing representations toward prospective outcomes to facilitate decision-making in cognitive maps.^[37]^[38]

Evidence in Humans and Recent Advances

Human Grid-Like Activity

The first direct evidence for grid-like activity in humans came from intracranial electroencephalography (iEEG) recordings in epilepsy patients undergoing surgical evaluation. In a 2013 study, Jacobs et al. recorded from electrodes implanted in the entorhinal cortex of seven patients navigating a virtual reality environment. They identified multi-unit activity exhibiting hexagonal modulation, with firing rates peaking at regular intervals forming a triangular lattice, analogous to the periodic firing patterns of rodent grid cells. This activity was tuned to the patient's virtual position and orientation, providing the initial invasive demonstration of grid-like representations in the human brain.^[39] Non-invasive imaging techniques have since corroborated these findings, revealing grid-like signals in the entorhinal cortex during spatial tasks. Using functional magnetic resonance imaging (fMRI), Bellmund et al. (2016) observed periodic, six-fold symmetric BOLD responses in the entorhinal region of healthy participants imagining navigation through a virtual environment, consistent with grid cell population codes. Complementary intracranial electroencephalography (iEEG) studies have detected grid-like modulation of theta-band oscillations in the entorhinal cortex during virtual navigation, with power varying hexagonally as a function of heading direction. Additionally, fMRI evidence shows spatial scale gradients across the entorhinal cortex, where anterior regions respond to finer spatial resolutions and posterior regions to coarser ones, mirroring the modular organization seen in rodents.^[40]^[41]^[42] Task-specific paradigms have further elucidated grid-like signals in contexts involving path integration. In a 2022 study, entorhinal recordings and imaging during virtual reality tasks demonstrated that grid-like codes track self-motion cues for path integration, enabling estimation of displacement without visual landmarks. More recently, a 2025 investigation in Current Biology examined distortions of grid patterns in polarized room environments using electrophysiology in rats and behavioral measures in humans. In rats, warped hexagonal grid signals in the entorhinal cortex correlated with errors in distance estimation during path integration tasks, and humans showed similar behavioral errors in asymmetric spaces. These findings highlight how environmental geometry influences grid stability and path integration accuracy across species.^[43] Compared to rodents, human grid-like activity exhibits weaker spatial selectivity, with signals often less sharply tuned to precise locations and more susceptible to modulation by cognitive factors such as attention and mental simulation. This suggests a more abstract, flexible role in human spatial cognition, integrating sensory and internal states beyond pure metric navigation.^[44]

Developments Since 2020

Since 2020, research on grid cells has revealed their modular organization, with evidence indicating that entorhinal grid cells form multiple local maps rather than a single global system, enabling environment-specific remapping and flexible spatial navigation. A 2025 study recording from over 10 grid cells in freely moving mice demonstrated that these cells dynamically shift their reference frames based on recent experiences, such as reanchoring to local landmarks like a lever or doorway, which supports adaptation to changing contexts without relying on a fixed universal map.^[33]^[45] Advances in understanding path integration have shown that grid cells accurately track self-motion during navigation, even amid reference frame switches, contributing to precise homing behavior. In a 2025 Nature Neuroscience study, grid cell activity in mice performing a path integration task in darkness predicted movement trajectories with high fidelity, as decoded by deep-learning algorithms, despite the absence of stable hexagonal patterns and the presence of orientation drift.^[33] Additionally, grid cell distortions in polarized environments, such as trapezoids, correlate with increased distance estimation errors in both rats and humans, with reduced grid regularity (measured by gridness scores) linking to overestimated path lengths, highlighting the cells' role in metric accuracy.^[43] In humans, hippocampal ripples have been found to integrate new experiences into a grid-like schema, facilitating schema-based inference. A 2025 Neuron study using intracranial recordings from epilepsy patients showed that ripple activity during post-learning rest predicted the emergence of grid-like codes in the entorhinal cortex and medial prefrontal cortex, enabling inference of unseen relational patterns in a conceptual 2D space, with ripples synchronizing experiences to this schema rather than direct retrieval.^[46]^[47] Entorhinal grid cell modules exhibit functional independence, driving remapping in hippocampal place cells and supporting switches between egocentric and allocentric navigation. A 2025 bioRxiv preprint demonstrated that independent realignment of grid modules during environmental changes coincides with global place cell remapping, allowing adaptive spatial representations without coordinated module shifts.^[48] Complementing this, recordings from mice navigating mazes revealed grid cells rapidly switching from egocentric (self-motion-based) to allocentric (landmark-based) frames within seconds, functioning as a local positioning system that adapts to internal or external cues for targeted homing.^[33]^[49] Broader insights from 2024 highlight convergent evolution between biological grid cells and artificial systems in brain-machine interfaces, where hexagonal grid patterns parallel compression algorithms like JPEG basis functions for efficient spatial coding. This parallelism, with high correlations (r = 0.94) between neural and artificial relational encodings, underscores how grid-like mechanisms optimize information processing across natural and engineered networks.^[50]^[51]

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Grid cells are organised into modules: Cells from the same module share the orientation and scale parameter but differ in their spatial phase (top, shades of ...
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Grid cells accurately track movement during path integration-based ...
Sep 10, 2025 · It is widely assumed that grid cells encode movement in a single, global reference frame. In this study, by recording grid cell activity in mice ...
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Not a global map, but a local hash: grid cells decorrelate ... - bioRxiv
Sep 20, 2025 · Here we combine modeling with analyses of neural population data from mice and rats to show that the grid cell representation is ideally set up ...
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Episodic Memories: How do the Hippocampus and the Entorhinal ...
The brain is capable of registering a constellation of events, encountered only once, as an episodic memory that can last for a lifetime.Missing: schema | Show results with:schema
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Navigating cognition: Spatial codes for human thinking - Science
Nov 9, 2018 · However, grid-like coding in three dimensions remains elusive, as does evidence for spatial coding in cognitive spaces of higher dimensionality.Navigating Cognition... · A Continuous Map Of... · Multiple Scales Of Coding
[35]
The entorhinal cognitive map is attracted to goals - Science
Mar 29, 2019 · Grid cells with their rigid hexagonal firing fields are thought to provide an invariant metric to the hippocampal cognitive map, ...
[36]
Direct recordings of grid-like neuronal activity in human spatial ...
We identified cells exhibiting grid-like spiking patterns in the human brain, suggesting that humans and simpler animals rely on homologous spatial-coding ...
[37]
Grid-cell representations in mental simulation - eLife
Aug 30, 2016 · The computations of these cells might contribute to other kinds of thinking too, such as remembering the past or imagining future events.
[38]
Grid-cell representations in mental simulation - PubMed
Aug 30, 2016 · Grid-like representations have been observed in the human entorhinal cortex during virtual and imagined navigation. However, hitherto it ...Missing: et | Show results with:et
[39]
Grid-like hexadirectional modulation of human entorhinal theta ... - NIH
Oct 3, 2018 · The entorhinal cortex plays a critical role in allowing organisms to navigate and represent spatial memories using grid-like representations ...Results · Fig. 1 · Fig. 4
[40]
Are Grid-Like Representations a Component of All Perception and ...
Jul 13, 2022 · Grid codes may be able to generalize experiences and make appropriate decisions in novel conditions to accommodate behavioral flexibility (Yu et ...Missing: numerical | Show results with:numerical
[41]
Grid cells create multiple local maps rather than single global ...
Oct 20, 2025 · Grid cells create multiple local maps rather than single global system for spatial navigation, study finds. by Ingrid Fadelli, Medical Xpress.
[42]
https://pmc.ncbi.nlm.nih.gov/articles/PMC6196498/
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Human hippocampal ripples align new experiences with a grid-like ...
Aug 22, 2025 · These findings show that hippocampal ripples align new experiences with an existing grid-like schema, transforming discrete events into ...
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[45]
Functional independence of entorhinal grid cell modules enables ...
Sep 24, 2025 · A key distinction is that neural activity in MEC, including that of directionally tuned cells and grid cells, evolves along low-dimensional ...
[46]
No GPS in the head: How the brain flexibly switches between ...
Sep 24, 2025 · Our data show that grid cells function more like a local positioning system than a GPS," explains co-study leader Allen. In addition, the ...
[47]
Brain–machine convergent evolution: Why finding parallels between ...
Oct 2, 2024 · Here we propose that finding parallels between artificial and neuronal networks is informative precisely because these systems are so different from each other.
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https://www.biorxiv.org/content/10.1101/2025.09.24.677985v1