1
|
Alexander AS, Robinson JC, Stern CE, Hasselmo ME. Gated transformations from egocentric to allocentric reference frames involving retrosplenial cortex, entorhinal cortex, and hippocampus. Hippocampus 2023; 33:465-487. [PMID: 36861201 PMCID: PMC10403145 DOI: 10.1002/hipo.23513] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 01/22/2023] [Accepted: 01/25/2023] [Indexed: 03/03/2023]
Abstract
This paper reviews the recent experimental finding that neurons in behaving rodents show egocentric coding of the environment in a number of structures associated with the hippocampus. Many animals generating behavior on the basis of sensory input must deal with the transformation of coordinates from the egocentric position of sensory input relative to the animal, into an allocentric framework concerning the position of multiple goals and objects relative to each other in the environment. Neurons in retrosplenial cortex show egocentric coding of the position of boundaries in relation to an animal. These neuronal responses are discussed in relation to existing models of the transformation from egocentric to allocentric coordinates using gain fields and a new model proposing transformations of phase coding that differ from current models. The same type of transformations could allow hierarchical representations of complex scenes. The responses in rodents are also discussed in comparison to work on coordinate transformations in humans and non-human primates.
Collapse
Affiliation(s)
- Andrew S Alexander
- Center for Systems Neuroscience, Boston University, Boston, Massachusetts, USA
| | - Jennifer C Robinson
- Center for Systems Neuroscience, Boston University, Boston, Massachusetts, USA
| | - Chantal E Stern
- Center for Systems Neuroscience, Boston University, Boston, Massachusetts, USA
| | - Michael E Hasselmo
- Center for Systems Neuroscience, Boston University, Boston, Massachusetts, USA
| |
Collapse
|
2
|
Whittington JCR, Muller TH, Mark S, Chen G, Barry C, Burgess N, Behrens TEJ. The Tolman-Eichenbaum Machine: Unifying Space and Relational Memory through Generalization in the Hippocampal Formation. Cell 2020; 183:1249-1263.e23. [PMID: 33181068 PMCID: PMC7707106 DOI: 10.1016/j.cell.2020.10.024] [Citation(s) in RCA: 180] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 06/11/2020] [Accepted: 10/13/2020] [Indexed: 12/19/2022]
Abstract
The hippocampal-entorhinal system is important for spatial and relational memory tasks. We formally link these domains, provide a mechanistic understanding of the hippocampal role in generalization, and offer unifying principles underlying many entorhinal and hippocampal cell types. We propose medial entorhinal cells form a basis describing structural knowledge, and hippocampal cells link this basis with sensory representations. Adopting these principles, we introduce the Tolman-Eichenbaum machine (TEM). After learning, TEM entorhinal cells display diverse properties resembling apparently bespoke spatial responses, such as grid, band, border, and object-vector cells. TEM hippocampal cells include place and landmark cells that remap between environments. Crucially, TEM also aligns with empirically recorded representations in complex non-spatial tasks. TEM also generates predictions that hippocampal remapping is not random as previously believed; rather, structural knowledge is preserved across environments. We confirm this structural transfer over remapping in simultaneously recorded place and grid cells.
Collapse
Affiliation(s)
- James C R Whittington
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford OX3 9DU, UK.
| | - Timothy H Muller
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford OX3 9DU, UK; Institute of Neurology, UCL, London WC1N 3BG, UK
| | - Shirley Mark
- Wellcome Centre for Human Neuroimaging, UCL, London WC1N 3AR, UK
| | - Guifen Chen
- Institute of Cognitive Neuroscience, UCL, London WC1N 3AZ, UK; School of Biological and Chemical Sciences, QMUL, London E1 4NS, UK
| | - Caswell Barry
- Sainsbury Wellcome Centre for Neural Circuits and Behaviour, UCL, London W1T 4JG, UK; Research department of Cell and Developmental Biology, UCL, London WC1E 6BT, UK
| | - Neil Burgess
- Institute of Neurology, UCL, London WC1N 3BG, UK; Wellcome Centre for Human Neuroimaging, UCL, London WC1N 3AR, UK; Institute of Cognitive Neuroscience, UCL, London WC1N 3AZ, UK; Sainsbury Wellcome Centre for Neural Circuits and Behaviour, UCL, London W1T 4JG, UK
| | - Timothy E J Behrens
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford OX3 9DU, UK; Wellcome Centre for Human Neuroimaging, UCL, London WC1N 3AR, UK; Sainsbury Wellcome Centre for Neural Circuits and Behaviour, UCL, London W1T 4JG, UK
| |
Collapse
|
3
|
Alexander AS, Robinson JC, Dannenberg H, Kinsky NR, Levy SJ, Mau W, Chapman GW, Sullivan DW, Hasselmo ME. Neurophysiological coding of space and time in the hippocampus, entorhinal cortex, and retrosplenial cortex. Brain Neurosci Adv 2020; 4:2398212820972871. [PMID: 33294626 PMCID: PMC7708714 DOI: 10.1177/2398212820972871] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 10/21/2020] [Indexed: 11/18/2022] Open
Abstract
Neurophysiological recordings in behaving rodents demonstrate neuronal response properties that may code space and time for episodic memory and goal-directed behaviour. Here, we review recordings from hippocampus, entorhinal cortex, and retrosplenial cortex to address the problem of how neurons encode multiple overlapping spatiotemporal trajectories and disambiguate these for accurate memory-guided behaviour. The solution could involve neurons in the entorhinal cortex and hippocampus that show mixed selectivity, coding both time and location. Some grid cells and place cells that code space also respond selectively as time cells, allowing differentiation of time intervals when a rat runs in the same location during a delay period. Cells in these regions also develop new representations that differentially code the context of prior or future behaviour allowing disambiguation of overlapping trajectories. Spiking activity is also modulated by running speed and head direction, supporting the coding of episodic memory not as a series of snapshots but as a trajectory that can also be distinguished on the basis of speed and direction. Recent data also address the mechanisms by which sensory input could distinguish different spatial locations. Changes in firing rate reflect running speed on long but not short time intervals, and few cells code movement direction, arguing against path integration for coding location. Instead, new evidence for neural coding of environmental boundaries in egocentric coordinates fits with a modelling framework in which egocentric coding of barriers combined with head direction generates distinct allocentric coding of location. The egocentric input can be used both for coding the location of spatiotemporal trajectories and for retrieving specific viewpoints of the environment. Overall, these different patterns of neural activity can be used for encoding and disambiguation of prior episodic spatiotemporal trajectories or for planning of future goal-directed spatiotemporal trajectories.
Collapse
Affiliation(s)
| | | | | | | | - Samuel J. Levy
- Center for Systems Neuroscience, Boston University, Boston, MA, USA
| | - William Mau
- Center for Systems Neuroscience, Boston University, Boston, MA, USA
| | | | | | | |
Collapse
|
4
|
How the Internally Organized Direction Sense Is Used to Navigate. Neuron 2018; 101:285-293.e5. [PMID: 30522821 DOI: 10.1016/j.neuron.2018.11.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 09/12/2018] [Accepted: 11/08/2018] [Indexed: 11/21/2022]
Abstract
Head-direction cells preferentially discharge when the head points in a particular azimuthal direction, are hypothesized to collectively function as a single neural system for a unitary direction sense, and are believed to be essential for navigating extra-personal space by functioning like a compass. We tested these ideas by recording medial entorhinal cortex (MEC) head-direction cells while rats navigated on a familiar, continuously rotating disk that dissociates the environment into two spatial frames: one stationary and one rotating. Head-direction cells degraded directional tuning referenced to either of the externally referenced spatial frames, but firing rates, sub-second cell-pair action potential discharge relationships, and internally referenced directional tuning were preserved. MEC head-direction cell ensemble discharge collectively generates a subjective, internally referenced unitary representation of direction that, unlike a compass, is inconsistently registered to external landmarks during navigation. These findings indicate that MEC-based directional information is subjectively anchored, potentially providing for navigation without a stable externally anchored direction sense.
Collapse
|
5
|
Grid-Cell Activity on Linear Tracks Indicates Purely Translational Remapping of 2D Firing Patterns at Movement Turning Points. J Neurosci 2018; 38:7004-7011. [PMID: 29976622 DOI: 10.1523/jneurosci.0413-18.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 06/21/2018] [Accepted: 06/24/2018] [Indexed: 12/15/2022] Open
Abstract
Grid cells in rodent medial entorhinal cortex are thought to play a critical role for spatial navigation. When the animal is freely moving in an open arena the firing fields of each grid cell tend to form a hexagonal lattice spanning the environment. For movements along a linear track the cells seem to respond differently. They show multiple firing fields that are not periodically arranged and whose shape and position change when the running direction is reversed. In addition, peak firing rates vary widely from field to field. Measured along one running direction only, firing fields are, however, compatible with a slice through a two-dimensional (2D) hexagonal pattern. It is an open question, whether this is also true if leftward and rightward runs are jointly considered. By analyzing data from 15 male Long-Evans rats, we show that a single hexagonal firing pattern explains the linear-track data if translational shifts of the pattern are allowed at the movement turning points. A rotation or scaling of the grid is not required. The agreement is further improved if the peak firing rates of the underlying 2D grid fields can vary from field to field, as suggested by recent studies. These findings have direct consequences for experiments using linear tracks in virtual reality.SIGNIFICANCE STATEMENT Various types of neurons support spatial navigation. Their response properties are often studied in reduced settings and might change when the animal can freely explore its environment. Grid cells in rodents, for example, exhibit seemingly irregular firing fields when animal movement is restricted to a linear track but highly regular patterns in two-dimensional (2D) arenas. We show that linear-track responses of a cell for both leftward and rightward running directions can be explained as cuts through a single hexagonal pattern if translational remapping is allowed at movement turning points; neither rotations nor scale transformations are needed. These results provide a basis to quantify grid-cell activity in 1D virtual reality and could help to detect and categorize grid cells without experiments in 2D environments.
Collapse
|
6
|
Alexander AS, Nitz DA. Spatially Periodic Activation Patterns of Retrosplenial Cortex Encode Route Sub-spaces and Distance Traveled. Curr Biol 2017; 27:1551-1560.e4. [PMID: 28528904 DOI: 10.1016/j.cub.2017.04.036] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 04/03/2017] [Accepted: 04/19/2017] [Indexed: 10/19/2022]
Abstract
Traversal of a complicated route is often facilitated by considering it as a set of related sub-spaces. Such compartmentalization processes could occur within retrosplenial cortex, a structure whose neurons simultaneously encode position within routes and other spatial coordinate systems. Here, retrosplenial cortex neurons were recorded as rats traversed a track having recurrent structure at multiple scales. Consistent with a major role in compartmentalization of complex routes, individual retrosplenial cortex (RSC) neurons exhibited periodic activation patterns that repeated across route segments having the same shape. Concurrently, a larger population of RSC neurons exhibited single-cycle periodicity over the full route, effectively defining a framework for encoding of sub-route positions relative to the whole. The same population simultaneously provides a novel metric for distance from each route position to all others. Together, the findings implicate retrosplenial cortex in the extraction of path sub-spaces, the encoding of their spatial relationships to each other, and path integration.
Collapse
Affiliation(s)
- Andrew S Alexander
- Department of Cognitive Science, University of California, San Diego, La Jolla, CA 92092, USA
| | - Douglas A Nitz
- Department of Cognitive Science, University of California, San Diego, La Jolla, CA 92092, USA.
| |
Collapse
|
7
|
Savelli F, Luck JD, Knierim JJ. Framing of grid cells within and beyond navigation boundaries. eLife 2017; 6. [PMID: 28084992 PMCID: PMC5271608 DOI: 10.7554/elife.21354] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 01/11/2017] [Indexed: 12/21/2022] Open
Abstract
Grid cells represent an ideal candidate to investigate the allocentric determinants of the brain's cognitive map. Most studies of grid cells emphasized the roles of geometric boundaries within the navigational range of the animal. Behaviors such as novel route-taking between local environments indicate the presence of additional inputs from remote cues beyond the navigational borders. To investigate these influences, we recorded grid cells as rats explored an open-field platform in a room with salient, remote cues. The platform was rotated or translated relative to the room frame of reference. Although the local, geometric frame of reference often exerted the strongest control over the grids, the remote cues demonstrated a consistent, sometimes dominant, countervailing influence. Thus, grid cells are controlled by both local geometric boundaries and remote spatial cues, consistent with prior studies of hippocampal place cells and providing a rich representational repertoire to support complex navigational (and perhaps mnemonic) processes.
Collapse
Affiliation(s)
- Francesco Savelli
- Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, United States
| | - J D Luck
- Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, United States
| | - James J Knierim
- Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, United States.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, United States
| |
Collapse
|
8
|
Yoon K, Lewallen S, Kinkhabwala AA, Tank DW, Fiete IR. Grid Cell Responses in 1D Environments Assessed as Slices through a 2D Lattice. Neuron 2016; 89:1086-99. [PMID: 26898777 PMCID: PMC5507689 DOI: 10.1016/j.neuron.2016.01.039] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 11/30/2015] [Accepted: 01/13/2016] [Indexed: 12/13/2022]
Abstract
Grid cells, defined by their striking periodic spatial responses in open 2D arenas, appear to respond differently on 1D tracks: the multiple response fields are not periodically arranged, peak amplitudes vary across fields, and the mean spacing between fields is larger than in 2D environments. We ask whether such 1D responses are consistent with the system's 2D dynamics. Combining analytical and numerical methods, we show that the 1D responses of grid cells with stable 1D fields are consistent with a linear slice through a 2D triangular lattice. Further, the 1D responses of comodular cells are well described by parallel slices, and the offsets in the starting points of the 1D slices can predict the measured 2D relative spatial phase between the cells. From these results, we conclude that the 2D dynamics of these cells is preserved in 1D, suggesting a common computation during both types of navigation behavior.
Collapse
Affiliation(s)
- KiJung Yoon
- Center for Learning and Memory, University of Texas at Austin, Austin, TX 78712, USA; Department of Neuroscience, University of Texas at Austin, Austin, TX 78712, USA
| | - Sam Lewallen
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA; Bezos Center for Neural Circuit Dynamics and Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA
| | - Amina A Kinkhabwala
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA
| | - David W Tank
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA; Bezos Center for Neural Circuit Dynamics and Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA.
| | - Ila R Fiete
- Center for Learning and Memory, University of Texas at Austin, Austin, TX 78712, USA; Department of Neuroscience, University of Texas at Austin, Austin, TX 78712, USA.
| |
Collapse
|
9
|
Retrosplenial cortex maps the conjunction of internal and external spaces. Nat Neurosci 2015; 18:1143-51. [PMID: 26147532 DOI: 10.1038/nn.4058] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 06/10/2015] [Indexed: 12/16/2022]
Abstract
Intelligent behavior demands not only multiple forms of spatial representation, but also coordination among the brain regions mediating those representations. Retrosplenial cortex is densely interconnected with the majority of cortical and subcortical brain structures that register an animal's position in multiple internal and external spatial frames of reference. This unique anatomy suggests that it functions to integrate distinct forms of spatial information and provides an interface for transformations between them. Evidence for this was found in rats traversing two different routes placed at different environmental locations. Retrosplenial ensembles robustly encoded conjunctions of progress through the current route, position in the larger environment and the left versus right turning behavior of the animal. Thus, the retrosplenial cortex has the requisite dynamics to serve as an intermediary between brain regions generating different forms of spatial mapping, a result that is consistent with navigational and episodic memory impairments following damage to this region in humans.
Collapse
|
10
|
Raudies F, Brandon MP, Chapman GW, Hasselmo ME. Head direction is coded more strongly than movement direction in a population of entorhinal neurons. Brain Res 2014; 1621:355-67. [PMID: 25451111 DOI: 10.1016/j.brainres.2014.10.053] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 10/23/2014] [Accepted: 10/26/2014] [Indexed: 02/04/2023]
Abstract
The spatial firing pattern of entorhinal grid cells may be important for navigation. Many different computational models of grid cell firing use path integration based on movement direction and the associated movement speed to drive grid cells. However, the response of neurons to movement direction has rarely been tested, in contrast to multiple studies showing responses of neurons to head direction. Here, we analyzed the difference between head direction and movement direction during rat movement and analyzed cells recorded from entorhinal cortex for their tuning to movement direction. During foraging behavior, movement direction differs significantly from head direction. The analysis of neuron responses shows that only 5 out of 758 medial entorhinal cells show significant coding for both movement direction and head direction when evaluating periods of rat behavior with speeds above 10 cm/s and ±30° angular difference between movement and head direction. None of the cells coded movement direction alone. In contrast, 21 cells in this population coded only head direction during behavioral epochs with these constraints, indicating much stronger coding of head direction in this population. This suggests that the movement direction signal required by most grid cell models may arise from other brain structures than the medial entorhinal cortex. This article is part of a Special Issue entitled SI: Brain and Memory.
Collapse
Affiliation(s)
- Florian Raudies
- Center for Computational Neuroscience and Neural Technology, Boston University, 677 Beacon Street, Boston, MA 02115, USA; Center of Excellence for Learning in Education, Science, and Technology, Boston University, 677 Beacon Street, Boston, MA 02115, USA.
| | - Mark P Brandon
- Division of Biological Science, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093-0357, USA
| | - G William Chapman
- Department of Psychological and Brain Sciences, Center for Systems Neuroscience and Graduate Program for Neuroscience, Boston University, 2 Cummington Street, Boston, MA 02215, USA
| | - Michael E Hasselmo
- Center for Computational Neuroscience and Neural Technology, Boston University, 677 Beacon Street, Boston, MA 02115, USA; Center of Excellence for Learning in Education, Science, and Technology, Boston University, 677 Beacon Street, Boston, MA 02115, USA; Department of Psychological and Brain Sciences, Center for Systems Neuroscience and Graduate Program for Neuroscience, Boston University, 2 Cummington Street, Boston, MA 02215, USA
| |
Collapse
|
11
|
Yoder RM, Taube JS. The vestibular contribution to the head direction signal and navigation. Front Integr Neurosci 2014; 8:32. [PMID: 24795578 PMCID: PMC4001061 DOI: 10.3389/fnint.2014.00032] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 03/24/2014] [Indexed: 12/13/2022] Open
Abstract
Spatial learning and navigation depend on neural representations of location and direction within the environment. These representations, encoded by place cells and head direction (HD) cells, respectively, are dominantly controlled by visual cues, but require input from the vestibular system. Vestibular signals play an important role in forming spatial representations in both visual and non-visual environments, but the details of this vestibular contribution are not fully understood. Here, we review the role of the vestibular system in generating various spatial signals in rodents, focusing primarily on HD cells. We also examine the vestibular system's role in navigation and the possible pathways by which vestibular information is conveyed to higher navigation centers.
Collapse
Affiliation(s)
- Ryan M. Yoder
- Department of Psychology, Indiana University – Purdue University Fort WayneFort Wayne, IN, USA
| | - Jeffrey S. Taube
- Department of Psychological and Brain Sciences, Center for Cognitive Neuroscience, Dartmouth CollegeHanover, NH, USA
| |
Collapse
|
12
|
Brown TI, Hasselmo ME, Stern CE. A high-resolution study of hippocampal and medial temporal lobe correlates of spatial context and prospective overlapping route memory. Hippocampus 2014; 24:819-39. [PMID: 24659134 DOI: 10.1002/hipo.22273] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 03/06/2014] [Accepted: 03/20/2014] [Indexed: 11/05/2022]
Abstract
When navigating our world we often first plan or retrieve an ideal route to our goal, avoiding alternative paths that lead to other destinations. The medial temporal lobe (MTL) has been implicated in processing contextual information, sequence memory, and uniquely retrieving routes that overlap or "cross paths." However, the identity of subregions of the hippocampus and neighboring cortex that support these functions in humans remains unclear. The present study used high-resolution functional magnetic resonance imaging (hr-fMRI) in humans to test whether the CA3/DG hippocampal subfield and parahippocampal cortex are important for processing spatial context and route retrieval, and whether the CA1 subfield facilitates prospective planning of mazes that must be distinguished from alternative overlapping routes. During hr-fMRI scanning, participants navigated virtual mazes that were well-learned from prior training while also learning new mazes. Some routes learned during scanning shared hallways with those learned during pre-scan training, requiring participants to select between alternative paths. Critically, each maze began with a distinct spatial contextual Cue period. Our analysis targeted activity from the Cue period, during which participants identified the current navigational episode, facilitating retrieval of upcoming route components and distinguishing mazes that overlap. Results demonstrated that multiple MTL regions were predominantly active for the contextual Cue period of the task, with specific regions of CA3/DG, parahippocampal cortex, and perirhinal cortex being consistently recruited across trials for Cue periods of both novel and familiar mazes. During early trials of the task, both CA3/DG and CA1 were more active for overlapping than non-overlapping Cue periods. Trial-by-trial Cue period responses in CA1 tracked subsequent overlapping maze performance across runs. Together, our findings provide novel insight into the contributions of MTL subfields to processing spatial context and route retrieval, and support a prominent role for CA1 in distinguishing overlapping episodes during navigational "look-ahead" periods.
Collapse
Affiliation(s)
- Thackery I Brown
- Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts; Center for Memory and Brain, Boston University, Boston, Massachusetts; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts
| | | | | |
Collapse
|
13
|
Gupta K, Erdem UM, Hasselmo ME. Modeling of grid cell activity demonstrates in vivo entorhinal 'look-ahead' properties. Neuroscience 2013; 247:395-411. [PMID: 23660194 DOI: 10.1016/j.neuroscience.2013.04.056] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 04/25/2013] [Accepted: 04/26/2013] [Indexed: 11/29/2022]
Abstract
Recent in vivo data show ensemble activity in medial entorhinal neurons that demonstrates 'look-ahead' activity, decoding spatially to reward locations ahead of a rat deliberating at a choice point while performing a cued, appetitive T-Maze task. To model this experiment's look-ahead results, we adapted previous work that produced a model where scans along equally probable directions activated place cells, associated reward cells, grid cells, and persistent spiking cells along those trajectories. Such look-ahead activity may be a function of animals performing scans to reduce ambiguity while making decisions. In our updated model, look-ahead scans at the choice point can activate goal-associated reward and place cells, which indicate the direction the virtual rat should turn at the choice point. Hebbian associations between stimulus and reward cell layers are learned during training trials, and the reward and place layers are then used during testing to retrieve goal-associated cells based on cue presentation. This system creates representations of location and associated reward information based on only two inputs of heading and speed information which activate grid cell and place cell layers. We present spatial and temporal decoding of grid cell ensembles as rats are tested with perfect and imperfect stimuli. Here, the virtual rat reliably learns goal locations through training sessions and performs both biased and unbiased look-ahead scans at the choice point. Spatial and temporal decoding of simulated medial entorhinal activity indicates that ensembles are representing forward reward locations when the animal deliberates at the choice point, emulating in vivo results.
Collapse
Affiliation(s)
- K Gupta
- Center for Memory and Brain, Boston University, 2 Cummington Mall, Boston, MA 02215, USA.
| | | | | |
Collapse
|