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Neil Burgess - One of the best experts on this subject based on the ideXlab platform.
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Ripple Band Phase Precession of Place Cell Firing during Replay
2021Co-Authors: Daniel Bush, Caswell Barry, F. Olafsdottir, Neil BurgessAbstract:Phase coding offers several theoretical advantages for information transmission compared to an equivalent rate code. Phase coding is shown by Place Cells in the rodent hippocampal formation, which fire at progressively earlier phases of the movement related 6-12Hz theta rhythm as their spatial receptive fields are traversed. Importantly, however, phase coding is independent of carrier frequency, and so we asked whether it might also be exhibited by Place Cells during 150-250Hz ripple band activity, when they are thought to replay information to neocortex. We demonstrate that Place Cells which fire multiple spikes during candidate replay events do so at progressively earlier ripple phases, and that spikes fired across all replay events exhibit a negative relationship between decoded location within the firing field and ripple phase. These results provide insights into the mechanisms underlying phase coding and Place Cell replay, as well as the neural code propagated to downstream neurons.
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what do grid Cells contribute to Place Cell firing
Trends in Neurosciences, 2014Co-Authors: Neil Burgess, Daniel Bush, Caswell BarryAbstract:The unitary firing fields of hippocampal Place Cells are commonly assumed to be generated by input from entorhinal grid Cell modules with differing spatial scales. Here, we review recent research that brings this assumption into doubt. Instead, we propose that Place Cell spatial firing patterns are determined by environmental sensory inputs, including those representing the distance and direction to environmental boundaries, while grid Cells provide a complementary self-motion related input that contributes to maintaining Place Cell firing. In this view, grid and Place Cell firing patterns are not successive stages of a processing hierarchy, but complementary and interacting representations that work in combination to support the reliable coding of large-scale space.
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The boundary vector Cell model of Place Cell firing and spatial memory
REV NEUROSCIENCE, 2006Co-Authors: Neil BurgessAbstract:We review evidence for the boundary vector Cell model of the environmental determinants of the firing of hippocampal Place Cells. Preliminary experimental results are presented concerning the effects of addition or removal of environmental boundaries on Place Cell firing and evidence that boundary vector Cells may exist in the subiculum. We review and update computational simulations predicting the location of human search within a virtual environment of variable geometry, assuming that boundary vector Cells provide one of the input representations of location used in mammalian spatial memory. Finally, we extend the model to include experience-dependent modification of connection strengths through a BCM-like learning rule - the size and sign of strength change is influenced by historic activity of the postsynaptic Cell. Simulations are compared to experimental data on the firing of Place Cells under geometrical manipulations to their environment. The relationship between neurophysiological results in rats and spatial behaviour in humans is discussed.
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the boundary vector Cell model of Place Cell firing and spatial memory
Reviews in The Neurosciences, 2006Co-Authors: Caswell Barry, Robin Hayman, Stephen Burton, Colin Lever, John Okeefe, Tom Hartley, Kate Jeffery, Neil BurgessAbstract:We review evidence for the boundary vector Cell model of the environmental determinants of the firing of hippocampal Place Cells. Preliminary experimental results are presented concerning the effects of addition or removal of environmental boundaries on Place Cell firing and evidence that boundary vector Cells may exist in the subiculum. We review and update computational simulations predicting the location of human search within a virtual environment of variable geometry, assuming that boundary vector Cells provide one of the input representations of location used in mammalian spatial memory. Finally, we extend the model to include experience-dependent modification of connection strengths through a BCM-like learning rule, and compare the effects to experimental data on the firing of Place Cells under geometrical manipulations to their environment. The relationship between neurophysiological results in rats and spatial behaviour in humans is discussed.
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long term plasticity in hippocampal Place Cell representation of environmental geometry
Nature, 2002Co-Authors: Colin Lever, Francesca Cacucci, Thomas J Wills, Neil Burgess, John OkeefeAbstract:The hippocampus is widely believed to be involved in the storage or consolidation of long-term memories. Several reports have shown short-term changes in single hippocampal unit activity during memory and plasticity experiments, but there has been no experimental demonstration of long-term persistent changes in neuronal activity in any region except primary cortical areas. Here we report that, in rats repeatedly exposed to two differently shaped environments, the hippocampal-Place-Cell representations of those environments gradually and incrementally diverge; this divergence is specific to environmental shape, occurs independently of explicit reward, persists for periods of at least one month, and transfers to new enclosures of the same shape. These results indicate that Place Cells may be a neural substrate for long-term incidental learning, and demonstrate the long-term stability of an experience-dependent firing pattern in the hippocampal formation.
Bruno Poucet - One of the best experts on this subject based on the ideXlab platform.
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Medial entorhinal cortex lesions induce degradation of CA1 Place Cell firing stability when self-motion information is used
Brain and Neuroscience Advances, 2020Co-Authors: Pierre-yves Jacob, Tiffany Van Cauter, Bruno Poucet, Francesca Sargolini, Etienne SaveAbstract:The entorhinal–hippocampus network plays a central role in navigation and episodic memory formation. To investigate these interactions, we examined the effect of medial entorhinal cortex lesions on hippocampal Place Cell activity. Since the medial entorhinal cortex is suggested to play a role in the processing of self-motion information, we hypothesised that such processing would be necessary for maintaining stable Place fields in the absence of environmental cues. Place Cells were recorded as medial entorhinal cortex–lesioned rats explored a circular arena during five 16-min sessions comprising a baseline session with all sensory inputs available followed by four sessions during which environmental (i.e. visual, olfactory, tactile) cues were progressively reduced to the point that animals could rely exclusively on self-motion cues to maintain stable Place fields. We found that Place field stability and a number of Place Cell firing properties were affected by medial entorhinal cortex lesions in the baseline session. When rats were forced to rely exclusively on self-motion cues, within-session Place field stability was dramatically decreased in medial entorhinal cortex rats relative to SHAM rats. These results support a major role of the medial entorhinal cortex in processing self-motion cues, with this information being conveyed to the hippocampus to help anchor and maintain a stable spatial representation during movement.
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Prefrontal Cortex Focally Modulates Hippocampal Place Cell Firing Patterns
Journal of Neuroscience, 2013Co-Authors: Vincent Hok, Etienne Save, Ehsan Chah, Bruno PoucetAbstract:Previous work shows that medial prefrontal cortex (mPFC) Cells exhibit spatio-selective activity at a goal location when rats are trained in a goal-oriented navigation task. Damaging the ventral and intermediate hippocampal regions severely disrupts both mPFC goal firing and behavioral performance in the same task. Additionally, hippocampal Place Cells tend to develop a secondary Place field at the goal location, suggesting that goal locations can be encoded by local changes in firing rate, within an otherwise stable spatial representation. Therefore, it has been suggested that the coordinated activity of a large fraction of hippocampal Cells at the goal location may interact with the mPFC to compute accurate planning trajectories, relying on both precise location-specific firing of Place Cells and the coarse-coded, goal-trajectory planning function of the prefrontal cortex. To test this hypothesis, we inactivated the mPFC and recorded hippocampal Place Cell activity while animals were performing the navigation task. The results show that post-training inactivation of the prefrontal cortex does not affect behavioral performance, suggesting that this structure is no longer required when animals are overtrained. The goal-related activity of Place Cells was not affected at either single unit or local field potential level. Conversely, profound modifications of Place Cell firing variability (overdispersion) were observed after suppression of prefrontal input, suggesting a possible mechanism underlying behavioral flexibility.
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Local remapping of Place Cell firing in the Tolman detour task.
European Journal of Neuroscience, 2011Co-Authors: Alice Alvernhe, Etienne Save, Bruno PoucetAbstract:The existence of Place Cells, whose discharge is strongly related to a rat’s location in its environment, has led to the proposal that they form part of an integrated neural system dedicated to spatial navigation. It has been suggested that this system could represent space as a cognitive map, which is flexibly used by animals to plan new shortcuts or efficient detours. To further understand the relationships between hippocampal Place Cell firing and cognitive maps, we examined the discharge of Place Cells as rats were exposed to a Tolman-type detour problem. In specific sessions, a transparent barrier was Placed onto the maze so as to block the shortest central path between the two rewarded end locations of a familiar three-way maze. We found that rats rapidly and consistently chose the shortest alternative detour. Furthermore, both CA1 and CA3 Place Cells that had a field in the vicinity of the barrier displayed local remapping. In contrast, neither CA1 nor CA3 Cells that had a field away from the barrier were affected. This finding, at odds with our previous report of altered CA3 discharge for distant fields in a shortcut task, suggests that the availability of a novel path and the blocking of a familiar path are not equivalent and could lead to different responses of the CA3 Place Cell population. Together, the two studies point to a specific role of CA3 in the representation of spatial connectivity and sequences.
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attention like modulation of hippocampus Place Cell discharge
The Journal of Neuroscience, 2010Co-Authors: André A. Fenton, Larissa Zinyuk, William W Lytton, Jeremy M Barry, Pierrepascal Lencksantini, Stepan Kubik, J Bures, Bruno PoucetAbstract:Hippocampus Place Cell discharge is an important model system for understanding cognition, but evidence is missing that the Place code is under the kind of dynamic attentional control characterized in primates as selective activation of one neural representation and suppression of another, competing representation. We investigated the apparent noise (“overdispersion”) in the CA1 Place code, hypothesizing that overdispersion results from discharge fluctuations as spatial attention alternates between distal cues and local/self-motion cues. The hypothesis predicts that: (1) preferential use of distal cues will decrease overdispersion; (2) global, attention-like states can be decoded from ensemble discharge such that both the discharge rates and the spatial firing patterns of individual Cells will be distinct in the two states; (3) identifying attention-like states improves reconstructions of the rat9s path from ensemble discharge. These predictions were confirmed, implying that a covert, dynamic attention-like process modulates discharge on a ∼1 s time scale. We conclude the hippocampus Place code is a dynamic representation of the spatial information in the immediate focus of attention.
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Impaired long term stability of CA1 Place Cell representation in mice lacking the transcription factor zif268/egr1.
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Sophie Renaudineau, Bruno Poucet, Serge Laroche, Sabrina Davis, Etienne SaveAbstract:Zif268 is a transcriptional regulator that plays a crucial role in maintenance of the late phases of hippocampal long-term potentiation (LTP) and consolidation of spatial memories. Because the hippocampal Place Cell system is essential for long-term spatial memory, we tested the hypothesis that zif268 is required for long-term stability of hippocampal Place Cell representations by recording CA1 Place Cells in mice lacking zif268. We found that zif268 gene deletion destabilized the representation of a familiar environment after exposure to a novel environment and impaired the long-term (24 h), but not short-term (1 h), stability of newly formed representations. These impairments could be rescued by repeated exposure to the novel environment, however. These results indicate that zif268 contributes to the long-term stability of spatial representations in CA1 and support the notion that the long-term stability of Place Cell representations requires transcription-dependent mechanisms similar to those observed in LTP.
Etienne Save - One of the best experts on this subject based on the ideXlab platform.
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Medial entorhinal cortex lesions induce degradation of CA1 Place Cell firing stability when self-motion information is used
Brain and Neuroscience Advances, 2020Co-Authors: Pierre-yves Jacob, Tiffany Van Cauter, Bruno Poucet, Francesca Sargolini, Etienne SaveAbstract:The entorhinal–hippocampus network plays a central role in navigation and episodic memory formation. To investigate these interactions, we examined the effect of medial entorhinal cortex lesions on hippocampal Place Cell activity. Since the medial entorhinal cortex is suggested to play a role in the processing of self-motion information, we hypothesised that such processing would be necessary for maintaining stable Place fields in the absence of environmental cues. Place Cells were recorded as medial entorhinal cortex–lesioned rats explored a circular arena during five 16-min sessions comprising a baseline session with all sensory inputs available followed by four sessions during which environmental (i.e. visual, olfactory, tactile) cues were progressively reduced to the point that animals could rely exclusively on self-motion cues to maintain stable Place fields. We found that Place field stability and a number of Place Cell firing properties were affected by medial entorhinal cortex lesions in the baseline session. When rats were forced to rely exclusively on self-motion cues, within-session Place field stability was dramatically decreased in medial entorhinal cortex rats relative to SHAM rats. These results support a major role of the medial entorhinal cortex in processing self-motion cues, with this information being conveyed to the hippocampus to help anchor and maintain a stable spatial representation during movement.
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Prefrontal Cortex Focally Modulates Hippocampal Place Cell Firing Patterns
Journal of Neuroscience, 2013Co-Authors: Vincent Hok, Etienne Save, Ehsan Chah, Bruno PoucetAbstract:Previous work shows that medial prefrontal cortex (mPFC) Cells exhibit spatio-selective activity at a goal location when rats are trained in a goal-oriented navigation task. Damaging the ventral and intermediate hippocampal regions severely disrupts both mPFC goal firing and behavioral performance in the same task. Additionally, hippocampal Place Cells tend to develop a secondary Place field at the goal location, suggesting that goal locations can be encoded by local changes in firing rate, within an otherwise stable spatial representation. Therefore, it has been suggested that the coordinated activity of a large fraction of hippocampal Cells at the goal location may interact with the mPFC to compute accurate planning trajectories, relying on both precise location-specific firing of Place Cells and the coarse-coded, goal-trajectory planning function of the prefrontal cortex. To test this hypothesis, we inactivated the mPFC and recorded hippocampal Place Cell activity while animals were performing the navigation task. The results show that post-training inactivation of the prefrontal cortex does not affect behavioral performance, suggesting that this structure is no longer required when animals are overtrained. The goal-related activity of Place Cells was not affected at either single unit or local field potential level. Conversely, profound modifications of Place Cell firing variability (overdispersion) were observed after suppression of prefrontal input, suggesting a possible mechanism underlying behavioral flexibility.
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Local remapping of Place Cell firing in the Tolman detour task.
European Journal of Neuroscience, 2011Co-Authors: Alice Alvernhe, Etienne Save, Bruno PoucetAbstract:The existence of Place Cells, whose discharge is strongly related to a rat’s location in its environment, has led to the proposal that they form part of an integrated neural system dedicated to spatial navigation. It has been suggested that this system could represent space as a cognitive map, which is flexibly used by animals to plan new shortcuts or efficient detours. To further understand the relationships between hippocampal Place Cell firing and cognitive maps, we examined the discharge of Place Cells as rats were exposed to a Tolman-type detour problem. In specific sessions, a transparent barrier was Placed onto the maze so as to block the shortest central path between the two rewarded end locations of a familiar three-way maze. We found that rats rapidly and consistently chose the shortest alternative detour. Furthermore, both CA1 and CA3 Place Cells that had a field in the vicinity of the barrier displayed local remapping. In contrast, neither CA1 nor CA3 Cells that had a field away from the barrier were affected. This finding, at odds with our previous report of altered CA3 discharge for distant fields in a shortcut task, suggests that the availability of a novel path and the blocking of a familiar path are not equivalent and could lead to different responses of the CA3 Place Cell population. Together, the two studies point to a specific role of CA3 in the representation of spatial connectivity and sequences.
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Impaired long term stability of CA1 Place Cell representation in mice lacking the transcription factor zif268/egr1.
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Sophie Renaudineau, Bruno Poucet, Serge Laroche, Sabrina Davis, Etienne SaveAbstract:Zif268 is a transcriptional regulator that plays a crucial role in maintenance of the late phases of hippocampal long-term potentiation (LTP) and consolidation of spatial memories. Because the hippocampal Place Cell system is essential for long-term spatial memory, we tested the hypothesis that zif268 is required for long-term stability of hippocampal Place Cell representations by recording CA1 Place Cells in mice lacking zif268. We found that zif268 gene deletion destabilized the representation of a familiar environment after exposure to a novel environment and impaired the long-term (24 h), but not short-term (1 h), stability of newly formed representations. These impairments could be rescued by repeated exposure to the novel environment, however. These results indicate that zif268 contributes to the long-term stability of spatial representations in CA1 and support the notion that the long-term stability of Place Cell representations requires transcription-dependent mechanisms similar to those observed in LTP.
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impaired long term stability of ca1 Place Cell representation in mice lacking the transcription factor zif268 egr1
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Sophie Renaudineau, Bruno Poucet, Serge Laroche, Sabrina Davis, Etienne SaveAbstract:Zif268 is a transcriptional regulator that plays a crucial role in maintenance of the late phases of hippocampal long-term potentiation (LTP) and consolidation of spatial memories. Because the hippocampal Place Cell system is essential for long-term spatial memory, we tested the hypothesis that zif268 is required for long-term stability of hippocampal Place Cell representations by recording CA1 Place Cells in mice lacking zif268. We found that zif268 gene deletion destabilized the representation of a familiar environment after exposure to a novel environment and impaired the long-term (24 h), but not short-term (1 h), stability of newly formed representations. These impairments could be rescued by repeated exposure to the novel environment, however. These results indicate that zif268 contributes to the long-term stability of spatial representations in CA1 and support the notion that the long-term stability of Place Cell representations requires transcription-dependent mechanisms similar to those observed in LTP.
Rishikesh Narayanan - One of the best experts on this subject based on the ideXlab platform.
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spatially dispersed synapses yield sharply tuned Place Cell responses through dendritic spike initiation
The Journal of Physiology, 2018Co-Authors: Reshma Basak, Rishikesh NarayananAbstract:A prominent hypothesis spanning several sensory-perceptual systems implicates spatially clustered synapses in the generation of dendritic spikes that mediate sharply-tuned neuronal responses to input features. In this conductance-based morphologically-precise computational study, we tested this hypothesis by systematically analysing the impact of distinct synaptic and channel localization profiles on sharpness of spatial tuning in hippocampal pyramidal neurons. We found that the generation of dendritic spikes, the emergence of an excitatory ramp in somatic voltage responses, the expression of several intrinsic somatodendritic functional maps and sharp tuning of Place-Cell responses were all attainable even when iso-feature synapses are randomly dispersed across the dendritic arbor of models with disparate channel combinations. Strikingly, the generation and propagation of dendritic spikes, reliant on dendritic sodium channels and N-methyl-d-asparate receptors, mediated the sharpness of spatial tuning achieved with dispersed synaptic localization. To ensure that our results were not artefacts of narrow parametric choices, we confirmed these conclusions with independent multiparametric stochastic search algorithms spanning thousands of unique models for each synaptic localization scenario.Next, employing virtual knockout models, we demonstrated a vital role for dendritically expressed voltage-gated ion channels, especially the transient potassium channels, in maintaining sharpness of Place-Cell tuning. Importantly, we established that synaptic potentiation targeted to afferents from one specific Place field was sufficient to impart Place field selectivity even when intrinsically disparate neurons received randomly dispersed afferents from multiple Place field locations. Our results provide quantitative evidence for disparate combinations of channel and synaptic localization profiles to concomitantly yield similar tuning and similar intrinsic properties.
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Spatially dispersed synapses yield sharply‐tuned Place Cell responses through dendritic spike initiation
The Journal of Physiology, 2018Co-Authors: Reshma Basak, Rishikesh NarayananAbstract:A prominent hypothesis spanning several sensory-perceptual systems implicates spatially clustered synapses in the generation of dendritic spikes that mediate sharply-tuned neuronal responses to input features. In this conductance-based morphologically-precise computational study, we tested this hypothesis by systematically analysing the impact of distinct synaptic and channel localization profiles on sharpness of spatial tuning in hippocampal pyramidal neurons. We found that the generation of dendritic spikes, the emergence of an excitatory ramp in somatic voltage responses, the expression of several intrinsic somatodendritic functional maps and sharp tuning of Place-Cell responses were all attainable even when iso-feature synapses are randomly dispersed across the dendritic arbor of models with disparate channel combinations. Strikingly, the generation and propagation of dendritic spikes, reliant on dendritic sodium channels and N-methyl-d-asparate receptors, mediated the sharpness of spatial tuning achieved with dispersed synaptic localization. To ensure that our results were not artefacts of narrow parametric choices, we confirmed these conclusions with independent multiparametric stochastic search algorithms spanning thousands of unique models for each synaptic localization scenario.Next, employing virtual knockout models, we demonstrated a vital role for dendritically expressed voltage-gated ion channels, especially the transient potassium channels, in maintaining sharpness of Place-Cell tuning. Importantly, we established that synaptic potentiation targeted to afferents from one specific Place field was sufficient to impart Place field selectivity even when intrinsically disparate neurons received randomly dispersed afferents from multiple Place field locations. Our results provide quantitative evidence for disparate combinations of channel and synaptic localization profiles to concomitantly yield similar tuning and similar intrinsic properties.
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spatially dispersed synapses yield sharply tuned Place Cell responses through dendritic spike initiation
bioRxiv, 2017Co-Authors: Reshma Basak, Rishikesh NarayananAbstract:The literature offers evidence for a critical role of spatially-clustered iso-feature synapses in eliciting dendritic spikes essential for sharp feature selectivity, with apparently contradictory evidence demonstrating spatial dispersion of iso-feature synapses. Here, we reconcile this apparent contradiction by demonstrating that the generation of dendritic spikes, the emergence of an excitatory ramp in somatic voltage responses and sharp tuning of Place-Cell responses are all attainable even when iso-feature synapses are randomly dispersed across the dendritic arbor. We found this tuning sharpness to be critically reliant on dendritic sodium and transient potassium channels and on N-methyl-D-asparate receptors. Importantly, we demonstrate that synaptic potentiation targeted to afferents from one specific Place field is sufficient to effectuate Place-field selectivity even when intrinsically disparate neurons received randomly dispersed afferents from multiple Place-field locations. These conclusions proffer dispersed localization of iso-feature synapses as a strong candidate for achieving sharp feature selectivity in neurons across sensory-perceptual systems.
Gyorgy Buzsaki - One of the best experts on this subject based on the ideXlab platform.
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position theta phase model of hippocampal Place Cell activity applied to quantification of running speed modulation of firing rate
Proceedings of the National Academy of Sciences of the United States of America, 2019Co-Authors: Kathryn Mcclain, David Tingley, David J Heeger, Gyorgy BuzsakiAbstract:Spiking activity of Place Cells in the hippocampus encodes the animal’s position as it moves through an environment. Within a Cell’s Place field, both the firing rate and the phase of spiking in the local theta oscillation contain spatial information. We propose a position–theta-phase (PTP) model that captures the simultaneous expression of the firing-rate code and theta-phase code in Place Cell spiking. This model parametrically characterizes Place fields to compare across Cells, time, and conditions; generates realistic Place Cell simulation data; and conceptualizes a framework for principled hypothesis testing to identify additional features of Place Cell activity. We use the PTP model to assess the effect of running speed in Place Cell data recorded from rats running on linear tracks. For the majority of Place fields, we do not find evidence for speed modulation of the firing rate. For a small subset of Place fields, we find firing rates significantly increase or decrease with speed. We use the PTP model to compare candidate mechanisms of speed modulation in significantly modulated fields and determine that speed acts as a gain control on the magnitude of firing rate. Our model provides a tool that connects rigorous analysis with a computational framework for understanding Place Cell activity.
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Hippocampal Place Cell assemblies are speed-controlled oscillators.
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Caroline Geisler, David Robbe, Michaël B. Zugaro, Anton Sirota, Gyorgy BuzsakiAbstract:The phase of spikes of hippocampal pyramidal Cells relative to the local field theta oscillation shifts forward ("phase precession") over a full theta cycle as the animal crosses the Cell's receptive field ("Place field"). The linear relationship between the phase of the spikes and the travel distance within the Place field is independent of the animal's running speed. This invariance of the phase-distance relationship is likely to be important for coordinated activity of hippocampal Cells and space coding, yet the mechanism responsible for it is not known. Here we show that at faster running speeds Place Cells are active for fewer theta cycles but oscillate at a higher frequency and emit more spikes per cycle. As a result, the phase shift of spikes from cycle to cycle (i.e., temporal precession slope) is faster, yet spatial-phase precession stays unchanged. Interneurons can also show transient-phase precession and contribute to the formation of coherently precessing assemblies. We hypothesize that the speed-correlated acceleration of Place Cell assembly oscillation is responsible for the phase-distance invariance of hippocampal Place Cells.
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Hippocampal Place Cell assemblies are speed-controlled oscillators
Proceedings of the National Academy of Sciences, 2007Co-Authors: Caroline Geisler, David Robbe, Michaël B. Zugaro, Anton Sirota, Gyorgy BuzsakiAbstract:The phase of spikes of hippocampal pyramidal Cells relative to the local field θ oscillation shifts forward (“phase precession”) over a full θ cycle as the animal crosses the Cell's receptive field (“Place field”). The linear relationship between the phase of the spikes and the travel distance within the Place field is independent of the animal's running speed. This invariance of the phase–distance relationship is likely to be important for coordinated activity of hippocampal Cells and space coding, yet the mechanism responsible for it is not known. Here we show that at faster running speeds Place Cells are active for fewer θ cycles but oscillate at a higher frequency and emit more spikes per cycle. As a result, the phase shift of spikes from cycle to cycle (i.e., temporal precession slope) is faster, yet spatial-phase precession stays unchanged. Interneurons can also show transient-phase precession and contribute to the formation of coherently precessing assemblies. We hypothesize that the speed-correlated acceleration of Place Cell assembly oscillation is responsible for the phase–distance invariance of hippocampal Place Cells.
