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Borzello M, Ramirez S, Treves A, Lee I, Scharfman H, Stark C, Knierim JJ, Rangel LM. Assessments of dentate gyrus function: discoveries and debates. Nat Rev Neurosci 2023; 24:502-517. [PMID: 37316588 PMCID: PMC10529488 DOI: 10.1038/s41583-023-00710-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/28/2023] [Indexed: 06/16/2023]
Abstract
There has been considerable speculation regarding the function of the dentate gyrus (DG) - a subregion of the mammalian hippocampus - in learning and memory. In this Perspective article, we compare leading theories of DG function. We note that these theories all critically rely on the generation of distinct patterns of activity in the region to signal differences between experiences and to reduce interference between memories. However, these theories are divided by the roles they attribute to the DG during learning and recall and by the contributions they ascribe to specific inputs or cell types within the DG. These differences influence the information that the DG is thought to impart to downstream structures. We work towards a holistic view of the role of DG in learning and memory by first developing three critical questions to foster a dialogue between the leading theories. We then evaluate the extent to which previous studies address our questions, highlight remaining areas of conflict, and suggest future experiments to bridge these theories.
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Affiliation(s)
- Mia Borzello
- Department of Cognitive Science, University of California, San Diego, La Jolla, CA, USA
| | - Steve Ramirez
- Department of Psychological and Brain Sciences, Boston University, Boston, MA, USA
| | | | - Inah Lee
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, South Korea
| | - Helen Scharfman
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology and Psychiatry and the Neuroscience Institute, New York University Langone Health, New York, NY, USA
- The Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Craig Stark
- Department of Neurobiology and Behaviour, University of California, Irvine, Irvine, CA, USA
| | - James J Knierim
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
| | - Lara M Rangel
- Department of Cognitive Science, University of California, San Diego, La Jolla, CA, USA.
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2
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Johnson TD, Keefe KR, Rangel LM. Stimulation-induced entrainment of hippocampal network activity: Identifying optimal input frequencies. Hippocampus 2023; 33:85-95. [PMID: 36624658 PMCID: PMC10068596 DOI: 10.1002/hipo.23490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 11/29/2022] [Accepted: 12/04/2022] [Indexed: 01/11/2023]
Abstract
The hippocampus contains rich oscillatory activity, with continuous ebbs and flows of rhythmic currents that constrain its ability to integrate inputs. During associative learning, the hippocampus must integrate inputs from a range of sources carrying information about events and the contexts in which they occur. Under these circumstances, temporal coordination of activity between sender and receiver is likely essential for successful communication. Previously, it has been shown that the coordination of rhythmic activity between the lateral entorhinal cortex (LEC) and the CA1 region of the hippocampus is tightly correlated with the onset of learning in an associative learning task. We aimed to examine whether rhythmic inputs from the LEC in specific frequency ranges were sufficient to enhance the temporal coordination of activity in downstream CA1. In urethane-anesthetized rats, we applied extracellular low-intensity alternating current stimulation across the length of the LEC. Using this method, we aimed to phase-bias ongoing neuronal activity in LEC at a range of different frequencies (from 1.25 to 55 Hz). Rhythmic stimulation of LEC at both 35 and 50 Hz increased the proportion of CA1 neurons significantly entrained to the phase of the applied stimulation current. A subset of stimulation frequencies modified CA1 spiking relationships to the phase of local ongoing CA1 oscillations, with each stimulation frequency exerting a unique influence upon downstream CA1, often in frequency ranges outside the target stimulation frequency. These results suggest there are optimal frequencies for LEC-CA1 communication, and that different profiles of LEC rhythms likely have distinct outcomes upon CA1 processing.
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Affiliation(s)
- Teryn D Johnson
- Department of Cognitive Science, University of California, San Diego, California, USA
| | | | - Lara M Rangel
- Department of Cognitive Science, University of California, San Diego, California, USA
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3
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Johnson TD, Coleman TP, Rangel LM. A flexible likelihood approach for predicting neural spiking activity from oscillatory phase. J Neurosci Methods 2019; 311:307-317. [PMID: 30367887 PMCID: PMC6387742 DOI: 10.1016/j.jneumeth.2018.10.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 10/10/2018] [Accepted: 10/17/2018] [Indexed: 11/18/2022]
Abstract
Background: The synchronous ionic currents that give rise to neural oscillations have complex influences on neuronal spiking activity that are challenging to characterize. New method: Here we present a method to estimate probabilistic relationships between neural spiking activity and the phase of field oscillations using a generalized linear model (GLM) with an overcomplete basis of circular functions. We first use an L1-regularized maximum likelihood procedure to select an active set of regressors from the overcomplete set and perform model fitting using standard maximum likelihood estimation. An information theoretic model selection procedure is then used to identify an optimal subset of regressors and associated coefficients that minimize overfitting. To assess goodness of fit, we apply the time-rescaling theorem and compare model predictions to original data using quantile-quantile plots. Results: Spike-phase relationships in synthetic data were robustly characterized. When applied to in vivo hippocampal data from an awake behaving rat, our method captured a multimodal relationship between the spiking activity of a CA1 interneuron, a theta (5–10 Hz) rhythm, and a nested high gamma (65–135 Hz) rhythm. Comparison with existing methods: Previous methods for characterizing spike-phase relationships are often only suitable for unimodal relationships, impose specific relationship shapes, or have limited ability to assess the accuracy or fit of their characterizations. Conclusions: This method advances the way spike-phase relationships are visualized and quantified, and captures multimodal spike-phase relationships, including relationships with multiple nested rhythms. Overall, our method is a powerful tool for revealing a wide range of neural circuit interactions.
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Affiliation(s)
- Teryn D Johnson
- Department of Cognitive Science, University of California, San Diego, La Jolla, CA 92093, United States.
| | - Todd P Coleman
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, United States.
| | - Lara M Rangel
- Department of Cognitive Science, University of California, San Diego, La Jolla, CA 92093, United States.
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4
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Alexander AS, Rangel LM, Tingley D, Nitz DA. Neurophysiological signatures of temporal coordination between retrosplenial cortex and the hippocampal formation. Behav Neurosci 2018; 132:453-468. [PMID: 30070554 DOI: 10.1037/bne0000254] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Retrosplenial cortex (RSC) is heavily interconnected with a multitude of cortical regions and is directly connected with the hippocampal formation. As such, it is a likely coordinator of information transfer between the hippocampus (HPC) and cortex in the service of spatial cognition and episodic memory. The current work examined three potential temporal frameworks for retrosplenial-hippocampal communication, namely, theta frequency oscillations (6-12 Hz), sharp-wave/ripple events, and repeating, theta phase-locked shifts from low (30-65 Hz) to high (120-160 Hz) gamma frequency oscillations. From simultaneous recordings of single units and local field potentials (LFPs) in RSC and HPC, we report the presence of prominent theta, low-gamma, and high-gamma oscillations in the retrosplenial LFP. Retrosplenial and hippocampal theta rhythms were strongly coherent and subgroups of retrosplenial neurons exhibited either spiking at theta frequencies and/or spike-phase-locking to theta. Retrosplenial neurons were also phase-locked to local low- and high-gamma rhythms, and power in these frequency bands was coupled in a sequential fashion to specific phases of hippocampal and retrosplenial theta rhythms. Coordinated activity between the two regions also occurred during hippocampal sharp-wave/ripple events, where retrosplenial neuron populations were modulated in their spiking and retrosplenial LFPs exhibited sharp-wave-like events that co-occurred with those observed in HPC. These results identify several temporal windows of synchronization between RSC and HPC that may mediate cortico-hippocampal processes related to learning, memory, and spatial representation. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
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Zhuo JM, Tseng HA, Desai M, Bucklin ME, Mohammed AI, Robinson NT, Boyden ES, Rangel LM, Jasanoff AP, Gritton HJ, Han X. Young adult born neurons enhance hippocampal dependent performance via influences on bilateral networks. eLife 2016; 5. [PMID: 27914197 PMCID: PMC5156524 DOI: 10.7554/elife.22429] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 11/16/2016] [Indexed: 02/06/2023] Open
Abstract
Adult neurogenesis supports performance in many hippocampal dependent tasks. Considering the small number of adult-born neurons generated at any given time, it is surprising that this sparse population of cells can substantially influence behavior. Recent studies have demonstrated that heightened excitability and plasticity may be critical for the contribution of young adult-born cells for certain tasks. What is not well understood is how these unique biophysical and synaptic properties may translate to networks that support behavioral function. Here we employed a location discrimination task in mice while using optogenetics to transiently silence adult-born neurons at different ages. We discovered that adult-born neurons promote location discrimination during early stages of development but only if they undergo maturation during task acquisition. Silencing of young adult-born neurons also produced changes extending to the contralateral hippocampus, detectable by both electrophysiology and fMRI measurements, suggesting young neurons may modulate location discrimination through influences on bilateral hippocampal networks. DOI:http://dx.doi.org/10.7554/eLife.22429.001
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Affiliation(s)
- Jia-Min Zhuo
- Biomedical Engineering Department, Boston University, Boston, United States
| | - Hua-An Tseng
- Biomedical Engineering Department, Boston University, Boston, United States
| | - Mitul Desai
- Department of Bioengineering, McGovern Institute, Cambridge, United States
| | - Mark E Bucklin
- Biomedical Engineering Department, Boston University, Boston, United States
| | - Ali I Mohammed
- Biomedical Engineering Department, Boston University, Boston, United States
| | - Nick Tm Robinson
- Department of Psychology, Boston University, Boston, United States
| | - Edward S Boyden
- Department of Bioengineering, McGovern Institute, Cambridge, United States.,Media Lab, Massachusetts Institute of Technology, Cambridge, United States
| | - Lara M Rangel
- Department of Psychology, Boston University, Boston, United States
| | - Alan P Jasanoff
- Department of Bioengineering, McGovern Institute, Cambridge, United States
| | - Howard J Gritton
- Biomedical Engineering Department, Boston University, Boston, United States
| | - Xue Han
- Biomedical Engineering Department, Boston University, Boston, United States
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6
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Rangel LM, Alexander AS, Aimone JB, Wiles J, Gage FH, Chiba AA, Quinn LK. Temporally selective contextual encoding in the dentate gyrus of the hippocampus. Nat Commun 2016; 5:3181. [PMID: 24518986 PMCID: PMC3929785 DOI: 10.1038/ncomms4181] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 12/24/2013] [Indexed: 12/24/2022] Open
Abstract
A recent model of the hippocampus predicts that the unique properties of the dentate gyrus allow for temporal separation of events. This temporal separation is accomplished in part through the continual generation of new neurons, which, due to a transient window of hyperexcitability, could allow for preferential encoding of information present during their development. Here we obtain in vivo electrophysiological recordings and identify a cell population exhibiting activity that is selective to single contexts when rats experience a long temporal separation between context exposures during training. This selectivity is attenuated as the temporal separation between context exposures is shortened and is further attenuated when neurogenesis is reduced. Our data reveal the existence of a temporal orthogonalizing neuronal code within the dentate gyrus, a hallmark feature of episodic memory.
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Affiliation(s)
- L M Rangel
- 1] Program in Neurosciences, University of California, San Diego, California, USA [2] Salk Institute for Biological Sciences, La Jolla, California 92037, USA [3]
| | - A S Alexander
- Department of Cognitive Science, University of California, San Diego, California 92093, USA
| | - J B Aimone
- 1] Salk Institute for Biological Sciences, La Jolla, California 92037, USA [2]
| | - J Wiles
- School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, Queensland 4072, Australia
| | - F H Gage
- 1] Program in Neurosciences, University of California, San Diego, California, USA [2] Salk Institute for Biological Sciences, La Jolla, California 92037, USA
| | - A A Chiba
- 1] Program in Neurosciences, University of California, San Diego, California, USA [2] Department of Cognitive Science, University of California, San Diego, California 92093, USA
| | - L K Quinn
- Department of Cognitive Science, University of California, San Diego, California 92093, USA
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7
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Rangel LM, Rueckemann JW, Riviere PD, Keefe KR, Porter BS, Heimbuch IS, Budlong CH, Eichenbaum H. Rhythmic coordination of hippocampal neurons during associative memory processing. eLife 2016; 5:e09849. [PMID: 26751780 PMCID: PMC4718808 DOI: 10.7554/elife.09849] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 11/02/2015] [Indexed: 11/13/2022] Open
Abstract
Hippocampal oscillations are dynamic, with unique oscillatory frequencies present during different behavioral states. To examine the extent to which these oscillations reflect neuron engagement in distinct local circuit processes that are important for memory, we recorded single cell and local field potential activity from the CA1 region of the hippocampus as rats performed a context-guided odor-reward association task. We found that theta (4–12 Hz), beta (15–35 Hz), low gamma (35–55 Hz), and high gamma (65–90 Hz) frequencies exhibited dynamic amplitude profiles as rats sampled odor cues. Interneurons and principal cells exhibited unique engagement in each of the four rhythmic circuits in a manner that related to successful performance of the task. Moreover, principal cells coherent to each rhythm differentially represented task dimensions. These results demonstrate that distinct processing states arise from the engagement of rhythmically identifiable circuits, which have unique roles in organizing task-relevant processing in the hippocampus. DOI:http://dx.doi.org/10.7554/eLife.09849.001 Electrodes placed on the surface of the scalp can reveal rhythmic patterns of electrical activity within the brain. These rhythms reflect the coordinated firing of large numbers of neurons that are connected together within a network in order to process information. A single network can show rhythms with various different frequencies depending on its local connections and the pattern of input that it receives at any given time. One region that exhibits striking changes in these rhythmic patterns is the hippocampus: a brain area that plays a key role in memory. The hippocampus contains many cell types, including interneurons (which form connections with nearby cells) and principal cells (which connect with cells outside of this region). Though both participate in rhythmic circuits, little is known about the different extents to which these distinct cell types are engaged in rhythmic processing, or how rhythmic processing might support memory. Rangel, Rueckemann, Rivière et al. have now addressed these questions by using electrodes to record from the hippocampus as rats learned to associate specific odors in different environments with a reward. As the rats sniffed the odors, their brains showed four different hippocampal rhythms: from a low frequency called “theta”, through “beta” and “low gamma” up to “high gamma” frequencies. Each of these hippocampal rhythms varied in strength over time, indicating that rhythmic processing is dynamic during the task. Rangel, Rueckemann, Rivière et al. found that neurons fired rhythmically during trials in which the rat chose the correct odor-environment combination. In these correct trials, individual principal cells were more likely to fire in synchrony with only one of the rhythms. In contrast, interneurons were more likely to fire in synchrony to each of the four rhythms at some point during a correct choice. Among the four rhythms, coordinated principal cell and interneuron firing with respect to the beta rhythm was most tightly linked with a correct choice. These findings reveal that investigation of rhythmic dynamics in the hippocampus can provide insight into how the timing of cell activity is coordinated to support memory. DOI:http://dx.doi.org/10.7554/eLife.09849.002
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Affiliation(s)
- Lara M Rangel
- Center for Memory and Brain, Boston University, Boston, United States.,Cognitive Rhythms Collaborative, Boston University, Boston, United States.,Bioengineering Department, University of California, San Diego, La Jolla, United States
| | - Jon W Rueckemann
- Center for Memory and Brain, Boston University, Boston, United States
| | - Pamela D Riviere
- Center for Memory and Brain, Boston University, Boston, United States
| | - Katherine R Keefe
- Center for Memory and Brain, Boston University, Boston, United States
| | - Blake S Porter
- Center for Memory and Brain, Boston University, Boston, United States.,University of Otago, Dunedin, New Zealand
| | - Ian S Heimbuch
- Center for Memory and Brain, Boston University, Boston, United States.,University of California, Los Angeles, Los Angeles, United States
| | - Carl H Budlong
- Center for Memory and Brain, Boston University, Boston, United States
| | - Howard Eichenbaum
- Center for Memory and Brain, Boston University, Boston, United States
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Rueckemann JW, DiMauro AJ, Rangel LM, Han X, Boyden ES, Eichenbaum H. Transient optogenetic inactivation of the medial entorhinal cortex biases the active population of hippocampal neurons. Hippocampus 2015; 26:246-60. [PMID: 26299904 DOI: 10.1002/hipo.22519] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 08/20/2015] [Indexed: 11/07/2022]
Abstract
The mechanisms that enable the hippocampal network to express the appropriate spatial representation for a particular circumstance are not well understood. Previous studies suggest that the medial entorhinal cortex (MEC) may have a role in reproducibly selecting the hippocampal representation of an environment. To examine how ongoing MEC activity is continually integrated by the hippocampus, we performed transient unilateral optogenetic inactivations of the MEC while simultaneously recording place cell activity in CA1. Inactivation of the MEC caused a partial remapping in the CA1 population without diminishing the degree of spatial tuning across the active cell assembly. These changes remained stable irrespective of intermittent disruption of MEC input, indicating that while MEC input is integrated over long time scales to bias the active population, there are mechanisms for stabilizing the population of active neurons independent of the MEC. We find that MEC inputs to the hippocampus shape its ongoing activity by biasing the participation of the neurons in the active network, thereby influencing how the hippocampus selectively represents information.
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Affiliation(s)
- Jon W Rueckemann
- Center for Memory and Brain, Boston University, Boston, Massachusetts
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, USA
| | - Audrey J DiMauro
- Center for Memory and Brain, Boston University, Boston, Massachusetts
- Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA
| | - Lara M Rangel
- Center for Memory and Brain, Boston University, Boston, Massachusetts
| | - Xue Han
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | - Edward S Boyden
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Howard Eichenbaum
- Center for Memory and Brain, Boston University, Boston, Massachusetts
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Rangel LM, Chiba AA, Quinn LK. Theta and beta oscillatory dynamics in the dentate gyrus reveal a shift in network processing state during cue encounters. Front Syst Neurosci 2015; 9:96. [PMID: 26190979 PMCID: PMC4486843 DOI: 10.3389/fnsys.2015.00096] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/12/2015] [Indexed: 12/22/2022] Open
Abstract
The hippocampus is an important structure for learning and memory processes, and has strong rhythmic activity. Although a large amount of research has been dedicated toward understanding the rhythmic activity in the hippocampus during exploratory behaviors, specifically in the theta (5–10 Hz) frequency range, few studies have examined the temporal interplay of theta and other frequencies during the presentation of meaningful cues. We obtained in vivo electrophysiological recordings of local field potentials (LFP) in the dentate gyrus (DG) of the hippocampus as rats performed three different associative learning tasks. In each task, cue presentations elicited pronounced decrements in theta amplitude in conjunction with increases in beta (15–30 Hz) amplitude. These changes were often transient but were sustained from the onset of cue encounters until the occurrence of a reward outcome. This oscillatory profile shifted in time to precede cue encounters over the course of the session, and was not present during similar behaviors in the absence of task relevant stimuli. The observed decreases in theta amplitude and increases in beta amplitude in the DG may thus reflect a shift in processing state that occurs when encountering meaningful cues.
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Affiliation(s)
- Lara M Rangel
- Cognitive Rhythms Collaborative, Laboratory of Cognitive Neurobiology, CAS Psychology, Boston University Boston, MA, USA
| | - Andrea A Chiba
- Department of Cognitive Science, University of California San Diego La Jolla, CA, USA
| | - Laleh K Quinn
- Department of Cognitive Science, University of California San Diego La Jolla, CA, USA
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10
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Abstract
A recent study suggests that coherence of 20-40 Hz brain oscillations in the hippocampus and upstream lateral entorhinal cortex may support encoding of task-relevant information during associative learning. Coordination of local hippocampal circuits in this frequency range could be important for encoding new information.
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Affiliation(s)
- L M Rangel
- Center for Memory and Brain, Boston University, 2 Cummington Street, Boston University, Boston, MA 02215, USA
| | - H Eichenbaum
- Center for Memory and Brain, Boston University, 2 Cummington Street, Boston University, Boston, MA 02215, USA.
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Rangel LM, Quinn LK, Chiba AA, Gage FH, Aimone JB. A hypothesis for temporal coding of young and mature granule cells. Front Neurosci 2013; 7:75. [PMID: 23717259 PMCID: PMC3653099 DOI: 10.3389/fnins.2013.00075] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 04/26/2013] [Indexed: 01/22/2023] Open
Abstract
While it has been hypothesized that adult neurogenesis (NG) plays a role in the encoding of temporal information at long time-scales, the temporal relationship of immature cells to the highly rhythmic network activity of the hippocampus has been largely unexplored. Here, we present a theory for how the activity of immature adult-born granule cells relates to hippocampal oscillations. Our hypothesis is that theta rhythmic (5–10 Hz) excitatory and inhibitory inputs into the hippocampus could differentially affect young and mature granule cells due to differences in intrinsic physiology and synaptic inhibition between the two cell populations. Consequently, immature cell activity may occur at broader ranges of theta phase than the activity of their mature counterparts. We describe how this differential influence on young and mature granule cells could separate the activity of differently aged neurons in a temporal coding regime. Notably, this process could have considerable implications on how the downstream CA3 region interprets the information conveyed by young and mature granule cells. To begin to investigate the phasic behavior of granule cells, we analyzed in vivo recordings of the rat dentate gyrus (DG), observing that the temporal behavior of granule cells with respect to the theta rhythm is different between rats with normal and impaired levels of NG. Specifically, in control animals, granule cells exhibit both strong and weak coupling to the phase of the theta rhythm. In contrast, the distribution of phase relationships in NG-impaired rats is shifted such that they are significantly stronger. These preliminary data support our hypothesis that immature neurons could distinctly affect the temporal dynamics of hippocampal encoding.
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Affiliation(s)
- Lara M Rangel
- Department of Neurosciences, University of California San Diego, CA, USA ; Department of Mathematics and Statistics, Boston University Boston, MA, USA
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12
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Abstract
Distinct populations of active cells in the dentate gyrus of the hippocampus may facilitate the unique encoding of changes in the environment.
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Affiliation(s)
- Lara M Rangel
- is at the Center for Memory and Brain , Boston University , Boston , United States
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13
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Labardini-Méndez JR, Gariglio P, Rangel LM, García E, Calvo J, Velázquez-González A, Cruz A, Cerezo RM, Ortega V, Sobrevilla-Calvo PJ. [Acute myeloblastic leukemia]. GAC MED MEX 2001; 137:31-51. [PMID: 11244826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Affiliation(s)
- J R Labardini-Méndez
- Dirección de Docencia, Instituto Nacional De Cancerología, Cerro Tres Marías 271 C.P. 04200 Coyoacán, D.F
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14
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Mendoza L, Rangel LM, Garcia E, Sanchez T, Gariglio P, Orozco E. Detection of a human p53-like protein in E. histolytica. Arch Med Res 1997; 28 Spec No:17-8. [PMID: 9032996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- L Mendoza
- Departamento de Patología Experimental, Centro de Investigación y de Estudios Avanzados del IPN, México, D.F., Mexico
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15
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Abstract
The evolutionarily conserved proto-oncogene c-myc is involved in both proliferation and differentiation processes of higher eukaryotic cells. We report here the identification and characterization of sequences homologous to c-myc in different Entamoeba species using a fragment of the mammalian c-myc gene as a probe. This probe hybridized with fragments of 3.5 and 3.4 kilobases (kb) in E. histolytica HindIII of EcoRI digested DNA. In E. invadens it recognized fragments of 3.1 and 2.8 kb, and in Laredo strain (reported as E. moshkovskii by Clark and Diamond in 1991) the probe hybridized with fragments of 17 kb. The c-myc probe identified transcripts of 3.3 and 1.5 kb in E. histolytica, transcripts of 1.8 and 1.3 kb in Laredo strain, and transcripts of 3.7, 1.8, 1.5 and 1.1 kb in E. invadens. Antibodies against a highly conserved region of the c-myc protein recognized in E. histolytica polypeptides of 35, 40, and 60 kDa. The expression of the 60 kDa polypeptide was temperature-inducible in Laredo strain. In E. invadens a 110 kDa strong band was detected by the antibodies. Surprisingly, E. invadens myc-like sequences and proteins showed greater homology to mammalian c-myc gene and proteins. Expression of proteins antigenically related to c-myc varied according to the cell cycle phase of E. histolytica. These proteins peaked during D, G1, and S phases and declined during G2.
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Affiliation(s)
- M Leyva Leyva
- Department of Experimental Pathology, CINVESTAV-IPN, México, D.F
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16
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Gariglio P, Rangel LM. [Virus and cancer]. Salud Publica Mex 1992; 34:308-17. [PMID: 1319613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
There are at least four viruses tightly associated with human cancer: HTLY-I and HTLY-II with certain leukemias, EBV with lymphomas, BHV with hepatocarcinomas and HPV with genital cancer. In this work we discuss some evidences indicating these associations; in particular we emphasize the characteristics of human papillomavirus (HPV), due to its growing importance in the development of uterine-cervix carcinoma and the mortality of Mexican women. The low percentage of infected individuals that develop these neoplasias and the long latency periods observed indicate that both cellular and environmental factors are involved in tumor induction. Among cellular factors, oncogenes (such as myc) and antioncogenes could play important roles in the induction and development of the malignant phenotype. The understanding of these factors could lead to the development of methods for early diagnosis and therapy of cancer.
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Affiliation(s)
- P Gariglio
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México
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Talmage DA, Freund R, Dubensky T, Salcedo M, Gariglio P, Rangel LM, Dawe CJ, Benjamin TL. Heterogeneity in state and expression of viral DNA in polyoma virus-induced tumors of the mouse. Virology 1992; 187:734-47. [PMID: 1312275 DOI: 10.1016/0042-6822(92)90476-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We have examined the state and expression of polyoma viral DNA in representative epithelial and mesenchymal tumors, using a combination of biochemical and in situ methods. Results showed wide variations among tumor types and also in different regions within individual tumors, with respect to copy number of viral DNA, presence or absence of deletions, and expression of early and late viral proteins. Epithelial tumors showed the greatest heterogeneity. High copy free viral DNA, frequently with deletions, was found in all such tumors. A portion of free viral DNA was recoverable as transcriptionally active minichromosomes. Three distinct subpopulations of cells were distinguished by in situ analyses. Type 1 cells showed high copy free viral DNA and expressed the major viral capsid protein VP1; these cells appeared to be at various stages of productive (lytic) viral infection. Some productively infected cells were able to undergo mitosis; in a portion of these cells, VP1 was found in close association with the mitotic spindle. Type 2 cells contained high copy free DNA but did not express VP1; by some unknown mechanism, these cells manifest a post-replication block to late gene expression and lytic infection. Type 3 cells contained only low copy, presumably integrated, viral DNA and expressed no VP1; they thus resemble cells transformed in vitro by the virus. Epithelial tumors contained variable mixtures of these subpopulations, while mesenchymal tumors were composed of Type 3 cells only. Differences in virus-cell interactions are discussed in terms of their possible implications in tumor development.
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Affiliation(s)
- D A Talmage
- Institute of Human Nutrition, Columbia University, New York, New York 10032
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18
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Rangel LM, Fernández-Tomas C, Dahmus ME, Gariglio P. Poliovirus-induced modification of host cell RNA polymerase IIO is prevented by cycloheximide and zinc. J Biol Chem 1988; 263:19267-9. [PMID: 2848819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Infection of HeLa cells with poliovirus results in a decrease in the level of RNA polymerase IIO, the transcriptionally active form of the enzyme, and a shutdown of host transcription (Rangel, L. M., Fernández-Tomas, C., Dahmus, M. E., and Gariglio, P. (1987) J. Virol. 61, 1002-1006). The effect of cycloheximide on poliovirus-induced modification of host RNA polymerase IIO was investigated. The inhibition of protein synthesis, at sequential stages during viral replication, prevents the modification of both total and chromatin-bound RNA polymerase IIO. Furthermore, the inclusion of zinc at a concentration that inhibits the proteolytic post-translational processing of viral polyprotein also prevents the modification of RNA polymerase IIO. These results suggest that host cell enzyme modification depends on the synthesis and processing of protein(s) encoded by the viral genome.
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Affiliation(s)
- L M Rangel
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados-IPN, México
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Baeza I, Gariglio P, Rangel LM, Chavez P, Cervantes L, Arguello C, Wong C, Montañez C. Electron microscopy and biochemical properties of polyamine-compacted DNA. Biochemistry 1987; 26:6387-92. [PMID: 3322379 DOI: 10.1021/bi00394a012] [Citation(s) in RCA: 105] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We have obtained polyamine-compacted DNA and analyzed it by electron microscopy employing the method described by Dubochet, suitable for the study of complexes in which the main interactions are of ionic character. In addition, we have developed a simple biochemical method, based on the action of pancreatic DNase I, to demonstrate the condensation of DNA with spermidine. DNA-spermidine complexes are resistant to the action of DNase I, and there is a strong correlation between the presence of condensed DNA forms, both as toroids and as cylinders, and the insensitivity to DNase I activity. We have also shown that pBR322 DNA-spermidine complexes are transcriptionally active in the presence of Escherichia coli RNA polymerase. This supports the data concerning the biological activity of spermidine-condensed DNA.
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Affiliation(s)
- I Baeza
- Department of Biochemistry, Escuela Nacional de Ciencias Biologicas del IPN, Mexico, DF
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Abstract
Infection of HeLa cells with poliovirus results in a shutdown of host transcription. In an effort to understand the mechanism(s) that underlies this process, we analyzed the distribution of RNA polymerase IIO before and after viral infection. Analysis of free and chromatin-bound enzyme indicated that there is a significant reduction in RNA polymerase IIO following infection. This observation, together with increasing evidence that transcription is catalyzed by RNA polymerase IIO, supports the hypothesis that poliovirus-induced inhibition of host transcription occurs at the level of RNA chain initiation and involves the direct modification of RNA polymerase II.
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