scholarly journals Combined administration of levetiracetam and valproic acid attenuates age-related hyperactivity of CA3 place cells, reduces place field area, and increases spatial information content in aged rat hippocampus

Hippocampus ◽  
2015 ◽  
Vol 25 (12) ◽  
pp. 1541-1555 ◽  
Author(s):  
Jonathan Robitsek ◽  
Marcia H. Ratner ◽  
Tara Stewart ◽  
Howard Eichenbaum ◽  
David H. Farb
Keyword(s):  
Valproic Acid ◽  
Information Content ◽  
Spatial Information ◽  
Place Cells ◽  
Rat Hippocampus ◽  
Place Field ◽  
Aged Rat ◽  
Age Related ◽  
Combined Administration ◽  
Field Area

scholarly journals Mild Traumatic Brain Injury Decreases Spatial Information Content and Reduces Place Field Stability of Hippocampal CA1 Neurons

2020 ◽  
Vol 37 (2) ◽  
pp. 227-235 ◽  
Author(s):  
John I. Broussard ◽  
John B. Redell ◽  
Jing Zhao ◽  
Mark E. Maynard ◽  
Nobuhide Kobori ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Information Content ◽  
Mild Traumatic Brain Injury ◽  
Spatial Information ◽  
Place Field ◽  
Ca1 Neurons ◽  
Hippocampal Ca1 Neurons ◽  
Hippocampal Ca1

scholarly journals Asymmetry of the temporal code for space by hippocampal place cells

2016 ◽  
Author(s):  
Bryan C. Souza ◽  
Adriano B. L. Tort
Keyword(s):  
Firing Rate ◽  
Spatial Information ◽  
Place Cells ◽  
Spike Timing ◽  
Temporal Coding ◽  
Place Field ◽  
Phase Precession ◽  
Wide Debate ◽  
Rate Coding ◽  
Theta Phase

Hippocampal place cells convey spatial information through spike frequency (“rate coding”) and spike timing relative to the theta phase (“temporal coding”). Whether rate and temporal coding are due to independent or related mechanisms has been the subject of wide debate. Here we show that the spike timing of place cells couples to theta phase before major increases in firing rate, anticipating the animal’s entrance into the classical, rate-based place field. In contrast, spikes rapidly decouple from theta as the animal leaves the place field and firing rate decreases. Therefore, temporal coding has strong asymmetry around the place field center. We further show that the dynamics of temporal coding along space evolves in three stages: phase coupling, phase precession and phase decoupling. These results suggest that place cells represent more future than past locations through their spike timing and that independent mechanisms govern rate and temporal coding.

scholarly journals Choice of method of place cell classification determines the population of cells identified

2021 ◽  
Vol 17 (7) ◽  
pp. e1008835
Author(s):  
Dori M. Grijseels ◽  
Kira Shaw ◽  
Caswell Barry ◽  
Catherine N. Hall
Keyword(s):  
Spatial Information ◽  
Real Data ◽  
Place Cell ◽  
Place Cells ◽  
Optical Methods ◽  
Combination Method ◽  
Cell Detection ◽  
Imaging Data ◽  
Place Field ◽  
Implanted Electrodes

Place cells, spatially responsive hippocampal cells, provide the neural substrate supporting navigation and spatial memory. Historically most studies of these neurons have used electrophysiological recordings from implanted electrodes but optical methods, measuring intracellular calcium, are becoming increasingly common. Several methods have been proposed as a means to identify place cells based on their calcium activity but there is no common standard and it is unclear how reliable different approaches are. Here we tested four methods that have previously been applied to two-photon hippocampal imaging or electrophysiological data, using both model datasets and real imaging data. These methods use different parameters to identify place cells, including the peak activity in the place field, compared to other locations (the Peak method); the stability of cells’ activity over repeated traversals of an environment (Stability method); a combination of these parameters with the size of the place field (Combination method); and the spatial information held by the cells (Information method). The methods performed differently from each other on both model and real data. In real datasets, vastly different numbers of place cells were identified using the four methods, with little overlap between the populations identified as place cells. Therefore, choice of place cell detection method dramatically affects the number and properties of identified cells. Ultimately, we recommend the Peak method be used in future studies to identify place cell populations, as this method is robust to moderate variations in place field within a session, and makes no inherent assumptions about the spatial information in place fields, unless there is an explicit theoretical reason for detecting cells with more narrowly defined properties.

scholarly journals Spatial information transfer in hippocampal place cells depends on trial-to-trial variability, symmetry of place-field firing and biophysical heterogeneities

2020 ◽  
Author(s):  
Ankit Roy ◽  
Rishikesh Narayanan
Keyword(s):  
Information Transfer ◽  
Spatial Information ◽  
Tuning Curve ◽  
Place Cells ◽  
Place Field ◽  
Tuning Curves ◽  
Spatial Tuning ◽  
Model Tuning ◽  
The Impact ◽  
The Relationship

ABSTRACTThe relationship between the feature-tuning curve and information transfer profile of individual neurons provides vital insights about neural encoding. However, the relationship between the spatial tuning curve and spatial information transfer of hippocampal place cells remains unexplored. Here, employing a stochastic search procedure spanning thousands of models, we arrived at 127 conductance-based place-cell models that exhibited signature electrophysiological characteristics and sharp spatial tuning, with parametric values that exhibited neither clustering nor strong pairwise correlations. We introduced trial-to-trial variability in responses and computed model tuning curves and information transfer profiles, using stimulus-specific (SSI) and mutual (MI) information metrics, across locations within the place field. We found spatial information transfer to be heterogeneous across models, but to reduce consistently with increasing degrees of variability. Importantly, whereas reliable low-variability responses implied that maximal information transfer occurred at high-slope regions of the tuning curve, increase in variability resulted in maximal transfer occurring at the peak-firing location in a subset of models. Moreover, experience-dependent asymmetry in place-field firing introduced asymmetries in the information transfer computed through MI, but not SSI, and the impact of activity-dependent variability on information transfer was minimal compared to activity-independent variability. Biophysically, we unveiled a many-to-one relationship between different ion channels and information transfer, and demonstrated critical roles for N-methyl-D-aspartate receptors, transient potassium and dendritic sodium channels in regulating information transfer. Our results emphasize the need to account for trial-to-trial variability, tuning-curve shape and biological heterogeneities while assessing information transfer, and demonstrate ion-channel degeneracy in the regulation of spatial information transfer.

scholarly journals Hippocampal spike-time correlations and place-field overlaps during open field foraging

2019 ◽  
Author(s):  
Mauro M. Monsalve-Mercado ◽  
Yasser Roudi
Keyword(s):  
Open Field ◽  
Spatial Information ◽  
Time Lag ◽  
Place Cells ◽  
Spike Time ◽  
Place Field ◽  
Phase Code ◽  
Place Fields ◽  
Cross Correlations ◽  
The Relationship

AbstractPhase precessing place cells encode spatial information on fine timescales via the timing of their spikes. This phase code has been extensively studied on linear tracks and for short runs in the open field. However, less is known about the phase code on unconstrained trajectories lasting tens of minutes, typical of open field foraging. In previous work (Monsalve-Mercado and Leibold, 2017), an analytic expression was derived for the spike-time cross-correlation between phase precessing place cells during natural foraging in the open field. This expression makes two predictions on how this phase code differs from the linear track case: cross-correlations are symmetric with respect to time, and they represent the distance between pairs of place fields in that the theta-filtered cross-correlations around zero time-lag are positive for cells with nearby fields while they are negative for those with fields further apart. Here we analyze several available open field recordings and show that these predictions hold for pairs of CA1 place cells. We also show that the relationship remains during remapping in CA1, and it is also present in place cells in area CA3. For CA1 place cells of Fmr1-null mice, which exhibit normal place fields but somewhat weaker temporal coordination with respect to theta compared to wild type, the cross-correlations still remain symmetric but the relationship to place field overlap is largely lost. The relationship discussed here describes how spatial information is communicated by place cells to downstream areas in a finer theta-timescale, relevant for learning and memory formation in behavioural tasks lasting tens of minutes in the open field.

scholarly journals Exercise Training Preserves Ischemic Preconditioning in Aged Rat Hearts by Restoring the Myocardial Polyamine Pool

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Weiwei Wang ◽  
Hao Zhang ◽  
Guo Xue ◽  
Li Zhang ◽  
Weihua Zhang ◽  
...  
Keyword(s):  
Exercise Training ◽  
Ischemic Preconditioning ◽  
Ischemia Reperfusion ◽  
Polyamine Metabolism ◽  
Aged Rat ◽  
Isolated Hearts ◽  
Age Related ◽  
Rat Hearts ◽  
Myocardial Ischemia Reperfusion

Background. Ischemic preconditioning (IPC) strongly protects against myocardial ischemia reperfusion (IR) injury. However, IPC protection is ineffective in aged hearts. Exercise training reduces the incidence of age-related cardiovascular disease and upregulates the ornithine decarboxylase (ODC)/polyamine pathway. The aim of this study was to investigate whether exercise can reestablish IPC protection in aged hearts and whether IPC protection is linked to restoration of the cardiac polyamine pool.Methods. Rats aging 3 or 18 months perform treadmill exercises with or without gradient respectively for 6 weeks. Isolated hearts and isolated cardiomyocytes were exposed to an IR and IPC protocol.Results. IPC induced an increase in myocardial polyamines by regulating ODC and spermidine/spermine acetyltransferase (SSAT) in young rat hearts, but IPC did not affect polyamine metabolism in aged hearts. Exercise training inhibited the loss of preconditioning protection and restored the polyamine pool by activating ODC and inhibiting SSAT in aged hearts. An ODC inhibitor,α-difluoromethylornithine, abolished the recovery of preconditioning protection mediated by exercise. Moreover, polyamines improved age-associated mitochondrial dysfunctionin vitro.Conclusion. Exercise appears to restore preconditioning protection in aged rat hearts, possibly due to an increase in intracellular polyamines and an improvement in mitochondrial function in response to a preconditioning stimulus.

scholarly journals Microglial distribution, branching, and clearance activity in aged rat hippocampus are affected by astrocyte meshwork integrity: evidence of a novel cell‐cell interglial interaction

2018 ◽  
Vol 33 (3) ◽  
pp. 4007-4020 ◽  
Author(s):  
Daniele Lana ◽  
Filippo Ugolini ◽  
Gary L. Wenk ◽  
Maria Grazia Giovannini ◽  
Sandra Zecchi-Orlandini ◽  
...  
Keyword(s):  
Rat Hippocampus ◽  
Aged Rat ◽  
Cell Cell
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