scholarly journals State transitions in the statistically stable place cell population are determined by visual change

2021 ◽  
Author(s):  
Sander Tanni ◽  
William de Cothi ◽  
Caswell Barry
Keyword(s):  
Cell Population ◽  
Population Level ◽  
Place Cell ◽  
State Transitions ◽  
Variable Rate ◽  
Visual Change ◽  
Large Numbers ◽  
Level Statistics ◽  
Place Fields ◽  
Field Area

The hippocampus plays a central role in mammalian navigation and memory, yet an implementational understanding of the rules that govern the formation of individual place fields and the spatial-statistics of the population as a whole are lacking. We analysed large numbers of CA1 place fields recorded while rats foraged in different-sized environments up to 8.75 m2. We found that place cell propensities to form fields were proportional to open-field area, gamma-distributed, and conserved across environments. The properties of place fields varied positionally with a denser distribution of smaller fields near boundaries. Remarkably, the variation in field sizes and densities exactly countered each other, such that the population-level statistics were constant both within and between environments. Using a virtual reality replica of the environment, we showed that this variable rate of transition through the statistically stable place cell population was matched to change in the animals' visual scenes.

Hippocampal Place-Cell Firing During Movement in Three-Dimensional Space

2001 ◽  
Vol 85 (1) ◽  
pp. 105-116 ◽  
Author(s):  
James J. Knierim ◽  
Bruce L. McNaughton
Keyword(s):  
Hippocampal Neurons ◽  
Horizontal Plane ◽  
Three Dimensional ◽  
Place Cell ◽  
Place Cells ◽  
Limbic Cortex ◽  
Head Direction ◽  
Head Direction Cells ◽  
Recording Apparatus ◽  
Place Fields

“Place” cells of the rat hippocampus are coupled to “head direction” cells of the thalamus and limbic cortex. Head direction cells are sensitive to head direction in the horizontal plane only, which leads to the question of whether place cells similarly encode locations in the horizontal plane only, ignoring the z axis, or whether they encode locations in three dimensions. This question was addressed by recording from ensembles of CA1 pyramidal cells while rats traversed a rectangular track that could be tilted and rotated to different three-dimensional orientations. Cells were analyzed to determine whether their firing was bound to the external, three-dimensional cues of the environment, to the two-dimensional rectangular surface, or to some combination of these cues. Tilting the track 45° generally provoked a partial remapping of the rectangular surface in that some cells maintained their place fields, whereas other cells either gained new place fields, lost existing fields, or changed their firing locations arbitrarily. When the tilted track was rotated relative to the distal landmarks, most place fields remapped, but a number of cells maintained the same place field relative to the x-y coordinate frame of the laboratory, ignoring the z axis. No more cells were bound to the local reference frame of the recording apparatus than would be predicted by chance. The partial remapping demonstrated that the place cell system was sensitive to the three-dimensional manipulations of the recording apparatus. Nonetheless the results were not consistent with an explicit three-dimensional tuning of individual hippocampal neurons nor were they consistent with a model in which different sets of cells are tightly coupled to different sets of environmental cues. The results are most consistent with the statement that hippocampal neurons can change their “tuning functions” in arbitrary ways when features of the sensory input or behavioral context are altered. Understanding the rules that govern the remapping phenomenon holds promise for deciphering the neural circuitry underlying hippocampal function.

scholarly journals Electroencephalographic Evidence for Individual Neural Inertia in Mice That Decreases With Time

2022 ◽  
Vol 15 ◽  
Author(s):  
Andrzej Z. Wasilczuk ◽  
Qing Cheng Meng ◽  
Andrew R. McKinstry-Wu
Keyword(s):  
Stochastic Model ◽  
Path Dependence ◽  
Inbred Mice ◽  
Population Level ◽  
Supervised Machine Learning ◽  
State Transitions ◽  
Intrinsic Resistance ◽  
Linear Discriminant ◽  
Individual Level ◽  
Increased Risk

Previous studies have demonstrated that the brain has an intrinsic resistance to changes in arousal state. This resistance is most easily measured at the population level in the setting of general anesthesia and has been termed neural inertia. To date, no study has attempted to determine neural inertia in individuals. We hypothesize that individuals with markedly increased or decreased neural inertia might be at increased risk for complications related to state transitions, from awareness under anesthesia, to delayed emergence or confusion/impairment after emergence. Hence, an improved theoretical and practical understanding of neural inertia may have the potential to identify individuals at increased risk for these complications. This study was designed to explicitly measure neural inertia in individuals and empirically test the stochastic model of neural inertia using spectral analysis of the murine EEG. EEG was measured after induction of and emergence from isoflurane administered near the EC50 dose for loss of righting in genetically inbred mice on a timescale that minimizes pharmacokinetic confounds. Neural inertia was assessed by employing classifiers constructed using linear discriminant or supervised machine learning methods to determine if features of EEG spectra reliably demonstrate path dependence at steady-state anesthesia. We also report the existence of neural inertia at the individual level, as well as the population level, and that neural inertia decreases over time, providing direct empirical evidence supporting the predictions of the stochastic model of neural inertia.

scholarly journals Position-theta-phase model of hippocampal place cell activity applied to quantification of running speed modulation of firing rate

2019 ◽  
Author(s):  
Kathryn McClain ◽  
David Tingley ◽  
David Heeger ◽  
György Buzsáki
Keyword(s):  
Firing Rate ◽  
Spatial Information ◽  
Cell Activity ◽  
Gain Control ◽  
Place Cell ◽  
Small Subset ◽  
Running Speed ◽  
Speed Modulation ◽  
Place Fields ◽  
Theta Phase

AbstractSpiking 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 condition, 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.SignificanceThe hippocampus is heavily studied in the context of spatial navigation, and the format of spatial information in hippocampus is multifaceted and complex. Furthermore, the hippocampus is also thought to contain information about other important aspects of behavior such as running speed, though there is not agreement on the nature and magnitude of their effect. To understand how all of these variables are simultaneously represented and used to guide behavior, a theoretical framework is needed that can be directly applied to the data we record. We present a model that captures well-established spatial-encoding features of hippocampal activity and provides the opportunity to identify and incorporate novel features for our collective understanding.

scholarly journals A Stochastic Model for Virus Growth in a Cell Population

2014 ◽  
Vol 51 (3) ◽  
pp. 599-612 ◽  
Author(s):  
J. E. Björnberg ◽  
T. Britton ◽  
E. I. Broman ◽  
E. Natan
Keyword(s):  
Stochastic Model ◽  
Host Cell ◽  
Cell Population ◽  
Branching Process ◽  
Virus Population ◽  
Virus Growth ◽  
Optimal Balance ◽  
Large Numbers ◽  
A Cell

In this work we introduce a stochastic model for the spread of a virus in a cell population where the virus has two ways of spreading: either by allowing its host cell to live and duplicate, or by multiplying in large numbers within the host cell, causing the host cell to burst and thereby let the virus enter new uninfected cells. The model is a kind of interacting Markov branching process. We focus in particular on the probability that the virus population survives and how this depends on a certain parameter λ which quantifies the ‘aggressiveness’ of the virus. Our main goal is to determine the optimal balance between aggressive growth and long-term success. Our analysis shows that the optimal strategy of the virus (in terms of survival) is obtained when the virus has no effect on the host cell's life cycle, corresponding to λ = 0. This is in agreement with experimental data about real viruses.

Albatrosses bathe before departing on a foraging trip: implications for risk assessments and marine spatial planning

2017 ◽  
Vol 28 (2) ◽  
pp. 208-215 ◽  
Author(s):  
JOSÉ P. GRANADEIRO ◽  
LETIZIA CAMPIONI ◽  
PAULO CATRY
Keyword(s):  
Spatial Planning ◽  
Population Level ◽  
Sea Surface ◽  
Risk Assessments ◽  
Marine Spatial Planning ◽  
Large Numbers ◽  
Highly Sensitive ◽  
Order Of Magnitude ◽  
Thalassarche Melanophris ◽  
Marine Areas

SummaryTracking studies of seabirds have generally focused in identifying areas used for foraging, in the hope of highlighting regions of energy transfer which may be important for seabird and general ecosystem conservation and special management. However, some sea areas may serve functions other than providing nutritional resources, which may be equally relevant, particularly if used by large numbers of individuals. In this paper, based on a study of 4 breeding colonies in the Falkland Islands and on 314 individuals tracked, we show that virtually all (97.8%) black-browed albatrosses Thalassarche melanophris (BBA) bathe in the close vicinity of the colony, remaining in the area for nearly an hour, before departing on a foraging trip. This compares with only 20 to 40% of the individuals landing close to the colony at the end of a foraging trip. The observed utilization of marine areas by BBA in a radius of 1 to 5 km around the nesting colony is one order of magnitude higher than elsewhere, including foraging hotspots. Clearly, even long-range flying birds such as albatrosses can make an intensive use of the sea-surface in the immediate vicinity of the colonies, and therefore any threats to seabirds in these areas (disturbance, pollutants, collision with artificial structures and light attraction) can potentially have a major impact at the population level. As such, the close neighbourhood of seabird colonies are potentially highly sensitive areas, and this needs to be taken into account when carrying out risk assessments or during marine spatial planning exercises.

The immediate induction of extensive cell fusion by Ca2+ addition in Dictyostelium discoideum

1986 ◽  
Vol 64 (12) ◽  
pp. 1281-1287 ◽  
Author(s):  
David R. McConachie ◽  
Danton H. O'Day
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Fusion ◽  
Cell Population ◽  
Giant Cells ◽  
Binucleate Cells ◽  
Large Numbers ◽  
Synchronous Cell ◽  
Extensive Cell ◽  
Chloride Salts

In mated cultures (NC4 × V12) of Dictyostelium discoideum containing 1.0 mM CaCl2, cell fusion generates large numbers of binucleate cells which develop into zygote giant cells. In the absence of Ca2+, binucleate formation does not occur. When 1.0 mM CaCl2 is added to Ca2+-deficient cultures at 18 h, 50% of the cells fuse within 45 min producing large multinucleate syncytia. Small, presumptive gametes appear in Ca2+-deficient cultures and reach a peak of about 20% of the cell population by 10 h, but they maintain this plateau and do not fuse. Upon the addition of CaCl2, the presumptive gametes immediately fuse, producing binucleate cells which develop rapidly into morphologically distinct giant cells. Cell fusion continues, resulting in the formation of extremely large (40–80 μm diameter) multinucleate syncytia by 45 min. The induction of this extensive, synchronous cell fusion does not occur in the presence of other chloride salts and EGTA inhibits it, revealing that Ca+ is the regulatory ion.

scholarly journals Analysis of stochastic fluctuations in responsiveness is a critical step toward personalized anesthesia

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Andrew R McKinstry-Wu ◽  
Andrzej Z Wasilczuk ◽  
Benjamin A Harrison ◽  
Victoria M Bedell ◽  
Mathangi J Sridharan ◽  
...  
Keyword(s):  
Drug Sensitivity ◽  
Population Level ◽  
Population Based ◽  
State Transitions ◽  
Response Relationship ◽  
Drug Dosing ◽  
Stochastic Fluctuations ◽  
Fixed Drug ◽  
Biological Substrate ◽  
The Relationship

Traditionally, drug dosing is based on a concentration-response relationship estimated in a population. Yet, in specific individuals, decisions based on the population-level effects frequently result in over or under-dosing. Here, we interrogate the relationship between population-based and individual-based responses to anesthetics in mice and zebrafish. The anesthetic state was assessed by quantifying responses to simple stimuli. Individual responses dynamically fluctuated at a fixed drug concentration. These fluctuations exhibited resistance to state transitions. Drug sensitivity varied dramatically across individuals in both species. The amount of noise driving transitions between states, in contrast, was highly conserved in vertebrates separated by 400 million years of evolution. Individual differences in anesthetic sensitivity and stochastic fluctuations in responsiveness complicate the ability to appropriately dose anesthetics to each individual. Identifying the biological substrate of noise, however, may spur novel therapies, assure consistent drug responses, and encourage the shift from population-based to personalized medicine.

scholarly journals Emergence of spatio-temporal variations in chemotherapeutic drug efficacy: in-vitro and in-Silico 3D tumour spheroid studies

BMC Cancer ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
M. V. Sheraton ◽  
G. G. Y. Chiew ◽  
V. Melnikov ◽  
E. Y. Tan ◽  
K. Q. Luo ◽  
...  
Keyword(s):  
Cell Population ◽  
Interaction Model ◽  
Drug Efficacy ◽  
Population Level ◽  
Temporal Variations ◽  
Spatial Effects ◽  
Drug Induced ◽  
Drug Actions ◽  
Spatio Temporal

Abstract Background The mechanisms of action and efficacy of cisplatin and paclitaxel at cell population level are well studied and documented, however the localized spatio-temporal effects of the drugs are less well understood. We explore the emergence of spatially preferential drug efficacy resulting from variations in mechanisms of cell-drug interactions. Methods 3D spheroids of HeLa-C3 cells were treated with drugs, cisplatin and paclitaxel. This was followed by sectioning and staining of the spheroids to track the spatio-temporal apoptotic effects of the drugs. A mechanistic drug-cell interaction model was developed and simulated to analyse the localized efficacy of these drugs. Results The outcomes of drug actions on a local cell population was dependant on the interactions between cell repair probability, intracellular drug concentration and cell’s mitosis phase. In spheroids treated with cisplatin, drug induced apoptosis is found to be scattered throughout the volume of the spheroids. In contrast, effect of paclitaxel is found to be preferentially localized along the periphery of the spheroids. Combinatorial treatments of cisplatin and paclitaxel result in varying levels of cell apoptosis based on the scheduling strategy. Conclusions The preferential action of paclitaxel can be attributed to the cell characteristics of the peripheral population. The model simulations and experimental data show that treatments initiated with paclitaxel are more efficacious due to the cascading of spatial effects of the drugs.

Randomised controlled trial of stand-alone tailored emails for smoking cessation

2017 ◽  
Vol 27 (2) ◽  
pp. 136-146 ◽  
Author(s):  
J Lee Westmaas ◽  
Jeuneviette Bontemps-Jones ◽  
Peter S Hendricks ◽  
Jihye Kim ◽  
Lorien C Abroms
Keyword(s):  
Smoking Cessation ◽  
Controlled Trial ◽  
Population Level ◽  
Data Sets ◽  
Quit Attempt ◽  
Quit Smoking ◽  
Large Numbers ◽  
And Gender ◽  
Randomised Controlled

IntroductionDigital technology has created opportunities for delivering smoking cessation assistance at the population level. However, the efficacy of sending multiple, automated, tailored emails providing motivation, support and information for quitting is unknown.MethodsSmokers planning to quit (n=1070) were randomly assigned to (1) 27 tailored cessation emails (deluxe email group (DEG)), (2) 3 to 4 tailored emails with links to downloadable booklets (basic email group (BEG)) or (3) a single non-tailored email (single email group (SEG)). All emails included links to quitting resources. Self-reported 7-day point-prevalence abstinence was assessed at 1 month, 3 months and 6 months postenrolment.ResultsAcross follow-ups, abstinence was significantly greater for smokers in the DEG (34%) compared with the SEG (25.8%; OR=1.47, 95% CI 1.07 to 2.02, p=0.02) but there was no difference between the BEG (30.8%) and the SEG (p=0.13). Results were independent of baseline cigarettes per day, interest in quitting, smoker in household, use of nicotine replacement therapy (NRT) or varenicline and gender, themselves associated with abstinence (ps<0.05). Missing=smoking and multiple imputation analyses based on 25 data sets corroborated results. Participants in the DEG were also more likely to use non-medication aids (eg, quit smoking website, cessation class/clinic) compared with the SEG (OR=1.34, p=0.02, CI 1.06 to 1.71), but use of these or NRT by the 4-week follow-up (vs no use) increased abstinence across follow-ups primarily for those in the SEG.ConclusionsStand-alone tailored, multiple emails providing support, motivation and information during a quit attempt are an easily deployable, inexpensive mode of providing effective cessation assistance to large numbers of smokers planning to quit.

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