scholarly journals Extended experience reveals distinct representational dynamics governing the CA1 spatial code

2021 ◽  
Author(s):  
Alexandra T. Keinath ◽  
Coralie-Anne Mosser ◽  
Mark P. Brandon
Keyword(s):  
Episodic Memory ◽  
Calcium Imaging ◽  
Prior Experience ◽  
Representational Content ◽  
Spatial Code ◽  
Time Varying ◽  
Short Term ◽  
Neural Ensembles ◽  
Free Exploration

SummaryHippocampal subregion CA1 is thought to support episodic memory by reinstating a stable spatial code. However, recent calcium imaging experiments have challenged this presumed function by demonstrated that this code is largely unstable on a timescale of days. This turnover may reflect homogenous drift within the population; alternatively, it may reflect distinct time-varying representational component(s) which coexists alongside other stable components. Here we characterized the mouse CA1 spatial code over more than a month of daily free exploration experience in an extended geometric morph paradigm. We find that this code is governed by distinct representational components with different long-term dynamics, including stable components representing the shape of space and prior experience. These components are mediated by separate neural ensembles with similar short-term spatial reliability and precision. Together, these results demonstrate that the long-term dynamics of the CA1 spatial code are defined by representational content, not homogenous drift.

Representational content determines the long-term dynamics of the CA1 spatial code

2021 ◽  
Author(s):  
Alexandra Keinath ◽  
Coralie-Anne Mosser ◽  
Mark Brandon
Keyword(s):  
Episodic Memory ◽  
Prior Experience ◽  
Representational Content ◽  
Spatial Code ◽  
Time Varying ◽  
Short Term ◽  
Daily Experience ◽  
Neural Ensembles ◽  
Spatial Geometry

Abstract Hippocampal subregion CA1 is thought to support episodic memory by reinstating a stable spatial code. Yet recent experiments have demonstrated that this code is largely unstable on a timescale of days, challenging its presumed function. While these dynamics may indeed reflect homogenous drift within the population, they may alternatively reflect distinct time-varying representational component(s) which coexists alongside other stable components. Here we adjudicate between these possibilities. To this end, we characterized the mouse CA1 spatial code over more than a month of daily experience in an extended geometric morph paradigm. We find that this code is governed by distinct representational components with different long-term dynamics, including stable components representing spatial geometry and prior experience. These components are mediated by separate neural ensembles with similar short-term spatial reliability and precision. Together, these results demonstrate that the long-term dynamics of the CA1 spatial code are defined by representational content, not homogenous drift.

scholarly journals All insects are equal, but some insects are more equal than others

2018 ◽  
Vol 120 (4) ◽  
pp. 852-863 ◽  
Author(s):  
Arnout R.H. Fischer ◽  
L.P.A. (Bea) Steenbekkers
Keyword(s):  
Design Methodology ◽  
Prior Experience ◽  
Future Research ◽  
Valuable Contribution ◽  
Short Term ◽  
Content Type ◽  
Quasi Experimental ◽  
Insects As Food ◽  
Practical Implications

Purpose Lack of acceptance of insects as food is considered a barrier against societal adoption of the potentially valuable contribution of insects to human foods. An underlying barrier may be that insects are lumped together as one group, while consumers typically try specific insects. The purpose of this paper is to investigate the ways in which Dutch consumers, with and without insect tasting experience, are more or less willing to eat different insects. Design/methodology/approach In a quasi-experimental study (n=140), the participants with and without prior experience in eating insects were asked to give their willingness to eat a range of insects, and their attitudes and disgust towards eating insects. Findings Insects promoted in the market were more preferred than the less marketed insects, and a subgroup of preferred insects for participants with experience in eating insects was formed. Research limitations/implications Although well-known insects were more preferred, general willingness to eat remained low for all participants. The results indicate that in future research on insects as food the specific insects used should be taken into account. Practical implications Continued promotion of specific, carefully targeted, insects may not lead to short-term uptake of insects as food, but may contribute to willingness to eat insects as human food in the long term. Originality/value The paper shows substantial differences between consumers who have and who have not previously tasted insects, with higher acceptance of people with experience in tasting insects for the specific insects that are frequently promoted beyond their generally more positive attitude towards eating insects.

scholarly journals Time-Varying Network Connectedness of G-7 Economic Policy Uncertainties: A Locally Stationary TVP-VAR Approach

2021 ◽  
Vol 7 (2) ◽  
pp. 47-59
Author(s):  
Onur Polat
Keyword(s):  
Economic Policy ◽  
Global Financial Crisis ◽  
Dynamic Networks ◽  
Time Varying ◽  
Short Term ◽  
Frequency Dependent ◽  
Vector Autoregressive ◽  
Network Connectedness ◽  
The Global Financial Crisis

This work analyzes the frequency-dependent network structure of Economic Policy Uncertainties (EPU) across G-7 countries between January 1998 and April 2021. We implement an approach that builds dynamic networks relying on a locally stationary Time-Varying Parameter-Vector Autoregressive model using Quasi-Bayesian Local Likelihood methods. We compute short-, medium-, and long-term network connectedness of G-7 EPUs over a period covering several economic/financial turmoils. Furthermore, we structure short-term network topologies for the Global Financial Crisis (GFC) and the COVID-19 pandemic periods. Findings of the study indicate amplified interdependencies between G-7 EPUs around well-known economic/geopolitical incidents, frequency-dependent connectedness networks among them, and stronger interdependencies than the medium-, and long-term linkages. Finally, we find that short-term spillovers are not persistent in the long-term for both turmoil periods.

Distributed Stochastic Power Control for Time-Varying Long-Term and Short-Term Fading Wireless Networks

2007 ◽  
Author(s):  
Mohammed M. Olama ◽  
Seddik M. Djouadi ◽  
Charalambos D. Charalambous ◽  
Samir Sahyoun
Keyword(s):  
Wireless Networks ◽  
Power Control ◽  
Time Varying ◽  
Short Term

Variance Reduction in Analytical Processes in the Clinical Laboratory by Digital Filtering

1983 ◽  
Vol 20 (3) ◽  
pp. 174-181 ◽  
Author(s):  
R T P Jansen ◽  
P J M Bonants
Keyword(s):  
Variance Reduction ◽  
Clinical Laboratory ◽  
Digital Filtering ◽  
Process Variations ◽  
Mean Value ◽  
Time Varying ◽  
Short Term ◽  
Serum Samples ◽  
Filtering Procedure

A model is postulated describing the fluctuations in analytical chemical processes in the clinical laboratory. In this model the process variations are described by a non-stationary stochastic process with a significant time-varying mean value. Experiments demonstrate a short-term variance within a run and a long-term variance between runs determined by the time-varying mean value. For four different analytical systems used for determining six serum analytes between-run variance was demonstrated to be significantly greater than within-run variance. Based on the model a digital filtering procedure is presented which in each run estimates the process mean and subsequently corrects serum samples for its deviation. Thus significant variance reductions are obtained. The filtering procedure was tested for the determination in inorganic phosphate with a continuous-flow system in an experimental environment.

scholarly journals Surgical vs Natural Menopause: Cognitive Issues

2014 ◽  
Vol 2 (1) ◽  
pp. 54-55
Author(s):  
VW Henderson ◽  
BB Sherwin
Keyword(s):  
Clinical Trial ◽  
Episodic Memory ◽  
Hormone Therapy ◽  
Cognitive Skills ◽  
High Dose ◽  
Short Term ◽  
Natural Menopause ◽  
Surgical Menopause ◽  
Cognitive Consequences

Abstract Objective Women who undergo both natural and surgical menopause experience the loss of cyclic ovarian production of estrogen, but hormonal and demographic differences distinguish these two groups of women. Our objective was to review published evidence on whether the premature cessation of endogenous estrogen production in women who underwent a surgical menopause has deleterious consequences for cognitive aging and to determine whether consequences differ for women if they undergo natural menopause. Studies of estrogen-containing hormone therapy are relevant to this issue. Design We reviewed evidence-based research, including the systematic identification of randomized clinical trials of hormone therapy with cognitive outcomes that included an objective measure of episodic memory. Results As inferred from very small, short-term, randomized, controled trials of high-dose estrogen treatment, surgical menopause may be accompanied by cognitive impairment that primarily affects verbal episodic memory. Observational evidence suggests that the natural menopausal transition is not accompanied by substantial changes in cognitive abilities. For initiation of hormone therapy during perimenopause or early postmenopause when the ovaries are intact, limited clinical trial data provide no consistent evidence of short-term benefit or harm. There is stronger clinical trial evidence that initiation of hormone therapy in late postmenopause does not benefit episodic memory or other cognitive skills. Conclusion Further research is needed on the long-term cognitive consequences of surgical menopause and long-term cognitive consequences of hormone therapy initiated near the time of surgical or natural menopause. A potential short-term cognitive benefit might be weighed when a premenopausal woman considers initiation of estrogen therapy at the time of, or soon after, hysterectomy and oophorectomy for benign conditions, although data are still quite limited and estrogen is not approved for this indication. Older postmenopausal women should not initiate hormone therapy to improve or maintain cognitive skills.

Experimental Effects of Acute Exercise on Episodic Memory Function: Considerations for the Timing of Exercise

2018 ◽  
Vol 122 (5) ◽  
pp. 1744-1754 ◽  
Author(s):  
James T. Haynes ◽  
Emily Frith ◽  
Eveleen Sng ◽  
Paul D. Loprinzi
Keyword(s):  
Episodic Memory ◽  
Prospective Memory ◽  
Acute Exercise ◽  
Memory Function ◽  
Moderate Intensity ◽  
Long Term Memory ◽  
Memory Encoding ◽  
Short Term ◽  
Term Memory

Our previous work employing a between-subject randomized controlled trial design suggests that exercising prior to memory encoding is more advantageous in enhancing retrospective episodic memory function when compared to exercise occurring during or after memory encoding. The present experiment evaluates this potential temporal effect of acute exercise on memory function while employing a within-subject, counterbalanced design. In a counterbalanced order (via Latin squares), 24 participants completed four visits including (1) exercising (moderate-intensity walking) prior to memory encoding, (2) exercising during memory encoding, (3) exercising after memory encoding, and (4) a control visit (no exercise). Retrospective memory function (short term and long term; 24-hour follow-up) was assessed from a multitrial word list. Prospective memory was assessed from a time-based task. Compared to all other visits, short-term memory was greater in the visit that involved exercising prior to memory encoding (F = 3.76; P = .01; η2 = .79). Similar results occurred for long-term memory, with no significant effects for prospective memory performance. We provide robust evidence demonstrating that acute moderate-intensity exercise prior to memory encoding is optimal in enhancing short-term and long-term memory function when compared to no exercise as well as exercising during and after memory encoding.

The Role of Memory in Communication

2020 ◽  
pp. 33-54
Author(s):  
Alison Wray
Keyword(s):  
Episodic Memory ◽  
Sense Of Self ◽  
Memory Deficits ◽  
Event Memory ◽  
Short Term ◽  
The Impact

This chapter explores the nature of memory and the impact on communication of the memory deficits associated with dementia. The main types of memory are described (long-term, short-term, working, declarative, implicit, emotional, episodic). The process of recalling information is discussed, and the natural changes associated with ageing are considered. The general impact on communication of impaired event memory is explored before a deeper look is taken at why disruption to episodic memory has such a significant impact on communication. Specifically, the role of autonoesis (knowing one was present at an event) is explored. Without autonoesis, it is harder to speak with authority and confidence about what happened. People living with a dementia are vulnerable to being doubted, out-argued, and shouted down by those able to produce a stronger case for their own claims. Not being believed is a significant assault on the sense of self.

Sign in / Sign up

Export Citation Format

Share Document