scholarly journals Memory for spatio-temporal contextual details during the retrieval of naturalistic episodes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Samy-Adrien Foudil ◽  
Claire Pleche ◽  
Emiliano Macaluso
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Subjective Experience ◽  
Temporal Order ◽  
Subjective Memory ◽  
Scale Invariant ◽  
Wide Range ◽  
Spatio Temporal ◽  
Invariant Properties ◽  
Context Memory

AbstractEpisodic memory entails the storage of events together with their spatio-temporal context and retrieval comprises the subjective experience of a link between the person who remembers and the episode itself. We used an encoding procedure with mobile-phones to generate experimentally-controlled episodes in the real world: object-images were sent to the participants' phone, with encoding durations up to 3 weeks. In other groups of participants, the same objects were encoded during the exploration of a virtual town (45 min) or using a standard laboratory paradigm, with pairs of object/place-images presented in a sequence of unrelated trials (15 min). At retrieval, we tested subjective memory for the objects (remember/familiar) and memory for the context (place and time). We found that accurate and confident context-memory increased the likelihood of “remember” responses, in all encoding contexts. We also tested the participants' ability to judge the temporal-order of the encoded episodes. Using a model of temporal similarity, we demonstrate scale-invariant properties of order-retrieval, but also highlight the contribution of non-chronological factors. We conclude that the mechanisms governing episodic memory retrieval can operate across a wide range of spatio-temporal contexts and that the multi-dimensional nature of the episodic traces contributes to the subjective experience of retrieval.

scholarly journals Memory for Spatio-temporal Contextual Details During the Retrieval of Naturalistic Episodes

2021 ◽  
Author(s):  
Samy-Adrien Foudil ◽  
Claire Pleche ◽  
Emiliano Macaluso
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Subjective Experience ◽  
Temporal Order ◽  
Subjective Memory ◽  
Scale Invariant ◽  
Wide Range ◽  
Spatio Temporal ◽  
Invariant Properties ◽  
Context Memory

Abstract Episodic memory entails the storage of events together with their spatio-temporal context and retrieval comprises the subjective experience of a link between the person who remembers and the episode itself. We used an encoding procedure with mobile-phones to generate experimentally-controlled episodes in the real world: object-images were sent to the participants' phone, with encoding durations up to 3 weeks. In other groups of participants, the same objects were encoded during the exploration of a virtual town (45 min) or using a standard laboratory paradigm, with pairs of object/place-images presented in a sequence of unrelated trials (15 min). At retrieval, we tested subjective memory for the objects (remember/familiar) and memory for the context (place and time). We found that accurate and confident context-memory increased the likelihood of "remember" responses, in all encoding contexts. We also tested the participants' ability to judge the temporal-order of the encoded episodes. Using a model of temporal similarity, we demonstrate scale-invariant properties of order-retrieval, but also highlight the contribution of non-chronological factors. We conclude that the mechanisms governing episodic memory retrieval can operate across a wide range of spatio-temporal contexts and that the multi-dimensional nature of the episodic traces contributes to the subjective experience of retrieval.

scholarly journals Multifractal evaluation of simulated precipitation intensities from the COSMO NWP model

2017 ◽  
Author(s):  
Daniel Wolfensberger ◽  
Auguste Gires ◽  
Ioulia Tchiguirinskaia ◽  
Daniel Schertzer ◽  
Alexis Berne
Keyword(s):  
Multifractal Analysis ◽  
Dominant Role ◽  
Weather Prediction ◽  
Time Variability ◽  
Scale Invariant ◽  
Simulated Precipitation ◽  
Wide Range ◽  
Spatio Temporal ◽  
The Impact ◽  
Water Contents

Abstract. The framework of universal multifractals allows to characterize the spatio-temporal variability of fields over a wide range of scales with only a limited number of scale-invariant parameters. In this work, we perform a multifractal analysis of simulated fields of water contents in liquid, solid and gas phase from the COSMO numerical weather prediction model during three different events (one cold front associated with heavy snowfall, one stationary front with stratiform rain and one summer convection event) over Switzerland. The multifractal parameters of precipitation intensities at the ground are also compared with those obtained from the Swiss radar composite. The results of the analysis show that the COSMO simulations exhibit spatial scaling breaks that are not present in the radar data, indicating that the model is not able to simulate the observed variability at all scales. The impact of the topography on these conclusions was assessed by comparing a very steep area to a mostly flat area. It was observed that the topography does not seem to play a dominant role in the multifractal characterization of the COSMO water contents. Additionally, a spatio-temporal multifractal analysis of the COSMO simulations and the radar composite was performed and compared with a simplified scaling model of space-time variability.

scholarly journals The nucleus does not significantly affect the migratory trajectories of amoeba in two-dimensional environments

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ildefonso M. De la Fuente ◽  
Carlos Bringas ◽  
Iker Malaina ◽  
Benjamin Regner ◽  
Alberto Pérez-Samartín ◽  
...  
Keyword(s):  
Amoeba Proteus ◽  
Two Dimensional ◽  
Scale Invariant ◽  
Movement Trajectories ◽  
Physiological Processes ◽  
Wide Range ◽  
Unicellular Organisms ◽  
Positive Correlations ◽  
Step Fluctuations ◽  
Invariant Properties

Abstract For a wide range of cells, from bacteria to mammals, locomotion movements are a crucial systemic behavior for cellular life. Despite its importance in a plethora of fundamental physiological processes and human pathologies, how unicellular organisms efficiently regulate their locomotion system is an unresolved question. Here, to understand the dynamic characteristics of the locomotion movements and to quantitatively study the role of the nucleus in the migration of Amoeba proteus we have analyzed the movement trajectories of enucleated and non-enucleated amoebas on flat two-dimensional (2D) surfaces using advanced non-linear physical-mathematical tools and computational methods. Our analysis shows that both non-enucleated and enucleated amoebas display the same kind of dynamic migration structure characterized by highly organized data sequences, super-diffusion, non-trivial long-range positive correlations, persistent dynamics with trend-reinforcing behavior, and move-step fluctuations with scale invariant properties. Our results suggest that the presence of the nucleus does not significantly affect the locomotion of amoeba in 2D environments.

scholarly journals Replay of cortical spiking sequences during human memory retrieval

Science ◽  
2020 ◽  
Vol 367 (6482) ◽  
pp. 1131-1134 ◽  
Author(s):  
Alex P. Vaz ◽  
John H. Wittig ◽  
Sara K. Inati ◽  
Kareem A. Zaghloul
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Medial Temporal Lobe ◽  
Single Unit ◽  
Temporal Order ◽  
Human Memory ◽  
Memory Encoding ◽  
Human Cortex ◽  
Past Experiences ◽  
Specific Sequences

Episodic memory retrieval is thought to rely on the replay of past experiences, yet it remains unknown how human single-unit activity is temporally organized during episodic memory encoding and retrieval. We found that ripple oscillations in the human cortex reflect underlying bursts of single-unit spiking activity that are organized into memory-specific sequences. Spiking sequences occurred repeatedly during memory formation and were replayed during successful memory retrieval, and this replay was associated with ripples in the medial temporal lobe. Together, these data demonstrate that human episodic memory is encoded by specific sequences of neural activity and that memory recall involves reinstating this temporal order of activity.

scholarly journals Directional coupling of slow and fast hippocampal gamma with neocortical alpha/beta oscillations in human episodic memory

2019 ◽  
Vol 116 (43) ◽  
pp. 21834-21842 ◽  
Author(s):  
Benjamin J. Griffiths ◽  
George Parish ◽  
Frederic Roux ◽  
Sebastian Michelmann ◽  
Mircea van der Plas ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Memory Formation ◽  
Beta Power ◽  
Wide Range ◽  
Alpha Beta ◽  
Episodic Memories ◽  
Hippocampal Theta ◽  
Multisensory Information ◽  
Flow Of Information

Episodic memories hinge upon our ability to process a wide range of multisensory information and bind this information into a coherent, memorable representation. On a neural level, these 2 processes are thought to be supported by neocortical alpha/beta desynchronization and hippocampal theta/gamma synchronization, respectively. Intuitively, these 2 processes should couple to successfully create and retrieve episodic memories, yet this hypothesis has not been tested empirically. We address this by analyzing human intracranial electroencephalogram data recorded during 2 associative memory tasks. We find that neocortical alpha/beta (8 to 20 Hz) power decreases reliably precede and predict hippocampal “fast” gamma (60 to 80 Hz) power increases during episodic memory formation; during episodic memory retrieval, however, hippocampal “slow” gamma (40 to 50 Hz) power increases reliably precede and predict later neocortical alpha/beta power decreases. We speculate that this coupling reflects the flow of information from the neocortex to the hippocampus during memory formation, and hippocampal pattern completion inducing information reinstatement in the neocortex during memory retrieval.

scholarly journals Multifractal evaluation of simulated precipitation intensities from the COSMO NWP model

2017 ◽  
Vol 17 (23) ◽  
pp. 14253-14273 ◽  
Author(s):  
Daniel Wolfensberger ◽  
Auguste Gires ◽  
Ioulia Tchiguirinskaia ◽  
Daniel Schertzer ◽  
Alexis Berne
Keyword(s):  
Extreme Values ◽  
Weather Prediction ◽  
Radar Data ◽  
Numerical Weather Prediction Model ◽  
Scale Invariant ◽  
Simulated Precipitation ◽  
Wide Range ◽  
Synoptic Conditions ◽  
Spatio Temporal ◽  
Nwp Model

Abstract. The framework of universal multifractals (UM) characterizes the spatio-temporal variability in geophysical data over a wide range of scales with only a limited number of scale-invariant parameters. This work aims to clarify the link between multifractals (MFs) and more conventional weather descriptors and to show how they can be used to perform a multi-scale evaluation of model data. The first part of this work focuses on a MF analysis of the climatology of precipitation intensities simulated by the COSMO numerical weather prediction model. Analysis of the spatial structure of the MF parameters, and their correlations with external meteorological and topographical descriptors, reveals that simulated precipitation tends to be smoother at higher altitudes, and that the mean intermittency is mostly influenced by the latitude. A hierarchical clustering was performed on the external descriptors, yielding three different clusters, which correspond roughly to Alpine/continental, Mediterranean and temperate regions. Distributions of MF parameters within these three clusters are shown to be statistically significantly different, indicating that the MF signature of rain is indeed geographically dependent. The second part of this work is event-based and focuses on the smaller scales. The MF parameters of precipitation intensities at the ground are compared with those obtained from the Swiss radar composite during three events corresponding to typical synoptic conditions over Switzerland. The results of this analysis show that the COSMO simulations exhibit spatial scaling breaks that are not present in the radar data, indicating that the model is not able to simulate the observed variability at all scales. A comparison of the operational one-moment microphysical parameterization scheme of COSMO with a more advanced two-moment scheme reveals that, while no scheme systematically outperforms the other, the two-moment scheme tends to produce larger extreme values and more discontinuous precipitation fields, which agree better with the radar composite.

scholarly journals Directional coupling of slow and fast hippocampal gamma with neocortical alpha/beta oscillations in human episodic memory

2018 ◽  
Author(s):  
Benjamin J. Griffiths ◽  
George Parish ◽  
Frederic Roux ◽  
Sebastian Michelmann ◽  
Mircea van der Plas ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Division Of Labour ◽  
Memory Formation ◽  
Beta Power ◽  
Wide Range ◽  
Directional Coupling ◽  
Alpha Beta ◽  
Episodic Memories ◽  
Flow Of Information

AbstractEpisodic memories hinge upon our ability to process a wide range of multisensory information and bind this information into a coherent, memorable representation. On a neural level, these two processes are thought to be supported by neocortical alpha/beta desynchronisation and hippocampal theta/gamma synchronisation, respectively. Intuitively, these two processes should couple to successfully create and retrieve episodic memories, yet this hypothesis has not been tested empirically. We address this by analysing human intracranial EEG data recorded during two associative memory tasks. We find that neocortical alpha/beta (8-20Hz) power decreases reliably precede and predict hippocampal “fast” gamma (60-80Hz) power increases during episodic memory formation; during episodic memory retrieval however, hippocampal “slow” gamma (40-50Hz) power increases reliably precede and predict later neocortical alpha/beta power decreases. We speculate that this coupling reflects the flow of information from neocortex to hippocampus during memory formation, and hippocampal pattern completion inducing information reinstatement in the neocortex during memory retrieval.Significance StatementEpisodic memories detail our personally-experienced past. The formation and retrieval of these memories has long been thought to be supported by a division of labour between the neocortex and the hippocampus, where the former processes event-related information and the latter binds this information together. However, it remains unclear how the two regions interact. We uncover directional coupling between these regions, with power decreases in the neocortex that precede and predict power increases in the hippocampus during memory formation. Fascinatingly, this process reverses during memory retrieval, with hippocampal power increases preceding and predicting neocortical power decreases. These results suggest a bidirectional flow of information between the neocortex and hippocampus is fundamental to the formation and retrieval of episodic memories.

scholarly journals Set-relevance Determines the Impact of Distractors on Episodic Memory Retrieval

2014 ◽  
Vol 26 (9) ◽  
pp. 2070-2086 ◽  
Author(s):  
Sze Chai Kwok ◽  
Tim Shallice ◽  
Emiliano Macaluso
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Temporal Order ◽  
Memory Search ◽  
Attention And Memory ◽  
Attention Network ◽  
Temporal Proximity ◽  
Imaging Results ◽  
The Right ◽  
The Impact

We investigated the interplay between stimulus-driven attention and memory retrieval with a novel interference paradigm that engaged both systems concurrently on each trial. Participants encoded a 45-min movie on Day 1 and, on Day 2, performed a temporal order judgment task during fMRI. Each retrieval trial comprised three images presented sequentially, and the task required participants to judge the temporal order of the first and the last images (“memory probes”) while ignoring the second image, which was task irrelevant (“attention distractor”). We manipulated the content relatedness and the temporal proximity between the distractor and the memory probes, as well as the temporal distance between two probes. Behaviorally, short temporal distances between the probes led to reduced retrieval performance. Distractors that at encoding were temporally close to the first probe image reduced these costs, specifically when the distractor was content unrelated to the memory probes. The imaging results associated the distractor probe temporal proximity with activation of the right ventral attention network. By contrast, the precuneus was activated for high-content relatedness between distractors and probes and in trials including a short distance between the two memory probes. The engagement of the right ventral attention network by specific types of distractors suggests a link between stimulus-driven attention control and episodic memory retrieval, whereas the activation pattern of the precuneus implicates this region in memory search within knowledge/content-based hierarchies.

scholarly journals Assessment of Behavioural Markers of Autonoetic Consciousness during Episodic Autobiographical Memory Retrieval: A Preliminary Analysis

2008 ◽  
Vol 19 (1-2) ◽  
pp. 3-6 ◽  
Author(s):  
M. Irish ◽  
B. A. Lawlor ◽  
S. M. O'Mara ◽  
R. F. Coen
Keyword(s):  
Episodic Memory ◽  
Autobiographical Memory ◽  
Memory Retrieval ◽  
Preliminary Analysis ◽  
Subjective Experience ◽  
Episodic Retrieval ◽  
Memory Assessment ◽  
Test Instrument ◽  
Autonoetic Consciousness ◽  
Original Event

There is ongoing theoretical debate regarding episodic memory and how it can be accurately measured, in particular if the focus should be content-based recall of episodic details or something more experiential involving the subjective capacity to mentally travel back in time and “re-live” aspects of the original event. The autonoetic subscale of the Episodic Autobiographical Memory Interview (EAMI) is presented here as a new test instrument that attempts to redress theoretical and methodological shortcomings in autobiographical memory assessment. The EAMI merges a phenomenological detail-based approach with an assessment of autonoetic consciousness, departing considerably from traditional Remember/Know paradigms used within this field. We present findings from an initial pilot study investigating the potential markers of autonoetic consciousness that may accompany episodic retrieval. Key behavioural indices of autonoetic consciousness, notably those of viewer perspective, visual imagery, and emotional re-experiencing, emerged as being inextricably bound with the level of phenomenological detail recalled and the overall re-living judgment. The autonoetic subscale of the EAMI permits conceptually refined assessment of episodic personal memories and the accompanying subjective experience of mental re-living, characteristic of episodic memory.

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