scholarly journals Internal representation of hippocampal neuronal population span a time-distance continuum

2018 ◽  
Author(s):  
Caroline Haimerl ◽  
David Angulo-Garcia ◽  
Vincent Villette ◽  
Susanne. Reichinnek ◽  
Alessandro Torcini ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Temporal Integration ◽  
Critical Role ◽  
Experimental Studies ◽  
Cell Activity ◽  
Network Activity ◽  
Time And Space ◽  
Distance Information ◽  
Space And Time ◽  
Spatio Temporal

AbstractThe hippocampus plays a critical role in episodic memory: the sequential representation of visited places and experienced events. This function is mirrored by hippocampal activity that self organizes into sequences of neuronal activation that integrate spatio-temporal information. What are the underlying mechanisms of such integration is still unknown. Single cell activity was recently shown to combine time and distance information; however, it remains unknown whether a degree of tuning between space and time can be defined at the network level. Here, combining daily calcium imaging of CA1 sequence dynamics in running head-fixed mice and network modeling, we show that CA1 network activity tends to represent a specific combination of space and time at any given moment, and that the degree of tuning can shift within a continuum from one day to the next. Our computational model shows that this shift in tuning can happen under the control of the external drive power. We propose that extrinsic global inputs shape the nature of spatio-temporal integration in the hippocampus at the population level depending on the task at hand, a hypothesis which may guide future experimental studies.Significance StatementThe hippocampus organizes experience in sequences of events that form episodic memory. How are time and space internally computed in the hippocampus in the absence of sequential external inputs? Here we show that time and space are integrated together within the hippocampal network with different degrees of tuning across days. This was found by recording the activity of hundreds of pyramidal cells for several days. We also propose a mechanism supporting such spatio-temporal integration based on a ring attractor network model: the degree of tuning between space and time can be adjusted by modulating the power of a non-sequential external excitatory drive. In this way, the hippocampus is able to generate a spatio-temporal representation tuned to the task at hand.

scholarly journals Internal representation of hippocampal neuronal population spans a time-distance continuum

2019 ◽  
Vol 116 (15) ◽  
pp. 7477-7482 ◽  
Author(s):  
Caroline Haimerl ◽  
David Angulo-Garcia ◽  
Vincent Villette ◽  
Susanne Reichinnek ◽  
Alessandro Torcini ◽  
...  
Keyword(s):  
Critical Role ◽  
Experimental Studies ◽  
Cell Activity ◽  
Internal Representation ◽  
Population Level ◽  
Neuronal Population ◽  
Network Activity ◽  
Drive Power ◽  
Distance Information ◽  
Space And Time

The hippocampus plays a critical role in episodic memory: the sequential representation of visited places and experienced events. This function is mirrored by hippocampal activity that self organizes into sequences of neuronal activation that integrate spatiotemporal information. What are the underlying mechanisms of such integration is still unknown. Single cell activity was recently shown to combine time and distance information; however, it remains unknown whether a degree of tuning between space and time can be defined at the network level. Here, combining daily calcium imaging of CA1 sequence dynamics in running head-fixed mice and network modeling, we show that CA1 network activity tends to represent a specific combination of space and time at any given moment, and that the degree of tuning can shift within a continuum from 1 day to the next. Our computational model shows that this shift in tuning can happen under the control of the external drive power. We propose that extrinsic global inputs shape the nature of spatiotemporal integration in the hippocampus at the population level depending on the task at hand, a hypothesis which may guide future experimental studies.

scholarly journals Glutamate-Bound NMDARs Arising from In Vivo-like Network Activity Extend Spatio-temporal Integration in a L5 Cortical Pyramidal Cell Model

2014 ◽  
Vol 10 (4) ◽  
pp. e1003590 ◽  
Author(s):  
Matteo Farinella ◽  
Daniel T. Ruedt ◽  
Padraig Gleeson ◽  
Frederic Lanore ◽  
R. Angus Silver
Keyword(s):  
Pyramidal Cell ◽  
Cell Model ◽  
Temporal Integration ◽  
Network Activity ◽  
Spatio Temporal ◽  
Cortical Pyramidal Cell

scholarly journals The Role of Hierarchical Dynamical Functions in Coding for Episodic Memory and Cognition

2019 ◽  
Vol 31 (9) ◽  
pp. 1271-1289 ◽  
Author(s):  
Holger Dannenberg ◽  
Andrew S. Alexander ◽  
Jennifer C. Robinson ◽  
Michael E. Hasselmo
Keyword(s):  
Episodic Memory ◽  
Verbal Memory ◽  
Memory Function ◽  
Single Agent ◽  
Human Cognition ◽  
Space And Time ◽  
Neurophysiological Data ◽  
Spatio Temporal ◽  
Stimulus Features ◽  
Definition Of

Behavioral research in human verbal memory function led to the initial definition of episodic memory and semantic memory. A complete model of the neural mechanisms of episodic memory must include the capacity to encode and mentally reconstruct everything that humans can recall from their experience. This article proposes new model features necessary to address the complexity of episodic memory encoding and recall in the context of broader cognition and the functional properties of neurons that could contribute to this broader scope of memory. Many episodic memory models represent individual snapshots of the world with a sequence of vectors, but a full model must represent complex functions encoding and retrieving the relations between multiple stimulus features across space and time on multiple hierarchical scales. Episodic memory involves not only the space and time of an agent experiencing events within an episode but also features shown in neurophysiological data such as coding of speed, direction, boundaries, and objects. Episodic memory includes not only a spatio-temporal trajectory of a single agent but also segments of spatio-temporal trajectories for other agents and objects encountered in the environment consistent with data on encoding the position and angle of sensory features of objects and boundaries. We will discuss potential interactions of episodic memory circuits in the hippocampus and entorhinal cortex with distributed neocortical circuits that must represent all features of human cognition.

scholarly journals An event map of memory space in the hippocampus

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Lorena Deuker ◽  
Jacob LS Bellmund ◽  
Tobias Navarro Schröder ◽  
Christian F Doeller
Keyword(s):  
Episodic Memory ◽  
Large Scale ◽  
De Novo ◽  
Common Mechanism ◽  
Memory Space ◽  
Common Coding ◽  
Space And Time ◽  
Temporal Aspects ◽  
Neural Event ◽  
Spatio Temporal

The hippocampus has long been implicated in both episodic and spatial memory, however these mnemonic functions have been traditionally investigated in separate research strands. Theoretical accounts and rodent data suggest a common mechanism for spatial and episodic memory in the hippocampus by providing an abstract and flexible representation of the external world. Here, we monitor the de novo formation of such a representation of space and time in humans using fMRI. After learning spatio-temporal trajectories in a large-scale virtual city, subject-specific neural similarity in the hippocampus scaled with the remembered proximity of events in space and time. Crucially, the structure of the entire spatio-temporal network was reflected in neural patterns. Our results provide evidence for a common coding mechanism underlying spatial and temporal aspects of episodic memory in the hippocampus and shed new light on its role in interleaving multiple episodes in a neural event map of memory space.

The capacity of short term memory from an evolutionary perspective

2019 ◽  
Author(s):  
Majid Manoochehri
Keyword(s):  
Short Term Memory ◽  
Memory Span ◽  
Critical Role ◽  
Experimental Studies ◽  
Cognitive System ◽  
Evolutionary Approach ◽  
Evolutionary Perspective ◽  
Short Term ◽  
Term Memory

Memory span in humans has been intensely studied for more than a century. In spite of the critical role of memory span in our cognitive system, which intensifies the importance of fundamental determinants of its evolution, few studies have investigated it by taking an evolutionary approach. Overall, we know hardly anything about the evolution of memory components. In the present study, I briefly review the experimental studies of memory span in humans and non-human animals and shortly discuss some of the relevant evolutionary hypotheses.

LncRNA SNHG12 Improves Cerebral Ischemic-reperfusion Injury by Activating SIRT1/FOXO3a Pathway through I nhibition of Autophagy and Oxidative Stress

2020 ◽  
Vol 17 (4) ◽  
pp. 394-401
Author(s):  
Yuanhua Wu ◽  
Yuan Huang ◽  
Jing Cai ◽  
Donglan Zhang ◽  
Shixi Liu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Molecular Mechanisms ◽  
Ischemia Reperfusion ◽  
Critical Role ◽  
Cell Activity ◽  
Ht22 Cells ◽  
Cerebral Ischemic ◽  
Cerebral Ischemic Reperfusion ◽  
And Oxidative Stress

Background: Ischemia/reperfusion (I/R) injury involves complex biological processes and molecular mechanisms such as autophagy. Oxidative stress plays a critical role in the pathogenesis of I/R injury. LncRNAs are the regulatory factor of cerebral I/R injury. Methods: This study constructs cerebral I/R model to investigate role of autophagy and oxidative stress in cerebral I/R injury and the underline regulatory mechanism of SIRT1/ FOXO3a pathway. In this study, lncRNA SNHG12 and FOXO3a expression was up-regulated and SIRT1 expression was down-regulated in HT22 cells of I/R model. Results: Overexpression of lncRNA SNHG12 significantly increased the cell viability and inhibited cerebral ischemicreperfusion injury induced by I/Rthrough inhibition of autophagy. In addition, the transfected p-SIRT1 significantly suppressed the release of LDH and SOD compared with cells co-transfected with SIRT1 and FOXO3a group and cells induced by I/R and transfected with p-SNHG12 group and overexpression of cells co-transfected with SIRT1 and FOXO3 further decreased the I/R induced release of ROS and MDA. Conclusion: In conclusion, lncRNA SNHG12 increased cell activity and inhibited oxidative stress through inhibition of SIRT1/FOXO3a signaling-mediated autophagy in HT22 cells of I/R model. This study might provide new potential therapeutic targets for further investigating the mechanisms in cerebral I/R injury and provide.

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