scholarly journals Sequence Memory in the Hippocampal–Entorhinal Region

2020 ◽  
Vol 32 (11) ◽  
pp. 2056-2070 ◽  
Author(s):  
Jacob L. S. Bellmund ◽  
Ignacio Polti ◽  
Christian F. Doeller
Keyword(s):  
Entorhinal Cortex ◽  
Relational Networks ◽  
Sequence Of Events ◽  
Entorhinal Region ◽  
Temporal Relationships ◽  
Organizational Principle ◽  
Ongoing Behavior ◽  
Sequence Memory ◽  
Episodic Memories

Episodic memories are constructed from sequences of events. When recalling such a memory, we not only recall individual events, but we also retrieve information about how the sequence of events unfolded. Here, we focus on the role of the hippocampal–entorhinal region in processing and remembering sequences of events, which are thought to be stored in relational networks. We summarize evidence that temporal relations are a central organizational principle for memories in the hippocampus. Importantly, we incorporate novel insights from recent studies about the role of the adjacent entorhinal cortex in sequence memory. In rodents, the lateral entorhinal subregion carries temporal information during ongoing behavior. The human homologue is recruited during memory recall where its representations reflect the temporal relationships between events encountered in a sequence. We further introduce the idea that the hippocampal–entorhinal region might enable temporal scaling of sequence representations. Flexible changes of sequence progression speed could underlie the traversal of episodic memories and mental simulations at different paces. In conclusion, we describe how the entorhinal cortex and hippocampus contribute to remembering event sequences—a core component of episodic memory.

scholarly journals Contextual Prediction Errors Reorganize Naturalistic Episodic Memories in Time

2021 ◽  
Author(s):  
Fahd Yazin ◽  
Moumita Das ◽  
Arpan Banerjee ◽  
Dipanjan Roy
Keyword(s):  
Declarative Memory ◽  
Prediction Errors ◽  
Decision Threshold ◽  
Time Dimension ◽  
Drift Diffusion ◽  
Temporal Domain ◽  
Sequence Memory ◽  
Episodic Memories ◽  
Adaptive Role

Abstract Episodic memories are contextual experiences ordered in time. This is underpinned by associative binding between events within the same contexts. The role of prediction errors in declarative memory is well established but has not been investigated in the time dimension of complex episodic memories. Here we combine these two properties of episodic memory, extend them into the temporal domain and demonstrate that prediction errors in different naturalistic contexts lead to changes in the temporal ordering of event structures in them. The wrongly predicted older sequences were weakened despite reactivating them after. Interestingly, the newly encoded sequences with prediction errors, seen once, showed as high accuracy as control sequences which were viewed repeatedly without change. Drift-diffusion modelling revealed a lower decision threshold for the newer sequences compared to older sequences, reflected by their faster recall. Moreover participants’ adjustments to their decision threshold could significantly predict their relative speed of sequence memory recall. This suggests a temporally distinct and adaptive role for prediction errors in learning and reorganizing episodic sequences.

scholarly journals Structuring Time in Human Lateral Entorhinal Cortex

2018 ◽  
Author(s):  
Jacob L.S. Bellmund ◽  
Lorena Deuker ◽  
Christian F. Doeller
Keyword(s):  
Episodic Memory ◽  
Entorhinal Cortex ◽  
Memory Retrieval ◽  
Temporal Structure ◽  
Event Structure ◽  
Temporal Memory ◽  
Event Sequences ◽  
Entorhinal Region ◽  
Virtual City

AbstractRemembering event sequences is central to episodic memory and thought to be supported by the hippocampal-entorhinal region. We previously demonstrated that the hippocampus maps spatial and temporal distances between events encountered along a fixed route through a virtual city (Deuker et al., 2016), but the content of entorhinal mnemonic representations remains unclear. Here, we demonstrate that, after learning, multi-voxel representations in the anterior-lateral entorhinal cortex (alEC) specifically reflect the temporal event structure. Holistic representations of the temporal structure related to memory recall and the temporal event structure could be reconstructed from entorhinal multi-voxel patterns. Our findings demonstrate representations of temporal structure in the alEC in line with temporal information carried by population signals in the lateral entorhinal cortex of navigating rodents and activations of its human homologue during temporal memory retrieval. Our results provide novel evidence for the role of the human alEC in representing time for episodic memory.

scholarly journals Contextual prediction errors reorganize naturalistic episodic memories in time

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fahd Yazin ◽  
Moumita Das ◽  
Arpan Banerjee ◽  
Dipanjan Roy
Keyword(s):  
Declarative Memory ◽  
Prediction Errors ◽  
Decision Threshold ◽  
Time Dimension ◽  
Temporal Domain ◽  
Sequence Memory ◽  
Episodic Memories ◽  
Temporal Sequences ◽  
Adaptive Role

AbstractEpisodic memories are contextual experiences ordered in time. This is underpinned by associative binding between events within the same contexts. The role of prediction errors in declarative memory is well established but has not been investigated in the time dimension of complex episodic memories. Here we combine these two properties of episodic memory, extend them into the temporal domain and demonstrate that prediction errors in different naturalistic contexts lead to changes in the temporal ordering of event structures in them. The wrongly predicted older sequences were weakened despite their reactivation. Interestingly the newly encoded sequences with prediction errors, seen once, showed accuracy as high as control sequences which were viewed repeatedly without change. Drift–diffusion modelling revealed a lower decision threshold for the newer sequences than older sequences, reflected by their faster recall. Moreover, participants’ adjustments to their decision threshold significantly correlated with their relative speed of sequence memory recall. These results suggest a temporally distinct and adaptive role for prediction errors in learning and reorganizing episodic temporal sequences.

scholarly journals What Is the Metabolic Amplification of Insulin Secretion and Is It (Still) Relevant?

Metabolites ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 355
Author(s):  
Ingo Rustenbeck ◽  
Torben Schulze ◽  
Mai Morsi ◽  
Mohammed Alshafei ◽  
Uwe Panten
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Adenine Nucleotides ◽  
Pancreatic Beta Cell ◽  
Secretory Response ◽  
Mitochondrial Activity ◽  
Insulin Synthesis ◽  
Sequence Of Events ◽  
Insulin Granules

The pancreatic beta-cell transduces the availability of nutrients into the secretion of insulin. While this process is extensively modified by hormones and neurotransmitters, it is the availability of nutrients, above all glucose, which sets the process of insulin synthesis and secretion in motion. The central role of the mitochondria in this process was identified decades ago, but how changes in mitochondrial activity are coupled to the exocytosis of insulin granules is still incompletely understood. The identification of ATP-sensitive K+-channels provided the link between the level of adenine nucleotides and the electrical activity of the beta cell, but the depolarization-induced Ca2+-influx into the beta cells, although necessary for stimulated secretion, is not sufficient to generate the secretion pattern as produced by glucose and other nutrient secretagogues. The metabolic amplification of insulin secretion is thus the sequence of events that enables the secretory response to a nutrient secretagogue to exceed the secretory response to a purely depolarizing stimulus and is thus of prime importance. Since the cataplerotic export of mitochondrial metabolites is involved in this signaling, an orienting overview on the topic of nutrient secretagogues beyond glucose is included. Their judicious use may help to define better the nature of the signals and their mechanism of action.

Peripheral muscarinic control of norepinephrine release in the cardiovascular system

1980 ◽  
Vol 239 (6) ◽  
pp. H713-H720 ◽  
Author(s):  
E. Muscholl
Keyword(s):  
Physiological Role ◽  
Sympathetic Nerves ◽  
Adrenergic Nerve ◽  
Sequence Of Events ◽  
Adrenergic Response ◽  
Adrenergic Nerve Terminals ◽  
Muscarinic Cholinergic ◽  
Related Compounds ◽  
Stimulation Of

Activation of muscarinic cholinergic receptors located at the terminal adrenergic nerve fiber inhibits the process of exocytotic norepinephrine (NE) release. This neuromodulatory effect of acetylcholine and related compounds has been discovered as a pharmacological phenomenon. Subsequently, evidence for a physiological role of the presynaptic muscarinic inhibition was obtained on organs known to be innervated by the autonomic ground plexus (Hillarp, Acta. Physiol. Scand. 46, Suppl. 157: 1-68, 1959) in which terminal adrenergic and cholinergic axons run side by side. Thus, in the heart electrical vagal stimulation inhibits the release of NE evoked by stimulation of sympathetic nerves, and this is reflected by a corresponding decrease in the postsynaptic adrenergic response. On the other hand, muscarinic antagonists such as atropine enhance the NE release evoked by field stimulation of tissues innervated by the autonomic ground plexus. The presynaptic muscarine receptor of adrenergic nerve terminals probably restricts the influx of calcium ions that triggers the release of NE. However, the sequence of events between recognition of the muscarinic compound by the receptor and the process of exocytosis still remains to be clarified.

The role of adenosine A1 receptors in the interaction between amygdala and entorhinal cortex of kindled rats

2005 ◽  
Vol 65 (1-2) ◽  
pp. 1-9 ◽  
Author(s):  
Mohammad Mohammad-Zadeh ◽  
Azam Amini ◽  
Javad Mirnajafi-Zadeh ◽  
Yaghoub Fathollahi
Keyword(s):  
Entorhinal Cortex ◽  
Adenosine A1 Receptors ◽  
Adenosine A1

The Role of Episodic Memories in Current and Future Well-Being

2011 ◽  
Vol 38 (4) ◽  
pp. 505-519 ◽  
Author(s):  
Frederick L. Philippe ◽  
Richard Koestner ◽  
Genevieve Beaulieu-Pelletier ◽  
Serge Lecours ◽  
Natasha Lekes
Keyword(s):  
Well Being ◽  
Episodic Memories

Protective Effect of Ifenprodil Against Spreading Depression in the Mouse Entorhinal Cortex

2004 ◽  
Vol 92 (4) ◽  
pp. 2610-2614 ◽  
Author(s):  
Leonardo Coutinho Faria ◽  
Istvan Mody
Keyword(s):  
Nmda Receptor ◽  
Entorhinal Cortex ◽  
Spreading Depression ◽  
Ion Homeostasis ◽  
Brain Slices ◽  
Nmda Receptor Antagonist ◽  
Cerebrovascular Diseases ◽  
Nr2b Receptor Subunit ◽  
Nr2b Receptor

In the brain, spreading depression (SD) is characterized by a large extracellular DC shift, a massive failure of ion homeostasis and a transient cessation of neuronal function. Clinically, SD is believed to be involved in various neurological disorders including migraine and cerebrovascular diseases. The propagation of cortical SD requires the release of glutamate, and N-methyl-d-aspartate (NMDA) receptors play a crucial role in this process. Here, we have isolated the NMDA receptor-mediated component of extracellularly recorded field excitatory postsynaptic potentials (fEPSPs) in layers 2–3 of the entorhinal cortex of murine brain slices. In the absence of GABAA and AMPA receptor-mediated synaptic transmission, stimulation of layer 6 afferents every 15–90 s elicited spontaneous SD on average within 18.5 min after the start of the stimulation. In the presence of ifenprodil, an NR2B receptor subunit-selective NMDA receptor antagonist, the occurrence of SD was nearly abolished. Our results are consistent with an important role of NR2B subunits in triggering SD in the entorhinal cortex.

Exhibition 58: Modern Architecture in England, Museum of Modern Art, 1937

2013 ◽  
Vol 56 ◽  
pp. 277-298 ◽  
Author(s):  
Alan Powers
Keyword(s):  
New York ◽  
Modern Art ◽  
Modern Architecture ◽  
Museum Of Modern Art ◽  
Multiple Sequence ◽  
Sequence Of Events ◽  
The World ◽  
The Usa ◽  
New Yorkers

Exhibition 58: Modern Architecture in England, held between 10 February and 7 March 1937 at the Museum of Modern Art in New York (MoMA), was a notable event. Amidst claims that ‘England leads the world in modern architectural activity’, the exhibition ‘amazed New Yorkers’ and equally surprised English commentators. However, it has not subsequently received any extended investigation. The present purpose is to look at it as a multiple sequence of events, involving other exhibitions, associated publications and the trajectories of individuals and institutions, through which tensions came to the surface about the definition and direction of Modernism in England and elsewhere. Such an analysis throws new light on issues such as the motives for staging the exhibition, the personnel involved and associated questions relating to the role of émigré architects in Britain and the USA, some of which have been misinterpreted in recent commentaries.Hitchcock's unequivocal claim for the importance of English Modernism at this point still arouses disbelief, and raises a question whether it can be accepted at face value or requires explaining in terms of some other hidden intention.

scholarly journals Memory: Looking back and looking forward

2018 ◽  
Vol 2 ◽  
pp. 239821281879483 ◽  
Author(s):  
John P. Aggleton ◽  
Richard G. M. Morris
Keyword(s):  
Neural Plasticity ◽  
Imaging Studies ◽  
Activation Patterns ◽  
Memory Research ◽  
Neuronal Ensembles ◽  
Disadvantaged Populations ◽  
Episodic Memories ◽  
Source Of Information ◽  
Looking Back

This review brings together past and present achievements in memory research, ranging from molecular to psychological discoveries. Despite some false starts, major advances include our growing understanding of learning-related neural plasticity and the characterisation of different classes of memory. One striking example is the ability to reactivate targeted neuronal ensembles so that an animal will seemingly re-experience a particular memory, with the further potential to modify such memories. Meanwhile, human functional imaging studies can distinguish individual episodic memories based on voxel activation patterns. While the hippocampus continues to provide a rich source of information, future progress requires broadening our research to involve other sites. Related challenges include the need to understand better the role of glial–neuron interactions and to look beyond the synapse as the sole site of experience-dependent plasticity. Unmet goals include translating our neuroscientific knowledge in order to optimise learning and memory, especially among disadvantaged populations.

Sign in / Sign up

Export Citation Format

Share Document