scholarly journals Development and decline of the hippocampal long-axis specialization and differentiation during encoding and retrieval of episodic memories

2018 ◽  
Author(s):  
Espen Langnes ◽  
Didac Vidal-Piñeiro ◽  
Markus H. Sneve ◽  
Inge K. Amlien ◽  
Kristine B Walhovd ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Task Engagement ◽  
Childhood And Adolescence ◽  
Associative Memories ◽  
Hippocampal Function ◽  
Successful Completion ◽  
Related Activity ◽  
Younger Adults ◽  
Development And Aging ◽  
Episodic Memories

AbstractChange in hippocampal function is a major factor in lifespan development and decline of episodic memory. Evidence indicates a long-axis specialization where anterior hippocampus is more engaged during encoding and posterior during retrieval. We tested the lifespan trajectory of hippocampal long-axis episodic memory-related activity and functional connectivity (FC). 496 participants (6.8-80.8 years) were scanned with functional MRI while encoding and retrieving associative memories. We found clear evidence for a long-axis encoding-retrieval specialization. These long-axis effects declined linearly during development and aging, eventually vanishing in the older adults. This was mainly driven by age effects on retrieval. Retrieval was associated with gradually lower activity from childhood to adulthood, followed by positive age-relationships until 70 years. Interestingly, this pattern characterized task engagement regardless of memory success or failure. Children engaged posterior hippocampus more than anterior, while anterior hippocampus was more activated relative to posterior already in teenagers. Intra-hippocampal connectivity increased during task, and this increase declined with age. In sum, the results suggest that hippocampal long-axis differentiation and communication during episodic memory tasks develop rapidly during childhood and adolescence, are markedly different in older compared to younger adults, and are related to task engagement, not the successful completion of the task.

scholarly journals Development and Decline of the Hippocampal Long-Axis Specialization and Differentiation During Encoding and Retrieval of Episodic Memories

2018 ◽  
Vol 29 (8) ◽  
pp. 3398-3414 ◽  
Author(s):  
Espen Langnes ◽  
Didac Vidal-Piñeiro ◽  
Markus H Sneve ◽  
Inge K Amlien ◽  
Kristine B Walhovd ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Life Span ◽  
Task Engagement ◽  
Age Effects ◽  
Associative Memories ◽  
Related Activity ◽  
Younger Adults ◽  
Successful Retrieval ◽  
Development And Aging ◽  
Episodic Memories

Abstract Change in hippocampal function is a major factor in life span development and decline of episodic memory. Evidence indicates a long-axis specialization where anterior hippocampus is more engaged during encoding than during retrieval, and posterior more engaged during retrieval than during encoding. We tested the life span trajectory of hippocampal long-axis episodic memory-related activity and functional connectivity (FC) in 496 participants (6.8–80.8 years) encoding and retrieving associative memories. We found evidence for a long-axis encoding–retrieval specialization that declined linearly during development and aging, eventually vanishing in the older adults. This was mainly driven by age effects on retrieval, which was associated with gradually lower activity from childhood to adulthood, followed by positive age relationships until 70 years. This pattern of age effects characterized task engagement regardless of memory success or failure. Especially for retrieval, children engaged posterior hippocampus more than anterior, while anterior was relatively more activated already in teenagers. Significant intrahippocampal connectivity was found during task, which declined with age. The results suggest that hippocampal long-axis differentiation and communication during episodic memory tasks develop rapidly during childhood, are different in older compared with younger adults, and that the age effects are related to task engagement, not the successful retrieval of episodic memories specifically.

scholarly journals The development of spatiotemporal organization of episodic memory in children and its disruption in Williams Syndrome

2019 ◽  
Author(s):  
Marilina Mastrogiuseppe ◽  
Natasha Bertelsen ◽  
Maria Francesca Bedeschi ◽  
Sang Ah Lee
Keyword(s):  
Episodic Memory ◽  
Williams Syndrome ◽  
Developmental Process ◽  
Spatial Location ◽  
Space Time ◽  
Hippocampal Function ◽  
Spatiotemporal Organization ◽  
Location Memory ◽  
Space And Time ◽  
Episodic Memories

AbstractRecent theories of episodic memory propose that the hippocampus provides the spatiotemporal framework for episodic memories. If this is true, does the development of episodic memory depend on the binding of space and time? And does this rely, at least partly, on normal hippocampal function? We investigated the development of episodic memory in children 2–8 years of age (Study 1) and its impairment in Williams Syndrome (Study 2) by implementing a nonverbal object-placement task that dissociates the what, where, and when components of episodic memory. Our results indicate that the binding of space and time in memory emerges first in development around the age of 3 and is impaired in Williams Syndrome. Space-time binding both preceded and predicted success in full episodic memory (what+where+when), and associating objects to spatial location seemed to mediate this developmental process. Importantly, these effects were not explained by improvements in object or location memory.

scholarly journals Bi-Temporal Anodal Transcranial Direct Current Stimulation during Slow-Wave Sleep Boosts Slow-Wave Density but Not Memory Consolidation

2021 ◽  
Vol 11 (4) ◽  
pp. 410
Author(s):  
Simon Ruch ◽  
Kristoffer Fehér ◽  
Stephanie Homan ◽  
Yosuke Morishima ◽  
Sarah Maria Mueller ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Slow Wave ◽  
Direct Current ◽  
Memory Consolidation ◽  
Transcranial Direct Current Stimulation ◽  
Slow Wave Sleep ◽  
Memory Performance ◽  
Direct Current Stimulation ◽  
Sleep Parameters ◽  
Episodic Memories

Slow-wave sleep (SWS) has been shown to promote long-term consolidation of episodic memories in hippocampo–neocortical networks. Previous research has aimed to modulate cortical sleep slow-waves and spindles to facilitate episodic memory consolidation. Here, we instead aimed to modulate hippocampal activity during slow-wave sleep using transcranial direct current stimulation in 18 healthy humans. A pair-associate episodic memory task was used to evaluate sleep-dependent memory consolidation with face–occupation stimuli. Pre- and post-nap retrieval was assessed as a measure of memory performance. Anodal stimulation with 2 mA was applied bilaterally over the lateral temporal cortex, motivated by its particularly extensive connections to the hippocampus. The participants slept in a magnetic resonance (MR)-simulator during the recordings to test the feasibility for a future MR-study. We used a sham-controlled, double-blind, counterbalanced randomized, within-subject crossover design. We show that stimulation vs. sham significantly increased slow-wave density and the temporal coupling of fast spindles and slow-waves. While retention of episodic memories across sleep was not affected across the entire sample of participants, it was impaired in participants with below-average pre-sleep memory performance. Hence, bi-temporal anodal direct current stimulation applied during sleep enhanced sleep parameters that are typically involved in memory consolidation, but it failed to improve memory consolidation and even tended to impair consolidation in poor learners. These findings suggest that artificially enhancing memory-related sleep parameters to improve memory consolidation can actually backfire in those participants who are in most need of memory improvement.

scholarly journals Autobiographically Significant Concepts: More Episodic than Semantic in Nature? An Electrophysiological Investigation of Overlapping Types of Memory

2015 ◽  
Vol 27 (1) ◽  
pp. 57-72 ◽  
Author(s):  
Louis Renoult ◽  
Patrick S. R. Davidson ◽  
Erika Schmitz ◽  
Lillian Park ◽  
Kenneth Campbell ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Semantic Memory ◽  
Recognition Task ◽  
Positive Component ◽  
Late Positive Component ◽  
Episodic Information ◽  
Semantic Concepts ◽  
N400 Component ◽  
Episodic Memories ◽  
Highly Correlated

A common assertion is that semantic memory emerges from episodic memory, shedding the distinctive contexts associated with episodes over time and/or repeated instances. Some semantic concepts, however, may retain their episodic origins or acquire episodic information during life experiences. The current study examined this hypothesis by investigating the ERP correlates of autobiographically significant (AS) concepts, that is, semantic concepts that are associated with vivid episodic memories. We inferred the contribution of semantic and episodic memory to AS concepts using the amplitudes of the N400 and late positive component, respectively. We compared famous names that easily brought to mind episodic memories (high AS names) against equally famous names that did not bring such recollections to mind (low AS names) on a semantic task (fame judgment) and an episodic task (recognition memory). Compared with low AS names, high AS names were associated with increased amplitude of the late positive component in both tasks. Moreover, in the recognition task, this effect of AS was highly correlated with recognition confidence. In contrast, the N400 component did not differentiate the high versus low AS names but, instead, was related to the amount of general knowledge participants had regarding each name. These results suggest that semantic concepts high in AS, such as famous names, have an episodic component and are associated with similar brain processes to those that are engaged by episodic memory. Studying AS concepts may provide unique insights into how episodic and semantic memory interact.

scholarly journals Coding of episodic memory in the human hippocampus

2018 ◽  
Vol 115 (5) ◽  
pp. 1093-1098 ◽  
Author(s):  
John T. Wixted ◽  
Stephen D. Goldinger ◽  
Larry R. Squire ◽  
Joel R. Kuhn ◽  
Megan H. Papesh ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Single Neuron ◽  
Large Fraction ◽  
Memory Task ◽  
Neuron Activity ◽  
Distributed Coding ◽  
Repeated Word ◽  
Human Hippocampus ◽  
Left Hippocampus ◽  
Episodic Memories

Neurocomputational models have long posited that episodic memories in the human hippocampus are represented by sparse, stimulus-specific neural codes. A concomitant proposal is that when sparse-distributed neural assemblies become active, they suppress the activity of competing neurons (neural sharpening). We investigated episodic memory coding in the hippocampus and amygdala by measuring single-neuron responses from 20 epilepsy patients (12 female) undergoing intracranial monitoring while they completed a continuous recognition memory task. In the left hippocampus, the distribution of single-neuron activity indicated that only a small fraction of neurons exhibited strong responding to a given repeated word and that each repeated word elicited strong responding in a different small fraction of neurons. This finding reflects sparse distributed coding. The remaining large fraction of neurons exhibited a concurrent reduction in firing rates relative to novel words. The observed pattern accords with longstanding predictions that have previously received scant support from single-cell recordings from human hippocampus.

Effects of virtual reality-based spatial cognitive training on hippocampal function of older adults with mild cognitive impairment

2020 ◽  
pp. 1-7
Author(s):  
Jin-Hyuck Park
Keyword(s):  
Older Adults ◽  
Virtual Reality ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Episodic Memory ◽  
Spatial Cognition ◽  
Cognitive Training ◽  
Verbal Learning ◽  
Cognitive Intervention ◽  
Hippocampal Function

ABSTRACT Background: To date, there is a controversy on effects of cognitive intervention to maintain or improve hippocampal function for older adults with mild cognitive impairment (MCI). Objective: The main objective of this study was to exam effects of virtual reality-based spatial cognitive training (VR-SCT) using VR on hippocampal function of older adults with MCI. Method: Fifty-six older adults with MCI were randomly allocated to the experimental group (EG) that received the VR-SCT or the waitlist control group (CG) for a total of 24 sessions. To investigate effects of the VR-SCT on spatial cognition and episodic memory, the Weschsler Adult Intelligence Scale-Revised Block Design Test (WAIS-BDT) and the Seoul Verbal Learning Test (SVLT) were used. Results: During the sessions, the training performances gradually increased (p < .001). After the intervention, the EG showed significant greater improvements in the WAIS-BDT (p < .001, η2 = .667) and recall of the SVLT (p < .05, η2 =.094) compared to the CG but in recognition of the SVLT (p > .05, η2 =.001). Conclusion: These results suggest that the VR-SCT might be clinically beneficial to enhance spatial cognition and episodic memory of older adults with MCI.

scholarly journals Intrinsic motivation and episodic memories for robot exploration of high-dimensional sensory spaces

2020 ◽  
pp. 105971232092291
Author(s):  
Guido Schillaci ◽  
Antonio Pico Villalpando ◽  
Verena V Hafner ◽  
Peter Hanappe ◽  
David Colliaux ◽  
...  
Keyword(s):  
Neural Networks ◽  
Episodic Memory ◽  
Intrinsic Motivation ◽  
Computational Models ◽  
Deep Neural Networks ◽  
Image Sensor ◽  
Forward Kinematics ◽  
High Dimensional ◽  
Episodic Memories ◽  
Low Dimensional

This work presents an architecture that generates curiosity-driven goal-directed exploration behaviours for an image sensor of a microfarming robot. A combination of deep neural networks for offline unsupervised learning of low-dimensional features from images and of online learning of shallow neural networks representing the inverse and forward kinematics of the system have been used. The artificial curiosity system assigns interest values to a set of pre-defined goals and drives the exploration towards those that are expected to maximise the learning progress. We propose the integration of an episodic memory in intrinsic motivation systems to face catastrophic forgetting issues, typically experienced when performing online updates of artificial neural networks. Our results show that adopting an episodic memory system not only prevents the computational models from quickly forgetting knowledge that has been previously acquired but also provides new avenues for modulating the balance between plasticity and stability of the models.

scholarly journals Sensory–perceptual episodic memory and its context: autobiographical memory

2001 ◽  
Vol 356 (1413) ◽  
pp. 1375-1384 ◽  
Author(s):  
Martin A. Conway
Keyword(s):  
Episodic Memory ◽  
Life Span ◽  
Autobiographical Memory ◽  
Knowledge Base ◽  
Recent Experience ◽  
Perceptual Knowledge ◽  
Recollective Experience ◽  
Episodic Memories ◽  
Retention Intervals ◽  
Memory Knowledge

Episodic memory is reconceived as a memory system that retains highly detailed sensory perceptual knowledge of recent experience over retention intervals measured in minutes and hours. Episodic knowledge has yet to be integrated with the autobiographical memory knowledge base and so takes as its context or referent the immediate past of the experiencing self (or the ‘I’). When recalled it can be accessed independently of content and is recollectively experienced. Autobiographical memory, in contrast, retains knowledge over retention intervals measured in weeks, months, years, decades and across the life span. Autobiographical knowledge represents the experienced self (or the ‘me’), is always accessed by its content and, when accessed, does not necessarily give rise to recollective experience. Instead, recollective experience occurs when autobiographical knowledge retains access to associated episodic memories. In this reworking of the ‘episodic memory’ concept autobiographical memory provides the instantiating context for sensory–perceptual episodic memory.

Composition and replay of mnemonic sequences: The contributions of REM and slow-wave sleep to episodic memory

2013 ◽  
Vol 36 (6) ◽  
pp. 610-611 ◽  
Author(s):  
Sen Cheng ◽  
Markus Werning
Keyword(s):  
Episodic Memory ◽  
Eye Movement ◽  
Slow Wave ◽  
Rem Sleep ◽  
Neural Activity ◽  
Slow Wave Sleep ◽  
Place Cells ◽  
Object Representations ◽  
Episodic Memories ◽  
Gamma Band Oscillations

AbstractWe propose that rapid eye movement (REM) and slow-wave sleep contribute differently to the formation of episodic memories. REM sleep is important for building up invariant object representations that eventually recur to gamma-band oscillations in the neocortex. In contrast, slow-wave sleep is more directly involved in the consolidation of episodic memories through replay of sequential neural activity in hippocampal place cells.

Sign in / Sign up

Export Citation Format

Share Document