EPS mid-career prize 2018: Inference within episodic memory reflects pattern completion

Recollection of episodic memories is a process of reconstruction where coherent events are inferred from subsets of remembered associations. Here, we investigated the formation of multielement events from sequential presentation of overlapping pairs of elements (people, places, and objects/animals), interleaved with pairs from other events. Retrievals of paired associations from a fully observed event (e.g., AB, BC, AC) were statistically dependent, indicating a process of pattern completion, but retrievals from a partially observed event (e.g., AB, BC, CD) were not. However, inference for unseen “indirect” associations (i.e., AC, BD or AD) from a partially observed event showed strong dependency with each other and with linking direct associations from that event. In addition, inference of indirect associations correlated with the product of performance on the linking direct associations across events (e.g., AC with ABxBC) but not on the non-linking association (e.g., AC with CD). These results were seen across three experiments, with greater differences in dependency between indirect and direct associations when they were separately tested, but similar results following single and repeated presentations of the direct associations. The results could be accounted for by a simple auto-associative network model of hippocampal memory function. Our findings suggest that pattern completion supports recollection of fully observed multielement events and the inference of indirect associations in partly observed multielement events, mediated via the directly observed linking associations (although the direct associations themselves were retrieved independently). Together with previous work, our results suggest that associative inference plays a key role in reconstructive episodic memory and does so through hippocampal pattern completion.

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Impact of Comorbid Depression on Serial Position Effects in Alzheimer’s Disease

GeroPsych ◽

10.1024/1662-9647/a000115 ◽

2014 ◽

Vol 27 (4) ◽

pp. 161-169 ◽

Cited By ~ 1

Author(s):

Nienke A. Hofrichter ◽

Sandra Dick ◽

Thomas G. Riemer ◽

Carsten Schleussner ◽

Monique Goerke ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Serial Position ◽

Episodic Memory ◽

Memory Performance ◽

Memory Function ◽

Word List ◽

Position Effects ◽

Serial Position Effects ◽

List Memory

Hippocampal dysfunction and deficits in episodic memory have been reported for both Alzheimer’s disease (AD) and major depressive disorder (MDD). Primacy performance has been associated with hippocampus-dependent episodic memory, while recency may reflect working memory performance. In this study, serial position profiles were examined in a total of 73 patients with MDD, AD, both AD and MDD, and healthy controls (HC) by means of CERAD-NP word list memory. Primacy performance was most impaired in AD with comorbid MDD, followed by AD, MDD, and HC. Recency performance, on the other hand, was comparable across groups. These findings indicate that primacy in AD is impaired in the presence of comorbid MDD, suggesting additive performance decrements in this specific episodic memory function.

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

Brain Sciences ◽

10.3390/brainsci11040410 ◽

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.

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Socio-sexuality and episodic memory function in women: further evidence of an adaptive “mating mode”

Memory & Cognition ◽

10.3758/s13421-013-0301-1 ◽

2013 ◽

Vol 41 (6) ◽

pp. 850-861 ◽

Cited By ~ 11

Author(s):

David S. Smith ◽

Benedict C. Jones ◽

Kevin Allan

Keyword(s):

Episodic Memory ◽

Memory Function

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The effects of acute exercise on episodic memory function among young university students: moderation considerations by biological sex

Health Promotion Perspectives ◽

10.15171/hpp.2019.14 ◽

2019 ◽

Vol 9 (2) ◽

pp. 99-104 ◽

Cited By ~ 6

Author(s):

Lauren Johnson ◽

Paul D. Loprinzi

Keyword(s):

Episodic Memory ◽

University Students ◽

Verbal Memory ◽

Acute Exercise ◽

Memory Function ◽

Verbal Learning ◽

Memory Task ◽

Moderate Intensity ◽

Term Memory ◽

Main Effect

Background: The objective of this study was to evaluate potential sex-specific differences on episodic memory function and determine whether sex moderates the effects of acute exercise on episodic memory.Methods: A randomized controlled intervention was employed. This experiment was conducted among young University students (mean age = 21 years). Both males (n=20) and females (n=20)completed two counterbalanced laboratory visits, with one visit involving a 15-minute bout of moderate-intensity exercise prior to the memory task. The control visit engaged in a time matched seated task. Memory function (including short-term memory, learning, and long-term memory) was assessed from the RAVLT (Rey Auditory Verbal Learning Test).Results: We observed a significant main effect for time (P<0.001, ƞ2p= 0.77) and a marginally significant main effect for sex (P=0.06, ƞ2p= 0.09), but no time by sex by condition interaction(P=0.91, ƞ2p= 0.01). We also observed some suggestive evidence of a more beneficial effect of acute exercise on memory for females. Conclusion: In conclusion, females outperformed males in verbal memory function. Additional research is needed to further evaluate whether sex moderates the effects of acute exercise on memory function.

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Hypothesized mechanisms through which acute exercise influences episodic memory

Physiology International ◽

10.1556/2060.105.2018.4.28 ◽

2018 ◽

Vol 105 (4) ◽

pp. 285-297 ◽

Cited By ~ 29

Author(s):

PD Loprinzi ◽

P Ponce ◽

E Frith

Keyword(s):

Growth Factor ◽

Episodic Memory ◽

Cerebral Circulation ◽

Acute Exercise ◽

Memory Function ◽

Cognitive Outcomes ◽

Chronic Exercise ◽

Growth Factor Production ◽

Underlying Mechanisms ◽

Exercise Induced

Emerging research demonstrates that exercise is favorably associated with several cognitive outcomes, including episodic memory function. The majority of the mechanistic work describing the underlying mechanisms of this effect has focused on chronic exercise engagement. Such mechanisms include, e.g., chronic exercise-induced neurogenesis, gliogenesis, angiogenesis, cerebral circulation, and growth factor production. Less research has examined the mechanisms through which acute (vs. chronic) exercise subserves episodic memory function. The purpose of this review is to discuss these potential underlying mechanisms, which include, e.g., acute exercise-induced (via several pathways, such as vagus nerve and muscle spindle stimulation) alterations in neurotransmitters, synaptic tagging/capturing, associativity, and psychological attention.

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Impact of secondhand smoke exposure on cognitive function among middle-aged and older women in China: findings from three waves of the China Health and Retirement Longitudinal Study

BMJ Open ◽

10.1136/bmjopen-2020-039824 ◽

2020 ◽

Vol 10 (11) ◽

pp. e039824

Author(s):

Anying Bai ◽

Yinzi Jin ◽

Yangmu Huang

Keyword(s):

Longitudinal Study ◽

Cognitive Function ◽

Episodic Memory ◽

Secondhand Smoke ◽

Chinese Women ◽

Memory Function ◽

Pooled Analysis ◽

Visuospatial Ability ◽

Global Cognitive Function ◽

Normal Cognitive Function

ObjectivesTo examine the association between secondhand smoke (SSH) and women’s global cognitive function and cognitive subdomains.DesignCohort study.ParticipantsData for this study were obtained from the China Health and Retirement Longitudinal Study (2011-2013-2015), and pooled analysis was applied to wave 1 and wave 2 (2011–2013), wave 2 and wave 3 (2013–2015) and wave 1 and wave 3 (2011–2015). Data from a total of 6875 Chinese women with normal cognitive function at baseline were selected for analysis, including 2981 who were interviewed in 2011, 2471 in 2013, and 1894 in 2015.Main outcome measures and methodsSHS was classified based on the number of exposed years (<25 years, ≥25 years to <30 years, ≥30 years to <40 years, ≥40 years). Global cognitive function, visuospatial ability, orientation and attention, and episodic memory function were used as measures of cognitive function. Three waves of data were pooled using a dummy variable to differentiate between 2-year and 4-year groups. LDV models were used to examine independent associations between SHS and cognitive function. Demographic factors, socioeconomic factors, baseline cognitive functioning and health conditions were controlled for in our models.ResultsSSH was found to be inversely and significantly associated with cognitive function. Compared with those who had not been exposed to household SSH, women who had lived with a smoking husband had a significantly faster cognition decline, especially in global cognitive function (β=−0.33, 95% CI=−0.66 to −0.01, p<0.01), visuospatial ability (β=−0.04, 95% CI=−0.08 to −0.01, p<0.05) and episodic memory function (β=−0.16, 95% CI=−0.31 to −0.01, p=0.031).ConclusionsHousehold SSH exposure for more than 40 years was associated with a more significant decline in global cognitive function, visuospatial ability and episodic memory function, but not in orientation and attention function among older Chinese women.

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

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00689 ◽

2015 ◽

Vol 27 (1) ◽

pp. 57-72 ◽

Cited By ~ 17

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.

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Coding of episodic memory in the human hippocampus

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1716443115 ◽

2018 ◽

Vol 115 (5) ◽

pp. 1093-1098 ◽

Cited By ~ 9

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.

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

Adaptive Behavior ◽

10.1177/1059712320922916 ◽

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.

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