New theory of hippocampal function: Associated rehearsal of multiplexed coded symbols

Synapse ◽  
1989 ◽  
Vol 3 (3) ◽  
pp. 182-192 ◽  
Author(s):  
Bernard L. Strehler
Keyword(s):  
Hippocampal Function

scholarly journals Irrelevant background context decreases mnemonic discrimination and increases false memory

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mihály Racsmány ◽  
Dorottya Bencze ◽  
Péter Pajkossy ◽  
Ágnes Szőllősi ◽  
Miklós Marián
Keyword(s):  
Recognition Test ◽  
False Recognition ◽  
Pattern Separation ◽  
Hippocampal Function ◽  
Memory Research ◽  
Early Dementia ◽  
Similar Information ◽  
Behavioral Score ◽  
The Cost ◽  
Background Context

AbstractOne of the greatest commonplaces in memory research is that context improves recall and enhances or leaves recognition intact. Here we present results which draw attention to the fact that the reappearance of irrelevant and unattended background contexts of encoding significantly impairs memory discrimination functions. This manuscript presents the results of two experiments in which participants made indoor/outdoor judgements for a large number of object images presented together with individual, irrelevant and presumably unattended background scenes. On a subsequent unexpected recognition test participants saw the incidentally encoded target objects, visually similar lures or new foil objects on the same or new background scenes. Our results showed that although the reappearance of the background scene raised the hit rate for target objects, it decreased mnemonic discrimination, a behavioral score for pattern separation, a hippocampal function that is affected in early dementia. Furthermore, the presence of the encoded background scene at the recognition test increased the false recognition of lure objects, even when participants were explicitly instructed to neglect the context scene. Altogether these results gave evidence that if context increases recognition hits for target memories, it does so at the cost of increasing false recognition and diminished discriminability for similar information.

scholarly journals The DRD2 Taq1A polymorphism moderates the effect of PTSD symptom severity on the left hippocampal CA3 volume: a pilot study

2021 ◽  
Author(s):  
Minlan Yuan ◽  
Hongru Zhu ◽  
Yuchen Li ◽  
Fenfen Ge ◽  
Su Lui ◽  
...  
Keyword(s):  
Symptom Severity ◽  
Ptsd Symptom ◽  
Imaging System ◽  
Dopamine D2 Receptor ◽  
Magnetic Resonance Imaging System ◽  
Hippocampal Function ◽  
Hippocampal Ca3 ◽  
Ptsd Symptom Severity ◽  
Ptsd Symptomatology ◽  
Ptsd Severity

Abstract Rationale and objectives The hippocampus, especially the CA1, CA3, and dentate gyrus (DG) subfields, is reported to be associated with post-traumatic stress disorder (PTSD) after trauma. However, neuroimaging studies of the associations between PTSD and hippocampal subfield volumes have failed to yield consistent findings. The aim of this study is to examine whether the dopamine D2 receptor (DRD2) Taq1A polymorphism, which is associated with both hippocampal function and PTSD, moderated the association between PTSD severity and hippocampal CA1, CA3 and DG volumes. Methods T1-weighted images were acquired from 142 trauma survivors from the 2008 Wenchuan earthquake using a 3.0-T magnetic resonance imaging system. Hippocampal subfield segmentations were performed with FreeSurfer v6.0. We used the simple moderation model from the PROCESS v3.4 tool for SPSS 23.0 to examine the association between the rs1800497 polymorphism, PTSD severity, and hippocampal CA3 and DG volumes. Results A significant genotype × PTSD symptom severity interaction was found for the left CA3 volume (ΔF = 5.01, p = 0.008, ΔR2 = 0.05). Post hoc, exploratory analyses deconstructing the interaction revealed that severe PTSD symptomatology were associated with reduced left CA3 volume among TC heterozygotes (t =  − 2.86, p = 0.005). Conclusions This study suggests that DRD2 Taq1A polymorphism moderates the association between PTSD symptomatology and left CA3 volume, which promotes an etiological understanding of the hippocampal atrophy at the subfield level. This highlights the complex effect of environmental stress, and provides possible mechanism for the relationship between the dopaminergic system and hippocampal function in PTSD.

scholarly journals Changes in hippocampal function of ovariectomized rats after sequential low doses of estradiol to simulate the preovulatory estrogen surge

2007 ◽  
Vol 26 (9) ◽  
pp. 2595-2612 ◽  
Author(s):  
Helen E. Scharfman ◽  
Tana M. Hintz ◽  
Juan Gomez ◽  
Kerry A. Stormes ◽  
Sharon Barouk ◽  
...  
Keyword(s):  
Ovariectomized Rats ◽  
Low Doses ◽  
Hippocampal Function

Abstract P730: MCA Stroke Chronically Disrupts Hippocampal Activity and Cortico-Hippocampal Communication

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Zachary Ip ◽  
Gratianne Rabiller ◽  
Jiwei He ◽  
Shivalika Chavan ◽  
Yasuo Nishijima ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Memory Function ◽  
Brain Regions ◽  
Male Rats ◽  
Brain State ◽  
Signal Power ◽  
Hippocampal Function ◽  
Electrode Arrays ◽  
Mca Occlusion ◽  
Hippocampal Activity

Introduction: Cognition and memory deficits are common sequelae following middle cerebral artery (MCA) stroke, one of the most common strokes in humans. However MCA stroke does not compromise the structural integrity of the hippocampus, which is highly involved in memory function, because the MCA does not supply blood flow to the hippocampus. We previously reported on the acute effect of MCA stroke, where we observed increased hippocampal activity and cortico-hippocampal communication. Here we investigate chronic changes to local oscillations and cortico-hippocampal communication following MCA occlusion in rats two weeks and one month following stroke. Hypothesis: Cortical stroke affects remote brain regions, disrupting hippocampal function and cortico-hippocampal communication. Methods: We subjected male rats (n=28) to distal MCA occlusion compared to controls (n=19). We recorded local field potentials simultaneously from cortex and hippocampus two weeks and one month following stroke using 16-site linear electrode arrays under urethane anesthesia. We analyzed signal power, brain state, CFC, and sharp wave SPW-Rs to assess hippocampal function and cortico-hippocampal communication. Results: Our results show disruptions to local oscillations; lowered delta (1-3 Hz) signal power in the cortex and hippocampus, increased signal power in gamma (30-60 Hz) and high gamma (60-200 Hz) in cortex and hippocampus. Theta/delta brain state is disrupted, and SPW-Rs increase in power at two weeks, before returning to baseline levels at one month. Communication is also disrupted; Theta-gamma coupling, a measure of information being communicated between regions, breaks down after stroke. Conclusions: These results suggest that chronic stroke causes significant changes to hippocampal function, which can be characterized by these electrophysiological biomarkers, establishing putative targets for targeted stimulation therapies.

scholarly journals Early Loss of Vision Results in Extensive Reorganization of Plasticity-Related Receptors and Alterations in Hippocampal Function That Extend Through Adulthood

2018 ◽  
Vol 29 (2) ◽  
pp. 892-905 ◽  
Author(s):  
Mirko Feldmann ◽  
Daniela Beckmann ◽  
Ulf T Eysel ◽  
Denise Manahan-Vaughan
Keyword(s):  
Hippocampal Function ◽  
Loss Of Vision ◽  
Early Loss
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