scholarly journals Associative Memory Storage and Retrieval: Involvement of Theta Oscillations in Hippocampal Information Processing

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Federico Stella ◽  
Alessandro Treves
Keyword(s):  
Information Processing ◽  
Associative Memory ◽  
Memory Retrieval ◽  
Critical Role ◽  
Neuronal Firing ◽  
Memory Storage ◽  
Theta Oscillations ◽  
Hippocampal Region ◽  
Storage And Retrieval ◽  
Current Flows

Theta oscillations are thought to play a critical role in neuronal information processing, especially in the hippocampal region, where their presence is particularly salient. A detailed description of theta dynamics in this region has revealed not only a consortium of layer-specific theta dipoles, but also within-layer differences in the expression of theta. This complex and articulated arrangement of current flows is reflected in the way neuronal firing is modulated in time. Several models have proposed that these different theta modulators flexibly coordinate hippocampal regions, to support associative memory formation and retrieval. Here, we summarily review different approaches related to this issue and we describe a mechanism, based on experimental and simulation results, for memory retrieval in CA3 involving theta modulation.

scholarly journals Alpha/beta power decreases track the fidelity of stimulus-specific information

2019 ◽  
Author(s):  
Benjamin J. Griffiths ◽  
Stephen D. Mayhew ◽  
Karen J. Mullinger ◽  
João Jorge ◽  
Ian Charest ◽  
...  
Keyword(s):  
Information Processing ◽  
Memory Retrieval ◽  
Negative Relationship ◽  
Memory Task ◽  
Significant Negative Correlation ◽  
Neuronal Firing ◽  
Specific Information ◽  
Beta Power ◽  
Alpha Beta ◽  
Task Irrelevant

AbstractMassed synchronised neuronal firing is detrimental to information processing. When networks of task-irrelevant neurons fire in unison, they mask the signal generated by task-critical neurons. On a macroscopic level, mass synchronisation of these neurons can contribute to the ubiquitous alpha/beta (8-30Hz) oscillations. Reductions in the amplitude of these oscillations, therefore, may reflect a boost in the processing of high-fidelity information within the cortex. Here, we test this hypothesis. Twenty-one participants completed an associative memory task while undergoing simultaneous EEG-fMRI recordings. Using representational similarity analysis, we quantified the amount of stimulus-specific information represented within the BOLD signal on every trial. When correlating this metric with concurrently-recorded alpha/beta power, we found a significant negative correlation which indicated that as alpha/beta power decreased, our metric of stimulus-specific information increased. This effect generalised across cognitive tasks, as the negative relationship could be observed during visual perception and episodic memory retrieval. Further analysis revealed that this effect could be better explained by alpha/beta power decreases providing favourable conditions for information processing, rather than directly representing stimulus-specific information. Together, these results indicate that alpha/beta power decreases parametrically track the fidelity of both externally-presented and internally-generated stimulus-specific information represented within the cortex.

A hippocampal indexing model of memory retrieval based on state trajectory reconstruction

2013 ◽  
Vol 36 (6) ◽  
pp. 615-616
Author(s):  
Peter Ford Dominey
Keyword(s):  
Memory Retrieval ◽  
Cortical Activity ◽  
Memory Storage ◽  
Trajectory Reconstruction ◽  
Storage And Retrieval ◽  
State Trajectory ◽  
Indexing Model ◽  
Sequence Memory

AbstractA method is proposed where static patterns or snapshots of cortical activity that could be stored as hyperassociative indices in hippocampus can subsequently be retrieved and reinjected into the neocortex in order to enable neocortex to then proceed to unfold the corresponding sequence, thus implementing an index-based sequence memory storage and retrieval capability.

The role of vocalization, memory retrieval, and external symbols in cognitive evolution

1996 ◽  
Vol 19 (1) ◽  
pp. 159-164 ◽  
Author(s):  
Merlin Donald
Keyword(s):  
Memory Retrieval ◽  
High Speed ◽  
Integrated System ◽  
Memory Storage ◽  
Cognitive Evolution ◽  
Storage And Retrieval ◽  
Human Thought ◽  
Vocal Apparatus

AbstractThe human vocal apparatus is part of a vertically integrated system, and I agree with Licbennan that modern high-speed phonology co-evolved with our capacity for grammar. Olson and I agree that some distinctly human thought skills appear to be fairly recent cultural acquisitions related to the introduction of new symbolic technologies and external (that is, nonbiological) memory storage. Stenning's concern with my use of the term “episodic” can be resolved by distinguishing between episodic storage and retrieval. Baum's suggestions regarding courtship and cognitive evolution seem to apply better to mimetic expression than to language.

scholarly journals Allopregnanolone mediates affective switching through modulation of oscillatory states in the basolateral amygdala

2021 ◽  
Author(s):  
Pantelis Antonoudiou ◽  
Phillip LW Colmers ◽  
Najah L Walton ◽  
Grant L Weiss ◽  
Anne C Smith ◽  
...  
Keyword(s):  
Basolateral Amygdala ◽  
Post Partum ◽  
Critical Role ◽  
Behavioral Outcomes ◽  
Theta Oscillations ◽  
Allosteric Modulators ◽  
Post Partum Depression ◽  
Antidepressant Effects ◽  
Behavioral States ◽  
Network States

AbstractBrexanolone (allopregnanolone), was recently approved by the FDA for the treatment of post-partum depression, demonstrating long-lasting antidepressant effects. Despite our understanding of the mechanism of action of neurosteroids as positive allosteric modulators (PAMs) of GABAa receptors, we still do not fully understand how allopregnanolone exerts these persistent antidepressant effects. Here, we demonstrate that allopregnanolone and similar synthetic neuroactive steroid analogs, SGE-516 (tool-compound) and zuranolone (SAGE-217, investigational-compound), are capable of modulating oscillatory states across species, which we propose may contribute to long-lasting changes in behavioral states. We identified a critical role for interneurons in generating oscillations in the basolateral amygdala (BLA) and a role for delta-containing GABAaRs in mediating the ability of neurosteroids to modulate network and behavioral states. Actions of allopregnanolone in the BLA is sufficient to alter behavioral states and enhance BLA high-theta oscillations (6-12Hz) through delta-containing GABAa receptors, a mechanism distinct from other GABAa PAMs, such as benzodiazepines. Moreover, treatment with the allopregnanolone analog SGE-516 induces long-lasting protection from chronic stress-induced disruption of network states, which correlates with improved behavioral outcomes. Our findings demonstrate a novel molecular and cellular mechanism mediating the well-established anxiolytic and antidepressant effects of neuroactive steroids.

scholarly journals Concurrent feature-specific reactivation within the hippocampus and neocortex facilitates episodic memory retrieval

2021 ◽  
Author(s):  
Michael B. Bone ◽  
Bradley R. Buchsbaum
Keyword(s):  
Visual Cortex ◽  
Memory Retrieval ◽  
Visual Memory ◽  
Recognition Accuracy ◽  
Memory Task ◽  
Large Individual ◽  
Storage And Retrieval ◽  
Specific Index ◽  
Early Visual Cortex ◽  
Episodic Memories

AbstractThe hippocampus is a key brain region for the storage and retrieval of episodic memories, but how it performs this function is unresolved. According to the hippocampal indexing theory, the hippocampus stores an event-specific index of the pattern of neocortical activity that occurred during perception. During retrieval, reactivation of the index by a partial cue facilitates the reactivation of the associated neocortical pattern. Therefore, event-specific retrieval requires joint reactivation of the hippocampal index and the associated neocortical networks. To test this theory, we examine the relation between performance on a recognition memory task requiring retrieval of image-specific visual details and feature-specific reactivation within the hippocampus and neocortex. We show that trial-by-trial recognition accuracy correlates with neural reactivation of low-level features (e.g. luminosity and edges) within the posterior hippocampus and early visual cortex for participants with high recognition lure accuracy. As predicted, the two regions interact, such that recognition accuracy correlates with hippocampal reactivation only when reactivation co-occurs within the early visual cortex (and vice-versa). In addition to supporting the hippocampal indexing theory, our findings show large individual differences in the features underlying visual memory and suggest that the anterior and posterior hippocampus represents gist-like and detailed features, respectively.

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