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"Memory retrieval"
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When we are no more : how digital memory is shaping our future
Examines how humanity records and passes on its culture to future generations, from the libraries of antiquity to the excess of information available in the digital age, and how ephemeral digital storage methods present a challenge for passing on current cultural memory to the future.
Book
AMPA Receptors: A Key Piece in the Puzzle of Memory Retrieval
Retrieval constitutes a highly regulated and dynamic phase in memory processing. Its rapid temporal scales require a coordinated molecular chain of events at the synaptic level that support transient memory trace reactivation. AMPA receptors (AMPAR) drive the majority of excitatory transmission in the brain and its dynamic features match the singular fast timescales of memory retrieval. Here we provide a review on AMPAR contribution to memory retrieval regarding its dynamic movements along the synaptic compartments, its changes in receptor number and subunit composition that take place in activity dependent processes associated with retrieval. We highlight on the differential regulations exerted by AMPAR subunits in plasticity processes and its impact on memory recall.
Journal Article
Altered Brain Activation During Memory Retrieval Precedes and Predicts Conversion to Psychosis in Individuals at Clinical High Risk
Memory deficits are a hallmark of psychotic disorders such as schizophrenia. However, whether the neural dysfunction underlying these deficits is present before the onset of illness and potentially predicts conversion to psychosis is unclear. In this study, we investigated brain functional alterations during memory processing in a sample of 155 individuals at clinical high risk (including 18 subjects who later converted to full psychosis) and 108 healthy controls drawn from the second phase of the North American Prodrome Longitudinal Study (NAPLS-2). All participants underwent functional magnetic resonance imaging with a paired-associate memory paradigm at the point of recruitment and were clinically followed up for approximately 2 years. We found that at baseline, subjects at high risk showed significantly higher activation during memory retrieval in the prefrontal, parietal, and bilateral temporal cortices (PFWE < .035). This effect was more pronounced in converters than nonconverters and was particularly manifested in unmedicated subjects (P < .001). The hyperactivation was significantly correlated with retrieval reaction time during scan in converters (P = .009) but not in nonconverters and controls, suggesting an exaggerated retrieval effort. These findings suggest that hyperactivation during memory retrieval may mark processes associated with conversion to psychosis, and such measures have potential as biomarkers for psychosis prediction.
Journal Article
The effect of involuntary positive memory retrieval on mood repair of non-clinically depressed people
Previous studies have demonstrated that voluntary positive memory retrieval commonly leads to mood repair in the non-depressed population but not in depressed people, while it has been suggested that involuntary positive memory retrieval can repair the mood of depressed people. However, the difference in the mood repair effect between voluntary and involuntary positive memory retrieval on depressed people remains unclear from an experimental perspective, and thus, we examined this difference in a laboratory setting. After inducing negative mood in non-clinical participants with high and low depressive tendency (n = 48), they were asked to conduct a voluntary memory retrieval task or sound location task inducing involuntary memory retrieval. In this retrieval phase, participants retrieved memories of positive pictures that had been encoded in the laboratory. The results demonstrated that involuntary positive memory retrieval caused a more positive change in the mood of people with high depressive tendency compared to voluntary retrieval. These results suggest that involuntary positive memory retrieval contributes to the repair of depression.
Journal Article
Optogenetics and its application in neural degeneration and regeneration
Neural degeneration and regeneration are important topics in neurological diseases. There are limited options for therapeutic interventions in neurological diseases that provide simultaneous spatial and temporal control of neurons. This drawback increases side effects due to non-specific targeting. Optogenetics is a technology that allows precise spatial and temporal control of cells. Therefore, this technique has high potential as a therapeutic strategy for neurological diseases. Even though the application of optogenetics in understanding brain functional organization and complex behaviour states have been elaborated, reviews of its therapeutic potential especially in neurodegeneration and regeneration are still limited. This short review presents representative work in optogenetics in disease models such as spinal cord injury, multiple sclerosis, epilepsy, Alzheimer＇s disease and Parkinson＇s disease. It is aimed to provide a broader perspective on optogenetic therapeutic potential in neurodegeneration and neural regeneration.
Journal Article
Temporal evolution of cortical ensembles promoting remote memory retrieval
Memories of fearful events can last a lifetime. The prelimbic (PL) cortex, a subregion of prefrontal cortex, plays a critical role in fear memory retrieval over time. Most studies have focused on acquisition, consolidation, and retrieval of recent memories, but much less is known about the neural mechanisms of remote memory. Using a new knock-in mouse for activity-dependent genetic labeling (TRAP2), we demonstrate that neuronal ensembles in the PL cortex are dynamic. PL neurons TRAPed during later memory retrievals are more likely to be reactivated and make larger behavioral contributions to remote memory retrieval compared to those TRAPed during learning or early memory retrieval. PL activity during learning is required to initiate this time-dependent reorganization in PL ensembles underlying memory retrieval. Finally, while neurons TRAPed during earlier and later retrievals have similar broad projections throughout the brain, PL neurons TRAPed later have a stronger functional recruitment of cortical targets.DeNardo et al. characterize TRAP2, which allows genetic access to neurons based on their activity, and use it to show that neuronal ensembles in prelimbic cortex for remote fear memory undergo dynamic changes during the first 14 days after learning.
Journal Article
The hippocampal sharp wave–ripple in memory retrieval for immediate use and consolidation
Various cognitive functions have long been known to require the hippocampus. Recently, progress has been made in identifying the hippocampal neural activity patterns that implement these functions. One such pattern is the sharp wave–ripple (SWR), an event associated with highly synchronous neural firing in the hippocampus and modulation of neural activity in distributed brain regions. Hippocampal spiking during SWRs can represent past or potential future experience, and SWR-related interventions can alter subsequent memory performance. These findings and others suggest that SWRs support both memory consolidation and memory retrieval for processes such as decision-making. In addition, studies have identified distinct types of SWR based on representational content, behavioural state and physiological features. These various findings regarding SWRs suggest that different SWR types correspond to different cognitive functions, such as retrieval and consolidation. Here, we introduce another possibility — that a single SWR may support more than one cognitive function. Taking into account classic psychological theories and recent molecular results that suggest that retrieval and consolidation share mechanisms, we propose that the SWR mediates the retrieval of stored representations that can be utilized immediately by downstream circuits in decision-making, planning, recollection and/or imagination while simultaneously initiating memory consolidation processes.
Journal Article
When trying to recall our past, all roads lead to Rome: More evidence for the multi-process retrieval theory of autobiographical memory
In this study, we tested elements of the multi-process retrieval account of autobiographical memory, retrieval multiplicity, and retrieval selectivity. The retrieval multiplicity states that multiple different retrieval strategies are used to recall autobiographical memories, while the retrieval selectivity states that such retrieval strategies will vary in accord with the cuing environment. We tested these hypotheses across two experiments with the retrieve-aloud procedure. In the retrieve-aloud procedure, participants were required to verbalize their thoughts while attempting to retrieve personal memories in response to phrase cues (e.g.,
listening to music
). Experiments
1
and
2
found support for the retrieval multiplicity by showing that participants used a variety of different retrieval processes (eight different processes in total), while Experiment
1
found support for the retrieval selectivity by showing that retrieval strategies varied across different cue types. The implications of the findings are discussed with respect to autobiographical memory, as well as semantic memory.
Journal Article
Subhypnotic doses of propofol impair spatial memory retrieval in rats
Abundant evidence indicates that propofol profoundly affects memory processes, although its specific effects on memory retrieval have not been clarified. A recent study has indicated that hippocampal glycogen synthase kinase-3β（GSK-3β） activity affects memory. Constitutively active GSK-3β is required for memory retrieval, and propofol has been shown to inhibit GSK-3β. Thus, the present study examined whether propofol affects memory retrieval, and, if so, whether that effect is mediated through altered GSK-3β activity. Adult Sprague-Dawley rats were trained on a Morris water maze task（eight acquisition trials in one session） and subjected under the influence of a subhypnotic dose of propofol to a 24-hour probe trial memory retrieval test. The results showed that rats receiving pretest propofol（25 mg/kg） spent significantly less time in the target quadrant but showed no change in locomotor activity compared with those in the control group. Memory retrieval was accompanied by reduced phosphorylation of the serine-9 residue of GSK-3β in the hippocampus, whereas phosphorylation of the tyrosine-216 residue was unaffected. However, propofol blocked this retrieval-associated serine-9 phosphorylation. These findings suggest that subhypnotic propofol administration impairs memory retrieval and that the amnestic effects of propofol may be mediated by attenuated GSK-3β signaling in the hippocampus.
Journal Article
Memory retrieval processes help explain the incumbency advantage
Voters prefer political candidates who are currently in office (incumbents) over new candidates (challengers). Using the premise of query theory (Johnson, Häubl ＆ Keinan, 2007), we clarify the underlying cognitive mechanisms by asking whether memory retrieval sequences affect political decision making. Consistent with predictions, Experiment 1 (N = 256) replicated the incumbency advantage and showed that participants tended to first query information about the incumbent. Experiment 2 (N = 427) showed that experimentally manipulating participants' query order altered the strength of the incumbency advantage. Experiment 3 (N = 713) replicated Experiment 1 and, in additional experimental conditions, showed that the effects of incumbency can be overridden by more valid cues, like the candidates' ideology. Participants queried information about ideologically similar candidates earlier and also preferred these ideologically similar candidates. This is initial evidence for a cognitive, memory-retrieval process underling the incumbency advantage and political decision making.
Journal Article