Differences In Long-term Memory Research Articles

An examination of individual differences in levels of processing

ABSTRACT The present study examined individual differences in levels of processing. Participants completed a cued recall task in which they made either rhyme or semantic judgements on pairs of items. Pupillary responses during encoding were recorded as a measure of the allocation of attentional effort and participants completed multiple measures of working and long-term memory. The results suggested levels of processing effect in both accuracy and pupillary responses with deeper levels of processing demonstrating higher accuracy and larger pupillary responses than shallower levels of processing. Most participants demonstrated levels of processing effect, but there was substantial variability in the size of the effect. Variation in levels of processing was positively related to individual differences in long-term memory and the magnitude of the pupillary levels of processing effect, but not working memory. These results suggest that some of the variation in levels of processing is likely due to individual differences in the allocation of attentional effort (particularly to items processed deeply) during encoding.

Pupillary correlates of individual differences in long-term memory.

The present study is the first to examine individual differences in long-term memory, arousal dysregulation, and intensity of attention within the same experiment. Participants (N = 106) completed 28 lists of an immediate free-recall task while their pupil diameter was recorded via an eye-tracker during the encoding period. Two main pupillary measures were extracted: intraindividual variability in pre-list pupil diameter and evoked pupillary responses during item encoding. Variability in pre-list pupil diameter served as a measure of arousal dysregulation, and evoked pupillary responses served as a measure of intensity of attention. Based on prior work, we hypothesized that there would be a positive association between intensity of attention and recall ability, and that there would be a negative association between arousal dysregulation and recall ability. Collectively these two measures accounted for 19% of interindividual variance in recall, with 5% attributable uniquely to intensity of attention and 12% attributable uniquely to arousal regulation. The findings demonstrate that there are sources of individual differences in long-term memory that can be revealed via pupillometry, notably the amount of effort deployed during item encoding and the degree to which people exhibit dysregulated arousal. Both findings are consistent with recent theorizing regarding the role of the locus coeruleus (LC)-norepinephrine (NE) system's role in goal-directed cognition. Specifically, the LC governs both moment-to-moment arousal and NE release to cortical regions subserving cognitive processing. Among people for whom this system operates most optimally, long-term memory retention is superior.

Functional Connectivity during Encoding Predicts Individual Differences in Long-Term Memory.

What is the neural basis of individual differences in the ability to hold information in long-term memory (LTM)? Here, we first characterize two whole-brain functional connectivity networks based on fMRI data acquired during an n-back task that robustly predict individual differences in two important forms of LTM, recognition and recollection. We then focus on the recognition memory model and contrast it with a working memory model. Although functional connectivity during the n-back task also predicts working memory performance and the two networks have some shared components, they are also largely distinct from each other: The recognition memory model performance remains robust when we control for working memory, and vice versa. Functional connectivity only within regions traditionally associated with LTM formation, such as the medial temporal lobe and those that show univariate subsequent memory effect, have little predictive power for both forms of LTM. Interestingly, the interactions between these regions and other brain regions play a more substantial role in predicting recollection memory than recognition memory. These results demonstrate that individual differences in LTM are dependent on the configuration of a whole-brain functional network including but not limited to regions associated with LTM during encoding and that such a network is separable from what supports the retention of information in working memory.

Long-term memory of real-world episodes is independent of recency effects: magic tricks as ecological tasks

How episodic memories decay is an unresolved question in cognitive neuroscience. The role of short-term mechanisms regarding the decay of episodic memories is circumscribed to set the maximum recall from which a monotonic decay occurs. However, this sequential view from the short to the long-term is not compulsory, as short-term dependent memory gains (like recency effects when memorizing a list of elements; serial-position effects) may not be translated into long-term memory differences. Moreover, producing memorable events in the laboratory faces important challenges, such as recreating realistic conditions with elevated recall, or avoiding spontaneous retrievals during memory retention (sociocultural hooks). The current study proposes the use of magic to enhance the study of memory. We designed a sequence of magic tricks performed live on stage to evaluate the interaction between memory decay and serial-position effects of those tricks. The audience was asked to freely recall the tricks at four different timepoints: just after the show, 10 days, 1.5 months and 4.5 months. We discovered serial-position differences after the show that were no longer present later on, suggesting that short-term memory gains do not translate into the long-term. Illustrating the power of naturalistic stimuli to study long-term memory while interrogating the interaction between short-term and long-term mechanisms, this work is, to our knowledge, the first scientific study of the memorability of magic tricks.

Identifying the molecular systems that influence cognitive resilience to Alzheimer's disease in genetically diverse mice.

Individual differences in cognitive decline during normal aging and Alzheimer's disease (AD) are common, but the molecular mechanisms underlying these distinct outcomes are not fully understood. We utilized a combination of genetic, molecular, and behavioral data from a mouse population designed to model human variation in cognitive outcomes to search for the molecular mechanisms behind this population-wide variation. Specifically, we used a systems genetics approach to relate gene expression to cognitive outcomes during AD and normal aging. Statistical causal-inference Bayesian modeling was used to model systematic genetic perturbations matched with cognitive data that identified astrocyte and microglia molecular networks as drivers of cognitive resilience to AD. Using genetic mapping, we identified Fgf2 as a potential regulator of the astrocyte network associated with individual differences in short-term memory. We also identified several immune genes as regulators of a microglia network associated with individual differences in long-term memory, which was partly mediated by amyloid burden. Finally, significant overlap between mouse and two different human coexpression networks provided strong evidence of translational relevance for the genetically diverse AD-BXD panel as a model of late-onset AD. Together, this work identified two candidate molecular pathways enriched for microglia and astrocyte genes that serve as causal AD cognitive biomarkers, and provided a greater understanding of processes that modulate individual and population-wide differences in cognitive outcomes during AD.

Individual differences in long-term memory.

The literature on individual differences in long-term memory (LTM) is organized and reviewed. This includes an extensive review of the factor structure of LTM abilities as well as specific individual differences in criterial tasks such as free recall, paired associates recall, and recognition. It is demonstrated that individual differences in LTM abilities are represented by various lower order factors based on criterial tasks as well as by a more general higher-order LTM factor. These individual differences are linked with multiple different constructs including working memory, intelligence, and attention control. Individual differences in forgetting, interference control, false memory, testing effects, general retrieval abilities, and the influence of strategies are also examined. Overall, it is clear that there are substantial and robust individual differences in LTM abilities and that these abilities demonstrate important relations with other cognitive abilities. Future directions and an integration of individual differences in a general framework of memory are discussed, and it is suggested that combined experimental and correlational approaches are needed to better understand individual differences in LTM and that individual differences in LTM should be used to better test and revise theories of LTM processes. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Supplemental Material for Individual Differences in Long-Term Memory

Supplemental Material for Individual Differences in Long-Term Memory

Early postnatal nociceptive stimulation results in deficits of spatial memory in male rats

Prematurely-born infants are exposed to multiple invasive procedures while in the intensive care unit. Newborn rats and humans have similar behavioral responses to noxious stimulation. Previous studies have shown that early noxious stimuli may alter dentate gyrus neurogenesis and the behavioral repertoire of adult rats. We evaluated the late effects of noxious stimulation administered during different phases of development on two spatial memory tests; object recognition (OR) and Morris water maze (WM) tests. Noxious stimulation was induced by an intra-plantar injection of complete Freund’s adjuvant (CFA) on postnatal (P) day 1 (group P1) or 8 (P8). Control animals were not stimulated. Behavioral tests were conducted on P60 in both male and female animals. In the WM, three domains were evaluated: acquisition, probe trial performance and reversal re-acquisition. The number of Nissl stained cells in the dentate granule cell layer was assessed by stereological counting. The OR test revealed that P1 male rats had poor long-term memory compared to the control and P8 groups. In the WM, no short- or long-term memory differences were detected between early postnatal-stimulated male and female rats and their respective controls. However, the ability to find the hidden platform in a new position was reduced in P1 male rats. The number of dentate granule cells in P8 males was higher than in all other groups. This study demonstrates that noxious stimulation on P1 results in spatial learning deficits in male animals, but does not disrupt the development of the hippocampus-dependent strategies of learning and memory.

Learning-induced gene expression in the heads of two Nasonia species that differ in long-term memory formation.

BackgroundCellular processes underlying memory formation are evolutionary conserved, but natural variation in memory dynamics between animal species or populations is common. The genetic basis of this fascinating phenomenon is poorly understood. Closely related species of Nasonia parasitic wasps differ in long-term memory (LTM) formation: N. vitripennis will form transcription-dependent LTM after a single conditioning trial, whereas the closely-related species N. giraulti will not. Genes that were differentially expressed (DE) after conditioning in N. vitripennis, but not in N. giraulti, were identified as candidate genes that may regulate LTM formation.ResultsRNA was collected from heads of both species before and immediately, 4 or 24 hours after conditioning, with 3 replicates per time point. It was sequenced strand-specifically, which allows distinguishing sense from antisense transcripts and improves the quality of expression analyses. We determined conditioning-induced DE compared to naïve controls for both species. These expression patterns were then analysed with GO enrichment analyses for each species and time point, which demonstrated an enrichment of signalling-related genes immediately after conditioning in N. vitripennis only. Analyses of known LTM genes and genes with an opposing expression pattern between the two species revealed additional candidate genes for the difference in LTM formation. These include genes from various signalling cascades, including several members of the Ras and PI3 kinase signalling pathways, and glutamate receptors. Interestingly, several other known LTM genes were exclusively differentially expressed in N. giraulti, which may indicate an LTM-inhibitory mechanism. Among the DE transcripts were also antisense transcripts. Furthermore, antisense transcripts aligning to a number of known memory genes were detected, which may have a role in regulating these genes.ConclusionThis study is the first to describe and compare expression patterns of both protein-coding and antisense transcripts, at different time points after conditioning, of two closely related animal species that differ in LTM formation. Several candidate genes that may regulate differences in LTM have been identified. This transcriptome analysis is a valuable resource for future in-depth studies to elucidate the role of candidate genes and antisense transcription in natural variation in LTM formation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1355-1) contains supplementary material, which is available to authorized users.

Kinematic Strategies Underlying Improvement in the Acquisition of a Sequential Finger Task with Self-Generated vs. Cued Repetition Training

Many motor skills, such as typing, consist of articulating simple movements into novel sequences that are executed faster and smoother with practice. Dynamics of re-organization of these movement sequences with multi-session training and its dependence on the amount of self-regulation of pace during training is not yet fully understood. In this study, participants practiced a sequence of key presses. Training sessions consisted of either externally (Cued) or self-initiated (Uncued) training. Long-term improvements in performance speed were mainly due to reducing gaps between finger movements in both groups, but Uncued training induced higher gains. The underlying kinematic strategies producing these changes and the representation of the trained sequence differed significantly across subjects, although net gains in speed were similar. The differences in long-term memory due to the type of training and the variation in strategies between subjects, suggest that the different neural mechanisms may subserve the improvements observed in overall performance.

Reconstructing the Remote Television Memory Test: Measuring Individual Differences in Long-Term Memory

Memory plays a role in many communications theories; however, few studies consider individual differences in memory. The results are reported here for two original studies designed to reconstruct a previously validated measure for television memory constructed to assess how people forget information over time. The remote television memory test assesses recognition memory for the titles of broadcast television programs canceled after a single season. Results from two studies show that the measure is reliable across repeated administrations among independent samples, exhibits a forgetting curve over time, is uncorrelated with total television viewing, appears to be approximately normally distributed, and predicts social reality estimates typical of the cultivation effect independently from total viewing. More work is needed to further assess the construct validity of the measure. Practical implications of administration also are discussed.

Individual Differences in Emotional Memory: Adult Attachment and Long-Term Memory for Child Sexual Abuse

In the present study, attachment-related differences in long-term memory for a highly emotional life event, child sexual abuse (CSA), were investigated. Participants were 102 documented CSA victims whose cases were referred for prosecution approximately 14 years earlier. Consistent with the proposal that avoidant individuals defensively regulate the processing of potentially distressing information (Bowlby, 1980), attachment avoidance was negatively associated with memory for particularly severe CSA incidents. This finding was not mediated by the extent to which participants reported talking about the abuse after it occurred, although post abuse discussion did enhance long-term memory. In addition, accuracy was positively associated with maternal support following the abuse and extent of CSA-related legal involvement. Attachment anxiety was unrelated to memory accuracy, regardless of abuse severity. Implications of the findings for theories of avoidant defensive strategies and emotional memory are discussed.

Handedness and Cerebral Hemispheric Differences in Memory for Pictorial Organization

Handedness and cerebral hemispheric differences were investigated with regard to the way pictorial information is stored in long-term memory. Left- and right-handed men were required to remember a series of pictorial scenes that were organized or unorganized with respect to real-world configurations. Memory for these scenes was measured with half-field presentations of detail probes and whole-scene probes. There were no differences between the two visual fields in latency. An Organization x Probe interaction was found for accuracy scores for positive responses in the right visual field but not the left visual field. Furthermore, a three-way interaction (Organization x Probe x Visual Field) was significant among right-handers but not among left-handers. Findings are discussed in terms of hemispheric differences in long-term memory and hemispheric specialization referring to handedness.

Adult age differences in long-term memory for performed activities.

Participants in two studies conducted by Salthouse (in press) were called 2 to 182 days after participation and asked to describe the activities that they had performed in the previous study. Hierarchical regression analyses were used to examine the prediction of activity recall from age, speed, and retention interval. Overall, age was associated with 20% of the variance in activity recall, and retention interval was associated with 19%, but there was no significant interaction of age and retention interval. When perceptual speed was entered into the regression equation before age, the age-related variance was reduced by 70%. A small, but statistically significant, amount of age-related variance in activity memory remained after controlling for speed and retention interval.

Traumatic brain injury produces impairments in long-term and recent memory

Traumatic brain injury (TBI) in humans typically produces neurological suppression and a longer lasting impairment of memory clinically defined as post-traumatic amnesia. An animal model that reliably reproduces the physiological changes associated with TBI was used to assess the memory deficits following brain injury. Prior to TBI, rats were trained to perform one of four tasks that assessed either motor performance, long-term or recent memory. Rats were randomly assigned to one of three groups (anesthesia only, sham operation or fluid percussion). Following fluid percussion, used to produce TBI, rats were tested for 6 test sessions. The first session occurred 1–2 min after the experimental manipulation. The next 5 sessions followed the training schedule maintained prior to experimental manipulation. Differences in long-term memory occurred only in the first post-operative test session. Differences in recent memory performance were found across all 6 test sessions. The memory deficits were clearly dissociated from motor deficits. The similar memory deficits observed following human head injury and the experimentally produced TBI injury demonstrate that fluid percussion is a useful approach to examine underlying neurobiological mechanisms involved in head injury and possible clinical interventions.

The effects of selective inattention upon the electrodermal orienting reflex: A test of information-processing theory

Information-processing theories of the orienting reflex (OR) predict that disruptions of attention which impede the registration of a stimulus in memory should retard habituation of the OR. Studies examining effects of selective inattention upon rate of habituation of skin conductance responses (SCRs) to concurrently presented stimuli have yielded inconsistent results. We employed a dichotic vigilance task calling for selective attention to either male-voice or female-voice words. Comparisons between previously attended versus nonattended stimuli were subsequently conducted for habituation of SCR, as well as for a direct measure of recognition memory. Although there were unequivocal differences in long-term memory between attended and non-attended material, there was no clear evidence for corresponding differences in either initial magnitude or rate of habituation of SCR. These data, which replicated results from an earlier study, failed to demonstrate an effect of memory on the OR as predicted by information-processing theories.