A dual mechanisms of control account of age differences in working memory.

Age-related differences in working memory (WM) can be large, but the exact sources are unclear. We hypothesized that young adults outperform older adults on WM tasks because they use controlled attention processes to prioritize the maintenance of relevant information in WM in a proactive mode, whereas older adults tend to rely on the strength of familiarity signals to make memory decisions in a reactive mode. We used a WM task that cued participants to prioritize one item over others and presented repeated lure probes that cause errors when one is engaged in a reactive mode. Results showed that, relative to young adults with full attention available to use proactive control during the delays, older adults with full attention (and young adults with divided attention) during the delays had exaggerated error rates to repeated lure probes compared to control probes. When the amount of proactive interference was increased (by repeating stimuli across trials), older adults were able to engage in proactive control, and this eliminated their exaggerated error rate (while young adults with divided attention could not). These results provide evidence for a dual mechanisms of control account of age differences in WM. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Naturalistic assessments in virtual reality and in real life help resolve the age-prospective memory paradox.

Cognitive aging researchers have long reported "paradoxical" age differences in prospective memory (PM), with age deficits in laboratory settings and age benefits (or no deficits) in real-world settings. We propose a theoretical account that explains this "age-PM-paradox" as a consequence of both methodological factors and developmental changes in cognitive abilities and personality traits. To test this account, young and older adults performed a series of naturalistic PM tasks in the lab and real world. Age-related PM deficits were observed in both lab-based tasks where demands were implemented using virtual reality and in-person role-playing. In contrast, older adults performed equal to or better than young adults on both real-world tasks, where demands were implemented in participants' daily lives. Consistent with our proposed account, an index of these "paradoxical" effects was partially predicted by age-related differences in working memory, vigilance, agreeableness, and neuroticism, whose predictive utility varied across task settings.

Are latent working memory items retrieved from long-term memory?

Switching one's focus of attention between to-be-remembered items in working memory (WM) is critical for cognition, but the mechanisms by which this is accomplished are unclear. A long-term memory (LTM) account suggests that switching attention away from an item, and passively retaining and reactivating such "latent" items back into the focus of attention involves episodic LTM retrieval processes, even for delays of only a few seconds. We tested this hypothesis using a two-item, double-retrocue WM task that requires participants to switch attention away from and reactivate items followed by subsequent LTM tests for reactivated items from the initial WM task (vs. continuously retained or untested control items). We compared performance on these tests between older adults (a population with LTM deficits) and young adults with either full (Experiment 1) or divided (Experiment 2) attention during the WM delay periods. The effects of reactivating latent items, as well as ageing and divided attention, had significant effects on WM performance, but did not interact with or systematically affect subsequent LTM for reactivated versus control items on item-, location-, or associative-recognition memory judgements made with either high or low confidence. Experiment 3 confirmed that these effects did not depend on whether or not young participants were warned about the subsequent LTM tests before performing the WM task. These dissociations between WM and LTM are inconsistent with the LTM account of latent WM; they are more consistent with the dynamic processing model of WM (Current Directions in Psychological Science).

Are irrelevant items actively deleted from visual working memory?: No evidence from repulsion and attraction effects in dual-retrocue tasks.

Some theories propose that working memory (WM) involves the active deletion of irrelevant information, including items that were retained in WM, but are no longer relevant for ongoing cognition. Considerable evidence suggests that active-deletion occurs for categorical representations, but whether it also occurs for recall of features that are typically bound together in an object, such as line orientations, is unclear. In two experiments, with or without binding instructions, healthy young adults maintained two orientations, focused attention to recall the orientation cued first, and then switched attention to recall the orientation cued second, at which point the uncued orientation was no longer relevant on the trial. In contrast to the active-deletion hypothesis, the results showed that the no-longer-relevant items exerted the strongest bias on participants' recall, which was either repulsive or attractive depending on both the degree of difference between the target and nontarget orientations and the proximity to cardinal axes. We suggest that visual WM can bind features like line orientations into chunked representations, and an irrelevant feature of a chunked object cannot be actively deleted - it biases recall of the target feature. Models of WM need to be updated to explain this and related dynamic phenomena.

Hippocampal involvement in working memory following refreshing.

Working memory (WM) and long-term memory (LTM) tests have both overlapping and distinct neurocognitive processes. Hippocampal activity in fMRI studies-a hallmark of LTM-also occurs on WM tasks, typically during encoding or retrieval and sometimes (albeit rarely) through 'late-delay' periods. The Synaptic Theory of WM suggests that 'activity-silent' synaptic weights retain temporary, WM-relevant codes without sustained, elevated activity. The hippocampus temporarily retains item-context bindings during WM-delays that are typically 'silent' to fMRI, probably via oscillatory patterns of informational connectivity among task-relevant regions of cortex. Advancing WM theory will require modeling this dynamic interplay, as in the 'Dynamic Processing Model of WM.

Medial prefrontal cortex has a causal role in selectively enhanced consolidation of emotional memories after a 24-hour delay: A TBS study.

Previous research points to an association between retrieval-related activity in the medial prefrontal cortex (mPFC) and preservation of emotional information compared to co-occurring neutral information following sleep. Although the role of the mPFC in emotional memory likely begins at encoding, little research has examined how mPFC activity during encoding interacts with consolidation processes to enhance emotional memory. This issue was addressed in the present study using transcranial magnetic stimulation in conjunction with an emotional memory paradigm. Healthy young adults encoded negative and neutral scenes while undergoing concurrent TMS with a modified short intermittent theta burst stimulation (sTBS) protocol. Participants received stimulation to either the mPFC or an active control site (motor cortex) during the encoding phase. Recognition memory for scene components (objects and backgrounds) was assessed after a short (30-minute) and a long delay (24-hour, including a night of sleep) to obtain measures of specific and gist-based memory processes. The results demonstrated that, relative to control stimulation, sTBS to the mPFC enhanced memory for negative objects on the long delay test (collapsed across specific and gist-based memory measures). mPFC stimulation had no discernable effect on memory for objects on the short delay test nor on the background images at either test. These results suggest that mPFC activity occurring during encoding interacts with consolidation processes to preferentially preserve negatively salient information.SIGNIFICANCE STATEMENT:Understanding how emotional information is remembered over time is critical to understanding memory in the real world. The present study used noninvasive brain stimulation (repetitive transcranial magnetic stimulation, rTMS) to investigate the interplay between mPFC activity that occurs during memory encoding and its subsequent interactions with consolidation processes. rTMS delivered to the mPFC during encoding enhanced memory for negatively valenced pictures on a test following a 24-hr delay, with no such effect on a test occurring shortly after the encoding phase. These results are consistent with the hypothesis that emotional aspects of memories are differentially subjected to consolidation processes, and that the mPFC might contribute to this "tag-and-capture" mechanism during the initial formation of such memories.

Acting with the future in mind: Testing competing prospective memory interventions.

Prospective memory (PM) is a critical determinant of whether a person is able to lead an independent life. Because PM declines in late adulthood, an important question is therefore whether, and if so, which types, of PM interventions might lead to meaningful benefits. In the present study, we randomly assigned older adults to one of four conditions, in three of which participants received a structured PM intervention (Restorative, Compensatory, and Combined Restorative and Compensatory); the fourth was an Active Control condition. The results showed that there were significant gains on the PM training task used for both the Restorative and Combined conditions. We then analyzed change in PM tasks that were independent of the PM training task (Near Transfer). Only the Combined condition led to post-training improvement. Finally, we analyzed performance on measures of untrained cognitive abilities and everyday functioning: Far transfer effects were not evident for any intervention. These data align with prior literature in showing that interventions that target a single cognitive ability do not reliably generate far transfer effects, and additionally extend our understanding of these effects in two important ways. Firstly, they indicate that, even when the memory challenges that older adults are most concerned about are the direct target of restorative training, transfer effects to untrained cognitive domains may be difficult to achieve. Secondly, they indicate that for older adults whose primary goal is to enhance PM function, combining Restorative and Compensatory approaches is an effective approach. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Attention Biases Competition for Visual Representation via Dissociable Influences from Frontal and Parietal Cortex.

What mechanisms underlie the prioritization of neural representations of visually perceived information to guide behavior? We assessed the dynamics whereby attention biases competition for representation of visual stimuli by enhancing representations of relevant information and suppressing the irrelevant. Multivariate pattern analysis (MVPA) classifiers were trained to discriminate patterns of fMRI activity associated with each of three stimuli, within several predefined ROIs. Participants performed a change-detection task wherein two of three presented items flashed at 1 Hz, one to each side of central fixation. Both flashing stimuli would unpredictably change state, but participants covertly counted the number of changes only for the cued item. In the ventral occipito-temporal ROI, MVPA evidence (a proxy for representational fidelity) was dynamically enhanced for attended stimuli and suppressed for unattended stimuli, consistent with a mechanism of biased competition between stimulus representations. Frontal and parietal ROIs displayed a qualitatively distinct, more "source-like" profile, wherein MVPA evidence for only the attended stimulus could be observed above baseline levels. To assess how attentional modulation of ventral occipito-temporal representations might relate to signals originating in the frontal and/or parietal ROIs, we analyzed informational connectivity (IC), which indexes time-varying covariation between regional levels of MVPA evidence. Parietal-posterior IC was elevated during the task, but did not differ for cued versus uncued items. Frontal-posterior IC, in contrast, was sensitive to an item's priority status. Thus, although regions of frontal and parietal cortex act as sources of top-down attentional control, their precise functions likely differ.

Implementation intentions and prospective memory function in late adulthood.

Prospective memory (PM) is a critically important component of memory that often declines in late adulthood. Implementation intentions, an encoding strategy, consisting of an explicit if-then "I will . . ." statement, has been effectively used to enhance older adults' prospective memory function. However, it remains to be established whether forming a mental representation of carrying out the task when forming the intention enhances these age effects, as well as whether the type of cue (event or time based) moderates age-related benefits. To test these questions, we randomly allocated 125 younger and 125 older adults to 1 of 5 conditions, in which they were directed to use different strategies when forming their PM intentions (Statement Only, Imagine in Game, Statement and Imagine Combined, Imagine in Daily Life, Control). The results indicated that use of the implementation intentions statement alone and in combination with forming a mental representation of carrying out the task substantially enhanced older adults' event- but not time-based PM. In addition, while the Statement Only condition reduced age-related difficulties for event-based tasks, the condition that combined this statement with visualization led to the greatest reduction in age effects. These data suggest that both rehearsing the implementations intention in the specific statement format combined with visualizing may be optimally effective for enhancing PM function in late adulthood but that the type of PM cue is an important moderator of these age effects. In addition to theoretical implications, these results may inform the refinement of interventions focused on enhancing PM function in late adulthood. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Differences in time-based task characteristics help to explain the age-prospective memory paradox.

Prior prospective memory (PM) research shows paradoxical findings-young adults outperform older adults in laboratory settings, but the reverse is found in naturalistic settings. Moreover, young-old outperform old-old adults in laboratory settings, but show no age differences in naturalistic settings. Here we highlight how time-based task characteristics have differed systematically between studies conducted in laboratory (time-interval cues) and naturalistic settings (time-of-day cues) and argue that this apparent paradox is a function of comparing disparate task types. In three experiments, we tested this hypothesis using analogous paradigms across settings, with event-based, time-of-day, and time-interval cued PM tasks. Experiment 1 compared young (n = 40) and older (n = 53) adults on a laboratory paradigm that measured PM tasks embedded in a virtual, daily life narrative; and on a conceptually parallel paradigm using a customized smartphone application (MEMO) in actual daily life. Results revealed that on the MEMO, older adults outperformed young adults on the time-of-day tasks but did not differ on the time-interval or event-based task. In contrast, older adults performed worse than young adults in the laboratory. Experiment 2 compared PM performance in young-old (n = 64) and old-old (n = 40) adults using the same paradigms. Young-old outperformed old-old adults in the laboratory; however, group differences were not evident in daily life. Experiment 3 compared young (n = 42) and older (n = 41) adults, and largely replicated the findings of Experiment 1 using a more demanding version of MEMO. These findings provide novel and important insights into the limiting conditions of the age-PM paradox and the need for a finer theoretical delineation of time-based tasks.

How Can Transcranial Magnetic Stimulation Be Used to Modulate Episodic Memory?: A Systematic Review and Meta-Analysis.

A systematic review and meta-analysis were conducted to synthesize the existing literature on how transcranial magnetic stimulation (TMS) has been used to modulate episodic memory. Given the numerous parameters of TMS protocols and experimental design characteristics that can be manipulated, a mechanistic understanding of how changes in the combination of parameters (e.g., frequency, timing, intensity, targeted brain region, memory task) modulate episodic memory is needed. To address this, we reviewed 59 studies and conducted a meta-analysis on 245 effect sizes from 37 articles on healthy younger adults (N = 1,061). Analyses revealed generally more beneficial effects of 1-Hz rTMS vs. other frequencies on episodic memory. Moderation analyses revealed complex interactions as online 20-Hz rTMS protocols led to negative effects, while offline 20-Hz rTMS led to enhancing effects. There was also an interaction between stimulation intensity and frequency as 20-Hz rTMS had more negative effects when applied below- vs. at-motor threshold. Conversely, 1-Hz rTMS had more beneficial effects than other frequencies when applied below- vs. at- or above-motor threshold. No reliable aggregate or hypothesized interactions were found when assessing stimulation site (frontal vs. parietal cortex, left vs. right hemisphere), stimulated memory process (during encoding vs. retrieval), the type of retrieval (associative/recollection vs. item/familiarity), or the type of control comparison (active vs. sham or no TMS) on episodic memory. However, there is insufficient data to make strong inference based on the lack of aggregate or two-way interactions between these factors, or to assess more complex (e.g., 3-way) interactions. We reviewed the effects on other populations (healthy older adults and clinical populations), but systematic comparison of parameters was also prevented due to insufficient data. A database of parameters and effects sizes is available as an open source repository so that data from studies can be continuously accumulated in order to facilitate future meta-analysis. In conclusion, modulating episodic memory relies on complex interactions among the numerous moderator variables that can be manipulated. Therefore, rigorous, systematic comparisons need to be further investigated as the body of literature grows in order to fully understand the combination of parameters that lead to enhancing, detrimental or null effects on episodic memory.

Non-perceptual Regions in the Left Inferior Parietal Lobe Support Phonological Short-term Memory: Evidence for a Buffer Account?

Buffer versus embedded processes accounts of short-term memory (STM) for phonological information were addressed by testing subjects' perception and memory for speech and non-speech auditory stimuli. Univariate and multivariate (MVPA) approaches were used to assess whether brain regions recruited in recognizing speech were involved in maintaining speech representations over a delay. As expected, a left superior temporal region was found to support speech perception. However, contrary to the embedded processes approach, this region failed to show a load effect, or any sustained activation, during a maintenance delay. Moreover, MVPA decoding during the maintenance stage was unsuccessful in this region by a perception classifier or an encoding classifier. In contrast, the left supramarginal gyrus showed both sustained activation and a load effect. Using MVPA, stimulus decoding was successful during the delay period. In addition, a functional connectivity analysis showed that, as memory load increased, the left temporal lobe involved in perception became more strongly connected with the parietal region involved in maintenance. Taken together, the findings provide greater support for a buffer than embedded processes account of phonological STM.

How can transcranial magnetic stimulation be used to causally manipulate memory representations in the human brain?

We present a focused review on the utility of transcranial magnetic stimulation (TMS) for modulating memory, with a particular focus on multimodal approaches in which TMS is paired with neuroimaging methods (electroencephalography and magnetic resonance imaging (MRI)) to manipulate and measure working memory processes. We contrast the utility of TMS for manipulating memory with other forms of noninvasive brain stimulation, as well as different forms of TMS including single-pulse, paired-pulse and repetitive TMS protocols. We discuss the potential for TMS to address fundamental cognitive neuroscience questions about the nature of memory processes and representations, while acknowledging the considerable variability of behavioral and neural outcomes in TMS studies. Also discussed are the limitations of this technology, current advancements that have helped to defray the impact of these limitations, and suggestions for future directions in research and methodology. This article is categorized under: Neuroscience > Clinical Neuroscience Neuroscience > Cognition Psychology > Memory.

Prospective Memory Is a Key Predictor of Functional Independence in Older Adults.

OBJECTIVES: Prospective memory (PM), the ability to execute delayed intentions, has received increasing attention in neuropsychology and gerontology. Most of this research is motivated by the claim that PM is critical for maintaining functional independence; yet, there is a dearth of empirical evidence to back up the claims. Thus, the present study tested whether PM predicts functional independence in older adults using validated behavioral performance measures for both PM and functional independence. METHODS: Fifty-eight healthy older adults performed a computerized PM paradigm, the Virtual Week task, as well as a timed version of an instrumental activities of daily living (TIADL) task. Furthermore, we assessed vocabulary, processing speed, and self-reported prospective remembering. RESULTS: TIADL scores correlated significantly with performance in the Virtual Week task, vocabulary, and processing speed. Hierarchical linear regressions revealed that vocabulary and Virtual Week performance were significant predictors for TIADL. However, self-reported PM scores did not predict everyday functioning. CONCLUSIONS: The findings indicate that PM is an important cognitive ability for successful and independent everyday life beyond vocabulary. Moreover, the results show a substantial incremental contribution of intact PM performance for the prediction of everyday functioning by using objective PM measures. (JINS, 2018, 24, 640-645).

Parietal-Occipital Interactions Underlying Control- and Representation-Related Processes in Working Memory for Nonspatial Visual Features.

Although the manipulation of load is popular in visual working memory research, many studies confound general attentional demands with context binding by drawing memoranda from the same stimulus category. In this fMRI study of human observers (both sexes), we created high- versus low-binding conditions, while holding load constant, by comparing trials requiring memory for the direction of motion of one random dot kinematogram (RDK; 1M trials) versus for three RDKs (3M), or versus one RDK and two color patches (1M2C). Memory precision was highest for 1M trials and comparable for 3M and 1M2C trials. And although delay-period activity in occipital cortex did not differ between the three conditions, returning to baseline for all three, multivariate pattern analysis decoding of a remembered RDK from occipital cortex was also highest for 1M trials and comparable for 3M and 1M2C trials. Delay-period activity in intraparietal sulcus (IPS), although elevated for all three conditions, displayed more sensitivity to demands on context binding than to load per se. The 1M-to-3M increase in IPS signal predicted the 1M-to-3M declines in both behavioral and neural estimates of working memory precision. These effects strengthened along a caudal-to-rostral gradient, from IPS0 to IPS5. Context binding-independent load sensitivity was observed when analyses were lateralized and extended into PFC, with trend-level effects evident in left IPS and strong effects in left lateral PFC. These findings illustrate how visual working memory capacity limitations arise from multiple factors that each recruit dissociable brain systems.SIGNIFICANCE STATEMENT Visual working memory capacity predicts performance on a wide array of cognitive and real-world outcomes. At least two theoretically distinct factors are proposed to influence visual working memory capacity limitations: an amodal attentional resource that must be shared across remembered items; and the demands on context binding. We unconfounded these two factors by varying load with items drawn from the same stimulus category ("high demands on context binding") versus items drawn from different stimulus categories ("low demands on context binding"). The results provide evidence for the dissociability, and the neural bases, of these two theorized factors, and they specify that the functions of intraparietal sulcus may relate more strongly to the control of representations than to the general allocation of attention.

Benefits from retrieval practice are greater for students with lower working memory capacity.

We examined the effects of retrieval practice for students who varied in working memory capacity as a function of the lag between study of material and its initial test, whether or not feedback was given after the test, and the retention interval of the final test. We sought to determine whether a blend of these conditions exists that maximises benefits from retrieval practice for lower and higher working memory capacity students. College students learned general knowledge facts and then restudied the facts or were tested on them (with or without feedback) at lags of 0-9 intervening items. Final cued recall performance was better for tested items than for restudied items after both 10 minutes and 2 days, particularly for longer study-test lags. Furthermore, on the 2-day delayed test the benefits from retrieval practice with feedback were significantly greater for students with lower working memory capacity than for students with higher working memory capacity (r = -.42). Retrieval practice may be an especially effective learning strategy for lower ability students.

Analysing concurrent transcranial magnetic stimulation and electroencephalographic data: A review and introduction to the open-source TESA software.

The concurrent use of transcranial magnetic stimulation with electroencephalography (TMS-EEG) is growing in popularity as a method for assessing various cortical properties such as excitability, oscillations and connectivity. However, this combination of methods is technically challenging, resulting in artifacts both during recording and following typical EEG analysis methods, which can distort the underlying neural signal. In this article, we review the causes of artifacts in EEG recordings resulting from TMS, as well as artifacts introduced during analysis (e.g. as the result of filtering over high-frequency, large amplitude artifacts). We then discuss methods for removing artifacts, and ways of designing pipelines to minimise analysis-related artifacts. Finally, we introduce the TMS-EEG signal analyser (TESA), an open-source extension for EEGLAB, which includes functions that are specific for TMS-EEG analysis, such as removing and interpolating the TMS pulse artifact, removing and minimising TMS-evoked muscle activity, and analysing TMS-evoked potentials. The aims of TESA are to provide users with easy access to current TMS-EEG analysis methods and to encourage direct comparisons of these methods and pipelines. It is hoped that providing open-source functions will aid in both improving and standardising analysis across the field of TMS-EEG research.

Reactivation of latent working memories with transcranial magnetic stimulation.

The ability to hold information in working memory is fundamental for cognition. Contrary to the long-standing view that working memory depends on sustained, elevated activity, we present evidence suggesting that humans can hold information in working memory via "activity-silent" synaptic mechanisms. Using multivariate pattern analyses to decode brain activity patterns, we found that the active representation of an item in working memory drops to baseline when attention shifts away. A targeted pulse of transcranial magnetic stimulation produced a brief reemergence of the item in concurrently measured brain activity. This reactivation effect occurred and influenced memory performance only when the item was potentially relevant later in the trial, which suggests that the representation is dynamic and modifiable via cognitive control. The results support a synaptic theory of working memory.

Improving Prospective Memory in Healthy Older Adults and Individuals with Very Mild Alzheimer's Disease.

OBJECTIVES: To test the utility of a memory-encoding strategy for improving prospective memory (PM), the ability to remember to execute future goals (e.g., remembering to take medications), which plays an important role in independent living in healthy older adults and those with very mild Alzheimer's disease (AD). DESIGN: Participants were randomly assigned to an encoding strategy condition or a standard encoding condition. SETTING: A longitudinal study conducted at an Alzheimer's disease research center. Testing took place at the center and in a university testing room. PARTICIPANTS: Healthy older adults (Clinical Dementia Rating (CDR) = 0.0, n = 38) and those classified as being in the very mild stage of AD (CDR = 0.5, n = 34). INTERVENTION: A simple strategy ("If I see Cue X, then I will perform Intention Y") was used to strengthen PM encoding and reduce the probability of forgetting to execute one's future plans. MEASUREMENTS: PM was assessed using Virtual Week, a laboratory task that requires the simulation of common PM tasks (the types of tasks performed in everyday life), such as taking one's medication at breakfast. RESULTS: The encoding strategy significantly reduced PM failures in healthy older adults and those with very mild AD and was effective regardless of the individual's episodic memory ability. CONCLUSION: This encoding strategy was successful in reducing PM errors in healthy older adults and those with mild AD with a range of memory abilities.

Semantic and phonological contributions to short-term repetition and long-term cued sentence recall.

The function of verbal short-term memory is supported not only by the phonological loop, but also by semantic resources that may operate on both short and long time scales. Elucidation of the neural underpinnings of these mechanisms requires effective behavioral manipulations that can selectively engage them. We developed a novel cued sentence recall paradigm to assess the effects of two factors on sentence recall accuracy at short-term and long-term stages. Participants initially repeated auditory sentences immediately following a 14-s retention period. After this task was complete, long-term memory for each sentence was probed by a two-word recall cue. The sentences were either concrete (high imageability) or abstract (low imageability), and the initial 14-s retention period was filled with either an undemanding finger-tapping task or a more engaging articulatory suppression task (Exp. 1, counting backward by threes; Exp. 2, repeating a four-syllable nonword). Recall was always better for the concrete sentences. Articulatory suppression reduced accuracy in short-term recall, especially for abstract sentences, but the sentences initially recalled following articulatory suppression were retained better at the subsequent cued-recall test, suggesting that the engagement of semantic mechanisms for short-term retention promoted encoding of the sentence meaning into long-term memory. These results provide a basis for using sentence imageability and subsequent memory performance as probes of semantic engagement in short-term memory for sentences.