Memory Load Research Articles

Attentional Refreshing in Working Memory and Its Interplay with Long-term Memory: A Behavioral and EEG Study.

Despite the growing interest in the study of attentional refreshing, the functioning of this working memory maintenance mechanism, including its cerebral underpinnings, is still debated. In particular, it remains unclear whether refreshing promotes long-term memory and whether it, in return, depends on long-term memory content to operate. Here, we used direct maintenance instructions and measured brain activity to investigate working memory maintenance with two objectives: (1) test if different behavioral and oscillatory patterns could be observed when participants were instructed to use attentional refreshing versus verbal rehearsal, and (2) observe whether and how refreshing is modulated when maintaining novel (pseudowords) versus familiar (words) memoranda. We conducted an EEG experiment using a modified Brown-Peterson task, in which we manipulated the type of maintenance engaged through explicit instructions (verbal rehearsal vs. refreshing), the type of memoranda (words vs. pseudowords), and the memory load (2 vs. 6). Using scalp EEG, we measured both neural oscillations during working memory maintenance and ERPs during the concurrent parity judgment task. For words, we showed that verbal rehearsal benefited more short-term recall whereas refreshing benefited more delayed recall. In keeping with these behavioral differences between maintenance instructions, frontal-midline theta power increased with memory load only when using verbal rehearsal, whereas occipito-parietal alpha desynchronization was larger with refreshing than verbal rehearsal. When maintaining pseudowords, verbal rehearsal also benefitted short-term recall more than refreshing. However, no long-term memory benefit of refreshing was observed for pseudowords, and oscillatory activity was not different under the two maintenance instructions. Our results provide new evidence supporting the independence between attentional refreshing and verbal rehearsal, and bring new insight into refreshing functioning. We discuss the possible interpretations of these results and the implications for the attentional refreshing literature.

Competition during verbal creative processes influences on ERS/ERD

ABSTRACT Humans are social creatures, and many tasks in our daily lives are solved together. The two main forms of social interaction in problem solving could be defined as competition and cooperation. In our study, we compared the ERS/ERD when performing a creative task (Alternative Uses Test, AUT) and a control task (“naming the objects from the presented category”) under competitive conditions in dyads (22 dyads, m-m, f-f, 18–23 years old) compared to the performance of tasks individually. The number of answers given by subjects under competitive conditions was significantly lower than during the execution of the tasks individually. The solving of the creative task in competition versus individual performance was accompanied by EEG synchronization (9–30 hz) clusters: 140–1220 ms and 900–1780 ms after stimulus presentation; 13.5–30 hz (1800–1980 ms), reflecting the creative thinking mode, and expected cognitive, emotional answers’ assessment. The control task under competitive conditions was accompanied by pronounced synchronization of low frequencies in the frontal areas (2–7 hz, 0–1980 ms), due to a greater working memory load; synchronization clusters in broadband (10–30 hz, 100–320 ms, 400–860 ms) and in the beta EEG band (17–30 hz, 1140–1980 ms). The competitive conditions significantly modulated the brain activity underlying creative and non-creative cognitive task performance, and resulted in greater induced EEG synchronization.

Consistent activation differences versus differences in consistent activation: Evaluating meta-analytic contrasts

Abstract Meta-analytic contrasts are a promising aspect of coordinate-based meta-analyses in neuroimaging research as they facilitate the statistical comparison of two meta-analytic results. They have been used for a multitude of comparisons, such as task conditions, cognitive processes, and groups. However, it remains to be tested how the results of meta-analytic contrasts relate to those of classic meta-analyses and vice versa. Here we present a comprehensive empirical investigation of this issue using four datasets from three different cognitive domains: working memory, working memory load, cognitive interference processing, and emotional face processing. For all four datasets, we compared the results of a standard meta-analysis across prototypical contrasts (condition A > condition B) reported in individual experiments with those of a contrast between two individual meta-analyses of the same conditions (meta-analysis condition A > meta-analysis condition B). In the meta-analytic contrasts similar brain regions as in the standard meta-analysis were found but with relatively distinct spatial activation patterns. Additionally, fewer regions were revealed in the meta-analytic contrasts, especially in areas where the conditions spatially overlapped. This can be ascribed to the loss of information on the strength of activations in meta-analytic contrasts, across which standard meta-analysis summarize. In one dataset, additional regions were found in the meta-analytic contrast, potentially due to task effects. Our results demonstrate that meta-analytic contrasts can yield similar results to standard meta-analyses but are sparser. This confirms the overall validity, but also limited ability to capture all regions found in standard meta-analyses. Notable differences observed in some cases indicate that such contrasts cannot be taken as an easy substitute for classic meta-analyses of experiment-level contrasts, warranting further research into the boundary conditions for agreement.

Does vibrotactile biofeedback for postural control interfere with cognitive processes?

BackgroundDirectional vibrotactile biofeedback for balance control can be instructed in the form of Repulsive (to move in the opposite direction of vibrations) or Attractive (to move in the direction of vibrations) stimulus encodings. However, which of these encodings is less cognitively demanding and poses less interference with high-level cognitive processes of conflict resolution remains unresolved.MethodsIn two between-subject studies with 30 (16 females) and 35 (23 females) healthy young adults, respectively, we investigated the cognitive load of Attractive and Repulsive vibrotactile biofeedback on 1) working memory (Study I) and 2) cognitive conflict resolution (Study II). Both studies also examined the effectiveness of both feedback stimulus encodings on balance control during quiet standing with eyes closed.ResultsBoth Attractive and Repulsive vibrotactile biofeedback increased balance stability (reduced trunk sway variability) in both the working memory and the conflict resolution study (Study I and II, respectively) with a greater increase of stability for the Repulsive encoding during multitasking demanding cognitive conflict resolution (Study II). Cognitive costs, measured in terms of the Linear Integrated Speed-Accuracy Score (LISAS), were greater for the Attractive encoding during multitasking with working memory demands. When cognitive conflict resolution was required as a secondary cognitive task, both stimulus encodings increased cognitive costs equally.ConclusionsThe effects of instructed Repulsive and Attractive stimulus encodings for the response-related interpretation of vibrotactile biofeedback of body sway were contrasted with respect to cognitive processing demands and balance stabilisation benefits. Both encodings improved balance stability but at certain cognitive costs. Regarding interference with specific high-level cognitive processes, however, a distinction has to be made between both encodings. Repulsive feedback encoding seems to cause less cognitive costs on working memory load and slightly greater stabilisation when cognitive conflict resolution is required. These results are discussed in the context of the known benefits of avoidance actions on cognitive control.

The Suppression Mechanisms of Passive Memory in Visual Working Memory: The Evidence from Electrophysiology.

Recent studies of visual working memory (VWM) underscore a structured hierarchy of storage states. Memories that are not immediately relevant to the task at hand but are essential for later use are transferred to a passive state, which operates independently of actively maintaining and manipulating current memories. Note that stimulating passive memory forcefully can reactivate it into an active state, resulting in a competition with active memory. Thus, to remain stable representations for both states within VWM, passive memory might involve sustained suppression during activity-silent maintenance to prevent reactivation from disrupting the current active storage. To investigate this, we analyzed lateralized electrophysiology signals while human participants (both women and men) were engaged in a sequential presentation memory task across two experiments. The results revealed positive contralateral delayed activity components and lateralized alpha enhancement for passive memory, neural indicative of suppression on passive storage. In addition, the suppression effect was independent of the memory load in both the active and the passive states. These findings support the notion of sustained suppression during activity-silent maintenance of passive memory, facilitating the stable maintenance of distinct storage states and advancing our understanding of the dynamic coding framework in VWM.

Semantic memory navigation in HIV: Conceptual associations and word selection patterns

Objective: This proof-of-concept study aimed to characterize semantic memory profiles in individuals with human immunodeficiency virus (HIV) and mild neurocognitive impairment. Method: Using a semantic relatedness task, we explored conceptual association and word selection patterns in people living with HIV (PLWH; n = 50) relative to people living without HIV (n = 46). We also studied whether word selection patterns in the PLWH group were associated with working memory capacity, cognitive flexibility and inhibitory control. Results: While accuracy did not differ between groups, PLWH produced significantly longer responses than controls (r = .32), with fewer hypernyms (d = .47), more troponyms (r = .37), and words that were more frequent (r = .39) and had more phonological neighbors (r = .22). These patterns survived covariation with participants’ cognitive status. None of these patterns correlated with measures of working memory, cognitive flexibility, inhibitory control or viral load (all correlation coefficients < .36). Conclusions: Together, these results suggest that PLWH might use alternative word finding strategies during semantic memory navigation, irrespective of the severity of other cognitive symptoms. Such findings contribute to the characterization of cognitive deficits in HIV and to the search for novel markers of the condition.

A Matter of Memory? Age-Invariant Relative Clause Disambiguation and Memory Interference in Older Adults.

Past research suggests that Working Memory plays a role in determining relative clause attachment bias. Disambiguation preferences may further depend on Processing Speed and explicit memory demands in linguistic tasks. Given that Working Memory and Processing Speed decline with age, older adults offer a way of investigating the factors underlying disambiguation preferences. Additionally, older adults might be subject to more severe similarity-based memory interference given their larger vocabularies and slower lexical access. Nevertheless, memory interference and sentence disambiguation have not been combined in studies on older adults before. We used a self-paced reading paradigm under memory load interference conditions. Older (n=30) and Younger (n=35) readers took part in the study online; reading times were recorded and measures of comprehension accuracy and load recall were collected. This setup allowed for the implicit measurement of attachment biases and memory interference effects interactively. Results show that similarity-based interference affected both age groups equally, but was more pronounced in NP2-biased structures, which took participants generally longer to read. Attachment preferences did not differ by group and were unaffected by Working Memory span. However, accuracy on recall prompts was predicted by Working Memory span in both groups. Findings of greater interference in syntactically dispreferred structures support unified processing models where parsing constraints naturally interact. The lack of age differences on our measures further aligns with research finding age-invariant implicit language processing.

Efficient Adaptation: Enhancing Multilingual Models for Low-Resource Language Translation

This study focuses on the neural machine translation task for the TR-EN language pair, which is considered a low-resource language pair. We investigated fine-tuning strategies for pre-trained language models. Specifically, we explored the effectiveness of parameter-efficient adapter methods for fine-tuning multilingual pre-trained language models. Various combinations of LoRA and bottleneck adapters were experimented with. The combination of LoRA and bottleneck adapters demonstrated superior performance compared to other methods. This combination required only 5% of the pre-trained language model to be fine-tuned. The proposed method enhances parameter efficiency and reduces computational costs. Compared to the full fine-tuning of the multilingual pre-trained language model, it showed only a 3% difference in the BLEU score. Thus, nearly the same performance was achieved at a significantly lower cost. Additionally, models using only bottleneck adapters performed worse despite having a higher parameter count. Although adding LoRA to pre-trained language models alone did not yield sufficient performance, the proposed method improved machine translation. The results obtained are promising, particularly for low-resource language pairs. The proposed method requires less memory and computational load while maintaining translation quality.

Pre-choice midbrain fluctuations affect self-control in food choice: A functional magnetic resonance imaging (fMRI) study.

Recent studies have shown that spontaneous pre-stimulus fluctuations in brain activity affect higher-order cognitive processes, including risky decision-making, cognitive flexibility, and aesthetic judgments. However, there is currently no direct evidence to suggest that pre-choice activity influences value-based decisions that require self-control. We examined the impact of fluctuations in pre-choice activity in key regions of the reward system on self-control in food choice. In the functional magnetic resonance imaging (fMRI) scanner, 49 participants made 120 food choices that required self-control in high and low working memory load conditions. The task was designed to ensure that participants were cognitively engaged and not thinking about upcoming choices. We defined self-control success as choosing a food item that was healthier over one that was tastier. The brain regions of interest (ROIs) were the ventral tegmental area (VTA), putamen, nucleus accumbens (NAc), and caudate nucleus. For each participant and condition, we calculated the mean activity in the 3-s interval preceding the presentation of food stimuli in successful and failed self-control trials. These activities were then used as predictors of self-control success in a fixed-effects logistic regression model. The results indicate that increased pre-choice VTA activity was linked to a higher probability of self-control success in a subsequent food-choice task within the low-load condition, but not in the high-load condition. We posit that pre-choice fluctuations in VTA activity change the reference point for immediate (taste) reward evaluation, which may explain our finding. This suggests that the neural context of decisions may be a key factor influencing human behavior.

Electrophysiological and hemodynamic mechanisms underlying load modulations in visuospatial working memory: A functional near-infrared spectroscopy (fNIRS) and electroencephalogram (EEG) study.

The n-back task has been widely used to study working memory. Previous studies investigating the electrophysiological (electroencephalogram [EEG]) and hemodynamic correlates (functional near-infrared spectroscopy [fNIRS]) of the n-back task have been generally based on verbal stimuli and only investigated EEG frequency bands. We simultaneously acquired the EEG and fNIRS in 35 participants (16 males; age = 26.4 ± 4.3 years; educational attainment = 18 ± 2 years) during a visuospatial n-back task. The task encompassed a control condition and a low (requiring to recall one previous stimulus) and a high (requiring to recall two previous stimuli) working memory load experimental conditions. Accuracy decreased and reaction times slowed in the high compared to both low load and control conditions. Regarding EEG, P3a showed higher amplitude in the experimental conditions compared to the control one, and P3b exhibited higher amplitude in the low compared to the high load condition. Regarding fNIRS, the high load condition showed higher deoxygenated hemoglobin compared to the control one. Moreover, the central frontopolar cortex showed higher activation compared with the left frontal cortex. Our study showed that working memory load during a visuospatial n-back task influenced behavioral and electrophysiological indices. Even if the load effect was only observed for deoxygenated hemoglobin on hemodynamic data, this was in line with previous studies and coherent with its electrophysiological correlates. Thus, our study confirms that EEG and fNIRS can be successfully used in multimodal acquisitions, but also highlights that future studies are needed to develop a novel version of the task. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Error monitoring under working memory load: Anelectrocortical investigation.

Error monitoring is essential for detecting errors and may facilitate behavioral adjustments that can reduce or prevent future errors. At times, error monitoring must occur while individuals are engaged in other, cognitively demanding tasks that might consume processing resources necessary for error monitoring. Here, we set out to determine whether concurrent working memory (WM) load interferes with error monitoring, as measured using event-related potentials, the error-related negativity (Ne/ERN), and error positivity (Pe). Fifty-four participants (n = 33 female) completed an arrowhead flanker task, with trials presented under low (2 letter) or high (6 letter) WM load. Participants were required to hold letter strings in memory and to recall these letters at the end of a set of flanker trials. Results showed that WM load reduced the Pe but did not affect the Ne/ERN. Therefore, WM load appeared to attenuate later, more elaborated stages of error processing, though initial error detection was unaffected. Additionally, high WM load slowed reaction times overall, but did not lead to a significant increase in errors. As such, slower responses may have helped participants maintain comparable accuracy for low-load versus high-load trials. Overall, results indicate that WM load interferes with the evaluation of error significance, which could interfere with behavioral adaptations over time.

Reminders eliminate age-related declines in prospective memory.

Prospective memory (PM)-the process of establishing intentions for future action and remembering to fulfill these intentions at the appropriate time-is necessary for many instrumental activities of daily living and for maintaining functional independence with increased age. Offloading PM demands onto the environment, such as setting a reminder alarm to take medication, offers an easy and effective way to mitigate age-related PM declines. However, a lack of basic knowledge about the cognitive and metacognitive processes that drive offloading decisions presents barriers to successful implementation. The present study addresses these issues by examining age differences in PM for offloaded (i.e., with reminders) and nonoffloaded (i.e., without reminders) intentions under low and high memory demands. With highly specific intentions that can be retrieved via bottom-up processes (Experiment 1), there were no age differences in PM without reminders, and younger and older adults equally benefitted from reminders under high memory load. With nonspecific intentions that require top-down attention for retrieval (Experiment 2), older adults had worse PM under high load without reminders. Critically, this age difference was eliminated with the use of reminders, likely due to increased reminder checking for older adults under high load. These findings suggest that offloading can circumvent cognitive capacity limitations and minimize computational effort to improve intention fulfillment in older adults. The theoretical and applied ramifications of these findings are discussed. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

GABAergic dysfunction in postmortem dorsolateral prefrontal cortex: implications for cognitive deficits in schizophrenia and affective disorders.

The microcircuitry within superficial layers of the dorsolateral prefrontal cortex (DLPFC), composed of excitatory pyramidal neurons and inhibitory GABAergic interneurons, has been suggested as the neural substrate of working memory performance. In schizophrenia, working memory impairments are thought to result from alterations of microcircuitry within the DLPFC. GABAergic interneurons, in particular, are crucially involved in synchronizing neural activity at gamma frequency, the power of which increases with working memory load. Alterations of GABAergic interneurons, particularly parvalbumin (PV) and somatostatin (SST) subtypes, are frequently observed in schizophrenia. Abnormalities of GABAergic neurotransmission, such as deficiencies in the 67 kDA isoform of GABA synthesis enzyme (GAD67), vesicular GABA transporter (vGAT), and GABA reuptake transporter 1 (GAT1) in presynaptic boutons, as well as postsynaptic alterations in GABA A receptor subunits further contribute to impaired inhibition. This review explores GABAergic abnormalities of the postmortem DLPFC in schizophrenia, with a focus on the roles of interneuron subtypes involved in cognition, and GABAergic neurotransmission within presynaptic boutons and postsynaptic alterations. Where available, comparisons between schizophrenia and affective disorders that share cognitive pathology such as bipolar disorder and major depressive disorder will be made. Challenges in directly measuring GABA levels are addressed, emphasizing the need for innovative techniques. Understanding GABAergic abnormalities and their implications for neural circuit dysfunction in schizophrenia is crucial for developing targeted therapies.

Personality may modulate learning and memory differences in two taxa of the African striped mouse genus Rhabdomys

AbstractDifferent environments place different cognitive demands on constituent taxa. Learning and memory involve cognitive processes with associated costs, and it is expected that different levels of learning will occur in taxa from different environments. Greater memory loads linked to increased environmental complexity require greater learning and memory capacities. We investigated the variation in learning and memory in sister taxa of striped mice (genus Rhabdomys). We studied two populations each of the mesic grassland‐occurring R. d. chakae and the mostly arid‐occurring R. pumilio. We conducted two sets of experiments. (1) In a novel object recognition (NOR) test, we assessed memory by recording the duration of exploration of similar and novel objects by test mice. (2) In an associative learning task, we assessed whether mice could associate specific scents with or without a food incentive or with different quantities of the food incentive in previous training phases. We measured the latency of mice to contact scents in a two‐sample choice in the test phase. In the NOR test, R. pumilio spent less time investigating similar objects in a training trial than R. d. chakae but increased absolute exploration of the novel object when presented with a novel and a familiar object in the retention trial, suggesting a sensitization to the novel object by R. pumilio. In the associative learning experiments, R. pumilio approached the stimuli faster than R. d. chakae, whereas mice from both taxa preferred scents associated with a seed versus no seed and scents associated with 5 seeds versus 1 seed. The data provide evidence of taxon‐level differences in learning and memory, likely related to environmentally modulated personality differences between the taxa.

Hands-on training: Effects on virtual presence, learning-centered emotions, cognitive load and learning outcome when learning with virtual reality

The effect of highly immersive virtual reality (VR) on learning is mixed, partly due to technical challenges with VR equipment like head-mounted displays (HMDs) and control devices. These can distract learners from the learning environment and its relevant learning material within. This challenge might cause lower virtual presence, higher negative emotions, and extraneous cognitive (working memory) load; all of which have a negative impact on learning outcome. This study investigates whether hands-on training of the interface improves virtual presence, learning emotions, cognitive load and learning outcomes when learning about chemistry in an immersive VR environment. Seventy-six eighth graders participated in a between-subjects design (hands-on training vs. no training). The results show that pupils with hands-on training (n = 38) showed significantly higher virtual presence, lower extraneous cognitive load and higher learning outcomes than those without any initial hands-on training (n = 38). However, no significant differences in pupils’ learning emotions and in intrinsic and germane cognitive load were found. Implications for the design of highly immersive VR environments are discussed from both a cognitive and an affective perspective.

Persistent resampling of external information despite 25 repetitions of the same visual search templates

We commonly load visual working memory minimally when to-be-remembered information remains available in the external world. In visual search, this is characterised by participants frequently resampling previously encoded templates, which helps minimize cognitive effort and improves task performance. If all search templates have been rehearsed many times, they should become strongly represented in memory, possibly eliminating the benefit of reinspections. To test whether repetition indeed leads to less resampling, participants searched for sets of 1, 2, and 4 continuously available search templates. Critically, each unique set of templates was repeated 25 trials consecutively. Although the number of inspections and inspection durations initially decreased strongly when a template set was repeated, behaviour largely stabilised between the tenth and last repetition: Participants kept resampling templates frequently. In Experiment 2, participants performed the same task, but templates became unavailable after 15 repetitions. Strikingly, accuracy remained high even when templates could not be inspected, suggesting that resampling was not strictly necessary in later repetitions. We further show that seemingly ’excessive’ resampling behaviour had no direct within-trial benefit to speed nor accuracy, and did not improve performance on long-term memory tests. Rather, we argue that resampling was partially used to boost metacognitive confidence regarding memory representations. As such, eliminating the benefit of minimizing working memory load does not eliminate the persistence with which we sample information from the external world – although the underlying reason for resampling behaviour may be different.

Visual working memory load persists during the comparison phase

Visual working memory load persists during the comparison phase

Visual exploration goes down with higher working memory load, while more saccades negatively impact recall

Visual exploration goes down with higher working memory load, while more saccades negatively impact recall

Auditory and visual working memory loads reduce fixation spread during free scene-viewing

Auditory and visual working memory loads reduce fixation spread during free scene-viewing

Memory Load Test - A Concept for Cognitive Reserve Evaluation with Auditory Perception.

&lt;b&gt;Introduction:&lt;/b&gt; Auditory scene analysis refers to the system through which the auditory system distinguishes distinct auditory events and sources to create meaningful auditory information. The exact number of directly perceived auditory stimuli is unknown, studies suggest it may range from 3 to 5. This number differs among individuals, and potentially may indirectly indicate the ability to store and process the complex information, related to the memory load, which is combined with human cognitive processes.&lt;b&gt;Aim:&lt;/b&gt; This study aims to further identify and quantify the number of sounds that can be perceived simultaneously in a complex auditory environment.&lt;b&gt;Material and methods:&lt;/b&gt; Participants were presented with structured acoustic recordings and were asked to identify the exact number of targeted stimuli heard throughout the test. The experiment was designed to assess the auditory load and determine the maximum number of auditory stimuli that a healthy human can perceive at once.&lt;b&gt;Results:&lt;/b&gt; Our study showed that on average, participants could identify up to three sounds at once with accuracy of responses declining progressively for four sounds or more.&lt;b&gt;Conclusions:&lt;/b&gt; This study aimed to investigate the human capacity to detect and identify multiple sound signals simultaneously in a noisy environment. By understanding this ability, we sought to assess cognitive reserve in individuals. Our objective was to determine if auditory load could serve as a diagnostic tool for cognitive evaluation. We believe that further research will establish the validity of this approach, and we anticipate that it is only a matter of time before it becomes a viable method for assessing cognitive function.