Memory Content Research Articles

Acts of Remembering: From a Radically Enactive Point of View

ABSTRACT Cognitivists and radically enactivists understand acts of remembering in fundamentally different ways. It is a hallmark of cognitivism to seek to identify some independent component that puts the memory – the what’s remembered – into acts of remembering. Such a component is variably characterized as: a stored memory, a stored content, or stored information. Accordingly, and on this basis, cognitivists seek to distinguish memories from acts of remembering. This paper raises doubts about the very idea that we can make sense of the real, independent existence of stored memory contents or stored memory information and, in its place, motivates adoption of a radically enactivist approach to understanding various acts of remembering.

Adaptive memory reservation strategy for heavy workloads in the Spark environment

The rise of the Internet of Things (IoT) and Industry 2.0 has spurred a growing need for extensive data computing, and Spark emerged as a promising Big Data platform, attributed to its distributed in-memory computing capabilities. However, practical heavy workloads often lead to memory bottleneck issues in the Spark platform. This results in resilient distributed datasets (RDD) eviction and, in extreme cases, violent memory contentions, causing a significant degradation in Spark computational efficiency. To tackle this issue, we propose an adaptive memory reservation (AMR) strategy in this article, specifically designed for heavy workloads in the Spark environment. Specifically, we model optimal task parallelism by minimizing the disparity between the number of tasks completed without blocking and the number completed in regular rounds. Optimal memory for task parallelism is determined to establish an efficient execution memory space for computational parallelism. Subsequently, through adaptive execution memory reservation and dynamic adjustments, such as compression or expansion based on task progress, the strategy ensures dynamic task parallelism in the Spark parallel computing process. Considering the cost of RDD cache location and real-time memory space usage, we select suitable storage locations for different RDD types to alleviate execution memory pressure. Finally, we conduct extensive laboratory experiments to validate the effectiveness of AMR. Results indicate that, compared to existing memory management solutions, AMR reduces the execution time by approximately 46.8%.

Going through the motions: Biasing of dynamic attentional templates.

Attention must coordinate with memory to actively anticipate sensory input and guide action. Memory content may be biased away from veridical when it is functionally adaptive. So far, research has considered the biasing of still features in static displays. It is unknown whether the biasing of attentional templates can functionally adapt dynamic stimuli to facilitate search when targets and distractors compete within temporally extended contexts. Biasing of dynamic templates would require learning and modulatory mechanisms capable of abstracting over space and time to guide perception. Four experiments used a novel dynamic visual search task combined with a memory probe to test whether dynamic attentional templates can be biased. In Experiments 1-3, participants searched for a moving target among distractors that systematically moved either clockwise or counterclockwise relative to the target. On memory probe trials, participants recalled the target direction as biased away from the distractors. The distortion bias was adaptively changed (Experiment 2), grew over time (Experiment 2), and occurred even when motion direction was not the target-defining feature (Experiment 3). Experiment 4 manipulated the speed of targets and distractors to test the generalizability of the findings. Participants searched for a target of a given speed among faster or slower distractors. Memory probing revealed that participants remembered the target speed as biased away from that of distractors. Across different tasks, the magnitude of the biasing correlated positively with search performance. Our findings provide compelling evidence that dynamic stimulus attributes in attentional templates can become functionally biased when adaptive. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Goal Shifts Structure Memories and Prioritize Event-defining Information in Memory.

Every day, we encounter far more information than we could possibly remember. Thus, our memory systems must organize and prioritize the details from an experience that can adaptively guide the storage and retrieval of specific episodic events. Prior work has shown that shifts in internal goal states can function as event boundaries, chunking experiences into distinct and memorable episodes. In addition, at short delays, memory for contextual information at boundaries has been shown to be enhanced compared with items within each event. However, it remains unclear if these memory enhancements are limited to features that signal a meaningful transition between events. To determine how changes in dynamic goal states influence the organization and content of long-term memory, we designed a 2-day experiment in which participants viewed a series of black-and-white objects surrounded by a color border on a two-by-two grid. The location of the object on the grid determined which of two tasks participants performed on a given trial. To examine if distinct types of goal shifts modulate the effects of event segmentation, we changed the border color, the task, or both after every four items in a sequence. We found that goal shifts influenced temporal memory in a manner consistent with the formation of distinct events. However, for subjective memory representations in particular, these effects differed by the type of event boundary. Furthermore, to examine if goal shifts lead to the prioritization of goal-relevant features in longer lasting memories, we tested source memory for each object's color and grid location both immediately and after a 24-hr delay. On the immediate test, boundaries enhanced the memory for all concurrent source features compared with nonboundary items, but only if those boundaries involved a goal shift. In contrast, after a delay, the source memory was selectively enhanced for the feature relevant to the goal shift. These findings suggest that goals can adaptively structure memories by prioritizing contextual features that define a unique episode in memory.

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.

Discrimination of mnemonic similarity is associated with short-term and long-term memory precision.

Remembering specific memories with precision relies on the differentiation of similar memory contents - a process commonly referred to as pattern separation and behaviorally operationalized as lure discrimination in the mnemonic similarity task. Although pattern separation is typically investigated in the context of long-term memory (LTM), recent research extends these findings to short-term memory (STM) within a mixture model framework, emphasizing the distinction between memory quality and quantity. According to this framework, pattern separation is associated with memory precision across STM and LTM, regardless of the overall memory likelihood. However, these associations among memory quality measures may persist without the mixture model assumption. In an alternative model, a unitary memory strength measure quantified as a discrimination score (d') may also capture the association between pattern separation and memory quality, as pattern separation has been previously linked with strength-based memory performance. We tested these possibilities based on individual differences among 132 participants who underwent tasks measuring mnemonic pattern separation and STM/LTM quality. We found that behavioral estimates of pattern separation are significantly correlated with STM and LTM precision, irrespective of the likelihood of STM/LTM recall success. However, these associations are absent when considering the correlation between pattern separation and memory strength under a unitary model framework. By leveraging individual differences to constrain our understanding of cognitive models, our data unravel the intricate relationship between pattern separation and memory quality across timescales. These findings may therefore contribute to identifying sensitive behavioral measures for detecting subtle memory deficits in older adults or clinical populations.

Active maintenance of working memory contents affects functioning of attentional filtering.

Salient objects are well known to capture attention. Furthermore, a stimulus associated with the attention-capturing objects could infiltrate into working memory. This was recently formulated as filter disruption theory. In the present study, we asked whether such disruption of filter and incidental encoding of irrelevant information into working memory could be prevented. We hypothesized that an active maintenance of information could activate top-down control, thereby preventing the incidental infiltration of irrelevant information into working memory. In experiments, participants performed two consecutive visual searches while maintaining a visual item in working memory. In the first search, one of nontarget items was associated with a salient distractor. Importantly, the color of the nontarget item related to the salient distractor was incidentally encoded into working memory, exerting memory-driven attentional capture in the second search. However, such incidental encoding of irrelevant information into working memory did not occur when participants had to maintain a single color in working memory. This provides novel evidence that while the attentional filter is subject to perceptual distraction, active maintenance of information in working memory can prevent such disruption of the filter.

Surgical treatment of meningiomas improves neurocognitive functioning and quality of life – a prospective single-center study

Background and purposeEarly diagnosis and the refinement of treatment of patients with intracranial meningiomas have brought quality of life (QoL) and neurocognitive functioning as outcome measures into focus. The aim of this study is a comprehensive assessment of neurocognitive function, quality of life and the presence of depression in meningioma patients before and after surgery.MethodsPatients with MRI diagnosis of intracranial meningioma and indication for surgery were prospectively included. A clinical neuropsychologist performed neurocognitive assessments within 3 months before and 12 months after surgery. The test battery included investigation of selective and divided attention, verbal and figural memory, executive functioning, and word fluency. Self-report questionnaires to assess depressive symptoms, QoL, and disease coping were administered. Raw values and t-values were compared pre-and postoperatively. Outcome was stratified by tumor- and peritumoral brain edema (PTBE) volumes, postoperative resolution of PTBE and WHO grade. The study included 18 predominantly female patients (83%) with a median age of 59 years and mostly CNS WHO grade 1 meningiomas (83%).ResultsThere was a significant postoperative improvement in the ability to selectively react under stress, in working memory and improved delayed reproduction of verbal and visual memory content. QoL improved regarding a reduction in physical problems, an improvement in energy, and social functioning. There was a trend towards worse preoperative scores in all tests, and greater postoperative improvement in patients with PTBE. Tumor volume had no effect on the measured outcome. The patients did not suffer from depressive symptoms before the surgery but improved postoperatively and most patients had an active, problem-oriented coping strategy.ConclusionResection of intracranial meningiomas leads to an improvement in multiple neurocognitive domains and QoL. There is a trend towards poorer preoperative neurocognitive functioning and greater postoperative improvement in patients with PTBE. Depression appears to play a minor role in the context of neurocognitive functioning and disease coping.

No evidence that visual impulses enhance the readout of retrieved long-term memory contents from EEG activity

Abstract The application of multivariate pattern analysis (MVPA) to electroencephalography (EEG) data allows neuroscientists to track neural representations at temporally fine-grained scales. This approach has been leveraged to study the locus and evolution of long-term memory contents in the brain, but a limiting factor is that decoding performance remains low. A key reason for this is that processes like encoding and retrieval are intrinsically dynamic across trials and participants, and this runs in tension with MVPA and other techniques that rely on consistently unfolding neural codes to generate predictions about memory contents. The presentation of visually perturbing stimuli may experimentally regularize brain dynamics, making neural codes more stable across measurements to enhance representational readouts. Such enhancements, which have repeatedly been demonstrated in working memory contexts, could offer a tool to improve decoding in long-term memory tasks. In this study, we evaluated whether visual perturbations—or pings—improve our ability to predict the category of retrieved images from EEG activity during cued recall. Overall, our findings suggest that while pings evoked a prominent neural response, they did not reliably produce improvements in MVPA-based classification across several analyses. We discuss possibilities that could explain these results, including the role of experimental and analysis parameter choices and mechanistic differences between working and long-term memory.

Maintenance and transformation of representational formats during working memory prioritization

Visual working memory depends on both material-specific brain areas in the ventral visual stream (VVS) that support the maintenance of stimulus representations and on regions in the prefrontal cortex (PFC) that control these representations. How executive control prioritizes working memory contents and whether this affects their representational formats remains an open question, however. Here, we analyzed intracranial EEG (iEEG) recordings in epilepsy patients with electrodes in VVS and PFC who performed a multi-item working memory task involving a retro-cue. We employed Representational Similarity Analysis (RSA) with various Deep Neural Network (DNN) architectures to investigate the representational format of prioritized VWM content. While recurrent DNN representations matched PFC representations in the beta band (15–29 Hz) following the retro-cue, they corresponded to VVS representations in a lower frequency range (3–14 Hz) towards the end of the maintenance period. Our findings highlight the distinct coding schemes and representational formats of prioritized content in VVS and PFC.

Barcode activity in a recurrent network model of the hippocampus enables efficient memory binding.

Forming an episodic memory requires binding together disparate elements that co-occur in a single experience. One model of this process is that neurons representing different components of a memory bind to an "index" - a subset of neurons unique to that memory. Evidence for this model has recently been found in chickadees, which use hippocampal memory to store and recall locations of cached food. Chickadee hippocampus produces sparse, high-dimensional patterns ("barcodes") that uniquely specify each caching event. Unexpectedly, the same neurons that participate in barcodes also exhibit conventional place tuning. It is unknown how barcode activity is generated, and what role it plays in memory formation and retrieval. It is also unclear how a memory index (e.g. barcodes) could function in the same neural population that represents memory content (e.g. place). Here, we design a biologically plausible model that generates barcodes and uses them to bind experiential content. Our model generates barcodes from place inputs through the chaotic dynamics of a recurrent neural network and uses Hebbian plasticity to store barcodes as attractor states. The model matches experimental observations that memory indices (barcodes) and content signals (place tuning) are randomly intermixed in the activity of single neurons. We demonstrate that barcodes reduce memory interference between correlated experiences. We also show that place tuning plays a complementary role to barcodes, enabling flexible, contextually-appropriate memory retrieval. Finally, our model is compatible with previous models of the hippocampus as generating a predictive map. Distinct predictive and indexing functions of the network are achieved via an adjustment of global recurrent gain. Our results suggest how the hippocampus may use barcodes to resolve fundamental tensions between memory specificity (pattern separation) and flexible recall (pattern completion) in general memory systems.

Design transformations in monuments and memorials as monumental buildings: new perspectives on the place-making model

The monument, or the memorial, as a place of memory and emotional support, has been the focus of scholarly attention. Although existing studies have explored its space’s materialization, identity, history, and memory content, the materials about its design transformation have yet to be deeply excavated. Based on the relevant theories of place and place-making, the researchers constructed a knowledge system of the place-making model, the spatial vector pattern, and the worship behaviors of monuments. On this basis, a qualitative research methodology is adopted. Through case studies and participant observation, the design transformation of the monument/memorial is interpreted in the following five dimensions: function theme, morphology style, spatial relationship, visitor experience, and symbolic meaning. The results of this study show that the monument/memorial tends to promote in-depth public reflection and critical engagement with history, reflecting changes in how society perceives historical events. This research provides new perspectives for understanding the multidimensionality of the monument/memorial but also emphasizes the need to continue exploring its interaction with the socio-cultural context.

Using imagination and the contents of memory to create new scene and object representations: A functional MRI study

Humans can use the contents of memory to construct scenarios and events that they have not encountered before, a process colloquially known as imagination. Much of our current understanding of the neural mechanisms mediating imagination is limited by paradigms that rely on participants' subjective reports of imagined content. Here, we used a novel behavioral paradigm that was designed to systematically evaluate the contents of an individual's imagination. Participants first learned the layout of four distinct rooms containing five wall segments with differing geometrical characteristics, each associated with a unique object. During functional MRI, participants were then shown two different wall segments or objects on each trial and asked to first, retrieve the associated objects or walls, respectively (retrieval phase) and then second, imagine the two objects side-by-side or combine the two wall segments (imagination phase). Importantly, the contents of each participant's imagination were interrogated by having them make a same/different judgment about the properties of the imagined objects or scenes. Using univariate and multivariate analyses, we observed widespread activity across occipito-temporal cortex for the retrieval of objects and for the imaginative creation of scenes. Interestingly, a classifier, whether trained on the imagination or retrieval data, was able to successfully differentiate the neural patterns associated with the imagination of scenes from that of objects. Our results reveal neural differences in the cued retrieval of object and scene memoranda, demonstrate that different representations underlie the creation and/or imagination of scene and object content, and highlight a novel behavioral paradigm that can be used to systematically evaluate the contents of an individual's imagination.

Memory and Environment

Abstract The story of memory studies has been told as a tale of booms and waves. Most recently, a fourth wave of memory studies, responding to the environmental, ecocritical and post-humanist turn in the humanities, has been heralded (Craps et al., 2018). This Special Issue aims to trace and reflect upon the developments that have led to this fourth phase. At the outset, however, it needs to be acknowledged that we consider how memory and different forms of environment have long been understood as interrelated. Firstly, environments have featured as metaphors to focus attention on contexts of different kinds that are pertinent to acts of remembering. Secondly, environments have been considered as the background settings for memory processes: the places in which memory work is done. Thirdly, environments have been considered a functional parts of memory processes – where an environment serves as a media carrier of memory content that is actively involved in the transmission process. Although we chart how significant recent shifts in dominant modes of defining the term “environment” have impacted the field of memory studies and contributed to developments that have been construed as a fourth wave of memory studies, we argue that such a the fourth wave of memory studies does not represent a paradigmatic shift in our understanding of the relationship between memory and environment, but rather a shift in emphasis. As we move from memory place to mnemonic space to planetary memory (Bond et al., 2017; Chakrabarty & Latour, 2021; Crownshaw, 2014), the most significant shifts in our understanding of memory pertain to epistemology, category and scale. These altered frames of perception invite us to understand memory and environment as embedded, co-constitutive and co-constructed. Whilst there has been a consensus within the field of memory studies that only humans have the ability to “remember in ways that link individual remembering to cultural frameworks” (Kansteiner, 2002), a stronger emphasis on exploring the role of non-human entities in memory processes stands to challenge this conviction.

Beta-band neural variability reveals age-related dissociations in human working memory maintenance and deletion.

Maintaining and removing information in mind are 2 fundamental cognitive processes that decline sharply with age. Using a combination of beta-band neural oscillations, which have been implicated in the regulation of working memory contents, and cross-trial neural variability, an undervalued property of brain dynamics theorized to govern adaptive cognitive processes, we demonstrate an age-related dissociation between distinct working memory functions-information maintenance and post-response deletion. Load-dependent decreases in beta variability during maintenance predicted memory performance of younger, but not older adults. Surprisingly, the post-response phase emerged as the predictive locus of working memory performance for older adults, with post-response beta variability correlated with memory performance of older, but not younger adults. Single-trial analysis identified post-response beta power elevation as a frequency-specific signature indexing memory deletion. Our findings demonstrate the nuanced interplay between age, beta dynamics, and working memory, offering valuable insights into the neural mechanisms of cognitive decline in agreement with the inhibition deficit theory of aging.

A randomized clinical trial to evaluate feasibility, tolerability, and preliminary target engagement for a novel executive working memory training in adolescents with ADHD

ObjectiveWorking memory training for Attention-Deficit/Hyperactivity Disorder (ADHD) has focused on increasing working memory capacity, with inconclusive evidence for its effectiveness. Alternative training targets are executive working memory (EWM) processes that promote flexibility or bolster stability of working memory contents to guide behavior via selective attention. This randomized, placebo-controlled study was designed to assess feasibility, tolerability, and behavioral target engagement of a novel EWM training for ADHD. Method62 ADHD-diagnosed adolescents (12–18 years) were randomized to EWM training or placebo arms for 20 remotely coached sessions conducted over 4–5 weeks. Primary outcome measures were behavioral changes on EWM tasks. Secondary outcomes were intervention tolerability, trial retention, and responsiveness to adaptive training difficulty manipulations. ResultsLinear regression analyses found intervention participants showed medium effect size improvements, many of which were statistically significant, on Shifting and Filtering EWM task accuracy and Shifting and Updating reaction time measures. Intervention participants maintained strong self-rated motivation, mood, and engagement and progressed through the adaptive difficulty measures, which was further reflected in high trial retention. ConclusionsThe results suggest that these EWM processes show promise as training targets for ADHD. The subsequent NIMH R33-funded extension clinical trial will seek to replicate and extend these findings.

Level of memory contentment and ability among Parkinson’s disease patients partaking in Biokinetics exercise rehabilitation: a South African exploratory study

Level of memory contentment and ability among Parkinson’s disease patients partaking in Biokinetics exercise rehabilitation: a South African exploratory study

Fast Loosely-Timed Deep Neural Network Models with Accurate Memory Contention

The emergence of data-intensive applications, such as Deep Neural Networks (DNN), exacerbates the well-known memory bottleneck in computer systems and demands early attention in the design flow. Electronic System-Level (ESL) design using SystemC Transaction Level Modeling (TLM) enables effective performance estimation, design space exploration (DSE), and gradual refinement. However, memory contention is often only detectable after detailed TLM-2.0 approximately-timed or cycle-accurate RTL models are developed. A memory bottleneck detected at such a late stage can severely limit the available design choices or even require costly redesign. In this work, we propose a novel TLM-2.0 loosely-timed contention-aware (LT-CA) modeling style that offers high-speed simulation close to traditional loosely-timed (LT) models, yet shows the same accuracy for memory contention as low-level approximately-timed (AT) models. Thus, our proposed LT-CA modeling breaks the speed/accuracy tradeoff between regular LT and AT models and offers fast and accurate observation and visualization of memory contention. Our extensible SystemC model generator automatically produces desired TLM-1 and TLM-2.0 models from a DNN architecture description for design space exploration focusing on memory contention. We demonstrate our approach with a real-world industry-strength DNN application, GoogLeNet. The experimental results show that the proposed LT-CA modeling is 46× faster in simulation than equivalent AT models with an average error of less than 1% in simulated time. Early detection of memory contentions also suggests that local memories close to computing cores can eliminate memory contention in such applications.

Cross-regional coordination of activity in the human brain during autobiographical self-referential processing

For the human brain to operate, populations of neurons across anatomical structures must coordinate their activity within milliseconds. To date, our understanding of such interactions has remained limited. We recorded directly from the hippocampus (HPC), posteromedial cortex (PMC), ventromedial/orbital prefrontal cortex (OFC), and the anterior nuclei of the thalamus (ANT) during two experiments of autobiographical memory processing that are known from decades of neuroimaging work to coactivate these regions. In 31 patients implanted with intracranial electrodes, we found that the presentation of memory retrieval cues elicited a significant increase of low frequency (LF < 6 Hz) activity followed by cross-regional phase coherence of this LF activity before select populations of neurons within each of the four regions increased high-frequency (HF > 70 Hz) activity. The power of HF activity was modulated by memory content, and its onset followed a specific temporal order of ANT→HPC/PMC→OFC. Further, we probed cross-regional causal effective interactions with repeated electrical pulses and found that HPC stimulations cause the greatest increase in LF-phase coherence across all regions, whereas the stimulation of any region caused the greatest LF-phase coherence between that particular region and ANT. These observations support the role of the ANT in gating, and the HPC in synchronizing, the activity of cortical midline structures when humans retrieve self-relevant memories of their past. Our findings offer a fresh perspective, with high temporal fidelity, about the dynamic signaling and underlying causal connections among distant regions when the brain is actively involved in retrieving self-referential memories from the past.

Non-visual spatial strategies are effective for maintaining precise information in visual working memory

Visual working memory content is commonly thought to be composed of a precise visual representation of stimulus information (e.g., color, shape). Nevertheless, previous research has shown that individuals represent this visual information in different formats, historically dichotomized into “verbal” and “visual” formats. With growing popular knowledge of aphantasia, or the absence of sensory mental imagery, recent studies have demonstrated that individuals with aphantasia perform similarly to individuals with typical imagery on visual working memory tasks. This suggest that the use of non-visual strategies may be sufficient to perform visual working memory tasks, which were previously thought to be strictly visual. To investigate the effects of different strategies on performance in a visual working memory task, we recruited individuals across the visual imagery spectrum and tested their ability to identify relatively small (3°), medium (6°), or large (10°) changes in the degree of orientation of gratings held in working memory. Subsequently, participants indicated the extent to which they used five different strategies: visual, spatial, verbal, semantic, and sensorimotor. Results revealed that individuals with aphantasia and typical imagery performed similarly to each other across all task difficulty levels. Individuals with typical imagery dominantly used visuospatial strategies, but surprisingly, individuals with aphantasia overwhelmingly preferred the use of non-visual spatial and sensorimotor strategies over verbal strategies. These results suggest that non-visual spatial and sensorimotor strategies can be adopted in visual working memory tasks and these strategies are equally effective as visuospatial strategies. This calls for a rethinking of the “visual” versus “verbal” dichotomy, and provides evidence for the use of other non-visual mental representations in working memory tasks.