Working Memory Research Articles

Polysomnographically mediated cognitive improvements in individuals with insomnia symptoms following continuous theta-burst stimulation of the default mode network

IntroductionInsomnia is associated with mild cognitive impairment, although the mechanisms of this impairment are not well-understood. Timing of slow-wave and rapid eye movement sleep may help explain cognitive impairments common in insomnia. This investigation aimed to determine whether cognitive changes following continuous theta-burst stimulation (cTBS) are attributable to active stimulation, polysomnographic parameters of sleep, or both.MethodData presented here are part of a pilot clinical trial aiming to treat insomnia by targeting a node in the default mode network using an inhibitory 40-s (cTBS). A double-blind counterbalanced sham-controlled crossover design was conducted. Participants (N = 20) served as their own controls on two separate in-laboratory visits—one with active cTBS and the other with sham cTBS. Each visit included cognitive assessments before and after stimulation and following a night of sleep in the lab monitored with polysomnography.ResultsSlow wave sleep duration influenced working memory in the active cTBS condition, with shorter duration predicting improvements in working memory post sleep (B = −0.003, p = 0.095). Onset latency to rapid eye movement sleep predicted subsequent working memory, regardless of treatment condition (B = −0.001, p = 0.040). Results suggest that changes in attention and processing speed were primarily due to slow wave sleep onset (B = −0.001, p = 0.017) and marginally predicted by slow wave sleep duration (B = 0.002, p = 0.081) and sleep efficiency (B = 0.006, p = 0.090).ConclusionsFindings emphasize the important role that timing of slow-wave and rapid eye movement sleep have on information processing. Future work using larger sample sizes and more stimulation sessions is needed to determine optimal interactions between timing and duration of slow wave and rapid eye movement throughout the sleep period.Clinical trial registrationThis study is registered on ClinicalTrials.gov (NCT04953559). https://clinicaltrials.gov/study/NCT04953559?locStr=Arizona&country=United%20States&state=Arizona&cond=insomnia&intr=tms%20&rank=1

Experiential, perceptual, and cognitive individual differences in the development of declarative and automatized phonological vocabulary knowledge

Abstract The present study explores the influence of individual differences in experience, perceptual acuity, and working memory on the development of both declarative and automatized aspects of L2 phonological vocabulary knowledge. A total of 486 Japanese English-as-a-foreign-language (EFL) students took part in two vocabulary tests designed to measure declarative (meaning recognition) and automatized knowledge (lexicosemantic judgement task). Their performance was tied to the quantity and quality of their EFL experience, as well as their scores in auditory processing and working memory. While several significant, modest correlations between experience, aptitude, and vocabulary outcomes were observed, certain predictor variables were uniquely associated with either declarative or automatized vocabulary performance. Specifically, individuals with more extensive, typically language-focused EFL training and greater working memory demonstrated higher levels of declarative knowledge. Conversely, those who pursued extracurricular practice outside the classroom – exposing themselves to auditory materials and/or participating in study-abroad experiences – showed a more automatic execution of vocabulary knowledge.

COVID-19 related cognitive, structural and functional brain changes among Italian adolescents and young adults: a multimodal longitudinal case-control study

Coronavirus disease 2019 (COVID-19) has been associated with brain functional, structural, and cognitive changes that persist months after infection. Most studies of the neurologic outcomes related to COVID-19 focus on severe infection and aging populations. Here, we investigated the neural activities underlying COVID-19 related outcomes in a case-control study of mildly infected youth enrolled in a longitudinal study in Lombardy, Italy, a global hotspot of COVID-19. All participants (13 cases, 27 controls, mean age 24 years) completed resting-state functional (fMRI), structural MRI, cognitive assessments (CANTAB spatial working memory) at baseline (pre-COVID) and follow-up (post-COVID). Using graph theory eigenvector centrality (EC) and data-driven statistical methods, we examined differences in ECdelta (i.e., the difference in EC values pre- and post-COVID-19) and Volumetricdelta (i.e., the difference in cortical volume of cortical and subcortical areas pre- and post-COVID) between COVID-19 cases and controls. We found that ECdelta significantly between COVID-19 and healthy participants in five brain regions; right intracalcarine cortex, right lingual gyrus, left hippocampus, left amygdala, left frontal orbital cortex. The left hippocampus showed a significant decrease in Volumetricdelta between groups (p = 0.041). The reduced ECdelta in the left amygdala associated with COVID-19 status mediated the association between COVID-19 and disrupted spatial working memory. Our results show persistent structural, functional and cognitive brain changes in key brain areas associated with olfaction and cognition. These results may guide treatment efforts to assess the longevity, reversibility and impact of the observed brain and cognitive changes following COVID-19.

Davunetide sex-dependently boosts memory in prodromal Alzheimer’s disease

BackgroundThe tauopathy inhibitor, davunetide shows sex-dependent efficacy in women suffering from progressive supranuclear palsy. Extending these findings to prodromal Alzheimer’s disease, we submitted a double-blind, placebo-controlled, 12 weeks/16 weeks follow-up, davunetide clinical trial results in amnestic mild cognitive impairment (ClinicalTrials.gov ID NCT00422981), to a sex-dependent analysis.MethodsOne hundred forty-four individuals, separated into eight groups (1:2 placebo—and 2 doses, 5 mg davunetide/daily or 15 mg davunetide/twice-daily, with matching placebo intranasal volumes), were evaluated.ResultsSignificant dose-dependent cognitive increases were observed in men compared to women with a test of delayed (12 ss) visual matching to the sample. In a test of semantic working memory and attention (digit span), women showed a significant low-dose placebo effect, ensuing in a high dose significant davunetide improvement, over the matched placebo. Correlating anxiety with cognition showed sex-opposing results, with women depicting significant anxiety correlations with delayed matching to sample.DiscussionIn conclusion, sex-specific prodromal Alzheimer’s drug development is encouraged, with davunetide playing a lead initiative role.

Suppressing the Maintenance of Information in Working Memory Alters Long-term Memory Traces.

The sensory recruitment hypothesis conceptualizes information in working memory as being activated representations of information in long-term memory. Accordingly, changes made to an item in working memory would be expected to influence its subsequent retention. Here, we tested the hypothesis that suppressing information from working memory, which can reduce short-term access to that information, may also alter its long-term neural representation. We obtained fMRI data (n = 25; 13 female / 12 male participants) while participants completed a working memory removal task with scene images as stimuli, followed by a final surprise recognition test of the examined items. We applied a multivariate pattern analysis to the data to quantify the engagement of suppression on each trial, to track the contents of working memory during suppression, and to assess representational changes afterward. Our analysis confirms previous reports that suppression of information in working memory involves focused attention to target and remove unwanted information. Furthermore, our findings provide new evidence that even a single dose of suppression of an item in working memory can (if engaged with sufficient strength) produce lasting changes in its neural representation, particularly weakening the unique, item-specific features, which leads to forgetting. Our study sheds light on the underlying mechanisms that contribute to the suppression of unwanted thoughts and highlights the dynamic interplay between working memory and long-term memory.

Does Mild and Moderate Hearing Loss Affect Verbal Working Memory and Language Skills in Children?

Introduction: For a comprehensive approach in children with hearing loss (HL), some cognitive and language skills should also be considered, along with auditory skills. The main aim of this study was to evaluate the working memory and language skills in children with mild to moderate HL. Methods: Forty children with mild to moderate HL between the ages of 4 and 9 years were included in this study. The children with mild and moderate HL were evaluated in two groups. The Meaningless Word Repetition test, Test of Language Development-Primary test, and Meaningful Auditory Integration Scale were administered to assess working memory, language skills, and auditory perception, respectively. Also, the relationship between language and memory skills was evaluated. Results: The study found statistically significant correlations between language skills and working memory test scores. Additionally, statistically significant differences were found between children with mild and moderate HL in terms of language and memory skills (p < 0.001). Conclusion: The children with moderate HL demonstrated poorer performance compared to those with mild HL. Even if it is mild, the degree of HL affects children’s language and memory skills. It is emphasized that the relationship between language and working memory should be taken into consideration in auditory rehabilitation programs for these children.

Predicting the effectiveness of binaural beats on working memory.

Working memory is vital for short-term information processing. Binaural beats can enhance working memory by improving attention and memory consolidation through neural synchronization. However, individual differences in cognitive and neuronal functioning affect effectiveness of binaural beats, necessitating personalized approaches. This study aimed to develop a machine learning model to predict binaural beats's effectiveness on working memory using electroencephalography. Sixty healthy participants underwent a 5-min electroencephalography recording, an initial working memory evaluation, 15 min of binaural beats stimulation, and a subsequent working memory evaluation using digit span tests of increasing difficulty. Recall accuracy and response times were measured. Differential scores from pre-evaluation and post-evaluation labeled participants as active or inactive to binaural beats stimulation. electroencephalography data, recorded using 14 electrodes, provided brain activity estimates across theta, alpha, beta, and gamma frequency bands, resulting in 56 features (14 channels × 4 bands) for the machine learning model. Several classifiers were tested to identify the most effective model. The weighted K-nearest neighbors model achieved the highest accuracy (90.0%) and area under the receiver operating characteristic curve (92.24%). Frontal and parietal electroencephalography channels in theta and alpha bands were crucial for classification. This study's findings offer significant clinical insights, enabling informed interventions and preventing resource inefficiency.

Methamphetamine-related working memory difficulties underpinned by reduced frontoparietal responses.

Working memory difficulties are common, debilitating, and may pose barriers to recovery for people who use methamphetamine. Yet, little is known regarding the neural dysfunctions accompanying these difficulties. Here, we acquired cross-sectional, functional magnetic resonance imaging while people with problematic methamphetamine-use experience (MA+, n =65) and people without methamphetamine-use experience (MA-, n =44) performed a parametric n-back task (0-back through 2-back). Performance on tasks administered outside of the scanner, together with n-back performance, afforded to determine a latent dimension of participants' working memory ability. Behavioural results indicated that MA+ participants exhibited lower scores on this dimension compared to MA- participants (d = -1.39, p < .001). Whole-brain imaging results also revealed that MA+ participants exhibited alterations in load-induced responses predominantly in frontoparietal and default-mode areas. Specifically, while the MA- group exhibited monotonic activation increases within frontoparietal areas and monotonic decreases within default-mode areas from 0-back to 2-back, MA+ participants showed a relative attenuation of these load-induced activation patterns (d = -1.55, p < .001). Moreover, increased activations in frontoparietal areas from 0- to 2-back were related to greater working memory ability among MA+ participants (r = .560, p = .004). No such effects were observed for default-mode areas. In sum, reductions in working memory ability were observed alongside load-induced dysfunctions in frontoparietal and default-mode areas for people with problematic methamphetamine-use experience. Among them, load-induced activations within frontoparietal areas were found to have a strong and specific relationship to individual differences in working memory ability, indicating a putative neural signature of the working memory difficulties associated with chronic methamphetamine use.

Cell Type-Specific Profiles and Developmental Trajectories of Transcriptomes in Primate Prefrontal Layer 3 Pyramidal Neurons: Implications for Schizophrenia.

In schizophrenia, impaired working memory is associated with transcriptome alterations in layer 3 pyramidal neurons (L3PNs) in the dorsolateral prefrontal cortex (DLPFC). Distinct subtypes of L3PNs that send axonal projections to the DLPFC in the opposite hemisphere (callosal projection [CP] neurons) or the parietal cortex in the same hemisphere (ipsilateral projection [IP] neurons) play critical roles in working memory. However, how the transcriptomes of these L3PN subtypes might shift during late postnatal development when working memory impairments emerge in individuals later diagnosed with schizophrenia is not known. The aim of this study was to characterize and compare the transcriptome profiles of CP and IP L3PNs across developmental transitions from prepuberty to adulthood in macaque monkeys. The authors used retrograde labeling to identify CP and IP L3PNs in the DLPFC of prepubertal, postpubertal, and adult macaque monkeys, and used laser microdissection to capture these neurons for RNA sequencing. At all three ages, CP and IP L3PNs had distinct transcriptomes, with the number of genes differentially expressed between neuronal subtypes increasing with age. For IP L3PNs, age-related shifts in gene expression were most prominent between prepubertal and postpubertal animals, whereas for CP L3PNs such shifts were most prominent between postpubertal and adult animals. These findings demonstrate the presence of cell type-specific profiles and developmental trajectories of the transcriptomes of PPC-projecting IP and DLPFC-projecting CP L3PNs in monkey DLPFC. The evidence that IP L3PNs reach a mature transcriptome earlier than CP L3PNs suggests that these two subtypes differentially contribute to the maturation of working memory performance across late postnatal development and that they may be differentially vulnerable to the disease process of schizophrenia at specific stages of postnatal development.

Disentangling negative reinforcement, working memory, and deductive reasoning deficits in elevated BMI

Neuropsychological data suggest that being overweight or obese is associated with a tendency to perseverate behavior despite negative feedback. This deficit might be observed due to other cognitive factors, such as working memory (WM) deficits or decreased ability to deduce model-based strategies when learning by trial-and-error. In the present study, a group of subjects with overweight or obesity (Ow/Ob, n = 30) was compared to normal-weight individuals (n = 42) in a modified Reinforcement Learning (RL) task. The task was designed to control WM effects on learning by manipulating cognitive load and to foster model-based learning via deductive reasoning. Computational modelling and analysis were conducted to isolate parameters related to RL mechanisms, WM use, and model-based learning (deduction parameter). Results showed that subjects with Ow/Ob had a higher number of perseverative errors and used a weaker deduction mechanism in their performance than control individuals, indicating impairments in negative reinforcement and model-based learning, whereas WM impairments were not responsible for deficits in RL. The present data suggests that obesity is associated with impairments in negative reinforcement and model-based learning.

Persistent activity during working memory maintenance predicts long-term memory formation in the human hippocampus.

Working memory (WM) and long-term memory (LTM) are often viewed as separate cognitive systems. Little is known about how these systems interact when forming memories. We recorded single neurons in the human medial temporal lobe while patients maintained novel items in WM and completed a subsequent recognition memory test for the same items. In the hippocampus, but not in the amygdala, the level of WM content-selective persistent activity during WM maintenance was predictive of whether the item was later recognized with high confidence or forgotten. By contrast, visually evoked activity in the same cells was not predictive of LTM formation. During LTM retrieval, memory-selective neurons responded more strongly to familiar stimuli for which persistent activity was high while they were maintained in WM. Our study suggests that hippocampal persistent activity of the same cells supports both WM maintenance and LTM encoding, thereby revealing a common single-neuron component of these two memory systems.

Divergent subregional information processing in mouse prefrontal cortex during working memory

Working memory (WM) is a critical cognitive function allowing recent information to be temporarily held in mind to inform future action. This process depends on coordination between prefrontal cortex (PFC) subregions and other connected brain areas. However, few studies have examined the degree of functional specialization between these subregions throughout WM using electrophysiological recordings in freely-moving mice. Here we record single-units in three neighboring mouse medial PFC (mPFC) subregions—supplementary motor area (MOs), dorsomedial PFC (dmPFC), and ventromedial (vmPFC)—during a freely-behaving non-match-to-position WM task. The MOs is most active around task phase transitions, when it transiently represents the starting sample location. Dorsomedial PFC contains a stable population code, including persistent sample-location-specific firing during the delay period. Ventromedial PFC responds most strongly to reward-related information during choices. Our results reveal subregionally segregated WM computation in mPFC and motivate more precise consideration of the dynamic neural activity required for WM.

Improving working memory by electrical stimulation and cross-frequency coupling

Working memory (WM) is essential for the temporary storage and processing of information required for complex cognitive tasks and relies on neuronal theta and gamma oscillations. Given the limited capacity of WM, researchers have investigated various methods to improve it, including transcranial alternating current stimulation (tACS), which modulates brain activity at specific frequencies. One particularly promising approach is theta-gamma peak-coupled-tACS (TGCp-tACS), which simulates the natural interaction between theta and gamma oscillations that occurs during cognitive control in the brain. The aim of this study was to improve WM in healthy young adults with TGCp-tACS, focusing on both behavioral and neurophysiological outcomes. Thirty-one participants completed five WM tasks under both sham and verum stimulation conditions. Electroencephalography (EEG) recordings before and after stimulation showed that TGCp-tACS increased power spectral density (PSD) in the high-gamma region at the stimulation site, while PSD decreased in the theta and delta regions throughout the cortex. From a behavioral perspective, although no significant changes were observed in most tasks, there was a significant improvement in accuracy in the 14-item Sternberg task, indicating an improvement in phonological WM. In conclusion, TGCp-tACS has the potential to promote and improve the phonological component of WM. To fully realize the cognitive benefits, further research is needed to refine the stimulation parameters and account for individual differences, such as baseline cognitive status and hormonal factors.

Olfactory bulb stimulation mitigates Alzheimer's-like disease progression.

Deep brain stimulation (DBS) has demonstrated potential in mitigating Alzheimer's disease (AD). However, the invasive nature of DBS presents challenges for its application. The olfactory bulb (OB), showing early AD-related changes and extensive connections with memory regions, offers an attractive entry point for intervention, potentially restoring normal activity in deteriorating memory circuits. Our study examined the impact of electrically stimulating the OB on working memory as well as pathological and electrophysiological alterations in the OB, medial prefrontal cortex, hippocampus, and entorhinal cortex in amyloid beta (Aβ) AD model rats. Male Wistar rats underwent surgery for electrode implantation in brain regions, inducing Alzheimer's-like disease. Bilateral olfactory bulb (OB) electrical stimulation was performed for 1 hour daily to the OB of stimulation group animals for 18 consecutive days, followed by the evaluations of histological, behavioral, and local field potential signal processing. OB stimulation counteracted Aβ plaque accumulation and prevented AD-induced working memory impairments. Furthermore, it prompted an increase in power across diverse frequency bands and enhanced functional connectivity, particularly in the gamma band, within the investigated regions during a working memory task. This preclinical investigation highlights the potential of olfactory pathway-based brain stimulation to modulate the activity of deep-seated memory networks for AD treatment. Importantly, the accessibility of this pathway via the nasal cavity lays the groundwork for the development of minimally invasive approaches targeting the olfactory pathway for brain modulation.

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).

Dangerous remembering in volatile spaces: Activist memory work in the Iranian context

This article studies the interrelations of memory work and activism in the Iranian context by focusing on the way remembering victims of state violence informs political activism. Due to constant repression, the recurrence of state violence and the criminalisation of oppositional activities and non-conforming lifestyles, the Iranian context is saturated with contentious memories that cannot be brought into public space. Oppositional memory work, especially regarding the victims of direct state violence, has thus become dangerous, counts as defiance and requires alternative spaces for taking shape. This article maps out and explains how activist memory work in this context entails carving out activist memoryscapes and intertwines personal suffering with acts of remembering the other and how memory is used as a resource in broader modes of oppositional politics, justice-seeking and endeavours towards social change. Examples of activist memory work in the Woman, Life, Freedom protests, a short documentary film and a commemorative exhibition are analysed in the article to showcase the different mnemonic dynamics at stake and to highlight the importance of mediation and cultural forms in the formation of activist memory work.

Digital activism in the future past: How Dutch Extinction Rebellion activists connect past, present and future in their memory work on Instagram

This article investigates the ways in which Dutch Extinction Rebellion activists discursively engage with the past, present and future on Instagram and leverage the platform’s affordances for mnemonic purposes. We argue that Extinction Rebellion activists, in their communication on the platform, connect these temporal planes retrospectively and prospectively. First, Extinction Rebellion activists use the past as a resource for present action aimed at producing lasting change. This relates to cultural reservoirs and repertoires of past injustices. Second, the present is perceived by Extinction Rebellion activists as a concern for future memory. The recording and documenting of climate injustices and the actions of the movement itself are examples of this. Both positive and negative imagined futures are used by Extinction Rebellion activists to legitimise and delegitimise past and present (in)action. In other words, Extinction Rebellion activists’ future imaginaries not just shape present action, but also shape their memory work. Instagram’s affordances of archivability, connectivity and spreadability are used by Extinction Rebellion to support their digital memory work. These socio-technical affordances are thus appropriated as mnemonic affordances for rhetorical and practical purposes. We support these claims through in-depth interviews with Extinction Rebellion activists and a thematic analysis of Instagram content shared by them.

Working memory related brain-behavior associations in the context of socioeconomic and psychosocial deprivation

Burgeoning neuroimaging research documents the associations between working memory (WM)-associated neural and behavioral responses. However, these associations have yielded small and inconsistent effect sizes. We hypothesize that one reason for the weakened brain-behavior associations stems from different environmental contexts. Specifically, little research has examined how exposure to adverse rearing environments accounts for variability in brain-behavior relations. Deprivation, characterized by an absence of cognitive and positive social stimulation, has been shown to compromise children's neurocognitive development. Hence, informed by an ecological approach to developmental neuroscience, the present study aims to investigate if psychosocial and socioeconomic deprivation serves as moderators in the associations between neural responses and behaviors during a WM task. Using data from the Adolescent Brain Cognitive Development study (N = 11, 878, Mage = 9.48, 47.8% female, 52.0% White), we found that psychosocial, but not socioeconomic deprivation, significantly attenuated the positive association between WM-related neural activation within the frontoparietal network and attendant behavioral performance. Specifically, children exposed to higher levels of psychosocial deprivation exhibited weaker brain-behavior relations during a WM task. This finding suggests that a certain level of neural response during cognitive tasks may correspond to different levels of behavioral performance depending on children's rearing environment, highlighting the importance of contextual factors in understanding the brain and cognitive development.

Action Planning Renders Objects in Working Memory More Attentionally Salient.

A rapidly growing body of work suggests that visual working memory (VWM) is fundamentally action oriented. Consistent with this, we recently showed that attention is more strongly biased by VWM representations of objects when we plan to act on those objects in the future. Using EEG and eye tracking, here, we investigated neurophysiological correlates of the interactions between VWM and action. Participants (n = 36) memorized a shape for a subsequent VWM test. At test, a probe was presented along with a secondary object. In the action condition, participants gripped the actual probe if it matched the memorized shape, whereas in the control condition, they gripped the secondary object. Crucially, during the VWM delay, participants engaged in a visual selection task, in which they located a target as fast as possible. The memorized shape could either encircle the target (congruent trials) or a distractor (incongruent trials). Replicating previous findings, we found that eye gaze was biased toward the VWM-matching shape and, importantly, more so when the shape was directly associated with an action plan. Moreover, the ERP results revealed that during the selection task, future action-relevant VWM-matching shapes elicited (1) a stronger Ppc (posterior positivity contralateral), signaling greater attentional saliency; (2) an earlier PD (distractor positivity) component, suggesting faster suppression; (3) a larger inverse (i.e., positive) sustained posterior contralateral negativity in incongruent trials, consistent with stronger suppression of action-associated distractors; and (4) an enhanced response-locked positivity over left motor regions, possibly indicating enhanced inhibition of the response associated with the memorized item during the interim task. Overall, these results suggest that action planning renders objects in VWM more attentionally salient, supporting the notion of selection-for-action in working memory.

Solidarity: Memory work, periodicals and the protest lexicon in the long 1960s

This article examines the lexical memory work performed by the British New Left as it differentiated itself from the organised labour movement post-1956. It argues that activists use memory to reframe the meaning of keywords in the ‘protest lexicon’, and that this is an important, though usually implicit, activist cultural practice. Based on previous work in conceptual history and cognitive science, it begins by situating lexical memory work as an activity on the border between narrative historical memory, semantic memory and implicit collective memory. It then discusses the resignification of the word solidarity during the long 1960s, when lexical work was a key feature of the New Left’s apostasy from traditional Marxism. Finally, it examines the case of the British heterodox Marxist journal, Solidarity, outlining how it intervened in the protest lexicon by wrenching free the keyword solidarity from previous meanings, changing its historical referent and, ultimately, resignifying it.