Biology subjects

Lewis, P.

Publications and source records attributed to Lewis, P..

At least 19 recordsLinked to original sources

bioRxiv2026

Mitochondrial cytochrome c accumulation accompanies reduced electron flux through complex IV without enhancing cell sensitivity to apoptosis

We show that chronic impairment of mitochondrial respiration is associated with marked accumulation of cytochrome c (Cytc) protein. Using SCO2-deficient HCT116 cells lacking functional cytochrome c oxidase and wild-type cells exposed to sustained hypoxia, we found that substantial mitochondrial Cytc accumulation parallels reduced electron flux through Cytc. SCO2-deficient cells exhibited equally elevated Cytc levels under normoxia (19% O2) and hypoxia (0.1-3% O2). Wild-type cells under sustained hypoxia accumulated Cytc, reaching levels comparable to those in SCO2-deficient cells. This effect was reversible upon reoxygenation. Increased Cytc protein levels were also observed in other cell models, including primary cortical neurons cultured under chronic hypoxia and in cerebral cortex tissue from hypoxia-exposed mice. Cytc accumulation occurred independently of CYCS transcription, mRNA translation, HIF activation, ROS production and changes in mitochondrial network. Pharmacological inhibition of complex III was likewise accompanied by increased Cytc levels, whereas mitochondrial uncoupling had no effect, suggesting that impaired electron transfer rather than membrane depolarisation per se underlies this association. Raman spectroscopy revealed enrichment of reduced Cytc and an increased Cytc-to-cytochrome b ratio in respiration-deficient cells. Further supporting a stabilisation-based mechanism, the fraction of membrane-unbound ferro-Cytc was decreased in SCO2-deficient cells, consistent with moderate cardiolipin enrichment, which is known to enhance retention of Cytc at the inner mitochondrial membrane. Despite elevated mitochondrial Cytc content, SCO2-deficient cells were less susceptible to apoptosis induced by intermittent hypoxia or dichloroacetate. Together, these findings indicate that reduced electron flux through complex IV is associated with Cytc accumulation through increased protein stability and membrane retention without enhancing apoptotic sensitivity.

Cell Biology↗

bioRxiv2025

Contrasting patterns of interleukin signalling in LRRK2 and idiopathic Parkinson's

Sporadic PD and LRRK2-associated Parkinsons Disease (PD) present with similar features although the familial form of disease is classically associated with less cognitive impairment, better REM sleep behaviour, and reduced incidence of hyposmia but more freezing gait and postural instability. Although being classified as the same disease from a clinical perspective there is an ongoing debate on whether these 2 conditions are linked to different causative molecular mechanisms. In this work we analysed the transcriptomics and proteomics profile of sporadic and LRRK2 PD patients to contrast and compare inflammatory markers in blood and CSF. Analyses showed molecular differences in the burden of inflammatory signals clearly differentiating the sporadic and the familial forms of disease. Finally, a cluster of closely connected proteins whose expression levels were changed in the familial forms of disease was highlighted. The levels of these inflammatory markers were associated with tau pathology suggesting this protein cluster might be a system model to evaluate the control of tau metabolism in the presence of LRRK2 mutations.

neuroscience↗

bioRxiv2025

Glutamic Acid at position 168 is a constitutive activator of Tank Binding Kinase 1 catalytic function

TANK binding kinase 1 (TBK1) is serine/threonine protein kinase member of the inhibitor of nuclear factor-{kappa}B kinase family, with links to the etiology of familial as well as idiopathic Amyotrophic Lateral Sclerosis. It contributes to several regulatory cellular processes such as autophagy, inflammation and apoptosis. Reduction or loss of TBK1 kinase activity is associated with increased risk of ALS, and so understanding the molecular basis of this activity is an important research priority. In this current study, the role of the E168 residue, located adjacent to the active site of TBK1, has been assessed using a combination of artificial and naturally occurring variants found at this codon - evaluated using multiple readouts for TBK1 kinase activity. The results suggest that the negative charge resulting from the presence of a glutamic acid at this codon is a constitutive activator of TBK1 activity.

biochemistry↗

bioRxiv2025

Your Emotions, My Brain: Generalizable Neural Signatures of Emotional Memory Reactivation During Sleep

Reactivation in sleep alters the structure of memories and can potentially be used to restructure upsetting representations. Reactivation can be triggered with auditory cues and then detected using machine learning and electroencephalography (EEG), but can we also detect the emotionality of reactivated memories? We examined this by presenting auditory cues that had been associated with negative or neutral stimuli in wake during subsequent NREM sleep and training a classifier to detect the emotionality of subsequent EEG responses. We were able to detect the reinstatement of emotionality 0.4-0.6 seconds after cue presentation. Importantly, we used a between-participant machine learning pipeline to identify shared neural signatures of emotionality across individuals without fine-tuning the model on testing participants. This approach eliminates the need for individualized wake localizer sessions, establishing a methodologically efficient framework for investigating emotional processing during sleep. Detection of emotional reactivation in sleep will help us to understand how such reactivation impacts upon the emotionality of the memories in the long term, potentially facilitating development of treatments for PTSD and depression through memory restructuring in sleep.

neuroscience↗

bioRxiv2025

HPV16 neutralizing monoclonal antibodies show evidence for common developmental pathways and public epitopes

Antibodies to human papillomavirus (HPV) primarily recognize surface exposed residues on five loops of the major capsid protein (L1) that vary significantly among HPV types. We determined which loops were required for neutralization for 70 HPV16 specific human monoclonal antibodies (mAbs) cloned from participants who received an HPV vaccine, and we describe molecular features of those antibodies. Chimeric HPV16 pseudovirus (cpsV), each having one surface loop bearing multiple amino acid substitutions, were used to determine neutralization specificity. The HPV16-FG-loop was the loop most frequently required for neutralization (44 of 70, 62.9%), however, all other surface loops were used for neutralization by multiple mAbs: HI (13, 18.6%), DE (15, 21.4%), EF (six, 8.6%), BC (four, 5.7%). Antibodies that required multiple loops were common (17, 24.3%). Three mAbs (4.3%) required sequences on the c-terminus of L1 and for another three mAbs the neutralization specificity could not be determined. Two types of mAbs appeared to be overrepresented: ten mAbs used VH 2-70 IGHV paired with VL {lambda}1-40, having characteristic mutations in complementarity determining region two (CDRL2). Cryogenic electron microscopy (Cryo-EM) revealed that two of these antibodies bound five Fabs per pentamer interacting with all five L1-surface loops. The other type of mAbs that appeared to be overrepresented were ten mAbs using VH 4-34, seven of which also used DH3-16*02 with conserved CDRH3 sequences. Cryo-EM for one of these mAbs, that required the FG-loop for neutralization, was shown to bind one Fab per pentamer at the apex, interacting with the DE- and FG-loops, with sequences of the Fab CDRH3 inserted between the DE- and FG-loops from two protomers. These two types of mAbs were found repeatedly in the four participants suggesting that these antibodies shared developmental pathways and bound to similar immunodominant epitopes on the virus. HighlightsMost human mAbs recognized L1 surface loops but three of 70 recognized sequences on the C-terminal arm of L1 Some antibodies induced by HPV vaccination follow shared developmental pathways. Human monoclonal antibodies using VH 2-70/VL {lambda}1-40 were found in all participants and bound with at a stoichiometry of five Fabs per capsomer. Human monoclonal antibodies using the diversity gene segment D3-16*02 were found in all participants and one Fab was shown to bind with a stoichiometry of one Fab per capsomer. In briefA panel of 70 HPV16 specific human monoclonal antibodies (mAbs), cloned from memory B cells or plasmablasts following HPV vaccination, was characterized by determining the surface loops of the major capsid protein (L1) required for neutralization and examined for shared molecular features. All five L1 loops were found to be used for neutralization by one or more antibodies, but the most frequent target of these antibodies was the FG loop followed by the HI and DE loops. Ten antibodies paired the heavy chain variable gene VH 2-70 with the light chain variable gene VL {lambda}1-40 and these antibodies had conserved mutations in the CDRL2 region of VL {lambda}1-40. Mutating the CDRL2 back to the predicted germline sequence significantly reduced neutralization. Cryo-EM analysis of two VH2-70/VL{lambda}1-40 mAbs showed five Fabs binding per L1 pentamer and a conserved epitope with Fabs interacting with all five variable loops across two adjacent protomers. Seven other mAbs had a heavy chain composed of the variable region VH4-34 with the diversity gene D3-16*02 resulting in the sequence motif WSGYR in the CDRH3. Mutation of that sequence to alanine ablated HPV16 neutralization activity. A cryo-EM structure of one of these antibodies showed one Fab binding the pentamer apex with the WSGYR motif inserting between three loops from two protomers. Antibodies with paired VH 2-70/VL {lambda}1-40 and the antibodies with CDRH3 containing the WSGYR sequence, were found in all four study participants suggesting that such antibodies may be commonly elicited following HPV vaccination.

immunology↗

bioRxiv2025

The Sequential Multispecies Coalescent

The multispecies coalescent (MSC) model applies coalescent theory to gene evolution within and among reproductively isolated populations ("species") to estimate a species tree in the face of gene tree conflict resulting from deep coalescence. Sequential Monte Carlo (SMC) uses particle filtering to sample a posterior distribution, providing a fully-Bayesian and easily parallelized alternative to traditional MSC tree inference approaches. The method we propose samples first from the joint posterior distribution of gene and species trees, then samples species trees conditional on gene trees sampled previously, employing SMC for both rounds. Analyses of simulated and empirical datasets yield results comparable to state-of-the-art Bayesian MCMC approaches. Sampling the multispecies coalescent using SMC retains the advantages of fully Bayesian methods and is parallelizable in ways that Bayesian MCMC methods are not but also adds unique challenges. We demonstrate the performance of SMC compared to other commonly-used species tree methods using two empirical datasets and 400 simulated datasets.

evolutionary biology↗

bioRxiv2024

Loss-of-function coding variants in the Ras of Complex Proteins/GTPase domain of Leucine Rich Repeat Kinase 2

The LRRK2 gene is a key contributor to genetic risk of Parkinsons disease, and a priority drug target for the disorder. Leucine Rich Repeat Kinase 2, the protein product of LRRK2, is a multidomain enzyme implicated in a range of cellular processes - including endolysosomal trafficking and damage response. Based on the report that truncation and structural variants resulting in loss of LRRK2 protein are observed in human populations, genomic sequence repositories were queried for coding variants affecting key catalytic residues in LRRK2 - resulting in the identification of three variants (K1374E, K1374R, and T1348P) predicted to ablate the capacity of LRRK2 to bind GTP. Biochemical and cellular characterization of these variants confirmed loss of GTP binding, as well as reduced or loss of kinase activity. These data demonstrate the presence of rare coding enzymatic loss-of-function variants in humans, with implications for our understanding of LRRK2 as a driver of disease and as a drug target.

biochemistry↗

bioRxiv2023

A Pillar and Perfusion Plate Platform for Robust Human Organoid Culture and Analysis

Human organoids have potential to revolutionize in vitro disease modeling by providing multicellular architecture and function that are similar to those in vivo. This innovative and evolving technology, however, still suffers from assay throughput and reproducibility to enable high-throughput screening (HTS) of compounds due to cumbersome organoid differentiation processes and difficulty in scale-up and quality control. Using organoids for HTS is further challenged by lack of easy-to-use fluidic systems that are compatible with relatively large organoids. Here, we overcome these challenges by engineering "microarray three-dimensional (3D) bioprinting" technology and associated pillar and perfusion plates for human organoid culture and analysis. High-precision, high-throughput stem cell printing and encapsulation techniques were demonstrated on a pillar plate, which was coupled with a complementary deep well plate and a perfusion well plate for static and dynamic organoid culture. Bioprinted cells and spheroids in hydrogels were differentiated into liver and intestine organoids for in situ functional assays. The pillar/perfusion plates are compatible with standard 384-well plates and HTS equipment, and thus may be easily adopted in current drug discovery efforts.

bioengineering↗

bioRxiv2023

Protein network analysis links the NSL complex to Parkinson's disease and mitochondrial biology

Whilst the majority of PD cases are sporadic, much of our understanding of the pathophysiological basis of disease can be traced back to the study of rare, monogenic forms of disease. In the past decade, the availability of Genome-Wide Association Studies (GWAS) has facilitated a shift in focus, toward identifying common risk variants conferring increased risk of developing PD across the population. A recent mitophagy screening assay of GWAS candidates has functionally implicated the non-specific lethal (NSL) complex in the regulation of PINK1-mitophagy. Here, a bioinformatics approach has been taken to investigate the proteome of the NSL complex, to unpick its relevance to PD progression. The mitochondrial NSL interactome has been built, mining 3 separate repositories: PINOT, HIPPIE and MIST, for curated, literature-derived protein-protein interaction (PPI) data. We built; i) the mitochondrial interactome, applying gene-set enrichment analysis (GSEA) to explore the relevance of the NSL mitochondrial interactome to PD and, ii) the PD-oriented interactome to uncover biological pathways underpinning the NSL /PD association. In this study, we find the mitochondrial NSL interactome to be significantly enriched for the protein products of PD associated genes, including the Mendelian PD genes LRRK2 and VPS35. Additionally, the PD associated interactome is enriched for mitochondrial processes; "mitochondrial cell death", "mitochondrial protein localisation", "membrane protein localisation" and "mitochondrial transport". Our data points to NSL complex members OGT and WDR5 as key drivers of this increased PD association. These findings strengthen a role for mitochondrial quality control in both familial and sporadic disease.

neuroscience↗

bioRxiv2022

Novel husbandry practices result in rapid rates of growth and sexual maturation without impacting adult behavior in the blind Mexican cavefish.

The development of animal model systems is dependent on the standardization of husbandry protocols that increase fecundity and reduce generation time. The blind Mexican tetra, Astyanax mexicanus, is an emerging genetic vertebrate model for evolution and biomedical research. Surface and cave populations of A. mexicanus have independently evolved, providing a model system for studying the genetic basis of divergent biological traits. While a rapid increase in the use of A. mexicanus has led to the generation of genetic tools including gene-editing and transgenesis, a slow and inconsistent growth rate remains a major limitation to the expanded application of A. mexicanus. The optimization of husbandry protocols that maximizes high-nutrient feed, smaller tank densities and larger tank sizes across development, would facilitate faster growth and expand the use of this model. Here, we describe standardized husbandry practices that optimize growth through a high protein diet, increased feeding, growth sorting of larvae and juveniles, and tank size transitions based on standard length. These changes to husbandry had a significant effect on growth rates and decreased the age of sexual maturity in comparison to our previous protocols. To determine whether our nutritional change and increased feeding impacted behavior, we tested fish in exploration and schooling assays. We found that a change in diet had no effect on the behaviors we tested, suggesting that increased feeding and rapid growth will not impact the natural variation in behavioral traits. Taken together, this standardized husbandry protocol will accelerate the development of A. mexicanus as a genetic model.

evolutionary biology↗

bioRxiv2022

Memory reactivation in slow wave sleep enhances relational learning

Sleep has been shown to boost the integration of memories, and thus to facilitate relational learning. This benefit is thought to rely upon memory reactivation during non-REM sleep. We set out to test this possibility by explicitly cueing such reactivation using a technique called targeted memory reactivation (TMR), in which sounds are paired with learned material in wake and then softly played back to the participant in sleep, triggering reactivation of the associated memories. Specifically, we tested whether TMR during slow wave sleep leads to enhancements in inferential thinking in a transitive inference task. Because the Up-phase of the slow oscillation is more responsive to external cues than the Down-phase, we also asked whether stimulation at this specific phase is more beneficial for such integration. Our data show that Up-phase TMR boosts the ability to make inferences, but only for the most distant inferential leaps. Such stimulation was also associated with detectable memory reinstatement, whereas Down-phase stimulation produced no such trace and led to below-chance performance. These findings demonstrate that cueing memory reactivation at the right time points in sleep can provide a direct benefit to difficult relational learning problems. Significance StatementMemory reactivation in sleep is thought to be important for integrative thinking. We examined this by explicitly cueing reactivation of a transitive inference task during slow wave sleep using Targeted Memory Reactivation (TMR). Because TMR at different phases of the slow oscillation has different impacts, we cued different hierarchies at Up and Down phases. Up-phase TMR enhanced inferential performance and was associated with classifiable memory reactivation. Conversely, Down-phase TMR lead to a short-term impairment in inferential thinking and no detectable reactivation. These findings provide the first evidence that TMR can boost transitive inference and is thus important for integration and reasoning.

neuroscience↗

bioRxiv2022

ESCPE-1 Mediates Retrograde Endosomal Sorting of the SARS-CoV-2 Host Factor Neuropilin-1

Endosomal sorting maintains cellular homeostasis by recycling transmembrane proteins and associated proteins and lipids (termed cargoes) from the endosomal network to multiple subcellular destinations, including retrograde traffic to the trans-Golgi network (TGN). Viral and bacterial pathogens subvert retrograde trafficking machinery to facilitate infectivity. Here, we develop a proteomic screen to identify novel retrograde cargo proteins of the Endosomal SNX-BAR Sorting Complex Promoting Exit-1 (ESCPE-1). Using this methodology, we identify Neuropilin-1 (NRP1), a recently characterised host factor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, as a cargo directly bound and trafficked by ESCPE-1. ESCPE-1 mediates retrograde trafficking of engineered nanoparticles functionalised with the NRP1-interacting peptide of the SARS-CoV-2 Spike protein. ESCPE-1 sorting of NRP1 may therefore play a role in the intracellular membrane trafficking of NRP1-interacting viruses such as SARS-CoV-2.

cell biology↗

bioRxiv2021

Multiple classes and isoforms of the RNA polymerase recycling motor protein HelD

Efficient control of transcription is essential in all organisms. In bacteria, where DNA replication and transcription occur simultaneously, the replication machinery is at risk of colliding with highly abundant transcription complexes. This can be exacerbated by the fact that transcription complexes pause frequently. When pauses are long-lasting, the stalled complexes must be removed to prevent collisions with either another transcription complex or the replication machinery. HelD is a protein that represents a new class of ATP-dependent motor protein distantly related to helicases. It was first identified in the model Gram-positive bacterium Bacillus subtilis and is involved in removing and recycling stalled transcription complexes. To date, two classes of HelD have been identified: one in the low G+C and the other in the high G+C Gram-positive bacteria. In this work we have undertaken the first comprehensive investigation of the phylogenetic diversity of HelD proteins. We show that genes in certain bacterial classes have been inherited by horizontal gene transfer, many organisms contain multiple expressed isoforms of HelD, some of which are associated with antibiotic resistance, and that there is a third class of HelD protein found in Gram-negative bacteria. Therefore, HelD proteins represent an important new class of transcription factor associated with genome maintenance and antibiotic resistance that are conserved across the Eubacterial kingdom.

molecular biology↗

bioRxiv2021

RNA polymerases from Low G+C Gram Positive Bacteria

The low G+C Gram positive bacteria represent some of the most medically and industrially important microorganisms. They are relied on for the production of food and dietary supplements, enzymes and antibiotics, as well as being responsible for the majority of nosocomial infections and serving as a reservoir for antibiotic resistance. Control of gene expression in this group is more highly studied than in any bacteria other than the Gram negative model Escherichia coli, yet until recently no structural information on RNA polymerase (RNAP) from this group was available. This review will summarise recent reports on the high resolution structure of RNAP from the model low G+C representative Bacillus subtilis, including the role of auxiliary subunits {delta} and {varepsilon}, and outline approaches for the development of antimicrobials to target RNAP from this group.

molecular biology↗

bioRxiv2021

Ongoing neural oscillations predict the post-stimulus outcome of closed loop auditory stimulation during slow-wave sleep.

The large slow oscillation (SO, 0.5-2Hz) that characterises slow-wave sleep is crucial to memory consolidation and other physiological functions. Manipulating slow oscillations can enhance sleep and memory, as well as benefitting the immune system. Closed-loop auditory stimulation (CLAS) has been demonstrated to increase the SO amplitude and to boost fast sleep spindle activity (11-16Hz). Nevertheless, not all such stimuli are effective in evoking SOs, even if they are precisely phase-locked. Here, we studied whether it is possible to use ongoing activity patterns to determine which oscillations to stimulate in order to effectively enhance SOs or SO-locked spindle activity. To this end, we trained classifiers using the morphological characteristics of the ongoing SO, as measured by electroencephalography (EEG), to predict whether stimulation would lead to a benefit in terms of the resulting SO and spindle amplitude. Separate classifiers were trained using trials from spontaneous control and stimulated datasets, and we evaluated their performance by applying them to held-out data both within and across conditions. We were able to predict both when large SOs will occur spontaneously, and whether a phase-locked auditory click will effectively enlarge them with an accuracy of ~70%. We were also able to predict when stimulation would elicit spindle activity with an accuracy of ~60%. Finally, we evaluate the importance of the various SO features used to make these predictions. Our results offer new insight into SO and spindle dynamics and provide a new method for online optimisation of stimulation. HIGHLIGHTS- Random forest classifiers can predict spontaneous and stimulated SOs and spindle amplitudes. - Morphological wave features predicted the response of SOs and spindles to CLAS. - SO amplitude during the click is the main predictor for post-stimulus SO amplitude. - Prediction of spindle activity did not differ in accuracy for stimulated vs spontaneous data.

neuroscience↗

bioRxiv2021

Mechanism of transcription modulation by the transcription-repair coupling factor

Elongation by RNA polymerase is dynamically modulated by accessory factors. The transcription-repair coupling factor (TRCF) recognizes distressed RNAPs and either rescues transcription or initiates transcription termination. Precisely how TRCFs choose to execute either outcome remains unclear. With Escherichia coli as a model, we used single-molecule assays to study dynamic modulation of elongation by Mfd, the bacterial TRCF. We found that nucleotide-bound Mfd converts the elongation complex (EC) into a catalytically poised state, presenting the EC with an opportunity to restart transcription. After long-lived residence in this catalytically poised state, ATP hydrolysis by Mfd remodels the EC through an irreversible process leading to loss of the RNA transcript. Further, biophysical studies revealed that the motor domain of Mfd binds and partially melts DNA containing a template strand overhang. The results explain pathway choice determining the fate of the EC and provide a molecular mechanism for transcription modulation by TRCF.

biophysics↗

bioRxiv2020

Membrane targeting activates Leucine-rich repeat kinase 2 with differential effects on downstream Rab activation

Genetic variation at the Leucine-rich repeat kinase 2 (LRRK2) locus contributes to enhanced lifetime risk of familial and sporadic Parkinsons disease. Previous data have demonstrated that recruitment to various membranes of the endolysosomal system results in LRRK2 activation. However, the mechanism(s) underlying LRRK2 activation at endolysosomal membranes and the cellular consequences of these events are still poorly understood. Here, we directed LRRK2 to lysosomes and early endosomes, triggering both LRRK2 autophosphorylation and phosphorylation of the direct LRRK2 substrates Rab10 and Rab12. However, when directed to the lysosomal membrane, pRab10 was restricted to perinuclear lysosomes, whereas pRab12 was visualized on both peripheral and perinuclear LRRK2-positive lysosomes, suggesting that lysosomal positioning provides additional regulation of LRRK2-dependent Rab phosphorylation. Anterograde transport of lysosomes to the cell periphery by increasing expression of ARL8B and SKIP or by knockdown of the motor adaptor protein JIP4 blocked recruitment and phosphorylation of Rab10 by LRRK2. Conversely, overexpression of the Rab7 effector protein RILP resulted in lysosomal clustering within the perinuclear area and increased LRRK2-dependent Rab10 recruitment and phosphorylation. The regulation of Rab10 phosphorylation in the perinuclear area depends on counteracting phosphatases, as knockdown of phosphatase PPM1H significantly increased pRab10 signal and lysosomal tubulation in the perinuclear region. Our novel findings suggest LRRK2 can be activated at multiple cellular membranes including lysosomes, and that lysosomal positioning further provides regulation of some Rab substrates likely via differential phosphatase activity in nearby cellular compartments.

cell biology↗

bioRxiv2020

Targeted memory reactivation of a serial reaction time task in SWS, but not REM, preferentially benefits the non-dominant hand

Targeted memory reactivation (TMR) is a technique by which sounds paired with learned information can be used to cue neural reactivation of that information during sleep. While TMR in slow-wave sleep (SWS) has been shown to strengthen procedural memories, it is unclear whether TMR in rapid eye movement (REM) sleep, a state strongly associated with motor consolidation, provides equivalent benefit. Furthermore, it is unclear whether this technique influences dominant and non-dominant hands equally. We applied TMR of a two-handed serial reaction time task (SRTT) during either SWS or REM in thirty-two human right handed adults (sixteen female) to examine the impact of stimulation in each sleep stage on right (dominant) and left hands. While TMR in SWS led to strong benefits in reaction times and sequence-specific skill, equivalent cueing in REM led to no benefit at all, suggesting that reactivation in this sleep stage is not important for the SRTT. Event-related potentials elicited by TMR cues for left and right hand movements differed significantly in REM, but not SWS, showing that these cues are at least processed in REM. Interestingly, TMR benefits were apparent only in the non-dominant hand, potentially due to the weaker performance measured in this hand at the outset. Overall, these findings suggest that memory replay in SWS, but not REM, is important for consolidation of the SRTT, and TMR-cued consolidation is stronger in the non-dominant hand. Significance statementTargeted memory reactivation (TMR) in sleep leads to memory consolidation, but many aspects of this process remain to be understood. We used TMR of a bimanual serial reaction time task to show that behavioural benefit is only observed after stimulation in SWS, even though electrophysiology shows that the TMR cues are processed in REM. Importantly, TMR selectively benefitted the non-dominant hand. These findings suggest that TMR in REM does not benefit this serial reaction time task, and that TMR in SWS preferentially consolidates weaker memory traces relating to the non-dominant hand.

neuroscience↗