Neuropsychologia

The ability to generate novel creative ideas (divergent thinking) is closely linked with our ability to imagine novel future events (episodic simulation). Here, we employed an individual differences approach to examine whether divergent thinking and episodic simulation are differentially associated with episodic and semantic retrieval ability. In response to object word cues, participants generated meanings and definitions (semantic memory), remembered a past event (episodic memory), imagined a novel future event (episodic simulation), or generated novel uses (divergent thinking). Replicating previous findings, divergent thinking ability was predicted by the number of episodic details generated during episodic simulation. When directly comparing episodic and semantic memory, the strongest predictor of divergent thinking was semantic memory. In contrast, episodic simulation ability was predicted by both episodic and semantic memory. We interpret these findings as support for the semantic scaffold hypothesis of imagination, according to which semantic memory provides the necessary scaffold or framework for flexible expressions of cognition such as divergent thinking and episodic simulation. As episodic simulation, relative to divergent thinking, was associated with both episodic and semantic retrieval, these findings are taken to reflect common reliance on event construction processes recruited during both episodic remembering and imagining.

Humanity has always admired and created artwork, but the neurocognitive mechanisms behind artistic experience are still elusive. Professional artists and their intimate relationship with their artworks provide a unique opportunity to study the nature of art experience due to their expertise in both art making and art appreciation. During two fMRI tasks, professional artists (N=20) made aesthetic judgments on their own and other artists paintings (aesthetic appreciation task); they also mentally reconstructed the moments when they conceived their artworks or, as a control condition, when they visited now-familiar places for the first time (reconstruction by imagery task). During art appreciation of their own (as compared to other artists) paintings, participants showed stronger recruitment of bilateral posterior parietal cortices, the left lateral occipitotemporal cortex, and the dorso-central sector of the right insula, that is, action-related brain regions also involved in encoding the emotional components of movements. The reconstruction of their own artistic creation (as compared to episodic memory retrieval) involved the left fronto-parietal network associated with motor cognition. Altogether, these results suggest that the mental representations of the actions involved in creating art are integral to the overall artistic experience of painters, supporting an embodied view of the artists experience of art.

Retrieval training (i.e., cued recall) is theorised to induce rapid memory consolidation, similarly to sleep. Across consolidation, related neural representations become increasingly similar; yet, this representational change has never been directly compared between sleep and retrieval training. In this study, 30 subjects (27F, 18-34, M=22.17) completed four separate sessions in which they (1) learnt object-word pairs, followed by (2) immediate recognition testing, (3) one of four 120-min interventions (retrieval training, restudy, sleep, or wake), and (4) delayed recognition testing. We compared EEG phase similarity between similar and different objects to assess the time, frequency, and anatomical distribution of representational similarity across encoding (learning to immediate recognition), and each intervention (immediate to delayed recognition). We hypothesised that EEG phase patterns for similar objects would become more similar (i.e., representational merging) across retrieval training and sleep interventions, and predict a greater endorsement of similar-object lures. Indeed, we found increased representational similarity between similar objects across the encoding shift in the theta-band and occipital sources. Crucially, additional representational merging was only observed across the retrieval training intervention, in the alpha-band and parieto-occipital sources. Despite retrieval training leading to reduced performance in discriminating similar-objects lures, greater representational merging across retrieval training predicted greater discrimination of similar-object lures. Together, these findings suggest that sleep and retrieval training induce different memory transformations across the same timescale. Retrieval training may generally provoke rapid gist extraction, with greater neocortical integration supporting episodic discrimination. Conversely, sleep may selectively maintain task-relevant episodic and semantic details in the short-term.

Spatialization in working memory refers to the spatial coding of non-spatial information along a mental horizontal line when encoding verbal material. This phenomenon is thought to support working memory by facilitating order encoding. Although it has been observed for both visually and auditorily presented stimuli, no direct comparison has yet examined whether these modalities rely on similar neural mechanisms. In this study, we investigated whether spatialization in visual and auditory modalities involves shared or distinct patterns of activity within the working-memory network. Forty-nine participants performed both a visual and an auditory working memory SPoARC task of the same verbal material, allowing to study the cortical patterns associated with distinct serial positions at both encoding and recognition across sensory modalities. Whole-brain analyses revealed similar frontoparietal networks across conditions. In addition, a representational similarity analysis (RSA) was conducted to assess the similarity of neural patterns between early and late serial positions in a sequence and across sensory modalities. This multivoxel pattern analysis revealed modality-dependent patterns distinguishing early and late positions in the inferior frontal gyrus. Additional modality-specific effects were observed in the anterior intraparietal sulcus in the visual modality and in the posterior hippocampus in the auditory modality. Drawing on the framework proposed by Bottini & Doeller (2020), we propose that order decoding in the IPS might reflect a low-dimensional spatial coding of order (e.g., along a horizontal axis), whereas order decoding in the hippocampus might reflect higher-dimensional spatial representations or temporal representations.

The cognitive factors that enable us to be proficient readers can greatly vary across individuals. The case of skilled deaf readers is emblematic as it shows that high reading performances can be achieved even when lifelong acoustic experience is absent or minimal. Here we present a set of experiments investigating how alternative strategies of orthographic processing can lead to high levels of reading proficiency. Four EEG studies compared behavioral and brain correlates of orthographic processing in skilled deaf readers and matched hearing controls. Using single word recognition and priming paradigms, we investigated two pillars of orthographic processing: letter identity and letter position. Our findings show that, although both groups had similarly accurate reading performance, skilled deaf readers were faster, and they consistently differ from hearing controls in the way they process letter identity. This group difference was observed in both lexical and sublexical tasks and was specifically related to the identity of orthographic representations, regardless of the visual form of the written stimuli (such as character visual similarity and letter case). These findings uncover alternative strategies that make possible high reading performance, even in the absence of acoustic experience. Public Significance StatementThis research identifies alternative orthographic strategies that improve single-word reading efficiency and can potentially serve as effective compensatory tools when phonological processing is impaired.

Previous research has demonstrated that children exhibit superior - as compared to adults - consolidation of newly acquired motor sequences across post-learning periods of wakefulness. Given that consolidation is thought to be supported by the reactivation of learning-related patterns of brain activity during the rest periods following active task practice, we hypothesized that the childhood advantage in offline consolidation may be linked to greater reactivation during post-learning wakefulness. Twenty-two children (7-11 years) and 23 adults (18-30 years) completed two sessions of a motor sequence learning task, separated by a 5-hour wake interval. Multivoxel analyses of task-related and resting-state functional magnetic resonance imaging data were employed to assess the persistence of learning-related patterns of neural activity into post-task rest epochs, reflective of reactivation processes. Behavioral results demonstrated the previously reported childhood advantage in offline consolidation over a post-learning wake interval. Imaging results revealed that children exhibited greater persistence of task-related hippocampal - but not putaminal - activity into post-learning rest as compared to adults. These findings suggest that the childhood advantage in awake motor memory consolidation may be supported, at least partially, by enhanced reactivation of task-dependent hippocampal activity patterns during offline epochs.

Transcranial electrical stimulation (tES) can modulate neural dynamics, yet its effects on memory are heterogeneous. Individual differences in cognitive profiles, may well be one of the potential causes by setting boundary conditions on the extent and mode of the tES-induced modulation of network dynamics. In a sham-controlled, within-subject study (N = 42), we compared the effects of tDCS (1.5 mA), tACS ({+/-}1.0 mA at individual theta frequency, ITF), and otDCS (1.5 mA {+/-} 0.5 mA at ITF) over the left posterior parietal cortex on object-location (OL) associative memory, and examined whether six cognitive abilities (figural reasoning, semantic, visuospatial, processing speed, working memory, mnemonic binding) moderate stimulation outcomes. Associative memory recognition improved selectively under theta-otDCS, whereas tDCS and tACS showed no significant group-level effects. Yet all tES protocols exhibited considerable interindividual variability. Relative to cognitive abilities, processing speed moderated tES effects in line with neural efficiency predictions, yielding greater gains in cognitively faster individuals. In contrast, mnemonic binding and figural reasoning moderated benefits in a compensatory manner, with larger improvements in lower-ability individuals. Overall, the effects of tES on associative memory were specific to the tES protocol and outcome measure while being strongly shaped by cognitive profile via complementing magnification and compensation mechanisms.

Episodic memory depends on neural representations encoded in the hippocampus. Experimental and computational evidence suggests that the hippocampus encodes pattern-separated representations that support later recall of episodic event elements. While extant data in humans predominantly focus on assaying the relationship between the similarity of spatial neural patterns at encoding and later memory performance, similarity of neural patterns in the temporal domain may also reveal encoding computations predictive of future memory. To examine how the similarity among temporal patterns of hippocampal activity during encoding relates to later episodic retrieval (associative cued recall and recognition memory), hippocampal activity was recorded from human participants (n=7) with implanted intracranial electrodes while they encoded arbitrary (A-B) paired-associates. Subsequent memory analyses first revealed that hippocampal high-frequency broadband power (HFB; 70-180Hz) was linked to a graded increase in memory strength; HFB power was greater during the encoding of pairs later correctly recalled relative to events later recognized and was lowest for events later forgotten. Second, and critically, subsequent memory analyses further revealed that more distinctive temporal patterns in the hippocampus during encoding -- indexed by the similarity of the HFB timeseries elicited by a given event to that elicited by other events -- were associated with superior subsequent memory performance. Finally, exploratory analyses revealed stimulus category effects on hippocampal HFB power during encoding and retrieval cuing. These results indicate that the temporal distinctiveness of hippocampal traces during encoding is important for subsequent retrieval of episodic event elements, consistent with theories that posit that pattern separation facilitates future remembering.

A central question in psycholinguistics in visual word recognition is whether morphologically complex words are obligatorily decomposed into stems and affixes during visual word recognition or whether whole-word access can occur when forms are frequent and familiar. The present study investigated how morphological complexity and lexical frequency jointly shape neural responses by leveraging Korean nominal inflection, whose transparent stem-suffix structure permits a clean dissociation between base (stem) frequency and surface (whole-word) frequency. Twenty-five native Korean speakers completed a rapid event-related fMRI lexical decision task involving simple and inflected nouns that varied parametrically in both frequency measures. Representational similarity analysis (RSA) revealed robust encoding of surface frequency--but not base frequency--in the inferior frontal gyrus (IFG) pars opercularis and supramarginal gyrus (SMG), with significantly stronger correlations for inflected than simple nouns. Univariate analyses converged with this result: surface frequency selectively increased activation for inflected nouns in inferior parietal regions, whereas base frequency showed no reliable effects in any ROI. These findings challenge models positing obligatory pre-lexical decomposition, instead supporting accounts in which morphological processing is shaped by post-lexical, usage-driven lexical statistics. Taken together, our findings shed light on a distributed perspective on morphological processing, suggesting that structural and statistical factors jointly constrain access to morphologically complex forms.

It is critical to identify which factors induce specific brain states as these large-scale patterns of coordinated neural activity drive downstream processing and behavior. The retrieval state, a brain state engaged when attempting to retrieve the past, is thought to specifically support episodic memory, remembering experiences within a spatiotemporal context, as opposed to semantic memory, remembering general knowledge. However, we hypothesize that the retrieval state reflects internal attention engaged to access stored episodic and semantic information. To test these alternatives, we recorded scalp electroencephalography while participants made episodic, semantic, or perceptual judgments, and applied an independently validated mnemonic state classifier to measure retrieval state engagement. We found that retrieval state engagement was greater for both episodic and semantic judgments compared to perceptual judgments. These findings suggest that the retrieval state reflects a domain-general internal attention process that supports not just episodic memory, but internally directed cognition.

BackgroundAudiovisual integration is essential for daily functions such as speech comprehension. It relies on a temporal constraint whereby events from different sensory modalities are perceptually bound within a limited temporal window, the audiovisual temporal binding window, defining the range of stimulus onset asynchronies perceived as synchronous. While correlational neuroimaging studies (fMRI, EEG) have implicated a distributed network in audiovisual integration, the causal neural underpinnings of the temporal binding window remain largely unknown. ObjectiveTo identify cortical regions causally supporting audiovisual simultaneity judgment. Methods: Direct electrical stimulation (DES) was prospectively applied to 62 cortical sites during awake brain surgery in 39 patients. Patients performed an audiovisual simultaneity judgment task with varying stimuli onset asynchronies alongside standard sensory-motor, language, and visuospatial tasks. Montreal Neurological Institute coordinates were obtained for all stimulated areas. ResultsDES selectively impaired audiovisual simultaneity judgments while sparing other standard tasks, in 7 highly focal, right-hemispheric cortical sites (<1 cm2). Three sites were situated around the intraparietal sulcus, and four near the supplementary motor area. Stimulation of left-hemisphere sites produced non-selective impairments, also affecting language-related tasks. ConclusionsThese findings provide causal evidence for a right-lateralized frontoparietal network, involving focal regions near the intraparietal sulcus and supplementary motor area, in audiovisual temporal integration. Given the established roles of these regions in attentional and decisional processes, this study refines their contribution to the temporal binding window network and underscores the clinical importance of preserving this network during awake brain surgery.

Visual false memory refers to our tendency to falsely recognize novel stimuli that are visually similar to seen stimuli. Visual false memory also occurs when stimuli are meaningful, suggesting that semantic information interferes with the encoding of visual details. However, the neural mechanisms of this semantic interference effect are largely unknown. In the present fMRI study, participants were scanned while encoding visually similar fonts presented with words (word-fonts) or pseudowords (pseudoword-fonts), and later, when recognizing old, new similar (lures), and new dissimilar (novel) fonts displayed in the same meaningless letter string. We performed (1) representational similarity analysis (RSA) at encoding to identify visual, visuosemantic, and semantic representations associated with subsequent visual true and false font recognition, (2) encoding-retrieval similarity (ERS) analysis to assess their reinstatement during retrieval, and (3) mediational analyses to examine hippocampal contributions. The study yielded three main findings. First, visuosemantic representations supported true font recognition when stored in right fusiform gyrus, but false recognition of word-fonts when stored in the left fusiform gyrus. Second, mirroring this pattern, reinstatement in right fusiform gyrus was associated with true font recognition, whereas reinstatement in left fusiform gyrus was linked to false recognition of word-fonts. Finally, posterior hippocampal activation reduced false font memory mainly for pseudoword-associated fonts via decreased reinstatement in perceptual regions, while anterior hippocampal activity increased false memory of word-fonts via enhanced reinstatement in semantic regions. Taken together, these findings reveal how distinct hippocampal-cortical pathways differentially bias memory towards perceptual specificity or semantic generalization. Significance StatementFalse memories are often triggered by visual similarity, but this study shows that meaning encoded during learning can distort memory for visual details, even when retrieval cues are meaningless. Participants learned fonts associated with words or pseudowords and judged whether similar lure fonts, shown on a meaningless letter string, were seen before. Although behavioral performance was similar across conditions, brain imaging revealed a key dissociation: the left fusiform gyrus and anterior hippocampus promote semantic generalization that increases false recognition, whereas the right fusiform gyrus and posterior hippocampus support perceptual specificity that protects against it. These findings reveal how distinct hippocampal-cortical pathways differentially bias memory toward truth or illusion.

Cortical tracking of acoustic features is essential for the neural processing of continuous stimuli such as speech and music. For example, it has been shown that children with dyslexia show atypical cortical tracking. This tracking may therefore reflect a fundamental auditory temporal processing mechanism supporting literacy more generally. In the current pre-registered study, we tested the hypothesis that cortical tracking of speech and music predicts reading ability in healthy young adults (N = 32), evaluated through a lexical decision task. Participants first completed an online session in which they performed a lexical decision task to assess their reading skills. This was followed by an electroencephalography (EEG) session, in which participants listened to a naturalistic short story and a music track. Using mutual information, we showed that neural activity aligned to both speech and music across a wide range of frequencies. Interestingly, cortical tracking was stronger for speech at very low frequencies, while it was stronger for music at higher frequencies. Critically, cortical tracking predicted reaction times in the lexical decision task in a frequency-dependent manner: stronger delta-band tracking (~1-3 Hz) for both speech and music was associated with faster reaction times, whereas stronger alpha-band tracking (~12 Hz) for speech was associated with slower reaction times. These findings remained significant even when controlling for stimulus type, age, musical experience and reading enjoyment. These results suggest that cortical tracking of speech and music reflect a domain-general temporal processing mechanism that is associated with reading ability beyond stimulus-specific features, and beyond development. These findings advance the neurobiological underpinnings of literacy and could potentially be leveraged for developing new reading interventions.

During the first period of life, human infants rapidly and effortlessly acquire the languages they are exposed to. Although memory is central to this process, the nature of early verbal memory systems and the factors that determine retention and forgetting remain largely unknown. Behavioural and brain measures have demonstrated memory formation in newborns. However, word traces fade in the face of acoustic overlap, leading to interference and forgetting. Here, we investigate whether speakers identity changes facilitate the separation into distinct acoustic episodes and the creation of non-overlapping verbal memories. Newborns (0-4 days-old) were tested in a familiarization-interference-test protocol, while neural cortical activity was recorded using functional Near-Infrared Spectroscopy (fNIRS). The results showed higher neural activation to novel words than to familiar ones during the test phase, indicating that the infants recognized the familiar words despite potentially interfering sounds. The recognition response was measured over the left inferior frontal gyrus (IFG) and superior temporal gyrus (STG) areas known to be crucial for encoding auditory information and language processing. The neural response also included the right IFG and STG, involved in interpreting vocal social cues and speaker recognition. The results indicate that speaker identity is a key feature in the formation of verbal memories from birth, facilitating separability, possibly through early source-content binding (i.e., what-who), a precursor to fully mature episodic memory. Impact StatementSpeaker identity is a distinguishing feature at birth and highlights the episodic nature of humans first-stored verbal memories.

Children with developmental language disorder (DLD) have persistent language learning difficulties and often perform poorly on pseudoword repetition, a task that probes phonological, memory, and speech-motor processes that support vocabulary acquisition. Research on the neural basis of pseudoword repetition in DLD is limited. We used whole-brain functional MRI (fMRI) to examine pseudoword repetition and repetition-based learning in 46 children with DLD (ages 10-15 years) and 71 age-matched children with typical language development. During scanning, children heard and repeated pseudowords paired with visual referents, allowing us to track learning-related changes in neural activity across repetitions. Repeated pseudoword production yielded comparable behavioural learning across groups, with faster productions by later repetitions. Post-scan, form-referent recognition was comparable across groups, whereas pseudoword repetition accuracy was lower in DLD. Pseudoword repetition engaged a distributed neural network, including inferior frontal cortex bilaterally (greater on the left), premotor and sensorimotor cortex, and posterior temporal and occipital regions. Group differences emerged primarily in regions where activity was task negative (i.e., below baseline or deactivated): lateral occipito-parietal cortex (posterior angular gyrus), medial parieto-occipital cortex (retrosplenial), and right posterior cingulate cortex. Learning-related decreases in activity were similar across groups, but region-of-interest analyses showed reduced leftward lateralisation of activity in inferior frontal gyrus in DLD. These findings suggest weaker disengagement of the default mode network during a linguistically demanding task in DLD. Although repetition-based pseudoword learning recruited similar neural mechanisms in both groups, these mechanisms may operate less efficiently in DLD, alongside reduced hemispheric specialisation in inferior frontal cortex. HighlightsO_LISimilar repetition-related neural attenuation across groups during pseudoword learning. C_LIO_LIReduced default-mode network suppression during pseudoword repetition in DLD. C_LIO_LIReduced left-hemisphere specialisation of inferior frontal cortex in DLD. C_LIO_LIRepetition-based learning in DLD supported by less efficient neural networks. C_LI

Auditory associative word learning has been shown in infants and proven to be a difficult task in young adults, where learning is only successful under specific conditions. In order to better understand the transition from successful infant auditory associative word learning to the challenging adult learning, we tested 5-6-year-olds and 9-10-year-olds in a sequential associative task to investigate their ability in associating novel pseudowords with environmental sounds. Additionally, we explored short-term episodic recognition memory, language development, sex, and musical training and their effects on behavioral and electrophysiological measures of word learning. EEG data were collected to assess word learning in an initial training phase (consistent vs. inconsistent pairings) and a subsequent testing phase (matching vs. violated pairings) with additional button-press reactions for behavioral learning data. While learning effects were seen in the first half of the training phase in younger children, no early effects of learning were found in older children. Only musically trained 9-10-year-olds indicated word learning in the second half of the training phase. In the testing phase, only non-musically trained 9-10-year-olds revealed trend-level N400-like responses. Short-term memory (auditory-verbal, auditory-nonverbal, and visual-nonverbal) and language development improved with age, but only visual-nonverbal short-term recognition memory was positively correlated with improved auditory associative word learning. Unlike cross-modal visual associative word learning, our results, together with earlier findings in infants and young adults, suggest a difficulty in auditory associative word learning beyond infancy, which is sustained from childhood to young adulthood.

Despite decades of animal and human intracranial work highlighting the critical role theta oscillations (4-12 Hz) play in memory encoding and recall stage during navigation, the link between scalp recorded human theta oscillations and spatial encoding and recall is lacking. In the present study, we used right posterior theta (RPT) - a scalp-level theta signal believed to be generated in the medial temporal cortex - to examine spatial encoding and recall during virtual spatial navigation. In particular, we recorded EEG from 27 healthy subjects performing a novel virtual Linear Track Memory (LTM) task. During the encoding stage of the task, a reward cue was presented at one of five pillar locations along a linear track. During the recall stage, subjects were presented with images of the five pillars and five new pillars, and were asked to press a button when the rewarded target pillar location appeared. If correct, subjects received 5 cents for that trial. Memory performance was assessed using reaction time, d-prime (d), and response bias ({beta}), and RPT was measured following the onset of the reward cue at bilateral scalp electrodes P7 and P8. Consistent with previous work, RPT peaked approximately 170-300 ms over the right hemisphere (P8) after cue onset, which was significantly increased for reward cues during the encoding stage and for the target pillar during the recall stage. Importantly, general linear model regressions revealed that peak RPT power during the encoding stage significantly predicted higher d and {beta} scores during recall, supporting the relationship between RPT peak power and memory performance. Together, these findings support the proposal that RPT activity reflects the encoding of salient information for the purpose of spatial navigation and a promising candidate biomarker for memory-related functioning in health and disease (e.g., Alzheimers disease).

Both episodic memory and word retrieval have been linked to power decreases in the alpha and beta oscillatory bands, but these patterns have rarely been related to each other, partly due to a lack of methodological approaches available. In this explorative study, we investigate the similarities and dissimilarities in the oscillatory fingerprints of the retrieval of words and episodes by directly comparing the activity patterns across time, frequency, and space. We acquired electroencephalography (EEG) data of participants performing a language and an episodic memory task based on the same stimulus material. With a newly developed approach, we directly compared the source-reconstructed oscillatory activity using mutual information and a feature-impact analysis. While left temporal and frontal regions showed dissimilarities between the tasks, right-hemispheric parietal regions exhibited similarities. We speculate that this could indicate a homologous function of these regions, potentially sharing less-specific representations between the tasks. We further uncovered a dissociation of the alpha and beta bands regarding the similarity across tasks. While the beta band was dissimilar between word and episodic memory retrieval, the alpha band seemed to contribute to the similarity we observed in right parietal regions. Whether this points to a task-unspecific function of the alpha band or a functional role in the retrieval process of the presumed representations, remains to be determined. In summary, we present an approach to study similarity across tasks using the temporal, spectral, and spatial dimensions of EEG data, and present results of exploring the shared oscillatory fingerprints between episodic memory and word retrieval.

Neural oscillations in the delta (0.5-4 Hz) and theta (4-8 Hz) bands play a key role in tracking the temporal structure of speech. According to Temporal Sampling (TS) theory, dyslexia arises from atypical entrainment of these low-frequency oscillations to speech during infancy and childhood, which is particularly disruptive regarding phonological encoding. However, studies of adults with dyslexia have rarely examined both delta and theta cortical tracking under naturalistic listening conditions, and have not measured delta-band cortical tracking. Using EEG, here we focused on delta and theta band cortical tracking continuous natural speech by adults with and without dyslexia, applying a decoding analysis previously used with dyslexic children. Forty-eight English-speaking adults (24 dyslexic, 24 control) listened to a 16-minute continuous spoken narrative while EEG was recorded. Neural decoding of the speech envelope was quantified using backward multivariate Temporal Response Function (mTRF) models applied at two levels: a between-group analysis evaluating group-level differences in neural representation patterns, and a within-participant analysis assessing individual decoding accuracy. Cerebro-acoustic coherence was computed in parallel to provide a complementary measure of neural-speech synchronisation. Additional analyses examined band power, cross-frequency phase-amplitude coupling (PAC), and cross-frequency phase-phase coupling (PPC). Dyslexic adults exhibited less accurate delta- and theta-band decoding in the between-group analysis and reduced theta-band decoding accuracy in the within-participant analysis, alongside reduced coherence in both bands and increased delta-band power, particularly over the right temporal region. No group differences were found for PAC or PPC. HighlightsO_LIAdults with dyslexia showed reduced delta- and theta-band speech decoding C_LIO_LICerebro-acoustic coherence was reduced in delta and theta bands in dyslexia group C_LIO_LIDelta-band power was increased in dyslexia, especially over right temporal region C_LIO_LICross-frequency coupling did not differ between adults with and without dyslexia C_LI

Mental fatigue is known to impair cognitive and motor performance, but its impact on motor learning remains unclear. This study examined how mental fatigue affects skill acquisition in a sequential finger-tapping task. Twenty-eight participants were assigned to either a mental fatigue group, which completed a thirty-minute Stroop task, or a control group, which watched a documentary of equivalent duration. Both groups then trained on the finger-tapping task across multiple practice blocks with brief rest periods. Overall motor skill improved similarly in both groups. However, mental fatigue altered the pattern of acquisition: participants in the fatigue group showed decreased performance during practice blocks, which was compensated by larger gains during inter-block rest periods. A strong negative correlation was observed between online decrements and offline improvements, indicating that greater declines during practice were associated with larger gains during rest. This study highlights the critical role of rest periods in maintaining learning under cognitively demanding conditions and provides insight into how internal states, such as mental fatigue, can selectively influence the expression of performance without compromising overall learning.