Healthy aging is accompanied by subtle difficulties in language production. While behavioral and neuroimaging studies suggest that older adults rely on acute semantic access to maintain language abilities, the underlying neurophysiological mechanisms remain poorly understood. In particular, it is still unclear how large-scale brain dynamics reorganize to support naturalistic sentence generation with age. In this study, we investigated the spatiotemporal brain-state dynamics during covert sentence generation (GE2REC protocol) in younger and older adults using magnetoencephalography (MEG). Source-reconstructed MEG signals were analyzed using a Hidden Markov Model which identified five recurrent brain states, encompassing language-semantic, language-control, sensorimotor, and visual domains. Latent modeling was then used to relate the spectral and temporal properties of these brain states to age and language performance. Spectrally, older adults appear to redistribute oscillatory activity from sensorimotor-related states toward semantic-related states across alpha, beta, and low-gamma frequency bands. Temporally, older adults exhibit a more segmented processing sequence between semantic and sensorimotor processing which interfaces with visuo-posterior processing. These changes robustly covaried with age and better verbal fluency (semantic and lexical). Taken together, these results suggest that the older adult brain undergoes a coordinated time-frequency reorganization to support sentence production. Older individuals likely establish an embodied semantic strategy that involves a more segmented processing sequence during sentence production via visuo-posterior information processing. We speculate that this may help shape a resource-efficient, predictive route for complex cognition in older adulthood.

Understanding how the older adult brain sustains cognitive flexibility remains a central question in aging research. Here, we analyzed resting-state fMRI data from the population-based CamCAN database (N = 628; age 18-88) and applied structural balance theory to measure functional network energy, a graph-theoretical proxy of network flexibility. In line with the SENECA model, our findings highlight midlife as a critical transition period: network energy is redistributed along the sensory-transmodal hierarchy, shifting from higher-level networks (DMN-FPN) to lower-level networks (SMN, CON, Auditory, Visual, Language). This reorganization (i) helps preserve the global wiring economy across the lifespan, hinting at an allostatic mechanism (i.e., stability through change) regulated by anti-correlated dynamics; and (ii) may support embodied semantic strategies in older adulthood, leveraging more predictive processing to sustain cognitive flexibility at lower costs. Taken together, our study reframes healthy neurocognitive aging as an allostatic process and provides a reference for extending the SENECA model to metabolism and neuropathology.

In this study, we aimed to identify structural biomarkers linked to the severity and outcome of aphasia after a left-hemispheric stroke. We recruited 72 individuals with post-stroke aphasia and assessed their initial aphasia severity using the Aphasia Severity Rating Scale, alongside measures of naming ability and executive function. Aphasia outcome was determined for 56 out of 72 participants with available Aphasia Severity Rating Scale scores at discharge. We performed support-vector regression symptom mapping analyses at both cortical and white matter levels to examine the relationship between structural brain damage and our variables of interest (initial aphasia severity, naming, executive functions, and aphasia outcome). Our results revealed that (a) disconnections in white matter tracts within ventral and dorsal language pathways were associated with aphasia severity and naming deficits initially; and (b) disconnections in white matter tracts within executive networks (i.e., fronto-parietal, executive control, and salience networks) were related to executive dysfunction. This retrospective cohort study highlighted the crucial roles of white matter tracts within both dorsal (i.e., arcuate fasciculus, superior longitudinal fasciculus) and ventral (uncinate, inferior longitudinal, and middle longitudinal fasciculi) language streams in shaping the cognitive phenotypes of post-stroke aphasia patients, particularly concerning aphasia severity and naming impairment, by delineating distinct patterns of affected brain structures.

Network neuroscience has significantly advanced our understanding of how structural and functional connectivity evolve during healthy neurocognitive aging. Yet, integrative studies linking structural and functional brain organization with cognitive performance remain relatively limited. In this study, we analyzed resting-state functional MRI and diffusion-weighted imaging data from 597 healthy adults aged 18 to 88, drawn from the CamCAN dataset. Using a graph signal processing framework, we investigated how structural connectivity constrains functional brain signals across the adult lifespan. Our results reveal that control and semantic cognitive systems exhibit distinct age-related patterns of structure-function reorganization, potentially reflecting a shift in integrative processing during midlife. Notably, our findings suggest that structurally-coupled sensorimotor integration plays a crucial role for regulating these systems. Until midlife, it accompanies structurally-decoupled activity in transmodal cortices to sustain cognitive control. In parallel, it likely supports the formation of embodied internal models that leverage more structurally-decoupled semantic processes, thus contributing to maintain lexical production skills for longer in older adulthood. Taken together, our study offer new multimodal insights into how sensory-driven processes help reconfigure the healthy aging brain to support controlled semantic cognition.

This study aimed to offer a depiction and comprehensive understanding of school participation in autistic youth, which has received limited exploration. Parents of 871 autistic youth aged 7 or 15 were invited to participate in a study, among whom 600 agreed, allowing data collection on diagnosis, comorbidities, school, professional support, and parental characteristics. They were asked to fill in questionnaires assessing executive functions, social-communication difficulties, and school participation, completed by 241. Structural equation modeling and descriptive methods were employed to examine factors influencing school participation and the desire for change. Social-communication abilities stand out as the sole intrinsic determinant associated with school participation. Being a female and having an intellectual disability might negatively impact mainstream school attendance, without exerting a similar influence on activity attendance and involvement. Caregivers identified school demands and the sensory environment as extrinsic barriers to school participation, while teachers' attitudes and peer relationships were seen as both potential barriers and facilitators. Finally, 36%-58% indicated a desire for increased participation in at least one school activity. Our findings highlight the need to reduce stigma around autism, improve school support, and give special consideration to the schooling experiences of autistic girls.Lay AbstractSchool participation factors in autism have received limited attention. We examined this question using structural equation modeling and descriptive methods. Our findings indicate that heightened social-communication difficulties, rather than executive dysfunctions and comorbidities, are associated with decreased school participation of autistic youths. Furthermore, exploratory analyses showed that being female and having an intellectual disability negatively affect attending mainstream school for autistic children and teenagers, but not their attendance and involvement in school activities. Caregivers point out school demands, sensory environment, and teachers' and peers' attitudes as major factors affecting participation, often expressing a desire for increased participation for their child. These results hold significant implications for improving educational environments for autistic girls and boys.

ABSTRACT Transcranial photobiomodulation (PBM) is an emerging non-invasive brain stimulation method that is thought to increase neural metabolism by stimulating ATP production by the mitochondria. However, the mechanisms of action and the effects on the human brain are still unclear. In the present study, we investigated the potential of this method to enhance Blood Oxygen Level Dependent (BOLD) responses during the execution of a motor task in young and aged participants. Sixty young and aged participants were included in this single-blinded, sham-controlled, randomised, crossover study. They underwent an fMRI recording before and after 24-min stimulation with a 80-LEDs helmet emitting transcranially red and near infrared light. Post vs Pre BOLD signal was compared between PBM and SHAM, in each group. At baseline, aged participants showed reduced BOLD signal compared to young ones, in key regions of the sensorimotor processing, principally the left primary motor cortex and striatum. Transcranial PBM did not have a real impact in the young group. In aged participants, analysis performed on the whole brain did not reveal widespread changes, but rather local increases in BOLD responses in the right ventral premotor cortex and insula. More specifically, a regional analysis further showed increased BOLD responses in the left primary motor cortex, and right dorsal and ventral premotor regions and striatum. Some of these regions were under-activated at baseline in aged participants relatively to the young ones. These results suggest that transcranial PBM can increase fMRI BOLD responses locally in some task-related regions, particularly in aged subjects. Further research are needed to distinguish neural from vascular effects in transcranial PBM.

Computer-based therapy has shown promise in speech rehabilitation for individuals with language disorders. In this study, we investigated behavioural, acoustic and brain network changes in a patient with chronic non-fluent aphasia who underwent an enriched rehabilitation programme, combining the Ultraspeech-player software with conventional speech therapy, followed by a period of conventional therapy alone. The software provided visualisation of articulatory movements recorded from a reference speaker. Comprehensive assessments, conducted before and after each rehabilitation period, included perceptual and acoustic analyses of speech production and brain network measures. Data were compared with normative values from healthy older participants (N = 16). Results showed (i) changes in articulatory configuration after enriched rehabilitation, with partial maintenance after conventional therapy; and (ii) normalisation of right intra-hemispheric functional connectivity and restoration of the integration-segregation balance. This study provides a multimodal characterisation of recovery-related changes, showing how articulatory control and large-scale network organisation may reorganise following rehabilitation.

Aging is accompanied by changes in brain architecture that alter the lateralization of functional networks. In this study, we examined how hemispheric specialization changes across the adult lifespan by analyzing resting-state fMRI and structural MRI data from 728 typical adults aged 18 to 88 years. Using the Language-and-Memory Network atlas, we quantified regional asymmetries in functional connectivity along the cortex's principal gradient, and normalized regional volumes across 37 bilateral regions. We identified two distinct age-related asymmetry trajectories: one pattern revealed a bilateralization of language-dominant regions, while the other showed increasing leftward specialization in multimodal regions associated with memory and language. These opposing patterns emerged around midlife and were linked to performance in language production tasks. By integrating connectivity gradients, structural asymmetries, and behavioral data, our findings provide new evidence for a dual mechanism reshaping functional brain lateralization with age and demonstrate the utility of resting-state metrics in tracking these shifts.

Previous studies concluded that theory of mind (ToM) development is deviant in autism spectrum disorders (ASD). Typically developing children's ability to understand that one may hide their emotion would be acquired before false belief understanding in children with ASD (e.g., Peterson and Wellman 2019), but with contradictory results (e.g., Zhang et al. 2016). In the current work, we aim to determine whether the order of acquisition of ToM-related concepts in ASD differs, using methodological improvements compared to previous studies. Our results support the conclusion of a non-deviant developmental trajectory for ToM in individuals with ASD, with a general ability to understand hidden emotions that is not mastered before false belief attribution.

Lexical production performances have been associated with cognitive control demands increase with age to support efficient semantic access, thus suggesting an interplay between a domain-general and a language-specific component. Current neurocognitive models suggest the Default Mode Network (DMN) and Fronto-Parietal Network (FPN) connectivity may drive this interplay, impacting the trajectory of production performance with a pivotal shift around midlife. However, the corresponding time-varying architecture still needs clarification. Here, we leveraged MEG resting-state data from healthy adults aged 18-88 years from a CamCAN population-based sample. We found that DMN-FPN dynamics shift from anterior-ventral to posterior-dorsal states until midlife to mitigate word-finding challenges, concurrent with heightened alpha-band oscillations. Specifically, sensorimotor integration along this posterior path could facilitate cross-talk with lower-level circuitry as dynamic information flow with more anterior, higher-order cognitive states gets compromised. This suggests a bottom-up, exploitation-based form of cognitive control in the aging brain, highlighting the interplay between abstraction, control, and perceptive-motor systems in preserving lexical production.

Hemispherotomy, a neurosurgical procedure that functionally disconnects the affected hemisphere, is the recommended curative treatment for Rasmussen's encephalitis. Following a typically normal developmental period, individuals with Rasmussen's encephalitis develop progressive hemispheric dysfunction and severe epilepsy, ultimately resulting in exclusive "mono-hemispheric" functioning after hemispherotomy. The aim of this study was to provide an in-depth assessment of long-term cognitive outcomes in Rasmussen's encephalitis patients, several years after hemispherotomy. Eighteen patients with Rasmussen's encephalitis (11 on the left hemisphere) underwent extensive cognitive assessment on average more than 14 years after surgery, using a battery of tasks evaluating language, memory, executive functions, and social cognition. The cognitive scores were compared to those of 175 healthy control participants. In addition, graph-based network analyses were conducted on cognitive scores to examine the organization and interactions within the cognitive system. In this extreme mono-hemispheric condition, the entire cognitive network is reorganized. While hemispherotomy maintains a subnormal intellectual efficiency, some functions, such as semantics, memory, and inhibition, tend to be relatively preserved, whereas working memory, syntax, and theory of mind remain impaired in the long term. In the intact hemisphere, strengthened interactions between cognitive functions were observed, especially among patients with a shorter duration of epilepsy before surgery and favorable cognitive recovery. Adopting a network-based perspective on cognition in this clinical context provides novel insights into how cognitive organization and reorganization occur under conditions of profound neuroplasticity.

Cognitive flexibility in the human brain engages dynamic interactions between the Default Mode Network (DMN) and the Fronto-Parietal Network (FPN), a functional architecture that is metabolically demanding and thus potentially susceptible to age-related decline. How the aging brain reorganizes its functional architecture to sustain cognitive flexibility under metabolic constraints remains an open question. In this study, we modeled resting-state functional flexibility across the adult lifespan (ages 18–88) using structural balance theory. Our findings align with the predictions of the SENECA model ( Synergistic, Economical, Nonlinear, Emergent, Cognitive Aging ), revealing a midlife neurocognitive transition: (i) from a metabolically costly, flexible DMN-FPN architecture, toward (ii) a more redundant configuration dominated by low-cost, sensory-driven interactions. The medio-parietal DMN and the Cingulo-Opercular Network (CON) are crucial to this transition, contributing to maintain global brain activity near a critical dynamic regime in older adulthood that optimizes for cognitive flexibility in face of declining metabolic resources. These findings advance a theoretical and methodological framework for understanding neurocognitive flexibility in aging and underscore the importance of multimodal fMRI-PET studies in midlife. They also open promising avenues for translational applications in neuropathology. ![Figure][1] ### Competing Interest Statement The authors have declared no competing interest. Agence Nationale de la Recherche, https://ror.org/00rbzpz17, ANR-15-IDEX-02, ANR-19-P3IA-0003 Biotechnology and Biological Sciences Research Council, BB/H008217/1 [1]: pending:yes

OBJECTIVE:Rasmussen's encephalitis (RE) affects the structure and function of one cerebral hemisphere, typically during childhood. Hemispherotomy is a surgical treatment that functionally disconnects the affected hemisphere. The cognitive consequences of surgery and the potential for postoperative recovery remain poorly understood, however, due to their complex and multifactorial nature. This study aimed to examine the long-term cognitive outcomes of patients with RE following hemispherotomy and identify the clinical factors influencing recovery. METHODS:Forty-four patients who underwent childhood hemispherotomy for RE (28 girls, 23 with left RE) were included in this retrospective study. Neuropsychological assessments were conducted during postoperative follow-up, and verbal (VIQ) and nonverbal (performance IQ [PIQ]) IQ scores from the most recent evaluation were analyzed. The impact of age at seizure onset (ASO), age at hemispherotomy, preoperative epilepsy duration, side of hemispherotomy, age at neuropsychological evaluation, and postoperative follow-up duration on intellectual efficiency scores was assessed using partial least squares analysis. RESULTS:The mean ASO was 5.9 years, the mean age at hemispherotomy was 9.6 years, the mean epilepsy duration was 3.7 years, and the mean postoperative follow-up duration was 9.5 years. After hemispherotomy, 91% of patients were seizure free (Engel class I), and 86% were no longer receiving antiepileptic medication. Patients who underwent hemispherotomy of the language-dominant hemisphere (Hdom) had lower VIQ scores but higher PIQ scores compared to those with hemispherotomy of the nondominant hemisphere (Hnondom). Results showed that higher VIQ was significantly associated with several clinical factors, including a shorter epilepsy duration before surgery, a younger age at surgery, and hemispherotomy of the nondominant hemisphere for language. In contrast, no clear link was found between clinical variables and PIQ. CONCLUSIONS:In RE, early hemispherotomy performed soon after disease onset appears to be associated with better long-term intellectual outcomes. Verbal functions can be recovered following hemispherotomy of the dominant hemisphere, highlighting the preferential reorganization of language in postoperative cognitive recovery. These findings underscore the critical importance of early surgical decision-making in optimizing patient care and maximizing postoperative recovery.

The advancements in understanding hemispheric specialization of language (HSL) have been following two primary avenues: the development of neuroimaging techniques and the study of its reorganizations in patients with various neuropathologic conditions. Hence, the objectives of this chapter are twofold. First, to provide an overview of the key neuroimaging techniques employed to investigate HSL, along with the notable findings derived from them in the healthy population. Second, it focuses on the reorganization of HSL in physiologic (healthy aging) and pathologic (poststroke aphasia and temporal lobe epilepsy) conditions. The chapter emphasizes the importance of employing multimodal methodologies to comprehend the complex relationship between underlying HSL mechanisms affected by disease and resulting language impairments. Combining the neuroimaging techniques can help us understand how different characteristics of language networks combine into general mechanisms that support their plasticity. Nevertheless, it highlights the need for standardized HSL metrics, as the absence of such metrics poses challenges in synthesizing findings across studies. Additionally, while HSL findings are being accumulated, albeit multimodal, there is a lack of integration within a robust theoretical framework. In conclusion, there is a need for novel models acknowledging multimodal aspects of HSL while positioning it within the context of other cognitive functions.

Rasmussen’s encephalitis (RE) is a rare neurological disorder affecting a single cerebral hemisphere, often requiring hemispherotomy as a curative treatment. While significant brain plasticity occurs due to the pathology and surgical intervention, the mechanisms underlying cognitive functioning in the remaining hemisphere remain poorly understood. This multiple-case study longitudinally investigates neurocognitive reorganization in childhood after left hemispherotomy for RE and identifies structural patterns in the right hemisphere associated with language recovery. Indeed, the mechanisms that allow the right hemisphere to support language, after left hemispherotomy remain unclear. Cognitive trajectories were analyzed in three RE patients, and their cortical thickness (CT) changes were compared with data from a publicly available cohort of 393 healthy subjects. Language neuropsychological scores and T1-weighted MRI data were assessed in the healthy right hemisphere before hemispherotomy, one year, and five years post-surgery. Specifically, principal component analysis, structural covariance, and graph theory approaches were employed to investigate language network organization in patients and controls. Results reveal diverse language recovery trajectories among the three patients. Regarding CT, three potential signatures associated with favorable language outcomes were identified: (1) normal or below-normal CT values in cortical regions; (2) a more associative and integrative organization of the language network; and (3) increased global efficiency. These preliminary longitudinal findings provide novel insights into the mechanisms of neurocognitive reorganization following left hemispherotomy in childhood. By emphasizing structural patterns linked to favorable postoperative language recovery, this study highlights their value for guiding future research and clinical interventions.

Autistic individuals often present difficulties in flexibly adjusting their behavior, yet laboratory experiments have yielded inconsistent results, potentially due to various influencing factors requiring precise examination. This study aimed to investigate the hypothesis that the social content of stimuli could play a specific role in some of the flexibility challenges faced by autistic individuals. We analyzed data from 256 adult participants (124 with autism), matched in age, gender, and sex, who performed an emotional shifting task involving unpredictable shifts between positive and negative stimuli. In addition, the task had a social and a non-social condition. Our results revealed a larger switch cost in the social compared to the non-social condition, which was more pronounced in autism compared to non-autistic individuals. Expanding upon previous research demonstrating a greater switch cost in autistic than non-autistic individuals for socio-emotional stimuli, our study further extends these findings by highlighting that the social context, rather than the emotional nature of the stimuli alone, could play a particular role in some of the flexibility challenges faced by autistic individuals. Nevertheless, further studies are needed to investigate if these results also apply to autistic children or autistic individuals who also have intellectual disabilities.

The evaluation of cognitive functions interactions has become increasingly implemented in the cognition exploration. In the present study, we propose to examine the organization of the cognitive network in healthy participants through the analysis of behavioral performances in several cognitive domains. Specifically, we aim to explore cognitive interactions profiles, in terms of cognitive network, and as a function of participants’ handedness. To this end, we proposed several behavioral tasks evaluating language, memory, executive functions, and social cognition performances in 175 young healthy right-handed and left-handed participants and we analyzed cognitive scores, from a network perspective, using graph theory. Our results highlight the existence of intricate interactions between cognitive functions both within and beyond the same cognitive domain. Language functions are interrelated with executive functions and memory in healthy cognitive functioning and assume a central role in the cognitive network. Interestingly, for similar high performance, our findings unveiled differential organizations within the cognitive network between right-handed and left-handed participants, with variations observed both at a global and nodal level. This original integrative network approach to the study of cognition provides new insights into cognitive interactions and modulations. It allows a more global understanding and consideration of cognitive functioning, from which complex behaviors emerge.

As people age, there is a natural decline in cognitive functioning and brain structure. However, the relationship between brain function and cognition in older adults is neither straightforward nor uniform. Instead, it is complex, influenced by multiple factors, and can vary considerably from one person to another. Reserve, compensation, and maintenance mechanisms may help explain why some older adults can maintain high levels of performance while others struggle. These mechanisms are often studied concerning memory and executive functions that are particularly sensitive to the effects of aging. However, language abilities can also be affected by age, with changes in production fluency. The impact of brain changes on language abilities needs to be further investigated to understand the dynamics and patterns of aging, especially successful aging. We previously modeled several compensatory profiles of language production and lexical access/retrieval in aging within the Lexical Access and Retrieval in Aging (LARA) model. In the present paper, we propose an extended version of the LARA model, called LARA-Connectivity (LARA-C), incorporating recent evidence on brain connectivity. Finally, we discuss factors that may influence the strategies implemented with aging. The LARA-C model can serve as a framework to understand individual performance and open avenues for possible personalized interventions. This article explores the complex pathways and cognitive strategies that influence language abilities in aging, using the Lexical Access and Retrieval in Aging with Connectivity (LARA-C) model. We describe insights gained into the diverse language-related aging experiences. Our proposal, supported by literature and data, underscores factors and tailored approaches to promote cognitive health among aging populations.