Brain Communications

Background: Aberrant basal ganglia activity is a key feature of the pathophysiology of dystonia, but evidence is predominantly based on adult cohorts. Neurophysiological signatures during development remain poorly characterised. Local field potentials (LFPs) recorded by bidirectional neurostimulators provide a direct measure of globus pallidus internus (GPi) activity. In a cross-sectional paediatric cohort, we investigated whether pallidal oscillatory, aperiodic and connectivity characteristics are associated with dystonia severity and whether these differ between genetic and acquired dystonias. Methods: We recruited 30 children and young adults (5-20 years) with medically refractory dystonia (genetic n = 10; acquired n = 20) who underwent bilateral GPi Deep Brain Stimulation (DBS) implantation. Ten minutes of pallidal LFPs were recorded using Medtronic Percept RC neurostimulators with stimulation off, before DBS activation and, where available, at 12 months. Spectral power, aperiodic exponent and interhemispheric pallidopallidal coherence were quantified across delta (1-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), beta (13-30 Hz), and low-gamma (30-45 Hz) frequency bands. Linear mixed-effects models were implemented to establish whether LFP markers were predictive of dystonia severity, as measured by the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS-Movement). Firths Bias-Reduced Logistic Regression assessed whether LFP markers were predictive of dystonia aetiology. Results: Spectral peaks were most consistently detected in the delta, beta, and low-gamma bands. Delta and low-gamma peak power significantly predicted dystonia severity. This association was independent of medication burden, structural GPi involvement, and dystonia aetiology. Theta and alpha peaks were detected less consistently, and their power was not associated with dystonia severity. Pallidopallidal coherence significantly predicted dystonia severity in interaction with medication load in all frequency bands. Low-gamma peak power was significantly lower in acquired than genetic dystonia, but the potentially confounding influence of dystonia severity could not be excluded. The aperiodic exponent was not associated with severity or aetiology. Conclusion: Pallidal LFP markers are associated with dystonia severity in children, with delta peak power, low-gamma peak power and pallidopallidal coherence reflecting clinically relevant features of disease expression. These findings highlight the potential of pallidal LFPs to characterise dystonia across the lifespan and motivate longitudinal studies of their developmental and clinical trajectories.

Objectives: Seizure freedom follows surgery in 67% of children with drug-resistant epilepsy, but imaging biomarkers could improve patient selection, epileptogenic zone localisation, and outcome prediction. We assessed whether diffusion MRI abnormalities predicted seizure freedom when resected; aligned with stereo-EEG seizure-onset and interictal zones; distinguished patients with/without an identified onset zone; and localised the epileptogenic zone in MRI-negative cases. Methods: We retrospectively studied children undergoing focal resection (n=110) or stereo-EEG (n=61) between 2015-2023, alongside healthy controls aged 6-18 (n=69), using identical 3T MRI diffusion protocols. Age- and sex-adjusted normative models generated mean diffusivity (MD) and fractional anisotropy (FA) voxelwise z-score maps to identify dominant abnormalities. In resection patients, abnormality-resection overlap was related to 12-month or longer Engel outcome. In stereo-EEG patients, z-scores were compared across seizure-onset, interictal, and uninvolved grey-matter contacts. In lesion-negative patients, abnormalities were compared with PET hypometabolism and stereo-EEG findings. Results: Greater resection of MD abnormalities predicted seizure freedom, especially with overlap >0 (mean differences 17%, 23%; Pperm=0.0086, <0.001), and higher odds of Engel I (OR 1.31/10%; AUC 0.723; Youden threshold 36%). FA showed similar associations. Seizure-onset contacts had higher MD and lower FA z-scores than uninvolved grey matter (+0.65, 0.18; Pperm<0.001, =0.001), with interictal contacts intermediate. Abnormalities were more widespread and contralateral in patients without an identified onset zone. In lesion-negative patients, abnormalities co-localised with PET (20/28 fully, 6/28 partially) and stereo-EEG (17/24 fully, 3/24 partially). Interpretation: Diffusion MRI abnormalities aligned with invasive electrophysiology, predicted seizure freedom when resected, and co-localized with PET/stereo-EEG, supporting an important role in presurgical evaluation.

Brain tumors interact with adjacent neural circuits, with tumor infiltration altering neural physiology, and aberrant neuronal activity, in-turn, promoting tumor growth. Due to limited patient numbers, variable recording methods, and tumor heterogeneity, direct evidence of electrophysiologic distinctions between specific tumor types and these interactions in the intact human brain is lacking. Here, we analyzed intraoperative recordings from 100 participants undergoing tumor resection, epilepsy surgery, or movement disorder deep brain stimulator implant surgeries using clinical electrocorticography (ECoG), mesoscale ECoG, and high-density micro-ECoG. Tumor cases included IDH-mutant (IDHm) gliomas across grades, IDH-wildtype (IDHwt) glioblastomas, and metastases. Multiscale neurophysiological activity was spatially mapped to patient-specific tumor and brain anatomy, enabling direct assessment of physiological changes across the tumor-brain interface. Our findings show that population-averaged electrophysiological measures alone provide limited diagnostic separation, whereas spatially-resolved analyses reveal robust physiological gradients linked to tumor distance. Measures of excitatory-inhibitory balance, particularly aperiodic exponent and high-gamma activity, varied systematically with tumor proximity and correlated with local tumor volume fraction around individual electrode contacts. These relationships were detectably different between infiltrative glioma (both IDHwt and IDHm) and metastases, even across recording scales. Furthermore, functional connectivity revealed specific patterns of network organization with the infiltrative glioma cohort, clearly separating IDHwt and IDHm. Beta band coherence between the tumor and brain was significantly reduced in IDHm compared to within the tumor or within brain connectivity (p=0.0006; Kruskal-Wallis test ; mean coherence tumor-brain: 0.26, tumor-tumor: 0.44; brain-brain: 0.34), a pattern not seen in IDHwt or metastases.. Physiological abnormalities extended into radiographically normal-appearing brain. Together, these findings reveal spatially organized, tumor type-dependent physiological signatures of tumor-brain interactions in the intact human brain. Electrophysiology may therefore provide a dynamic physiological map of the tumor-brain interface that complements structural imaging.

Objective: Cortico-cortical evoked potentials (CCEPs) are used during intracranial EEG (iEEG) monitoring to probe effective connectivity and guide epilepsy surgery. However, the factors governing spatial distribution and variability of stimulation-evoked responses across patients remain incompletely understood, making it difficult to distinguish physiological variation from pathological responses. We aimed to develop interpretable models of CCEP responses that integrate normative and patient-specific features, and to assess how these relationships are influenced by distance, brain-state, and epileptogenicity. Methods: We analyzed single-pulse stimulation data from 34 patients with drug-resistant epilepsy undergoing stereo-EEG monitoring. Significant CCEP responses were defined using N1 peak amplitude. For each stimulation-response pair, we derived multimodal features capturing Euclidean distance, effective connectivity priors from F-TRACT, a published population atlas of CCEP response probabilities, normative structural connectivity and communication metrics, and patient-specific functional connectivity estimated from iEEG during baseline and pre-stimulation periods. Lasso-regularized logistic regression models were trained to predict response using leave-one-patient-out cross-validation, and feature importance was examined across spatial scales and seizure onset zone (SOZ) involvement. Results: Performance to predict stimulation-evoked responses improved with the integration of multiple feature domains, with the full model achieving the highest accuracy (median AUC = 0.84). Feature relevance varied with spatial scale: short-range responses were dominated by distance and normative priors, whereas long-range responses depended strongly on patient-specific functional connectivity, especially when measured from pre-stimulation periods. Prediction errors were significantly higher for stimulation-response pairs within the SOZ, indicating deviations from normative connectivity-response relationships in epileptogenic networks. Significance: CCEP responses reflect an interaction between spatial constraints, network architecture, and patient-specific brain state. Multimodal modeling of CCEPs provides a principled framework to interpret stimulation responses and may offer complementary markers for identifying epileptogenic networks during presurgical evaluation.

Background: Software tools can support MRI diagnosis of focal cortical dysplasias (FCDs) - subtle, surgically-treatable lesions that underlie drug-resistant focal epilepsy (DRFE). MELD-graph, a widely used open-source tool combining surface-based morphometry with a convolutional neural network, was developed using 1.5T and 3T MRI data. 7T MRI is increasingly used for lesion detection in DRFE. This study investigated whether MELD-graph is robust to domain shift at 7T. Methods: We collated paired 3T and 7T T1-weighted MRI, and FLAIR where available, from 23 patients with FCD (6 histologically-verified, 17 identified radiologically) and 39 healthy controls at four epilepsy centres. Manual lesion labels were used as ground truth. MELD-graph was run on 3T images, on 7T images with the default pipeline, and on 7T images with adaptations for 7T MRI (SPM bias-field correction, SynthStrip skull-stripping, sub-millimetric FreeSurfer reconstruction), with and without ComBat harmonisation. FCD detection performance and surface morphometry features were compared. Results: Sensitivity for FCD detection was 65% (15/23) at 3T, 48% (11/23) for 7T default and 52% (12/23) for 7T adapted, with Combat harmonisation. Among radiologically 3T-negative patients, 2/8 were detected at 3T and 3/8 at 7T; and among histologically confirmed FCD, 3/6 at 3T and 1/6 at 7T. Specificity was significantly lower at 7T (default 39%, adapted 45%) than 3T (76%). False-positives predominantly occurred in the basal temporal lobes. ComBat harmonisation improved specificity in all conditions and largely compensated for field-strength dependent differences in surface morphometry features. Adding FLAIR at 7T increased false-positive predictions. Conclusion: Sensitivity is comparable but specificity of MELD-graph is lower at 7T compared to 3T. Adaptations for 7T MRI can reduce segmentation errors but do not significantly improve FCD detection, while harmonisation improves performance. The adapted pipeline is released open-source. 7T MELD-graph outputs may inform radiologist review in challenging cases but require cautious interpretation.

Background Chronic subdural hematoma (CSDH) is common and increasing in incidence. Short-term post-surgical outcomes are good, but longer term, patients experience increased morbidity and early mortality than controls and the general population. Deprivation and ethnicity affect many health conditions, but to our knowledge, this is the first UK study investigating their association with CSDH outcomes. Methods This single-centre retrospective cohort study used Secondary Uses Service Admitted Patient Care Spells (SUS+ APCS) data. Adult subdural hematoma (SDH) patients admitted to St Georges Hospital, London treated with burr-hole surgery between April 2022 and April 2025 were included. Primary outcomes were initial length of stay (LoS) and days spent hospitalised in the subsequent year. Deprivation was measured using Index of Multiple Deprivation (IMD). Linear regression models estimated initial LoS and subsequent days spent hospitalised by category, adjusted for factors including age, ethnicity and comorbidities. Results In this single-centre cohort of 449 patients, IMD was not associated with initial LoS, but was significantly associated with subsequent time spent hospitalised. In a log-transformed linear regression model, the most deprived spent 4.5-times longer hospitalised during the year after CSDH than the least deprived (fold change = 4.45, 95% confidence interval (95%CI) 2.20 to 9.01). Conclusions Higher neighbourhood-level deprivation was associated with time spent hospitalised following CSDH. This was robust to adjustment for potential mediating factors. This is the first UK study demonstrating health inequalities in CSDH outcomes, highlighting a need for future research to gain further insights, and to improve equity of outcomes after CSDH.

Background: Dopamine replacement reshapes subthalamic activity in Parkinson's disease, but whether this response reflects anatomically organized network reconfiguration remains unclear. Objectives: To determine whether levodopa preferentially reorganizes dorsal subthalamic spectral activity and cortico-subthalamic directionality. Methods: Twelve participants undergoing bilateral subthalamic deep brain stimulation contributed 30 contacts (14 dorsal, 16 ventral). Recordings obtained OFF and ON medication underwent spectral parameterization and multiband state-space analysis. Simultaneous electroencephalography in six participants enabled assessment of directional cortico-subthalamic coupling using the phase slope index. Results: Levodopa suppressed beta power more strongly dorsally than ventrally (-2.473 versus -0.120 dB; p=0.0438). Dorsal theta power increased, with a trend toward an increase after baseline normalization (p=0.07). Dorsal contacts exhibited greater theta-beta (+5.904 versus +1.610 dB; p=0.006) and gamma-beta (+2.516 versus +0.384 dB; p=0.0188) state-space shifts, principally driven by beta suppression. Gamma changes did not differ regionally. Concurrently, dorsal low-beta and beta interactions shifted toward cortical leading at selected electrodes, whereas ventral responses were less consistent. Conclusions: Levodopa produces a topographically organized subthalamic response, combining preferential dorsal beta suppression with altered cortico-subthalamic directionality. These findings position contact anatomy as a key consideration in characterizing dopaminergic network responses and motivate clinical validation of spatially informed multiband biomarkers for adaptive stimulation.

Disorders of consciousness (DoC) are characterised by marked reductions in cerebral glucose metabolism, but the specific cellular and neurochemical processes driving this impairment remain unclear. To elucidate these mechanisms, a multimodal imaging approach combining [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) and magnetic resonance spectroscopy (MRS) was applied to the posterior medial cortex (PMC) in 15 DoC patients and 14 healthy controls. Regional FDG metabolic index (FDG-MI) values and MRS concentration estimates of glutamate plus glutamine (Glx), {gamma}-aminobutyric acid (GABA+), total N-acetylaspartate (tNAA), total creatine (tCr), and total choline (tCho) were compared between groups and evaluated against Coma Recovery Scale-Revised (CRS-R) scores at baseline and follow-up (mean 127 days). Patients demonstrated reductions within the PMC in Glx, tCr, and tNAA concentrations, as well as a reduced Glx/GABA+ ratio. Local FDG-MI was substantially reduced in patients and correlated positively with tNAA and tCr. Furthermore, baseline tCho concentrations positively predicted long-term clinical recovery, as indexed by changes in CRS-R scores at follow-up. These findings suggest that macroscopic glucose hypometabolism in DoC may be linked to disrupted intracellular mitochondrial energy production pathways and a shift towards relative synaptic inhibition in the PMC. Moreover, the association between choline levels and behavioural recovery may point to the relevance of retained structural synthesis capacity for functional outcomes.

There are known alterations in decision-making attributed to Parkinson's disease. Yet little is known about how those alterations affect decisions in social contexts. We aimed to assess social decision-making in healthy human volunteers as well as people with Parkinson's disease treated with deep brain stimulation of the subthalamic nucleus. Twenty healthy controls and twenty-two people with Parkinson's in both the stimulation ON and OFF conditions took part in a social discounting task that measured the degree of generosity toward others as a function of social-emotional distance. Using a computational approach, we modelled mechanisms of social discounting across three different models that differed in how they mapped choice valuation onto observed decisions. People with Parkinson's less often made generous choices than controls. Across all analyses, we found converging evidence that this effect was attributable to increased static and dynamic decision noise, i.e. inhibitory and attentional processes, but not changes in prosocial valuation. While stimulation sped up decisions, there was no effect of deep brain stimulation on social decision-making. Present results indicate that people with Parkinson's are more prone to random processes such as increased impulsivity and attentional lapses during choices in social situations. Such changes attributed to the disease appear to evade clinical care with dopaminergic compensation and deep brain stimulation.

In aphasia, variability in lesion location and post-stroke network reorganization complicates efforts to identify the regions that support semantic versus phonological processing. In prior work, researchers have often examined these domains in separate patient cohorts, further limiting direct comparison of their neural substrates within aphasia. To address this gap, we investigated the degree of overlap and specialization within semantic and phonological networks in adults with and without aphasia and examined how neural activity relates to task performance and lesion profiles. Sixteen neurologically healthy adults and 15 participants with aphasia following left hemisphere stroke completed adaptive Semantic Matching and Rhyme Judgment tasks during functional near-infrared spectroscopy (fNIRS) recording. Changes in oxyhemoglobin and deoxyhemoglobin were measured within regions of interest, and activation was related to standardized task performance and damage to left ventral and dorsal language pathways in participants with aphasia. Controls showed largely distinct activation patterns consistent with prior fMRI findings: Semantic Matching preferentially recruited ventral stream regions, particularly left temporal cortex, whereas Rhyme Judgment more strongly recruited dorsal regions, including left inferior frontal and inferior parietal cortex. Participants with aphasia showed greater inter-individual variability and no clear group-level segregation of dorsal and ventral activity. Better Semantic Matching performance was associated with less left ventral stream damage and greater left dorsal activation, whereas better Rhyme Judgment performance was associated with lower right hemisphere ventral and dorsal activation. These findings suggest that post-stroke language performance reflects residual specialization, lesion-dependent constraints, and flexible recruitment of surviving tissue. Overall, fNIRS shows promise as an alternative to fMRI for language mapping in post-stroke aphasia, although replication in larger samples with more extensive cortical coverage is warranted.

Background and Objectives Interictal spikes on intraoperative electrocorticography have been used to localize the epileptogenic zone but have limited specificity. We hypothesized that identifying spatially distributed, spike-associated very high-frequency activity (vHFA; 500-2,000 Hz) would improve the ability of spikes to localize the epileptogenic zone. We aimed to characterize spike-associated vHFA and to determine whether a seizure outcome prediction model incorporating vHFA could be externally validated across independent centers. Methods This retrospective two-center cohort study included patients with drug-resistant focal epilepsy who underwent electrocorticography and subsequent resection between January 2016 and May 2025. Spikes occurring across contacts within 50 ms were classified as co-occurring; all others were classified as isolated. We determined whether vHFA was associated with co-occurring spikes. We then assessed whether contacts enriched in vHFA-positive co-occurring spikes were more likely to be located within the resected region among seizure-free patients. Finally, we determined whether the rate of such spikes remaining outside the resection predicted seizure outcomes across the two centers. Results Among 56 patients (mean age: 21.2 years; 26 females), we identified 132,359 spikes, of which 1,925 were vHFA-positive. The vHFA peak preceded the associated spike peak by 8.0 ms (95%CI: 5.0-16.0). vHFA-positive spikes were more likely to be classified as co-occurring, even after adjustment for anatomy and inter-electrode distance (OR: 3.43; 95%CI: 2.82-4.17). Among the 35 seizure-free patients, contacts with higher rates of vHFA-positive co-occurring spikes were more likely to be resected (OR: 11.92 per occurrence/min; 95%CI: 5.62-25.32). This association was stronger than that observed for all spikes (OR: 1.09 per occurrence/min; 95%CI: 1.06-1.11). Twenty patients experienced postoperative seizure recurrence; a higher proportion of vHFA-positive co-occurring spikes in preserved areas was associated with recurrence (OR: 3.22 per 0.01 increase in proportion; 95%CI: 1.14-9.12). In bidirectional cross-center validation, models incorporating vHFA-positive co-occurring spikes yielded areas under the receiver operating characteristic curves of 0.80 and 0.69, with better performance when the model was developed using the larger sample. Discussion Spike-associated vHFA may identify a biologically meaningful subset of interictal spikes involved in propagation across the epileptogenic zone. vHFA-positive co-occurring spikes may represent a generalizable intraoperative biomarker of the epileptogenic zone.

According to the AT(N) framework, Alzheimers disease (AD) can be biologically characterised by amyloid deposition, tau pathology, and neurodegeneration, yet how these processes relate to whole-brain dynamics remains unclear. Here, we investigated these relationships and the link between whole-brain dynamics and cognitive dysfunction using multimodal neuroimaging from 145 ADNI3 participants. We combined multiscale measures of turbulent dynamics with responses to in silico perturbations obtained from whole-brain models. AD progression was characterised by a scale-dependent reorganisation of turbulent dynamics where information flow showed the strongest contribution to the dynamics-related variance in cognitive performance. Large-scale turbulence was associated with all three AT(N) components. Model-based information capability and susceptibility measures progressively decreased across AD stages and were associated with amyloid burden and regional tau deposition. Model-free features discriminated comparisons involving AD dementia, whereas adding model-based measures produced modest, metric-dependent changes in classification performance. Exploratory analyses showed spatial alignment between large-scale turbulence alterations and AD-risk gene-expression gradients, with APOE among the strongest associations in both disease-stage contrasts examined. Lastly, we found a progressive decoupling between turbulent dynamics and the E:I balance across AD stages. Together, these findings link model-based and model-free measures of whole-brain dynamics to proteinopathy, neurodegeneration, and cognitive impairment, supporting their complementary value for characterising AD progression.

White matter hyperintensities on brain magnetic resonance imaging are established markers of cerebral small vessel disease and typically associate inversely with brain volume in the general population, reflecting irreversible tissue loss. In Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy, a monogenic small vessel disease caused by NOTCH3 cysteine-altering mutations, white matter hyperintensities may instead reflect tissue water accumulation and perivascular space dilation rather than net structural damage. Whether this distinct pathophysiological relationship is detectable at population level among carriers of NOTCH3 cysteine-altering variants without clinically manifest disease remains unknown. We conducted a cross-sectional neuroimaging study using UK Biobank data acquired between 2014 and 2023. Among 44,943 participants with complete brain magnetic resonance imaging data (mean age 64 years +/- 8 years), 96 carried heterozygous NOTCH3 cysteine-altering variants within epidermal growth factor-like repeat domains 7 to 34 and 44,847 were non-carriers. White matter hyperintensity volume was automatically quantified and normalized to total intracranial volume. Brain parenchymal fraction was defined as combined gray and white matter volumes divided by total intracranial volume. Lacunes were manually assessed in all carriers. Linear regression and generalized additive models examined the association between white matter hyperintensity volume and brain parenchymal fraction stratified by genotype, adjusting for age, sex, lacune count, and vascular risk factors. NOTCH3 variant carriers showed markedly higher normalized white matter hyperintensity volume than non-carriers (0.83% versus 0.36%; P<10^-8) but only marginally higher brain parenchymal fraction (81.1% versus 80.5%; P=0.03). In non-carriers, white matter hyperintensity volume was inversely associated with brain parenchymal fraction (beta=-0.116% per 1% increase; P=3.10^-6). In contrast, NOTCH3 variant carriers demonstrated a positive association (beta=+0.51%; P=0.019), strengthened after adjusting for lacune count (beta=+0.61%; P=0.006). A significant genotype-specific interaction confirmed this divergence (P=0.036), persisting across age groups and after vascular risk factor adjustment. NOTCH3 cysteine-altering variant carriers identified at population level exhibit a fundamentally distinct white matter hyperintensity-brain volume relationship compared with non-carriers, consistent with lesions reflecting tissue water accumulation rather than irreversible structural loss at this early, predominantly preclinical disease stage. These findings establish that genetic context modifies neuroimaging biomarker interpretation in cerebral small vessel disease and underscore the need for genotype-aware approaches when evaluating white matter hyperintensities as markers of disease severity or progression.

ObjectiveThe current International League Against Epilepsy (ILAE) guidelines for Lennox-Gastaut syndrome (LGS) mandate the presence of generalized paroxysmal fast activity (GPFA) on EEG. However, GPFA is not necessarily restricted to LGS and has been described in, among others, idiopathic generalized epilepsies. A clear definition for GPFA is currently lacking, hampering research into its utility as a diagnostic or treatment biomarker. Here, we assessed expert agreement in the interpretation of GPFA to explore feasibility of a consensus-based definition. MethodsWe internationally distributed a two-part survey on GPFA to EEG experts. First, participants completed thirteen questions gauging their preferred clinical and EEG criteria for GPFA, including duration, frequency, amplitude and topography. Second, participants classified the presence versus absence of GPFA in eleven EEG clips, while blinded to clinical context, from patients with LGS, other epilepsies, and physiological variants. Results162 respondents, predominantly from North America and Europe, completed the survey. 87% considered GPFA to also occur in epilepsies other than LGS. Considerable heterogeneity was present on defining duration, spectral frequency, amplitude and topographic distribution of GPFA. Particularly poor agreement was seen for lower limits of duration and frequency, with no single response option receiving a majority consensus (36% and 30% agreement, respectively). Similarly, the degree of agreement on interpretations was highly variable across real-world EEG clips. SignificanceMarked discrepancies exist in the EEG identification and clinical interpretation of GPFA, undermining its utility as a potential biomarker in research and clinical trials of LGS and other epilepsies. The findings also highlight the need to establish a consensus-based and eventually evidence-informed definition to formally operationalize the clinical and EEG criteria for GPFA. Key pointsO_LIGeneralized paroxysmal fast activity (GPFA) is variably defined in the literature, limiting its utility as a diagnostic or treatment biomarker C_LIO_LIIn this international survey (n = 162 respondents, 25 countries) we found limited agreement on GPFAs defining features and on interpretation of fast activity on EEG clips C_LIO_LI87% of respondents considered GPFA to occur in epilepsies other than Lennox-Gastaut syndrome C_LIO_LIPending further elucidation of the pathophysiology underlying GPFA or its computational characterization (i.e., to inform a biologically-or evidence-based definition), we underscore the need for an interim consensus-based definition C_LI

Over 30% of patients with epilepsy are refractory to medication and may require surgical or neuromodulation-based intervention. Accurate localization of seizure-onset zones (SOZ) and assessment of treatment-associated brain responses remain major clinical challenges. Current workflows may involve invasive intracranial monitoring, prolonged hospitalization, adjustment of anti-seizure medications, and seizure capture to localize the SOZ, while opportunities for complementary intraoperative functional assessment remain limited. We used intraoperative functional ultrasound imaging (fUSI) to characterize interictal (i.e., non-seizure) cortical activity in nine patients with drug-resistant focal epilepsy and to assess treatment-associated brain responses following SOZ resection and responsive neurostimulation (RNS). fUSI signals were acquired directly from the exposed cortex during standard-of-care surgery. We developed six ultrafast power Doppler-based interictal activity markers (IaMs) to distinguish SOZ from peri-resection zone (PRZ) cortex and to quantify treatment-associated changes. The IaMs revealed distinct interictal hemodynamic dynamics between SOZ and PRZ cortex. Following SOZ resection, all six markers changed significantly within the surrounding PRZ. RNS also induced robust, stimulation paradigm-dependent modulation of cortical hemodynamic dynamics. Notably, RNS and surgical resection produced concordant directional changes across five of the six IaMs, despite representing fundamentally different therapeutic interventions. Together, these findings demonstrate the feasibility of intraoperative fUSI for characterizing and distinguishing interictal dynamics within SOZ and PRZ cortex and assessing treatment-associated cortical responses during human epilepsy surgery. Furthermore, fUSI could provide a complementary high-resolution functional imaging approach alongside established clinical methods for SOZ localization and intraoperative functional assessment.

Temporal lobe epilepsy (TLE) is associated with altered functional connectivity, yet its effects on connector hubs, regions supporting long-range and inter-network communication, remain poorly understood. We used SParsity-based Analysis of Reliable k-hubness to characterize connector hub reorganization in unilateral TLE compared with healthy controls. Patients exhibited significant widespread reductions in k-hubness involving the occipital, cingulate, and precuneus regions, ipsilateral hippocampus, and the bilateral pallidum. Compared to the distribution of k-hubness in healthy controls, the hub disruption index revealed rapid loss of k-hubness alongside emergence of new hubs in contralateral homologous regions. To investigate microstructural substrates of these functional changes, apparent diffusion coefficient and fractional anisotropy from diffusion magnetic resonance imaging were examined. The strongest associations with k-hubness were observed in subcortical structures and the hippocampus. These findings demonstrate that TLE is characterized by widespread, asymmetric connector hub reorganization extending beyond the epileptogenic temporal lobe, revealing distinct patterns of network disruption and reorganization across the brain.

Phosphorylated -synuclein at S129 (pS129) is the predominant form of -synuclein in the aggregates known as Lewy bodies (LB) and Lewy neurites (LN), the pathological hallmarks of Parkinson's disease (PD) and dementia with Lewy bodies (DLB), collectively known as synucleinopathies. The toxic nature of these inclusions remains contentious. To improve our understanding of these aggregates and their role in the structural and functional changes observed in synucleinopathies, we combined non-invasive structural and functional MRI in awake head-fixed M83 mice with whole-brain light-sheet fluorescence microscopy (LSFM) in the same animals following a unilateral injection of either human preformed fibrils of -synuclein (PFF) or PBS into the dorsal striatum. We developed a multimodal framework integrating the non-invasive, mesoscopic nature of MRI with the cellular-level details of LSFM to further our understanding of the underlying pathology of synucleinopathies. Using this framework, we show that four months after injection, animals injected with PFFs showed ubiquitous spread of pS129 pathology throughout the whole brain and spinal cord consistent with anatomical connectivity from the seeding region, with some structures such as the midbrain more susceptible to pS129 accumulation. Compared to controls, PFF-injected animals showed widespread atrophy as well as a decrease in functional connectivity, while evoked activity in the somatosensory/somatomotor areas in response to spontaneous paw movements showed significant hypoactivation. These cellular, structural and functional changes were significantly associated with the proportion of pS129 accumulation determined in the same animals. Our results demonstrate the deleterious effects of pS129 accumulation and argue in favor of a toxic role played by these aggregates.

Background and Objective: For their acceptance as endpoints in clinical trials, biomarkers and clinical outcome assessment (COA) measures should show reliability by being reproducible (precise) and responsive to change. We evaluated precision and responsiveness of MRI-derived brain volume metrics and various COAs in ceroid-lipofuscinosis, neuronal-3 (CLN3) disease. Methods: This longitudinal observational study (NCT03307304) included 44 individuals with CLN3-related disease (ages 0.5-29.1 years, 48% female). Brain volumetric measures were computed using SynthSeg-v2.0 from T1-weighted 3D MPRAGE images acquired at 3T (Median [Q1, Q3] total MRI follow-up duration from baseline: 2.04 [0.00, 3.69] years). Compartmental tissue volumes were normalized to a model-adjusted total intracranial volume and scaled to the tissue-specific volume fraction expected in healthy adolescent brains to extract measures of brain atrophy. COAs included the Vineland Adaptive Behavior Scales, verbal IQ, and the Unified Batten Disease Rating Scale (UBDRS). Analysis of linear mixed-effects models included only CLN3 participants with syndromic presentation, having three or more visits per measurement to estimate slope, its relative standard error (RSE), and the minimum inter-visit interval (Tmin) for statistically significant progression for each participant. Tmin to detect progression in 75% of the population (Tmin,75%) was computed for each metric. Results: Among brain volumetric measures, brain parenchyma volume (BPV) and gray matter volume (GMV) were the most precise and responsive metrics. BPV showed an overall intra-individual decline with age of -1.32%/year (95% CI: -1.64% to -0.99%), low RSE of 12.5%, and short Tmin,75% of 0.85 years (95% CI: 0.47-1.24). Amongst COAs, the UBDRS Clinical Global Impression (CGI) score was the most precise and responsive with an overall intra-individual increase of 1.26 units/year (95% CI: 1.03-1.49), RSE of 24.10%, and Tmin,75% of 2.56 years (95% CI: 1.73-3.46), though with lower precision (RSE higher) and lower responsiveness (Tmin,75% longer) than BPV. Discussion: MRI-derived metrics, in particular BPV and GMV, detected change in brain atrophy with high precision and responsiveness suggesting that they would be informative for evaluating potential neuroprotective therapies in CLN3 disease. These findings support incorporating MRI-derived volumetric measurements alongside clinical assessments in future clinical trials in CLN3.

Drug-resistant focal epilepsy (DRFE) is understood as a complex brain network disorder. As a result, conventional pair-wise functional connectivity may fail to capture the higher-order interactions between groups of epileptogenic regions. We applied multivariate information theory to stereotactic electroencephalography-defined networks in retrospective resting-state fMRI analysis to determine whether the overall strength and dominant type of interdependencies between three or more regions, represented by the S-information and O-information respectively, could offer clinically relevant insights prior to surgical intervention in DRFE. We found networks involving the epileptogenic zone to be mostly dominated by re-dundant information-sharing, which was predicted by stronger structural and functional connections between regions. Non-temporal lobe epilepsy patients demonstrated greater redundancy and stronger comparative interdependencies than temporal lobe epilepsy patients, in line with a more complex network architecture. Among non-temporal lobe cases with postoperative follow-up, not seizure-free patients displayed more positive O-information deviation scores than seizure-free patients, suggesting elevated redundancy in networks associated with poorer surgical outcomes. Our findings potentiate the S-information and O-information as complementary higher-order descriptors of the epileptogenic network within personalised presurgical assessments.

Syntax processing impairment is a defining feature of primary progressive aphasia (PPA), particularly in the nonfluent/agrammatic variant. However, current models are derived largely from Indo-European languages, and it remains unclear whether the cognitive and neuroanatomical mechanisms of syntax processing generalize to Chinese, an analytic, pro-drop language that encodes grammatical relationships primarily through word order and function words rather than inflectional morphology. Participants were recruited from the international Chinese Language Assessment in PPA cohort and included 64 individuals with PPA (19 logopenic, 15 nonfluent/agrammatic, 15 semantic, and 15 unclassifiable/mixed) and 60 cognitively healthy controls. Participants completed sentence comprehension and production tasks with systematically manipulated syntactic features. Item-level linguistic determinants were examined using ridge regression, diagnostic performance using receiver operating characteristic analyses, and neuroanatomical correlates using voxel-based morphometry of structural MRI. Performance on sentence comprehension and production was influenced by grammatical and lexical features. Subject-relative clauses, passive constructions, a higher proportion of function words, longer character length, and greater lexical content were associated with poorer performance among participants with PPA. Sentence comprehension was impaired in the logopenic, nonfluent/agrammatic, and semantic variants, even when isolated to the syntactic component of the sentence comprehension task. Similarly, sentence production was impaired across all PPA variants (all P < 0.01 versus controls). No significant differences were observed among PPA variants. Adjusted receiver operating characteristic analyses demonstrated high discrimination between each PPA variant and controls, with areas under the curve ranging from 0.87 to 0.97 for sentence comprehension-syntax and from 0.91 to 0.97 for sentence production. However, pairwise comparisons showed no significant differences in discriminative performance among PPA variants after correction for multiple comparisons. Both sentence comprehension-syntax and sentence production showed associations with semantic and repetition measures in addition to motor speech measures. Voxel-based morphometry showed that higher sentence comprehension-syntax scores were associated with greater grey matter volume in left frontotemporal and cingulate regions, whereas higher sentence production scores were additionally associated with greater gray matter volume in frontostriatal structures, including the caudate, putamen, and thalamus. Syntactic processing impairment in Chinese-speaking individuals with PPA extends beyond the nonfluent/agrammatic variant and is associated with distributed frontotemporal and frontostriatal regions, as well as lexical-semantic and auditory verbal short term memory mechanisms. These findings suggest that the cognitive and neural manifestations of syntactic impairment may be shaped by language-specific typological properties, underscoring the need for linguistically informed approaches to the assessment and interpretation of PPA.