The influence of Mars’ continental-scale topographic structures on its hemispheric asymmetry in baroclinic wave activity

Sex-specific interhemispheric brain oscillation asymmetries in an ADHD rat model.

Hemispheric asymmetry of the ipsilateral silent period following voluntary movement of the opposite hand.

Disrupted brain network topology and structural-functional decoupling in chronic post-stroke aphasia.

BackgroundCerebrovascular disease (CVD) is a leading cause of mortality with a strong link to cognitive impairment and dementia. White matter lesions (WML) are prevalent in CVD and are early markers of vascular compromise, particularly in relation to intraplaque hemorrhage (IPH), an indicator of carotid artery plaque instability. As vascular disease represents a possible treatment window for dementia subjects, this study explores the relationship between hemispheric WML asymmetry and IPH utilizing a large multicenter cohort to find novel biomarkers of disease.MethodFLAIR MRI scans of 264 subjects from the Canadian Atherosclerosis Imaging Network were categorized as IPH positive (IPH+) or IPH negative (IPH‐) and WML biomarkers were automatically computed (Figure 1). Biomarkers related to WML prevalence (volume) and WML ischemia and progression (intensity) were extracted: ICV‐normalized WML volume (WML‐ICV), WML mean intensity (WML‐Intensity), and WML intensity ratio (WML‐IR). WML asymmetry was assessed via an asymmetry index measure (AIM). Linear mixed models and regression analyses were conducted, with adjustments for age, sex, scanner manufacturer, and stenosis, to evaluate associations between WML biomarkers and IPH status.ResultIPH+ patients exhibited significant rightward asymmetry in WML‐ICV (0.0032 ± 0.002, p < 0.05), WML‐Intensity (7.26 ± 5.41, p < 0.05), and WML‐IR (0.0271 ± 0.0204, p < 0.05); Table 1. IPH+ subjects (left, right or bilateral) had more lesions that were brighter in the right hemisphere. This trend was most pronounced in younger male patients (<65 years), suggesting a high‐risk demographic. Regression analysis revealed IPH as a significant predictor of WML asymmetry, with stronger effects observed in subjects with IPH in the right carotid artery.ConclusionPrevious studies suggest more injury in the right hemisphere for subjects with small vessel disease, and this work supports this finding. With rightward WML asymmetry being strongly associated with IPH, this could be reflecting a surrogate marker for overall vascular disease and its contribution to brain health and dementia. Automated WML biomarkers can be used to identify these high‐risk patients and guide early interventions for subjects with vascular disease and dementia. Future work should validate these findings in larger, longitudinal datasets to enhance clinical applications.

The transmission of pain signals through the spinal cord can cause structural and functional changes in the brain, which may contribute to diverse symptoms. Since the early 19th century, researchers have been studying hemispheric asymmetries in the brain and their effects across different species. However, it remains unclear whether pain-related emotional and cognitive changes are differently affected by left- and right-sided pain. To address this question, we conducted a study comparing the performance of chronic neuropathic mice with left or right spared nerve injury (SNI) in various behavioral tests. We evaluated their behaviors in the open field (OF), Y-maze, novel object recognition, and fear conditioning tests, and compared their performance to that of sham mice. Compared with sham mice, SNI mice manifested mechanical allodynia. In the OF test, SNI-L mice showed an increased anxiety-like profile compared to the other groups. Both left- and right- sided SNI mice showed cognitive deficits to a similar degree in memory tasks. Our results revealed that unilateral chronic neuropathic pain differentially affected anxiety condition, but not pain threshold and cognitive function.

Abstract This study, using the peak electron density of Ionospheric F‐region from the Global‐scale Observations of the Limb and Disk reports, for the first time, a unique phenomenon: the rapid reversal of the intensity of the Equatorial Ionization Anomaly (EIA) crests between the hemispheres during the main phase of 23 April 2023, geomagnetic storm. The Prompt Penetration Electric Field amplified the intensity of both EIA crests. However, the enhancement at the southern crest began to decay within an hour, while the northern crest began to strengthen. Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model simulations indicate that trans‐equatorial wind played a key role in these variations. Wavelet periodograms of ground‐based Total Electron Content measurements confirmed the presence of Traveling Ionospheric Disturbances (TIDs). Storm‐induced winds and TIDs likely changed the altitude of the F‐peaks and the recombination rates between crests, and plasma transport by trans‐equatorial winds also contributed to this rare phenomenon.

Hemispheric specialization in mental arithmetic: Insights from functional transcranial Doppler Sonography.

Maximal tumor resection with neurological preservation is central to brain tumor surgery. This study evaluates the integration of an artificial intelligence-based connectomics platform for surgical planning, with exploratory tractometry analysis of postoperative white matter changes. We retrospectively reviewed 192 consecutive brain tumor surgeries performed between April 2023 and April 2025 using preoperative connectomic mapping (Quicktome, Omniscient Neurotechnology). Functional outcomes were assessed with Karnofsky Performance Status (KPS). In an opportunistic subgroup (n = 13), paired pre- and postoperative imaging enabled tractometry (Cleartome). Fractional anisotropy (FA) was measured across six major tracts, and three hemispheric FA asymmetry indices were calculated: difference in average FA (Diff FA), asymmetry index (AI), and percentage asymmetry (%Asym). The cohort included intra-axial and extra-axial tumors. Median KPS remained stable at 3 months after surgery. In the tractometry subgroup, 12 of 13 patients showed postoperative shifts toward improved interhemispheric FA symmetry in at least one tract. Left-hemisphere cases most often showed changes in the uncinate fasciculus (UF) and inferior fronto-occipital fasciculi (IFOF) (median AI = - 0.68 and - 0.20, respectively), while right-hemisphere cases demonstrated alterations in the superior longitudinal fasciculus (SLF) (median AI = + 5.13; %Asym =-8.43). The corticospinal tract (CST) and IFOF improved in 61.5% of analyzed cases. Tract-based asymmetry indices captured subtle connectivity changes not evident in raw FA values alone. Routine clinical use of AI-guided connectomics in brain tumor surgery was feasible, with stable short-term functional outcomes. Tract-based hemispheric FA asymmetry metrics suggested postoperative microstructural alterations; findings remain preliminary and warrant further prospective validation.

Aim Hemispheric asymmetry is well established in tactile processing, with higher cortical responses observed on the contralateral side of the stimulation area. However, the effect of the interstimulus interval on lateralization is poorly understood. In this context, we aimed to reveal the effects of repeated non-painful tactile stimuli on brain responses and hemispheric lateralization via static ISIs. Methods Twenty-six healthy participants (13 females; mean age 22.2 ± 3.30 years) participated in the study. Tactile stimuli were delivered to the index fingertip of the right hand via a pneumatic stimulator with static ISIs (2s, 4s, and 8s applied as separate sessions). Electroencephalography was performed throughout the procedure. We determined the ROI and primarily analysed nine electrodes (Fz, Cz, Pz, F3, C3, P3, F4, C4, and P4). We measured the peak-to-peak maximum amplitudes (PPmaxN2P3) between N200 and P300, labelling N200 as N2 and P300 as P3. Results The results revealed no significant differences in the amplitudes of PPmaxN2P3 between the ipsilateral and contralateral hemispheres. Constant ISI manipulation altered the laterality of non-painful tactile stimuli. Furthermore, the amplitude of the brain responses would be higher in both the ipsilateral and contralateral hemispheres when the ISI increased. The evaluation of the duration of PPmaxN2P3 was prolonged in the frontal, central, and parietal areas. Conclusion The results indicate that manipulation of the interstimulus interval (ISI) can potentially negate the traditional contralateral advantage observed in tactile processing.

ObjectiveTo establish the first AI-based, population-specific reference standards for brain structural volumes in healthy Chinese children and adolescents, and to elucidate unique developmental trajectories that may differ from existing Western norms.MethodsIn this cross-sectional study, 1,100 healthy participants aged 6–18 years were enrolled. T1-weighted images were acquired using a 3.0T MRI scanner, and regional brain volumes were quantified using an AI-based automated segmentation tool. Multiple comparisons were corrected using the false discovery rate (FDR) method. Differences in brain volume by sex, age, and hemisphere, as well as correlations with age, were analyzed.ResultsAfter controlling for age, males exhibited larger total intracranial volume (P < 0.001) and left cerebral white matter volume (P = 0.015), whereas females showed larger volumes in the bilateral parahippocampal gyri (left: P = 0.023; right: P = 0.011) and left fusiform gyrus (P = 0.026). Significant hemispheric asymmetries were observed in multiple regions. Cerebrospinal fluid (CSF) and bilateral white matter volumes were positively correlated with age (P < 0.001), while volumes in certain frontal and temporal lobe regions, as well as subcortical structures, were negatively correlated with age (P < 0.05).ConclusionThis study is the first to establish reference values for brain volume in healthy Chinese children and adolescents aged 6–18 years using AI-based automated segmentation. It reveals sex- and age-related differences in brain structural development, thereby providing a valuable quantitative reference for future research on brain development deviations. These population-specific standards may provide a theoretical foundation for improving diagnostic accuracy in Chinese children, though their actual utility in reducing misclassification requires future empirical validation.

MRI morphometry tracks disease progression by measuring volumetric changes in brain structures, but it could miss subtle microstructural alterations. Textural changes have been shown to detect these microstructural changes and quantify gray-level spatial patterns more sensitively than volumetry. Similar approaches have detected early hippocampal changes in Alzheimer's disease, suggesting textural analysis could uncover clinically relevant biomarkers in other disorders. In this work, we analyzed 25 participants with cocaine use disorder undergoing repetitive transcranial magnetic stimulation (rTMS) from the SUDMEX-TMS dataset, comparing amygdala volumetric and textural changes over time. Given the amygdala's established role in addiction, we hypothesized that textural features would provide greater sensitivity to rTMS-induced changes than volumetry alone. Feature selection for left and right amygdala was performed using manual selection and LASSO regression with subject-level cross-validation, followed by variance inflation factor (VIF) correction and linear mixed-effects model (LMEM) analysis. The left amygdala model retained 8 of 14 features (4 after VIF correction), achieving an ICC of 0.74, while the right model retained 6 features (4 after VIF correction) with an ICC of 0.59, indicating hemispheric asymmetry in structural stability. Temporal sensitivity analysis revealed that VIF-corrected features showed 2-8 folds higher temporal sensitivity than volume. Five features were shared across hemispheres (Jaccard similarity = 0.56), suggesting partially bilateral but lateralized microstructural determinants of amygdala volume. These GLCM-derived texture features represent potential markers for rTMS response in CUD. Future studies will investigate the mapping of these features to underlying neuropathology.

PurposeTo apply free water elimination (FWE) tractometry to a real-world clinical imaging dataset to quantify pathology-specific patterns of white matter involvement and peritumoral tissue alterations in diffuse gliomas.MethodsThe University of California San Francisco Preoperative Diffuse Glioma MRI dataset was analyzed using FWE tractometry. Twenty major white matter tracts were reconstructed and each divided into 100 equidistant nodes. Direct tumor involvement was quantified across enhancing tumor, necrotic core, and edema regions. Remote white matter tissue properties were assessed through hemispheric asymmetry analysis of free water-corrected fractional anisotropy (FW-FA), mean diffusivity (FW-MD), and free water fraction (FWF) in non-tumor involved regions at standardized distances from radiological tumor margins.Results459 patients with unilateral glioma were included (361 glioblastoma, 87 astrocytoma, 11 oligodendroglioma). Glioblastoma demonstrated greater direct white matter involvement in enhancing tumor and necrotic core compared to astrocytoma and oligodendroglioma (q < 0.001, q = 0.01, respectively). Beyond radiological tumor margins, glioblastoma and astrocytoma exhibited decreased FW-FA, while oligodendroglioma showed increased FW-FA (q = 0.008, q = 0.04, respectively). Distance-based analysis revealed that this effect was most prominent in the proximal peritumoral region and diminished with increasing distance from tumor margins.ConclusionUsing FWE tractometry on a large clinical repository, we identified distinct pathology-specific patterns of white matter alteration. Glioblastoma showed extensive direct involvement and peritumoral microstructural changes, while oligodendroglioma demonstrated relatively preserved white matter architecture near tumor margins. These patterns reflect expected biological differences and provide a reproducible framework for characterizing extent of white matter involvement, with potential applications in presurgical planning and understanding recurrence patterns.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11060-025-05370-w.

Abstract The long-term occurrence of Mesospheric Inversion Layers (MILs) was analyzed using 22 years (2002–2023) of SABER temperature data. The two types of MILs considered are those caused by dissipating waves and those caused by non-dissipating waves. We examined MIL occurrence near-globally, monthly, and latitudinally, applying multi-linear regression (MLR) to assess trends and responses to El Niño Southern Oscillation (ENSO), quasi-biennial oscillation (QBO), and solar flux ( F 10.7cm ). MIL parameters (top/base heights and temperatures, height/temperature variations) exhibit clear hemispherical asymmetry. In general, MIL occurrences peak during equinoxes and decline during solstices. Latitudinally, tropical regions (30°N–30°S) show the highest MIL occurrences during equinoxes and the lowest during solstices. In mid-latitudes and polar regions (30°–83°N/S), MILs peak in autumn and winter, with a minimum in spring and summer. Periodicities in MIL occurrences vary near-globally and by latitude. The tropics feature the smallest mean thickness variation (~ 0.61km) but the largest mean temperature amplitude variation (~23.72K). The latitudinal patterns may reflect seasonal variations in dynamics that have a stronger influence on temperature inversions than on the vertical distributions in the mesosphere. Over 22 years, analysis revealed a near-global MIL occurrence ratio increase of approximately 0.055±0.016% per year, with the 11-year solar cycle exerting significant control. The observed negative correlation with ENSO and positive correlation with QBO likely reflect their influence on atmospheric wave propagation and circulation, which indirectly modulates MIL formation.

The relation between neuroinflammation, amyloid-β load, grey matter loss and brain activity in visual object recognition regions in Alzheimer's Disease

Abstract The occurrence time of the equatorial ionization anomaly (EIA) crest, denoted as T EIA , is a sensitive indicator of low‐latitude ionosphere–thermosphere coupling. However, its systematic modulation over multiple solar cycles has remained unclear. Using Global Ionospheric Maps (GIM, 2003–2022), ICON/MIGHTI neutral winds (2019–2022), the HWM‐93 model, and Equatorial Electrojet (EEJ) data and models, we quantify the solar‐cycle modulation of T EIA and elucidate the governing physical mechanisms. Our 20‐year analysis reveals that T EIA advances (delays) on average by ∼0.2 hr during solar minimum (maximum), potentially following the interannual variation of solar activity. This modulation is possibly driven by dual‐driver mechanisms: (a) Enhanced equatorial electric fields (EEF, proxied by EEJ) during solar maximum strengthen the equatorial plasma fountain, extending the crests' position and prolonging their development; and (b) the amplitude of the meridional wind at ∼300 km anti‐correlates with solar activity, with weakened wind during solar maximum slowing poleward diffusion. This work elucidates the physical mechanisms of T EIA variability, offering new insights into low‐latitude ionospheric dynamics and practical implications for space‐weather prediction.

BackgroundTau pathology distribution in Alzheimer's disease (AD) shows individual spatial heterogeneity, including hemispheric asymmetry. The mechanisms underlying this asymmetry remain unclear. This study explored whether tau asymmetry is linked to reduced inter‐hemispheric connectivity, potentially restricting tau spread, or reflects asymmetry in amyloid‐beta (Aβ) distribution, indicating hemisphere‐specific vulnerability to early Aβ pathology.MethodThe study included 837 Aβ‐positive (CSF Aβ42/40<0.08 or cortical Aβ‐PET>1.033) participants from the Swedish BioFINDER‐2 cohort with available tau‐PET scan(s). A cross‐sectional subsample of 452 subjects with evidence of tau pathology based on temporal meta‐ROI (Braak I‐IV; SUVR>1.362) was selected and categorised as left asymmetric (n = 102), symmetric (n = 306), or right asymmetric (n = 44) using a laterality index (LI; see Figure 1). First, edge‐wise inter‐hemispheric structural (diffusion‐MRI, n = 352) and functional (rs‐fMRI, n = 318) connectivity were compared between the tau asymmetry groups using the Desikan‐Killiany parcellation. Only the top 10% inter‐hemispheric connections identified in a separate control sample were analysed. Second, the association between Aβ and tau laterality patterns was investigated using linear regression on LI values and validated in three independent cohorts (OASIS‐3, A4, ADNI). Finally, in a longitudinal subsample (n = 289; average follow‐up = 2.9 years) of Aβ‐positive participants with multiple tau‐PET scans, stratified into A+T‐ (n = 180) and A+T+ (n = 109) groups based on pathology at baseline, linear mixed effect models were used to assess the association between baseline Aβ laterality and tau laterality change over time.ResultCross‐sectionally, no differences in average edge‐wise inter‐hemispheric functional or structural connectivity were found between tau asymmetric and symmetric groups (Figure 2a). In contrast, a strong association was observed between tau and Aβ laterality patterns (Figure 2b; β=0.632, p <0.001), which was replicated in three independent cohorts (Figure 2c; all p <0.005). In the longitudinal A+ sample, the degree of Aβ asymmetry at baseline predicted progression of tau laterality over time (Figure 3a; β=0.025, p = 0.028), with the strongest interaction effect in the Braak III‐IV meta‐ROI in A+T‐ individuals (Figure 3b; β=0.080, p <0.001) but not in A+T+ (Figure 3c).ConclusionThese findings suggest that tau asymmetry is not associated with differences in macro‐scale inter‐hemispheric individual connectivity but reflects hemispheric differences in vulnerability to Aβ pathology.

BackgroundCerebrovascular disease (CVD) is a leading cause of mortality with a strong link to cognitive impairment and dementia. White matter lesions (WML) are prevalent in CVD and are early markers of vascular compromise, particularly in relation to intraplaque hemorrhage (IPH), an indicator of carotid artery plaque instability. As vascular disease represents a possible treatment window for dementia subjects, this study explores the relationship between hemispheric WML asymmetry and IPH utilizing a large multicenter cohort to find novel biomarkers of disease.MethodFLAIR MRI scans of 264 subjects from the Canadian Atherosclerosis Imaging Network were categorized as IPH positive (IPH+) or IPH negative (IPH‐) and WML biomarkers were automatically computed (Figure 1). Biomarkers related to WML prevalence (volume) and WML ischemia and progression (intensity) were extracted: ICV‐normalized WML volume (WML‐ICV), WML mean intensity (WML‐Intensity), and WML intensity ratio (WML‐IR). WML asymmetry was assessed via an asymmetry index measure (AIM). Linear mixed models and regression analyses were conducted, with adjustments for age, sex, scanner manufacturer, and stenosis, to evaluate associations between WML biomarkers and IPH status.ResultIPH+ patients exhibited significant rightward asymmetry in WML‐ICV (0.0032 ± 0.002, p < 0.05), WML‐Intensity (7.26 ± 5.41, p < 0.05), and WML‐IR (0.0271 ± 0.0204, p < 0.05); Table 1. IPH+ subjects (left, right or bilateral) had more lesions that were brighter in the right hemisphere. This trend was most pronounced in younger male patients (<65 years), suggesting a high‐risk demographic. Regression analysis revealed IPH as a significant predictor of WML asymmetry, with stronger effects observed in subjects with IPH in the right carotid artery.ConclusionPrevious studies suggest more injury in the right hemisphere for subjects with small vessel disease, and this work supports this finding. With rightward WML asymmetry being strongly associated with IPH, this could be reflecting a surrogate marker for overall vascular disease and its contribution to brain health and dementia. Automated WML biomarkers can be used to identify these high‐risk patients and guide early interventions for subjects with vascular disease and dementia. Future work should validate these findings in larger, longitudinal datasets to enhance clinical applications.

The origin of small deviations from statistical isotropy in the Cosmic Microwave Background (CMB) — the so-called CMB anomalies — remains an open question in modern cosmology. In this work, we test statistical isotropy in Planck Data Release 4 (PR4) by estimating the temperature and E-mode power spectra across independent sky regions. We find that the directions with higher local bandpower amplitudes in intensity are clustered for multipoles between 200 and 2000 with clustering probabilities consistently below 1% for all these scales when compared to end-to-end (E2E) Planck simulations; notably, this range extends beyond that reported in Planck Data Release 3 (PR3). On the other hand, no significant clustering is observed in the polarisation E-modes. In a complementary analysis, we search for dipolar variations in cosmological parameters fitted using the previously computed power spectra. When combining temperature and polarisation power spectra, we identify a potential anomaly in the amplitude of the primordial power spectrum, As , with only 5 out of 600 simulations exhibiting a dipole amplitude as large as that observed in the data. Interestingly, the dipole direction aligns closely with the known hemispherical power asymmetry, suggesting a potential link between these anomalies. All other cosmological parameters remain consistent with ΛCDM expectations. Our findings highlight the need to further investigate these anomalies and understand their nature and potential implications for better understanding of the early Universe.

Repetitive exposure to prismatic adaptation in post-stroke optic ataxia: a single case study exploring behavioural changes and brain functional reorganization.