Brain communications最新文献

{"title":"Exploratory analysis of biological age measures in a remyelination clinical trial.","authors":"Christopher E McMurran, Ermelinda de Meo, Nick G Cunniffe, J William L Brown, Ferran Prados, Baris Kanber, James H Cole, Alasdair J Coles, Sara Hägg, Declan T Chard","doi":"10.1093/braincomms/fcaf032","DOIUrl":"10.1093/braincomms/fcaf032","url":null,"abstract":"<p><p>Enhancing CNS myelin repair (remyelination) is a promising strategy to prevent neurodegeneration and associated progressive disability in multiple sclerosis. Remyelination becomes inefficient with older chronological age, but the relationship between measures of biological age and remyelination has not been previously described in a clinical cohort. Here, we investigated two measures of biological age amongst participants of the Cambridge Centre for Myelin Repair One trial of bexarotene: MRI brain age (BA_MRI) and a blood-based biological age (BA_Blood). In people with radiologically stable multiple sclerosis (<i>n</i> = 44 of 49 total participants), we found that treatment with bexarotene, along with promoting remyelination, was associated with significant decrease in MRI brain age [-1.98 years, 95% confidence interval (CI) [-3.75, -0.21 years] versus placebo over 6 months, <i>P</i> = 0.034]. Whilst BA_MRI increased as expected during the trial in the placebo group (+0.92 years, CI [-0.41, 2.26]), the brain MRIs of participants treated with bexarotene appeared on average 11 months younger at the end compared to the start of the trial (-0.93 years, CI [-2.02, 0.17]). The effect of bexarotene on BA_MRI was associated with its remyelinating activity in cortical grey matter lesions (<i>β</i> = 0.25% units (pu)/year, CI [0.03, 0.46], <i>P</i> = 0.023) and brainstem lesions (<i>β</i> = 0.24 pu/year, CI [0.09, 0.39], <i>P</i> = 0.003). We also observed some regional trends that the remyelinating response to bexarotene was linked with measures of biological age at baseline. For example, after adjustment for chronological age, remyelination of brainstem lesions assessed by magnetization transfer ratio was reduced by 0.06 pu for each year increase in BA_MRI (CI [0.00, 0.13], <i>P</i> = 0.058) and 0.02 pu for each year increase in BA_Blood (CI [-0.01, 0.05], <i>P</i> = 0.17). This is, to the best of our knowledge, the first demonstration that MRI brain age can be therapeutically modulated by a drug in people with a neurological disorder. Overall, these findings highlight that beyond chronological age, biological age may also influence the potential for repair and should be considered when developing treatments for multiple sclerosis.</p>","PeriodicalId":93915,"journal":{"name":"Brain communications","volume":"7 1","pages":"fcaf032"},"PeriodicalIF":4.1,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11852336/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143506012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unmasking paramagnetic rim multiple sclerosis lesions: the advantages of quantitative susceptibility mapping over phase imaging.","authors":"Àlex Rovira, Deborah Pareto","doi":"10.1093/braincomms/fcaf037","DOIUrl":"10.1093/braincomms/fcaf037","url":null,"abstract":"<p><p>This scientific commentary refers to 'Quantitative susceptibility mapping is more sensitive and specific than phase imaging in detecting chronic active multiple sclerosis lesion rims: pathological validation', by Gillen <i>et al</i>. (https://doi.org/10.1093/braincomms/fcaf011).</p>","PeriodicalId":93915,"journal":{"name":"Brain communications","volume":"7 1","pages":"fcaf037"},"PeriodicalIF":4.1,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11800473/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143367146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cortical involvement of lateral trunk flexion and verticality misperception in Parkinson's disease.","authors":"Masayuki Kohsaka, Tomoko Oeda, Shigetoshi Takaya, Satoshi Tomita, Kwiyoung Park, Kenji Yamamoto, Hidenao Fukuyama, Hideyuki Sawada","doi":"10.1093/braincomms/fcaf040","DOIUrl":"10.1093/braincomms/fcaf040","url":null,"abstract":"<p><p>Lateral trunk flexion is a common form of postural abnormality in Parkinson's disease and could be associated with verticality misperception. However, the mechanisms underlying lateral trunk flexion and verticality misperception in Parkinson's disease remain unclear. In the current study, we examined whether lateral trunk flexion is associated with verticality misperception in patients with Parkinson's disease. We also identified the brain regions involved in lateral trunk flexion and altered verticality perception. In this cross-sectional study, we evaluated the verticality perception using the subjective visual vertical test in 81 patients with Parkinson's disease and 14 age-matched healthy controls. According to the 97.5th percentile upper reference limit of the body tilt angle in the healthy controls, patients with Parkinson's disease were grouped into 37 patients with lateral trunk flexion and 44 patients without lateral trunk flexion. The mean of absolute subjective visual vertical angles was compared between patients with Parkinson's disease with lateral trunk flexion, those without lateral trunk flexion, and the healthy controls, and the impact of verticality misperception on lateral trunk flexion was evaluated using multivariate logistic regression models. We further performed a voxel-wise comparison of regional cerebral blood flow using N-isopropyl-p-[¹²³I] iodoamphetamine single-photon emission computed tomography (height threshold of <i>P</i> < 0.001, uncorrected for multiple comparisons, extent threshold of 100 voxels) to identify the brain regions associated with lateral trunk flexion, and to investigate the relationship between verticality misperception and regional hypoperfusion. The mean of absolute subjective visual vertical angles was larger in patients with Parkinson's disease with and without lateral trunk flexion than in healthy controls (<i>P</i> < 0.001 and <i>P</i> < 0.001). Additionally, the subjective visual vertical angle was associated with the presence of lateral trunk flexion (odds ratio 2.25, 95% confidence interval 1.51-3.36, <i>P</i> < 0.001). The regional cerebral blood flow in patients with Parkinson's disease with lateral trunk flexion was decreased in the right inferior parietal lobule, right superior parietal lobule, right superior temporal gyrus, and right dorsal posterior cingulate cortex compared with those without lateral trunk flexion. The subjective visual vertical angle was inversely correlated with regional cerebral blood flow in these regions, except for the dorsal posterior cingulate cortex. Our study reveals that hypofunction in the right temporoparietal association cortices is involved in verticality misperception and the development of lateral trunk flexion in patients with Parkinson's disease. These results provide insights into potential therapeutic targets for addressing lateral trunk flexion.</p>","PeriodicalId":93915,"journal":{"name":"Brain communications","volume":"7 1","pages":"fcaf040"},"PeriodicalIF":4.1,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11806416/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143384490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Myths and facts about alcohol use disorder: a Delphi consensus study.","authors":"Sophie Hytner, Daphne Josselin, David Belin, Owen Bowden Jones","doi":"10.1093/braincomms/fcaf035","DOIUrl":"10.1093/braincomms/fcaf035","url":null,"abstract":"<p><p>Educational interventions that counter myths about alcohol use disorder with facts have the potential to reduce public stigma. Few such interventions have hitherto been rigorously developed. Using a Delphi expert consensus method, this study identified myths and facts to include in an intervention targeting the public stigma of alcohol use disorder. Sixteen UK-based experts (four academics, five clinicians and seven experts-by-experience) completed three sequential online survey rounds. The first round was used alongside a systematic review of the literature on public alcohol use disorder stereotypes to develop 13 myth-fact pairs, which participants quantitively scored in subsequent rounds to determine their importance for inclusion. Pairs reaching consensus (>70% agreement) on high importance (mean score, 7-9) challenged beliefs that alcohol use disorder '<i>only affects certain groups'</i>, and that people with alcohol use disorder '<i>cannot recover'</i>, are '<i>to blame'</i> for, and '<i>able to control'</i>, their drinking. The myth-fact pairs scored as most important relate to responsibility- and recovery-based themes and provide a basis for future educational interventions for public alcohol use disorder stigma.</p>","PeriodicalId":93915,"journal":{"name":"Brain communications","volume":"7 1","pages":"fcaf035"},"PeriodicalIF":4.1,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11806414/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143384508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The genetic landscape and classification of infantile epileptic spasms syndrome requiring surgery due to suspected focal brain malformations.","authors":"Matthew Coleman, Min Wang, Penny Snell, Wei Shern Lee, Colleen D'Arcy, Cristina Mignone, Kate Pope, Greta Gillies, Wirginia Maixner, Alison Wray, A Simon Harvey, Cas Simons, Richard J Leventer, Sarah E M Stephenson, Paul J Lockhart, Katherine B Howell","doi":"10.1093/braincomms/fcaf034","DOIUrl":"10.1093/braincomms/fcaf034","url":null,"abstract":"<p><p>Infantile epileptic spasms syndrome is a severe epilepsy of infancy that is often associated with focal malformations of cortical development. This study aimed to elucidate the genetic landscape and histopathologic aetiologies of infantile epileptic spasms syndrome due to focal malformations of cortical development requiring surgery. Fifty-nine children with a history of infantile epileptic spasms syndrome and focal malformations of cortical development on MRI were studied. Genetic testing of resected brain tissue was performed by high-coverage targeted panel sequencing or exome sequencing. Histopathology and MRI were reviewed, and integrated clinico-pathological diagnoses were established. A genetic diagnosis was achieved in 47 children (80% of cohort). Germline pathogenic variants were identified in 27/59 (46%) children, in <i>TSC2</i> (x19), <i>DEPDC5</i> (x2), <i>CDKL5</i> (x2), <i>NPRL3</i> (x1), <i>FGFR1</i> (x1), <i>TSC1</i> (x1), and one child with both a <i>TUBB2A</i>/<i>TUBB2B</i> deletion and a pathogenic variant in <i>COL4A1</i> (x1). Pathogenic brain somatic variants were identified in 21/59 (36%) children, in <i>SLC35A2</i> (x9), <i>PIK3CA</i> (x3), <i>AKT3</i> (x2), <i>TSC2</i> (x2), <i>MTOR</i> (x2), <i>OFD1</i> (x1), <i>TSC1</i> (x1) and <i>DEPDC5</i> (x1). One child had 'two-hit' diagnosis, with both germline and somatic pathogenic <i>DEPDC5</i> variants in trans. Multimodal data integration resulted in clinical diagnostic reclassifications in 24% of children, emphasizing the importance of combining genetic, histopathologic and imaging findings. Mammalian target of rapamycin pathway variants were identified in most children with tuberous sclerosis or focal cortical dysplasia type II. All nine children with somatic <i>SLC35A2</i> variants in brain were reclassified to mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy. Somatic mosaicism was a major cause of focal cortical dysplasia type II/hemimegalencephaly (81%) and mild malformation of cortical development with oligodendroglial hyperplasia (100%). The genetic landscape of infantile epileptic spasms syndrome due to focal malformations comprises germline and somatic variants in a range of genes, with mTORopathies and <i>SLC35A2</i>-related mild malformation of cortical development with oligodendroglial hyperplasia being the major causes. Multimodal data integration incorporating genetic data aids in optimizing diagnostic pathways and can guide surgical decision-making and inform future research and therapeutic interventions.</p>","PeriodicalId":93915,"journal":{"name":"Brain communications","volume":"7 1","pages":"fcaf034"},"PeriodicalIF":4.1,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11806418/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143383700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CSF biomarkers are differentially linked to brain areas high and low in noradrenaline, dopamine and serotonin across the Alzheimer's disease spectrum.","authors":"Lena Haag, Elisa Lancini, Renat Yakupov, Gabriel Ziegler, Yeo-Jin Yi, Falk Lüsebrink, Wenzel Glanz, Oliver Peters, Eike Jakob Spruth, Slawek Altenstein, Josef Priller, Luisa Sophie Schneider, Xiao Wang, Lukas Preis, Frederic Brosseron, Nina Roy-Kluth, Klaus Fliessbach, Michael Wagner, Steffen Wolfsgruber, Luca Kleineidam, Alfredo Ramirez, Annika Spottke, Frank Jessen, Jens Wiltfang, Anja Schneider, Niels Hansen, Ayda Rostamzadeh, Katharina Buerger, Michael Ewers, Robert Perneczky, Daniel Janowitz, Boris-Stephan Rauchmann, Stefan Teipel, Ingo Kilimann, Doreen Goerss, Christoph Laske, Matthias H Munk, Michael Heneka, Peter Dechent, Stefan Hetzer, Klaus Scheffler, Emrah Düzel, Matthew J Betts, Dorothea Hämmerer","doi":"10.1093/braincomms/fcaf031","DOIUrl":"10.1093/braincomms/fcaf031","url":null,"abstract":"<p><p>Neurotransmitter systems of noradrenaline, dopamine, serotonin and acetylcholine are implicated in cognitive functions such as memory, learning and attention and are known to be altered in neurodegenerative diseases like Alzheimer's disease. Specific brain structures involved in these systems, e.g. the locus coeruleus, the main source of noradrenaline in the cortex, are in fact affected earliest by Alzheimer's disease tau pathology. Preserved volumetric neurotransmitter specific brain areas could therefore be an important neural resource for cognitive reserve in aging. The aim of this study was to determine whether volumes of brain areas known to be high in neurotransmitter receptors are relatively preserved in individuals with lower levels of Alzheimer's disease pathology. Based on the Human Protein Atlas for neurotransmitter receptor distribution, we distinguished between 'areas high and low' in noradrenaline, dopamine, serotonin and acetylcholine and assessed associations of atrophy in those areas with CSF amyloid-ß 42/40, CSF phosphorylated tau protein and cognitive function across healthy controls (<i>n</i> = 122), individuals with subjective cognitive decline (<i>n</i> = 156), mild cognitive impairment or mild Alzheimer's disease dementia (<i>n</i> = 126) using structural equation modelling. CSF pathology markers were inversely correlated and showed a stronger association with disease severity, suggesting distinguishable interrelatedness of these biomarkers depending on the stage of Alzheimer's disease dementia. Across groups, amyloid pathology was linked to atrophy in areas high as well as low in neurotransmitter receptor densities, while tau pathology did not show any significant link to brain area volumes for any of the neurotransmitters. Within disease severity groups, individuals with more amyloid pathology showed more atrophy only in 'areas high in noradrenaline', whereas for dopamine tau pathology was linked to higher volumes in areas low in receptor density possibly indicating compensatory mechanisms. Furthermore, individuals with more tau pathology showed a selective decrease in memory function while amyloid pathology was related to a decline in executive function and language capacity as well as memory function. In summary, our analyses highlight the benefits of investigating disease-relevant factors in Alzheimer's disease using a multivariate multigroup approach. Assessing multivariate dependencies in different disease stages and across individuals revealed selective links of pathologies, cognitive decline and atrophy in particular for areas modulated by noradrenaline, dopamine and serotonin.</p>","PeriodicalId":93915,"journal":{"name":"Brain communications","volume":"7 1","pages":"fcaf031"},"PeriodicalIF":4.1,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11806415/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143384523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The challenge of long-term stroke outcome prediction and how statistical correlates do not imply predictive value.","authors":"Christoph Sperber, Laura Gallucci, Marcel Arnold, Roza M Umarova","doi":"10.1093/braincomms/fcaf003","DOIUrl":"10.1093/braincomms/fcaf003","url":null,"abstract":"<p><p>Personalized prediction of stroke outcome using lesion imaging markers is still too imprecise to make a breakthrough in clinical practice. We performed a combined prediction and brain mapping study on topographic and connectomic lesion imaging data to evaluate (i) the relationship between lesion-deficit associations and their predictive value and (ii) the influence of time since stroke. In patients with first-ever ischaemic stroke, we first applied high-dimensional machine learning models on lesion topographies or structural disconnection data to model stroke severity (National Institutes of Health Stroke Scale 24 h/3 months) and functional outcome (modified Rankin Scale 3 months) in cross-validation. Second, we mapped the topographic and connectomic lesion impact on both clinical measures. We retrospectively included 685 patients [age 67.4 ± 15.1, National Institutes of Health Stroke Scale 24 h median(IQR) = 3(1; 6), modified Rankin Scale 3 months = 1(0; 2), National Institutes of Health Stroke Scale 3 months = 0(0; 2)]. <i>Predictions</i> for acute stroke severity (National Institutes of Health Stroke Scale 24 h) were better with topographic lesion imaging (<i>R</i>² = 0.41) than with disconnection data (<i>R</i>² = 0.29, <i>P</i> = 0.0015), whereas predictions at 3 months (National Institutes of Health Stroke Scale/modified Rankin Scale) were generally close to chance level. In the analysis of lesion-deficit <i>associations</i>, the correlates of more severe acute stroke (National Institutes of Health Stroke Scale 24 h > 4) and poor functional outcome (modified Rankin Scale 3 months ≥ 2) were left-lateralized. The lesion location impact of both variables corresponded in right-hemisphere stroke with peaks in primary motor regions, but it markedly differed in left-hemisphere stroke. Topographic and disconnection lesion features predict <i>acute</i> stroke severity better than the <i>3-months</i> outcome. This suggests a likely higher impact of lesion-independent factors in the longer term and highlights challenges in the prediction of global functional outcome. Prediction and brain mapping diverge, and the existence of statistically significant associations-as here for 3-months outcomes-does not imply predictive value. Routine neurological scores better capture left- than right-hemispheric lesions, further complicating the challenge of outcome prediction.</p>","PeriodicalId":93915,"journal":{"name":"Brain communications","volume":"7 1","pages":"fcaf003"},"PeriodicalIF":4.1,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11756379/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143030436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Causal relationships between hippocampal volumetric traits and the risk of Alzheimer's disease: a Mendelian randomization study.","authors":"Lining Guo, Yayuan Chen, Zuhao Sun, Jiaxuan Zhao, Jia Yao, Zhihui Zhang, Minghuan Lei, Ying Zhai, Jinglei Xu, Yurong Jiang, Ying Wang, Hui Xue, Mengge Liu, Feng Liu","doi":"10.1093/braincomms/fcaf030","DOIUrl":"10.1093/braincomms/fcaf030","url":null,"abstract":"<p><p>Alzheimer's disease, a common and progressive neurodegenerative disorder, is associated with alterations in hippocampal volume, as revealed by neuroimaging research. However, the causal links between the volumes of the hippocampus and its subfield structures with Alzheimer's disease remain unknown. A genetic correlation analysis using linkage disequilibrium score regression was conducted to identify hippocampal volumetric traits linked to Alzheimer's disease. Following this, to examine the causal links between Alzheimer's disease and hippocampal volumetric traits, we applied a two-sample Mendelian randomization approach, utilizing a bidirectional framework. Seven hippocampal volumetric traits were found as genetically correlated with Alzheimer's disease in the genetic correlation analysis and were then included in the Mendelian randomization analyses. Inverse variance weighted Mendelian randomization analyses revealed that increased volumes in the left whole hippocampus, left hippocampal body, right presubiculum head and right cornu ammonis 1 head were causally related to higher risks of Alzheimer's disease. Conversely, a higher risk of Alzheimer's disease was causally associated with decreased volumes of the left hippocampal body and left whole hippocampus. These results were validated through other Mendelian randomization approaches and sensitivity analysis. Our findings uncover bidirectional causal relationships between Alzheimer's disease and hippocampal volumetric traits, suggesting not only the potential significance of these traits in predicting Alzheimer's disease but also the reciprocal influence of Alzheimer's disease on hippocampal volumes.</p>","PeriodicalId":93915,"journal":{"name":"Brain communications","volume":"7 1","pages":"fcaf030"},"PeriodicalIF":4.1,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11783321/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143082576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Substantia nigra and locus coeruleus microstructural abnormalities in isolated rapid eye movement sleep behaviour disorder and Parkinson's disease.","authors":"Jacopo Pasquini, Michael J Firbank, Laura Best, Victoria Foster, Charlotte Stewart, Vincenzo Silani, Rory Durcan, Gemma Roberts, George Petrides, Roberto Ceravolo, David J Brooks, Kirstie N Anderson, Nicola Pavese","doi":"10.1093/braincomms/fcaf023","DOIUrl":"10.1093/braincomms/fcaf023","url":null,"abstract":"<p><p>Substantia nigra (SN) and locus coeruleus (LC) are two catecholaminergic, neuromelanin-rich nuclei that are affected in Parkinson's disease (PD) and may show neuroimaging abnormalities before the onset of motor manifestations. The simultaneous, multimodal investigation of their microstructural abnormalities may provide useful insights on the spatial diffusion and tissue characteristics of neurodegeneration, and this may in turn help develop markers for disease-modifying clinical trials. Therefore, through neuromelanin-sensitive and diffusion MRI, we aimed to investigate microstructural abnormalities in those nuclei in isolated REM sleep behaviour disorder (iRBD) and PD. Fourteen participants with polysomnography-confirmed iRBD, 18 with PD and 18 healthy controls were scanned with structural, neuromelanin-sensitive and neurite orientation dispersion and density imaging (NODDI) MRI. iRBD participants also underwent dopamine transporter imaging. SN neuromelanin and NODDI diffusion parameters and LC neuromelanin signals were extracted. Motor and global cognitive assessments were also collected. iRBD and PD participants showed significantly reduced neuromelanin contrast in the LC middle section compared with healthy controls. PD also showed significantly reduced caudal LC and posterior SN neuromelanin signal. No differences in SN NODDI parameters were detected between iRBD and healthy controls. Five iRBD participants showed reduced striatal dopamine transporter. In the combined disease groups (iRBD and PD), significant associations were shown between SN neuromelanin signal and neurite density index (<i>r</i> = -0.610, corr-<i>p</i> = 0.001) and between SN neurite density index and free water fraction (<i>r</i> = 0.417, corr-<i>p</i> = 0.042). In the same group, motor scores were negatively associated with nigral neuromelanin signal (<i>r</i> = -0.404, corr-<i>p</i> = 0.044) and free water fraction (<i>r</i> = 0.486, corr-<i>p</i> = 0.018). In conclusion, iRBD participants showed significant neuromelanin loss in the LC, with a minority showing initial nigrostriatal dopaminergic abnormalities. Across the entire iRBD-PD spectrum, the association between SN neuromelanin signal loss, diffusion parameters and motor scores has the potential to capture different yet related aspects of SN degeneration.</p>","PeriodicalId":93915,"journal":{"name":"Brain communications","volume":"7 1","pages":"fcaf023"},"PeriodicalIF":4.1,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11806417/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143383699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neural pathway activation in the subthalamic region depends on stimulation polarity.","authors":"Seyyed Bahram Borgheai, Enrico Opri, Faical Isbaine, Eric R Cole, Roohollah Jafari Deligani, Nealen G Laxpati, Benjamin B Risk, Jon T Willie, Robert E Gross, Nicholas AuYong, Cameron C McIntyre, Svjetlana Miocinovic","doi":"10.1093/braincomms/fcaf006","DOIUrl":"10.1093/braincomms/fcaf006","url":null,"abstract":"<p><p>Deep brain stimulation (DBS) is an effective treatment for Parkinson's disease; however, there is limited understanding of which subthalamic pathways are recruited in response to stimulation. Here, by focusing on the polarity of the stimulus waveform (cathodic versus anodic), our goal was to elucidate biophysical mechanisms that underlie electrical stimulation in the human brain. In clinical studies, cathodic stimulation more easily triggers behavioural responses, but anodic DBS broadens the therapeutic window. This suggests that neural pathways involved respond preferentially depending on stimulus polarity. To experimentally compare the activation of therapeutically relevant pathways during cathodic and anodic subthalamic nucleus (STN) DBS, pathway activation was quantified by measuring evoked potentials resulting from antidromic or orthodromic activation in 15 Parkinson's disease patients undergoing DBS implantation. Cortical evoked potentials (cEPs) were recorded using subdural electrocorticography, DBS local evoked potentials (DLEPs) were recorded from non-stimulating contacts, and electromyography activity was recorded from arm and face muscles. We measured (i) the amplitude of short-latency cEP, previously demonstrated to reflect activation of the cortico-STN hyperdirect pathway, (ii) DLEP amplitude thought to reflect activation of STN-globus pallidus (GP) pathway and (iii) amplitudes of very short-latency cEPs and motor evoked potentials for activation of corticospinal/bulbar tract (CSBT). We constructed recruitment and strength-duration curves for each EP/pathway to compare the excitability for different stimulation polarities. We compared experimental data with the most advanced DBS computational models. Our results provide experimental evidence that subcortical cathodic and anodic stimulation activate the same pathways in the STN region and that cathodic stimulation is in general more efficient. However, relative efficiency varies for different pathways so that anodic stimulation is the least efficient in activating CSBT, more efficient in activating the hyperdirect pathway and as efficient as cathodic in activating STN-GP pathway. Our experiments confirm biophysical model predictions regarding neural activations in the central nervous system and provide evidence that stimulus polarity has differential effects on passing axons, terminal synapses, and local neurons. Comparison of experimental results with clinical DBS studies provides further evidence that the hyperdirect pathway may be involved in the therapeutic mechanisms of DBS.</p>","PeriodicalId":93915,"journal":{"name":"Brain communications","volume":"7 1","pages":"fcaf006"},"PeriodicalIF":4.1,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11839843/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143470296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}