Arrow Research search

Author name cluster

Jörg B. Schulz

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

10 papers
1 author row

Possible papers

10

YNIMG Journal 2026 Journal Article

Fronto-cerebellar connectivity disruptions and functional reorganization in Friedreich’s Ataxia: A structural and resting-state fMRI study

  • Ravi Dadsena
  • Sandro Romanzetti
  • Stella Andrea Lischewski
  • Yinghua Jing
  • Dagmar Timmann
  • Jennifer Faber
  • Jörg B. Schulz
  • Kathrin Reetz

Friedreich's ataxia (FRDA) is an inherited neurodegenerative disorder characterized by progressive ataxia and multisystem manifestations resulting from involvement of the peripheral and central nervous systems. While regional atrophy is known to be associated with symptoms, functional network alterations may represent a critical pathological mechanism; however, their specific contribution to motor and cognitive impairment remains unclear. We combined T1-weighted anatomical MRI and resting-state functional MRI (rs-fMRI) in 37 individuals with FRDA and 41 age- and sex-matched healthy controls and explored how functional connectivity differences are related to atrophy, clinical severity and cognitive performance. Regional volumes were quantified using morphometry analyses, spontaneous rs-fMRI activity was assessed via amplitudes of low-frequency fluctuations, and functional co-activation was evaluated among regions showing structural and neuronal activity alterations. Volume reductions were most pronounced in the brainstem, cerebellar white matter, hemisphere of lobules VI, X, and thalamus. Functionally, individuals with FRDA showed decreased fronto-cerebellar connectivity alongside increased intracerebellar, thalamo-striatal, and hippocampal-cerebellar coupling. Infratentorial and thalamic volume loss correlated strongly with clinical disease severity, whereas reduced frontal co-activation with cerebellar lobules VI, Crus I and II was moderately associated with poorer motor and cognitive performance. In contrast, increased intracerebellar and hippocampal-cerebellar coupling was observed particularly in individuals with more advanced disease and was partly associated with better cognitive outcomes. These findings indicate widespread disruptions of long-range cerebro-cerebellar connectivity together with increased intraregional coupling and potential network reorganization, underscoring the importance of network-level mechanisms for understanding clinical heterogeneity in FRDA and guiding future prognostic and therapeutic studies.

Details DOI

YNICL Journal 2022 Journal Article

3T sodium MR imaging in Alzheimer’s disease shows stage-dependent sodium increase influenced by age and local brain volume

  • Alexa Haeger
  • Fawzi Boumezbeur
  • Michel Bottlaender
  • Cécile Rabrait-Lerman
  • Julien Lagarde
  • Shahram Mirzazade
  • Janna Krahe
  • Christian Hohenfeld

INTRODUCTION: Na-MRI in a larger cohort and on a clinical 3T MR scanner. METHODS: We used a multimodal MRI protocol on 52 prodromal to mild AD patients and 34 cognitively healthy control subjects on a clinical 3T MR scanner. We examined the TSC, brain volume, and cortical thickness in association with clinical parameters. We further compared TSC with intra-individual normalized TSC for the reduction of inter-individual TSC variability resulting from physiological as well as experimental conditions. Normalized TSC maps were created by normalizing each voxel to the mean TSC inside the brain stem. RESULTS: We found increased normalized TSC in the AD cohort compared to elderly control subjects both on global as well as on a region-of-interest-based level. We further confirmed a significant association of local brain volume as well as age with TSC. TSC increase in the left temporal lobe was further associated with the cognitive state, evaluated via the Montreal cognitive assessment (MoCA) screening test. An increase of normalized TSC depending on disease stage reflected by the Clinical Dementia Rating (CDR) was found in our AD patients in temporal lobe regions. In comparison to classical brain volume and cortical thickness assessments, normalized TSC had a higher discriminative power between controls and prodromal AD patients in several regions of the temporal lobe. DISCUSSION: Na-MRI in association with other metabolic imaging marker needs to be further elucidated.

Details DOI

YNICL Journal 2022 Journal Article

Increased brain tissue sodium concentration in Friedreich ataxia: A multimodal MR imaging study

  • Janna Krahe
  • Imis Dogan
  • Claire Didszun
  • Shahram Mirzazade
  • Alexa Haeger
  • Nadim Joni Shah
  • Ilaria A. Giordano
  • Thomas Klockgether

In patients with Friedreich ataxia, structural MRI is typically used to detect abnormalities primarily in the brainstem, cerebellum, and spinal cord. The aim of the present study was to additionally investigate possible metabolic changes in Friedreich ataxia using in vivo sodium MRI that may precede macroanatomical alterations, and to explore potential associations with clinical parameters of disease progression. Tissue sodium concentration across the whole brain was estimated from sodium MRI maps acquired at 3 T and compared between 24 patients with Friedreich ataxia (21-57 years old, 13 females) and 23 controls (21-60 years old, 12 females). Tensor-based morphometry was used to assess volumetric changes. Total sodium concentrations and volumetric data in brainstem and cerebellum were correlated with clinical parameters, such as severity of ataxia, activity of daily living and disability stage, age, age at onset, and disease duration. Compared to controls, patients showed reduced brain volume in the right cerebellar lobules I-V (difference in means: -0.039% of total intracranial volume [TICV]; Cohen's d = 0.83), cerebellar white matter (WM) (-0.105%TICV; d = 1.16), and brainstem (-0.167%TICV; d = 1.22), including pons (-0.102%TICV; d = 1.00), medulla (-0.036%TICV; d = 1.72), and midbrain (-0.028%TICV; d = 1.05). Increased sodium concentration was additionally detected in the total cerebellum (difference in means: 2.865 mmol; d = 0.68), and in several subregions with highest effect sizes in left (5.284 mmol; d = 1.01) and right cerebellar lobules I-V (5.456 mmol; d = 1.00), followed by increases in the vermis (4.261 mmol; d = 0.72), and in left (2.988 mmol; d = 0.67) and right lobules VI-VII (2.816 mmol; d = 0.68). In addition, sodium increases were also detected in all brainstem areas (3.807 mmol; d = 0.71 to 5.42 mmol; d = 1.19). After controlling for age, elevated total sodium concentrations in right cerebellar lobules IV were associated with younger age at onset (r = -0.43) and accordingly with longer disease duration in patients (r = 0.43). Our findings support the potential of in vivo sodium MRI to detect metabolic changes of increased total sodium concentration in the cerebellum and brainstem, the key regions in Friedreich ataxia. In addition to structural changes, sodium changes were present in cerebellar hemispheres and vermis without concomitant significant atrophy. Given the association with age at disease onset or disease duration, metabolic changes should be further investigated longitudinally and in larger cohorts of early disease stages to determine the usefulness of sodium MRI as a biomarker for early neuropathological changes in Friedreich ataxia and efficacy measure for future clinical trials.

Details DOI

YNICL Journal 2019 Journal Article

Cerebral changes improved by physical activity during cognitive decline: A systematic review on MRI studies

  • Alexa Haeger
  • Ana S. Costa
  • Jörg B. Schulz
  • Kathrin Reetz

Current treatment in late-life cognitive impairment and dementia is still limited, and there is no cure for brain tissue degeneration or reversal of cognitive decline. Physical activity represents a promising non-pharmacological interventional approach in many diseases causing cognitive impairment, but its effect on brain integrity is still largely unknown. Especially research of cerebral alterations in disease state that goes beyond observations of clinical improvement is crucial to understand disease processes and possible effective treatments. In this systematic review, we address the question how physical activity and fitness in mild cognitive impairment (MCI) and Alzheimer's disease (AD) influences brain architecture compared to cognitively healthy elderly. We review both interventional studies comprising aerobic, coordinative and resistance exercises and observational studies on fitness and physical activity combined with Magnetic Resonance imaging (MRI). Different MRI approaches were included such as volumetric and structural analyses, Diffusion Tensor Imaging (DTI), functional MRI and Cerebral Blood Flow (CBF). We evaluate MRI results for different exercise modalities and performed a methodological evaluation of interventional studies in cognitive decline compared to normal aging. According to our results, among 12 interventions in AD/MCI, aerobic exercise is most frequently applied (9 studies). Interventions in AD/MCI altogether reveal a higher methodological quality compared to interventions in healthy elderly (8.33 ± 2.19 vs. 6.25 ± 2.36 out of 13 points), with most frequent missing aspects related to descriptions of complications, lack of intention-to-treat and statistical power analyses. Effects of aerobic exercise and fitness seem to mainly impact brain structures sensitive to neurodegeneration, which especially comprise frontal, temporal and parietal regions, such as the hippocampal/parahippocampal region, precuneus, anterior cingulate and prefrontal cortex, which are reported by several studies. General fitness measured via an objective fitness assessment and questionnaires seems to have a more global cerebral effect, probably due to its long-term application, whereas distinct intervention effects of durations between 3 and 6 months seem to concentrate on more local brain regions as the hippocampus, which can also be influenced by region of interest analyses. There is still a lack of evidence on other or combined types of intervention modalities, such as resistance, coordinative as well as multicomponent exercise during cognitive decline, and complex interventions as dancing. Future research should examine their beneficial effect on brain integrity, since several non-MRI studies already point to their advantageous impact. As a further future prospect, combination and application of newly developed imaging methods such as metabolic imaging should be envisaged to understand physical activity and its cerebral influence under its many-sided facets.

Details DOI

YNICL Journal 2015 Journal Article

Functional connectivity modeling of consistent cortico-striatal degeneration in Huntington's disease

  • Imis Dogan
  • Claudia R. Eickhoff
  • Peter T. Fox
  • Angela R. Laird
  • Jörg B. Schulz
  • Simon B. Eickhoff
  • Kathrin Reetz

Huntington's disease (HD) is a progressive neurodegenerative disorder characterized by a complex neuropsychiatric phenotype. In a recent meta-analysis we identified core regions of consistent neurodegeneration in premanifest HD in the striatum and middle occipital gyrus (MOG). For early manifest HD convergent evidence of atrophy was most prominent in the striatum, motor cortex (M1) and inferior frontal junction (IFJ). The aim of the present study was to functionally characterize this topography of brain atrophy and to investigate differential connectivity patterns formed by consistent cortico-striatal atrophy regions in HD. Using areas of striatal and cortical atrophy at different disease stages as seeds, we performed task-free resting-state and task-based meta-analytic connectivity modeling (MACM). MACM utilizes the large data source of the BrainMap database and identifies significant areas of above-chance co-activation with the seed-region via the activation-likelihood-estimation approach. In order to delineate functional networks formed by cortical as well as striatal atrophy regions we computed the conjunction between the co-activation profiles of striatal and cortical seeds in the premanifest and manifest stages of HD, respectively. Functional characterization of the seeds was obtained using the behavioral meta-data of BrainMap. Cortico-striatal atrophy seeds of the premanifest stage of HD showed common co-activation with a rather cognitive network including the striatum, anterior insula, lateral prefrontal, premotor, supplementary motor and parietal regions. A similar but more pronounced co-activation pattern, additionally including the medial prefrontal cortex and thalamic nuclei was found with striatal and IFJ seeds at the manifest HD stage. The striatum and M1 were functionally connected mainly to premotor and sensorimotor areas, posterior insula, putamen and thalamus. Behavioral characterization of the seeds confirmed that experiments activating the MOG or IFJ in conjunction with the striatum were associated with cognitive functions, while the network formed by M1 and the striatum was driven by motor-related tasks. Thus, based on morphological changes in HD, we identified functionally distinct cortico-striatal networks resembling a cognitive and motor loop, which may be prone to early disruptions in different stages of the disease and underlie HD-related cognitive and motor symptom profiles. Our findings provide an important link between morphometrically defined seed-regions and corresponding functional circuits highlighting the functional and ensuing clinical relevance of structural damage in HD.

Details DOI