ORCID Profile
0000-0002-9503-2093
Current Organisation
National Neuroscience Institute
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Publisher: Springer Science and Business Media LLC
Date: 20-02-2019
DOI: 10.1038/S41598-018-37905-9
Abstract: The hippoc us is a key component of emotional and memory circuits and is broadly connected throughout the brain. We tracked the whole-brain connections of white matter fibres from the hippoc us using ultra-high angular resolution diffusion MRI in both a single 1150-direction dataset and a large normal cohort (n = 94 391-directions). Using a connectomic approach, we identified six dominant pathways in terms of strength, length and anatomy, and characterised them by their age and gender variation. The strongest in idual connection was to the ipsilateral thalamus. There was a strong age dependence of hippoc al connectivity to medial occipital regions. Overall, our results concur with preclinical and ex-vivo data, confirming that meaningful in vivo characterisation of hippoc al connections is possible in an in idual. Our findings extend the collective knowledge of hippoc al anatomy, highlighting the importance of the spinal-limbic pathway and the striking lack of hippoc al connectivity with motor and sensory cortices.
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.JOCN.2019.02.007
Abstract: Occipital bending (OB) describes asymmetry of the occipital lobes where one lobe wraps across the midline, and has been associated with the presence of mood disorders. We evaluated the relationship between OB and major depressive disorder (MDD) in a large population of subjects from the International Study to Predict Optimized Treatment in Depression. MDD patients (n = 231) and healthy controls (n = 68) underwent MRI and neuropsychiatric evaluation, including response or remission to antidepressant medication at baseline and at 8 weeks. Cortical thickness, ventricular volumes and regional grey matter volumes were measured. OB was visually assessed and OB angle measured using a semi-automated method. Correlations with MDD diagnosis, MRI measures and clinical features were tested. Results demonstrated a greater proportion of rightwards OB in MDD compared to control subjects (p = 0.02). There was no difference in the total prevalence of OB (combined left and rightward bending) between MDD and controls. MDD subjects with right OB had greater cortical thickness in three medial occipital regions (cuneus, lingual gyrus and calcarine sulcus) on the left. Lateral ventricular size was 20% lower bilaterally in right OB MDD subjects compared to non-OB MDD subjects. OB was not associated with severity (HDRS-17). Our data suggest the presence of a strong link between greater rightward occipital bending and MDD. Rightward-OB is associated with greater left medial occipital cortical thickness, and with reduced lateral ventricular size. The cause for greater rightward bending in MDD patients is unclear, however our data suggest a developmental aetiology.
Publisher: Elsevier BV
Date: 2020
Publisher: Elsevier BV
Date: 2019
Publisher: Mary Ann Liebert Inc
Date: 03-2020
Publisher: Radiological Society of North America (RSNA)
Date: 04-2015
Abstract: To identify statistical consensus between published studies for distribution and functional relevance of tract white matter (WM) degradation in multiple sclerosis (MS). By systematically searching online databases, tract-based spatial statistics studies were identified that compared fractional anisotropy (FA a marker for WM integrity) in MS patients to healthy control subjects, correlated FA in MS patients with physical disability, or correlated FA in MS patients with cognitive performance. Voxelwise meta-analysis was performed by using the Signed Differential Mapping method for each comparison. Moderating effects of mean age, mean physical disability score, imager magnet strength, lesion load, and number of diffusion directions were assessed by means of meta-regression. Meta-analysis was performed on data from 495 patients and 253 control subjects across 12 studies. MS diagnosis was significantly associated with widespread lower tract FA (nine studies largest cluster, 4379 voxels z = 7.1 P < .001). Greater physical disability was significantly associated with lower FA in the right posterior cingulum, left callosal splenium, right inferior fronto-occipital fasciculus, and left fornix crus (six studies 323 voxels z = 1.7 P = .001). Impaired cognition was significantly associated with lower FA in the callosal genu, thalamus, right posterior cingulum, and fornix crus (seven studies largest cluster, 980 voxels z = 2.5 P < .001). WM damage is widespread in MS with differential and only minimally overlapping distributions of low FA that relates to physical disability and cognitive impairment. The higher number of clusters of lower FA in relation to cognition and their higher z scores suggest that cerebral WM damage may have a greater relevance to cognitive dysfunction than physical disability in MS, and that low anterior callosal and thalamic FA have specific importance to cognitive status.
Publisher: Elsevier BV
Date: 2019
Publisher: Wiley
Date: 25-10-2019
DOI: 10.1111/ENE.14084
Publisher: Wiley
Date: 26-11-2019
DOI: 10.1002/HBM.24874
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-07-2020
Publisher: Wiley
Date: 04-12-2018
DOI: 10.1002/HBM.24411
Publisher: Springer Science and Business Media LLC
Date: 23-09-2014
Publisher: Mary Ann Liebert Inc
Date: 05-2015
Publisher: Wiley
Date: 29-09-2016
DOI: 10.1002/HBM.23414
Publisher: Frontiers Media SA
Date: 19-05-2020
Publisher: Springer Science and Business Media LLC
Date: 11-11-2021
Publisher: Wiley
Date: 25-11-2019
DOI: 10.1002/HBM.24870
Publisher: Wiley
Date: 10-11-2022
DOI: 10.1002/MRM.29488
Abstract: Click here for author‐reader discussions
Publisher: Springer Science and Business Media LLC
Date: 24-07-2019
DOI: 10.1038/S41398-019-0512-8
Abstract: Reduced gray matter (GM) volume may represent a hallmark of major depressive disorder (MDD) neuropathology, typified by wide-ranging distribution of structural alteration. In the study, we aimed to replicate and extend our previous finding of profound and widespread GM loss in MDD, and evaluate the diagnostic accuracy of a structural biomarker derived from GM volume in an interconnected pattern across the brain. In a sub-study of the International Study to Predict Optimized Treatment in Depression (iSPOT-D), two cohorts of clinically defined MDD participants “Test” ( n = 98) and “Replication” ( n = 131) were assessed alongside healthy controls ( n = 66). Using 3T MRI T1-weighted volumes, GM volume differences were evaluated using voxel-based morphometry. Sensitivity, specificity, and area under the receiver operating characteristic curve were used to evaluate an MDD diagnostic biomarker based on a precise spatial pattern of GM loss constructed using principal component analysis. We demonstrated a highly conserved symmetric widespread pattern of reduced GM volume in MDD, replicating our previous findings. Three bilateral dominant clusters were observed: Cluster 1: midline/cingulate (GM reduction: Test: 6.4%, Replication: 5.3%), Cluster 2: medial temporal lobe (GM reduction: Test: 8.2%, Replication: 11.9%), Cluster 3: prefrontal cortex (GM reduction: Test: 12.1%, Replication: 23.2%). We developed a biomarker reflecting the global pattern of GM reduction, achieving good diagnostic classification performance (AUC: Test = 0.75, Replication = 0.84). This study establishes that a highly specific pattern of reduced GM volume is a feature of MDD, suggestive of a structural basis for this disease. We introduce and validate a novel diagnostic biomarker based on this pattern.
Publisher: Springer Science and Business Media LLC
Date: 25-04-2018
DOI: 10.1038/S41398-018-0140-8
Abstract: Diffusion MRI (dMRI) tractography is a uniquely powerful tool capable of demonstrating structural brain network abnormalities across a range of psychiatric disorders however, it is not currently clinically useful. This is because limitations on sensitivity effectively restrict its application to scientific studies of cohorts, rather than in idual patients. Recent improvements in dMRI hardware, acquisition, processing and analysis techniques may, however, overcome these measurement limitations. We therefore acquired the highest-ever angular resolution in vivo tractographic data set, and used these data to ask the question: 'is cutting-edge, optimised dMRI now sensitive enough to measure brain network abnormalities at a level that may enable personalised psychiatry?' The fibre tracking performance of this 'gold standard' data set of 1150 unique directions (11 shells) was compared to a conventional 64-direction protocol (single shell) and a clinically practical, highly optimised and accelerated 9-min protocol of 140 directions (3 shells). Three major tracts of relevance to psychiatry were evaluated: the cingulate bundle, the uncinate fasciculus and the corticospinal tract. We found up to a 34-fold improvement in tracking accuracy using the 1150-direction data set compared to the 64-direction data set, while 140-direction data offered a maximum 17-fold improvement. We also observed between 20 and 50% improvements in tracking efficiency for the 140-direction data set, a finding we then replicated in a normal cohort ( n = 53). We found evidence that lower angular resolution data may introduce systematic anatomical biases. These data highlight the imminent potential of dMRI as a clinically meaningful technique at a personalised level, and should inform current practice in clinical studies.
Publisher: Cold Spring Harbor Laboratory
Date: 09-07-2023
DOI: 10.1101/2023.07.08.23292404
Abstract: Impaired attention performance is a significant burden to people with multiple sclerosis (MS). Brain connectivity fluctuates with transitions between cognitive states, so measurement of network dynamics during these conditions may help to understand MS-related attention impairment. In people with MS and healthy controls, attention was measured using the Attention Network Test. 3T MRI was used to measure structural connectivity and both static and dynamic functional connectivity in the attention-related fronto-parietal network (FPN) at rest and during an attentionally-demanding task. Groups were compared on connectivity of the FPN during rest and task performance. Relationships between network connectivity and attention performance were tested using linear regression. The s le comprised 37 people with MS and 23 matched controls. At rest, people with MS had significantly lower structural connectivity (R 2 =0.13, p=0.004), lower static functional connectivity (R 2 =0.07, p=0.032) and higher dynamic functional connectivity (R 2 =0.08, p=0.026) of the FPN. Higher dynamic connectivity was significantly associated with poorer attention performance in people with MS (R 2 =0.20, p=0.008). During attention-task performance, static functional connectivity was greater in people with MS than controls (R 2 =0.10, p=0.008). The task-induced reduction in static connectivity (relative to rest) was directly related to attention performance (R 2 =0.23, p .001). Increased dynamic functional connectivity of the FPN at rest may be a useful indicator of deficits in sustained attention in people with MS. The transition from rest to active-attentive state is accompanied by an increase in dynamic connectivity, and decrease in static connectivity which may be helpful in understanding aetiology and treatment of attention impairment.
Publisher: Wiley
Date: 17-01-2021
DOI: 10.1002/MDS.28481
Publisher: Wiley
Date: 10-11-2022
DOI: 10.1002/JMRI.28459
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Thomas Welton.