2 items tagged with 'fdg-pet'.
Abstract (Expand)
During implantation of deep-brain stimulation (DBS) electrodes in the target structure, neurosurgeons and neurologists commonly observe a "microlesion effect" (MLE), which occurs well before … initiating subthalamic DBS. This phenomenon typically leads to a transitory improvement of motor symptoms of patients suffering from Parkinson's disease (PD). Mechanisms behind MLE remain poorly understood. In this work, we exploited the notion of ranking to assess spontaneous brain activity in PD patients examined by resting-state functional magnetic resonance imaging in response to penetration of DBS electrodes in the subthalamic nucleus. In particular, we employed a hypothesis-free method, eigenvector centrality (EC), to reveal motor-communication-hubs of the highest rank and their reorganization following the surgery; providing a unique opportunity to evaluate the direct impact of disrupting the PD motor circuitry in vivo without prior assumptions. Penetration of electrodes was associated with increased EC of functional connectivity in the brainstem. Changes in connectivity were quantitatively related to motor improvement, which further emphasizes the clinical importance of the functional integrity of the brainstem. Surprisingly, MLE and DBS were associated with anatomically different EC maps despite their similar clinical benefit on motor functions. The DBS solely caused an increase in connectivity of the left premotor region suggesting separate pathophysiological mechanisms of both interventions. While the DBS acts at the cortical level suggesting compensatory activation of less affected motor regions, the MLE affects more fundamental circuitry as the dysfunctional brainstem predominates in the beginning of PD. These findings invigorate the overlooked brainstem perspective in the understanding of PD and support the current trend towards its early diagnosis.
Authors: S. Holiga, K. Mueller, H. E. Moller, D. Urgosik, E. Ruzicka, M. L. Schroeter, R. Jech
PubMed ID: 26509113
Citation: Neuroimage Clin. 2015 Aug 21;9:264-74. doi: 10.1016/j.nicl.2015.08.008. eCollection 2015.
Created: 9th May 2019 at 09:38, Last updated: 7th Dec 2021 at 17:58
Abstract (Expand)
INTRODUCTION: Uniform coordinate systems in neuroimaging research have enabled comprehensive systematic and quantitative meta-analyses. Such approaches are particularly relevant for neuropsychiatric … diseases, the understanding of their symptoms, prediction and treatment. Behavioral variant frontotemporal dementia (bvFTD), a common neurodegenerative syndrome, is characterized by deep alterations in behavior and personality. Investigating this 'nexopathy' elucidates the healthy social and emotional brain. METHODS: Here, we combine three multimodal meta-analyses approaches - anatomical and activation likelihood estimates and behavioral domain profiles - to identify neural correlates of bvFTD in 417 patients and 406 control subjects and to extract mental functions associated with this disease by meta-analyzing functional activation studies in the comprehensive probabilistic functional brain atlas of the BrainMap database. RESULTS: The analyses identify the frontomedian cortex, basal ganglia, anterior insulae and thalamus as most relevant hubs, with a regional dissociation between atrophy and hypometabolism. Neural networks affected by bvFTD were associated with emotion and reward processing, empathy and executive functions (mainly inhibition), suggesting these functions as core domains affected by the disease and finally leading to its clinical symptoms. In contrast, changes in theory of mind or mentalizing abilities seem to be secondary phenomena of executive dysfunctions. CONCLUSIONS: The study creates a novel conceptual framework to understand neuropsychiatric diseases by powerful data-driven meta-analytic approaches that shall be extended to the whole neuropsychiatric spectrum in the future.
Authors: M. L. Schroeter, A. R. Laird, C. Chwiesko, C. Deuschl, E. Schneider, D. Bzdok, S. B. Eickhoff, J. Neumann
Date Published: 26th Apr 2014
Publication Type: Not specified
Human Diseases: frontotemporal dementia
PubMed ID: 24763126
Citation: Cortex. 2014 Aug;57:22-37. doi: 10.1016/j.cortex.2014.02.022. Epub 2014 Mar 21.
Created: 9th May 2019 at 08:31, Last updated: 7th Dec 2021 at 17:58