scholarly journals Distributional changes in myelin-specific MRI markers uncover dynamics in the fornix following spatial navigation training

2020 ◽  
Author(s):  
Debbie Anaby ◽  
Benjamin C Tendler ◽  
Matthias S Treder ◽  
Simon Hametner ◽  
Ulrike Koeck ◽  
...  
Keyword(s):  
Diffusion Tensor ◽  
Magnetization Transfer ◽  
Spatial Navigation ◽  
Cellular Mechanisms ◽  
Microstructural Changes ◽  
Microstructural Parameters ◽  
Mature Brain ◽  
Primary Hypothesis

Increasing evidence implicates white matter (WM) dynamics supporting learning in the mature brain. Recent MRI studies, mostly using diffusion tensor MRI (DT-MRI), have demonstrated learning-induced WM changes at the microstructural level. However, while DT-MRI-derived measures have sensitivity to general WM microstructural changes, they lack compartmental specificity, making them difficult to relate to underlying cellular mechanisms, stymying deeper understanding of mechanisms supporting training-induced gains in performance. Gaining a deeper understanding demands a more detailed characterization of changes in specific WM sub-components. To this end, four microstructural MRI techniques were employed to study alterations in rat brains after 5-days of water maze training: DT-MRI; Composite Hindered and Restricted Model of Diffusion (CHARMED); magnetization transfer (MT) imaging; quantitative susceptibility mapping and R2*. The hypothesis tested here was that microstructural changes would be: (i) observed in tracts supporting spatial navigation, i.e., fornix and corpus callosum (CC); and (ii) more pronounced in the myelin-specific measures. Medians and distributions of microstructural parameters were derived along the fornix, CC and cingulum (as a comparison tract) using the ′tractometry′ approach. Summary measures were derived from different metrics using unsupervised data reduction. Significant pre-vs-post training differences were found in the medians of two principal components loading on: (i) anisotropy indices; and (ii) MT ratio. The most striking effect, however, was seen in the distributions of pre-vs-post training MT ratio in the fornix, consistent with the primary hypothesis, and highlighting the value of this alternative to the standard approach (i.e., comparing means/medians of DT-MRI parameters) for studying neuroplasticity in vivo.

In Vivo Characterization of Transport Anisotropy in Rat Spinal Cord Using Diffusion Tensor Imaging

2008 ◽  
Author(s):  
Xiaoming Chen ◽  
Garrett W. Astary ◽  
Thomas H. Mareci ◽  
Malisa Sarntinoranont
Keyword(s):  
Spinal Cord ◽  
Diffusion Tensor Imaging ◽  
Drug Transport ◽  
Diffusion Tensor ◽  
Local Drug Delivery ◽  
Imaging Method ◽  
Rat Spinal Cord ◽  
In Vivo Characterization

Biotransport in nervous tissues is complicated by the existence of neural fibers. These axonal fibers result in inhomogeneous and anisotropic extracellular transport, which complicates the prediction of local drug delivery such as convection-enhanced delivery [1]. Previous studies by our group [4] have shown that by using diffusion tensor imaging (DTI) [2, 3], anisotropic transport in rat spinal cord can be modeled using computational models, and consequently extracellular flows which influence drug transport can be well predicted. In previous studies, DTI-based models used data from an excised and fixed rat spinal cord. In the current study, we extend our DTI study to in vivo measures, and report the in vivo characterization of transport anisotropy in rat spinal cord. The MR imaging method is presented and the DTI data is discussed.

scholarly journals Drumming Motor Sequence Training Induces Apparent Myelin Remodelling in Huntington’s Disease: A Longitudinal Diffusion MRI and Quantitative Magnetization Transfer Study

2020 ◽  
Vol 9 (3) ◽  
pp. 303-320
Author(s):  
Chiara Casella ◽  
Jose Bourbon-Teles ◽  
Sonya Bells ◽  
Elizabeth Coulthard ◽  
Greg D. Parker ◽  
...  
Keyword(s):  
Executive Function ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Diffusion Tensor ◽  
Small Sample Size ◽  
Magnetization Transfer ◽  
Small Sample ◽  
Motor Sequence ◽  
Longitudinal Diffusion ◽  
Microstructural Changes

Background: Impaired myelination may contribute to Huntington’s disease (HD) pathogenesis. Objective: This study assessed differences in white matter (WM) microstructure between HD patients and controls, and tested whether drumming training stimulates WM remodelling in HD. Furthermore, it examined whether training-induced microstructural changes are related to improvements in motor and cognitive function. Methods: Participants undertook two months of drumming exercises. Working memory and executive function were assessed before and post-training. Changes in WM microstructure were investigated with diffusion tensor magnetic resonance imaging (DT-MRI)-based metrics, the restricted diffusion signal fraction (Fr) from the composite hindered and restricted model of diffusion (CHARMED) and the macromolecular proton fraction (MPF) from quantitative magnetization transfer (qMT) imaging. WM pathways linking putamen and supplementary motor areas (SMA-Putamen), and three segments of the corpus callosum (CCI, CCII, CCIII) were studied using deterministic tractography. Baseline MPF differences between patients and controls were assessed with tract-based spatial statistics. Results: MPF was reduced in the mid-section of the CC in HD subjects at baseline, while a significantly greater change in MPF was detected in HD patients relative to controls in the CCII, CCIII, and the right SMA-putamen post-training. Further, although patients improved their drumming and executive function performance, such improvements did not correlate with microstructural changes. Increased MPF suggests training-induced myelin changes in HD. Conclusion: Though only preliminary and based on a small sample size, these results suggest that tailored behavioural stimulation may lead to neural benefits in early HD, that could be exploited for delaying disease progression.

scholarly journals Multi-parametric MRI characterization of healthy human thigh muscles at 3.0 T - relaxation, magnetization transfer, fat/water, and diffusion tensor imaging

2014 ◽  
Vol 27 (9) ◽  
pp. 1070-1084 ◽  
Author(s):  
Ke Li ◽  
Richard D. Dortch ◽  
E. Brian Welch ◽  
Nathan D. Bryant ◽  
Amanda K. W. Buck ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
Diffusion Tensor ◽  
Magnetization Transfer ◽  
Healthy Human ◽  
Thigh Muscles ◽  
3.0 T ◽  
And Diffusion ◽  
Relaxation Magnetization

scholarly journals In vivo diffusion tensor imaging and ex vivo histologic characterization of white matter pathology in a post-status epilepticus model of temporal lobe epilepsy

Epilepsia ◽  
2011 ◽  
Vol 52 (4) ◽  
pp. 841-845 ◽  
Author(s):  
Pieter van Eijsden ◽  
Wim M. Otte ◽  
W. Saskia van der Hel ◽  
Onno van Nieuwenhuizen ◽  
Rick M. Dijkhuizen ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
Status Epilepticus ◽  
White Matter ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Diffusion Tensor ◽  
Ex Vivo ◽  
White Matter Pathology

scholarly journals Characterization of PEBBLEs as a Tool for Real-Time Measurement ofDictyostelium discoideumEndosomal pH

2009 ◽  
Vol 2009 ◽  
pp. 1-4 ◽  
Author(s):  
Everett Moding ◽  
Jessica Hellyer ◽  
Kevin Rank ◽  
Phoebe Lostroh ◽  
Murphy Brasuel
Keyword(s):  
Real Time ◽  
Fluorescent Dyes ◽  
Ion Concentration ◽  
Ph Sensing ◽  
Cellular Mechanisms ◽  
Real Time Measurement ◽  
Endosomal Ph ◽  
Camp Stimulation

The measurement of intracellular ion concentration change is important for understanding the cellular mechanisms for communication. Recently developed nanosensors, (Photonic Explorers for Biomedical use with Biologically Localized Embedding) PEBBLEs, have a number of advantages for measuring ions in cells over established methods using microelectrodes, unbound fluorescent dyes, or NMR. PEBBLE sensors have been shown to work in principle for measuring dynamic ion changes, but few in vivo applications have been demonstrated. We modified the protocol for the fabrication of pH sensing PEBBLEs and developed a protocol for the utilization of these sensors for the monitoring of dynamic pH changes in the endosomes of slime moldDictyostelium discoideum (D. discoideum). Oregon Green 514-CdSe Quantum Dot PEBBLEs were used to measure real-time pH insideD. discoideumendosomes during cAMP stimulation. Endosomal pH was shown to decrease during cAMP signaling, demonstrating a movement of protons into the endosomes ofD. discoideumamoebae.

USPIO-positive MS lesions are associated with greater tissue damage than gadolinium-positive-only lesions during 3-year follow-up

2017 ◽  
Vol 24 (14) ◽  
pp. 1852-1861 ◽  
Author(s):  
Anne Kerbrat ◽  
Benoit Combès ◽  
Olivier Commowick ◽  
Adil Maarouf ◽  
Elise Bannier ◽  
...  
Keyword(s):  
Tissue Damage ◽  
Magnetization Transfer ◽  
Superparamagnetic Iron Oxide ◽  
Magnetization Transfer Ratio ◽  
Microstructural Changes ◽  
Ultrasmall Superparamagnetic Iron Oxide ◽  
Mri Scans ◽  
Magnetic Resonance Imaging Mri

Background: Identifying in vivo the processes that determine lesion severity in multiple sclerosis (MS) remains a challenge. Objectives: To describe the dynamics of ultrasmall superparamagnetic iron oxide (USPIO) enhancement in MS lesions and the relationship between USPIO enhancement and microstructural changes over 3 years. Methods: Lesion development was assessed at baseline, Months 3, 6, and 9, using magnetic resonance imaging (MRI) with gadolinium and USPIO. Microstructural changes were assessed at baseline, Months 3, 6, 9, 12, 18, 24, and 36, using relaxometry, magnetization transfer, and diffusion-weighted imaging. Results: We included 15 patients with clinically isolated syndrome. In the 52 MRI scans acquired with USPIO, 22 lesions were USPIO and gadolinium positive, and 44 were USPIO negative but gadolinium positive. Lesions no longer exhibited sustained USPIO enhancement 3 months later. At baseline, lesions that were both USPIO and gadolinium positive had lower magnetization transfer ratio values (common language effect size = 0.84, p = 0.0005) and lower fractional anisotropy values (0.83, p = 0.001) than gadolinium-positive-only lesions. USPIO-positive lesions remained associated with greater damage than gadolinium-positive-only lesions throughout the 3-year follow-up. Conclusion: USPIO enhancement, mainly reflecting monocyte infiltration, is transient and is associated with persistent tissue damage after 3 years.

scholarly journals Macrophage Identification In Situ

Biomedicines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1393
Author(s):  
Krisztina Nikovics ◽  
Anne-Laure Favier
Keyword(s):  
Tissue Regeneration ◽  
Reporter Genes ◽  
Cellular Mechanisms ◽  
Comprehensive Overview ◽  
Distinctive Features ◽  
Long Time

Understanding the processes of inflammation and tissue regeneration after injury is of great importance. For a long time, macrophages have been known to play a central role during different stages of inflammation and tissue regeneration. However, the molecular and cellular mechanisms by which they exert their effects are as yet mostly unknown. While in vitro macrophages have been characterized, recent progress in macrophage biology studies revealed that macrophages in vivo exhibited distinctive features. Actually, the precise characterization of the macrophages in vivo is essential to develop new healing treatments and can be approached via in situ analyses. Nowadays, the characterization of macrophages in situ has improved significantly using antigen surface markers and cytokine secretion identification resulting in specific patterns. This review aims for a comprehensive overview of different tools used for in situ macrophage identification, reporter genes, immunolabeling and in situ hybridization, discussing their advantages and limitations.

scholarly journals Drumming motor sequence training induces apparent myelin remodelling in Huntington’s disease: a longitudinal diffusion MRI and quantitative magnetization transfer study

2019 ◽  
Author(s):  
Chiara Casella ◽  
Jose Bourbon-Teles ◽  
Sonya Bells ◽  
Elizabeth Coulthard ◽  
Greg D. Parker ◽  
...  
Keyword(s):  
Executive Function ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Diffusion Tensor ◽  
Magnetization Transfer ◽  
Motor Sequence ◽  
Longitudinal Diffusion ◽  
Microstructural Changes ◽  
Before And After ◽  
The Right

1.AbstractBackgroundImpaired myelination may contribute to Huntington’s disease (HD) pathogenesis. This study assessed differences in white matter (WM) microstructure between HD patients and controls, and tested whether drumming training stimulates WM remodelling in HD. Furthermore, it examined whether training-induced microstructural changes are related to improvements in motor and cognitive function.MethodsParticipants undertook two months of drumming exercises. Working memory and executive function were assessed before and after training. Changes in WM microstructure were investigated with diffusion tensor magnetic resonance imaging (DT-MRI)-based metrics, the restricted diffusion signal fraction (Fr) from the composite hindered and restricted model of diffusion (CHARMED) and the macromolecular proton fraction (MPF) from quantitative magnetization transfer (qMT) imaging. WM pathways linking the putamen and the supplementary motor area (SMA-Putamen), and three segments of the corpus callosum (CCI, CCII, CCIII) were studied using deterministic tractography. Baseline MPF differences between patients and controls were assessed with tract-based spatial statistics (TBSS).ResultsMPF was reduced in HD patients compared to controls in the mid-section of the CC in HD subjects at baseline, while a significantly greater change in MPF was detected in HD patients relative to controls in the CCII, CCIII, and the right SMA-putamen post-training. Further, although patients improved their drumming and executive function performance, such improvements did not correlate with microstructural changes.ConclusionsIncreased MPF suggests training-induced myelin changes in HD. Tailored behavioural stimulation may lead to neural benefits in early HD that could be exploited for delaying disease progression.

Sign in / Sign up

Export Citation Format

Share Document