Dynamic Relationship Between Neurostimulation and N-Acetylaspartate Metabolism in the Human Visual Cortex

Baslow, Morris H.; Hrabě, Jan; Guilfoyle, David N.

doi:10.1007/s12031-007-0049-9

Cited by 59 publications

(72 citation statements)

References 34 publications

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“…This pattern confirms the activity of demyelination, as it is observed in other demyelinating diseases and testifies to a deep morphofunctional rearrangement of neural conductors by the type of segmental demyelination [7]. It should be noted that demyelination is characterized by a morphological sign of ESDM of any genesis [2,8,15] and underlies convulsions [1,3].…”

supporting

confidence: 75%

“…Особливу увагу привернули питання про роль мікроциркуляторних змін у розвитку пристосувально-компенсаторних або деструктивних процесів у залежності від глибини патоморфологічних перебудов підшлункової залози [1,2,3,6,11]. Проте, дотепер не було здійснено комплексного морфологічного дослідження різних моделей панкреатиту з урахуванням паренхіматозних змін у залозі, стану мікроциркуляції в органі та їх взаємодії на ультраструктурному рівні.…”

Section: ультраструктрні зміни гемомікроциркуляції та паренхіми підшлunclassified

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Morphological and Functional Changes of Masticatory Muscle Neuromuscular Junctions in the Later Periods of Streptozotocin Diabetes Mellitus Course

Zhurakivska

Grad

Pоpеl

et al. 2017

WOMAB

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The work is devoted to the study of morphofunctional changes of neuromuscular junctions (NMJ) and their hemocirculatory circulation in streptozotocin diabetes mellitus (SDM). Histological and electron microscopic methods of investigation were used. It was established that the SDM for 56-70 days of the course leads to the destruction of most NMJs, which is morphometrically expressed in the decrease of their area. In efferent preterminal nerve fibers, axonal atrophy occurs and partial degeneration of the myelin sheath. At the ultra-structural level, there is a violation of the fine architectonics of neuromuscular synapses, namely, a decrease in the area, the length of the synaptic contact, the number of synaptic vesicles, the number of folds of the postsynaptic membrane, and the distance between them. Such changes in NMJ occur on the background of the development of diabetic microangiopathy and, as a result, lead to a violation of the conductivity of nerve fibers in the masticatory muscle and the excitability of muscle fibers, as evidenced by the data of electroneuromyography of the ENMG. According to ENMG data, with the duration of experimental diabetes of 56-70 days, the axonal polyneuropathy was detected in 6 animals, the other 4 had an axonal-demyelinating polyneuropathy. In this case, only in 9.5% of cases the duration of the motor unit potentials decreases, but in 64.5% of cases the amplitude of the oscillations decreases (p <0.05), which indicates a rapid rate of destruction of NMJ in decompensated experimental DM.

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supporting

confidence: 75%

Section: ультраструктрні зміни гемомікроциркуляції та паренхіми підшлunclassified

Morphological and Functional Changes of Masticatory Muscle Neuromuscular Junctions in the Later Periods of Streptozotocin Diabetes Mellitus Course

Zhurakivska

Grad

Pоpеl

et al. 2017

WOMAB

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confidence: 99%

Letter to the Editor

Mangia

Tkáč

2008

J Mol Neurosci

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We have read with interest the recent publication "Dynamic relationship between neurostimulation and N-acetylaspartate metabolism in the human visual cortex: evidence that NAA functions as a molecular water pump during visual stimulation", by Baslow et al. (2007). The main finding of that paper was a significant 13% decrease of the N-acetylaspartate (NAA) signal during prolonged visual stimulations, as measured by 1 H NMR spectroscopy (MRS) at 3 T. The authors used these results as experimental evidence to support the hypothesis that NAA functions like a "molecular water pump" during increased neuronal activity. We acknowledge and appreciate the effort of the authors to investigate the functional role of NAA during activation by means of MRS. Undoubtedly, the possibility to reveal changes of metabolite concentrations non-invasively during functional paradigms is very promising for neuroscience and neurochemistry research, as it opens a new window for the investigation of brain function and metabolism in either healthy or pathological conditions.The main reason of writing this letter is the fact that experimental data reported in the aforementioned paper by Baslow et al. are in contradiction with our observations published recently in JCBFM (Mangia et al. 2007). In our functional MRS study, we utilized a visual stimulation paradigm, which was very similar to the one used by Baslow and his coworkers, but our MRS experiments were performed at 7 T instead of 3 T. Increased sensitivity and chemical shifts dispersion at 7 T in combination with advanced localization technique and data analysis enabled reliable quantification of 17 brain metabolites during the stimulation paradigm. Off all 17 metabolites, minute (∼0.2 μmol/g) but significant changes were observed only for aspartate, glucose, glutamate, and lactate. The temporal changes found for these four metabolites were proven by difference spectra (Fig. 4 in Mangia et al. 2007). Using data from 12 subjects clearly demonstrated that NAA concentration did not change more than ±0.2%. Given the detection sensitivity at 7 T, changes of NAA in a range of 10% should be observable after one single scan without averaging (SNR=20-25). The only effect we observed on the resonance of NAA at 2.01 ppm was a small increase of the signal height (~2%) but not of the integral (Mangia et al. 2007). This line narrowing was caused by the blood oxygen level dependent effect and was discernible on all strong resonances in the spectrum. Some minor differences in the experimental setup exist between our study and Baslow's study. We used 6-ms echo time (TE) for acquiring spectra from 8.8-ml voxel localized in the primary visual cortex (occipital lobe), while Baslow et al. used 135-ms TE to acquire spectra from 8-ml voxel localized in the "left brain hemisphere." Neither the different echo times nor the different locations of the voxel can explain the different findings, provided that the selected areas underwent increased neuronal activity during the stimuli. In addition, different methods of...

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“…In healthy subjects, there is an increase in NAA in gray matter from ventral to dorsal, and from the cerebral hemispheres to the spinal cord (Pouwels and Frahm, 1998). Several studies suggest NAA to be a brain osmolyte with possible reversible changes (Baslow et al, 2003(Baslow et al, , 2007Moffett et al, 2007). It is considered as a marker of neuronal density and viability and functional status (Ebisu et al, 1994;Sullivan et al, 2001); its peak decrease when there is neuron suffering or loss.…”

Section: Magnetic Resonance Spectroscopy Protocolmentioning

confidence: 99%

Magnetic resonance spectroscopy and diffusion tensor imaging in coma survivors: promises and pitfalls

Tshibanda

Vanhaudenhuyse

Galanaud

et al. 2009

Progress in Brain Research

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The status of comatose patient is currently established on the basis of the patient-exhibited behaviors. Clinical assessment is subjective and, in 40% of patients, fails to distinguish vegetative state (VS) from minimally conscious states (MCS). The technologic advances of magnetic resonance imaging (MRI) have dramatically improved our understanding of these altered states of consciousness. The role of neuroimaging in coma survivors has increased beyond the simple evaluation of morphological abnormalities. The development of 1H-MR spectroscopy (MRS) and diffusion tensor imaging (DTI) provide opportunity to evaluate processes that cannot be approached by current morphologic MRI sequences. They offer potentially unique insights into the histopathology of VS and MCS. The MRS is a powerful noninvasive imaging technique that enables the in vivo quantification of certain chemical compound or metabolites as N-acetylaspartate (NAA), Choline (Cho), and Creatine (Cr). These biomarkers explore neuronal integrity (NAA), cell membrane turnover (Cho), and cell energetic function (Cr). DTI is an effective and proved quantitative method for evaluating tissue integrity at microscopic level. It provides information about the microstructure and the architecture of tissues, especially the white matter. Various physical parameters can be extracted from this sequence: the fractional anisotropy (FA), a marker of white matter integrity; mean diffusivity (MD); and the apparent diffusion coefficient (ADC) which can differentiate cytotoxic and vasogenic edema. The most prominent findings with MRS and DTI performed in traumatic brain-injured (TBI) patients in subacute phase are the reduction of the NAA/Cr ratio in posterior pons and the decrease of mean infratentorial and supratentorial FA except in posterior pons that enables to predict unfavorable outcome at 1 year from TBI with up to 86% sensitivity and 97% specificity. This review will focus on the interest of comatose patients MRI multimodal assessment with $ Luaba Tshibanda and Audrey Vanhaudenhuyse contributed equally to this work.

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Dynamic Relationship Between Neurostimulation and N-Acetylaspartate Metabolism in the Human Visual Cortex

Cited by 59 publications

References 34 publications

Morphological and Functional Changes of Masticatory Muscle Neuromuscular Junctions in the Later Periods of Streptozotocin Diabetes Mellitus Course

Morphological and Functional Changes of Masticatory Muscle Neuromuscular Junctions in the Later Periods of Streptozotocin Diabetes Mellitus Course

Letter to the Editor

Magnetic resonance spectroscopy and diffusion tensor imaging in coma survivors: promises and pitfalls

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