Central nervous tissue: an excitable medium. A study using the retinal spreading depression as a tool

2007 ◽  
Vol 366 (1864) ◽  
pp. 359-368 ◽  
Author(s):  
Wolfgang Hanke ◽  
Vera Maura Fernandes de Lima
Keyword(s):  
Spreading Depression ◽  
Imaging Techniques ◽  
Optical Signal ◽  
Excitable Medium ◽  
Physical Parameters ◽  
Neuronal Tissue ◽  
Retinal Tissue ◽  
Propagating Waves ◽  
The Central Nervous System ◽  
External Forces

According to its physicochemical properties, neuronal tissue, including the central nervous system (CNS) and thus the human brain, is an excitable medium, which consequently exhibits, among other things, self-organization, pattern formation and propagating waves. Furthermore, such systems can be controlled by weak external forces. The spreading depression (SD), a propagating wave of excitation–depression, is such an event, which is additionally linked to a variety of medically important situations, classical migraine being just one example. Especially in retinal tissue, a true part of the CNS, the SD can be observed very easily with the naked eye and by video imaging techniques due to its big intrinsic optical signal. We have investigated the retinal SD and its control by external physical parameters such as gravity and temperature. Beyond this, especially due to its medical relevance, the control of CNS excitability by pharmacological tools is of specific interest, and we have studied this question in detail using the retinal SD as an experimental tool to collect information about the control of CNS tissue excitability.

scholarly journals Cell swelling increases the severity of spreading depression in Locusta migratoria

2015 ◽  
Vol 114 (6) ◽  
pp. 3111-3120 ◽  
Author(s):  
Kristin E. Spong ◽  
Brittany Chin ◽  
Kelsey L. M. Witiuk ◽  
R. Meldrum Robertson
Keyword(s):  
Spreading Depression ◽  
Locusta Migratoria ◽  
Cell Swelling ◽  
Extracellular Potassium ◽  
Potassium Ions ◽  
Extracellular Compartment ◽  
Propagating Waves ◽  
The Central Nervous System ◽  
Progressive Accumulation ◽  
Increased Susceptibility

Progressive accumulation of extracellular potassium ions can trigger propagating waves of spreading depression (SD), which are associated with dramatic increases in extracellular potassium levels ([K+]o) and arrest in neural activity. In the central nervous system the restricted nature of the extracellular compartment creates an environment that is vulnerable to disturbances in ionic homeostasis. Here we investigate how changes in the size of the extracellular space induced by alterations in extracellular osmolarity affect locust SD. We found that hypotonic exposure increased susceptibility to experimentally induced SD evidenced by a decrease in the latency to onset and period between individual events. Hypertonic exposure was observed to delay the onset of SD or prevent the occurrence altogether. Additionally, the magnitude of extracellular K+ concentration ([K+]o) disturbance during individual SD events was significantly greater and they were observed to propagate more quickly under hypotonic conditions compared with hypertonic conditions. Our results are consistent with a conclusion that hypotonic exposure reduced the size of the extracellular compartment by causing cell swelling and thus facilitated the accumulation of K+ ions. Lastly, we found that pharmacologically reducing the accumulation of extracellular K+ using the K+ channel blocker tetraethylammonium slowed the rate of SD propagation while increasing [K+]o through inhibition of the Na-K-2Cl cotransporter increased propagation rates. Overall our findings indicate that treatments or conditions that act to reduce the accumulation of extracellular K+ help to protect against the development of SD and attenuate the spread of ionic disturbance adding to the evidence that diffusion of K+ is a leading event during locust SD.

Sub-basalt Marchenko imaging with offshore Brazil field data

Geophysics ◽  
2021 ◽  
pp. 1-47
Author(s):  
Xueyi Jia ◽  
Anatoly Baumstein ◽  
Charlie Jing ◽  
Erik Neumann ◽  
Roel Snieder
Keyword(s):  
Seismic Waves ◽  
Mode Conversion ◽  
Imaging Techniques ◽  
Hydrocarbon Exploration ◽  
Sampled Data ◽  
Geological Interpretation ◽  
Propagating Waves ◽  
Seismic Acquisition ◽  
Internal Multiples ◽  
Multiple Elimination

Sub-basalt imaging for hydrocarbon exploration faces challenges with the presence of multiple scattering, attenuation and mode-conversion as seismic waves encounter highly heterogeneous and rugose basalt layers. A combination of modern seismic acquisition that can record densely-sampled data, and advanced imaging techniques make imaging through basalt feasible. Yet, the internal multiples, if not properly handled during seismic processing, can be mapped to reservoir layers by conventional imaging methods, misguiding geological interpretation. Traditional internal multiple elimination methods suffer from the requirement of picking horizons of multiple generators and/or a top-down adaptive subtraction process. Marchenko imaging provides an alternative solution to directly remove the artifacts due to internal multiples, without the need of horizon picking or subtraction. In this paper, we present a successful application of direct Marchenko imaging for sub-basalt de-multiple and imaging with an offshore Brazil field dataset. The internal multiples in this example are generated from the seabed and basalt layers, causing severe artifacts in conventional seismic images. We demonstrate that these artifacts are largely suppressed with Marchenko imaging and propose a general work flow for data pre-processing and regularization of marine streamer datasets. We show that horizontally propagating waves can also be reconstructed by the Marchenko method at far offsets.

scholarly journals Brain-Derived Neurotrophic Factor and Diabetes

2020 ◽  
Vol 21 (3) ◽  
pp. 841 ◽  
Author(s):  
Olga Rozanska ◽  
Aleksandra Uruska ◽  
Dorota Zozulinska-Ziolkiewicz
Keyword(s):  
Neurotrophic Factor ◽  
Brain Function ◽  
Clinical Problem ◽  
Brain Derived Neurotrophic Factor ◽  
Chronic Complications ◽  
Neuronal Tissue ◽  
Beneficial Impact ◽  
The Central Nervous System ◽  
And Function ◽  
Made In

Diabetes and its chronic complications still represent a great clinical problem, despite improvements made in the diagnosis and treatment of the disease. People with diabetes have a much higher risk of impaired brain function and psychiatric disorders. Neurotrophins are factors that protect neuronal tissue and improve the function of the central nervous system, and among them is brain-derived neurotrophic factor (BDNF). The level and function of BDNF in diabetes seems to be disturbed by and connected with the presence of insulin resistance. On the other hand, there is evidence for the highly beneficial impact of physical activity on brain function and BDNF level. However, it is not clear if this protective phenomenon works in the presence of diabetes. In this review, we summarize the current available research on this topic and find that the results of published studies are ambiguous.

scholarly journals Primary Angiitis of the Central Nervous System: New Potential Imaging Techniques and Biomarkers in Blood and Cerebrospinal Fluid

2019 ◽  
Vol 10 ◽  
Author(s):  
Milani Deb-Chatterji ◽  
Simon Schuster ◽  
Vivien Haeussler ◽  
Christian Gerloff ◽  
Götz Thomalla ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Cerebrospinal Fluid ◽  
Nervous System ◽  
Imaging Techniques ◽  
Primary Angiitis ◽  
The Central Nervous System

Peri-infarct temporal changes in intrinsic optical signal during spreading depression in focal ischemic rat cortex

2007 ◽  
Vol 424 (2) ◽  
pp. 133-138 ◽  
Author(s):  
Zhen Wang ◽  
Pengcheng Li ◽  
Weihua Luo ◽  
Shangbin Chen ◽  
Qingming Luo
Keyword(s):  
Spreading Depression ◽  
Optical Signal ◽  
Temporal Changes ◽  
Rat Cortex ◽  
Intrinsic Optical Signal

scholarly journals Is Crush Cytology of Central Nervous System Lesions Relevant in Surgical Practice Today?

2019 ◽  
Vol 10 (01) ◽  
pp. 34-38 ◽  
Author(s):  
Krishan Kumar Yadav ◽  
Rashmi Bhatti ◽  
Nikhil Moorchung ◽  
Deepti Mutreja ◽  
Ajay S. Carvalho
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Imaging Techniques ◽  
Diagnostic Technique ◽  
High Grade ◽  
Surgical Practice ◽  
The Central Nervous System ◽  
Cns Lesions ◽  
Neurosurgical Intervention

ABSTRACT Background: Intraoperative crush cytology is a useful tool for diagnosing the lesions of the central nervous system (CNS). However, because of the development of newer and better imaging techniques, it is important to evaluate if crush cytology is still relevant in neurosurgical practice. Aims: We evaluated the crush cytology smears in a series of cases where neurosurgical intervention was performed. We studied the role of crush cytology in the intraoperative diagnosis. We report a series of cases where intraoperative crush cytology helped the surgeon revise the surgery during the operation. Materials and Methods: A small portion of all CNS lesions was taken intraoperatively and the tissue was crushed between two slides. The slide was stained using the toluidine blue, Leishman stain, Pap stain and a routine H & E stain. The slides were the evaluated. Results: We evaluated the 50 cases of CNS lesions. We found that intraoperative crush cytology is particularly important in differentiating between neoplastic and nonneoplastic CNS lesions. It may also help in differentiating lymphomas from high-grade gliomas. Finally, crush cytology may help the surgeon in delineating the lesions during surgery. Conclusion: We conclude that crush cytology remains relevant in neurosurgical practice today and it should be adopted in all neurosurgical centers as a routine diagnostic technique.

scholarly journals Diffuse retro-reflective imaging for improved video tracking of mosquitoes at human baited bednets

2020 ◽  
Vol 7 (5) ◽  
pp. 191951 ◽  
Author(s):  
Vitaly Voloshin ◽  
Christian Kröner ◽  
Chandrabhan Seniya ◽  
Gregory P. D. Murray ◽  
Amy Guy ◽  
...  
Keyword(s):  
Large Scale ◽  
Imaging Techniques ◽  
Field Studies ◽  
Noise Removal ◽  
Optical Signal ◽  
Video Tracking ◽  
Ease Of Use ◽  
Model Systems ◽  
Mosquito Behaviour ◽  
Set Up

Robust imaging techniques for tracking insects have been essential tools in numerous laboratory and field studies on pests, beneficial insects and model systems. Recent innovations in optical imaging systems and associated signal processing have enabled detailed characterization of nocturnal mosquito behaviour around bednets and improvements in bednet design, a global essential for protecting populations against malaria. Nonetheless, there remain challenges around ease of use for large-scale in situ recordings and extracting data reliably in the critical areas of the bednet where the optical signal is attenuated. Here, we introduce a retro-reflective screen at the back of the measurement volume, which can simultaneously provide diffuse illumination, and remove optical alignment issues while requiring only one-sided access to the measurement space. The illumination becomes significantly more uniform, although noise removal algorithms are needed to reduce the effects of shot noise, particularly across low-intensity bednet regions. By systematically introducing mosquitoes in front of and behind the bednet in laboratory experiments, we are able to demonstrate robust tracking in these challenging areas. Overall, the retro-reflective imaging set-up delivers mosquito segmentation rates in excess of 90% compared to less than 70% with backlit systems.

Chemically Induced Myelinopathies

1998 ◽  
Vol 17 (3) ◽  
pp. 231-275 ◽  
Author(s):  
Marciavan Gemert ◽  
James Killeen
Keyword(s):  
Nervous System ◽  
Oxidative Phosphorylation ◽  
Peripheral Nervous System ◽  
Cholesterol Synthesis ◽  
Fluid Pressure ◽  
Neuronal Tissue ◽  
Chemically Induced ◽  
The Central Nervous System ◽  
The Brain ◽  
Increased Pressure

The diverse, structurally unrelated chemicals that cause toxic myelinopathies have been investigated and can be categorized into two types of primary demyelinators. Some demyelinating chemicals seem to leave intact the myeli-nating cells (oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system), while others damage the myelinating cells as well as the myelin. The significance between the two is that with the myelinating cells still in tact, repair of the myelin sheath can occur. However, if the myelinating cells are destroyed, repair and reversal of the neuropathy may not occur. Histologically, these chemicals produce an edema of the white matter of the brain, and in some cases the peripheral nervous system, that appears spongy by light microscopy. By electron microscopy, vacuoles can be seen in the myelin surrounding axons. These vacuoles are characterized as fluid-filled separations (splitting) of myelin lamellae at the intraperiod line. In some cases these vacuoles can degenerate further to full demyelination, affecting conduction through those axons. Regeneration of the myelin layers can occur, and in some cases occurs at the same time other axons are undergoing toxic demyelination. Several of these chemicals, however, have been shown to increase cerebrospinal fluid pressure in the brain, optic nerve, and spinal cord, and/or intraneuronal pressure in the perineurium surrounding the axons in the peripheral nervous system. This increased pressure has been correlated with decreased conduction capacity through the axon, ischemia to the neuronal tissue from decreased blood flow because of pressure against the blood vessels, and, if unrelieved, permanent axonal damage. Several of these chemicals havebeen shown to inhibit oxidative phosphorylation, while others uncouple oxidative phosphorylation. One chemical appears to inhibit an enzyme critical to cholesterol synthesis, thus destabilizing myelin. Another hypothesis for a mechanism of action may be in the ability of these compounds to alter membrane permeability.

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