scholarly journals Modulation of intercolumnar synchronization by endogenous electric fields in cerebral cortex

2021 ◽  
Vol 7 (10) ◽  
pp. eabc7772
Author(s):  
Beatriz Rebollo ◽  
Bartosz Telenczuk ◽  
Alvaro Navarro-Guzman ◽  
Alain Destexhe ◽  
Maria V. Sanchez-Vives
Keyword(s):  
Cerebral Cortex ◽  
Electric Fields ◽  
Rhythmic Activity ◽  
Cortical Columns ◽  
Mediated Effects ◽  
Cortical Oscillations ◽  
Dipole Interactions ◽  
Electric Dipoles ◽  
The Brain

Neurons synaptically interacting in a conductive medium generate extracellular endogenous electric fields (EFs) that reciprocally affect membrane potential. Exogenous EFs modulate neuronal activity, and their clinical applications are being profusely explored. However, whether endogenous EFs contribute to network synchronization remains unclear. We analyzed spontaneously generated slow-wave activity in the cerebral cortex network in vitro, which allowed us to distinguish synaptic from nonsynaptic mechanisms of activity propagation and synchronization. Slow oscillations generated EFs that propagated independently of synaptic transmission. We demonstrate that cortical oscillations modulate spontaneous rhythmic activity of neighboring synaptically disconnected cortical columns if layers are aligned. We provide experimental evidence that these EF-mediated effects are compatible with electric dipoles. With a model of interacting dipoles, we reproduce the experimental measurements and predict that endogenous EF–mediated synchronizing effects should be relevant in the brain. Thus, experiments and models suggest that electric-dipole interactions contribute to synchronization of neighboring cortical columns.

Syzygium cumini (L.) skeels seed extract ameliorates in vitro and in vivo oxidative potentials of the brain cerebral cortex of alcohol-treated rats

2011 ◽  
Vol 12 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Shahdat Hossain ◽  
Asiqur Rahaman ◽  
Taslima Nahar ◽  
Mafroz Ahmed Basunia ◽  
Ferdousi Rahman Mowsumi ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Seed Extract ◽  
Syzygium Cumini ◽  
The Brain

PROGESTIN BINDING IN VITRO BY THE BRAIN CELL NUCLEI OF OVARIECTOMIZED OESTROGEN-PRIMED RATS

1979 ◽  
Vol 82 (3) ◽  
pp. 347-NP ◽  
Author(s):  
K. SEIKI ◽  
Y. HARUKI ◽  
Y. IMANISHI ◽  
T. ENOMOTO
Keyword(s):  
Cerebral Cortex ◽  
Sucrose Density Gradient ◽  
Brain Cell ◽  
Nuclear Fraction ◽  
Cell Nuclei ◽  
Medial Basal Hypothalamus ◽  
Similar Preparation ◽  
The Brain ◽  
Binding Component

The uptake and binding of 17α,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione, a synthetic progestin, by the hypothalamus and cerebral cortex of ovariectomized oestrogen-primed rats was examined in vitro. Uptake of this steroid by the medial basal hypothalamus was higher than that by the remaining hypothalamus and cerebral cortex. The component in the cytosol from whole hypothalami which bound the radioactive progestin sedimented in the 7S region when centrifuged in a sucrose density gradient. The tritiated progestin was displaced by incubation with non-radioactive progestin or progesterone but not by oestradiol-17β, corticosterone or 5α-dihydrotestosterone (1 μmol/l). No 7S binding component was detected in a similar preparation from the cerebral cortex. The nuclear fraction from whole hypothalami extracted by KCl (0·4 mol/l) contained a progestin-binding complex which sedimented at 9S and which was heat-labile and protein in nature. It was concluded that the hypothalamus of ovariectomized oestrogen-primed rats contains progestin-binding material in the cytoplasm and progestin, bound to such material, is transported from the cytoplasm to the nucleus.

scholarly journals Differences in the molecular structure of the blood-brain barrier in the cerebral cortex and white matter: an in silico, in vitro, and ex vivo study

2016 ◽  
Vol 310 (11) ◽  
pp. H1702-H1714 ◽  
Author(s):  
Ádám Nyúl-Tóth ◽  
Maria Suciu ◽  
Judit Molnár ◽  
Csilla Fazakas ◽  
János Haskó ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cerebral Cortex ◽  
White Matter ◽  
Blood Brain Barrier ◽  
In Silico ◽  
Grey Matter ◽  
Ex Vivo ◽  
Cortical Grey Matter ◽  
The Brain

The blood-brain barrier (BBB) is the main interface controlling molecular and cellular traffic between the central nervous system (CNS) and the periphery. It consists of cerebral endothelial cells (CECs) interconnected by continuous tight junctions, and closely associated pericytes and astrocytes. Different parts of the CNS have diverse functions and structures and may be subject of different pathologies, in which the BBB is actively involved. It is largely unknown, however, what are the cellular and molecular differences of the BBB in different regions of the brain. Using in silico, in vitro, and ex vivo techniques we compared the expression of BBB-associated genes and proteins (i.e., markers of CECs, brain pericytes, and astrocytes) in the cortical grey matter and white matter. In silico human database analysis (obtained from recalculated data of the Allen Brain Atlas), qPCR, Western blot, and immunofluorescence studies on porcine and mouse brain tissue indicated an increased expression of glial fibrillary acidic protein in astrocytes in the white matter compared with the grey matter. We have also found increased expression of genes of the junctional complex of CECs (occludin, claudin-5, and α-catenin) in the white matter compared with the cerebral cortex. Accordingly, occludin, claudin-5, and α-catenin proteins showed increased expression in CECs of the white matter compared with endothelial cells of the cortical grey matter. In parallel, barrier properties of white matter CECs were superior as well. These differences might be important in the pathogenesis of diseases differently affecting distinct regions of the brain.

scholarly journals Regional distribution of the enzymes of haem biosynthesis and the inhibition of 5-aminolaevulinate synthase by manganese in the rat brain

1980 ◽  
Vol 190 (2) ◽  
pp. 315-321 ◽  
Author(s):  
Mahin D. Maines
Keyword(s):  
Enzyme Activity ◽  
Cerebral Cortex ◽  
Rat Brain ◽  
Metal Ion ◽  
Regional Distribution ◽  
State Level ◽  
Haem Biosynthesis ◽  
The Brain

The activity of 5-aminolaevulinate synthase, the rate-limiting enzyme of haem biosynthesis, is differentially distributed in various regions of the rat brain. The cerebellum possessed the highest enzyme activity of the eight regions studied. The cerebral cortex and the midbrain also exhibited high 5-aminolaevulinate synthase activity; the septum, hypothalamus, thalamus, amygdala and the hippocampus possessed much lower enzyme activity. However, the total porphyrin and haem contents of the different brain segments did not vary greatly. Mn2+, when administered subcutaneously to rats, effectively inhibited the activity of 5-aminolaevulinate synthase in the cerebellum, midbrain and cerebral cortex; however, repeated injections of the metal ion neither decreased the haem and porphyrin contents of the brain nor induced haem oxygenase activity. Mn2+ was not an effective inhibitor of 5-aminolaevulinate synthase activity in vitro. On the other hand, studies carried out with the liver in vivo suggested that Mn2+ may alter the turnover rate of cellular haem and haemoproteins. In that event, it is likely that the inhibition of 5-aminolaevulinate synthase by Mn2+ was in part a result of the inhibition of protein synthesis by the metal ion. It is postulated that the haem and porphyrin contents of the brain are maintained at a steady-state level, due in part to the refractoriness to inducers of the regulatory mechanism for haem catabolic enzymes and in part to the ability of the organ to utilize haem precursors derived from extraneuronal sources.

scholarly journals The effect of thyroxine isomers on the processes of free radical oxidation in the subcellular fractions of the rat cerebral cortex

2000 ◽  
Vol 46 (4) ◽  
pp. 32-34
Author(s):  
O. V. Galkina ◽  
V. M. Prokopenko ◽  
F. E. Putilina ◽  
N. D. Yeshchenko ◽  
A. V. Arutyunyan
Keyword(s):  
Cerebral Cortex ◽  
Free Radical ◽  
Free Radical Oxidation ◽  
Mitochondrial Fraction ◽  
Rat Cerebral Cortex ◽  
Radical Oxidation ◽  
Adult Rat ◽  
Synaptosomal Fraction ◽  
The Brain

Effective concentrations for D and L thyroxin isomers were determined by the chemiluminescent (CL) method and their effects on free radical oxidation in the mitochondrial and synaptosomal fraction of adult rat cerebral cortex were studied in vitro. A OA DT4 in a model system with riboflavin was 2.2 times higher than L-T4. Effective concentrations for both thyroxin forms were 1$q= = 7.43 x 10~5+/-0.71 M for D-T4 and 15q=15.47 x 10~5+/1.23 M for L-T4. Thyroxin effect on membranous fraction of the brain cortex was studied in vitro using luminol-dependent peroxide CL. In normal concentrations (1 x 108 M) both hormone forms exerted equally intensive antioxidant effect which was more pronounced in the mitochondrial fraction, where CL decreased by 69 and 66%, while in the synaptosomal fraction it decreased only by 45 and 46%. Since D form possesses no hormonal activity, this effect may be due to phenol origin of thyroxin.  

Epileptiform activity in the dentate gyrus during low-calcium perfusion and exposure to transient electric fields

1995 ◽  
Vol 74 (1) ◽  
pp. 388-399 ◽  
Author(s):  
T. L. Richardson ◽  
C. N. O'Reilly
Keyword(s):  
Dentate Gyrus ◽  
Electric Fields ◽  
Field Intensity ◽  
Applied Field ◽  
Granule Cells ◽  
Epileptiform Activity ◽  
Rhythmic Activity ◽  
Experimental Models ◽  
Average Field

1. The dentate gyrus fails to develop epileptiform activity in many experimental models of epilepsy, including the in vitro low-Ca2+ model. Although manipulating the K+ concentration or osmolality of normal low-Ca2+ perfusion mediums can enhance the propensity of the dentate gyrus to develop seizure activity, the specific mechanisms contributing to this change are still under investigation. Identification of these mechanisms should improve our understanding of epileptogenesis and of the factors contributing to the propensity for seizure discharge in other tissues. 2. In the present experiments we used externally generated electric fields to depolarize the somata of large populations of dentate granule cells during exposure to a perfusion medium with no added Ca2+ (low-Ca2+ medium). Uniform electric fields were generated across an individual slice by passing current between two parallel AgCl-coated silver wires placed on the surface of the artificial cerebral spinal fluid. The wires were positioned to straddle the slice such that the current flow was parallel to the dendrosomatic axis of the cell population under investigation. 3. Under control conditions (low-Ca2+ medium, no applied field), stimulation of the dentate hilus evoked a single antidromic population spike in 89% of the slices studied (n = 27). During application of electric fields the same stimulus evoked epileptiform activity in all trials. Well-formed bursts first occurred at an average field intensity of +22.9 +/- 2.5 (SE) mV/mm (n = 24). The amplitude of individual spikes and the total number of spikes, within a burst increased in a graded fashion as the magnitude of the applied field was increased. 4. High field intensities evoked epileptiform activity in the absence of a synchronizing antidromic stimulus. These field-induced bursts occurred after a progressive buildup of rhythmic activity recorded in the extrasomatic space and could persist for the entire duration of an applied field, lasting for several seconds. The average field intensity required to produce a threshold burst was +84.6 +/- 3.6 mV/mm (n = 24). 5. In 11% of trials (3 of 27) the dentate gyrus exhibited poorly developed antidromic bursting without the application of depolarizing electric fields. These bursts were completely suppressed by hyperpolarizing fields in the range of -10 to -20 mV/mm. 6. The results of this investigation support the hypothesis that granule cell sensitivity to nonsynaptic interactions is adequate to support bursting in a normal low-Ca2+ medium, but bursting fails to occur because these cells are normally too hyperpolarized relative to their action potential threshold.(ABSTRACT TRUNCATED AT 400 WORDS)

Biochemische Untersuchungen an experimentell chronisch epileptischen Tieren / Biochemical Investigations of Experimental Chronic Epileptic Animals

1971 ◽  
Vol 26 (11) ◽  
pp. 1158-1167 ◽  
Author(s):  
Eberhard Riedel ◽  
Eugen Wamsiedler
Keyword(s):  
Cerebral Cortex ◽  
Gray Matter ◽  
Brain Metabolism ◽  
Tissue Respiration ◽  
Good Reproducibility ◽  
Chronic Epilepsy ◽  
Alumina Gel ◽  
Gel Injection ◽  
The Brain

In the brain-metabolism of experimental chronic epileptic cats (modificated Kopeloffmethod of intracerebrale alumina-gel injection) some alterations were observed in the lesioned cortical hemisphere. An increase of tissue-respiration in vitro (gray-matter of the cerebral cortex), increase of the activities of alkaline (E.C. 3.1.3.1) and acid phosphomonoesterases (E.C. 3.1.3.2) and a decrease of K-Na-stimulated, Ouabain-inhibited adenosintriphosphatase (E.C. 3.6.1.3) were determined. Postconvulsive (one to six hours after seizures) these changes were found to be more extensive than one or more days after discharge. They couldn’t be found in brain tissues of cats only with mechanical lesions without injection of aluminagel2 which didn’t have convulsions. Because the good reproducibility the communicated method for experimental chronic epilepsy is proposed for pharmacological investigations.

Glucuronyl 3-sulfate occurs exclusively on distal unmyelinated terminals of selected sensory neurons in the peripheral nervous system

1995 ◽  
Vol 53 ◽  
pp. 958-959
Author(s):  
S.S. Spicer ◽  
B.A. Schulte
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Cerebral Cortex ◽  
Peripheral Nervous System ◽  
Sensory Neurons ◽  
Sensory Nerves ◽  
Tissue Antigens ◽  
The Central Nervous System ◽  
The Brain ◽  
Leu 7

Generation of monoclonal antibodies (MAbs) against tissue antigens has yielded several (VC1.1, HNK- 1, L2, 4F4 and anti-leu 7) which recognize the unique sugar epitope, glucuronyl 3-sulfate (Glc A3- SO4). In the central nervous system, these MAbs have demonstrated Glc A3-SO4 at the surface of neurons in the cerebral cortex, the cerebellum, the retina and other widespread regions of the brain.Here we describe the distribution of Glc A3-SO4 in the peripheral nervous system as determined by immunostaining with a MAb (VC 1.1) developed against antigen in the cat visual cortex. Outside the central nervous system, immunoreactivity was observed only in peripheral terminals of selected sensory nerves conducting transduction signals for touch, hearing, balance and taste. On the glassy membrane of the sinus hair in murine nasal skin, just deep to the ringwurt, VC 1.1 delineated an intensely stained, plaque-like area (Fig. 1). This previously unrecognized structure of the nasal vibrissae presumably serves as a tactile end organ and to our knowledge is not demonstrable by means other than its selective immunopositivity with VC1.1 and its appearance as a densely fibrillar area in H&E stained sections.

Effect of pH and inhibitors on beta-amyloid fibril assembly

1996 ◽  
Vol 54 ◽  
pp. 752-753
Author(s):  
Beverly E. Maleeff ◽  
Timothy K. Hart ◽  
Stephen J. Wood ◽  
Ronald Wetzel
Keyword(s):  
Amyloid Fibril ◽  
Peptide Fragment ◽  
Hydrophobic Peptides ◽  
Amyloid Fibril Formation ◽  
Effects Of Ph ◽  
Severity Of The Disease ◽  
Kinetics Of ◽  
The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

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