Hippocampal GABAergic interneurons coexpressing alpha7-nicotinic receptors and connexin-36 are able to improve neuronal viability under oxygen-glucose deprivation.

The hippocampal interneurons are very diverse by chemical profiles and rather inconsistent by sensitivity to CI. Some hippocampal GABAergic interneurons survive certain time after ischemia while ischemia-sensitive interneurons and pyramidal neurons are damaged. GABAergic signaling, nicotinic receptors expressing α7-subunit (α7nAChRs(+)) and connexin-36 (Cx36(+), electrotonic gapjunctions protein) contradictory modulate post-ischemic environment. We hypothesized that hippocampal ischemia-resistant GABAergic interneurons coexpressing glutamate decarboxylase-67 isoform (GAD67(+)), α7nAChRs(+), Cx36(+) are able to enhance neuronal viability. To check this hypothesis the histochemical and electrophysiological investigations have been performed using rat hippocampal organotypic culture in the condition of 30-min oxygen-glucose deprivation (OGD). Post-OGD reoxygenation (4h) revealed in CA1 pyramidal layer numerous damaged cells, decreased population spike amplitude and increased pair-pulse depression. In these conditions GAD67(+) interneurons displayed the OGD-resistance and significant increase of GABA synthesis/metabolism (GAD67-immunofluorescence, mitochondrial activity). The α7nAChRs(+) and Cx36(+) co-localizations were revealed in resistant GAD67(+) interneurons. Under OGD: GABAA-receptors (GABAARs) blockade increased cell damage and exacerbated the pair-pulse depression in CA1 pyramidal layer; α7nAChRs and Cx36-channels separate blockades sufficiently decreased cell damage while interneuronal GAD67-immunofluorescence and mitochondrial activity were similar to the control. Thus, hippocampal GABAergic interneurons co-expressing α7nAChRs and Cx36 remained resistant certain time after OGD and were able to modulate CA1 neuron survival through GABAARs, α7nAChRs and Cx36-channels activity. The enhancements of the neuronal viability together with GABA synthesis/metabolism normalization suggest cooperative neuroprotective mechanism that could be used for increase in efficiency of therapeutic strategies against post-ischemic pathology.

Contribution of protease-activated receptor 1 in status epilepticus-induced epileptogenesis.

Clinical observations and studies on different animal models of acquired epilepsy consistently demonstrate that blood-brain barrier (BBB) leakage can be an important risk factor for developing recurrent seizures. However, the involved signaling pathways remain largely unclear. Given the important role of thrombin and its major receptor in the brain, protease-activated receptor 1 (PAR1), in the pathophysiology of neurological injury, we hypothesized that PAR1 may contribute to status epilepticus (SE)-induced epileptogenesis and that its inhibition shortly after SE will have neuroprotective and antiepileptogenic effects. Adult rats subjected to lithium-pilocarpine SE were administrated with SCH79797 (a PAR1 selective antagonist) after SE termination. Thrombin and PAR1 levels and neuronal cell survival were evaluated 48h following SE. The effect of PAR1 inhibition on animal survival, interictal spikes (IIS) and electrographic seizures during the first two weeks after SE and behavioral seizures during the chronic period was evaluated. SE resulted in a high mortality rate and incidence of IIS and seizures in the surviving animals. There was a marked increase in thrombin, decrease in PAR1 immunoreactivity and hippocampal cell loss in the SE-treated rats. Inhibition of PAR1 following SE resulted in a decrease in mortality and morbidity, increase in neuronal cell survival in the hippocampus and suppression of IIS, electrographic and behavioral seizures following SE. These data suggest that the PAR1 signaling pathway contributes to epileptogenesis following SE. Because breakdown of the BBB occurs frequently in brain injuries, PAR1 inhibition may have beneficial effects in a variety of acquired injuries leading to epilepsy.

Proteasomal activity in brain tissue following ischemic stroke in Wistar rats.

Functional as well as structural reorganization of brain tissues takes place in the surrounding and remotes brain areas after focal ischemic lesions. In particular, reactive or regenerative processes have been described to occur in the infarction areas and the contralateral hemisphere. Experiments were performed on 63 rats, divided into 3 groups (each consisted of 21 animals): sham operated, short-term occlusion of the right middle cerebral artery (MCAO) group, and long-term MCAO group. We have studied changes in proteasome proteolysis during transient occlusion of the middle cerebral artery using method of Koizumi J., duration 2 and 60 min and made the comparison between changes in different types of proteasome activity and severity of ischemic injury and showed three types of decrease inproteolytic activity (trypsin-, chymotrypsin-like, peptidylglutamyl peptide-hydrolyzing) in the brain tissues. Chymotrypsin-like activity of ischemic areas of the brain for short-term MCAO decreased 4.1 times compared with controls (P > 0.05), for long-term MCAO decreased 5.8 times compared with controls (P < 0.05). Trypsin-like activity of ischemic areas of brain for short-term MCAO decreased 7.1 times compared with controls (P > 0.05), for long-term MCAO decreased 12.5 times compared with controls (P < 0.05). PGPH activity of ischemic areas for short-term MCAO decreased 8 times compared with controls (P > 0.05), for long-term MCAO decreased 2.8 times compared with controls (P < 0.05). The similar dynamics was observed also in the penumbra and the core zone of the brain at 6 h of reperfusion, in the long run there is no significant difference between the core and contralateral zones. Our results suggest that proteasome activity may play also a role in contralateral cortical plasticity occurring after focal cerebral ischemia.

Hippocampus remodeling by chronic stress accompanied by GR, proteasome and caspase-3 overexpression.

Chronic stress is a threat to homeostasis for many brain regions. While hippocampal formation is one of the most stress-sensitive areas of the cortex, molecular changes occurring as a result of increased glucocorticoid neurotoxicity in hippocampus are largely unknown. The aim of these studies was to investigate mRNA expression of mineralocorticoid and glucocorticoid receptors (MR, GR), proteasome subunits ß5 (constitutive subunit) and ß1i (inducible immunoproteasome subunit), mTOR (mammalian target of rapamycin), bcl-2; as well as caspase-3 immunoreactivity (confocal microscopy) in adult Wistar rat hippocampus following 10-day restraint stress (plastic restrainers, 6h daily). Chronic restraint led to a significant reduction in number of neuronal and astroglial cells in hippocampal regions CA1-3. This reaction was combined with substantial increase in GR and decrease in MR mRNA levels with the greatest response - 1.5-fold amplitude increase - observed in dentate gyrus and CA3 correspondingly. Stress did not change the expression of constitutive ß5 subunit but dramatically enhanced expression of inducible ß1i subunit and increased mTOR, and bcl-2 mRNA expression. Multiple scattered cells demonstrating caspase-3(+) profile were found in hippocampus of stressed animals. The study demonstrates that hippocampal remodeling induced by chronic restraint stress is associated with GR, immunoproteasome, mTOR, caspase-3 and bcl-2 overexpression in hippocampus.

The neuroprotective effect of 2-oxoglutarate in the experimental ischemia of hippocampus.

In this study we investigated the potential neuroprotective effect of 2-oxoglutarate (2-OG) on the hippocampus in the transient vessel occlusion ischemia model in the Mongolian gerbil. The morphological and biochemical studies were performed at 7 days after occlusion of carotid arteries. The acute reduction of NeuN-positive neurons in the CA1 pyramidal layer of the hippocampus was accompanied by increased staining intensity for GFAP-positive astrocytes, indicative of glial reaction. The neuron death in the CA1 area coincided with a strong 2.4 fold decrease in the membrane forms of neuronal cell adhesion molecules and elevated levels of astrocyte-specific proteins (soluble GFAP to 2,6 times; filament GFAP to 1,5 times; calcium-binding protein S-100b to 1,6 times). Treatment with 2-oxoglutarate (2.28 g/l drinking water) for between 7 and 21 days attenuated the neuronal death and reactive astrogliosis in this model of experimental ischemia by 20-50%. Our results suggest that 2-OG may prevent the disturbances of neural cells that usually take place during ischemic pathology.

The effect of neuraminidase blocker on gabazine-induced seizures in rat hippocampus.

Concentration of neuraminidase (NEU), an enzyme which cleaves negatively charged sialic acids from carbohydrate moieties of the cellular membrane, could vary depending on physiological conditions. Multiple evidences suggest that fluctuations of NEU extracellular concentrations can influence neuronal activity. In the present study we examined the effect of down regulation of endogenous NEU activity on seizure-like activity (SLA) induced by gabazine (specific blocker of inhibitory synaptic transmission) in the hippocampal CA1 pyramidal region of cultured slices. We show that in slices pretreated with the blocker of endogenous NEU, N-acetyl-2,3-dehydro-2-deoxyneuraminic acid (NADNA), duration of synchronous oscillations induced by gabazine was considerably increased comparatively to control untreated slices. This study adds further information that changes in the level of NEU activity is an important factor, which can affect neuronal network excitability.

Remodeling of ammon's horn during the first two weeks of experimental diabetes development.

It is known that long-term diabetes mellitus causes hippocampal dysfunction, however, early events leading to diabetes-related impairments of hippocampal tissue remain obscure. The present study was performed to examine temporal and spatial patterns of neuronal damage and astrogliosis in hippocampal CA1-C3 areas during the early stage of streptozotocin-induced diabetes in rats. NeuN and GFAP immunohistochemistry was used to visualize neurons and glial cells. Immunopositive cells were counted in hippocampal CA1-CA3 areas at days 3, 7 and 14 of diabetes development using confocal Olympus FV1000 microscope. Significant decrease in the number of neurons in CA2 area was observed in diabetic rats at day 3. In contrast, in CA1 and CA3 areas NeuN-positive cell count started to decrease later being at day 7, correspondingly, by 7 and 9 % lower than that in the control. This trend developed further till day 14, when the number of neurons in CA1 and CA3 areas was, respectively, 20.3 and 18.1% smaller as compared with the control. These changes were accompanied by astrogliosis: the number of astrocytes in pyramidal cell layer was increased significantly in all examined time-points. Thus, our study demonstrates that streptozotocin-induced diabetes is associated with early neurodegeneration in Ammon's horn. It suggests that clinically relevant cognitive deficits development in diabetic patients starting from the early stage of the disease.

Morphological and functional changes in rat hippocampal slice cultures after short-term oxygen-glucose deprivation.

To study effects of short-term cerebral ischemia, hippocampal slice cultures were subjected to oxygen and glucose deprivation (OGD) followed by a period of normoxic reoxygenation. Propidium iodide staining, and MTT/formazan-assay were used to evaluate cell viability and metabolic activity. CA1 pyramidal cells were analyzed at the light- and electron microscopic levels. Cell damage was found to be insignificant during the first hour after 10 min OGD but profound following 4 h, showing delayed neuronal cell damage caused by short-term OGD. Our model can be used to characterize the mechanisms of cell damage caused by mild cerebral ischemia. These data might apply to further development of neuroprotective tools for the treatment of brain diseases.

Myelination and demyelination processes in the rat cerebellum cell culture: an electron microscopic study.

We observed manifestations of the myelination process in dissociated culture of the cerebellar tissue of newborn rats and modifications of the structure of myelin sheaths after treating the culture with a demyelinating factor, blood serum of patients suffering from multiple sclerosis (MS). On day in vitro (DIV) 26, in the control myelin sheaths of the axons demonstrated the closest resemblance to those observed in vivo, and we selected this term for inducing demyelination. Addition of the serum of MS patients to the culturing medium evoked rapid (in 3-6 hours) dramatic changes in the ultrastructure of myelin sheaths; these were a decrease in the number of the lamellae, their splitting and invagination, formation of vesicles, etc. The serum of MS patients in an acute stage of the disease exerted more intensive demyelination effects than that of patients in a remission stage.

The influence of Hericium erinaceus extract on myelination process in vitro.

Myelin sheaths, wrapping axons, perform the following important functions: support, protection, feeding and isolation. Injury of myelin compact structure leads to an impairment and severe illness of the nerve system. Exact mechanisms underlying the myelination process and myelin sheaths damage have not established yet. Therefore search for substances, which provide regulatory and protective effects on the normal myelination as well as stimulating action on the remyelination after myelin damage, is of special interest. Recently it was shown that extract from mushroom Hericium erinaceus had activating action on the nerve tissue. So the aim of the present work was to study an influence of an extract from H. erinaceus on the cerebellar cells and the process of myelination in vitro. Obtained data revealed the normal growth of the nerve and glial cells with extract at cultivating. No pathologic or toxic action of the extract has been found. The cell ultrastructure was intact and similar to that observed in vivo. The process of myelination in the presence of the extract began earlier as compared to controls and was characterised by a higher rate. Thus, extract of H. erinaceus promoted normal development of cultivated cerebellar cells and demonstrated a regulatory effect on the process of myelin genesis process in vitro.

Computer simulation approach to the quantification of immunogold labelling on plasma membrane of cultured neurons.

Cell culture is a convenient model system to study the expression of plasma membrane-bound proteins in nerve cells. Analysing it with an ultrastructural detail researchers often apply transmission electron microscopy together with immunogold labelling. Plasma membrane profiles are one-dimensional (1D) and provide little information about the topography of membrane-bound proteins. In order to convert 1D estimates of spatial arrangement for preembedding immunogold labelled proteins into two-dimensional (2D) quantities, namely the 2D pattern and density of labelling, this paper presents a simple computer simulation technique. This technique is based on a mathematical model permitting a simulated immunogold labelled membrane to be sampled in a way similar to microtome sectioning. An interlabel distance (ILD) estimate is used to define the position of immunogold particles in membrane profiles. In order to interpret experimental ILD measurements the simulated distribution best fit to the experimental data is selected and the corresponding 2D density and pattern of particle scattering are considered to explain the real situation. Various parameters including a cell section thickness, immunogold particle size etc can be adjusted to suit the demands of a particular experiment. The technique was applied to quantify the NCAM preembedding immunogold labelling in the plasma membrane of cultured rat hippocampal neurons.

Microglia in organotypic hippocampal slice culture and effects of hypoxia: ultrastructure and lipocortin-1 immunoreactivity.

Lipocortin-1 immunocytochemistry was used to study the various cell forms of microglia that appear during organotypic hippocampal tissue culture, as well as in the in vitro toxic hypoxia model. Antibodies against lipocortin-1 identified activated and phagocytic cells that were abundant in a slice after the plating of a culture: cells of the intermediate form at the later time-points of culturing, resting ramified microglia beginning from the seventh day of culturing, as well as activated and phagocytic cells that appeared in the slice after experimental toxic hypoxia induced by potassium cyanide treatment. Lipocortin-1-positive microglia cell forms corresponded well to the description of the microglia in vivo, and the morphology of microglia corresponded to the circumstances under which these cells were observed in slice cultures. Electron microscopic studies have demonstrated, for the first time, that microglia in organotypic slice culture preserve morphological features typical of different microglial forms in vivo, as well as specific contacts and interactions with the other neural tissue elements. After experimental toxic hypoxia, rapid changes in microglial ultrastructure and localization were observed, reminiscent of in vivo models of ischaemia. In conclusion, observations of microglial morphology and behaviour allow us to suggest that microglia in the organotypic culture preserve their essential characteristic features and properties, thus providing an important model system for studying the structure and function of these cells.

Microglia and astrocytes in the adult rat brain: comparative immunocytochemical analysis demonstrates the efficacy of lipocortin 1 immunoreactivity.

The distribution of glial cells (microglia and astrocytes) in different regions of normal adult rat brain was studied using immunohistochemical techniques and computer analysis. Lipocortin 1, phosphotyrosine, and lectin GSA B(4), were used for identification of microglia, while S100beta and glial fibrillary acidic protein identified astrocytes. Bioquant computerized image analysis was used to quantify and map the immunostained cells in sections from adult rat brain. If lipocortin 1 was used as a marker, more microglial cells were detected than with phosphotyrosine or lectin. The lipocortin 1-positive microglial population was most numerous (on average, 130+/-5 cells/mm(2) of the brain section area) in neostriatum, and least (51+/-4 cells/mm(2)) in cerebellum and medulla oblongata. In general, the density of lipocortin 1 microglia was higher in the forebrain, and lower in the midbrain, and the least in the brainstem and cerebellum. The number of S100beta astrocytes was two to three times larger than the number of microglial cells, and approximately two times greater than glial fibrillary acidic protein cells. A high density of astrocytes was found in the hypothalamus and hippocampus (more than 260 cells/mm(2)); they were more numerous in the white matter than in the gray matter. Fewer astrocytes were observed in the cerebral cortex, neostriatum, midbrain, medulla oblongata and cerebellum (less than 200 cells/mm(2)). Thus lipocortin 1 and S100beta were shown to be the most specific and reliable markers for microglia and astrocytes, respectively. The regional population differences demonstrated for lipocortin 1 microglia and S100beta astrocytes presumably reflect structural and functional specializations of the certain brain regions.

[Changes in the topography of various proteins in cultured neurons after selective injury of various cytoskeletal elements with neurotoxins]. / Izmeneniia topografii nekotorykh belkov vneshnei membrany kul'tiviruemykh neironov pri izbiratel'nom povrezhdenii razlichnykh élementov tsitoskeleta neirotoksinami.

The spinal cord and hippocampal primary cultures were incubated with three neurotoxins (separately) known to impair the main components of the cytoplasmic cytoskeleton: 1) colchicine blocking the repolymerization of microtubules, 2) cytochalasin preventing elongation of actin filaments, and 3) beta, beta'-iminodipropionitrile (IDPN), causing disorganisation of neurofilaments. The distribution of surface membrane molecules on the surface of the neurons was evaluated in the ultrastructural study after treatment with the neurotoxins on the 5th, 12th, and 15th days in vitro (DIV). On the 12 DIV, the density of immunogold labelled neural cell adhesion molecules (NCAM) on IDPN-treated hippocampal neurons increased 1.45 times comparing to the controls. On the 5 DIV, the density of WGA (wheat germ agglutinin)-binding membrane glycoproteins increased 2.09 times on colchicine-treated neurons, and 3.98 times on cytochalasin-treated ones, whereas on the 12 DIV, the increase was 3.28 and 2.72 times, respectively, as compared to the control cultures of the same age. These data provide insights into the mechanisms of neurodegenerative changes in the nerve cells and into the relationship between the cytoskeletal elements and the surface molecules on the neuronal plasmatic membrane.

Increased immunogold labelling of neural cell adhesion molecule isoforms in synaptic active zones of the chick striatum 5-6 hours after one-trial passive avoidance training.

An area of the chick striatum, the lobus parolfactorius plays an important role in one-trial passive avoidance learning tasks. In the present study we report evidence that 5-6 h post-training, a significantly higher proportion of synaptic active zones in this area contain labelled epitopes of the neural cell adhesion molecule, with the greatest occurrence of labels at the edges of active zone profiles (in both control and trained groups). This suggests that there is a period after training when expression of the neural cell adhesion molecule in synaptic membranes almost doubles, and that events at active zone edges may play a specific role in mechanisms of synaptic adhesion. Cellular mechanisms of long-term memory formation are believed to include alterations in neural circuitry at the synaptic level. The involvement of the neural cell adhesion molecule (NCAM) in functional synaptic modifications has been demonstrated using a number of physiological models. Performance of rats in the Morris water maze, a spatial learning paradigm which requires the hippocampus, is impaired by either intraventricular injection of NCAM antibodies, or injection into the hippocampus of an enzyme which increases homophilic adhesion of the molecule, due to the removal of polysialic acid residuals from extracellular NCAM domains. In addition, intraventricular injections of anti-NCAM antibodies 6-8 h post-training were shown to impair memory for a one-trial passive avoidance task in the rat. An avoidance training model in the one-day-old chick indicates a similar time window, 5-6 h post-training during which memory for the task can be impaired by intraventricular injection of NCAM antibodies. In the hyperstriatum ventrale, a chick forebrain area involved in the passive avoidance task. subtle changes in the distribution pattern, but not density of NCAM molecules in synaptic membranes were revealed 5-6 h post-training. However, on the basis of studies of synaptic morphometry, a region of striatum, the lobus parolfactorius (LPO), appears to play a more important role in longer term memory storage for the task.

Growth related changes in sugar determinants on the surface of C6 glioma cells in culture: a cytochemical lectin-binding study.

The cell surface sugar determinants (CSSD) were examined in C6 glioma cells in cultures at different conditions of growth by peroxidase conjugates of the lectins: peanut agglutinin (PNA), Ricinus communis agglutinin (RCA), Helix pomatia agglutinin (HPA), wheat germ agglutinin (WGA), lentil agglutinin (LCA), laburnum bork agglutinin (LABA), and lotus agglutinin (TPA). It was found that the cells bound more intensively WGA, LCA, and RCA compared to PNA, HPA; the weakest staining was provided by LABA and TPA. Binding intensity for PNA significantly increased after pretreatment of the cells with neuraminidase. This indicates that a part of the beta-D-galactose residues on the surface membrane of C6 glioma cells is covered by sialic acid. The process of sialization was increased during the culturing of C6 glioma cells. Addition of cis-DDP or dBcAMP to cultures growing in medium with 10% of CS increased the number of Gal residues which are not covered by sialic acid. The expression of beta-D-galactose (Gal), N-acetyl-D-galactosamine (NAcDGal), and fucose (Fuc) residues appeared to be most responsive to changes in growth conditions and degree of cell differentiation. The expressions of N-acetyl-D-glucosamine (NAcDGlc) and mannose (Man) residues were high and seems did not depend on changing of the conditions of culturing. In C6 glioma cells cultures in which the rate of cell division, formation of the cell processes, and adhesiveness of the cells to the substratum were reduced by growing cells in MEM+, expression of beta-Gal, NAcDGal, and Fuc was considerably reduced. The decrease of expression of beta-Gal, NAcDGal, and Fuc on the surface of cell membrane was more pronounced in MEM+ with 1% of CS than in MEM+ with 10% of CS. In DbcAMP and cis-DDP treated cultures, grown in medium with 1% serum, in which cell division was inhibited without obvious changes in cell adhesiveness to the substratum, binding of PNA and HPA was increased due to higher expression of beta-Gal and NAcDGal. From these observations it was concluded that the pattern of expression of sugar residues on the cell surface varies according to the biological state of the cells and are easily affected by tissue culture conditions.

Neural cell adhesion molecule (N-CAM) distribution may predict the effect of neurotoxins on the brain.

The neural cell adhesion molecule (N-CAM) is a convenient neurospecific marker for investigating the effects of neurotoxins on cell migration, cell recognition and differentiation of neurons during development. In this report, we discuss the developmental toxicity of valproic acid studied by two different approaches (the immunochemical detection of N-CAM content and polypeptide composition, and immunohistochemical analysis of N-CAM topography). Immunohistochemical analysis of distribution of N-CAM as a surface marker on the neural cells predicted the effect of the neurotoxin.

Lateral patterns of the neural cell adhesion molecule on the surface of hippocampal cells developing in vitro.

In monolayer cultures of hippocampal neurons from newborn rats, an immunocytochemical quantitative study was carried out to investigate age-dependent arrangement of the neural cell adhesion molecules in different parts of cell membranes. On the fifth and 12th day in vitro, neural cell adhesion molecules were labelled with specific antibodies and protein A conjugated to colloidal gold particles. Samples of randomly selected electron micrographs that displayed labelled membrane fragments of cell bodies, growth cones, and axons were numerically analysed for the five- and 12-day in vitro neurons. Neural cell adhesion molecules surface topography was quantitatively described and compared, using a statistical stereological approach. The mean surface density of labelled neural cell adhesion molecules was found to be approximately 2.5 times higher in growth cone membranes relative to somatic and axonal membranes in five-day in vitro neurons. By the 12th day in vitro, this density decreases in somatic membranes (approximately 18%) and increases in axonal membranes (approximately 60%). Representative spectra of lateral intervals between labels as well as images that show typical topography of label on membrane surfaces were simulated. The results revealed regular patterns of neural cell adhesion molecules on the somatic surface and allowed consideration of neural cell adhesion molecules arrangement in a view of membrane adhesion properties. Participation of cytoskeleton in neural cell adhesion molecules rearrangement is discussed.

Changes in the neural cell adhesion molecule patterns on the rat glial cell surfaces with development and contact formation in vitro.

In monolayer cultures of newborn rat hippocampal cells, immunogold-labelling at the electron microscope level was used to study quantitatively the neural cell adhesion molecule (N-CAM) arrangement on the surface of glial soma and processes on 5 and 12 days in vitro (DIV). Four corresponding samples of micrographs were formed. To quantify the labelling, a stochastic geometry approach was used. Spectra of lateral distances between labels as well as simulated images of the surface label arrangement (invisible in micrographs) were derived and compared. The data show that, on both 5 and 12 DIV, N-CAM density on the surface of processes is approximately 2 times higher than that in somata; 12-DIV cells showing a lower (approximately 25%) N-CAM surface density as compared with the 5-DIV cells. This suggests that N-CAM expression in glia surfaces decreases while the cells form contacts, and N-CAM sorting between soma and processes remains stable. The simulated topographies of the lateral N-CAM arrangement might highlight fundamental mechanisms that underlie formation of the neural network.