Application of a flexible polymer microECoG array to map functional coherence in schizophrenia model.

Anatomically, connections form the fundamental brain network, functionally the different types of oscillatory electric activities are creating a temporarily connected fraction of the anatomical connectome generating an output to the motor system. Schizophrenia can be considered as a connectome disease, in which the sensory input generates a schizophrenia specific temporary connectome and the signal processing becomes diseased showing hallucinations and adverse behavioral reactions. In this work, flexible, 32-channel polymer microelectrode arrays fabricated by the authors are used to map the functional coherence on large cortical areas during physiological activities in a schizophrenia model in rats.-Fabrication of a flexible microECoG array is shown.-Protocol to use a flexible microECoG is demonstrated to characterize connectome diseases in rats.-Customized method to analyze the functional coherence between different cortical areas during visually evoked potential is detailed.-R-based implementation of the analysis method is presented.

Electrophysiological and behavioral properties of 4-aminopyridine-induced epileptic activity in mice.

4-aminopyridine (4-AP) is a widely used drug that induces seizure activity in rodents, especially in rats, although there is no consensus in the literature on the dose to be used in mice. The aim of the present study was to investigate the effect of the intraperitoneal administration of 4-AP in two doses (4 and 10 mg/kg) in vivo. EEG, movement, and video recordings were made simultaneously in male B6 mice to specify the details of the seizures and to determine whether there is a suitable non-lethal dose for seizure induction and for further molecular studies. Seizure behavior in mice differs from that seen in rats, with no characteristic stages of epileptic seizures, but with spiking and seizure activity. Seizure activity, although produced at both doses without being lethal, induced different changes of the EEG pattern. Smaller dose induced a lower amplitude seizure activity, decreased spiking activity and later onset of seizures, while higher dose induced a much more intense brain seizure activity and severe trembling. It is concluded that the intraperitoneal administration of 4-AP at a dose of 10 mg/kg induces explicit seizure activity in mice which is repeatable and can be suitable for further molecular research.

Laminar analysis of initiation and spread of epileptiform discharges in three in vitro models.

Overexcitation of neuronal networks in some forebrain structures and pathological synchronization of neuronal activity play crucial role in epileptic seizures. Seizure activity can be elicited experimentally by different convulsants. Because of various distribution of excitatory and inhibitory connections in the neocortex there might be laminar differences in seizure sensitivity. Current source density (CSD) analysis or immunocytochemical c-Fos localization offer suitable tools to localize increased activation of neurons during seizure. In the present experiments, interictal epileptiform activity elicited by 4-aminopiridine, bicuculline or Mg(2+)-free solution was recorded with a 16-channel multielectrode assembly in different layers of the somatosensory cortex, and CSDs were calculated. Parallel c-Fos immunocytochemistry was applied. Each convulsant elicited characteristic activation pattern. 4-aminopiridine induced relatively short discharges, which were associated with a huge sink in layer V, the sink and source pattern was relatively simple. Mg(2+)-free solution elicited the longest discharges, sinks appeared typically in the supragranular layers II and III than quickly distributed toward layers V and VI. Bicuculline induced rather similar seizure pattern as Mg(2+)-free solution, but the amplitudes of field potentials were larger, while the durations shorter. The peak of c-Fos activation, however, was not parallel with the largest electrical activation. Larger amount of stained cells appeared in layers II and III in 4-aminopiridine and bicuculline, respectively. In Mg(2+)-free solution the highest c-Fos activity was detected in upper layer VI. Long-lasting cellular effects do not always correspond to the largest electrical responses, which are primarily determined by the activation of asymmetrical pyramidal neurons. Interneurons, which possess more symmetric process arborisation, play less important role in the generation of field potentials, although they may be intensively activated during seizure.

Neutron imaging of Zr-1%Nb fuel cladding material containing hydrogen.

Hydrogen distribution and hydride phases were analyzed in reactor fuel cladding pressure tube Zr-1%Nb material up to 13,300 ppm. From neutron diffraction measurements, formation of cubic delta-ZrH2 and a small amount of tetragonal gamma-ZrH was established. Texture effects were analyzed by imaging plate technique. From neutron radiography images a linear model was set up that adequately described the relationship between gray levels and nominal H-concentrations. The H-distribution was unveiled by 3D intensity histograms and fractal analysis of multilevel-segmented neutron radiography images.

Developmental regulation of the inhibitory effect of dopamine on prolactin release in the preterm neonate.

The secretion and release of prolactin from the anterior pituitary is under the tonic inhibitory control of endogenous dopamine produced in the central nervous system. Exogenous dopamine inhibits prolactin secretion by reaching the pituitary via the portal circulation, and the hypolactotropic effect of dopamine infusion has been documented in all age groups in humans. However, the maturation of lactotroph sensitivity to dopaminergic inhibition has not been studied. Therefore, we followed the changes in serum prolactin concentrations before, during, and after dopamine infusion in 19 sick preterm infants with a mean gestational age of 30.6+/-0.6 weeks during the first 3 days of life, and examined the relationship of the hypolactotropic effect of dopamine to gestational age and birth weight in this patient population. As expected, dopamine therapy resulted in a decrease in mean serum prolactin from 89.4+/-9.5 to 58.6+/-9.1 microg/l (p < 0.05) with a return of the serum prolactin concentration to the pretreatment level 2-6 h after discontinuation of drug administration (98.3+/-11.7 microg/l, p < 0.05). However, simple regression analysis of the individual data revealed that the magnitude of the dopamine-induced decrease in serum prolactin was significantly influenced by gestational age (p = 0.006) and birthweight (p = 0.037). Thus, our findings provide evidence for the maturation of pituitary lactotroph sensitivity to dopaminergic inhibition in the preterm human neonate.

On the role of self-excitation in the development of topographic order in the visual system of the frog.

A two-level model is presented for explaining the development of the topographically ordered retinotectal connections of the visual system of the frog. The columnar structure of the tectum were taken into account explicitly. Simulations suggest that the self-excitatory intracolumnar connections play an important role in the formation of the topography. In the case of self-excitation the system is able to recognize the topology of the visual field by the continuity of the object's movement.

Prevention of pulmonary complications during neonatal resuscitation.

The pulmonary functions were measured during resuscitation of eight critically ill newborns by the "Pulmonary Evaluation and Diagnostic System" (PEDS UNIT-M.A.S. Inc.) The asphyxiated infants (Apgar score 0-3; PH 6, 9) required more aggressive ventilator support than "traditional" cases. The danger of the pulmonary injuries was larger in this period. In spite of this, there were no signs of air leaks syndrome and the oxygenation was improved in every case. Worsening or improving the pulmonary mechanics it is possible to change the ventilator settings immediately. This method seems to be advisable to introduce in the everyday routine to prevent iatrogenic pulmonary complications in such critical situation--the reanimation.

[Continuous respiratory therapy of newborn and premature infants with respiratory disorders]. / Légzészavarban szenvedö újszülöttek és koraszülöttek tartós respirációs kezelése.

2216 newborns and prematures with respiratory distress of different underlying diseases were treated with long term respiratory therapy from 1. Jan. 1975 to 31. Dec. 1985. One part of the patients were born in our hospital, the other part of them were transported from outside. The rate of prematures was 81.2%. The respiratory therapy was applied in 1813 cases because of pulmonary diseases (group 1.), while in 403 cases the respiratory troubles were extrapulmonary in origin (group 2.). The diseases in the first group were as follows: hyaline membrane disease in 482 cases (27.30%), intrauterine pneumonia in 634 cases (34.64%), postnatal pneumonia in 291 cases (15.90%), meconium aspiration syndrome in 110 cases (6.01%), severe RDS-II in 158 cases (8.63%), pulmonary immaturity in 116 cases (6.35%), persistent fetal circulation in 21 cases (1.15%) and pulmonary aplasia on the left in 1 case (0.021%). In the second group the greatest part of the cases were treated for neurological disturbances. We discuss the indications of different types of respiratory therapy and the complications as well. The survival rate was in the first group 59.3%, while in the second only 16.9%. Therefore the respiratory therapy seems to be more effective in the pulmonary diseases of the newborns. The mortality rate and the rate of severe complications were lower among inborn babies because of the early application of the respiratory therapy.