Motor polarization dominance and "animal hypnosis"

Two kinds of dominanta were simultaneously formed under conditions of chronic experiments in rabbits. The motor polarization dominanta was formed under exposure of the right sensorimotor cortex of an animal to direct anodic current, and the state of "animal hypnosis" (the second dominanta) was induced. Animal behavior and electrophysiological characteristics were recorded. It was shown that the "animal hypnosis" induced at the optimum of the right motor polarization dominanta inhibited the motor reaction of the "dominant" extremity to testing stimuli. After the "animal hypnosis session, exposure of the right sensorimotor cortex to anodic current produced the latent excitation focus, which did not reach the level of summation. Two days later, exposure to testing stimuli developed the latent foci at first in the right cortex and then in subcortical structures. In the course of recovery of the motor polarization dominanta and its further change for the state characteristic of the "animal hypnosis", the patterns of cortical EEG coherence in the delta range typical of each kind of dominanta alternated in parallel with the time course of state changes.     

The motor dominant in man]

Study of the motor dominant in man has shown that in aftereffect of rhythmic electrocutaneous stimulation of hand, a latent focus of excitation is formed in the CNS. When using sensory stimuli (light, sound) and also stimuli, addressed to the second signal system, a hand motor reaction appears in the rhythm of earlier electrocutaneous stimulation, what testifies to preservation of rhythmic nature of excitation in the dominant focus. Summation process in the dominant focus is not reflected in human consciousness. Study of the brain biopotentials has shown that at formation of human motor dominant, typical changes of spectral-coherent characteristics of the neocortex electrical activity appear: within the "dominant" hemisphere, the spectrum power, increases in the range of low frequencies; highly coherent connections of electrical processes appear in the delta-range of the frontal-parietal area at conjugate decrease of combination of processes in the parietal-occipital area of the cerebral cortex. Formation of the dominant focus in one hemisphere causes general reconstruction of the structure of intercentral relations of both hemispheres electrical activity.     

Temperature reactions of the cerebral cortex in the rat and the distant effect of an experimentally evoked excitatory focus

By means of dynamic thermovision method, distant reactions of the cerebral cortex were studied in white rats appearing under local chemical action (2% KCl). Besides the previously described temperature wave SD (T-wave), in these conditions in the contralateral hemisphere local areas of warming up (0.2-0.3 degrees) were observed symmetrical with the place of stimulation. Under local chemical action, latent foci of excitation were revealed on dynamic thermal maps of the brain surface in the areas of the same or contralateral hemisphere, distant from the places of stimulation. During creation of two K+ foci a change was observed of place of T-wave appearance and of the usual order of its propagation over the cortex and also the formation of a focus of prolonged temperature fluctuations in the place of two T-waves meeting. On the basis of the obtained data a number of questions is discussed on the forms and mechanisms of distant effects in the CNS.     

Interaction between two excitation foci in the central nervous system capable for summation

The interaction between two dominant foci was carried out on different models of dominant. It was shown that the following pairs: latent motor and blinking excitation foci; hunger and hypnotic dominants, decaying polarization dominant (related with functioning of the left-hemisphere) and hypnotic dominant can function simultaneously. After repeated formation of a new dominant focus against the background of the existing stable dominant created earlier, a replacement of dominants takes place. This process passes through the stage of formation of the latent dominant not yet apparent at the behavioral level but with the electrical activity typical for the dominant focus. Actually, two dominants exist at this stage: the previous active and latent foci. The latter determines further behavior of the animal.     

Patterns of emotional and motivational interrelationships of irradiated male cats

After gamma irradiation within a wide range of doses (from 5 to 100 Gy) it was found that behavioural response of an emotional type (an evoked "pleasure" test) was more labile than the reaction based on a pronounced congenital hunter motivation (a "predator-victim" test). Exposure (50 Gy) of abdomen, when CNS was unaffected while a pronounced vegetative syndrome of the primary reaction developed within the first two hours, resulted in a more significant decrease in either behavioural pattern than it was observed after irradiation of the head.     

Antibody-mediated CNS demyelination: focal spinal cord lesions induced by implantation of an IgM anti-galactocerebroside-secreting hybridoma

O1 hybridoma cells, which secrete an IgM antigalactocerebroside, were implanted into the spinal cord of cyclosporine-treated juvenile or adult rats, and the animals were sacrificed ～2–3 wk later. About half the recipient animals developed myelin lesions. In some, sharply circumscribed foci of demyelination formed within the dorsal columns. Cellular reaction consisted of macrophages containing refractile globules in the parenchyma and within enlarged perivascular spaces as well as thickened endothelial cells. “Shadow plaques” also developed, i.e. regions in which axons were surrounded by thin myelin sheaths, compatible with remyelination. In addition, we found damaged axons, some of which were swollen with organelles, comparable to the enlarged axon profiles seen at sites of constriction or interruption. Compromise of the blood-brain barrier at sites of hybridoma growth was demonstrated by extravasation of Evans blue dye. Discontinuation of cyclosporine was followed by an anti-hybridoma, complement-fixing antibody response within 2–3 d. This model of focal CNS demyelination and remyelination, with evidence of some axon damage, is mediated by a defined IgM antiglycolipid monoclonal antibody secreted within the spinal cord parenchyma. The lesions, which are similar to those of multiple sclerosis, probably result from the interaction between the intrathecally secreted IgM antibody and complement entering from the circulation at foci of compromised blood-brain barrier plus activation of endogenous or hematogenous macrophages via their complement receptors.     

On the neuronal basis of figure-ground discrimination by relative motion in the visual system of the fly

A fly can discriminate an object (figure) from its background on the basis of motion information alone. This information processing task has been analysed, so far, mainly in behavioural studies but also in electrophysiological experiments (Reichardt et al., 1983). The present study represents a further attempt to bridge the gap between the behavioural and the neuronal level. It is based on behavioural and electrophysiological experiments as well as on computer simulations. The characteristic properties of figureground discrimination behaviour impose specific constraints on the spatial integration properties of the output cells of the underlying neuronal network, the heterolateral interactions in their input circuitry, as well as on the range of variability of their response. These constraints are derived partly from previous behavioural studies (Reichardt et al., 1983), partly, however, from behavioural response characteristics which have not been addressed explicitly so far. They are interpreted in terms of one of the alternative model circuits shown by Reichardt et al. (1983) to be sufficient to account for figure-ground discrimination. It will be demonstrated, however, that this can be done equally well by means of a further alternative model circuit. These constraints are used in the electrophysiological analysis for establishing visual interneurones as output elements of the neuronal network underlying figure-ground discrimination.In the behavioural experiments on figure-ground discrimination as well as on the optomotor course control the yaw torque generated by the tethered flying fly under visual stimulation was used as a measure for the strength and time course of the reaction. Therefore, it has initially been proposed that the three Horizontal Cells, which are regarded as the output elements of the neuronal network underlying the optomotor reaction (e.g. Hausen, 1981), might also control yaw torque generation in figure-ground discrimination (Reichardt et al., 1983). New behavioural data show, however, that the Horizontal Cells do not meet all the constraints imposed on the presumed output cells of the figure-ground discrimination network: (1) The Horizontal Cells are not sensitive enough to motion of small objects. (2) The heterolateral interactions within their input circuitry are not in accordance with the behavioural data (see also Reichardt et al., 1983). (3) The variability found in the time course of certain components of the yaw torque response to relative motion of figure and ground cannot be explained by their response characteristics. Hence, the Horizontal Cells cannot account for figure-ground discrimination on their own and additional output cells of the optic lobes with different functional properties are required to accomplish this task.     

Neuroinflammatory processes are important in neurodegenerative diseases: an hypothesis to explain the increased formation of reactive oxygen and nitrogen species as major factors involved in neurodegenerative disease development.

The hypothesis, as stated in the title, has arisen from the failure of simpler notions to explain a series of otherwise difficult to understand observations and the mounting evidence, in a broader sense, that inflammatory processes in the CNS are important etiologically in neurodegenerative diseases. Novel aspects include the primacy of inflammatory processes, within the CNS, which leads to increased formation of "proinflammatory" cytokines that lead to increased formation of reactive oxygen species (ROS) and mediation of the upregulation of genes that produce toxic products such as reactive nitrogen species (RNS). Here I utilize important background reports and synthesize ideas to help account for the noted increases in ROS and RNS and their biological reaction products in neurodegenerative diseases. The uniqueness of the CNS inflammatory processes include minimal damping of amplification processes, such as proinflammatory cytokine-mediated cascades, combined with unique genetic defects, that act in combination with other risk factors to repeatedly "spark" the inflammatory cascades to account for some of the major differences in neurodegenerative diseases. This hypothesis can be experimentally examined by development of definitive methods to quantitate unique products that are formed by processes predicted to occur under neurodegenerative conditions.     

Neuron correlates of the action result acceptor in a functional biotechnical complex structure

This study presents data illustrating neurophysiological features of the efferent-afferent convergence on the cortex neurons. It was established that, during the process of combining stimulation of the pyramidal tract (PT) axons with electrical skin reinforcement, a significant amount of neurons under study changed parameters of the activity evoked by the PT-stimulation. The most clear reconstruction of the PT-responses was obtained in experiments with inclusion of neurons into biotechnical complex by means of the feed back: "neuron-computer-stimulating devices-animal", representing an analogue of the functional system. The role of afferent-efferent convergence of the CNS neurons is discussed in dynamic deployment of the action result acceptor in the functional system of natural behavioural act.     

New fluorophore-forming reactions for histochemical visualization of N-acetylated and tertiary indolamines using glyoxylic acid,aluminum-formaldehyde and trifluoroacetic acid anhydride as reagents

Summary N-acetylated and tertiary indolamines, some of which are possible neurotransmitter candidates in the CNS, cannot be visualized with the standard Falck-Hillarp histofluorescence method and very little is known about their cellular localization. The present investigation demonstrates that glyoxylic acid (GA), formaldehyde (FA) in combination with aluminum ions (the ALFA method) and trifluoroacetic acid anhydride (TFAA) are capable of forming fluorescent compounds from N-acetylated (e.g. melatonin and N-acetyl-5-hydroxytryptamine) and tertiary (e.g. bufotenin) indolamines in histochemical protein models. With GA and FA-aluminum more vigorous reaction conditions were required for demonstration of these compounds compared to those needed for optimal visualization of primary catecholand indolamines (prolonged reaction time and higher concentration of GA and FA and aluminum ions). The fluorophore formation from N-acetylated and tertiary indolamines, which represents a new reaction principle in amine fluorescence histochemistry, is proposed to proceed as follows. In the first step, the indole reacts in 2-position with the reagent. The intermediate formed is dehydrated in the second step, yielding a strongly fluorescent 2-methylene derivative, which either per se or as the corresponding autoxidized dimer constitutes the main fluorophore. TFAA and related anhydrides represent new and potent reagents for histochemical visualization of N-acetylated indolamines such as melatonin. In contrast to the GA and ALFA reactions the optimal formation of fluorphores with TFAA required only mild reaction conditions (2–10 min at 0–20° C). The main fluorophore formed from melatonin has been identified and the reaction with TFAA is proposed to proceed as follows. An unstable intermediate, the isoimidinium carboxylate, is formed in the first step and this compound is then cyclized to form the fluorophore, 6-methoxy-1-methyl-3,4-dihydro--carboline. The GA and ALFA methods are already widely used for visualization of catecholamine systems. The fluorescence microscopical and microspectrofluorometric analysis did not, however, veveal any specific structures containing N-acetylated or tertiary indolamines in the rat CNS. The TFAA reaction was highly specific for N-acetylated indolamines when applied to protein models. However, in tissue a disturbing background fluorescence appeared, which under all reaction conditions tested, developed concomitantly with the specific fluorescence from melatonin. The problem with this background reaction has to be solved before the TFAA reaction can be applied for demonstration of N-acetylated indolamines in tissue.     

Surface photochemistry: benzophenone as a probe for the study of silica and reversed-phase silica surfaces.

This work reports the use of benzophenone, a very well characterized probe, to study new hosts: two reversed-phase silicas. Laser-induced room temperature luminescence of argon purged solid powdered samples of benzophenone adsorbed onto the two different reversed-phase silicas, RP-18 and RP-8, revealed the existence of a low energy emission band in contrast with the benzophenone adsorbed on 60 A pore silica, where only triplet benzophenone emits. This low energy emission band was identified as the fluorescence of the ketyl radical of benzophenone, which is formed as the result of a hydrogen atom abstraction reaction of the triplet excited benzophenone from the alkyl groups of the surface of the reversed silicas. Such emission does not exist for benzophenone adsorbed onto 60 A pore silica. Room temperature phosphorescence was obtained in argon purged samples for all the surfaces under use. The decay times of the benzophenone emission vary greatly with the alkylation of the silica surface when compared with "normal" silica surface. A lifetime distributions analysis has shown that the shortest lifetimes for the benzophenone emission exist in the former case. Triplet-triplet absorption of benzophenone was detected in all cases and is the predominant absorption in the case of 60 A pore silica, while benzophenone ketyl radical formation occurs in the case of the reversed silicas. Diffuse reflectance laser flash photolysis and gas chromatography-mass spectrometry techniques provided complementary information, the former about transient species and the latter regarding the final products formed after laser irradiation, both at 266 nm or 355 nm. Product analysis and identification show that the degradation photoproducts are dependent on the excitation wavelength, the photochemistry being much more rich and complex in the 266 nm excitation case, where an alpha-cleavage reaction occurs. A detailed mechanistic analysis is proposed.     

THE NATURE OF THE LATENT PERIOD IN THE PHOTIC RESPONSE OF MYA ARENARIA

The latent period in the response of Mya to illumination varies inversely as the duration of the exposure to which it is subjected. The reciprocal of the latent period, measuring the velocity of the process which underlies it, is a linear function of the exposure period. Since the duration of the exposure represents the amount of photochemical activity, it is concluded that the substances formed at that time act to catalyze a chemical reaction which determines the duration of the latent period. This explanation is in accord with the previous work on the photochemical reaction and with the effect of temperature on the latent period. As a result of the combined investigations there is presented a concrete hypothesis for the mechanism of photic reception in Mya.     

非充分灌溉及其生理基础

介绍了非充分灌溉的概念及内涵,主要阐述了在非充分灌溉条件下,作物体内产生的适应性生理反应,经非充分灌溉及轻度干旱处理,作物气孔阻力增加,蒸腾失水减少,作物水分散失对气孔开度的依赖性大于光合对其的依赖性。可通过气孔调节作物光合与水分的关系,最终提高作物的水分利用效率;有限度的水分亏缺,有利于同化物向籽粒调运,利用^14CO2标记研究表明,生长后期水分亏缺下,小麦体内存在对花前营养器官“临时库”同化物的再动员和对产量的补偿机制;适度水分亏缺促进了小麦等作物初生根的生长发育,增加深层土壤中的根系与根系活性,防止后期根系早衰。总之,在非充分灌溉条件下,作物能够在营养生长,物质运输和产量形成等方面产生有效的补偿机制,可作为非充分灌溉的重要理论基础。     

Neuro-pathophysiologic effects during primary hyperactivation of the bed nucleus of the stria terminalis in the rat brain

Penicillin administration into the bed nucleus of stria terminalis (BNST) in the rat brain caused epileptiform activity (EpA)--the formation of the generator of pathologically enhanced excitation (GPEE) in the nucleus. GPEE was registered during the first 3 days. EpA was also detected in the amygdala during 5-8 days, and in the hippocamp during the whole period of registration (2-3 weeks). There was the generalized enhancement of synchronized EpA in the range of 6-10 oscillations per s., in some cases with high-amplitude spindle (7-8 oscillations per s.). 50% of animals had emotional behavioural disorders, a marked fear reaction was observed for a month and more. Some animals demonstrated psychotic-like paroxysms with the elements of stereotypy accompanied by high-frequency low-amplitude EpA. It is suggested that when a primary GPEE in BNST is formed, the structures of septo-hippocampal system (BNST, amygdala, hippocamp) play a role of pathological determinants under the influence of which the pathological system consisting of a number of limbic and extrapyramidal structures is formed. Its activity is clinically manifested in the complex polymorphic neuropathological syndrome.     

Positive potentials ot the human brain in the latent presaccadic period under conditions of stimulation of the leading and nonleading eye

We used backward averaging method to study fast positive presaccadic EEG-potentials under conditions of the monocular stimulation of the leading and nonleading eye. Two schemes of the visual stimulus presentation ("no gap" and "overlap") were used. In the "no gap" condition, potential P1 dominated in the hemispere ipsilateral to a saccade direction. In the "overlap" condition, when the gaze was fixed at the central point, foci of this potential were localized in the sagittal derivations or in the same sites as in the "no gap" conditions. Irrespective on the stimulation scheme, the P2 foci were localized in the hemisphere contralateral to a saccade direction. We assume that the fast positive potentials involve both activation and inhibition processes in visuomotor structures and can be also associated with cognitive presaccadic processes (such as fixation disengage, attention lateralization and a preliminary extraction of motor programs from memory).     

Morphofunctional changes in the thymus of semisyngenous chimeras during the "graft versus host" response]

Activation of the enzymatic processes in the thymus cells was noted in the thymus gland at the early stages of the "transplantat-versus-host" reaction; the later stages were attended by inhibition of metabolic processes and reduction in number of immature and mature thymocytes in the cortical substance of the thymus. Besides, the cortical substance displayed accumulation of mesenchymal macrophages rich in lysosomal enzymes, particularly in the subcapsular layer where small foci of destruction formed at the late stages of the reaction.     

Possible involvement of the lipid-peroxidation product 4-hydroxynonenal in the formation of fluorescent chromolipids.

The effects of the lipid-peroxidation product 4-hydroxynonenal on the formation of fluorescent chromolipids from microsomes, mitochondria and phospholipids were studied. Incubation of freshly prepared rat liver microsomes or mitochondria with 4-hydroxynonenal results in a slow formation of a fluorophore with an excitation maximum at 360 nm and an emission maximum at 430 nm. The rate and extent of the development of the 430 nm fluorescence can be significantly enhanced by ADP-iron (Fe3+). With microsomes, yet not with mitochondria. NADPH has a catalytic effect similar to that of ADP-iron. Fluorescent chromolipids with maximum excitation and emission at 360/430 nm are also formed during the NADPH-linked ADP-iron-stimulated lipid peroxidation. Phosphatidylethanolamine and phosphatidylserine react with 4-hydroxynonenal revealing a fluorophore with the same spectral characteristics as that obtained in the microsomal and mitochondrial system. The findings suggest that the fluorescent chromolipids formed by lipid peroxidation are not derived from malonaldehyde, but are formed from 4-hydroxynonenal or similar reactive aldehydes via a NADPH and/or ADP-iron-catalysed reaction with phosphatidylethanolamine and phosphatidylserine contained in the membrane.     

NG2-glia as multipotent neural stem cells: fact or fantasy?

Cycling glial precursors-"NG2-glia"-are abundant in the developing and mature central nervous system (CNS). During development, they generate oligodendrocytes. In culture, they can revert to a multipotent state, suggesting that they might have latent stem cell potential that could be harnessed to treat neurodegenerative disease. This hope has been subdued recently by a series of fate-mapping studies that cast NG2-glia as dedicated oligodendrocyte precursors in the healthy adult CNS-though rare, neuron production in the piriform cortex remains a possibility. Following CNS damage, the repertoire of NG2-glia expands to include Schwann cells and possibly astrocytes-but so far not neurons. This reaffirms the central role of NG2-glia in myelin repair. The realization that oligodendrocyte generation continues throughout normal adulthood has seeded the idea that myelin genesis might also be involved in neural plasticity. We review these developments, highlighting areas of current interest, contention, and speculation.     

Prior exposure to methylenedioxyamphetamine (MDA) induces serotonergic loss and changes in spontaneous exploratory and amphetamine-induced behaviors in rats

The substituted amphetamine 3,4 methylenedioxyamphetamine (MDA) is a popular recreational drug of abuse. Administration of MDA to experimental animals has been shown to induce damage to serotonergic axons and nerve terminals. However, there is a lack of information on whether these treatments can produce any long-term changes in behavioural performance particularly under stressful conditions. In the present study, MDA (7.5 mg/kg; i.p.) was administered twice daily to adult male Sprague Dawley rats for four days. Four weeks following the last dose, spontaneous behaviors of these animals were tracked and scored in a novel "open field" environment using an automated video registration and computer interpretation system. Changes in behavior were observed in MDA treated animals including reductions in exploratory oriented behaviors (locomotion and rearing) and increases in grooming behavior when compared to vehicle treated controls. MDA-treated animals also displayed an enhanced locomotor and stereotyped response to d-amphetamine (12 mg/kg; i.p.). Significant reductions in 5-HT concentrations (20-30%) were observed in the frontal cortex, amygdala, striatum, and hypothalamus as a result of MDA treatment. In addition, [3H] paroxetine binding was reduced by (40%) in the cortex of MDA treated rats indicating that the decrease in 5-HT concentrations were accompanied by a reduction in intact presynaptic 5-HT nerve terminals. Changes in behavioural performance in a novel "open field" environment and following d-amphetamine challenge might be considered as a behavioural model of serotonergic deficit induced by MDA. The findings of this study also suggest that MDA use may increase both the abuse potential, and the propensity to develop psychosis as a result of abusing other psychostimulants such as d-amphetamine.