Changes in the oxygen tension level in different brain structures of rats in the waking-sleep cycle

Changes of oxygen tension level (pO2) in the visual cortex, dorsal hippocampus, lateral hypothalamus and central grey substance were studied during wake-sleep cycle in rats. The dependence was established of pO2 level changes on the character of behavioural reactions and on the accompanying hippocampal EEG activity: during orienting-investigatory and active defensive behaviour and also during paradoxical sleep, accompanied by hippocampal theta rhythm, pO2 level increased; during passive-defensive behaviour "freezing" reaction accompanied by desynchronization of the hippocampal rhythmic, the level of pO2 decreased. The obtained data confirm Routtenberg hypothesis about two relatively independent systems of ascending activation with different types of hippocampal EEG activity and supplement it with a thesis that the activity of these systems is accompanied by different shifts of brain oxidative metabolism.     

大鼠不同状态脑内神经递质功率的变化

目的:分析大鼠不同状态脑内递质功率的变化。方法:本研究采用脑涨落图仪。结果:与清醒状态相比,麻醉状态脑内递质的功率显著下降(P<0.05);大鼠死亡后脑内(死亡当时-死亡后48小时)6种递质的功率都降低到10-5级别(P值均大于0.05),说明死亡后不同时间脑内6种递质的功率无显著性差异。结论:从清醒状态到麻醉状态再到死亡状态,大脑的抑制程度逐渐加深。     

Distribution of oxygen tension in the brain of spontaneously hypertensive rats

The distribution of cerebral tissue pO2 in spontaneously hypertensive Okamoto-Aoki rats (SHR) and normotensive Wistar-Kyoto rats (WK) was studied by means of polarographic microelectrodes 1-3 microns in diameter. SHR exhibited pO2 shifts towards low values and an increased heterogeneity of pO2 distribution in the cerebral tissue. Morphological studies of the brain have revealed diffuse and focal ischemia in the grey and white matter of the brain in SHR.     

Effect of positive and negative emotional states on the electrical activity of the auditory cortex in rabbit ontogeny

It has been shown that in all age groups of animals, self-stimulation of the hypothalamus is accompanied with the decrease in the latent period and the increase in the amplitude of the evoked potential (EP) in the auditory cortex. During negative stimulation, the increase in temporal parameters of the response takes place together with the decrease in the amplitude of the EP and the onset of secondary waves. Significant age changes were revealed in the recovery of the initial pattern of the EP after cessation of stimulation of emotiogenic zones. The recovery of the EP after stimulation of the "reward" zone in younger rabbits occurs 4 times faster than in adult animals, whereas in the former the recovery period of the EP after stimulation of the "punishment" zone is significantly longer.     

Interhemispheric asymmetry of positive emotional reactions in rats

Interhemispheric asymmetry of positive emotional reactions was studied in rats: satisfaction of drinking need and self-stimulation. Successive inactivation of the hemispheres was carried out by potassium spreading depression. Switching off of the right as well as the left hemispheres symmetrically influenced the whole quantity of the water, drunk by the rats to a full thirst satisfaction, i. e. the magnitude of need. However, at different stages of drinking need satisfaction an interhemispheric asymmetry was observed: under a strong drinking motivation the right hemisphere dominated, under a weak motivation--the left one. Switching off of the right hemisphere lowered the frequency of self-stimulation of the lateral hypothalamus and switching off the left one heightened it, testifying to the dominance of the right hemisphere in the reaction of self-stimulation. This reaction was also characterized by asymmetry of the lateral hypothalamus nuclei; reactivity to hemispheres inactivation (decreasing or increasing of self-stimulation frequency) of the right nucleus was more expressed than that of the left one.     

Dynamics of oxygen tension in the brain and subcutaneous adipose tissue of newborn rats during anoxia and reoxygenation

The oxygen tension (pO2) in the brain and subcutaneous tissue of newborn rats was studied during anoxia and reoxygenation with hyperoxic gas mixtures. The level of pO2 in both tissues during anoxia fell from 10-30 mm Hg to 0 mm Hg. When newborn rats were reoxygenated with 50% or 100% O2, the oxygen tension in the brain and subcutaneous first increased and then decreased in spite of the hyperoxic inhalation. The decrease of pO2 in the subcutaneous during hyperoxia was more pronounced than that in the brain. Data obtained are discussed.     

Cross-cultural patterns in dynamic ratings of positive and negative natural emotional behaviour

Background

Studies of cross-cultural variations in the perception of emotion have typically compared rates of recognition of static posed stimulus photographs. That research has provided evidence for universality in the recognition of a range of emotions but also for some systematic cross-cultural variation in the interpretation of emotional expression. However, questions remain about how widely such findings can be generalised to real life emotional situations. The present study provides the first evidence that the previously reported interplay between universal and cultural influences extends to ratings of natural, dynamic emotional stimuli.

Methodology/Principal Findings

Participants from Northern Ireland, Serbia, Guatemala and Peru used a computer based tool to continuously rate the strength of positive and negative emotion being displayed in twelve short video sequences by people from the United Kingdom engaged in emotional conversations. Generalized additive mixed models were developed to assess the differences in perception of emotion between countries and sexes. Our results indicate that the temporal pattern of ratings is similar across cultures for a range of emotions and social contexts. However, there are systematic differences in intensity ratings between the countries, with participants from Northern Ireland making the most extreme ratings in the majority of the clips.

Conclusions/Significance

The results indicate that there is strong agreement across cultures in the valence and patterns of ratings of natural emotional situations but that participants from different cultures show systematic variation in the intensity with which they rate emotion. Results are discussed in terms of both ‘in-group advantage’ and ‘display rules’ approaches. This study indicates that examples of natural spontaneous emotional behaviour can be used to study cross-cultural variations in the perception of emotion.     

Changes in oxygen tension in the cerebral cortex during hemodilution

Wistar rats were subjected to gradual blood replacement with 7% albumin (hemodilution). Hematocrit and mean arterial pressure were measured periodically. Polarographic platinum microelectrodes with a tip 3-8 microns in diameter were used to study variation of oxygen tension (pO2) in the brain cortex during hemodilution. Some areas showed a significant decrease in the brain pO2 after hematocrit dropped to 30%. In animals with an initially low pO2 (13.1 +/- 1.7 mm Hg), this parameter decreased more slowly than in rats with a higher basic pO2 (24.5 +/- 1.7 mm Hg).     

Changes in the catecholamine content of brain structures in rats subjected to immobilization stress

The changes in DOPA and catecholamine (adrenaline, noradrenaline, dopamine) levels were investigated in noradrenaline- and dopamine-synthesizing brain nuclei of Wistar rats after prolonged immobilization stress on catecholamine analyzer (BAS, USA) using HPLC technique. Distinct DOPA and catecholamine changes were observed in locus ceruleus + nucleus subceruleus (1. c + n. sc) and substantia nigra at any stage after immobilization (right after immobilization and 15 and 30 days later). The most prominent alterations in noradrenaline content were detected in 1. c + n. sc. 30 days after immobilization NA level in these nuclei was 1.5 times higher, as compared to the control one. It is suggested that the increasing noradrenaline level in 1. c + n. sc. plays a defensive role in survival of rats after immobilization stress.     

Biochemical quantification of total brain glycogen concentration in rats under different glycemic states

All (13)C NMR studies of brain glycogen to date relied on observing the incorporation of (13)C label into glycogen, and thus interpretation was potentially affected by changes in (13)C label turnover rates. The goal of this study was to quantify total brain glycogen concentration under conditions of hypoglycemia or normoglycemia using biochemical methods. Rats were sacrificed using a focused microwave fixation device. The results showed that metabolism of brain glycogen was Glc- and insulin-sensitive and that insulin-induced hypoglycemia promoted a gradual glycogenolysis. Moreover, we show that there are very mild effects of isoflurane and alpha-chloralose anesthesia on brain glycogen concentration. Altogether these results show that total brain glycogen serves as a substantial source of glucosyl units during insulin-induced moderate hypoglycemia and therefore may be neuroprotective. Finally we also conclude that previous interpretation of (13)C NMR spectroscopy data accurately reflected the changes in total brain glycogen content.     

Electric reactive potentials to events of a positive and negative emotional nature

The event-related potentials (ERP) in the frontal and posterior associative cortex in the right and left hemispheres were studied in two different outcomes of tennis television game. These outcomes were "win" and "loss" of the ball, the first serving as a model of positive, the second--of negative emotional reactions. The averaging procedure was synchronized with the moment of ball crossing the racket line. The ERP consisted of four waves: P300, N600, P800, N1000. The most characteristic interhemispheric difference for the win was an increase of N600 wave in the left posterior associative cortex and for the loss--a decrease of P800 wave in the right frontal area. Thus the positive and negative emotional reactions have specific spatiotemporal organization and are based on complicated interaction of cortical areas.     

Sustained negative BOLD,blood flow and oxygen consumption response and its coupling to the positive response in the human brain

Most fMRI studies are based on the detection of a positive BOLD response (PBR). Here, we demonstrate and characterize a robust sustained negative BOLD response (NBR) in the human occipital cortex, triggered by stimulating part of the visual field. The NBR was spatially adjacent to but segregated from the PBR. It depended on the stimulus and thus on the pattern of neuronal activity. The time courses of the NBR and PBR were similar, and their amplitudes covaried both with increasing stimulus duration and increasing stimulus contrast. The NBR was associated with reductions in blood flow and with decreases in oxygen consumption. Our findings support the contribution to the NBR of (1) a significant component of reduction in neuronal activity and (2) possibly a component of hemodynamic changes independent of the local changes in neuronal activity.     

Resistance factor in emotional stress in the brain of rats

The authors review the results of extraction from the brain of emotional stress-resistant donor rats of fractions containing "factor" that causes the increased resistance to stress in recipient rats predisposed to stress. Brain homogenates of donor rats were subjected to thermal treatment, gel filtration on Sephadex G-15 and lyophilization. The fractions extracted are low-molecular weight, thermostable, resistant to pronase hydrolysis and significantly (P less than 0.05) increase the resistance of recipient rats to stress.