Ontogenetic development of electrocorticogram in the rat

Spontaneous electrocorticogram (ECoG) was recorded in frontal (sensorimotor) temporal (auditory) and occipital (visual) cortical regions of 86 male rats (immobilized with d-tubocurarine) aged from 3 days to adulthood. Activity which could be classified as ECoG was for the first time recorded in 5-day-old rats; it was formed by groups of slow waves with unstable frequency intermingled with periods of isoelectric line. Discontinuous ECoG activity was regularly registered even in 10-day-old rats, exceptionally in 12-day-old rats. During further maturation of the continuous ECoG an increase in frequency and an establishment of a basic rhythmic activity synchronous over both hemispheres took place, so that 25- and 30-day-old rats did not differ from the adult ones. Autocorrelagrams and power frequency spectra demonstrated a broad frequency range of the basic rhythm as well as delay in the development of occipital cortical areas in comparison to frontal areas.     

Biological rhythms of tissue basophils of the dura mater of rats under the effects of noise-vibration

The biorhythmologic changes of tissue basophils (mast cells) have been investigated of mater rats in frontal, temporal and occipital regions of dura mater during the noise-vibration stress. Local differences were found in biorythmological characteristics of tissue basophils before and after vibration. The investigated regions of dura mater after noise-vibration stress the magnitude of harmonics, mesor and the amplitude of fluctuations increased greatly. But, judging by their values, in the temporal region the rhythm stability was lower than that in the frontal and occipital. The tissue basophils of various regions of dura mater react in a different way to the noise-vibration stress.     

Aging and sex influence the permeability of the blood-brain barrier in the rat

The aim of the present study was to investigate the existence of aging- and sex-related alterations in the permeability of the blood-brain barrier (BBB) in the rat, by calculating a unidirectional blood-to-brain transfer constant (Ki) for the circulating tracer [14C]-alpha-aminoisobutyric acid. We observed that: a) the permeability of the BBB significantly increased within the frontal and temporo-parietal cortex, hypothalamus and cerebellum in 28-30 week old rats, in comparison with younger animals; b) in several brain areas of female intact rats higher Ki values (even though not significantly different) were calculated at oestrus than at proestrus; c) in 1-week ovariectomized rats there was a marked increase of Ki values at the level of the frontal, temporo-parietal and occipital cortex, cerebellum and brain-stem. One can speculate that aging- and sex-related alterations in the permeability of the BBB reflect respectively changes in brain neurochemical system activity and in plasma steroid hormone levels.     

Influence of surgical pain stress on the blood-brain barrier permeability in rats

Effect of surgical pain stress on the blood-brain barrier permeability was investigated in rats. The animals were divided into four groups: Group 1: control, Group 2: immobilization stress, Group 3: acute hypertension, Group 4: immobilization stress + surgical pain stress.Bilateral hid paw surgical wounds for cannulations were applied in animals' inguinal regions under diethyl-ether anesthesia, then the animals were awaken from anesthesia to produce surgical pain stress. Evans-blue was used as a blood-brain barrier tracer. There is no significantly blood-brain barrier breakdown after short-time immobilization stress, but after adrenalin hypertension blood-brain barrier permeability was increased especially on frontal and occipital cortices in 50% of the animals. Surgical pain stress increased blood-brain barrier permeabiliy in comparison to acute adrenalin-induced hypertension (p < 0.01). In surgical pain stress-induced animals distinct Evans-blue leakage was observed in the occipital, frontal and parieto-temporal cortices.     

The ECoG of rats with genetic catalepsy]

Electrographic study was carried out in Wistar rats and the rats of genetical catalepsy (GC) strain. In contrast to Wistar rats epileptiform activity was observed in ECoG of GC rats being enhanced at the transition to a cataleptic state. Analysis of spectra and coherence of EEG revealed the presence of interhemispheric brain asymmetry in all the rats. In some frequency bands in GC rats inversion of interhemispheric asymmetry was found, which had been characteristic for Wistar strain. The highest interhemispheric synchronization of biopotentials was observed in the frontal cortical areas in GC rats and in the occipital areas in those of Wistar strain.     

Spatial synchronization of potentials in the frontal zones of the brain during performance of nominative speech in children

Characteristics of spatial-temporal relations of the frontal zones potentials with those of other brain centres were studied in five- to six-year old children during naming of visually presented objects. EEG cross correlation analysis has shown that during visual perception of familiar objects the correlations of frontal areas with the interior pariental area of the left hemisphere are enhanced; the rhythms of the inferior parietal and occipital zones in the left hemisphere precede the potentials in the frontal area, while in the right hemispere synphasic relations are set up between the frontal and occipital zones. Naming the objects by the appropriate word as compared with rest and showing of the object, leads to enhancement of both intra- and interhemispheric correlations between potentials in the frontal zone and the inferior parietal and temporal zones. The frontal lobe rhythms begin to precede the inferior parietal and occipital potentials and form synphasic relations with the temporal and motor zone potentials in the left hemisphere.     

Neonatal cerebral cortical lesion abolishes the anxiolytic action of diazepam in adult rats: effects of location and extent of cortical lesion.

In our previous study, diazepam (DZP), a benzodiazepine receptor agonist, failed to suppress foot-shock-elicited ultrasonic vocalizations (USVs) in adult rats that had been neonatally lesioned in the neocortex. Because neonatal lesion of the neocortex did not influence the production of USVs, the presence of an anxiolytic mechanism of DZP is suggested apart from any anxiogenic mechanism in the brain. However, the previous study did not indicate any specific cortical regional lesions that impaired the normal development of the anxiolytic mechanism in the brain. The present study was undertaken in order to examine whether neonatal lesion of the neocortex, smaller and more localized than that in the previous study, abolishes the anxiolytic effect of DZP on foot-shock-elicited and air-puff-elicited USVs. A neonatal lesion about 2 mm diameter was made in the unilateral frontal cortex frontal to the hindlimb area or in the occipital cortex caudal to the hindlimb area. The attenuating effect of DZP on the USVs elicited by both aversive stimuli was found to be abolished only in the frontal cortex-lesioned rats. This finding indicates that the frontal cortex is likely to be specifically involved in the normal development of the benzodiazepine-anxiolytic mechanism in the brain.     

基于聚类分析方法的酒后人脑状态研究

目的:本文对酒精引起的人脑状态变化进行讨论。通过对客观记录的受试者摄入酒精事件的脑电图数据进行系统聚类分析,从而分析摄入酒精事件与21导联电极分类的关系,进而为有关人脑的其它研究提供实验和理论根据。方法:选取4名习惯用右手、健康的人进行实验,采用标准21个脑电极的10-20导联系统,获取受试者在安静闭眼和摄入一定量啤酒的2个事件的脑电图数据。然后进行数据分析。数据分析的方法是系统聚类分析方法。程序实现采用独立设计的脑电图分析工具箱和聚类分析程序。结果:对脑电图数据聚类分析后发现,未喝酒时脑电活动大致按前额部和中央、后头部、两侧得到3个聚类簇;摄入200毫升啤酒后,受试者P1和P2的大部分额部电极、中央部电极以及后头部电极聚类为一个簇,个别颞部、后头部电极聚类为一个簇,或单个电极独立为一簇,形成孤立点;摄入400毫升啤酒后,受试者P3和P4的大部分额极电极、额部电极、中央部电极以及后头部电极聚类为一个簇,个别额部、中央部、颞部单个电极独立为一簇,形成孤立点。结论:脑电活动对摄入酒精有显著反应。由于人在安静闭眼状态下,后头部记录到的α波较为显著,所以未喝酒时前后头部脑电信号相关性较弱,受试者前后头部的电极基本不在一个聚类簇中;摄入酒精后,受试者大部分额部、中央部和后头部电极聚类为一簇,即前后头部脑电信号的相关性增强,这说明在酒精的作用下,前头部α波增加,α波呈现扩大和增强的趋势。     

Electrocorticographic development of epileptogenic foci in the occipital region of the rat cerebral cortex

The development of cortical penicillin foci in the occipital region was studied in rats whose ages ranged from five days up to the adult age. The local application of penicillin induced the formation of an epileptogenic focus for the first time at the age of seven days. With advancing age, the amplitude of focal discharges increased, the duration of the individual components of the discharge shortened, its originally negative-positive configuration changed to a triphasic form and in the third week of life initial positivity, for a time, become the dominant component of the discharge. Projection of the discharges to the contralateral hemisphere was found to be inconstant in the second postnatal week, but appeared regularly from the age of 14 days. Synchronization of the discharges of two symmetrical foci was very poor in 7-day-old young, but improved noticeably by the 14th day; it was never complete, however, even in adulthood. The activity of symmetrical foci changed spontaneously to ECoG seizures, which were most common in 7-day-old young (in which ictal activity was usually not generalized, however) and were least frequent in 14-day-old animals. Focal discharges could not be reliably triggered by electrical stimulation of the contralateral cortex until the age of 18 days and later. The occipital part of the cortex develops somewhat later than the sensorimotor, frontal region, and during its development there also appeared phenomena which are not present in the frontal cortex.     

Fronto-cortical regulation of beta-endorphin actions in the rat

Ablation of the frontal neocortex markedly enhanced the antinociceptive and cataleptic actions of beta-endorphin injected into the lateral ventricle of rat brain. This enhanced response was not affected by simultaneous administration of cholecystokinin octapeptide (CCK-8). In sham-operated rats, however, CCK-8 suppressed the effects of beta-endorphin in a dose-related manner. Moreover, ablation of a similar amount of occipital neocortex did neither affect beta-endorphin actions nor the interactions of CCK-8.     

Glutathione peroxidase activity in surgical and autopsied human brains

Glutathione peroxidase (GSHPx) activity was assayed in normal cerebral gray and white matter samples obtained from frontal, temporal, occipital and parietal lobes during surgical approach to an underlying lesion, and also in normal autopsied human frontal gray and white matter. GSHPx was assayed by a 2 step enzyme reaction which was monitored by following the oxidation of NADPH at 340 nm. It was found that all the brain samples studied contained GSHPx activity. Parietal lobe appeared to have the lowest GSHPx activity compared to temporal, occipital or frontal lobes. Mean enzyme activity in autopsied samples was comparable to that in surgical material. However, considerable loss of activity was observed after 10 years of tissue storage at –80°C.This investigation was supported by the Verterans Administration.     

Change in the functional significance of structures of the cat brain as a result of reorganization of its activity

A study was carried out on 8 adult cats of functional role of the frontal, parietal and occipital parts of the neocortex, and also of the dorsal hippocampus, mediodorsal thalamic nucleus and caudate nucleus head, in realization of a delayed spatial choice (DSCh) before and after compensatory reorganizations of the brain activity caused by multiple electrical stimulation of the frontal part of the cerebral cortex. Compensatory reorganization led to a change of functional significance of these structures. While before this change the frontal cortex, hippocampus and mediodorsal thalamic nucleus were critically necessary brain areas for the realization of the DSCh, after it parietal and occipital cortical areas acquired such significance. The obtained data are discussed proceeding from the principle of the integrity in the brain activity.     

The EEG correlates of the erroneous identification of noise-masked visual stimuli]

Specific features of EEG coherence of a man-operator were revealed before the erroneous actions ("false alarm" and "signal omission") in the process of training to recognize masked visual stimuli. In persons with expressed alpha-rhythm at rest the "false alarms" were associated with the highest level of beta-frequency correlation in the frontal areas. Errors of the "signal omission" type were observed against the background of increased alpha-coherence in the frontal and occipital derivations. These features were more pronounced in the right brain hemisphere. The results suggest that the erroneous actions are predetermined by a specific state of the frontal brain regions, which participate in decision making, and are probably related with inadequate information transmission from the caudal regions to the frontal ones.     

The Cerebrocortical Areas in Normal Brain Aging and in Alzheimer's Disease: Noticeable Differences in the Lipid Peroxidation Level and in Antioxidant Defense

The markers of oxidative stress were measured in four cerebrocortical regions of Alzheimer's disease (AD) and age-matched control brains. In controls the levels of diene conjugates (DC) and lipid peroxides (LOOH) were significantly higher in the sensory postcentral and occipital primary cortex than in the temporal inferior or frontal inferior cortex. The antioxidant capacity (AOC) was highest in the temporal, and GSH in the frontal inferior cortex. The highest activity of superoxide dismutase (SOD) and catalase (CAT) was found in the occipital primary cortex. Compared with controls, significantly higher level of DC and LOOH and attenuated AOC were evident in AD temporal inferior cortex. In AD frontal inferior cortex moderate increase in LOOH was associated with positive correlation between SOD activity and counts of senile plaques. Our data suggest that in AD cerebral cortex, the oxidative stress is expressed in the reducing sequence: temporal inferior cortex > frontal inferior cortex > sensory postcentral cortex occipital primary cortex, corresponding to the histopathological spreading of AD from the associative to primary cortical areas.     

Structural Transformations of the Associative Cortex As the Morphological Base of the Development of Human Cognitive Functions from Birth to 20 Years of Age

The microstructure of the temporo-parieto-occipital subregion and the frontal area of the brain from birth to 20 years of age was studied using computer morphometry. These brain zones are involved in the higher integrative mechanisms of cognitive functioning in children, adolescents and young adults. Structural transformations of the cortex represent a stage-by-stage process. Each stage in the frontal and occipital associative zones has specific temporal limits and is characterized by the quantitative and qualitative specificity of the morphological changes at each of the system levels considered: neuronal, modular, and stratification. The structural modifications from birth to early adulthood are primarily associated with the final development of micro and macroassembles and their structural components, primarily, neurons of various types. The growth and differentiation of neurons involves heterochrony with respect to the terms and developmental rates in the frontal and occipital associative cortex. The terms of the most active synchronous postnatal structural modifications, occurring during the first year of life, during the years 2–3, 6–7, 9–10, and 13–14 were analyzed. It was shown, that local specialization of cellular ensembles at various levels is a consequence of the functional specialization of microensembles, involved in cortical information processing, including cognitive activity and other higher psychophysiological functions of the human brain.     

Creatine phosphokinase BB distribution in different structures of the human brain

Regional localization of creatine phosphokinase BB was studied in postmortem human brain and its stability was shown. The content of CPK BB in different brain structures was unequal: from 0.5 mcg/mg of protein in the occipital lobe and tuber cinereum to 4.5 mcg/mg in the frontal lobe. In the regional localization of CPK BB in the postmortem brain of schizophrenia patients, some changes in isoenzyme content were found as compared to the control group. The reduction of CPK BB concentration at schizophrenia was found in the frontal lobe (45%, P less than 0.001) and s. nigra (70%, P less than 0.001); the concentration was higher in the thalamus and occipital lobe (15%, P less than 0.001), as well as in the parietal lobe, cingulate gyrus, tuber cinereum, cerebellum cortex, inferior olive--50-80%, P less than 0.001.     

Changes in evoked potentials to light in the presence of lesions of the diencephalic and brainstem regions of the human brain

Evoked potentials (EPs) to light were studied in groups of patients with tumours of basal-diencephalic localization (24 patients) and at the brain-stem level (24 patients), in comparison with 11 normal subjects. In the first group, a decrease of amplitude and increase of response duration were found in the frontal cortical areas, with simultaneous reduction of intrahemispheric differences due to decrease of low-frequency components in the EP spectra by amplitude in fronto-central parts, and of alpha- and beta-frequencies in the occipital parts of the hemispheres. EP changes resulting from brain-stem tumors were more expressed than in the case of cerebellar tumors. In patients with foci causing a pronounced irritation of the brain-stem, a decrease in responses amplitude was observed accompanied by an amplitude lowering of delta- and theta-frequencies in EPs-spectra in the frontal, central and temporal leads, with no changes in the occipital leads. The obtained data testify to functional inequivalence and independence of different EP frequency components suggesting that the methods of studying the EP frequency structure are informative and efficient.     

Structure of the field of cerebral biopotentials and the latent period of the human motor response

An investigation was made into the statistical interconnection between the latency of human conditioned motor reaction to a flash and the spatial distribution of EEG correlation coefficients of eight cerebral areas in 10-second epoch preceding the stimuli. The greatest similarity of latency variations was observed with changes in the correlation relationships between EEG of the occipital, frontal and central areas of the hemisphere, contralateral to the reacting hand. Analysis of the structure of the brain biopotential field has shown that the probability of a more rapid reaction is greater if in the pre-stimulatory period there is a spatially coherent alpha-rhythm with nearly contraphasic correlations of oscillations in the frontal and occipital brain areas.     

Structural rearrangements of the cerebral cortex in children and adolescents

The cortical formations of the brain involved in visual functions (the occipital and temporo-parieto- occipital areas, the oculomotor area of the prefrontal cortex), as well as the motor cortex in the representation zone of the arm and the medial region of the frontal cortex adjacent to the limbic lobe, were studied in post-mortem material. The thickness of the cortex and cortical layer III, the sizes of pyramidal neurons, the specific volumes of neurons and intracortical vessels were studied in subjects of both sexes, from birth to the age of 20 years, at yearly intervals (103 observations) using histological techniques, computer morphometric and stereological analysis. The thickness of the cortex of the cerebral hemispheres was observed to intensively increase from birth to the age of 3 years in the occipital, temporo-parieto-occipital and prefrontal cortical areas involved in visual recognition processes. The increase in thickness of the cerebral cortex continues until the age of 6 in the occipital cortex and in the oculomotor area, until the age of 7 years in the temporo-parietooccipital area and the medial prefrontal area, and until the age of 8–9 years in the motor cortex. The sizes of pyramidal neurons increase until the age of 6 years in the motor cortex, until the age of 8 years on the medial surface of the frontal lobe, and until the age of 9–10 years in the temporo-parieto-occipital area and in the dorsolateral area of the prefrontal cortex. The specific volume of neurons and blood vessels in the cortex of the cerebral hemispheres decreases and the volume of intracortical fibers increases throughout the ascending ontogeny, which is manifested most intensively in the prefrontal cortex.