Temperature Asymmetry of the Rat Cerebral Hemispheres

The field potential and temperature of the cerebral cortex were studied in right-handed, left-handed, and ambidextrous rats. Temperature asymmetry of the cerebral hemispheres was revealed, which proved to differ in rats with different types of interhemispheric asymmetry: the interhemispheric temperature gradient was maximal in left-handed rats, minimal in right-handed rats, and intermediate in ambidextrous rats. Both parameters of energy metabolism (field potential and temperature of the cerebral cortex) correlated with one another, and the structure of these statistically significant correlations was different in right-handed, left-handed, and ambidextrous rats. It is suggested that the previously known types of interhemispheric asymmetry—biochemical, neurophysiological, and organoelement—are based on differences in the intensity of energy-consuming processes in the cerebral hemispheres.     

Modifications of the EEG Activity upon Lateralized Stimulation of the Visual Inputs to the Right and to the Left Brain Hemispheres by Light with Different Wavelengths

In 80 healthy humans, we studied changes in the frequency spectrum and values of the relative spectral coefficients for subsequent 1-Hz-wide frequency bands under conditions of simultaneous lateralized stimulation of the retinal zones, which form receptive fields for the right- and for the left-brain hemispheres; light of different colors was used for stimulation. We found that reactions of the right and left hemispheres to such stimulations demonstrated obvious specificity; spatial characteristics of these reactions were obtained. Changes in the values of most corresponding spectral coefficients in the hemispheres usually had similar directions and demonstrated similarity in their intensities, which is indicative of a complementary pattern of the interhemispheric interaction. Reciprocal changes in the corresponding spectral coefficients in the hemispheres were observed more rarely. Modifications of EEG upon red-green stimulations of different polarity were found to be similar, which can be a manifestation of the moderating influence of the right hemisphere on the left one.     

The functional testing of the interhemispheric asymmetry in the spatial organization of rabbit cortical potentials]

Interhemispheric asymmetry was studied of spatial-temporal potentials organization (STPO) of the cortex in non-fixated animals in the states of deep rest, behavioural activity and in the transition period between them. Despite the intrahemispheric differences of the STPO in each of these states, interhemispheric divergences in the character of reconstructions of momentary topograms of the cortical potentials, recorded at 24-channels leading, are limited by 35% of the epoch analysis time. Comparison of the dynamics of intrahemispheric changes of topograms of cortical potentials in the left and right hemispheres in the states of rest and activity revealed a narrowing of temporal period of the absence of resemblance in reconstructions of successive topograms of the left and right hemispheres in comparison with transition processes. In the phase of rest the interhemispheric conjugation of spatial reconstructions in topograms became lowered mainly because of the disturbances of monotony of changes of their reliefs in one of the hemispheres in turn. In the active phase, deviations from STPO of the cortex, characteristic of the state of rest, were met more frequently in the right hemisphere; in that case oscillations of the topograms general mean level connected with the activity of non-specific activating subcortical brain system acquired a significant role in regulation of interhemispheric relations. Presence of interhemispheric resemblance of reconstructions of topograms reliefs in the active phase, despite the tendency to its lowering in comparison with the rest, testifies to the contribution also of the intracortical processes to the interhemispheric spatial synchronization of the cortical potentials in this state.     

Neuronal architecture of the central complex in Drosophila melanogaster

Summary On the basis of 1200 Golgi-impregnated brains the structure of the central complex of Drosophila melanogaster was analyzed at the cellular level. The four substructures of the central complex — the ellipsoid body, the fanshaped body, the noduli, and the protocerebral bridge — are composed of (a) columnar small-field elements linking different substructures or regions in the same substructure and (b) tangential large-field neurons forming strata perpendicular to the columns. At least some small-field neurons belong to isomorphic sets, which follow various regular projection patterns. Assuming that the blebs of a neuron are presynaptic and the spines are postsynaptic, the Golgi preparations indicate that small-field neurons projecting to the ventral bodies (accessory area) are the main output from the central complex and that its main input is through the large-field neurons. These in turn are presumed to receive input in various neuropils of the brain including the ventral bodies. Transmitters can be attributed immunocytochemically to some neuron types. For example, GABA is confined to the R1–R4 neurons of the ellipsoid body, whereas these cells are devoid of choline acetyltransferase-like immunore-activity. It is proposed that the central complex is an elaboration of the interhemispheric commissure serving the fast exchange of data between the two brain hemispheres in the control of behavioral activity.     

The dynamics of the brain heat fields of rats in the late postresuscitation period during stress]

By thermoencephaloscopy method the temperature relief of the rats cerebral cortex was studied after the clinical death and reanimation. The rehabilitation of the animals neurological status was completed in 1-2 days. In the remote postresuscitation period (up to 2 months), expressed disturbances were revealed of the background thermomaps and of thermal reactions of the cerebral hemispheres, evoked by the stress influence. Pathologic mosaics of thermal characteristics was revealed in conditions of relative rest and disturbance of dynamics of the brain temperature reactions and the character of interhemispheric asymmetries at stress influence. Individual character is pointed out of postreanimative pathology, which is manifest both in the background thermomaps and after the functional load. The results of the studies suggest the importance of individual approach in rehabilitation therapy of postreanimative disease.     

Characteristics of interhemispheric relationships in the absence or presence of a skill

A comparative analysis of the time and amplitude characteristics of the negative N200 and positive P300 components of visual evoked potentials recorded at symmetric points of the frontal, parietal, temporal, and occipital areas of the right and left hemispheres of the cerebral cortex has been performed in subjects with or without the skill of operating a computer. Subjects inexperienced in an operator’s work exhibited an interhemispheric difference in the time and amplitude characteristics of the studied components. In subjects that had the skill of operating a computer, the interhemispheric difference was little, which suggests that the cortex plays only a small role in the cerebral control of this activity.     

The ECM Moves during Primitive Streak Formation—Computation of ECM Versus Cellular Motion

To generate complex bilateral motor patterns such as those underlying birdsong, neural activity must be highly coordinated across the two cerebral hemispheres. However, it remains largely elusive how this coordination is achieved given that interhemispheric communication between song-control areas in the avian cerebrum is restricted to projections received from bilaterally connecting areas in the mid- and hindbrain. By electrically stimulating cerebral premotor areas in zebra finches, we find that behavioral effectiveness of stimulation rapidly switches between hemispheres. In time intervals in which stimulation in one hemisphere tends to distort songs, stimulation in the other hemisphere is mostly ineffective, revealing an idiosyncratic form of motor dominance that bounces back and forth between hemispheres like a virtual ping-pong ball. The intervals of lateralized effectiveness are broadly distributed and are unrelated to simple spectral and temporal song features. Such interhemispheric switching could be an important dynamical aspect of neural coordination that may have evolved from simpler pattern generator circuits.     

Rapid interhemispheric switching during vocal production in a songbird

To generate complex bilateral motor patterns such as those underlying birdsong, neural activity must be highly coordinated across the two cerebral hemispheres. However, it remains largely elusive how this coordination is achieved given that interhemispheric communication between song-control areas in the avian cerebrum is restricted to projections received from bilaterally connecting areas in the mid- and hindbrain. By electrically stimulating cerebral premotor areas in zebra finches, we find that behavioral effectiveness of stimulation rapidly switches between hemispheres. In time intervals in which stimulation in one hemisphere tends to distort songs, stimulation in the other hemisphere is mostly ineffective, revealing an idiosyncratic form of motor dominance that bounces back and forth between hemispheres like a virtual ping-pong ball. The intervals of lateralized effectiveness are broadly distributed and are unrelated to simple spectral and temporal song features. Such interhemispheric switching could be an important dynamical aspect of neural coordination that may have evolved from simpler pattern generator circuits.     

Characteristics of the interhemispheric EEG relationships in assessing the functional state of the human brain

In healthy subjects (11 right-handed men) reorganization was studied of intra- and interhemispheric correlation of the electrical brain activity at transition from the state of alertness to drowsiness. At the lowering of alertness level, the coherence of hemispheres symmetrical points changed not abruptly, with a tendency towards an increase at differently directed character of changes of combinations of separate physiological rhythms ranges. Comparison of the EEG coherence changes within the right and left hemispheres revealed a greater reactivity of the left (dominant) hemisphere. The reduction of the predominance (observed in the dominant hemisphere in alertness) of the degree of EEG conjunction, at transition to drowsiness, leads to smoothing of interhemispheric asymmetry in the organization of electrical brain processes.     

Post-radiation effect on the interhemispheric asymmetry in EEG and thermography characteristics

Complex analysis of EEG and thermographic parameters carried out in 10 healthy subjects and 34 patients, Chernobyl clean-up participants revealed a correlation between EEG and brain temperature changes in the baseline state and during mental arithmetic. During cognitive activity the maximal increase in the average EEG coherence and temperature shifts in healthy subjects were observed in the left frontotemporal and right parietotemporal areas. In patients changes in both parameters under study were most pronounced, the interhemispheric relations were impaired. The visual analysis revealed "flat" and "hypersynchronous" EEG types in patients. The dominant pathologic activity in the betal range indicative of mediobasal and oral brainstem lesions was characteristic of the flat EEG. This type of activity was observed in 60% of patients. In these cases, a general decrease in EEG coherence and temperature was most pronounced in the left hemisphere. The hypersynchronou EEG type (40% patients) was characterized by paroxysmal activity in the theta and alpha ranges suggesting diencephalic brain lesions. In these cases, EEG coherence and temperature were more variable; changes in the right hemisphere were significant, be it increase or decrease. Our complex approach to investigation of brain activity in different aspects seems to be promising in estimation of the brain functional state both in healthy persons and patients in remote terms after exposure to radiation. The specific hemispheric temperature changes revealed in Chernobyl patients especially during cognitive activity can be the sequels of postradiation disorders of vascular neuro-circulation. The EEG findings suggest subcortical disorders at different levels (diencephalic or brainstem) and functional failure of the right or left hemispheres in remote terms after exposure to radiation.     

The significance of interhemispheric asymmetry in the development of compensatory processes in the human brain

For more precise definition of the role of hemispheric interconnections in mechanisms of human CNS compensation the intercentral relations of the electrical activity of the left and right cerebral hemispheres were studied on physiological model of focal interhemispheric asymmetry. Spectral-coherent EEG characteristics of 36 patients with tumoral damage of one hemisphere were studied in condition of chronic (prior to operation) and acute (early terms of postoperative period) brain decompensation. In was shown that the reorganization of the structure of the EEG intercentral relations correlated with definite stages of CNS compensatory processes and that the character of hemispheric interconnections depended on the lateralization of the damage focus. The primary role was revealed of the degree of the left (dominant) hemisphere preservation in restoration of normal pattern of the interhemispheric asymmetry of the coherence of human brain electrical processes.     

Pattern of changes in species diversity,structure and dynamics of forest ecosystems along latitudinal gradients in East Asia

We examined effects of seasonality of climate and dominant life form (evergreen/deciduous, broad-leaf/coniferous) together with energy condition on species diversity, forest structure, forest dynamics, and productivity of forest ecosystems by comparing the patterns of changes in these ecosystem attributes along altitudinal gradients in tropical regions without seasonality and along a latitudinal gradient from tropical to temperate regions in humid East Asia. We used warmth index (temperature sum during growing season, WI) as an index of energy condition common to both altitudinal and latitudinal gradients. There were apparent differences in patterns of changes in the ecosystem attributes in relation to WI among four forest formations that were classified according to dominant life form and climatic zone (tropical/temperate). Many of the ecosystem attributes—Fishers alpha of species-diversity indices, maximum tree height and stem density, productivity [increment rate of aboveground biomass (AGB)], and population and biomass turnover rates—changed sharply with WI in tropical and temperate evergreen broad-leaved forests, but did not change linearly or changed only loosely with WI in temperate deciduous broad-leaved and evergreen coniferous forests. Values of these ecosystem attributes in temperate deciduous broad-leaved and evergreen coniferous forests were higher (stem density was lower) than those in tropical and temperate evergreen broad-leaved forests under colder conditions (WI below 100°C). Present results indicate that seasonality of climate and resultant change in dominant life form work to buffer the effects of energy reduction on ecosystem attributes along latitudinal gradients.     

Brain asymmetry in phospholipid polar head group metabolism: Parallel in vivo and in vitro studies

Phospholipid content and³²P-incorporation have been studied in individual rat cerebral hemispheres. The total phospholipid content was 44.9±0.9 and 47.9±1.3 mol lipid P/100 mg protein for the right and left hemispheres respectively. Individually, only sphingomyelin was significantly (about 30%) higher in the left hemisphere. Metabolic experiments have been conducted in vivo using i.p. injection of³²P and following its incorporation into total and individual phospholipids in each cerebral hemisphere. Higher incorporations were attained by phosphatidate and phosphatidylinositol-4,5-bisphosphate (PIP₂) in the left cerebral hemisphere than in the right. In an attempt to determine whether phospholipid metabolism is also lateralized in specific subcellular compartments related with the neurotransmission process, we have studied in vitro the [³²P] incorporation into phosphoglycerides of synaptosomal fractions obtained from each cerebral cortex. The precursor was taken up differently by the two cerebral cortex preparations, resulting in different profiles of distribution among lipids. In addition, the kinetics of lipid labeling showed higher rates of³²P-incorporation in fractions derived from the left cerebral cortex, mainly in PIP and PIP₂, These results are interpreted to indicate that several enzymes involved in lipid metabolism are modulated to a different extent in the two hemispheres.     

Spectral-correlation characteristics of the electrical activity of the brain of the rabbit in a state of calm wakefulness

Inter- and intrahemispheric relations of electrical activity of the pre-motor, sensorimotor (representation of forelimb and blinking) and visual zones of rabbit's cerebral cortex in calm alertness was studied by method of spectral-correlative analysis. Mean coherence levels of the EEG of tested hemispheric symmetric points and symmetric pairs of leads in the left and right hemispheres were characterized by a high temporal stability in the state of calm alertness and during sensory stimulation. A comparison of mean coherence values of EEG in symmetric leads, revealed a tendency to left-side dominance of statistical bonds of electrical processes. A tendency was shown towards interhemispheric asymmetry by mean parameters of EEG power spectra: the left hemisphere of the rabbit is characterized by a lower mean frequency of electrical activity and a more narrow effective frequency of the spectrum.     

Physiological Criteria of Endurance in Athletes

The main bioenergetic qualities—the alactic anaerobic, glycolytic anaerobic, and aerobic potentials—are the main factors of endurance in athletes. These physiological properties may be estimated by three main parameters: power, capacity, and energy efficiency. The specific expression of endurance in athletes is determined by the ratio between these bioenergetic parameters. It has been found that the aforementioned criteria of endurance are expressed in different forms in the cases of critical modes of muscular activity and considerably affect performance in representatives of cyclic sports.     

Role of the Right- and Left-Hemispheric Structures in Speech and Memory Formation in Children

The role of structures of the left and right cerebral hemispheres in formation of speech function and memory was studied on the basis of complex examination of children with developmental speech disorders. On the basis of EEG estimation of the functional state of the brain, children were classified in two groups depending on the side of localization of changes in electrical activity: those with local changes in electrical activity in the left hemisphere (group I) and those with changes in the right hemisphere (group II). The medical history suggested that the observed features of topography of local changes in electrical activity were linked with the character of prenatal and labor complications and their consequences leading to embryo- and ontogenetic disorders in development of different brain regions. Comparison of the results of neuropsychological examination of the two groups showed that different regions of the brain cortex of both the left and right hemispheres are involved in speech formation. However, a specific role of the right hemisphere in formation and actualization of automatic speech series was revealed. It was suggested that the integrity of gnostic functions of the right hemisphere and, primarily, the spatial organization of perception and movements is a necessary factor of development of auditory–speech and nominative memory.     

Fundamental Causes of the Global Patterns of Species Range and Richness1

Global patterns of species range and richness are a consequence of many interacting factors, including environmental conditions, competition, geographical area, and historical/evolutionary development. Two widely studied global patterns of distribution are the latitudinal and elevation gradients of species range and richness. The fundamental mechanisms by which environment and physiology of the plants themselves interact to generate global-scale correlations between increased species range or decreased species richness and latitude/elevation have not previously been established. This paper develops the hypothesis that the primary climatic variables determining global-scale gradients in ectotherm species range and richness are temperature (T) and temperature variability (T), and that the primary physiological variable defining adaptation of ectotherms to temperature is respiratory energy metabolism. This hypothesis is based on a postulate that adaptation of ectotherms to latitudinal/altitudinal gradients of T and T leads to corresponding gradients in properties of energy metabolism. The gradients of metabolic properties give rise to gradients of species range and richness that are observed on a global scale. We demonstrate that natural selection results in ectotherms with metabolic properties matched to their environment and that energy use efficiency and the temperature range allowing growth are inversely related. Thus, opposing selective pressures to increase metabolic energy-use-efficiency or to increase the probability of surviving climate extremes control adaptation of ectotherms to climate. The principles developed in this paper yield fundamental laws of ecology that allow calculation of the contributions of global temperature patterns to the formation of gradients of species range and diversity. Relative values of richness and range are calculated solely from data on abiotic variables. Predictions agree with known patterns of ectotherm distribution.     

Free amino acids in synaptic vesicles isolated from the cerebellum and cerebral hemispheres of control and neonatally X-irradiated rats

X-irradiation of the rat brain (1000R, at two days of age), suppresses the normal age-related increase in the weight of the cerebellum and cerebral hemispheres and influences amino acid levels. The decrease in glutamic acid concentration, particularly in the cerebellum, supports the previously advanced proposition that this amino acid may be associated with, or may be the transmitter of, the rat cerebellar granule cells. Subfractionation of the cerebellar tissue reveals that the decrease in the glutamic acid level consequent to the loss of granule cells, is reflected in the cytoplasmic fraction but not in the synaptic vesicle subfraction, where glutamic acid was increased. The reduced weight gain in the cerebral hemispheres after irradiation, is accompanied by a significant decrease of aspartate in the cytoplasmic fraction, changes which suggest that a specific cell type, with aspartic acid as its neurotransmitter (possibly in the hippocampus), may also be radiosensitive in the early postnatal period. In contrast, in the synaptic vesicle fraction from cerebral hemispheres, all free amino acids, with the exception of glutamine, increased significantly. Overall, the changes in free amino acid concentration induced by X-irradiation in the cytoplasmic fraction in both brain regions studied are opposite to those found in the synaptic vesicle fraction and although they may indicate changes in specific cell populations, as proposed above, they could also reflect changes in cellular compartmentalization and metabolism or changes in the relative axonal arborization of the affected regions.Special Issue dedicated to Dr. Elizabeth Roboz-Einstein.     

Interhemispheric Functional Connectivity and Its Relationships with Clinical Characteristics in Major Depressive Disorder: A Resting State fMRI Study

Background

Abnormalities in large-scale, structural and functional brain connectivity have been increasingly reported in patients with major depressive disorder (MDD). However, MDD-related alterations in functional interaction between the cerebral hemispheres are still not well understood. Resting state fMRI, which reveals spontaneous neural fluctuations in blood oxygen level dependent signals, provides a means to detect interhemispheric functional coherence. We examined the resting state functional connectivity (RSFC) between the two hemispheres and its relationships with clinical characteristics in MDD patients using a recently proposed measurement named “voxel-mirrored homotopic connectivity (VMHC)”.

Methodology/Principal Findings

We compared the interhemispheric RSFC, computed using the VMHC approach, of seventeen first-episode drug-naive patients with MDD and seventeen healthy controls. Compared to the controls, MDD patients showed significant VMHC decreases in the medial orbitofrontal gyrus, parahippocampal gyrus, fusiform gyrus, and occipital regions including the middle occipital gyrus and cuneus. In MDD patients, a negative correlation was found between VMHC of the fusiform gyrus and illness duration. Moreover, there were several regions whose VMHC showed significant negative correlations with the severity of cognitive disturbance, including the prefrontal regions, such as middle and inferior frontal gyri, and two regions in the cereballar crus.

Conclusions/Significance

These findings suggest that the functional coordination between homotopic brain regions is impaired in MDD patients, thereby providing new evidence supporting the interhemispheric connectivity deficits of MDD. The significant correlations between the VMHC and clinical characteristics in MDD patients suggest potential clinical implication of VMHC measures for MDD. Interhemispheric RSFC may serve as a useful screening method for evaluating MDD where neural connectivity is implicated in the pathophysiology.     

Characteristics of the benzodiazepine receptors in rats with different predispositions to the development of experimental alcoholism

A study was made of the density and affinity of benzodiazepine receptors in the cortex of the cerebral hemispheres and hippocampus of rats with different predisposition to alcohol consumption. No differences were revealed in the parameters under study in animals with varying duration of ethanol anesthesia and in rats after voluntary consumption of ethanol for 3.5 and 10 months. In a state of abstinence rats with physical dependence manifested a dramatic decrease in the density and affinity of benzodiazepine receptors in the cortex of the cerebral hemispheres. No changes described were detected in the hippocampus. The role of benzodiazepine receptors in the development of abstinence is discussed.