Method of Reduction Background Fluorescence in Human Fetal Brain Tissue and Quantitative Estimate of the Effect of Photobleaching.

We developed a method of reducing the background fluorescence of samples made from formalin-fixed and paraffin-embedded blocks of the brain of the second-trimester human fetuses. For reducing excess background fluorescence, the samples were subjected to photobleaching using an LED lamp with blue and red emission peaks in the range of visible spectrum in a construction of an original design. The decrease in the background autofluorescence was checked by measuring the intensity of the emitted background fluorescence of the samples and relative abundance of immunopositive structures after immunohistochemical staining. It was found that the proposed method reliably reduced the background fluorescence of the samples, which improved the quality of multicolor immunofluorescence images of the cerebral cortex.

Peculiarities of Cyto- and Chemoarchitectonics of Human Entorhinal Cortex during the Fetal Period.

We studied peculiarities of the structure of human entorhinal cortex at weeks 20-26 of gestation (10 hemispheres). The samples were Nissl-stained and immunohistochemically treated with antibodies to parvalbumin, calretinin, calbindin, and cytoskeleton proteins (MAP2 and N200). 3D-reconstruction of the entorhinal cortex from serial sections was performed, caudomedial and rostrolateral areas were isolated. Parvalbumin+ cells in layer I, discrete distribution of layer II cells with colocalization of MAP2 and calretinin at the border with layer I, and two sublayers Va and Vb with MAP2+ neurons were typical for the caudomedial area. Rostrolateral area was characterized by the homogenous layer II with big amount of cells, high density of MAP2+ neurons only in layer III, and the unique layer V. Reelin+ Cajal-Retzius cells and N200+ fiber plexus in layer I were observed in the caudomedial and rostrolateral areas of the entorhial cortex. Layer IV was represented by a cell-free desiccant.

Age-Specific Dynamics of Corpus Callosum Development in Children and its Peculiarities in Infantile Cerebral Palsy.

The age dynamics of corpus callosum development was studied on magnetic resonance images of the brain in children aged 2-11 years without neurological abnormalities and with infantile cerebral palsy. The areas of the total corpus callosum and its segments are compared in the midsagittal images. Analysis is carried out with the use of an original formula: proportion of areas of the anterior (genu, CC2; and anterior part, CC3) and posterior (isthmus, CC6 and splenium, CC7) segments: kCC=(CC2+CC3)×CC6/CC7. The results characterize age-specific dynamics of the corpus callosum development and can be used for differentiation, with high confidence, of the brain of children without neurological abnormalities from the brain patients with infantile cerebral palsy.

[AMYGDALA: NEUROANATOMY AND NEUROPHYSIOLOGY OF FEAR].

This work describes neuroanatomical and neurophysiological mechanisms of Pavlovian fear conditioning, focusing on contributions of the amygdala, a subcortical nuclear group, to control of conditioned fear responses. The mechanisms of synaptic plasticity at projections to the amygdala and within amygdala were shown to mediate the formation and retention of fear memory. This work reviews current data on anatomical organization of the amygdala, as well as its afferent and efferent projections, in respect to the role of the amygdala in auditory fear conditioning during which acoustic signals serve as the conditioned stimulus.

[Comparative MRI morphometric study of the corpus callosum at term and preterm infants].

A comparative morphometric analysis of MRI brain tomograms of term ant preterm born children was conducted. Common morphometric indexes and a novel quantitative parameter, a coefficient of corpus callosum (kCC), developed with regard to prenatal cortex ontogenesis pattern were applied to the study in order to get objective structural characteristics of the brain. All these quantitative indexes display anatomical features of the preterm brain. Reduced values of corpus callosum coefficient at preterm born children are known to associate with altered proportion between its rostral and caudal segments. A threshold coefficient value was established to differentiate preterm brain from the term one and it has proven its statistical significance.

[Features of human cortical pyramidal neurons development during second gestational trimester].

Prenatal ontogeny of human neocortex have distinctive features that make it unique. Experimental data obtained on animal models could not be easily extrapolated on human corticogenesis of middle and late gestational period. Our research was aimed at features of human cortical pyramidal neurons development within 16-26 gestational weeks. Material was obtained during legal autopsies. Neurons were marked using indirect immunofluorescence with primary antibodies against phosphorylated a nd dephosphorylated microtubule associated protein MAP2.Expression of this protein marks the beginning of dendrogenesis. Morphotype and position of neuron within embryonic cortical layers could be easily identified due to abundance of MAP2 in neuron body and dendrites. It was shown, that MAP2 positive neurons are identifiable in embryonic cortical layer eV as early as 18th gestational week. At 25th gestational week two populations of pyramidal neurons are apparent inside cortical plate. In addition to layer eV neurons that have had differentiated earlier, layer eIII neurons appears. According to fact that differentiating neurons are more vulnerable to damaging factors than neuroblasts and mature neurons, our results suggest that critical periods for cortico-cortical and corticofugal populations of pyramidal cells occurs at different stages of second gestational trimester.

Structural and immunochemical characteristics of the neuronal organization of field 4 of the sensorimotor cortex in cats.

Inhibitory interneurons in the cortex are regarded as an important intracortical module-forming factor. We report here our studies of the expression of three calcium-binding proteins in interneurons in the sensorimotor cortex of the cat. Calbindin-expressing non-pyramidal neurons were found to be distributed non-uniformly in layer III, forming large groups. Three-dimensional modeling showed that these groups formed continuous columns of width 400-1500 microm, which extended 6000-8000 microm mediolaterally both along the walls of the cruciate sulcus and on the free surfaces of the posterior and anterior sigmoid gyri. These data led to the hypothesis that these groups of inhibitory interneurons may create the conditions for selecting groups of efferent neurons within their areas and to recruit them into a single physiological act.

[Structural, immunohistochemical specifics of neuronal organisation of the field 4 of the cat sensorimotor cortex].

Inhibitory interneurons play important role as the intracortical module organizing factor. The study characterized calcium binding protein expressing inhibitory intermeurons of cat's motor cortex. Nonpyramidal calbindin expressing neurons were found in layer III of area 4. On saggital sections, they were distributed along layer III in uneven manner, forming groups that lasted 400-5000 mcm. To assess neuron groups placement, a 3D reconstruction was made. It was shown that the groups were forming uninterrupted strips 400-1500 mcm in width laying in mediolateral direction inside cruciate and on superior and posterior sigmoid gyri. It seems that such groups of inhibitory intemeurons in motor cortex could create conditions to select a pool of efferent neurons and connect them in order to carry out a single physiological act.

[Prenatal ontogenesis of the human brain cortex temporal area].

Prenatal ontogenesis of temporal areas of the human cortex was studied. In the fetal cortex at the gestational age of 16-18 weeks three zones can be distinguished: marginal zone (eI layer), cortex plate and subplate. At 20-26 weeks cortex plate is divided into following layers: eII, eIII, eIV, eV and eVI, with "efferent" complex of layers being wider than "associative" one. The subplate neurons are eliminated in the fetus at 27-33 weeks, when "associative" complex composes over 50 per cent of the cortex thickness. The subplate has been identified by positive correlation between layer eII and the upper subplate layer spu cell density.

[The level of metabolic activity (cytochrome oxidase) as an index of functional significance of tectofugal and thalamofugal channels of the reptilian visual system].

Using histochemical determination of activity of the mitochondrial oxidative enzyme cytochrome oxidase (CO) in brain structures, metabolic activity both in turtles and in lizards has been shown to be higher in centers of the tectofugal channel (the tectal stratum griseum centrale, SGC; nucleus pretectalis ventralis, Ptv; thalamic nucleus rotundus, Rot; telencephalic visual area of the anterior dorsal ventricular ridge, Advr) than in the thalamofugal channel centers (the thalamic nucleus geniculatus lateralis pars dorsalis, GLd; cortex dorsolateralis, Cxdl; and pallial thickening, Path) of the visual system. Some interspecies differences in distribution of the CO activity in the tectal, thalamic, and telencephalic visual centers between terrestrial and pond turtles and lizards were revealed. The obtained data confirm the idea on the dominating role of the tectofugal channel over the thalamofugal channel of the visual system in information processing and organization of the day-to-day behavior of reptiles.

[Cytochrome oxidase distribution in the normal cat midbrain and after unilateral enucleation (a histochemical study)]. / Raspredelenie tsitokhromoksidazy v verkhnikh kholmikakh kryshi srednego mozga koshki v norme i posle odnostoronnei énukleatsii (gistokhimicheskoe issledovanie).

Histochemical method of cytochrome oxidase demonstration was used to study its distribution in frontal sections of tectum of the midbrain in cat in normal conditions and after unilateral enucleation. Basic layers of this formation were demonstrated in normal conditions similar to those revealed using classical histological methods. After unilateral enucleation rostral, middle and caudal parts of superior colliculus were stained differently. Contra- and ipsilateral surface layers in rostral and caudal parts were stained also with different intensity. Alteration of lightly and intensely stained patches appeared in middle part. Peculiarities of staining in cytochemical cytochrome oxidase demonstration in superior colliculus of tectum of the midbrain in enucleated animals are likely to reflect peculiarities of this structure afferentially by retinotectal, geniculotectal and geniculocortical fibres.

[A comparative histochemical study of cytochrome oxidase activity in the somatosensory and auditory brain centers in the normal rat and after exposure to superhigh-frequency electromagnetic fields]. / Sravnitel'noe gistokhimicheskoe issledovanie aktivnosti tsitokhromoksidazy v somatosensornykh i slukhovykh tsentrakh mozga krysy v norme i posle vozdeistviia sverkhvysokochastotnykh élektromagnitnykh polei.

Using histochemical method mitochondrial cytochrome oxydase (CO) in acoustic and somatosensory centers of rat brain has been studied to reveal CO activity distribution in norm and after impulse-modulated high-ultra-high frequency influence. After ultra-high frequency influence the increase of enzymic activity in a number of regions of rat brain centers with relationship to processing ecologically important sensory signals is revealed.

[The structural-functional characteristics of the rostral sections of the neocortex in Chiroptera]. / Strukturno-funktsional'naia kharakteristika rostral'nykh otdelov neokorteksa rukokrylykh.

Studies have been made on the connections of rostral neocortex in bats in order to reveal connections with the structures of the auditory sensory system the existence of which is indicated by evident specific responses to ultrasound in the form of synchronization reaction. It was shown that dorsolateral parts of the rostral neocortex receive topically organized projections from the thalamic nuclei VPL and VL. Connections with the auditory cortex and suprageniculate nucleus are not evident. Afferents of the medial wall of the rostral cortex originate from the thalamic nuclei MD and AM. Possible pathways of auditory afferentation to the dorso-lateral part of rostral neocortex are discussed.

[Spatial organization and interneuronal relations in various areas of the neocortex in Cetacea]. / Prostranstvennaia organizatsiia i mezhneironnye vzaimootnoshe- niia nekotorykh oblastei neokorteksa kitoobraznykh.

The data on pyramidal neurons joining in the parietal and temporal areas of the dolphin neocortex by means of apical dendrites fasciculi are presented. The fasciculi also contain dendrites of spindle-like and stellate cells. The vertical fasciculi of the dendrites unite neurons of the layer V and of the sublayer III2. In the sublayer III1, after dichotonic division of the apical dendrites, fasciculi of the second order are formed, to them the dendrites of the pyramidal neurons of the sublayer III1 and the layer II join. Several forms of the interneuronal contacts have been revealed: axo-dendritic, axo-spinous and dendro-dendritic. Synaptic complexes of the converged and divergent types have been shown. A suggestion is made on formation of larger neuronal modules++, having common afferent entrance and demonstrating selectivity to the stimulus properties.

[Cortical projections of the medial geniculate body of the dolphin brain]. / Korkovye proektsii medial'nogo kolenchatogo tela mozga del'fina.

Cortical projections of the medial geniculate body have been studied in dolphin Phocaena phocaena by the method of anterograde degeneration of Fink--Heimer. For this purpose, in two animals a unilateral electrocoagulation of the thalamic auditory center has been performed. The caudal part of the microcellular nucleus of the medial-geniculate body has been stated to project ipsilaterally on the parietal, parietooccipital and temporal cortex. The oral part of this nucleus sends its fibres to the parietal and parietooccipital cortex. In the parietooccipital and temporal cortex auditory thalamic afferent fibres terminate predominantely in the layer III and in the upper third of the layer I. In the parietal cortex they terminate evenly in all the layers.