[Cellular and fibrillar organization of the locomotor regions of the brain stem in cats]. / Kletochnaia i volokonnaia organizatsiia lokomotornykh oblastei stvola mozga koshki.

Cellular and fibrillar organization of the hypothalamic (HLR) and mesencephalic (MLR) locomotor regions of the brain stem has been studied in cats by means of staining the nervous tissue after Nissl and Sokolyansky. Morphometric investigations of neurons in these regions has been performed in frontal and sagittal slices. Within the limits of the HLR ad MLR there are about 45,000 of neurons, which are organized as various nuclei, the MLR cells arranging in them more compactly in comparison to diffusely ++ scattering HLR neurons. Within the limits of the locomotor regions, together with the cells and powerful compact fasciculi of fibers in the tract passing, that is especially specific for MLR, there are also numerous diffusely ++ scattered fibers. A possible role of the neurons and the fibers passing in starting locomotion at activation of the locomotor areas of the brain stem is discussed.

[Descending neuronal projections to the lumbar segment of the spinal cord of cats]. / Niskhodiashchie neironnye proektsii na poiasnichnyi otdel spinnogo mozga koshki.

In the experiments, performed on cats by means of retrograde axonal horseradish peroxidase transport, localization of the sources of descending supra- and propriospinal projections to the area of the lumbar parts of the spinal cord, where the generator of locomotor movements is located. After local administration of horseradish peroxidase into the spinal cord, the greatest amount of the labelled neurons is observed in the ipsilateral reticular formation and in the Koelliker-Fuse nucleus. Comparison of the number of neurons, forming the descending projections from the I cervical up to the IV lumbar segments demonstrates an essential predominance of short propriospinal connections over the long, as well as over the supraspinal ones.

[Afferent projections of the bulbar locomotor region located in the medial reticular formation of the brain stem]. / Afferentnye sviazi bul'barnoi lokomotornoi oblasti, raspolozhennoi v medial'noi retikuliarnoi formatsii stvola mozga.

Afferent projections to the functionally identified bulbar locomotor region which is situated in the medial reticular formation were studied in cats and rats by means of horse-radish peroxidase technique. Cells of origin of such projections were found not only in hypothalamic and mesencephalic locomotor regions but also in the interstitial nucleus of Cajal and adjacent structures and in the ventral part of the caudate nucleus.

[An organizational analysis of the neurons forming the descending cortico-hypothalamic pathways]. / Analiz organizatsii neironov, obrazuiushchikh niskhodiashchie kortiko-gipotalamicheskie puti.

Quantitative assessment of spatial organization of cortical neurons forming descending fibre systems and hypothalamic structures has been made using technique of retrograde axonal transport of horseradish peroxidase. Heterogeneity of cortico-hypothalamic bonds is determined: the prefrontal cortex exerts a more pronounced effect on the hypothalamus as compared with other cortical areas of the limbic brain. Cortico-hypothalamic neurons form neuronal groups on different frontal levels of the prefrontal cortex and convolution of the cingulum, a form and orientation of the group being determined by the topography of dominating axonal systems running to the hypothalamus. There are various forms of cell associations in the frames of neuronal populations. Ensemble groupings of neurons may underlie the principle of organization of direct cortico-hypothalamic ways.

Afferent and efferent connections of brainstem locomotor regions: study by means of horseradish peroxidase transport technique.

Afferent and efferent connections of the hypothalamic and mesencephalic locomotor regions and also the bulbar locomotor strip were studied in cat using retrograde (horseradish peroxidase) transport technique. To study the sources of afferent projections, the enzyme microinjections were performed exactly into the same brain sites eliciting treadmill locomotion by means of electrical stimulation. When studying efferent projections horseradish peroxidase labeled neurons were revealed within locomotor regions after enzyme microinjections into different brain structures. Experimental data have shown that the hypothalamic and mesencephalic locomotor regions have mutual afferent and efferent projections with numerous brain areas including interconnections. Apart from the entopeduncular nucleus, the great number of different sensory nuclei are noted: among the sources of afferent projections are the nucleus tractus spinalis nervi trigemini, nucleus cuneatus, nucleus tractus solitarius and vestibular nuclei. In addition, after horseradish peroxidase injection into the mesencephalic locomotor region labeled neurons were found in the cochlear nuclei. Direct descending neuronal projections of the hypothalamic and mesencephalic locomotor regions are distributed mainly in the ipsilateral brainstem. Only a few of them reach the lumbar spinal cord. The most marked efferent projections of given regions are those to the brainstem reticular formation. After horseradish peroxidase injection into a functionally identified bulbar locomotor strip, labeled neurons were revealed in different stem regions mainly caudal to the enzyme injection site. The existence of a locomotor strip as an independent structural formation is called into question. When studying the locomotor region connections, the structural heterogeneity of these regions is revealed. Transitory fibers of ascending tracts are presumably within their limits side by side with neurons. The role of these fibers in stepping initiation by electrical stimulation of locomotor regions remains uncertain.

[Efferent projections of neurons of the mesencephalic locomotor region of the cat brain]. / Efferentnye proektsii neironov mezentsefalicheskoi lokomotornoi oblasti mozga koshki.

Efferent projections of mesencephalic locomotor region neurons were studied by means of horseradish peroxidase technique in cat. Ascending and descending projections of these neurons to different structures of the brain with predominant course to the brainstem reticular formation were traced. Some fibres passed through the bulbar and spinal locomotor strip. Mutual bilateral interconnections of the mesencephalic locomotor regions were observed.

[Afferent connections of the mesencephalic locomotor area of the cat brain]. / Afferentnye sviazi mesentsefalicheskoi lokomotornoi oblasti mozga koshki.

Afferent projections to the functionally identified mesencephalic locomotor region were studied in cat by means of the horse-radish peroxidase technique. Quantitative calculation of HRP-labelled neurons in the different brain structures after enzyme injections into mesencephalic locomotor region was made. Apart from the entopeduncular nucleus, different hypothalamic areas and substantia nigra, labelled neurons were found in ventral tegmental area, substantia grisea centralis, raphe and vestibular nuclei, nucleus of tractus solitarius and brainstem reticular formation. Neurons accumulating horse-radish peroxidase were found also in the brainstem sensory nuclei. This fact emphasized the structural heterogeneity of the mesencephalic locomotor region which includes neurons and passing fibers; both of them may be significant during locomotion elicited by the midbrain stimulation.

[Projections of neurons of the hypothalamic locomotor region to brain stem and spinal cord structures in the cat]. / Proektsii neironov gipotalamicheskoi lokomotornoi oblasti na struktury stvola i spinnogo mozga koshki.

Efferent projections of the hypothalamic locomotor region were studied by means of the horse-radish peroxidase technique. Labelled neurons in this region after HRP injections in different brain structures including lumbar spinal cord and other identified brainstem locomotor zones were found mainly ipsilaterally. The most considerable amount of labelled hypothalamic neurons was observed after HRP injections in the medial brainstem reticular formation and in the locus coeruleus area. The hypothalamic locomotor region also forms direct projections to the mesencephalic locomotor region and to the locomotor strip.

[Projection of forebrain structures of the cat to the hypothalamic locomotor area]. / Proektsii struktur perednego mozga koshki v gipotalamicheskuiu lokomotornuiu oblast'.

Descending projections of brain cortex and basal ganglia to the hypothalamic locomotor region were demonstrated in cat with horseradish peroxidase technique. Neurons projecting directly to the functionally identified locomotor region are dispersed in different gyri with predominance in areas 4 and 6 of the motor cortex. Such neurons are also located in entopeduncular nucleus. Massive cortico-and pallido-hypothalamic projections as a rule do not reach the most caudal hypothalamic divisions where the locomotor region is localized.

[Afferent brain stem connections of the hypothalamic locomotor area of the cat brain]. / Vnutristvolovye afferentnye sviazi gipotalamicheskoi lokomotornoi oblasti mozga koshki.

Afferent brainstem projections to the functionally identified hypothalamic locomotor region were studied in cat by means of the horse-radish peroxidase technique. Cells of origin of such projections were found bilaterally in the different brainstem structures. Most of these cells were found in sites of location of monoaminergic systems (nucleus reticularis lateralis, locus coeruleus, nucleus tractus solitarius, raphe nuclei, substantia grisea centralis) parabrachial and certain sensory nuclei of the brainstem. The hypothalamic locomotor regions have mutual bilateral interconnections.

[Horseradish peroxidase-labeled cells as sources of the spinoreticular and spinothalamic systems of the brain]. / Mechennye peroksidazoi khrena istochniki spinoretikuliarnykh i spinotalamicheskikh sistem mozga.

The cells of spinoreticular and spinothalamic fibrous systems of the cat brain were studied by the method of axone transmission of horse-radish peroxidase (HP). A dense accumulation of HP-labeled neurons establishing direct relations with the reticular formation and thalamus was seen in the upper segments of the spinal cord. In the lower segments these zones were confined to the medial part of the ventral horn and the intermediate zone of the gray matter. The neurons established direct connections with contralateral nuclei of the reticular formation as well as with the thalamus ipsi- and contralateral nuclei. Possible pathways of transmitting somatic and pain sensitivity are discussed.

[Laminar distribution of sources of ascending spinocerebral fiber systems in the spinal cord of cats]. / Laminarnoe raspredelenie v spinnom mozge koshki istochnikov voskhodiashchikh spinotserebral'nykh volokonnykh sistem.

Cells of origin of the spinobular, spinomesencephalic and spinothalamic tracts in the cat brain were identified by the retrograde horseradish peroxidase transport technique. A conclusion is made that neurons in laminae IV and V give rise to ascending fibres to the ipsilateral dorsal column nuclei and neurons in the lateral parts of laminae V and VI and in lamina VIII establish direct connections with the contralateral thalamus (CM, MD, CL) and reticular formation of the brain stem. Throughout the spinal cord the labelled neurons were present in the intermediate zone of both sides.

[Horseradish peroxidase labeled sources of the spinobulbar and spinothalamic fiber systems of the cat brain]. / Mechennye peroksidaznoi khrena istochniki spino-bul'barnykh i spino-talamicheskikh volokonnykh sistem mozga koshki.

A dense accumulation of horseradish peroxidase (HRP) positive neurons was found after bulbar HRP injections in the ipsilateral dorsal grey matter and in the intermediate zone on both sides. After thalamic injections the labelled neurons were located bilaterally in the ventral part of the intermediate zone. A conclusion is made that cells of the origin of the spinobulbar and spinothalamic tracts are located in the dorsal horn and in the intermediate zone of the spinal cord.