[Effect of 6-hydroxydopamine administration to newborn female rats and sex differentiation of the brain]. / Effecty vvedeniia 6-gidroksidofamina novorozhdennym krysiatam-samkam i polovaia differentsiatsiia mozga.

Remote effects of neonatal 6-hydroxydopamine (6-OHDA) combined with testosterone propionate (TP) and alone were compared to ultrastructure of catecholaminergic terminals of the median eminence and hypothalamic catecholamine (CA) content in the critical period of sexual differentiation of the brain. It is suggested that inability of 6-OHDA to prevent TP-induced anovulatory sterility is connected with the preserved hypothalamic CA levels and a lack of significant degenerative changes in CA-ergic terminals in the median eminence.

[Excitation and inhibition processes in the neurons of the thalamic motor nuclei of normal cats and following an N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced lesion of the nigrostriatal dopaminergic system]. / Protsessy vozbuzhdeniia i tormozheniia v neironakh motornykh iader talamusa koshek v norme i posle porazheniia nigrostriatnoi dofaminergicheskoi sistemy, vyzvannogo N-metil-4-fenil-1,2,3,6-tetragidropiridinom.

Peculiarities of excitation and inhibition evoked in motor thalamic nuclei (VA-VL) neurons by electrical stimulation of red nucleus were studied on intact cats and after injection of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 5 mg/kg i.m., p.d. during five days). Two days after the last injection as much as 48% of nigral neurons were destroyed and the content of dopamine in the caudate nucleus fell to 30% as compared to intact animals. Before acute experiments all cats were anaesthetized with ketalar and immobilized with myorelaxine. It was found that MPTP injections caused a decrease of the inhibition duration and effectiveness in relay and nonrelay VA-VL neurons. The inhibition deficiency was accompanied by shortening of latencies of orthodromic responses evoked by red nucleus stimulation and facilitation of antidromic spikes invasion into somata of relay neurons after motor cortex stimulation. It was suggested that the reduction of GABAergic nigro-thalamic influences modulated by dopamine underlay the developing deficiency of inhibition.

[Cholinergic neurons in chronically isolated associative cortical slab of the cat]. / Kholinergicheskie neirony v khronicheski izolirovannoi poloske assotsiativnoi kory mozga koshki.

A histochemical acetylcholinesterase reaction has been used to find a few short-axon and long-axon cholinergic interneurons in the chronically isolated associative cortical slab of the cat three weeks after its isolation. Short-axon neurons are located in layers II-VI and are medium-sized and mainly spindle shaped. Their axons form synaptic terminals on the pyramidal and stellate neurons of the isolated slab. Characteristic location of cholinergic terminals on the soma and proximal parts of dendrites of cholinoceptive neurons is observed. Pyramidal cholinoceptive cells are attributed to non-cholinergic neuron type, while stellate cholinoceptive neurons may be both the cholinergic and the non-cholinergic ones. Long-axon cholinergic interneurons of various shape and size are distributed in layers I and VI. Axons of these cells establish intracortical connections beyond the isolated slab and run within the fibres of the first and subcortical layers.

[Various responses of neurons of the caudate nucleus in alert cats to visual stimulation]. / Raznoobrazie reaktsii neironov khvostatogo iadra bodrstvuiushchei koshki na zritel'noe razdrazhenie.

Activity of sixty two neurons of the caudate nucleus to the visual stimuli were recorded in awake cats. It was found that most (52%) of tested neurons gave visual responses of sensory type evoked by the appearance of light stimulus in the visual field and only 11% of them were of the motor type related to the guided eye movement to the target. About a quarter of neurons responded to biologically significant objects revealing nonspecific responses. Several types of visual responses could be recorded from the same neuron. The data obtained permit supposing the presence of several parallel pathways for afferent visual influences on the caudate nucleus.

[Rubro-caudate projections in the cat]. / Rubro-kaudatnye proektsii u koshek.

A few neurons projecting to the caudate nucleus were found in the cat red nucleus by the horse-radish peroxidase (HRP) method. Rubro-caudate neurons were observed both in the magnocellular and parvocellular parts of the red nucleus. Organization of the reciprocal connections of red nucleus and striopallidal system is discussed.

[Pathways of visual and auditory information transmission in the caudate nucleus of the cat]. / Puti peredachi zritel'noi i slukhovoi informatsii v khvostatoe iadro koshki.

Visual and auditory projections to the caudate nucleus were studied in cat by combination of the HPR method and experimental degeneration of retinal axons. It was shown that visual information comes to the caudate nucleus not only through the well-known polysynaptic pathways from the cerebral cortex, but also through both oligosynaptic (via pulvinar, lateroposterior nucleus, suprageniculate nucleus and nucleus limitans of the thalamus) and disynaptic pathways (via medial and lateral terminal nuclei of the accessory optic tract, pulvinar, pretectum, intermediate superior colliculus layer, supraoptic nucleus) some of which were found for the first time. Direct retinal inputs to the suprageniculate nucleus were found. Additional sources of auditory information to the caudate nucleus were revealed being as follows: the dorsal nucleus of parvocellular division of the medial geniculate nucleus, deep superior colliculus layer, dorsal and ventral nuclei of the lateral lemniscus. Physiological significance of the revealed pathways for the possible transmission of visual and auditory impulses and a new principle of organization of sensory inputs to the caudate nucleus are discussed.

[Projections of the neurons of the medial terminal nucleus of the accessory optic tract to the caudate nucleus of the cat detected by the combined methods of retrograde axonal transport and experimental degeneration]. / Proektsii neironov medial'nogo terminal'nogo iadra dobavochnogo opticheskogo trakta k khvostatomu iadru u koshki, vyiavliaemye pri sochetanii metodov retrogradnogo aksonnogo transporta i éksperimental'noi degeneratsii.

Projections of neurons of the medial terminal nucleus of the accessory optic tract receiving direct retinal inputs to the head and body of caudate nucleus are shown in cat by the retrograde axonal transport of horseradish peroxidase and experimental degeneration. These projections are mainly ipsilateral and uniformly distributed in the above mentioned parts of the nucleus. The neurons of the medial terminal nucleus establishing synaptic connections with caudate neurons have different shapes and sizes (from 20 X 10 microns to 37.5 X 18 microns) and are located both in the ventral and dorsal parts of the nucleus. Conclusions are made about functional significance of these projections in the regulation of the muscular tension.

[GABA-ergic structures in intact and chronically isolated association cortex of the cat brain (field 5)]. / GAMK-ergicheskie struktury v intaktnoi i khronicheski izolirovannoi assotsiativnoi kore mozga koshki (pole 5).

Distribution of GABAergic structures in intact and neuronally isolated associative cortex (field 5) of the cat was studied using histochemical GABA-transaminase reaction two and three weeks after isolation. An overwhelming majority of GABAergic fibres of the neuropile and synaptic terminals were found to be formed by axons of few GABAergic interneurons. Only a small portion of them belongs to afferent axons of the extracortical origin. GABAergic interneurons can be divided into short-axon ones, making contacts within the isolated slat, and long-axon neurons forming horizontal connections with more distant cortical neurons. GABAergic axons give numerous projections to the soma and proximal parts of dendrites of many pyramidal neurons, containing no GABA-transaminase, and of stellate neurons which are of GABAergic and non-GABAergic mediatory nature. It is suggested that the influence of some GABAergic neurons on the others may ensure intracortical spatial regulation of inhibitory processes.

[Cholinergic structures in the auditory area of the cerebral cortex in the cat (zone AI)]. / Kholinergicheskie struktury v slukhovoi oblasti kory mozga koshki (zona AI).

Histochemical reaction to AChE was used to reveal the network of cholinergic varicose fibres in the neuropile of different cortical layers. Its density was maximal in layer I and deeper, and minimal in layers II and III. Among neurons of zone AI few stellate neurons located in layers II-VI are cholinergic. Axons of some stellate neurons terminate on adjacent neurons, axons of a part of layer VI neurons travel to the subcortical layer of the associative arcuate fibres. Cholinergic terminals are located on the soma and proximal parts of dendrites of neurons most of which contain no acetylcholinesterase. Such cholinoceptive neurons of various size and shape are found in all cortical layers.

[Intrinsic cholinergic components in the cholinergic innervation of the auditory cortex in the cat (zone AI)]. / Sobstvennye kholinergicheskie komponenty v kholinergicheskoi innervatsii slukhovoi kory mozga koshki (zona AI).

Neuronally isolated auditory cortical slabs (zone Al) of cat were studied using histochemical AChE reaction 3 days and 1, 2, 3 weeks after isolation. Following structures were observed: cholinergic long-axon associative neurons responding to the cortex isolation by retrograde degeneration and AChE hyperreaction (Cajal-Retzius cells of layer I and neurons of layer VI whose axons travel to the subcortical layer of the associative fibres); cholinergic short-axon associative cells of layers II-VI, which retain normal structure and moderate AChE activity after isolation; their axon collaterals terminate on neighbouring neurons; short-axon neurons are more numerous in deeper layers of the cortex; on the whole they predominate over the long-axon associative neurons; cholinoceptive cells (pyramidal and stellate) were found with cholinergic terminals on the soma and proximal parts of the dendrites; these terminals were formed by associative cell axons. Cholinoceptive neurons occurred more frequently in deeper layers of the cortex.

[Neuronal composition and interneuronal connections of field 5 of the parietal association cortex of cats]. / Nironnyi sostav i mezhneironnye sviazi polia 5 temennoi assotsiativnoi oblasti kory mozga koshki.

Field 5 of the cat neocortex was studied by the Golgi method. Characteristic features here are as follows: predominance of pyramidal cells in layers II-III and existence of large forms (40X26 micron) among them; single and clustered giant pyramidal neurons (70X23 micron) in layer V; large (25-30 micron in diameter) and giant (40-45 micron in diameter) stellate cells with radial dendrites, single or gathered in groups, in layers V--VI; few efferent spindle-like neurons (40X20 micron) in layers V-VI. Stellate cells found in layers II-VI probably unite the pyramidal cells localized within one or several layers. Some of the stellate cells in layers II-III establish long horizontal connections within the field. Interneuronal connections are formed by axo-somatic and axo-dendritic terminals with the prevalence of the latter; dendro-dendritic and axo-axonic contacts were rarely observed.