[Septal nuclei in the regulation of vago-sensitive neurons activity of the solitary nucleus in cats]. / Rol' septal'nykh iader v reguliatsii aktivnosti vagosensitivnykh neironov iadra solitarnogo trakta u koshek.

The descending influences of the septal nuclei (lateral nucleus--LSN and bed nucleus stria terminalis--BNST) on activity of viscero-sensory neurons of the nucleus of tractus solitarius (NTS) identified by stimulation of cervical part of the n. vagus were investigated in the cat anaesthetised by chloraloze-nembutal combination. It was found that out of 70 units recorded in the NTS area 50 were identified as those of primary and secondary input vagal neurons. Influence of single, paired and frequency stimulation on the septal structures was studied on these neurons. It was revealed that 30% (15 un) reacted by phase-specific response to the single stimulation of the septal nuclei. The latent period of initial excitation was in the range 5-25 ms. During the paired stimulation these neurons were not able to react to the second stimulus for the equal 10-300 ms. It was revealed that 34% (17 un) of the identified vagal neurons reacted by a tonic change of their spontaneous activity. The increase of frequency stimulation to 20 Hz evoked different changes of the rhythmical activity of the vagal neurons (increase, diminishing or inhibition). The study of interaction between central and peripheral signals in the solitary neurons induced blocking influence of descending septal discharge on the vagal test response. It is possible that the septal downward impulses reach the vago-sensitive solitary neurons indirectly through other structures of the limbic brain (amygdala, hypothalamus) and participate in modulation of the spontaneous activity of these neurons.

[Neuron mechanisms of the regulation of bulbar vagosolitary activity by structures of basolateral amygdala nuclei in cats]. / Neironnaia organizatsiia mekhanizmov reguliatsii aktivnosti bul'barnykh vagosolitarnykh neironov strukturami bazolateral'nykh iader amigdaly u koshek.

Neuronal reactivity to single stimuli applied to both the peripheral nerves and the cortex, was the same in the cat solitary tract nucleus. The 1-20 Hz stimulation frequency rendered the reactivity either tonic in character or with reduced firing rate. A high degree of convergence (80.2%) on baso-lateral nuclei neurons was established, as well as a significant cortico-fugal effect (71%) on the viscero-sensory units of these nuclei. Single shocks and tetanic stimulation of the baso-lateral amygdala evoked mostly phasic responses of the primary as well as secondary vagal neurons. Feed-back mechanisms of the amygdaloid control of the bulbar viscero-sensory units are discussed.

[The reactions of the viscerosensory neurons of the nucleus solitarius to stimulation of the posterior and anterior hypothalamus]. / Reaktsii vistserosensornykh neironov iadra solitarnogo trakta na razdrazhenie zadnego i perednego gipotalamusa.

The "vagal" neurons of the solitary tract nucleus responded to stimulation of anterior and posterior hypothalamus in 78.7 and 27.6 per cent, resp., the responses being mainly of the activation type. The descending effect from the hypothalamus involved primary as well as secondary "vagal" neurons. The responses were of mono-, oligo- and polysynaptic nature.

[Neuronal reactions of the ventromedial hypothalamus to stimulation of gastric mechanoreceptors and to the intra-arterial administration of glucose and sodium chloride]. / Reaktsii neironov ventro-medial'nogo gipotalamusa na razdrazhenie mekhanoretseptorov zheludka i na vnutriarterial'noe vvedenie gliukozy i khloristogo natriia.

In anesthetized and immobilized cats, intact and with cut splanchnic nerves ("vagal" animals) of vagal nerves ("splanchnic" animals), high degree of responsiveness of hypothalamic neurons, with prevailing excitatory reactions, was found. The responses were obtained mainly to stimulation of gastric adapting mechanoreceptors. Information from the latters reaches the hypothalamic neurons through splanchnic and vagal afferents. Some hypothalamic mechanosensitive neurons were shown to be gluco- and osmosensitive and thereupon able to integrate both the neural and the humoral informations. The functional role of vagal and splanchnic mechanoreceptors of the stomach in activation of hypothalamic units and the "converging ability" of "visceral" neurons of the ventromedial hypothalamic feeding center, is discussed.

[Responses of different hypothalamic structures to stimulation of the viscero-caudal region of the nucleus of a the solitary tract of the medulla oblongata]. / Reaktsii neironov razlichnykh struktur gipotalamusa na razdrazhenie vistsero-kaudal'noi oblasti iadra odinochnogo puchka prodolgovatogo mozga.

Responses of single units of anterior, ventromedial, lateral and posterior hypothalamus to stimulation of the caudal viscero-receptive region of nucleus tractus solitarius were recorded in anesthetized and immobilized cats. The patterns of the responses were mainly excitatory in all structures under study. The highest degree of reactivity was found for units in the lateral and posterior hypothalamus. According to the latency of the evoked discharges three types of responses were revealed: short (6-12 msec), middle (13-22 msec) and long-latency (22-60 msec) responses. At relatively low frequencies of stimulation the reproducibility was rather poor. Possible projections from nucleus tractus solitarius to the hypothalamus are discussed.

[Development of the hypothalamic-cortical interrelations in the ontogeny of the cat]. / Izuchenie razvitiia gipotalamo-korkovykh vzaimootnoshenii v ontogeneze koshki.

Under chloralose narcosis, employing the evoked potentials method, studies have been made on the projection of the posterior hypothalamus to the frontal cortex in 1-30 days old kittens. The animals were divided into 3 age groups: 1-9, 10-19 and 20-30 days. Studies of the EPs in different points of pericruciate zone showed that these potentials are observed in all the investigated points from the first days of postnatal life. The latent period of responses in the youngest animals varied from 40 to 80 ms, exhibiting insignificant fluctuations depending on the cortical zone investigated. From the very beginning of postnatal life, in the same cortical zone the EPs may be observed in response to stimulation of the ischiadic nerve as well. In older animals, the latent period of the EPs decreases in all the points, the decrease being most significant near the crucial fissure. To the 30th day of postnatal life, the EPs in this zone with respect to their latency and configuration became quite similar to those in adult animals. In the third age period, the latency varies from 6 to 10 ms in the focus of maximum activity; with the removal of the recording electrode from this zone the latent period of the hypothalamo-cortical responses increases up to 30-40 ms. Overlapping of the EPs in response to central and peripheral stimulation was observed at all age periods.

[Response of hypothalamic neurons to different groups of afferent fibers of the subdiaphragmatic vagus nerve]. / Reaktsii neironov gipotalamusa na razdrazhenie razlichnykh grupp afferentnykh volokon poddiafragmal'nogo bluzhdaiushchego nerva.

Responses of single units of posterior, anterior, ventromedial and lateral hypothalamus to stimulation of abdominal trunk of the vagus nerve were recorded in anesthetized cats simultaneously with the action potentials of the cervical region of the vagus nerve. 28.1% of the neurons responded to the stimulation, the pattern of responses being mainly excitatory. Vagal stimulation proved to be more effective for units of the lateral hypothalamus, 47.1% of the excitatory reactions followed stimulation of A gamma delta--B afferents and 40.4%--stimulation of C afferents of the vagus. Topical organization of the projection of these groups of visceral afferents to different regions of the hypothalamus was partially revealed. Responses of some A gamma sigma--B and C neurons to stimulation of vagus and sciatic nerves suggest convergence of visceral and somatic afferents to the "convergence" types of neurons. Some A gamma delta--B and C units, chiefly in the ventromedial hypothalamus, responded only to stimulation of visceral vagal afferents. The sensory properties of "visceral" neurons of the hypothalamus are discussed.

[Convergence of visceral afferent impulsation on hypothalamic neurons following stimulation of the vagus and splanchnic nerves]. / Konvergentsiia vistseral'noi afferentnoi impul'satsii na neironakh gipotalamusa pri razdrazhenii bluzhdaiushchego i chrevnogo nervov

Responses of single hypothalamic units to stimulation of the vagal, splanchnic and sciatic nerves and to photic stimulation were studied in anaesthetized, curarized cats. Most of the reactive neurons of the posterior and anterior hypothalamus responded to stimulation of vagus and splanchnicus. The pattern of responses of these polysensory units reactive in most cases to sciatic nerve and (or) photic stimulation too, were mainly unidirectional, nonreciprocal and excitatory in case of stimulation of visceral afferents of parasympathetic and sympathetic nerves. Absence of reciprocal responses to stimulation of "antagonistic" autonomic nerves and predominance of "convergence" units with polysensory inputs suggest that the electrical reaction of most of posterior as well as anterior hypothalamic neurons are of nonspecific "reticular" type.

[Response of neurons of the anterior and posterior regions of the hypothalamus to stimulation of the vagus and sciatic nerves and photic stimulation]. / Reaktsiia neironov perednei i zadnei oblastei gipotalamusa na razdrazhenie bluzhdaiushchego i sedalishchnogo nervov i svetovuiu stimuliatsiiu

Evoked activity of single units in anterior and posterior hypothalamus to vagal, sciatic nerves, and photic stimulation was studied in anesthetized and immobilized cats. The responsiveness of neurons of the posterior hypothalamus was 66, 77 and 37% to vagal, sciatic nerves and photic stimulation, respectively, and of the anterior hypothalamus -- 47, 62 and 48%. Vagal stimulation was found to be the more effective for units of the posterior hypothalamus. Responses of units to a flash prevailed in the anterior hypothalamus. 78% of convergence of viscero-somatic afferentation on neurons of the posterior hypothalamus and 62% -- on anterior hypothalamic neurons, were revealed. The responses to all kinds of afferent stimuli were phasic and of excitatory character. Possible role and mechanisms of vagal interoceptive activation of hypothalamic units are discussed.

[Background and evoked activity of hypothalamic neurons during development in cats]. / Fonovaia i vyzvannaia aktivnost' neironov gipotalamusa v protsesse razvitiia u kotiat

In acute experiments on anaesthetized kittens, studies have been made on the background and the evoked activity of hypothalamic neurons elicited by sensory stimuli. It was shown that already from the 2nd day of postnatal life, it is possible to observe the background impulse activity of the neurons in the posterior hypothalamus. The evoked reactions to stimulation of the sciatic nerve were recorded at the 4-5th day of postnatal life. At early stages of ontogenesis, both phasic and tonic types of neuronal reactions are presented in the hypothalamus, the former being more frequent. To the end of the 3rd week, neuronal reactions in the hypothalamus do not reach definitive pattern.