[Comparative study of effects of cortical nucleus of amygdala and pyriform cortex on activity of bulbar respiratory neurons in cats].

Comparative microelectrophysiological study of character and peculiarities of effects of the cortical nucleus of amygdala and of the periamygdalar area of pyriform cortex on impulse activity was performed on the same single functionally identified respiratory medullar neurons. A high reactivity of bulbar respiratory neurons on stimulation is established in both studied limbic structures. There is established the qualitatively different character of their response reactions at stimulation of the cortical amygdala nucleus and the periamygdalar cortex. The cortical amygdala nucleus has been shown to produce on the activity of medullar respiratory neurons both facilitating and inhibitory action with predominance of the activating one (without topographical orderliness). The effect of periamygdalar cortex at stimulation of various parts was characterized by topographic differentiation. The suppressing reactions of neurons in the majority of cases were recorded at stimulation of the rostral area of periamygdalar cortex, whereas the excitatory reactions--at stimulation of its caudal part. Functional organization of respiratory control of the studied limbic system structures is discussed.

[The neuronal organization of the limbic (cingulo-)-visceral reflex arc]. / Neironnaia organizatsiia limbiko (tsingulo-)-vistseral'noi reflektornoi dugi.

The paper summarizes new electrophysiological data concerning the structural-functional organization of the limbic cortex and role of the rostral limbic region of visceral functions. Here are presented the results of a series of electrophysiological investigation of the focus of localization in the supracallosal (area 24) and infracallosal (area 25) part of the anterior cingulate gyrus of evoked potentials of maximal amplitude and minimal latent period to stimulation of pelvic, splanchnic and sciatic nerves. It was shown that evoked potentials of maximal amplitude and minimal latent periods to stimulation of viscero-somatic nerves are recorded in the supragenual area 24 in comparison with the infragenual area 25 of the anterior limbic cortex. In a series of microelectrophysiological studies of reactions of neurons of area 24 and 25 it was established that the reactivity of neurons of area 24 is higher than that of area 25. All these data indicate to the leading role of area 24 in reception and treatment of viscero-somatic afferent signals. In series of experiments it was shown that the focus of exciting neurons, forming the descending singular-autonomic discharge is localized in the infragenual area 25 of anterior limbic cortex. In a study of the comparative characteristics of sympathetic responses in lumbar white communicating rami and parasympathetic responses in pelvic nerve it was shown that evoked potentials in pelvic nerve and white rami had the lowest threshold and shorter latency in case of stimulation of area 25. Study of characteristics of influence of dorsal (area 24) and ventral (area 25) regions of rostral limbic cortex on bioelectrical activity of two postganglionic sympathetic nerves-inferior cardiac and vertebral branches of stellate ganglion, innervating coronary vessels and vessels of anterior extremities correspondingly, showed that stimulation of ventral area 25 evoked increase of electrical activity of the two sympathetic nerves and reliable increase of systemic arterial pressure, while stimulation of dorsal area 24 evoked decrease of tonic activity of the two sympathetic nerves and reliable decrease of systemic arterial pressure. In the paper are presented also the results of microelectrophysiological investigation of peculiarities of reactions of inspiratory and expiratory neurons of bulbar respiratory center to high frequency stimulation of area 24 and 25--in case of stimulation of dorsal area 24 the prevailing effect is suppression of spike activity of neurons, of stimulation of ventral, infragenual area 25 the prevailing influence is excitatory. In another series of microelectrophysiological experiments it was shown downward blocking inhibitory influence of dorsal supragenual area 24 of anterior limbic cortex on activity of vagal viscerosensory neurons of bulbar solitary tract nucleus. It is concluded that the strictly connected one another areas 24 and 25 of limbic cortex are functionally differentiated: the infra-limbic cortex is mainly a viscero-motor cortex, while the prelimbic area 24 plays a leading role in reception and treatment of viscero-somatic afferent information.

[Parasympathetic discharges of the pelvic nerve during stimulation of different hypothalamic structures]. / Parasimpaticheskie razriady tazovogo nerva pri razdrazhenii razlichnykh struktur gipotalamusa.

The characteristics of evoked responses in pelvic nerve elicited with electrical stimulation of posterior, tuberal, anterior hypothalamus and preoptic area were studied in anesthetized and immobilized cats. The complex response in pelvic nerve consisted of waves I, II, III with latencies from 13 to 28, 52 to 96, 113 to 256 msec, resp. The evoked responses of lowest thresholds and shortest latencies were obtained from the posterior hypothalamus. These data suggest that hypothalamic parasympathoactivating neurons are localized mostly in the posterior hypothalamus. After high frequency (100/sec, 10-sec. period) stimulation of posterior and anterior hypothalamus which produced blood pressure increase, the mean component of pelvic discharge--wave III was depressed during the whole period of the pressure reaction, the inhibition being of baroreflex origin. Early components of the discharges after tetanic stimulation of hypothalamus were facilitated. Paired stimulation of the hypothalamus demonstrated that nearly 2.5 sec were required for complete recovery of the evoked test-responses in pelvic nerve.

[Comparative study of sympathetic and parasympathetic discharges in the autonomic nerves during stimulation of different structures of the cat hypothalamus]. / Sravnitel'noe issledovanie simpaticheskikh i parasimpaticheskikh razriadov v vegetativnykh nervakh pri razdrazhenii razlichnykh struktur gipotalamusa koshki.

Simultaneous recordings of hypothalamo-parasympathetic and hypothalamo-sympathetic evoked discharges in anesthetized cats demonstrated that both parasympathetic discharges in the pelvic nerve and sympathetic discharges in the splanchnic nerve of the lowest threshold and shortest latency could be obtained from stimulation of the posterior hypothalamus. The focus of the maximal neuronal activated elicited by stimulation of afferent fibres of visceral nerves and the focus evoking maximal efferent reactions of parasympathetic and sympathetic nerves were located in the same region of the postero-lateral hypothalamus. It is supposed (as a working hypothesis) that convergent polysensory neurons of the hypothalamus are also polyeffector divergent elements of the hypothalamo-visceral reflex system.

[Reactions of hypothalamic neurons to stimulation of the pelvic and sciatic nerves]. / Reaktsii neironov gipotalamusa na razdrazhenie tazovogo i sedalishchnogo nervov.

Unit activity of posterior, tuberal and anterior parts of the hypothalamus was studied during stimulation of the pelvic nerve in anesthetized and immobilized cats. Comparative analysis showed that neurons of the posterior hypothalamus were more responsive (89.6%) and had a shorter mean latency (33.3 +/- 2.4 msec) than neurons of more rostral parts of the hypothalamus. The focus of maximal pelvic-induced unit activity seems to be located in the posterior hypothalamus. The unit responses of the posterior hypothalamus evoked by pelvic nerve stimulation had long recovery cycles and were suppressed at low frequencies of stimulation. These findings suggest a polysynaptic organization of pelvic afferent projection in the hypothalamus. A high degree of convergence of the visceral and somatic afferent signals onto single neurons was found during stimulation of pelvic and sciatic nerves. The functional role of neurons of integrative types is discussed.

[Evoked hypothalamic potentials from the pelvic nerve]. / Vyzvannye potentsialy gipotalamusa pri razdrazhenii tazovogo nerva.

Comparative electrophysiological analysis of EPs in the posterior, tuberal and anterior hypothalamus to electrical stimulation of the pelvic nerve was performed in anesthetized and immobilized cats. The focus of maximal activity was revealed in the postero-lateral hypothalamus. "Visceral" responses of the hypothalamus evoked by the pelvic nerve stimulation had a long recovery cycle and were suppressed at a low-frequency stimulation. These findings suggest a poly-synaptic organization of the projection of pelvic afferent systems in the hypothalamus.

[Projections of the visceral and somatic afferent systems to identified neurons of the supraoptic nucleus]. / Issledovanie proektsii vistseral'nykh i somaticheskikh afferentnykh sistem k identifitsirovannym neironam supraopticheskogo iadra.

Antidromic identification of the hypothalamic supraoptic nucleus' neurosecretory cells in cats in the course of stimulation of the posterior hypophysis aided to study the possibility and degree of modulation of the unit activity by ascending visceral and somatic afferent signals during stimulation of the splanchnic and sciatic nerves. the data obtained revealed that the major part of the neurosecretory neurons cannot be activated by means of the afferent signals. The projections of visceral and somatic afferent systems represented by the splanchnic and sciatic nerves, spread over to the nonroendocrinal cells of the hypothalamic supraoptic nucleus. The functional role of peripheral afferents in modulation of the hypothalamic neuroendocrinal neurons activity, is discussed.