[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.

[The role of various parts of the amygdaloid complex in the regulation of activity of respiratory neurons]. / Uchastie razlichnykh struktur mindalevidnogo kompleksa v reguliatsii aktivnosti bul'barnykh dykhatel'nykh neironov.

In microelectrophysiological investigations influences of different nuclear regions of the amygdaloid complex on the spike activity of the functionally identified single respiratory neurons of the medulla oblongata were studied in anesthetized cats. It was established a qualitative different character of the changes of unit activity of the medullary respiratory neurons in case of stimulation of phylogenetically old corticomedial or new basolateral nuclear groups of the amygdala. It was shown higher reactivity of the investigated neurons to stimulation of the corticomedial nuclei than basolateral. The influences of the corticomedial nuclear groups on the bulbar inspiratory and expiratory neurons were facilitatory as well as inhibitory with prevailing excitatory effects. It was found that influences of the phylogenetically new neoamygdaloid structures of basolateral region on spike activity of the bulbar respiratory neurons differ accordingly to their topographical differentiation. Mechanisms of amygdaloid control of activity of the medullary respiratory neurons are discussed.

[The neuronal organization of the amygdala-visceral reflex arch]. / Neironnaia organizatsiia amigdalo-vistseral'noi reflektornoi dugi.

The paper summarizes the histomorphic, histochemical, autoradiographic, immune-histochemical and electrophysiological data on the structural-functional organization of the amygdalar complexes. While discussing the problem of neuron organization of the afferent and efferent groups in the amygdala-visceral arch the authors present their data of microelectrophysiological studies of the specific amygdala neuron reactions in response to stimulation of the vagus, ventric, and sciatic nerves, and of the second somatic sensor cortex zone. It was observed that interoceptive impulsation reaching the polysensor neurons of the central, corticomedial, and basolateral groups of the amygdala complex nuclei have no significant qualitative differences. A series of experiments demonstrated that the polysensor convergent amygdala neurons are also polyeffectoral. Comparative studies of the sympathetic discharges in the white connecting branches produced by stimulation of the above nuclear amygdala groups, confirmed absence of a clear topographic localization of the sympatho-activating structures within an amygdala. Comparative exploration of the parasympathetic discharges in the pelvis nerve discovered a discharge of complex configuration in response to simulation of the pelvis nerve nuclei. There was no notable topographic localization of the amygdala parasympathoactivating structures. The system's arterial pressure was studied in response to stimulation of various amygdala structures. Low-frequency stimulation (5 Hertz) of all amygdala structures produces depressor reactions, high-frequency stimulation (100 Hertz) produces pressor reactions. Microelectrophysiological data are provided on the specific reactions of the inspiration and expiration neurons of the bulbar respiratory centre under frequency stimulation of various amygdala structures. The authors have concluded that the bulbar-spinal mechanisms regulating the vegetative functions are implemented by polysensoral-polyeffectoral integrative amygdala neurons of the convergent-divergent type. Consequently, there are no separate populations of the sympatho-activating and parasympathoactivation neurons and of the selective structures regulating the respiratory and the cardiovascular functions.

An investigation of certain physiological mechanisms of the neurohumoral regulation of vascular tone.

The neuronal organization of the hypothalamobulbar system of regulation of vascular tone was studied in experiments on cats anesthetized with chloralose and nembutal and immobilized by dithylin [suxamethonium iodide]. It was established that the descending influence of the posterior, tuberal, and paraventricular structures of the hypothalamus on the activity of antidromically identified sympathicoactive reticulospinal neurons of the ventrolateral region of the medulla oblongata is realized by mono-, oligo-, and polysynaptic mechanisms. It was shown in a series of experiments carried out in rats that animals subjected to chemical desympathization, by contrast with the controls, do not develop chronic neurogenic hypertension during a six-week stressor influence on higher nervous activity. The central and peripheral neurohumoral mechanisms of the regulation of vascular tone are discussed.

[The physiological mechanisms of the neurohumoral regulation of vascular tonus]. / Issledovanie nekotorykh fiziologicheskikh mekhanizmov neirogumoral'noi reguliatsii sosudistogo tonusa.

Neuronal organisation of hypothalamo-bulbar mechanisms of regulation of vascular tonus was studied in anesthetised and immobilised cats. The descending influence of posterior, tuberal and anterior structures of the hypothalamus on the activity of antidromically identified sympatho-activating reticulospinal neurons of the ventrolateral region of medulla oblongata is realised by mono-, oligo- and polysynaptic mechanisms. Chronic neurogenic hypertension was induced in rats by overloading the higher nervous activity. Arterial hypertension did not develop in chemically desympathized cats. Central and peripheral neurohumoral mechanisms of vascular tonus regulation are discussed.

[The effect of cholino- and adrenoblockers on limbic-sympathetic evoked potentials]. / Issledovanie vliianiia kholino- i adrenoblokatorov na limbiko-simpaticheskie vyzvannye potentsialy.

Effects of i.v. administration of cholino- and adrenergic blocking agents on limbic-sympathetic discharges of L2-L3 white rami, evoked by stimulation of the anterior, visceral area of the limbic cortex and on arterial blood pressure were studied in anesthetized cats. M- and N-cholinoreceptor blocking agents atropine and ganglerone do not induce any apparent changes in limbic-sympathetic discharge and the blood pressure level. Beta-adrenoreceptor blocking agent propranolol evoked a small fall of the blood pressure with no apparent changes of limbic-sympathetic discharges. Alpha-adrenoreceptor blocking agent phenotolamine evoked obvious drop of the blood pressure and, in two out of eight experiments, a marked increase of the amplitude of limbic-sympathetic evoked discharges. Neurochemical regulatory mechanism of limbic-spinal sympathetic activity are discussed.

[Comparative study of the discharges of sympathetic and parasympathetic nerves during stimulation of the visceral field of the limbic cortex]. / Sravnitel'noe issledovanie razriadov simpaticheskikh i parasimpaticheskikh nervov pri razdrazhenii vistseral'nogo polia limbicheskoi kory.

Comparative characteristics of parasympathetic responses in pelvic nerve and sympathetic responses in lumbar white communicating rami to stimulation of dorsal and ventral parts of anterior, visceral area of limbic cortex were studied in anesthetized and immobilized cats. Single shocks or short trains of stimuli of the area 25 in limbic cortex evoked a complex response in pelvic nerve, consisting mostly of three waves: the late waves II and III of the parasympathetic discharge with a mean latency of 63.3 and 180.4 msec, and a mean magnitude of 11.0 and 16.7 microV, resp. A short latency component was rarely observed and its latency was about 15.9 msec. The EPs in pelvic nerve and white rami had the lowest threshold in stimulation of the ventral part of area 25. Comparative study of the excitability-recovery properties of cingulo-parasympathetic and cingulo-sympathetic responses revealed a long-lasting inhibition of the test responses for 2000 and 900 msec, resp.

[Comparative study of mechanisms of change in vasomotor sympathetic activity upon stimulation of different structures of the limbic cortex and hypothalamus]. / Sravnitel'noe issledovanie mekhanizmov izmeneniia vazomotornoi simpaticheskoi aktivnosti pri razdrazhenii razlichnykh struktur limbicheskoi kory i gipotalamusa.

Responses of arterial blood pressure to low- and high-frequency stimulation of different structures of the limbic cortex and hypothalamus were studied in anesthetized and immobilized cats. The low-frequency (5 Hz) stimulation induced depressor reactions, the high-frequency (100 Hz) one-pressor responses. Both kinds of stimulation in the dorsal level of area 25 and of area 23 of the limbic cortex and of the anterior hypothalamus induced similar depressor responses, whereas the hypothalamic structures in the posterolateral region induced only pressor responses. The role of poly-effectory, sympatho-inhibitory and sympatho-activating neurons responsible for the observed three patterns of the blood pressure changes in low- and high-frequency stimulation of limbic cortex and hypothalamus, is discussed.

[Discharges in the white rami communicantes evoked by stimulation of different fields of the limbic system]. / Razriady v belykh soedinitel'nykh vetochkakh, vyzvannye razdrazheniem razlichnykh polei limbicheskoi kori.

Electrical responses to stimulation of different areas of the cingulate gyrus were studied in L2-L3 white rami in anesthetized and immobilized cats. The stimulation evoked a sympathetic discharge mostly consisting of a wave with a mean latency of 71.2 +/- 2.3 ms. In a few cases, the main wave was preceded by a short-latency component. Thresholds for eliciting sympathetic discharges were lower in case of stimulation of the ventral region of area 25 in comparison to those of the dorsal region of the same area. A comparative study showed that the lowest were the thresholds of hypothalamic evoked discharges, somewhat higher were the thresholds of amygdala stimulation and the highest were those of the cingulate cortex evoked discharges. In experiments with simultaneous recording of arterial pressure and cingulo-sympathetic discharges, after 10-sec period of tetanic (100/sec) stimulation of the limbic cortex, the early components were facilitated while the late component of the cingulo-sympathetic discharges was depressed. The duration of this inhibition corresponded to the period of pressure reaction and, therefore, was of a baroreceptor origin. Possible mechanisms of cingulate cortex regulation of the activity of sympathetic preganglionic neurons, are discussed.

[Characteristics of the response of the white rami communicantes to stimulation of different sections of the amygdaloid body]. / Kharakteristika otvetov belykh soedinitel'nykh vetochek, vyzvannykh razdrazheniem razlichnykh otdelov mindalevidnogo kompleska.

Electrical responses in L2-L3 white rami to stimulation of cortico-medial, baso-lateral and central amygdaloid nuclei were studied in anesthetized and immobilized cats. The stimulation evoked a similar pattern of sympathetic discharge mostly consisting of a wave with a mean latency of 69.04 +/- 1.31 ms. No strict topographical location of sympatho-activating structures was found in different areas of the amygdala. In simultaneous recording of arterial BP and amygdalo-sympathetic discharges, 10-sec period of tetanic (100/sec) stimulation of the amygdalo led to a short-latency component facilitation or appearance, the late component of the amygdalo-sympathetic discharge being depressed. The duration of the latter inhibition corresponded to the period of the BP reaction and therefore was of a baroreceptor origin. Possible mechanisms of amygdaloid regulation of the activity of sympathetic preganglionic neurons are discussed.

[Mechanism of change in vasomotor sympathetic activity after stimulation of various amygdaloid structures]. / Mekhanizmy izmenenii vazomotornoi simpaticheskoi aktivnosti pri razdrazhenii razlichnykh struktur amigdaly.

The influence of low- and high-frequency stimulation of cortico-medial, baso-lateral and central nuclei of the amygdala was studied in anesthetized cats by means of recording arterial blood pressure and electrical activity of the amygdala. The induced vasomotor effects were compared with the effect of hypothalamic stimulation. The low-frequency stimulation of all amygdaloid nuclei induced depressor reactions, while the high-frequency stimulation of the same areas induced an obvious pressure response. The pressure effect, however, was less obvious and of shorter duration as compared with the hypothalamic pressure responses. No correlation was found between electrical seizure discharges and blood pressure reactions to the low- and high-frequency stimulation. Mechanisms of reversal of vasomotor responses to stimulation of amygdala, diffuse organization of amygdaloid sympathoactivating mechanisms, and amygdaloid mechanisms of vasomotor regulation, are discussed.

[Responses of pericruciate cortex neurons to stimulation of the hypothalamus and reticular formation]. / Reaktsii neironov perikrutsiatnoi oblasti kory na razdrazhenie gipotalamusa i retikuliarnoi formatsii.

Neurons of the pericruciate cortex revealed a high degree of reactivity to stimulation of posterior hypothalamus (HP) and mesencephalic reticular formation (RF)--94 and 88% resp., and a marked convergence of upward discharges from HP and RF (73.5%) in anesthetized and immobilized cats. Latency and unit responses (2.4--4.0 msec) suggested a monosynaptic input from the two subcortical structures. Out of the corticofugal neurons activated antidromically, 27% were of the "divergent" type with collaterals in both the HP and RF and, therefore, reacting antidromically to stimulation of these structures. A predominance of cortical antidromic responses to stimulation of HP suggested a greater corticofugal influence on hypothalamic rather than on reticular neurons (84% and 42.3% resp.). Mean latency of antidromic reaction of cortico--hypothalamic neurons was 2.4 +/- 0.2 msec (0.8--6.0 msec), of cortico--reticular neurons--3.2 +/- 0.3 msec (1.0--6.0 msec). The conduction velocity (12.5 m/sec) was the same for both the HP and RF. Characteristics of neuronal organization of hypothalamo--cortical and reticulo--cortical systems of integration are discussed.

[Comparative characteristics of hypothalamo-cortical and reticulo-cortical evoked potentials]. / Sravnitel'naia kharakteristika gipotalamo-korkovykh i retikulo-korkovykh vyzvannykh potentsialov.

In anesthetized and immobilized cats, single shock stimulation of the postero-lateral hypothalamus (Hp) and mesencephalic RF elicited positive-negative evoked potentials in gyrus sigm. anterior (GSA) with a latency of 0.8--2.5 msec and 1.0--3.0 msec for hypothalamo-cortical (HC) and reticulo-cortical (RC) EPs respectively. In gyr. suprasylv. ant. (GSSA) HC and RC EPS with initial negative wave were recorded with a latency of 1.0--3.5 and 0.5--4.0 msec resp. The HC and RC EPs followed frequency of stimulation up to 40/sec and were capable of obvious postetanic potentiation. Paired stimuli revealed that the main positive wave of HC and RC EPs appeared in GSA at an interval of 5--10 msec. In GSSA the surface negative potential appeared at an interval of 10 msec. Full recovery occurred at an interval of 150--200 msec. A biphasic change of excitability of cortical neurons occurred in response to conditioning stimuli. Comparative study of recovery cycles of HC EP to paired stimuli of Hp or mesencephalic RF in one case and of conditioning stimulation of the RF and testing stimulation of Hp in other, suggest predominance of "convergent" cortical neurons with polysensory input from Hp and RF. The characteristics of functional organization of hypothalamo-cortical system of integration are discussed.