[Age-specific features of the movement control system in young schoolchildren]. / Vozrastnye osobennosti sistemy upravleniia dvizheniiami u detei mladshego shkol'nogo vozrasta.

Analyzing spatial, temporary, and strength characteristics of movements in 7-10-year-old children by using a graphoanalytical method during the reverse exercise test has indicated that overstrain occurs in all units of the structures that ensure formation and implementation of a transitional process. There are increases in regulation errors by 33%, regulation time by 21.5%, system variability by 16%, regulation stability by 19%. The variability of the system is beyond three fluctuations, which is an indicator of full transition of the movement control system in unreliability and instability. The investigations have demonstrated that the reverse exercise procedure is adequate to age-related features of children and may be useful in studying different functional systems. The graphoanalytical method of quantitative assessment of the functional status of the locomotor apparatus is of rather informative value and can be used in the professional activities of a teacher and trainer for personal assessment of the movement control system in children of different age.

[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.

[Effect of stimulation of the hypothalamus on the rhythmogenic activity of the smooth musculature of the ureters and systemic arterial pressure]. / Vliianie razdrazheniia gipotalamusa na ritmogennuiu deiatel'nost' gladkoi muskulatury mochetochnikov i sistemnoe arterial'noe davlenie.

The influence of low- and high-frequency stimulation of anterior, tuberal and posterior hypothalamic areas on the spontaneous rhythmogenesis in the ureter smooth muscles and on arterial blood pressure, was studied in anesthetized cats. High-frequency stimulation of all hypothalamic areas induced pressor responses with activating effects on motor activity of the ureter. The changes in the ureter rhythmic activity were synchronous with those of systemic arterial blood pressure. The low-frequency stimulation induced both pressor and depressor responses in different proportion. The depressor responses were not accompanied by any changes of the ureter rhythmic activity. Possible mechanisms of reversal of vasomotor responses in stimulation of hypothalamus, organization of sympathico-activating and sympathoinhibitory mechanisms and hypothalamic regulation of rhythmogenic function of the ureter, 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.

[Effect of hypothalamic stimulation on the appearance of the early and delayed responses of the somato-sympathetic reflex]. / Vliianie razdrazheniia gipotalamusa na proiavlenie rannego i pozdnego otvetov somato-simpaticheskogo refleksa.

Stimulation of somatic nerves evoked in the cat L2--L3 white rami a late two--wave response. High frequency stimulation of the hypothalamus induced an increase of the blood pressure, facilitation of the first component and suppression of the second component of the late response. The components of the early response were insignificantly affected by the stimulation. The paired stimuli technique revealed interaction of descending and peripheral afferent excitation of sympathetic preganglionic neurons. The role of baroreceptor and hypothalamic excitation in spinal sympathetic mechanisms is discussed.

Do sympathetic preganglionic neurones have a recurrent inhibitory mechanism?

In anaesthetized and immobilized cats 32.5% of the intermediolateral sympathetic preganglionic neurones (B2-SPN) in T3, T8-9 and L2 spinal segments can be re-excited antidromically by repeated stimuli only at very long interstimulus intervals (16 ms and more) considerably exceeding the refractoriness of the somata and axons of these neurones. This was observed in the absence of any association with subnormality or other peculiarities B2-SPN axons. In this group of B2-SPNs with prolonged time interval between repeated antidromic discharges, orthodromic spikes effectively inhibited the generation of antidromic ones for a period which was substantially longer than the possible collision time. The preceding antidromic activation of a fraction of the B2-SPN segmental pool partly inhibited the orthodromic reactions of the others in this segmented elicited by stimulation of segmental afferent fibres or spinal descending pathways. These data definitely indicate that some of the B2-SPN group have a recurrent inhibitory mechanism.

[Discharges in the white rami communicantes evoked by stimulation of various sections of the hypothalamus]. / Razriady v belykh soedinitel'nykh vetochkakh, vyzvannye razdrazheniem raznykh otdelov gipotalamusa.

Electrical responses in L2--L3 white rami on stimulation of anterior and posterior hypothalamus were studied in anesthetized and immobilized cats. The stimulation evoked a complex response consisting of waves I, II, and III with mean latency 19.7 +/- 4.5 msec, 34.0 +/- 5.9 msec, 61.8 +/- 8.7 msec, and 20.5 +/- 6.8 msec, 30.;7 +/- msec, 66.0 +/- 14.9 msec for anterior and posterior hypothalamus respectively. In experiments with simultaneous recording of arterial pressure and hypothalamo-sympathetic discharges, after 10-sec period of tetanic (100/sec) stimulation of the hypothalamus, the early I and early II components were facilitated, while the late component of the hypothalamo-sympathetic discharge was depressed. The duration of this inhibition corresponded to the period of pressure reaction and, therefore, is of baroreceptor origin. Possible mechanisms of hypothalamic regulation of the activity of sympathetic preganglionic neurons are discussed.

[Recurrent inhibition of the sympathetic pregnaglionic neurons of the lateral horns of the spinal cord]. / Vozvratnoe tormozhenie simpaticheskikh pregnaglionarnykh neironov bokovykh rogov spinnogo mozga.

32.5% of the lateral horn sympathetic preganglionic neurons (B2-SPN) recorded in T3, T8-9 and L2 spinal segments of anaesthetized and immobilized cats were able to respond antidromically to repeated stimuli with time interval (16 ms and more) considerably exceeding the refractoriness of these neurons. This effect was not associated with axonal subnormality. A prolonged time interval between antidromic discharges correlated with the ability of orthodromic spikes to inhibit the generation of antidromic discharges throughout the same period which was substantially longer than the possible collision time. Preceding antidromic activation of a fraction of the described neurons partly inhibited the responses of other neurons in this segment elicited by stimulation of segmental nerves or spinal descending pathways. These data indicate that certain lateral horn sympathetic preganglionic neurons have a recurrent inhibitory mechanism.

Study of the early somatosympathetic reflex response.

Using anesthetized cats, we studied the early components of the somatosympathetic reflex in the white rami communicantes of segments T(3) and L(2) in response to stimulation of the corresponding segmental somatic nerves. The results show that the early somatosympathetic reflex is a complex and highly organized response consisting of three typical waves. The shortest latency wave of this reflex was investigated in detail and evidence of its monosynaptic nature was obtained. Calculations showed that the efferent part of this reflex component may be formed by sympathetic preganglionic neurons with axonal conduction velocities of about 10 m/sec or more.

Antidromic discharges of sympathetic preganglionic neurons located outside of the spinal cord lateral horns.

Responses arising in thin ventral rootlets and antidromic discharges of single sympathetic preganglionic neurons (SPNs) in T(3) and L(2) segments of the cat spinal cord were recorded simultaneously during stimulation of the white rami communicantes in the same segments. It was shown that in addition to the classical lateral horn SPN with B-axons (conduction velocities 3-10 m/sec) there are also ventral horn SPNs which have B-axons with faster conduction velocities (10-20 m/sec) and intermediate zone SPNs with C-axons (conduction velocities 0.98-1.7 m/sec).

[Polysynaptic components of the early somato-sympathetic reflex response in the lumbar white rami communicantes]. / Polisinapticheskie komponenty rannego somato-simpaticheskogo reflektornogo otveta v poiasnichnykh belykh soedinitel'nykh vetochkakh

The second and third components of early somatosympathetic relfex discharge were studied in anesthetized cats. Polysynaptic components of the early somatosympathetic and propriospinal somatosomatic discharges were compared. Evidence was found that these reflexes have both common and specialized interneurons in their central polysynaptic chains. It is suggested that the components of the early somatosympathetic reflex are formed by different types of sympathetic preganglionic neurons, namely the second component by neurons of the lateral horns and the third one--by neurons detected in the lateral part of intermediate zone (axonal velocity less than 1.5 m/s). A classification of sympathetic preganglionic neurons is presented.