[THE CARDIORESPIRATORY PLASTICITY IN CHILDREN DURING THE PROCEDURE OF PACED BREATHING].

The cardiorespiratory plasticity in healthy children 9-10 years old (n = 72) was studied during the procedure of paced breathing. The observations of a child after an informed consent taken from him, his parents and teachers were carried out by a psychologist, a physiologist and a doctor after the lessons. In a preliminary series 1 minute trials of pace breathing with various frequencies (22-5.5 times/minute) were used which showed a good endurance of slow breathing. Inthemain series a 3 minute baseline recording and 4-5 periods of 1.5 minute duration with a stepwise reduction of breathing rate of 12, 8, 7, 6 times/minute and in 10 children - 5.5 times/minute were registered. Computer-aided pacer set the durations of inspiration, expiration, pause. The main parameters of heart-rate variability (HRV) and corresponding FFT spectra were analyzed by ANOVA. In children a high cardiorespiratory plasticity of heart rhythm according to frequency of pace breathing is observed. During the stepwise reduction of breathing rate a quasilinear growth of HRV and peak power of FFT spectra of RR-intervals are registered, reaching the maximum level in a HF-band at 12 breaths/min and in LF-band at frequencies of 6-5.5 that are critical to the sustained volitional control of cardiorespiratory processing in children. At 6-5.5 breaths/min a growth of HF-band power of heart rhythm modulation is also registered.

[Analysis of cardiorespiratory coupling in athletes and non-athletes at paced rate of breathing].

The aims of the work were the study of cardiorespiratory coupling by method of paced breathing and the analysis of heart rate variability in men. Heart rhythm of 14 athletes and 12 non-athletes, 21 ± 1.4 years old, was registered in 3 minute sessions during spontaneous and paced breathing 14, 10, 9, 8, 7, 6, 5, 4 times/minute. The subjects were following breathing rate from a display. Initial heart rate being more slow in athletes (p < 0.05) was retained during episodes of controlled breathing. The power of FFT spectra peaks of RR-intervals was growing quasilinearly during reduction of breathing rate, reaching its peak value at 5-4 breaths/minute in athletes. More pronounced modulations of RR intervals were observed in HF spectral band (p < 0.05) of athletes breathing 14-10 times/minute compared to non-athletes. The power of LF band of the spectrum in athletes breathing 8-4 times/minute was 2 times higher: variability of RR-intervals "shrinked" accordingly to paced breathing rate. The dominant role in slow oscillations of heart rate manifested by paced respirations with involvement of vagus baroreflex afferentations of lungs and chest is hypothesized to be the consequence of breathing under attentional control.

[Plasticity of heart rate modulation of young adults during paced breathing with different frequencies].

The effect of paced breathing 10, 9, 8, 7, 6, 5, 4 times per minute with 160 and 90 s duration on the plasticity of slow modulations of heart rate was studied on 29 participants aged 21, both men and women. It was shown that the power spectrum of RR-intervals have dominant harmonics both in high- and low-frequency domains, peaking at 0.08-0.06 Hz for 160 s segments. Low-frequency peaks of the spectrum were growing in power linearly as a result of the graded slowing down of breathing rate. Frequency-dependent modulations of RR-intervals for a wide range of breathing frequencies confirm a substantial cardio-respiratory plasticity underlying cognitive and somatic processing.

[Low-frequency neuronal oscillations as operant processing of integrative mechanisms of conditioning and plasticity].

It was found that neuronal activity of the rabbit somatosensory cortex could be operantly conditioned according to the given algorithm of biofeedback control of nociceptive stimulation leading to rising or lowering of firing rate of multiunit activity, or to changes of range of units interspike intervals, or neuronal firing patterns for conditional stimulus, which become operants. Neuronal interactions of its population with feedback and systems of cardiovascular and pain regulation lead to appearance of wave patterns, combining elements to integrative activity by conditioning. Low-frequency oscillations of neuronal assemblies within range of 0.02-0.8 Hz act as operant processing in mechanisms of system plasticity and conditioning.

[Dynamic changes in the heart beat frequency of rabbits to auditory and nociceptive signals against the background of neuroleptic action]. / Dinamika izmenenii chastoty serdtsebienii krolika na zvukovoi i notsitseptivnyi signaly na fone deistviia neiroleptika.

Aminazine and haloperidol exerted different effects upon spontaneous heart rate and the reactivity of cardiovascular system in curarized rabbits during habituation to nociceptive and sound signals: aminazine (8-10 mg/kg) increased the heart rate by 8-12% and completely suppressed the reactivity, whereas haloperidol (0.5-1.7 mg/kg) decreased the heart rate by 5.0-8.5% and considerably enhanced the reactivity to sound and nociceptive signals, prolonging the habituation duration. The biphasic response of the rabbit heart rate reveals a working mechanism of the baroreflex control over emotionally significant and stressful effects.

[Potentiation of the chronotropic reaction of the rabbit heart during nociceptive stimulation]. / Potentsiatsiia khronotropnoi reaktsii serdtsa krolika pri notsitseptivnoi stimuliatsii.

Experiments with tricuran curarized rabbits have demonstrated that biphasic response that occurs during nociceptive limb stimulation (10--20 V) resulted in a short-term unmarked increase in the hear rate (HR) followed by a prolonged decline of the HR and then transforms to remarkable potentiation of the bradycardiac component upon rhythmic stimulation. The maximal potentiation develops within 15--40 s at a frequency of 2--01 Hz. This demonstrates a non-liner correlation between the potentiation onset and the frequency increase within the ranges mentioned. After stimulation for 40--130 s there take place a noticeable decrease in the heart rate response and destruction of rhythmic reaction observed at a lower frequency, namely the response decline (habituation). At a lower frequency (less than 0.1 Hz) the potentiation develops within several minutes, reaches maximum in 150--250 s with the wave-like potentiation following. Thus, upon rare rhythmic nociceptive stimulation HR potentiation has an appreciable long-term effect when repeated many times, and affects the conditioning.

[Analysis of the activity of neuronal populations in the brains of rabbits during adaptive self-regulation]. / Analiz aktivnosit neironnykh populiatsii golovnogo mozga krolika v protsesse adaptivnoi samoreguliatsii organizma.

The multiple unit (of 2 to 10 elements) activity of the somatosensory cortex was studied with the help of autospectral analysis in a rabbit learned with biofeedback technique from changes of the neuronal current discharge frequency. The background activity of neuronal pools is characterized by several basic profiles of frequency spectra. In most neuronal pools, after 4 to 12 min. of stimulation (below-threshold frequency is reinforced), the frequency of neuronal discharges is steadily enhanced, and the number of pain stimulations correspondingly diminishes by 30 to 50% for a few minutes or longer -- the result of learning. The appearance and increase in the autospectra of a relatively higher frequency component (0.35 to 0.6 c/s) during adaptive reorganizations reflects the influence of an effective feedback control; enhancement of the power of oscillations with a 0.05 to 0.07 c/s frequency testifies to a process of search by the system of the state extremum.