CONDITIONED REFLEX MECHANISMS OF ADAPTATION TO ADDITIONAL BREATHING RESISTANCE

The problem of adaptation to additional breathing resistance has recently become more urgent due to the growth of bronchopulmonary diseases. Therefore, there is a natural interest in non-drug strategies compensating resistive breathing in humans. The aim of the study was to assess conditioned reflex changes in the functional state of the subjects under additional breathing resistance. Materials and Methods. The work was carried out on 55 practically healthy subjects of both sexes, aged 18–36. Additional breathing resistance was modeled by inspiratory resistive loads of 40, 60, 70, and 80 % of the maximum intraoral pressure. The conditioned respiratory reflex to resistive respiratory load was developed as a short-delayed conditioned signal with a 30-second period of isolated action. The authors examined behavioral, vegetative, gas and energy indicators of the organism before and after the formation of a conditioned reflex. Results. It was observed that conditioned reflex shifts of physiological parameters in the process of adaptation to additional breathing resistance differ significantly from the corresponding unconditioned reflex changes both in nature and in intensity. Conditioned reflex mechanisms reduce the intensity of shifts in the motor component of the external respiration system, which, apparently, is the main reason to decrease the aversive behavior. Conclusion. Behavioral changes after the formation of a conditioned respiratory reflex to additional respiratory resistance are characterized by a decrease in aversive behavior patterns. The conditioned reflex realization of increasing resistive loads is expressed in a lower physiological cost of adaptation to additional respiratory resistance relative to the unconditioned reflex type of realization. Keywords: adaptation, conditioned respiratory reflex, additional breathing resistance. Проблема приспособления к дополнительному респираторному сопротивлению в последнее время становится все более актуальной в связи с ростом бронхолегочных заболеваний. Поэтому естественен интерес к нелекарственным механизмам компенсации резистивного дыхания человека. Целью исследования являлась оценка условно-рефлекторных изменений функционального состояния испытуемых в условиях дополнительного респираторного сопротивления. Материалы и методы. Работа проведена на 55 практически здоровых испытуемых обоего пола в возрасте от 18 до 36 лет. Дополнительное респираторное сопротивление моделировалось инспираторными резистивными нагрузками величиной 40, 60, 70 и 80 % от максимального внутриротового давления. Условный дыхательный рефлекс на резистивные дыхательные нагрузки вырабатывался по типу короткоотставленного с периодом изолированного действия условного сигнала 30 с. Исследовались поведенческие, вегетативные, газовые и энергетические показатели организма до и после формирования условного рефлекса. Результаты. Показано, что условно-рефлекторные сдвиги физиологических показателей в процессе приспособления к дополнительному респираторному сопротивлению существенно отличаются от соответствующих безусловно-рефлекторных изменений как по характеру, так и по интенсивности. Условно-рефлекторные механизмы уменьшают интенсивность сдвигов моторного компонента системы внешнего дыхания, что, по-видимому, является основной причиной снижения вероятности появления аверсивного поведения. Выводы. Поведенческие изменения после формирования условного дыхательного рефлекса на дополнительное респираторное сопротивление характеризуются снижением вероятности появления аверсивных форм поведения. Условно-рефлекторная реализация возрастающих по интенсивности резистивных нагрузок выражается в меньшей физиологической стоимости приспособления к дополнительному респираторному сопротивлению относительно безусловно-рефлекторного типа реализации. Ключевые слова: приспособление, условный дыхательный рефлекс, дополнительное респираторное сопротивление.

Pathophysiological mechanisms of resistive breathing

AIM: This study aimed to explore the pathophysiological mechanisms of resistive breathing by using a model of a conditioned respiratory reflex to external resistance to breathing. MATERIALS AND METHODS: Inspiratory resistive loads were used 11, 28, 54, and 78 cmAq/l/s to model a conditioned respiratory reflex. External respiration was parametrized on the basis of the analysis of motor and ventilatory outputs. Conditioned signals were pure sounds exceeding the threshold of perception by 10 db at 2000 Hz frequency. All the test persons were divided into two groups (large and small groups) according to the initial reinforcement value. (1) In the large group (37 individuals), the conditioned reflex was formed from 11 cmAq/l/s that was subsequently increased stepwise in the load to 76 cmAq/l/s. (2) In the small group (18 individuals), the initial reinforcements were different gradations of resistive loads, with a stepwise transition to the other parameters of an unconditioned stimulus. The period of the isolated application of a conditioned signal (CS) was 20 s, the interval between signals was not fixed, varying from 2 min to 4 min. Six to eight combinations of the conditioned and unconditioned stimuli were used for 1 day of the experiment. RESULTS: The increase in the added respiratory resistance was associated with the pronounced reduction of pulmonary and alveolar ventilation, that is, with the hypoventilation type of resistive load realization. Changes in ventilation during the isolated application of a conditioned signal had an alternative character. In particular, as the reinforcement factor increased, a pronounced shift to hyperventilation was noted. CONCLUSION: The reinforcement value of the conditioned reflex changed stepwise, thereby significantly restructuring the proportion between the effectiveness of the adaptive activity in the realization of external resistance to inspiration (the time of stay under a certain load) and its physiological cost (totalities of the deviations of physiological and energy parameters).

An Open-Loop Receiver Architecture for Monitoring of Ionospheric Scintillations by Means of GNSS Signals

The quality of positioning services based on Global Navigation Satellite Systems (GNSS) is improving at a fast pace, driven by the strict requirements of a plethora of new applications on accuracy, precision and reliability of the services. Nevertheless, ionospheric errors still bound the achievable performance and better mitigation techniques must be devised. In particular, the harmful effect due to non-uniform distribution of the electron density that causes amplitude and phase variation of the GNSS signal, usually named as scintillation effects. For many high-accuracy applications, this is a threat to accuracy and reliability, and the presence of scintillation effect needs to be constantly monitored. To this purpose, traditional receivers employ closed-loop tracking architectures. In this paper, we investigate an alternative architecture and a related metric based on the statistical processing of the received signal, after a code-wipe off and a noise reduction phase. The new metric is based on the analysis of the statistical features of the conditioned signal, and it brings the same information of the S 4 index, normally estimated by means of closed-loop receivers. This new metric can be obtained at a higher rate as well as in the case of strong scintillations when a closed-loop receiver would fail the tracking of the GNSS signals.