Electrical activity of the brain during isocapnic hyperventilation with cold air

The influence of hyperventilation on the electrical activity of the brain has conventionally been the subject of study of physiologists. The role of the brain in the adaptation to the inhalation of cold air remains to be understood in more detail. The aim of the study was to determine certain features of the cerebral response to isocapnic hyperventilation with cold air and to reveal the correlation of its electric activity in different modes of ventilation, with the pattern of quiet breathing and the forced expiration parameters. Twenty-one apparently healthy volunteers were subjected to comprehensive functional examination. Qualitative differences in the ?-rhythm relative power were revealed under the conditions of isocapnic hyperventilation with cold air. The specific features of the correlation of the electrical activity of the brain provoked by cold with the breathing pattern and the bronchomotor tone were revealed.     

Bronchial reactivity in asthmatic adults with normal spirometric values.

A comparison was made between airways obstruction produced by exercise. Hyperventilation of cold air, hyperventilation of room air, and inhalation of ultrasonically nebulised distilled water. Seven asthmatics with no airflow obstruction were studied together with seven normal controls. All four provocations produced comparable mean reductions in forced expired volume in one second in the asthmatic patients, but no reduction was obtained in the controls. Whereas exercise, hyperventilation of cold air, and hyperventilation of room air were associated with heat loss from airways, inhalation of nebulised distilled water was not. Inhalation of ultrasonically nebulised distilled water offers a simple additional diagnostic test for asthma. Changes in the osmolality of airway surface liquid may possibly be the common mechanism by which "fog" and hyperventilation produce bronchoconstruction.     

Interrelations between EEG Parameters and Personality Characteristics in Parkinsonian Patients

We studied a number of EEG parameters and indices of personality characteristics (evaluated with the use of the MMPI questionnaire) in sixty 44- to 73-year-old patients with Parkinson's disease (PD). According to the intensity of the symptoms, they were classified into groups 1 and 2, with an initial or moderate level of disease manifestation. In group-2 patients, the powers of the - and -range rhythms were greater, as compared with those in group 1. This was combined with higher indices in scales 2 (depression, D), 8 (individualism, Sc), and 0 (introversion/extraversion, Si). A clear correlations between the EEG parameters and indices of personality structure were found. There were positive correlations between the normalized power of ₂-rhythm and values of a few MMPI scales: 1 (supercontrol, Hs), 2 (depression, D), 4 (impulsivity, Pd), 7 (anxiety, Pt), 8 (individualism, Sc), and 0 (introversion/extraversion, Si). We also found negative correlations between the frequency of -rhythm and indices of supercontrol and anxiety scales. Correlations between different EEG parameters and MMPI scale indices depended on the level of disease manifestation. Our results allow us to assume a certain generality of the neurophysiological mechanisms determining modifications of the integral electrical activity of the brain and formation of individual psychological characteristics in parkinsonian patients.     

Intensity and type of EEG reactions to a hyperventilation test and their relationship with changes in patients’ subjective state of health and some characteristics of the initial EEG pattern

Some EEG characteristics at rest and after a 3-min hyperventilation test (HVT) were studied in 100 adult patients along with the changes in their current subjective state of health, assessed with the help of a special three-stage survey and a questionnaire. Our findings demonstrated a clear correlation between the rate of changes in the current subjective state of health of a patient, the average number of observed symptoms, and the intensity of the EEG reaction. With regard to the methodological aspect, we recorded a difference in the assessment of subjective data obtained through the different types of survey. The frequency of two types of high-amplitude slow waves during the HVT (recorded in 21% of patients), as well as of paroxysmal epileptiform activity, was studied, and their correlation with the clinical manifestations of epilepsy was analyzed. Our study showed that the intensity of the general EEG reaction to the HVT is correlated with the presence of EEG disorders, such as minor bursts in the initial EEG pattern; the probability of high-amplitude slow activity during the HVT is especially high if these minor bursts are recorded at rest. We also noted a certain relationship between the intensity of hyperventilation-related EEG changes (and, therefore, the rate of changes in the current subjective state of health of a patient) and characteristics of the initial pattern, such as α-rhythm disorders and an increase in the intensity of slow or slow and frequent activity at rest.     

Effect of cold and warm dry air hyperventilation on canine airway blood flow

Tracheobronchial blood flow increases with cold air hyperventilation in the dog. The present study was designed to determine whether the cooling or the drying of the airway mucosa was the principal stimulus for this response. Six anesthetized dogs (group 1) were subjected to four periods of eucapnic hyperventilation for 30 min with warm humid air [100% relative humidity (rh)], cold dry air (-12 degrees C, 0% rh), warm humid air, and warm dry air (43 degrees C, 0% rh). Five minutes before the end of each period of hyperventilation, tracheal and central airway blood flow was determined using four differently labeled 15-micron diam radioactive microspheres. We studied another three dogs (group 2) in which 15- and 50-micron microspheres were injected simultaneously to determine whether there were any arteriovenous communications in the bronchovasculature greater than 15 micron diam. After the last measurements had been made, all dogs were killed, and the lungs, including the trachea, were excised and blood flow to the trachea, left lung bronchi, and parenchyma was calculated. Warm dry air hyperventilation produced a consistently greater increase in tracheobronchial blood flow (P less than 0.01) than cold dry air hyperventilation, despite the fact that there was a smaller fall (6 degrees C) in tracheal tissue temperature during warm dry air hyperventilation than during cold dry air hyperventilation (11 degrees C), suggesting that drying may be a more important stimulus than cold for increasing airway blood flow. In group 2, the 15-micron microspheres accurately reflected the distribution of airway blood flow but did not always give reliable measurements of parenchymal blood flow.     

Individual typological features in the EEG of athletes after acute hypoxic treatment

In athletes with different types of physical training and various temperaments, variability of the main rhythms of the EEG (??, ??, and ??) and the parameters of the desynchronization response of the ??-rhythm, the individual extent of the decrease in the power of the ??-rhythm during eye opening under the conditions of hypoxia growing from 20.9 to 10% of O₂ were studied. Twenty-four 18- to 26-year-old athletes, including 11 swimmers and 13 skiers, were involved in the study. We found that, in contrast to normoxia conditions, hypoxia was associated with the instability of the spectrum of the EEG rhythms and phasic changes during a 25-min hypoxia. The EEG response during hypoxia depended on individual typological features estimated using Strelau??s temperament questionnaire. Negative correlation between the psychological construct ??endurance?? measured using the FCB-TI questionnaire (Formal Characteristics of Behavior-Temperament Inventory) and the power of the EEG ??-rhythm was found. The parameters of training and the features of the respiration pattern that appeared as a consequence of training modulated the sensitivity of brain structures to hypoxia, which was reflected in the changes in the EEG ??-rhythm under hypoxia conditions.     

EEG power spectra in simulation of disruptiveness

For analysis of the action of destructive behavior, the EEG power spectra in groups with different levels of disruptiveness at rest and during the modeling of destructive behavior were studied. The destructive processes in the group of less destructive subjects of the experiment are accompanied by the development of activation processes of specific and nonspecific character (??₁-rhythm power loss and ??₂-rhythm power growth). This allows critical assessment of the incoming stimuli, generation of adequate behavioral responses, and inhibition of aggression. In the group of the subjects of the experiment with a high level of destructiveness activation, the criteria are less distinct. The criteria of excessive activation from diencephalic structures are observed (?? rhythm power growth), which may be connected with the development of earlier and less stable mechanisms of behavior regulation and help to select more primitive behavioral models, including aggression.     

Cold-induced bronchoconstriction: role of cutaneous reflexes vs. direct airway effects

To determine the relative contributions of direct airway vs. reflex cutaneous thermal receptor stimulation in cold-induced bronchoconstriction, we isolated these two aspects of cold exposure in 10 asthmatics and 13 normal subjects. Ice packs were applied to the skin of the face, chest, thigh, and upper arm in random sequence while serially measuring specific conductance. In this fashion a limited mapping of skin-mediated bronchoconstriction was established. Warm packs were applied to the same areas of control for any potential nonspecific stimulatory effects. Cooling the skin induced bronchoconstriction to a similar degree in both groups; this effect was very small, did not induce symptoms, and was only seen with stimulation of the face. At another time, the subjects performed isocapnic hyperventilation of frigid air to ascertain their response to direct airway cooling. A moderate but significant correlation existed between skin and airway sensitivity; however, the magnitude of the two responses differed markedly. Breathing cold air at rest had no effect on lung function; however, elevating ventilation promptly produced bronchial narrowing. Hence, in a cold environment, the most potent stimulus for the development of airway obstruction in asthmatics derives from a direct airway effect.     

Success of the test task performance by students with different spectral α-rhythm characteristics in the baseline electroencephalogram

The subjects were divided into two groups according to the α₁ and α₂ spectral powers in the occipital derivations of the EEG recorded in the initial state with their eyes closed. Group I included subjects whose α₁-rhythm spectral power (7–10 Hz) was more than 70% of the total α-rhythm band power. Group II included subjects whose α₂-rhythm spectral power (10–13 Hz) was more than 70% of the total α-rhythm band power. It was established that, in the tasks requiring prediction of the subsequent result (memorizing a certain sequence of signals and its subsequent reproduction on the monitor screen), group I subjects differed from group II subjects in fewer sequence errors and a greater number of accurate predictions. In group II subjects, a decrease in the ϑ-band spectral power in the EEG of the central and frontal cortical areas was observed compared to the baseline. Therefore, the EEG ϑ-rhythm power at the memorizing stage was lower in them than in group II subjects. The results suggest that the baseline characteristics of ϑ-activity can be regarded as prognostic criteria of similar types of activity.     

Parameters of cortical interactions in subjects with high and low levels of verbal creativity

Parameters of cortical interactions depending on the level of creative achievements were studied in 40 right-handed subjects (22 men and 18 women). EEG was recorded at rest and during performance of a verbal creativity task (the Cognitive Synthesis test). The subjects were divided (by the median split) into groups with high and low originality scores (OSs). EEG coherence was computed within a range of frequencies from 4 to 30 Hz. The total values of coherence were determined separately for intra- and interhemispheric coherent connections using each of 16 electrode sites. Unlike subjects with a low OS, those with a high OS values were characterized by a decrease in the interhemispheric coherence of the θ_1,2-rhythm bioelectric potentials, which was especially pronounced in frontal cortical regions, and by an increased β₁-rhythm interhemispheric coherence in the occipital and temporal-parietal brain regions. The results are discussed in the context of right- and left-hemisphere contributions into the top-down and bottom-up regulation mechanisms during creative thinking.     

Interrelations of hypocapnia, hypoxia, cerebral blood flow and electrical activity of the brain under voluntary hyperventilation in humans

Changes of different physiological parameters in human caused by hyperventilation of 3-min and longer duration were investigated and correlated. It was found that during 3-min hyperventilation, resulting in 4.5-5 fold increase of the respiration velocity, similar phasing changes of the central and cerebral haemodynamics occurred. The blood flow velocity according to the rheographic data during the hyperventilation first increases, reaching maximum at 1st - 2nd min of the test, and then decreases, reaching minimum at 2nd - 3rd min after it's end, and then slowly increases. Cerebral blood flow velocity during all the 3 min of the hyperventilation in most of the subjects keeps being increased, and after the test - decreased. At the same time transcutaneous pressure of carbon dioxide changes differently - decreases to minimum (approximately 25 mmHg) at the end of the test and then increases, reaching approximately 90% of the background level, at 5th min after the end of the test. Oxygen saturation of the blood during the test is found to be 98-100% and decreases to 90% at 5th min after it's end, which in overall with cerebral blood flow decrease appears to be the factor of the brain's hypoxia. In different subjects "mirror" changes of the EEG spectral power of different EEG ranges in relation to transcutaneous pressure of carbon dioxide dynamics were revealed by the hyperventilation. Taking into account the factors of duration or recurrence of the hyperventilation is important for the understanding the interrelations of cerebral haemodynamics, hypocapnia, hypoxia and electrical activity of the brain. It was found that after the recurrent hyperventilation of increasing amount (several times in hour by 3 min) cerebral blood flow might decrease markedly against the background of relatively small changes of electrical activity of the brain. The discussing of the data presented in the paper is carried out from the point of view of important role of tissue oxygen utilization mechanisms of the brain in adaptation to hypoxia and hypocapnia.     

Changes in the EEG power in male and female subjects during visual creative thinking

Gender-related differences in EEG patterns during creative visual thinking were investigated in 10 men and 10 women. The spectral power density was analyzed in the range of 4-30 Hz. Gender differences in the hemispheric asymmetry of theta1-rhythm desynchronization were found: females demonstrated greater desynchronization in the right hemisphere than in the left hemisphere, whereas no asymmetry was revealed in males. Only in women numerous negative correlations between creativity indices and task-induced theta1 desynchronization were found.     

Interhemispheric differences in the spectral power and coherence of EEG rhythms in children with autism spectrum disorders

Electroencephalographic examination of boys aged 4–9 years with autism spectrum disorders (ASDs) showed spectral power values and coherence in high-frequency bands (20–60 Hz) in various brain areas were higher than normal. Differences in spectral power were greater in the anterior areas of the left hemisphere; differences in coherence, in the right anterior and posterior areas. Interhemispheric differences typical of healthy subjects were absent in the children with ASDs. The spectral power of the θ rhythm was lower in autism, especially in the left hemisphere. The spectral power of the α rhythm in the autistic children was lower than normal, especially in the posterior areas of the left hemisphere. The μ rhythm was higher than normal in spectral power and was localized in the right, rather than left, anterior areas. The children were examined again after corrective procedures. The α-rhythm spectral power increased (became closer to the norm) in the left posterior areas, while the γ-rhythm spectral power decreased (became closer to the norm) in the right anterior areas in some of the autistic children. The electrophysiological changes were associated with improved psychological testing results, especially in nonverbal measures.     

Effect of autonomic blockade on tracheobronchial blood flow

Tracheobronchial blood flow increases two to five times in response to cold and warm dry air hyperventilation in anesthetized tracheostomized dogs. In this series of experiments we have attempted to attenuate this increase by blockade of the autonomic nervous system. Four groups of anesthetized, tracheostomized, open-chest dogs were studied. Group 1 (n = 5) were hyperventilated for 30 min with 1) warm humid [approximately 26 degrees C, 100% relative humidity, (rh)] air followed by bilateral vagotomy, 2) warm humid air, 3) cold (-22 degrees C, 0% rh) dry air, and 4) warm humid air. Groups 2, 3, and 4 (n = 3/group) were hyperventilated for 30 min with 1) warm humid (approximately 41 degrees C, 100% rh) air, 2) warm dry (approximately 41 degrees C) air, 3) warm humid air, and 4) warm dry air. Group 2 were controls. Group 3 were given phentolamine, 0.6 mg/kg intravenously, as an alpha-blockade, and group 4 were given propranolol, 1 mg/kg, as a beta-blockade after warm dry air hyperventilation (period 2). Five minutes before the end of each 30-min period of hyperventilation, measurements of vascular pressures, cardiac output, arterial blood gases, and inspired, body, and tracheal temperatures were measured, and differently labeled radioactive microspheres were injected into the left atrium to make separate measurements of airway blood flow. After the last measurements had been made animals were killed and their lungs were excised. Blood flow to the airways and lung parenchyma was calculated.(ABSTRACT TRUNCATED AT 250 WORDS)     

The pathological dominant and the stable pathological state]

The pathological dominant is considered at a model of alcohol motivation which is in competitive relations with drinking motivation. The steady pathological state is considered at a model of seizure readiness in rats with audiogenic epileptiform seizures. The alcohol motivation might be ceased by the activation of competitive systems (thirst motivation), but the level of seizure readiness might be lowered intrasystemically, for example, by the habituation mechanisms.     

The Functional State of Athletes Addicted to Exercises during Exercise Deprivation

The objective of this study is to identify markers of the addictive condition developing in athletes during exercise deprivation by analyzing electroencephalograms (EEGs), electromyograms (EMGs), skin temperature measurements, sympathetic nervous system activity, levels of anxiety and depression (by psychological tests). A cohort of professional football players (N = 50) voluntarily participated in the study. The athletes were tested under two test conditions: during active training sessions and during exercise deprivation (for seven days). The analyzed results have shown that the functional state of athletes with exercise addiction (due to exercise deprivation), compared with athletes showing no addictive behavior, was characterized by lower brain bioelectric activity (a decrease in the α-rhythm amplitude and power), growth in the muscular tension, increased sympathetic activity, and elevated levels of anxiety and depression. We have concluded that an athlete’s functional state during exercise deprivation is an important predictor for exercise dependence. A prolonged exercise deprivation causes intense psychophysiological changes in the body of athletes inclined to exercise addiction. The obtained results may be useful for experts in the field of sports medicine, as well as for further studies in different types of addictions.     

Role of tracheal and bronchial circulation in respiratory heat exchange

Due to their anatomic configuration, the vessels supplying the central airways may be ideally suited for regulation of respiratory heat loss. We have measured blood flow to the trachea, bronchi, and lung parenchyma in 10 anesthetized supine open-chest dogs. They were hyperventilated (frequency, 40; tidal volume 30-35 ml/kg) for 30 min or 1) warm humidified air, 2) cold (-20 degrees C dry air, and 3) warm humidified air. End-tidal CO2 was kept constant by adding CO2 to the inspired ventilator line. Five minutes before the end of each period of hyperventilation, measurements of vascular pressures (pulmonary arterial, left atrial, and systemic), cardiac output (CO), arterial blood gases, and inspired, expired, and tracheal gas temperatures were made. Then, using a modification of the reference flow technique, 113Sn-, 153Gd-, and 103Ru-labeled microspheres were injected into the left atrium to make separate measurements of airway blood flow at each intervention. After the last measurements had been made, the dogs were killed and the lungs, including the trachea, were excised. Blood flow to the trachea, bronchi, and lung parenchyma was calculated. Results showed that there was no change in parenchymal blood flow, but there was an increase in tracheal and bronchial blood flow in all dogs (P less than 0.01) from 4.48 +/- 0.69 ml/min (0.22 +/- 0.01% CO) during warm air hyperventilation to 7.06 +/- 0.97 ml/min (0.37 +/- 0.05% CO) during cold air hyperventilation.     

Hypertonic aerosol inhalation does not alter central airway blood flow in dogs

Tracheobronchial blood flow in dogs increases with cold or dry air hyperventilation, possibly as a result of airway drying leading to increased osmolarity of airway surface fluid. This study was designed to examine whether administration of aerosols of various tonicity to alter airway surface fluid osmolarity would induce similar blood flow changes. Tracheobronchial blood flow was measured by the radioactive microsphere technique in six anesthetized dogs ventilated with warm humid air (100% relative humidity) for 15 min (period 1), air containing ultrasonically nebulized saline aerosol (1,711 mosmol/kg) for 3 min (period 2) and 12 min (period 3), and the same aerosol at a higher nebulizer output for a further 3 min (period 4). Between periods 3 and 4, the dogs were ventilated with warm humid air for 30 min to reestablish base-line conditions. In another five dogs, measurements were made after 30 min of ventilation with 1) warm humid air, 2) isotonic saline aerosol, 3) warm humid air, 4) distilled water aerosol (3 dogs), and hypertonic saline aerosol (2 dogs). After the last measurement was made, each dog was killed, the trachea and major bronchi were excised, and blood flow was calculated. No change in blood flow was found during any period of aerosol inhalation. The osmolar load imposed on the airways was estimated and was similar to that occurring during cold or dry air hyperventilation. These data suggest that increasing osmolarity of airway surface fluid does not explain the blood flow changes seen during hyperventilation of cold or dry air.     

Detection of changes in the mouse circadian rhythm induced by stress

Mice were subjected to three types of acute stress (cold, forced swimming and tail hanging) in order to investigate the effects of stress on the motor activity circadian rhythm. This rhythm was studied using the cosinor method and spectral analysis. A statistically significant decrease in the amplitude and the power content of the circadian harmonic was found after stress application. These decreases could be due to a desynchronization of the circadian oscillators which drive the rhythm. The use of the power content of the circadian harmonic is proposed for the detection of the alterations due to stress.     

Consistency of the counting talk test for exercise prescription

The purpose of this study was to assess the consistency of the counting talk test (CTT) method for estimating exercise intensity across various modes of exercise in healthy young adults. Thirty-six individuals completed the study, which required participation in 3 separate sessions within a 2-week time period. During the first session, the individuals completed a maximal effort treadmill test from which each individual's heart rate reserve (HRR) was calculated. During the second and third sessions, the subjects participated in 2 modes of exercise in each session for a total of 4 different modes of exercise. The individuals exercised at 40% HRR, 50% HRR, 60% HRR, 75% HRR, and 85% HRR. The heart rate (HR), CTT, and rating of perceived exertion (RPE) were recorded at each workload. Based on the individual's resting CTT (CTT(rest)), the %CTT for each exercise stage was then calculated. Pearson correlations demonstrated moderate to good correlations between the CTT and HRR methods and the CTT and RPE methods for estimating exercise intensity. This study found that for the individuals with CTT(rest) <25, moderate to vigorous intensity exercise as recommended by the American College of Sports Medicine HRR guidelines could be achieved by exercising at a level of 40-50% CTT(rest). Individuals with a CTT(rest) ≥25, exercising at a level of 30-40% CTT(rest) would place them in the moderate to vigorous exercise intensity range. A high degree of reliability was demonstrated using the CTT method across the various modes of aerobic exercise. As such, independent of the exercise mode, the CTT was found to be an easy and consistent method for prescribing moderate to vigorous aerobic exercise intensity.