We study the electroencephalogram ͑EEG͒ of 30 closed-eye awake subjects with a technique of analysis recently proposed to detect punctual events signaling rapid transitions between different metastable states. After single-EEG-channel event detection, we study global properties of events simultaneously occurring among two or more electrodes termed coincidences. We convert the coincidences into a diffusion process with three distinct rules that can yield the same only in the case where the coincidences are driven by a renewal process. We establish that the time interval between two consecutive renewal events driving the coincidences has a waiting-time distribution with inverse power-law index Ϸ 2 corresponding to ideal 1 / f noise. We argue that this discovery, shared by all subjects of our study, supports the conviction that 1 / f noise is an optimal communication channel for complex networks as in art or language and may therefore be the channel through which the brain influences complex processes and is influenced by them.

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Marabotti C, Scalzini A, Cialoni D, Passera M, L'Abbate A, Bedini R. Cardiac changes induced by immersion and breath-hold diving in humans. J Appl Physiol 106: 293-297, 2009. First published May 8, 2008 doi:10.1152/japplphysiol.00126.2008.-To evaluate the separate cardiovascular response to body immersion and increased environmental pressure during diving, 12 healthy male subjects (mean age 35.2 Ϯ 6.5 yr) underwent two-dimensional Doppler echocardiography in five different conditions: out of water (basal); head-out immersion while breathing (condition A); fully immersed at the surface while breathing (condition B) and breath holding (condition C); and breath-hold diving at 5-m depth (condition D). Heart rate, left ventricular volumes, stroke volume, and cardiac output were obtained by underwater echocardiography. Early (E) and late (A) transmitral flow velocities, their ratio (E/A), and deceleration time of E (DTE) were also obtained from pulsed-wave Doppler, as left ventricular diastolic function indexes. The experimental protocol induced significant reductions in left ventricular volumes, left ventricular stroke volume (P Ͻ 0.05), cardiac output (P Ͻ 0.001), and heart rate (P Ͻ 0.05). A significant increase in E peak (P Ͻ 0.01) and E/A (P Ͻ 0.01) and a significant reduction of DTE (P Ͻ 0.01) were also observed. Changes occurring during diving (condition D) accounted for most of the changes observed in the experimental series. In particular, cardiac output at condition D was significantly lower compared with each of the other experimental conditions, E/A was significantly higher during condition D than in conditions A and C. Finally, DTE was significantly shorter at condition D than in basal and condition C. This study confirms a reduction of cardiac output in diving humans. Since most of the changes were observed during diving, the increased environmental pressure seems responsible for this hemodynamic rearrangement. Left ventricular diastolic function changes suggest a constrictive effect on the heart, possibly accounting for cardiac output reduction. diving response; hemodynamics PREVIOUS STUDIES ON NATURAL divers (mainly marine mammals) showed that breath-hold diving is associated with energy-saving cardiovascular changes, i.e., a marked reduction in cardiac output [due to the reduction of both stroke volume and heart rate (HR)] and the redistribution of blood flow away from skin and myoglobin-rich muscles in favor of brain and heart (7,28,30). For years, however, technical difficulties have prevented a comprehensive assessment of cardiovascular changes during breath-hold diving in humans. Most of the knowledge on human diving physiology has been obtained from the study of head-out immersed subjects (9, 27), or extrapolated from the results obtained in breath-holding subjects, either with or without face immersion (2, 8, 10). The recent wide diffusion of recreational and competitive breath-hold diving (with a progressive increase of attained depths) highlighted the presence of serious divingrelated patholo...

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Gemignani A, L=Abbate A. Early subclinical increase in pulmonary water content in athletes performing sustained heavy exercise at sea level: ultrasound lung comet-tail evidence. Am J Physiol Heart Circ Physiol 301: H2161-H2167, 2011. First published August 26, 2011; doi:10.1152/ajpheart.00388.2011.-Whether prolonged strenuous exercise performed by athletes at sea level can produce interstitial pulmonary edema is under debate. Chest sonography allows to estimate extravascular lung water, creating ultrasound lung comet-tail (ULC) artifacts. The aim of the study was to determine whether pulmonary water content increases in Ironmen (n ϭ 31) during race at sea level and its correlation with cardiopulmonary function and systemic proinflammatory and cardiac biohumoral markers. A multiple factor analysis approach was used to determine the relations between systemic modifications and ULCs by assessing correlations among variables and groups of variables showing significant pre-post changes. All athletes were asymptomatic for cough and dyspnea at rest and after the race. Immediately after the race, a score of more than five comet tail artifacts, the threshold for a significant detection, was present in 23 athletes (74%; 16.3 Ϯ 11.2; P Ͻ 0.01 ULC after the race vs. rest) but decreased 12 h after the end of the race (13 athletes; 42%; 6.3 Ϯ 8.0; P Ͻ 0.01 vs. soon after the race). Multiple factor analysis showed significant correlations between ULCs and cardiac-related variables and NH2-terminal pro-brain natriuretic peptide. Healthy athletes developed subclinical increase in pulmonary water content immediately after an Ironman race at sea level, as shown by the increased number of ULCs related to cardiac changes occurring during exercise. Hemodynamic changes are one of several potential factors contributing to the mechanisms of ULCs. pulmonary edema EVEN IN HEALTHY SUBJECTS EXTREMELY demanding endurance exercise leads to functional and structural cardiac and pulmonary changes, along with local and systemic responses, reflecting oxidative, metabolic, hormonal, and thermal stress, besides immunomodulation and inflammatory reaction (4,30,32,40,41,46). Whether interstitial pulmonary edema occurs in athletes performing heavy sea level exercise is debated (2,6,12,18,19,27,28,44,56). Interstitial pulmonary edema has been documented in endurance athletes performing heavy sea level exercise, using imaging techniques such as chest X-ray, magnetic resonance, computed tomography, and scintigraphy (17,36,56). Previous authors measured noninvasively the postexercise extracellular thoracic fluid volume using thoracic impedance monitoring (16). However, this method does not allow visualizing the seat of the water content in the chest. Chest sonography can be used in the field for assessment of athletes immediately after the end of exercise (11,34,35). This technique effectively detects and quantifies extravascular lung water, creating ultrasound lung comet-tail (ULC) artifacts from water-thickened pulmonary interlobular septa (11). In a pi...

We propose a model for the passage between metastable states of mind dynamics. As changing points we use the rapid transition processes simultaneously detectable in EEG signals related to different cortical areas. Our model consists of a non-Poissonian intermittent process, which signals that the brain is in a condition of complexity, upon which a Poisson process is superimposed. We provide an analytical solution for the waiting-time distribution for the model, which is well obeyed by physiological data. Although the role of the Poisson process remains unexplained, the model is able to reproduce many behaviors reported in literature, although they seem contradictory.

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