title: Prolonged dry apnoea: effects on brain activity and physiological functions in breath-hold divers and non-divers.
abstract: OBJECTIVE
  The aim of the study was to investigate the effects of voluntary breath-holding on brain activity and physiological functions. We hypothesised that prolonged apnoea would trigger cerebral hypoxia, resulting in a decrease of brain performance; and the apnoea's effects would be more pronounced in breath-hold divers.
  
  
  METHODS
  Trained breath-hold divers and non-divers performed maximal dry breath-holdings. Lung volume, alveolar partial pressures of O2 and CO2, attention and anxiety levels were estimated. Heart rate, blood pressure, arterial blood oxygenation, brain tissue oxygenation, EEG, and DC potential were monitored continuously during breath-holding.
  
  
  RESULTS
  There were a few significant changes in electrical brain activity caused by prolonged apnoea. Brain tissue oxygenation index and DC potential were relatively stable up to the end of the apnoea in breath-hold divers and non-divers. We also did not observe any decrease of attention level or speed of processing immediately after breath-holding. Interestingly, trained breath-hold divers had some peculiarities in EEG activity at resting state (before any breath-holding): non-spindled, sharpened alpha rhythm; slowed-down alpha with the frequency nearer to the theta band; and untypical spatial pattern of alpha activity.
  
  
  CONCLUSIONS
  Our findings contradicted the primary hypothesis. Apnoea up to 5 min does not lead to notable cerebral hypoxia or a decrease of brain performance in either breath-hold divers or non-divers. It seems to be the result of the compensatory mechanisms similar to the diving response aimed at centralising blood circulation and reducing peripheral O2 uptake. Adaptive changes during apnoea are much more prominent in trained breath-hold divers.
authors.affiliation: Department of Higher Nervous Activity, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234, Leninskie Gory 1/12, Moscow, Russia. patricia@neurobiology.ru.
authors.forename: Patricia
authors.initials: P
authors.lastname: Ratmanova
authors.affiliation: Department of Higher Nervous Activity, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234, Leninskie Gory 1/12, Moscow, Russia.
authors.forename: Roxana
authors.initials: R
authors.lastname: Semenyuk
authors.affiliation: Institute of Biomedical Problems of the Russian Academy of Sciences, 123007, Khoroshevskoye Sh., 76A, Moscow, Russia.
authors.forename: Daniil
authors.initials: D
authors.lastname: Popov
authors.affiliation: Institute of Biomedical Problems of the Russian Academy of Sciences, 123007, Khoroshevskoye Sh., 76A, Moscow, Russia.
authors.forename: Sergey
authors.initials: S
authors.lastname: Kuznetsov
authors.affiliation: Institute of Biomedical Problems of the Russian Academy of Sciences, 123007, Khoroshevskoye Sh., 76A, Moscow, Russia.|Russian Olympic Committee Innovation Center, 119991, Luzhnetskaya Embankment 8, Moscow, Russia.
authors.forename: Irina
authors.initials: I
authors.lastname: Zelenkova
authors.affiliation: Department of Higher Nervous Activity, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234, Leninskie Gory 1/12, Moscow, Russia.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Napalkov
authors.affiliation: Institute of Biomedical Problems of the Russian Academy of Sciences, 123007, Khoroshevskoye Sh., 76A, Moscow, Russia.
authors.forename: Olga
authors.initials: O
authors.lastname: Vinogradova
mesh_terms: D000328:Adult; D001049:Apnea / Q000150:complications / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D062485:Breath Holding; D004242:Diving; D005260:Female; D006801:Humans; D002534:Hypoxia, Brain / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption; D013997:Time Factors
chemical_list: D010100:Oxygen
keywords: Attention level; Brain tissue oxygenation; Breath-holding; DC potential; Dry static apnoea; EEG