Vol.:(0123456789) 1 3 Experimental Brain Research https://doi.org/10.1007/s00221-019-05490-6 RESEARCH ARTICLE The infuence of microgravity on cerebral blood fow and electrocortical activity Timo Klein 1,2  · Petra Wollseifen 1  · Marit Sanders 3  · Jurgen Claassen 3  · Heather Carnahan 4  · Vera Abeln 1  · Tobias Vogt 5  · Heiko K. Strüder 1  · Stefan Schneider 1,2,4 Received: 2 December 2018 / Accepted: 4 February 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Changes in gravity conditions have previously been reported to infuence brain hemodynamics as well as neuronal activity. This paper attempts to identify a possible link between changes in brain blood fow and neuronal activity during microgravity. Middle cerebral artery fow velocity (MCAv) was measured using Doppler ultrasound. Brain cortical activity (i.e., cortical current density) was measured using electroencephalography. Finger blood pressure was recorded and exported to gener- ate beat-by-beat systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), and cerebrovascular conductance index (CVCi). Seventeen participants were evaluated under normal gravity conditions and microgravity conditions, during 15 bouts of 22-s intervals of weightlessness during a parabolic fight. Although MAP decreased and CO increased, MCAv remained unchanged in the microgravity condition. CVCi as the quotient of MCAv and MAP increased in microgravity. Cortical current density showed a global decrease. Our data support earlier data reporting a decrease in the amplitude of event-related potentials recorded during microgravity. However, the general decrease in neural excitability in microgravity seems not to be dependent on hemodynamic changes. Keywords Parabolic fight · EEG · Transcranial Doppler ultrasound · MCA Introduction In the last decades there has been a number of studies report- ing on cognitive impairment during space fight (Fowler and Manzey 2000; Bock et al. 2001; Heuer et al. 2003), (Money and Cheung 1991; Bock et al. 1992, 2003; Lackner and DiZio 1992; Hermsdörfer et al. 1999, 2000; Jüngling et al. 2002; Augurelle et al. 2003). Unfortunately those studies barely diferentiated between a primary efect of weightless- ness and a secondary efect of the stressful environment. Indeed, deteriorations in cognitive performance were often monitored in transition phases (e.g., start or end) of mis- sions, suggesting a possible impact of stress. In the latter years, experimental protocols on board of the International Space Station (ISS) were adjusted in order to further inves- tigate gravity-related modulation of neural processing, e.g., visual perception: (Cheron et al. 2014). Simultaneously, a number of neuroscientifc experiments has been conducted on board of parabolic fight (Saradjian et al. 2014) allowing to discriminate between primary efects of weightlessness and secondary efects of stress and/or isolation. Although parabolic fights are well known to induce stress (Schneider Timo Klein and Petra Wollseifen share the frst authorship. * Stefan Schneider schneider@dshs-koeln.de 1 Institute of Movement and Neurosciences, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany 2 Faculty of Science Health and Education, University of the Sunshine Coast, Maroochydore, Australia 3 Department of Geriatric Medicine, Radboud Alzheimer Centre, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 925 PO box 9101, 6500 HB Nijmegen, The Netherlands 4 School of Maritime Studies, Ofshore Safety and Survival Centre, Marine Institute, Memorial University of Newfoundland, St. John’s, Canada 5 Institute of Professional Sport Education and Sport Qualifcations, German Sport University Cologne, Cologne, Germany